UNITED STATES TARIFF COMMISSION

SYNTHETIC RESINS
AND THEIR RAW MATERIALS

REPORT No. 131
SECOND SERIES

For sale by the Superintendent of Documents, Government Printing Office, Washington, D. C., at the prices indicated

[i]

UNITED STATES TARIFF COMMISSION

SYNTHETIC RESINS
AND THEIR RAW MATERIALS

A SURVEY OF THE TYPES AND USES OF SYNTHETIC
RESINS, THE ORGANIZATION OF THE INDUSTRY,
AND THE TRADE IN RESINS AND RAW
MATERIALS, WITH PARTICULAR
REFERENCE TO FACTORS
ESSENTIAL TO TARIFF
CONSIDERATION

UNDER THE GENERAL PROVISIONS OF SECTION 332, TITLE III,
PART II, TARIFF ACT OF 1930

REPORT No. 131
SECOND SERIES

UNITED STATES
GOVERNMENT PRINTING OFFICE
WASHINGTON: 1938

For sale by the Superintendent of Documents, Washington, D. C. Price 25 cents

In the preparation of this report, the Commission had the services of Paul K. Lawrence, Prentice N. Dean, and others of the Commission’s staff.

This survey deals with the several commercially important types of synthetic resins covered by paragraphs 2, 11, and 28 of the Tariff Act of 1930 and with the raw materials necessary for their production. It is made under the general investigatory powers of the Tariff Commission as provided in section 332 of that act.

The field of synthetic resins is a comparatively new one, most of its commercial development having occurred within the past 10 years. In 1937 the domestic output was more than 160 million pounds as compared with slightly more than 10 million pounds in 1927.

The first important patents on synthetic resins were granted about 25 years ago. These patents covered phenolic resins probably intended for use as substitutes for certain natural resins. It was soon found that these synthetics offered possibilities of application vastly greater than the natural materials. At first progress in their application was slow as is usually the case with new products. During the World War the shortage of phenol promoted interest in the use of the other tar acids as raw materials for synthetic resins and intensive research developed resins from the cresols and higher boiling tar acids. These resins possessed properties sufficiently different from those made from phenol to establish them permanently.

In the meantime research on other types of resins was carried on in the United States and in Europe. The tar-acid resins for molding were the only commercially important ones on the market until about 1929. About that time, however, new commercial products began to appear rapidly. Cast phenolic resins became available as material for novelties of unusual brilliancy and beauty, the urea resins to meet the requirements for light colored thermosetting resins in molded articles, and the alkyd resins for use in new surface coatings which replaced conventional paint materials.

Later there followed a number of thermoplastic materials offering new and unusual properties. Vinyl resins found application in molded products and in safety glass. The acrylate resins became the nearest approach to organic glass yet developed. The polystyrene resins, long in the research stage, made their commercial appearance in 1937. Resins from petroleum, from furfural, from adipic acid, and from aniline are on the market. Many others are under investigation and some of them will undoubtedly become important.

The versatility of synthetic resins is most unusual. In various uses they have successfully displaced glass, wood, metal, hard rubber, bone, glue, cellulose plastics, protein plastics, and conventional paint materials. They compete with glass in shades and reflectors and offer properties which will increase their use for this purpose. Cases for scales, radios, and clocks, formerly of wood and metal, are now made of these synthetic resins.

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Scope and purpose.

This survey deals with the synthetic resins, the nature and trade in the raw materials necessary for their production, the processes by which they are made, trade in them in the United States and between nations, and the nature of the competition which they meet. It does not go into the details of manufacture of and trade in the multitude of articles made of synthetic resins but stops at the point where these materials are turned over to the resin fabricator. The synthetic resins are but one of four broad groups of organic plastics. The others—natural resins, cellulose ethers and esters, and protein plastics—are discussed herein only as they relate to or compete with the synthetic resins.

The purpose of the survey is to bring together in one publication the available information on synthetic resins so as to provide a basis for consideration of future tariff problems. Because the industries involved are comparatively young and are expanding rapidly, their present day importance is not generally realized. The rapidity with which the synthetic resin industry is developing causes any comprehensive report on the subject to be practically out of date before it can be published. Notwithstanding the progress made each year in the quantity of production, new applications, and new commercial products, the industry may be said to be still in the industrial nursery. This circumstance necessarily limits the period during which any treatment of the subject will be representative.

Fundamental definitions.

The scope of this report has been stated to include synthetic resins up to the point where they are further manufactured, and the raw materials used in producing them. It was also stated that natural resins and synthetic plastics other than resins, such as the cellulose compounds and modified rubber compounds, are excluded. The boundaries of these categories are therefore important.[1]

The term “resin” was formerly applied exclusively to a group of natural products, principally of vegetable origin, although at least one important resin, shellac, is of animal origin.[2] These natural resins are widely used in paints, varnishes, and lacquers for decorative and protective surface coatings. They also have extensive use in textile impregnation, adhesives, soap, paper, and in cold-molded articles. In recent years the natural resins have had to compete with synthetic products, and each gravitates toward uses which demand the quality or combination of qualities which it can most completely supply.

A resin may be defined as a semisolid or solid, complex, amorphous mixture of organic compounds with no definite melting point and no tendency to crystallize. The resins are characterized by a typical luster and a conchoidal fracture rather than by definite chemical composition. The term includes natural resins, such as colophony (ordinary rosin), copal, damar, lac, mastic, sandarac, shellac, etc., sometimes called gums or gum resins although none of them are true gums.

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A synthetic resin is a resin made by synthesis from nonresinous organic compounds. The term includes materials ranging from viscous liquids to hard, infusible, amorphous solids. As a rule synthetic resins possess properties distinct from those of natural resins. The term “plastics,” sometimes applied to synthetic resins, also includes many materials which are not resins.

A plastic is anything possessing plasticity; that is, anything which can be deformed under mechanical stress without losing its coherence or its ability to keep its new form. According to this definition the term includes such materials as putty, cement, clay, glass, and metals, as well as certain modified natural or semisynthetic products, such as cellulose acetate, cellulose nitrate, and casein more commonly so designated. To speak of the plastics industries is almost meaningless because of their enormous scope, including as they do those producing cement, ceramics, confectionery and rubber, as well as those producing the semisynthetic products mentioned.

The resin industry embraces two main types of materials, thermoplastic and thermosetting. Thermoplastic materials are those which, although rigid at normal temperatures, may be deformed and molded under heat and pressure. Among such materials are the cellulose esters, acrylate resins, vinyl resins, polystyrene resins, etc. The recent development of injection molding has given thermoplastics a new significance.

Thermosetting substances are thermoplastic at some stage of their existence, but become hard, rigid, and permanently infusible upon the application of the proper heat and pressure. They are then irreversible whereas the thermoplastics are reversible. Outstanding among the thermosetting resins are tar-acid resins, urea resins, and the alkyd resins.

Tariff history.

The earliest mention of synthetic resins in the tariff laws of the United States was the provision in group III of the Emergency Tariff Act of 1916 for a duty of 30 percent ad valorem and 5 cents per pound on synthetic phenolic resins. None of the non-coal-tar synthetic resins were specifically mentioned prior to the Tariff Act of 1930.

The Tariff Act of 1922 (par. 28) provided for synthetic phenolic resin and all resinlike products, solid, semisolid or liquid, prepared from phenol, cresol, phthalic anhydride, coumarone, indene, or from any other article or material provided for in paragraph 27 or 1549. The rate of duty was 60 percent ad valorem based on American selling price or United States value and 7 cents per pound, with a provision that the ad valorem rate should be reduced to 45 percent 2 years after the passage of the act.

The Tariff Commission made two investigations of synthetic resins under section 316 of the act of 1922. The first was undertaken April 16, 1926, upon complaints of several domestic manufacturers, of unfair methods of competition and unfair acts in the importation and sale of synthetic phenolic resin, Form C, and articles made wholly or in part therefrom, in infringement of the patent rights of the Bakelite Corporation. Following the investigation, the Commission recommended on May 25, 1927, that this material (as described under United States Patents No. 942,809 and 1,424,738)[4] be excluded from entry into the United States. Importers appealed from the findings of the Commission to the Court of Customs Appeals, and the judicial proceedings were ended on October 13, 1930, by denial of a writ of certiorari for the Supreme Court of the United States to review the judgment of the Court of Customs and Patent Appeals. The latter court had held, among other things, that there was substantial evidence in support of each finding of the Commission. On November 26, 1930, the Treasury Department issued an order prohibiting the importation of synthetic phenolic resin, Form C, with certain exceptions. (T. D. 44411.)

The second investigation by the Tariff Commission was instituted on December 23, 1927, also under section 316 of the act of 1922. It concerned unfair methods of competition and unfair acts in the importation into the United States of laminated products of paper or other materials and insoluble, infusible condensation products of phenols and formaldehyde. The Commission recommended to the President that, until March 4, 1929, inclusive, certain products covered by United States Letters Patent Nos. 1,018,385, 1,019,406, and 1,037,719 be excluded from entry into the United States. These products were laminated cloth, paper or the like, combined with insoluble, infusible condensation products of phenols and formaldehyde. The order of the President prohibiting the importation was contained in T. D. 42801 issued June 11, 1928.

Under the Tariff Act of 1930, practically no changes were made in the provisions of paragraph 28 that concern coal-tar synthetic resins. Paragraph 2 was extended to include, among other things, the resins (polymers) of certain organic compounds. The only commercial products covered by this provision are the vinyl resins. The rate of duty was 30 percent ad valorem on foreign value and 6 cents per pound. Under the trade agreement with Canada, the duty on vinyl acetate, polymerized or unpolymerized, and on synthetic resins made in chief value therefrom was reduced to 15 percent ad valorem and 3 cents per pound (effective Jan. 1, 1936).

The Tariff Act of 1930 contains a provision, in paragraph 11, for synthetic gums and resins not specially provided for, 4 cents per pound and 30 percent ad valorem on foreign value.

Broadening use of synthetic resins.

The application of synthetic resins has extended into practically every branch of industry. This marked expansion is not surprising when the adaptability of these products is considered. Their uses range from jewelry and bottle closures to building materials; from adhesives and new types of surface coatings to light reflectors and shades. They are being substituted for natural materials, such as wood, metal, and glass at an increasing rate. They have provided new uses for raw materials formerly used in antiseptics, disinfectants, explosives, embalming fluids, fertilizers, moth repellants, and as solvents. The speed of expansion of their use in resin manufacture has been such as to create a serious shortage of some of these raw materials.

New applications for synthetic resins appear almost daily. They are used in furniture, wall panels, builders’ hardware, electrical fixtures, and in thousands of small appliances. The automobile industry is probably the largest single user. An interesting application here[5] is in silent gears and shaft bearings where the use of synthetic resins makes water lubrication possible. Other automotive uses are in distributor heads, horn buttons, gear shift knobs, dome light reflectors, control knobs and the finishing lacquers. Additional uses contemplated for the near future are in accelerator pedals and instrument panels. A new type of safety glass in which vinyl resins are used was introduced in 1936.

In decorative uses remarkable progress has been made. Panels of laminated resins are widely used in store fronts, lobbies of office buildings, and hotels; doors faced with this material are in use. The liner Queen Mary is paneled, in part, with laminated resins, as is the annex to the Library of Congress. Lamp shades of urea resin are used in many Pullman cars and are available for home and office use.

Other things being equal, the cheaper a synthetic resin, the more widely it may be applied as a substitute for other materials. As a result many an apparently useless byproduct, such as oat hulls which yield furfural, is either already used or being tested as a source of raw material. Other materials which have already found a place or may do so, are soybean meal, sugar, and certain petroleum distillates.

Each of the important groups of synthetic resins has been sponsored by one or more manufacturers of established reputation and large capital resources. When a product reaches the commercial stage, after heavy research cost, its future importance is therefore usually assured.

Relation of synthetic resins to their raw materials.

Most of the commercially important synthetic resins are derived directly or indirectly from coal. The chart (p. 6) shows the derivation of certain synthetic resins from the principal raw materials used in their manufacture and the intermediate products back to the original source of the material.

The polystyrene resins, for example, are made by polymerizing styrene or vinyl benzene. Although basically from ethylene and benzene, vinyl benzene may be formed in several ways. Ethylene is found in the gases from the destructive distillation of coal but is obtained commercially by cracking natural gas or petroleum. Styrene, found already formed in the light oil fractions from coal tar, causes gum-forming in motor benzol and certain industrial gases.

When coke and lime are mixed and heated in an electric furnace to 2,000° C., calcium carbide is formed. This compound with water yields acetylene, the starting point for a long list of important products, including several types of synthetic resins. When acetylene gas is passed through acetic acid (itself obtained from acetylene) vinyl acetate is obtained. If hydrochloric acid is used instead of acetic acid, vinyl chloride is obtained. These compounds, when polymerized, yield the vinyl resins. The acrylate resins may be obtained from the same basic raw material by an entirely different procedure. Synthetic rubber is also derived from acetylene, as are acetic anhydride and acetic acid (used in making cellulose acetate plastics) and many other chemicals of commercial importance.

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Derivation of certain synthetic resins.

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When naphthalene (from coal tar) is treated with air at elevated temperatures, phthalic anhydride is formed. Substituting benzene for naphthalene yields maleic anhydride. Both of these substances when condensed with glycerin, a byproduct of the soap industry, yield alkyd resins.

The tar acids from coal tar, either separated or mixed, when condensed with formaldehyde give the highly important tar-acid resins. Or if formaldehyde is condensed with urea, obtained from carbon dioxide and ammonia, the urea resins are formed.

The chart indicates the synthetic resins which are thermoplastic, that is, which become plastic again upon reheating, and those which are thermosetting, that is, pass into an infusible stage at a certain critical temperature and pressure and do not again become plastic upon subsequent reheating.

Sources of information.

The data used in this report were obtained from a great variety of sources. The several American and British trade journals were freely consulted as were the various text books on this subject. Much of the information on the domestic industry was obtained by personal contact with producers and by correspondence. Field work included visits to most of the domestic producers of resins and a representative group of fabricators. Information of this type which was nonconfidential or which could be combined so as not to reveal individual operations was invaluable. Even where it was such that it could not be published it became part of the general background.

The data pertaining to the industry in foreign countries were, for the most part, furnished the Tariff Commission by Department of Commerce representatives stationed abroad, in response to inquiries by the Commission.

Growth of the industry.

The coal-tar synthetic resin industry in the United States began on a small scale some years before the World War. The output then was confined to a few types of tar-acid resins and the applications were quite limited until 1927, when certain of the basic patents expired. The output of about 1.5 million pounds in 1921 had increased to more than 13 million pounds in 1927 and the average unit value of sales had dropped from 81 cents per pound to 47 cents. Production continued to increase and the unit value to decrease annually until 1932 when general economic conditions forced a slight curtailment for 1 year. Since then the annual increase in volume and variety has been rapid. Production of non-coal-tar synthetic resins was started on a small scale in 1929 when both urea and vinyl resins entered the picture. Commercial production of the petroleum resins began in 1936 and of the acrylate resins in 1937. Table 1 shows the production and sales of coal-tar resins and of non-coal-tar resins, from 1921 through 1937.

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Table 1.—Synthetic resins: United States production and sales, 1921-37

Many factors have contributed to the growth of the synthetic resin industry. Among these are the intensive research and development work carried on by many individuals and firms; their widespread application in many fields competing with wood, metal, and glass; and the development of processes for raw materials which have greatly reduced their cost and made their wider use possible.

Raw materials.—Although the chief raw materials consumed in the synthetic resin industry are coal-tar derivatives and formaldehyde, many others are utilized. The rapid expansion of the industry has created new demands for materials in increasing quantities and has not only increased the markets for well-known materials but has resulted in the production on a huge scale of materials entirely new to commerce. Practically all the raw materials now used can be derived from a few natural substances, such as air, water, coal, petroleum crudes, salt, sulphur, and limestone. The air yields nitrogen which may be converted to ammonia, a raw material for urea, one of the components of the urea resins. Coal, as is well known, yields a great variety of substances, many of which are essential to synthetic resin manufacture. Benzene is the starting point for synthetic phenol; naphthalene is used to make phthalic anhydride and maleic anhydride; coke is converted to calcium carbide, which in turn yields acetylene, acetic acid, and many other synthetics; carbon monoxide which is converted to methanol and formaldehyde; and the natural tar acids such as phenol, the cresols, and the xylenols. Limestone is a component of calcium carbide, and salt yields needed alkalies and acids. Water is broken down, and the hydrogen is converted to ammonia, methanol, formaldehyde, and ethylene.

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Some idea of the expansion in production of these raw materials whose principal use is in synthetic resins may be had by comparing the output in 1923 of tar acids, formaldehyde, phthalic anhydride, maleic anhydride, urea, vinyl acetate, and vinyl chloride, which amounted to 35 million pounds, with the output of 270 million pounds in 1936. The manufacture of these materials is largely by coal-tar distilling companies and makers of chemicals.

Resins.—The coal-tar resins are the most important in quantity, value, and variety of application. This class includes four groups: (a) tar acid, (b) alkyd, (c) coumarone and indene, and (d) polystyrene. Of these, resins from tar acids (phenol, cresols, and xylenols) are produced in the largest quantity, the output having increased from about 15 million pounds in 1932 to about 80 million pounds in 1937. In the latter year about 40 percent of the consumption of tar acid resins was in molded articles, 25 percent in paint and varnishes, 20 percent in laminated products, and 15 percent in miscellaneous uses.

The alkyd resins have shown a remarkable increase in output. Production totaled slightly less than 10 million pounds in 1933; in 1937 it amounted to about 61 million pounds. Practically all of the alkyds have been consumed in paints and varnishes.

The coumarone and indene resins have increased steadily over a number of years and are now one of the most important groups.

The polystyrene resins have been in an experimental stage for a long time, with the volume of production small. In 1937, however, commercial production of a water-white product was announced, and it is believed that the output of these resins will increase sharply in the near future.

The non-coal-tar resins were of little importance prior to 1930 and production amounted to less than 2 million pounds in 1932. Since then, however, progress has been rapid, both in types and output. Resins from urea constitute an important part of this class and the output has increased practically every year since 1929 when production was started. Most of the output is used in molded articles where light and pastel shades are required. In 1936, for the first time, appreciable quantities were consumed in laminating and in surface coatings.

The vinyl resins have been produced in increasing quantities for the past 8 years. Production reached a new high in 1937, and with the acceptance of this type of resin for safety glass laminations it is expected that the output will increase materially in the near future. In 1937 the application in surface coatings, molded articles, and laminations were of approximately equal importance.

The acrylate resins are among the newest commercial developments in this industry. Of the several types now manufactured, one appears valuable in surface coatings and adhesives and another, in the form of its cast or molded polymer, in airplane windows, machined articles, and lenses.

Petroleum resins were first produced in commercial quantities in 1936, but the output in that year was appreciable. These low-priced synthetics are used in surface coatings, laminations, and miscellaneous uses.

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The industry abroad.

World production of synthetic resins at this time is estimated at 300 million pounds annually, of which the United States accounts for 45 percent. Germany produces about 27 percent and Great Britain about 20 percent of the total and a number of countries including France, Italy, Czechoslovakia, Canada, and Japan produce the remainder. Practically all types are made in Germany and Great Britain although in lesser quantities than here. The urea resins originated abroad, as did the acrylates and polystyrenes.

Commercial development of the synthetic resins abroad has been somewhat behind that in the United States, although in recent years the increase there has been so rapid as to seriously affect the international raw material market. Germany, formerly one of our principal sources of crude naphthalene, for a time restricted exports of that commodity in order to conserve the available supply for home consumption, presumably in alkyd resins. Great Britain, formerly the principal exporter of phenol, has found it necessary to supplement production of natural phenol with synthetic phenol. It is possible that in the future similar conditions may arise in world markets for cresylic acid.

International trade.

International trade in the synthetic resins has been small. Germany has been the principal exporting country. There are a number of reasons for the negligible movement of these materials in international trade, the chief of which are active home markets in the principal producing countries; the existence of patents of a basic nature which limited trade to the owners and licencees under them; affiliation of producing companies in different countries with allocation of the world market; and high tariff barriers in many countries.

The principal domestic producer of tar-acid resins is affiliated with firms in Germany, the United Kingdom, France, Italy, Canada, and Japan. The two principal American makers of urea resins have or have had agreements as to patents, exchange of technical information, and probably markets, with producers in Great Britain. Similar conditions exist with other types of resins.

In 1937 production of all synthetic resins in the United States amounted to 162 million pounds and imports to less than 674,000 pounds (see table 13, p. 58). Production of tar-acid resins in that year amounted to 79.8 million pounds; alkyd resins to 61.2 million pounds and all coal-tar resins to 141 million pounds. Imports of all coal-tar synthetic resins (which would include both tar acid and alkyd as well as others) amounted to only 19,000 pounds. Coal-tar resins are dutiable at 7 cents per pound and 45 percent ad valorem based on American selling price. On the small imports in 1937 the duty collected averaged 54 percent ad valorem on American selling price and would have averaged much higher had it been calculated upon foreign value as are most duties.

In 1937 the production of non-coal-tar resins totaled about 21 million pounds. In that year imports of non-coal-tar resins totaled 65,000 pounds. Imports of non-coal-tar resins, other than vinyl resins, amounted to less than 2,000 pounds. These were dutiable at[11] 4 cents per pound and 30 percent ad valorem on foreign value, equivalent on the average to 48 percent ad valorem. The vinyl resins have been imported into the United States in increasing quantities in recent years. The principal foreign producer, in Canada, developed markets in the United States, but is a joint owner of a plant now under construction in this country. Imports of vinyl resins in 1937 were 653,000 pounds. These were dutiable at 3 cents per pound and 15 percent ad valorem on foreign value, equivalent to 25 percent ad valorem.

It is apparent that foreign competition with United States producers in the home market has been and is likely to continue insignificant under existing duties. With a large home market and generally favorable conditions with respect to the necessary raw materials and the technical skills, this situation would probably continue even under lower duties. Moreover, as international trade develops in these materials, this country is more likely to be a net exporter than a net importer.

The tar-acid resins were the first true synthetic resins to appear in commerce, but they were preceded by two plastics, celluloid and casein. Probably the first successful attempt to make a semisynthetic or modified natural product as a substitute for natural materials was the discovery of celluloid in 1868 by John Wesley Hyatt. By treating cotton with nitric acid he obtained a material which could be substituted for ivory in billiard balls. The Celluloid Corporation grew out of this discovery and the product was widely used to replace amber, ivory, mother-of-pearl, tortoise shell and other materials.

The discovery of casein plastic took place in 1890. Adolph Spitteler of Hamburg, Germany, in trying to make a white blackboard, found that casein (from milk) could be hardened by treating it with formaldehyde. Casein plastics are now widely used in buttons, buckles, and other ornaments.

As early as 1872 the reactions between coal-tar acids and aldehydes were being studied, and by 1900 many research workers were investigating phenol-formaldehyde condensation products. During the period 1900-1910, the study of these products increased greatly, both with regard to process of production and to applications, such as its substitution for shellac and other natural resins. United States Patents Nos. 942,699 and 942,809 issued December 7, 1909, to Dr. L. H. Baekeland and commonly known as the heat and pressure patents were probably the basic patents on phenol-formaldehyde resins. Baekeland so modified these resins by methods of hardening under heat and pressure that rigid molded articles could be made. The range of uses of tar-acid-formaldehyde molding compositions has steadily widened. Molded articles such as pencil and pen barrels, ash trays, bottle closures, parts for automobiles, cameras, precision instruments, dynamos, motors, and other electrical equipment, cafeteria trays, table and counter tops are well known to the public.

During the life of these and other basic patents issued about 1909 the domestic production of phenol-formaldehyde molding compositions[12] was practically restricted to one company. Since the expiration of these patents in 1926 a number of other producers have been established. In 1937 there were 36 domestic makers of tar-acid-formaldehyde resins for molding, laminating, and surface coating applications.

The early work done on phenol-formaldehyde resins gave dark-colored products which were too hard and brittle to be machined or worked on a lathe. Investigations by F. Pollak and A. Ostersetzer, in Vienna, resulted in a process for the manufacture of cast phenolic resin with a range of color possibilities from water-white transparency through all shades and degrees of translucency and opaqueness. This product is cast into sheets, rods, tubes, and special castings, all of which may be turned or milled on automatic machines. United States Patent No. 1,854,600, issued April 19, 1932, to F. Pollak and A. Ostersetzer and assigned to Pollopas, Ltd., London, is considered the basic patent for cast phenolic resins. American rights under this and related patents are owned by the Catalin Corporation of America who have licensed other domestic makers. The German equivalent of rights under this patent is owned by a subsidiary of I. G. Farbenindustrie Aktiengesellschaft and rights under the French equivalent by Établissements Kuhlmann.

In the early days of the phenol-formaldehyde resin industry (1909-16) there was considerable uneasiness about the supply of phenol. World production was not large and Germany and England controlled most of it. The output of the United States was almost entirely for medicinal use, although our potential production was large (see p. 111). This situation caused many research workers to study the resins made from other tar acids, principally meta and para cresols and the xylenols. The investigations resulted in many new types of resins and in modifications of the phenol-formaldehyde type. The World War changed conditions materially. Imports of phenol were shut off and prices soared. Production of synthetic phenol was begun, and, although the wartime production went into explosives, its development had an important bearing on the synthetic resin industry. Unusual demand for phenol, toluene, and other coal-tar crudes resulted in a great expansion of production. With the cessation of hostilities there was an ample supply of cheap phenol and the expansion of the coal-tar industry continued so that the supply of tar acids kept pace with the new demand for use in the production of synthetic resin.

In 1926, the early patents on resins from tar acids began to expire and the second era of the industry began. Since that year most of the research work has been for materials that would give different properties to the resultant resins. The past 10 years have seen a greater diversification in the manufacture of resins from tar acids and substantial reductions in their prices. Tar-acid resins averaged $1.29 per pound in 1920, 23 cents per pound in 1934, and 19 cents per pound in 1937. The production of certain resins of this class which are soluble in drying oils has been an important achievement. They yield varnishes of improved type that are quick-drying.

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The three stages of a tar-acid resin.

About 28 years ago the Journal of Industrial and Engineering Chemistry published the original paper of Dr. Leo H. Baekeland on the Synthesis, Constitution, and Uses of Bakelite. According to Baekeland’s theory, the reaction between phenol and formaldehyde consists of condensation and polymerization taking place in three stages. The first product formed, called “initial condensation product A” is usually a liquid or semisolid which on continued heating is converted to “intermediate condensation product B.” B is an insoluble solid which can be softened by heat, and is the material used by molders, laminators, and other fabricators.

The final stage, known as “final condensation product C,” is probably the result of polymerization of B, by heat and pressure. C product is infusible, indifferent to all solvents, and cannot be distilled or melted; hence the tar-acid resins belong to the thermosetting group. The conversion to C takes place in the presses of the molder or final fabricator of the resin. This theory is generally accepted and the designations of the several stages are in universal use in the trade.

Classification of tar-acid resins.

All the synthetic resins obtained by the condensation of a tar acid, or a mixture of tar acids, with an aldehyde are popularly called phenolic resins, regardless of whether they are made from phenol, the isomeric cresols, xylenols, other high boiling tar acids, or any mixture of these materials. A more accurate designation and that used in this survey is tar-acid resins, reserving the term phenolic resins for those made from pure phenol.

The tar-acid resins might be classified in a number of ways; for example, by composition, physical form, or general application. Each of these has its shortcomings. To classify them by composition, that is, by the kind of tar acid used, is not satisfactory because of the vast number of types made from mixed tar acids. For the purpose of this discussion it seems best to classify the tar-acid resins by their general application into six groups: for molding, for casting, for laminating, for surface coating (paints, varnishes, and lacquers), for adhesives, and for miscellaneous uses.

In 1937 approximately 66 percent of the United States production of tar-acid resins was made from phenol; 18 percent from phenol-cresol mixtures; 13 percent from cresol-cresylic acid mixtures; and 3 percent from cresol-xylenol mixtures. Table 2 shows for recent years production and sales of tar-acid resins by type of raw material. Pure phenol is used for cast resins. Molding resins are usually made from pure phenol or from tar-acid mixtures, chiefly phenol. Laminating and coating resins are usually made from mixtures containing substantial amounts of the cresols and xylenols (frequently spoken of by the trade as cresylic acid).

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Table 2.—Tar-acid resins: United States production and sales, by type of raw material, 1933-37

Processes of resin manufacture.

The processes of and patents for the manufacture of tar-acid-formaldehyde resins are numerous. No attempt is made here to describe in detail the several processes of manufacture or the endless number of variations and modifications. In general the processes in operation may be designated (a) one stage wet, (b) two stage wet, and (c) dry.

The one-stage wet process consists in heating molecular proportions of tar acid and formaldehyde (40-percent solution) in the presence of an acid or alkaline catalyst. The formaldehyde is added all at once and the reaction proceeds with the elimination of water. The difficulty with this process is that of obtaining uniform batches because it cannot be controlled exactly.

The two-stage process is probably the one most widely used today and consists in introducing formaldehyde in two or more stages as the reaction progresses. Much better process control and more uniform results are so obtained. A soluble, fusible resin is formed from which the water is easily removed. Fillers and pigments may be added during the latter part of the operation.

The dry process is the least important and is used only where cast resins are being made. Light-colored, transparent resins are obtained and the operation is carried on to the final stage (C resin). In this process the aldehyde used is solid paraformaldehyde or hexamethylenetetramine. These materials are more costly than formaldehyde solution.

Proportions of raw materials used vary widely—Baekeland suggested 7 mols of formaldehyde and 6 mols of phenol (210 parts of 100-percent formaldehyde to 564 parts of phenol), with a yield of[15] resin equivalent to 118 percent of the phenol. Larger proportions of formaldehyde are said to increase the yield to as much as 140 percent of the phenol.

Catalysts used to aid in the condensation of the reacting bodies may be acids or bases. Certain properties of the resins may be varied by the kind and quantity of catalyst used. Large proportions of basic or acidic catalysts may affect the filler or metal inserts. Basic catalysts used include caustic soda, caustic potash, ammonia, carbonates, and alkali sulphites. Acid catalysts are usually one of the mineral acids such as hydrochloric acid or sulphuric acid.

While formaldehyde in the form of a 40-percent solution is the principal aldehyde used with the tar acids, certain other aldehydes are used in small amounts. Among these are acetaldehyde, butyraldehyde, benzaldehyde, and others. Resins from furfural and phenol are discussed as “Furfural Resins,” page 51.

Production in the United States.

The production of tar-acid resins in the United States has increased markedly in the last 10 years. Table 3 shows the production and sales of all coal-tar resins in 1927 and 1928 (when there was no further break-down available but when this classification was made up chiefly of tar-acid resins) and of tar-acid resins from 1929 to 1937. The figures given are in net resin content and do not include fillers, modifiers, or pigments. From 1929 to 1937 production increased from 26 million pounds to 80 million pounds; sales from 25 million pounds valued at 9.9 million dollars to 74 million pounds valued at 13.3 million dollars; the value per pound dropped from 39 cents to 19 cents.

In 1937 the production of tar-acid resins for molding accounted for about 40 percent of the total; those for surface coatings, about 25 percent; those for lamination, about 20 percent; and those for miscellaneous uses, about 15 percent.

Table 3. Tar-acid resins: United States production and sales 1927-37

[16]

Imports into the United States.

Imports of tar-acid resins into the United States are dutiable under paragraph 28 at 7 cents per pound and 45 percent ad valorem based upon American selling price. Discussion of this rate, other restrictions upon imports in the earlier years, and of the rates upon articles made of these resins will be found on pages 59 to 61.

Imports of tar-acid resins are not shown separately in official statistics; the classification under which such imports are entered includes all synthetic resins of coal-tar origin. Table 4 shows the quantity and value of imports of all coal-tar resins since 1918, and table 5 shows the principal sources of imports for certain years.

Invoice analyses of imports in the last 3 years show only very small quantities of phenolic resins being imported. In 1934 there was an importation of 950 pounds of Bakelite molding compound; in 1935 imports of 100 pounds of molding compound and 22 pounds of aminophenol resin are recorded, and in 1936 imports of Bakelite filament compound totaled 250 pounds and other resins 8,851 pounds.

Even if in the years up to 1933 all of the imports of resins of coal-tar origin were tar-acid resins, imports of tar-acid resins have been negligible when compared with production. The smallness of imports may be accounted for by a combination of factors, (1) the prohibition of imports of certain types, which conflicted with patent rights; (2) the rate of duty upon imports; (3) the fact that the manufacture of tar-acid resins developed more rapidly in the United States than in most foreign countries; and (4) the allocation of markets through agreements between affiliated producers in different countries. (See p. 58.)

Table 4.—Synthetic resins of coal-tar origin: United States imports for consumption, 1919-37

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Table 5.—Synthetic resins of coal-tar origin: United States imports for consumption, by principal sources, in specified years, 1929-37

Exports from the United States.

Appreciable quantities of phenolic resins are exported annually in the form of molding compounds and as finished articles of wide variety. Statistics of these exports are not compiled separately by the Department of Commerce.

Exportation is limited by a number of factors, such as licensing agreements, patents, allocation of markets, and high tariffs or embargoes in certain countries. The largest domestic maker is affiliated with producers in Great Britain, Germany, France, Italy, Canada, and Japan. Other domestic firms have agreements as to patents and markets with producers in England, Germany, and other countries.

[18]

TAR-ACID RESINS FOR MOLDING

The tar-acid resins were first developed for molding and they are still used in large volume in this way. An article produced in large quantity is more likely to be made of molded resin. The cost of the mold, which may amount to several thousand dollars, then becomes very small per unit produced. If the article is of such a shape that it would require a great deal of labor to produce in metal or wood, it may be produced in quantity much more cheaply from resin, since it will come from the mold almost in finished form.

A few of the large molders find it economical to make their own resins when they use one type in large volume or desire some special modification. Most of the molders buy resins for molding in the form of either powder or pre-formed pellets ready for use.

Molding powders and pellets.

Molding powder is made from B-stage resin (see p. 13), a filler, a pigment, a lubricant, and a plasticizer. These materials are mixed and put through rolls at a moderate heat and pressure. The resin softens and amalgamates with the other materials. It hardens upon cooling and is ground to powder. A pre-formed pellet may be made from the powder by pressure; use in this form saves the time of the molder when filling the mold, since he is not required to measure the powder.

The proper selection of the filler in a molding powder is important in influencing the quality of the molded article. Fibrous fillers improve the mechanical strength and shock resistance of the finished article. Wood flour is the most widely used filler in tar-acid resins as well as in other thermosetting resins. Pine, spruce, and fir are the principal kinds used, and consideration must be given to the bulk, gum content, color, and the size and shape of the wood particles. Color is the least important since most of the tar-acid resins give brown or black moldings. When the molding must withstand high temperatures, asbestos fiber is used as a filler. In articles requiring high shock resistance, such as golf club heads, a filler of paper pulp is used. Where high electrical insulation and dielectric properties are required, ground mica is used as the filler. Certain inorganic fillers such as powdered slate, gypsum, barium sulphate, calcium sulphate, china clay, zinc oxide, and infusorial earths, are sometimes used. Large proportions of these may be used where hardness is more important than strength, as in phonograph records. Other materials used include rubber, graphite, horn, bone, starch, pumice, and cork.

Coloring matter used may be coal-tar dyes or pigments such as bone black, carbon black, and iron oxides. Pigments are usually more satisfactory, although dyes are sometimes preferred in articles for insulation.

A lubricant is added to the molding mixture to overcome the tendency to stick in the mold. Metallic soaps, stearates, and stearic acid are those most commonly used.

Sometimes a plasticizer is included, its function being to act as a solvent for the resin, thus increasing the flow of the material in the mold. The plasticizer should be one which will become infusible or at least remain solid in the molded article.

Preform Press Making Pellets for Use in Molding.

Source: Bakelite Corporation, 247 Park Avenue, New York, N. Y.

Vacuum Cleaner Parts of Tar-Acid Resin Illustrating the Intricate Molded Shapes Possible.

Source: Bakelite Corporation, 247 Park Avenue, New York, N. Y.

Radio Cabinet and Telephone Set of Molded Tar-Acid Resin.

Source: Bakelite Corporation, 217 Park Avenue, New York, N. Y.

[19]

A typical molding powder or pre-form pellet will contain by weight:

The molding of tar-acid resins.

Ordinarily the molds used are made of hardened steel, highly polished. They must stand working pressures of several thousand pounds per square inch. The mold is placed in a hydraulic press, heated by steam, electricity, or gas, and the molding material is placed in the mold. The press is closed and heat and pressure are applied. The temperatures used range between 250° F. and 365° F., and the pressures between 1,000 and 8,000 pounds per square inch. The molding time depends on the shape and size of the article and on the composition of the molding material. As little as one-half minute is required for small objects and as long as 10 minutes for large objects. Average molding time is about 3 minutes. The article is removed from the mold, allowed to cool, and is then trimmed, sanded, filed, or polished. Since the mold is highly polished, the finishing operation is usually needed only to remove the flash. Inserts, such as metal parts (binding posts, electrical contacts, etc.), or inlays of polished metal in name plates, and signs, are often molded in; gear shift knobs are molded over a hollow metal core; rubber inserts are used in castors, electrical plugs, and similar objects.

The molding operation is an art, and has made remarkable progress in recent years. Many articles molded of tar-acid resins are well-known to the public. The automotive industry is the best customer, using such molded parts as gear shift knobs, horn buttons, accelerator pedals, light switches, ignition parts, and distributor heads. Other well-known applications are builders’ hardware, electrical switch plates, switches and fixtures, fountain pens, radio parts, telephone parts, handles for stoves, vacuum cleaners, and other appliances, buttons, buckles, costume jewelry, camera cases, radio cabinets, small containers, and hundreds of others.

The importance of tar-acid resins in molded articles is shown by the fact that more than 75 percent of all synthetic resin molded articles made in 1937 used this type of resin as a binder.

Production of tar-acid molding resins.

Domestic production of tar-acid molding powders and pellets was reported to the Tariff Commission by 15 makers in 1937. Most of these firms have specialized in resin development and manufacture. Among the well-known brands are Bakelite, Durez, Durite, Resinox, Indur, and others (see p. 153 for list of trade names).

Statistics of production and sales of tar-acid resins used in molding were collected separately for the first time in 1935. They show a net resin output of about 21,000,000 pounds, with sales of 18,000,000 pounds or about 40 percent of the total tar-acid resins. The average unit value was 17 cents per pound. In 1937 the production of tar-acid resins for molding exceeded 32,000,000 pounds, again about 40 percent of the total. These statistics are based on net resin and do not include fillers, modifiers, pigments, or inert material of any kind.

[20]

CAST PHENOLIC RESINS

Process of manufacture.

The production of cast phenolic resins requires pure materials, expensive equipment, and extreme care in the control of the operation. A mixture of phenol and formaldehyde and a catalyst (usually sodium or potassium hydroxide) is charged into a nickel-lined reaction kettle and heated until the water separates and is removed. The reaction is then allowed to proceed to the desired point. Glycerin is added to aid in forming a transparent product. All equipment, including pipe lines, valves, and pumps, is nickel or nickel lined except that used for formaldehyde, which is made of aluminum.

The resin is usually made in 1,000 pound batches, and the reaction cycle ranges from 6 to 18 hours. It is colored with soluble coal-tar dyes and cast into lead molds. These are placed in a heated room and allowed to cure for 3 to 6 days. The resin is removed from the mold with air hammers, and the lead molds are melted.

The appearance of the resin may be changed by varying its water content, by the addition of dyes and fillers, and by the addition of other substances to produce some desired effect, such as imitation ivory or marble. The clarity of the resin depends upon its water content—the greater the degree of dehydration the clearer the product. Range of colors is complete, from crystal clear to the darker shades, with any degree of transparency, translucency, or opaqueness.

Casting is in the form of sheets, rods, tubes, or special forms suitable for the production of buckles, jewelry, and other small products. Molds of complicated shape cannot be used, which means that most articles if produced of cast resin must be produced from standard shapes by subsequent working. Recently small radio cabinets have been cast.

Uses.

Cast phenolic resin can be machined in the same manner as hard wood. It must be polished after machining, usually by tumbling with shoe pegs and pumice or with muslin wheels. The smooth finish and low degree of heat conduction give the material a pleasant feel, not cold to the touch as is metal. The coloring is not superficial and therefore does not chip or wear off. Electrical properties are excellent. A slow polymerization continues for some time after fabrication, resulting in slight shrinkage.

Cast phenolic resins are marketed by the producers as rods, sheets, cylinders, and special castings. Standard round rods range from ⅜ inch to more than 5 inches in diameter. Special rods are available in such forms as square, hexagon, octagon, and fluted. Standard sheets are in sizes from 12 by 24 inches to 36 by 72 inches, and from ⅛ to 1 inch thick. Stock cylinders are available in a wide range of inside and outside diameters.

Cast Phenolic Resins, Standard Shapes and Small Articles Fabricated From Them.

Source: Bakelite Corporation, 247 Park Avenue, New York, N. Y.

Stock material is fabricated by a number of firms into an endless variety of articles. Among these are toilet articles such as combs, backs for brushes, cosmetic containers, and trinkets; fittings for automobiles, electrical appliances, furniture, and display fixtures; jewelry, dress ornaments, clock cases, handbag frames, vanity cases, smokers’ articles, signs and advertising specialties, picture frames, handles for cutlery, chessmen, pens, desk penholders, pencils, and[21] many others. Probably the largest consumption is in the making of buttons and buckles.

The cast phenolic resins are odorless, tasteless, nonflammable, resistant to oils and greases, and practically nonbreakable.

Patents and licensing.

The basic patent covering the manufacture of cast phenolic resins is United States Patent No. 1,854,600, issued April 19, 1932, to F. Poliak and A. Ostersetzer, of Vienna, and assigned to Pollopas, Ltd., of London. Many other patents have been granted on variations and modifications of this one. The basic process is also patented in England, France, Germany, and other countries.

United States and Canadian patent rights were purchased by the American Catalin Corporation; German rights by the Interessen Gemeinschaft Industrie A. G. (German I. G.); French rights by Kuhlmann Co., and British rights by the Imperial Chemical Industries. These licensing arrangements limited the licensee to sales in his own and, in some instances, nearby countries.

The American Catalin Corporation has successfully defended the validity of this patent and has licensed a number of domestic manufacturers to produce cast phenolic resins on a royalty basis.

In 1937 there were seven domestic makers of cast phenolic resins located in New Jersey, New York, Massachusetts, and Pennsylvania. These firms produce and market resins under the following trade names: Catalin, Prystal, Joanite, Fiberlon, Phenolin, and Marblette.

Production of cast phenolic resins.

Production was initiated about 1929 by the American Catalin Corporation. The output increased substantially every year from that year through 1933. Statistics of production and sales are not publishable for the years prior to 1934 because they would reveal the operations of individual firms; they are given in table 6 for subsequent years.

Table 6.—Cast phenolic resins: United States production and sales, 1934-37

Imports and exports.

The licensing agreements, as outlined above, provide for the allocation of markets for cast phenolic resins. Because of this arrangement there are little or no imports and exports of this material.

TAR-ACID RESINS FOR LAMINATING

By laminating is meant the impregnation of sheets of paper, fiber, or cloth with a solution of synthetic resin and the building up of[22] these layers into sheets of reinforced synthetic resin of various thicknesses. When a tar-acid resin is used the paper or cloth is immersed in or coated with a solution of the B-stage resin, dried, and layers of the material are compressed and consolidated, under heat and pressure to form sheets, rods, tubes, blocks, and other forms, in the infusible C-stage.

The coating of sheets of paper with solutions of natural resin and the compacting of these sheets by heat and pressure is an old practice, especially for electrical uses. Shellac and copal have been widely used and yield a laminated board of good electrical and mechanical properties when used at temperatures under 70° C. Above 70° C. the resin softens and the desirable properties are lost. Since temperatures above 70° C. are not uncommon in electrical equipment, the limitations of these natural resins in this use can readily be seen. The use of tar-acid resins to impregnate insulation material removes the temperature limitation and otherwise improves the product; insulators so made are widely used in all sorts of electrical and radio equipment.

Uses of tar-acid resin laminated products.

Laminated sheets of tar-acid resin are made with paper, canvas, duck, linen, pulpboard, vulcanized fiber, plywood, and other materials. Paper is the material generally used for electrical insulation, although cloth is sometimes used when greater strength is needed. Canvas is used where maximum strength is required, as in gears for automobiles and industrial machinery. Impregnated linen is adapted to punched parts and small gears.

These laminated materials are uniformly dense, tough, resilient and light in weight. They are nonabsorptive, have low thermal conductivity, and a low coefficient of expansion. Their dielectric strength is excellent and chemically they are inert to oils, brine, most acids, weak alkalies, and many solvents. Structurally they are strong under tension, compression, flexion, or impact; they are easy to machine and are sound absorbing.

Gears made of laminated canvas are widely used; they are silent and outwear those made of metal. The development of such gears was brought about by the demand for a positive drive without the clash and clatter resulting from metal to metal contact. The laminated gear absorbs vibrations, eliminates noise, and reduces wear. The laminated material is one-seventh the weight of brass, one-sixth the weight of steel, one-fifth the weight of cast iron and one-half the weight of aluminum. Laminated gear blanks may be cut on automatic machines into helical, spur, bevel, or worm gears.

Timing gears in automobiles are frequently of this type; they require no adjustment and seldom need replacement during the life of the motor. The light weight of the material reduces to a minimum flywheel effect on the camshaft. Where lubrication is difficult a graphite impregnated blank may be used.

Bearings made from laminated fabric are successfully used in heavy rolling mills where they reduce replacement costs and decrease power consumption. The laminated material possesses strength, smooth surface, density, good load carrying capacity, high impact resistance, nonscoring properties, and is practically frictionless. Power consumption is said to be reduced as much as 40 to[23] 60 percent of that of metal bearings and the life of the laminated bearing has been as much as 10 times that of the metal ones. It replaces Babbitt metal, brass, bronze, white metal, gun metal, or lignum vitae in this application.

Laminating Sheet Press.

Source: Bakelite Corporation, 247 Park Avenue, New York, N. Y.

Gears Made of Laminated Tar-Acid Resin.

Source: Bakelite Corporation, 247 Park Avenue, New York, N. Y.

Cocktail Lounge Using Tar-Acid Laminated Decorative Material.

Source: Bakelite Corporation, 247 Park Avenue, New York, N. Y.

In decorative uses, laminated materials have made remarkable progress in recent years. In this application the material made from laminated paper is veneered on wood or fiber board, and the surface is so durable that refinishing is probably not necessary during the life of the equipment. Table tops for public rooms such as restaurants, cafeterias, and bars are widely used because of the beautiful designs obtainable and because the material is not discolored by lighted cigarettes, alcohol or other liquids, and does not chip or crack. Laminated sheets are used for bathroom and kitchen walls, doors, window sills, store and theater fronts, lobby walls in hotel and office buildings, and counter tops in banks and post offices. The liner Queen Mary is equipped with panels of this material as is also the new Library of Congress Annex. Most of the leading hotels have installed bar and cocktail lounges of laminated materials because of the range of color and the ease with which novel designs may be carried out.

Almost any solid color, design, or imitation of another material may be given the laminated sheet simply by printing it upon the top sheet of paper used in the impregnated assembly. Thus a beautiful piece of walnut or mahogany may be photographed, inexpensively reproduced upon paper, and the finished laminated sheet will closely imitate the polished wood. The combination of beauty with long life should permit the widespread use of this type of material in all sorts of building and equipment. It has been suggested as a possibility in automobile body construction.

Other important uses are in trim and door strips for mechanical refrigerators, in cafeteria trays, buckets and special containers, tires for factory trucks, textile spools, miners’ safety helmets, gaskets, valve discs and rings for pumps, pulleys, besides many others.

Production of tar-acid resins for laminating.

Statistics of production and sales of synthetic resins for laminating were not separately compiled prior to 1935. Since that year the resins made from cresylic acid have been used to the greatest extent in laminating, followed by those made from phenol. Tar-acid resins reported as “used in paints, varnishes, and lacquers” may include appreciable quantities of resin varnishes used for laminating. The total production and sale in 1937 of tar-acid resins used in laminating, therefore, would be the sum of the 20 percent of the total (see table 3) reported for laminating plus some part of the 25 percent reported for surface coatings.

Domestic producers of tar-acid resins for laminating are located in Delaware, New Jersey, New York, Illinois, Massachusetts, and Pennsylvania. The makers of the laminated materials are located in Delaware, New Jersey, New York, Ohio, Illinois, Pennsylvania, Indiana, and Connecticut. Their products are marketed under a number of trade names, including Micarta, Dilecto, Celoron, Formica, Textolite, Phenolite, Insurok, Spauldite, Synthane and Phenol Fibre.

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Imports into the United States.

There has been practically no importation of synthetic resins for laminating. Imports of laminated products (rods, tubes, blocks, strips, blanks, or other forms) of which synthetic resin is the chief binding agent totaled only 215 pounds, valued at $612 in 1931 (principally from the United Kingdom); 13 pounds, valued at $71 in 1932; none in 1933 and 1934; 609 pounds, valued at $579 in 1935 from Canada, Germany, and the Netherlands; and 3,260 pounds, valued at $9,468 in 1936 from Austria, Germany, and the United Kingdom.

Exports from the United States.

Exports of phenolic or other synthetic resins for laminating and of laminated articles are not separately recorded in official statistics. It is known that appreciable quantities of laminated articles are exported to Canada, England, and other countries.

TAR-ACID RESINS FOR SURFACE COATINGS

Synthetic resins are widely used for surface coatings, chiefly because of the ease with which new types can be produced to meet special requirements and because of their uniformity. Tar-acid resin coatings may be varied in composition and properties to meet a particular purpose. Possible variations depend on the type or mixture of tar acid used (phenol, cresols, xylenols, tertiary amyl phenol, tertiary butyl phenol, phenyl phenol), whether the condensation takes place in the presence of an acid or an alkali, and on the proportion of formaldehyde used. The resin so formed may be modified with natural resins, synthetic resins of the alkyd type, fatty acids, or other materials. The almost endless opportunities for different types can, therefore, readily be appreciated.

Types of resin used and the resultant coatings.

The tar-acid resins used in varnishes and other surface coatings are usually oil-soluble types. They may be divided into three general classes: (1) Phenol-formaldehyde condensation products rendered oil-soluble by chemical combination or physical dispersion in other materials, such as rosin and copal; (2) condensation products made from tar acids other than simple phenol, which are themselves soluble in drying oils and thinners; and (3) products from the condensation of the substituted phenols and formaldehyde. These three classes of oil-soluble tar-acid resins differ widely in their chemical and physical properties and in their functions. The first group are usually called modified phenolic resins, the second group are referred to as unmodified or 100-percent soluble, and the third group are known as substituted phenolic resins.

The unmodified resins are extensively used in long-oil tung varnishes, to which they impart greater drying speed, durability, and resistance to alkalis and gases. The modified types impart the same properties to tung oil varnishes but to a lesser extent. In addition the modified types possess considerable hardness so that greater gloss and fullness are obtained. Modifiers are either drying oils or natural resins; tung oil is the most widely used oil and rosin the principal natural resin. Substituted phenols such as para tertiary amyl phenol and para tertiary butyl phenol may be used in place of simple phenol; while these are relatively high priced components, the resins[25] made therefrom have increased in recent years to an appreciable volume because of their improved properties.

Other synthetic resins, such as those of the alkyd, petroleum, urea, and vinyl types, are sometimes incorporated with the phenolics in the same surface coating to obtain some desired property. The addition of a plasticizer, such as tricresyl phosphate or dibutyl phthalate, improves the flexibility of the film.

Spirit varnishes, in which the synthetic resin is dissolved in a solvent, are also available. In this type the soluble fusible resin (form A) is dissolved in an organic solvent such as acetone or the various alcohols, and conversion of the resin to the insoluble, infusible state (form C) is effected by baking the film.

Coatings made from tar-acid resins are widely used in so-called 4-hour enamels and varnishes, for both interior and exterior application. They are also used in the manufacture of linoleum, artificial leather, adhesives, and printing inks. When incorporated with nitrocellulose or cellulose acetate lacquers they improve the adhesion, luster, and resistance to alkalies.

Production in the United States.

In 1937 the output of tar-acid resins for surface coatings exceeded 20 million pounds (net resin). Those from phenol and the substituted phenols accounted for a very large part of the total. They were followed by resins from cresylic acids and the xylenols in that order.

In 1937 there were about 20 domestic makers of this type of synthetic resin, with factories located in California, Connecticut, Illinois, Indiana, New Jersey, New York, Massachusetts, Michigan, Missouri, Ohio, Pennsylvania, and Rhode Island.

Imports into and exports from the United States.

Imports of oil-soluble phenolic resins have been negligible. This is due, in part, to licenses and agreements between certain domestic and foreign makers, to the remarkable advancement and pioneering work done in this country, to the holding of many basic patents by Americans, and to the relatively high duty on imports.

Exports of these products, usually in the form of enamels, varnishes, and lacquers, have been appreciable and are probably increasing each year. Official statistics are not reported separately.

TAR-ACID RESINS IN ADHESIVES

A comparatively new use for tar-acid resins is in the manufacture of wood adhesives. Ordinary vegetable and animal glues have long been used, although their deficiencies in certain characteristics are well known. These include (a) their inability to produce uniform products, (b) the tendency of most alkaline glues to stain wood, (c) the bad effects of moisture on them, and of bacteria and fungi in the case of animal glues. The tar-acid resins have none of these objectionable qualities. Being chemically inert they are free from attack by fungi and bacteria. Moisture does not affect them, and they do not stain wood.

Three types of resins are used as wood adhesives, principally in bonding plywoods and veneers: (1) Hot press liquid, (2) cold press liquid, and (3) resin film. Furniture, radio cabinets, games, and[26] building products constructed from plywoods bonded with resins can be shipped to tropical countries, the bond not being affected by extreme climatic conditions.

These resin adhesives are more expensive than the usual animal and vegetable glues, a factor which has limited their application. Their advantages may, however, open up to resin bonded plywoods uses in which the more ordinary types are not satisfactory.

TAR-ACID RESINS FOR OTHER USES

The application of tar-acid resins in casting, molding, laminating, surface coatings, and adhesives has been described. There are many other uses, but most of them approach the types of application dealt with.

Impregnation of all sorts of materials with tar-acid resins is an increasing use; such applications are in fabrics for aircraft, crease resistant textiles, wood, asbestos, concrete, and electrical coils. Wood with resin forced into the fiber under pressure is used for furniture, flooring, heads for golf clubs, and handles for utensils. Resin is used as a binder in the manufacture of brake linings for automobiles, as well as in the manufacture of abrasive and grinding wheels.

An interesting application is in the construction of corrosion-resistant chemical plant equipment. In 1922 the German firm of Saureschutz Gesellschaft was incorporated to fabricate equipment composed of a special acid-resisting type of phenolic resin and asbestos. Sometime later its manufacture was started in the United States. All sorts of industrial plant equipment is now available, including cylindrical and rectangular tanks up to 9 feet in diameter and 12 feet high, piping for corrosive liquids and gases, valves, pumps, fans and ventilators, filter press plates and frames, buckets, dippers, etc.

Another new use is for making matrices in which to mold rubber printing plates. Such plates are used at present chiefly in printing cotton and paper bags but extensive experimentation promises to broaden their use. The matrix is made of fiber board of very open structure impregnated with tar-acid resin in the process of manufacture.

Description and uses.

The alkyd resins, used principally in paints, varnishes, and lacquers, are a group of condensation products synthesized by reacting polyhydric alcohols, such as glycerin and the glycols, with dibasic organic acids, such as phthalic, maleic, succinic, and sebacic. The condensation product is almost always modified to give properties to the resin desirable or essential to the specific application contemplated. The modifying agent may be a drying, semidrying, or nondrying oil; the fatty acid of an oil; a natural resin, such as rosin; a synthetic resin of the tar-acid group or of the urea-formaldehyde type; or other substance. Up to the present time unmodified alkyd resins have not been commercially important.

A wide variety of types is obtained by the use of different materials and different modifiers. The variations begin with the dibasic acid used, and with the polyhydric alcohol used. The modifications possible are practically endless, and almost any fixed oil or the corresponding[27] fatty acid, and most of the natural or synthetic resins may be used. The importance of the modifier is shown by the proportion used in most alkyd resins. On the average, approximately 50 percent of the total weight of the drying and semidrying alkyd resin products is modifier, 30 percent dibasic acid, and 20 percent polyhydric alcohol. The proportions will, of course, vary with individual types. Certain types on the market contain only 25 percent modifier while others have as much as 75 percent.

In a new industry such as this, rapid changes in types and applications must be expected. Extensive research is being carried on by various groups. The raw material makers are seeking cheaper products or those with special properties; the resin makers are investigating an endless number of modifications, and the makers of surface coatings are testing most of the new types offered.

Development and patents.

Probably the earliest record of research leading to the development of the alkyds was that of van Bemmelen, who reported in a German technical journal in 1856 the sirupy products obtained by heating together succinic acid and glycerin or citric acid and glycerin. The first investigation of the phthalic anhydride-glycerin resins was recorded in 1901.[3] Watson Smith, while engaged in research on phthalein dyes, obtained a transparent, highly refractive resinlike substance when glycerin and phthalic anhydride were heated together. Smith recommended the product as a cement for ceramic wares.

During the period 1910-16 the research laboratories of the General Electric Co., engaged in research on a synthetic resin from glycerin and phthalic anhydride. As a result of these studies numerous patents were granted for this type of resin to which the trade name Glyptal was applied. Intensive research was carried on by several firms, many variations were developed, and literally hundreds of patents were granted.

The paint and varnish industry has been undergoing radical readjustment. Methods and natural products, which for decades or centuries had changed very little, are giving way to synthetic creations of our laboratories. The first important departure from the traditional practices was the development of nitrocellulose lacquers. The commercial application of the alkyd resins followed, and their use is increasing rapidly. Because this development is still comparatively young, the large number of modifications offered has confused the coating manufacturer. It is probable that many of the synthetic products now being marketed have no special technical or economic justification and that they will in time lose out in competition with better products known at present, or still to be developed.

United States Patent No. 1,893,873, dated January 10, 1933, granted to R. H. Kienle and assigned to the General Electric Co., was considered one of the basic patents in this field. Early in 1936 it was declared invalid in a suit claiming infringement brought against the Paramet Chemical Co. of Brooklyn, N. Y. The decision in this case seems to have opened the glycerin-phthalic anhydride resins to a large number of manufacturers.

[28]

Among the principal brands of alkyd resins now on the domestic market are Beckosol, Dulux, Esterol, Glyptal, Rezyl, and Teglac. Each of these trade names identifies a series of products.

Classification of alkyd resins.

A number of classifications of the alkyd resins are possible and practical. Since by far the most important applications are in surface coatings, and their use in molding compositions is relatively unimportant, it seems advisable at this time to emphasize the more important use. For the purpose of this survey the following classification is used:

• (1) Drying alkyd resins.
• (a) Unmodified.
• (b) Modified with natural materials.
• (c) Modified with other synthetic resins.
• (d) Modified with other synthetic resins and oil extended.
• (2) Semidrying alkyd resins.
• (3) Nondrying alkyd resins.
• (4) Miscellaneous modified alkyd resins.
• (5) Alkyd resins in water dispersion.
• (6) Alkyd resins in molding compositions.

At least 75 percent of the alkyd resin finishes used at present are of the drying type and about 15 percent of the nondrying type.

Unmodified drying alkyd resins.—This class of alkyd resins consists of a series of compounds made from polyhydric alcohols, polybasic acids, and fatty acids in chemical combination. The alcohol is usually glycerin, and the polybasic acid largely phthalic anhydride or acid, although others, such as maleic anhydride (acid) are increasing rapidly in importance. The fatty acid or oil used may be linseed, tung, perilla, hempseed, soybean, sunflower, safflower, or other drying oil. It is believed that tung oil and perilla oil are the most important at this time.

Unmodified drying alkyd resins are characterized by excellent durability but limited resistance to water in air-dried finishes. Both in air-dried and in baked finishes they are outstanding as to flexibility, quick drying, long luster life, and permanent adhesion. Their principal uses are in finishes for interior walls and woodwork, automobiles, coatings on steel such as for refrigerators, railway equipment, bridges, advertising signs, and lithographed containers. In these applications the products of this type compete with nitrocellulose lacquers and the older types of varnishes and paints. While the initial cost is higher, greater durability is obtained together with faster drying, flexibility, and hardness.

Probably the largest field for surface coatings is outdoor wood finishes. Several attempts have been made to adapt pure alkyd finishes to this use but with limited success because the hard and non-porous finish does not permit the escape of moisture contained in the wood and the pressure developed from vaporization of the moisture by the sun’s rays tends to lift the coating from the wood surface. Recently it has been found practicable to incorporate from 15 to 20 percent alkyd resins in conventional types of outdoor paints for wood. Here the use of alkyds has contributed greater durability and retention of fresh appearance over a longer period. Paints of this type are now on the retail market.

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Drying alkyd resins modified with natural materials.—This type of alkyd resin is modified principally with natural resins, such as rosin, damar, mastic, shellac, or copal. The use of these natural resins imparts hardness to the resin but shortens its durability. They make the product less expensive, permit easier incorporation of the drying oil, and in some instances increase the water resistance.

Their principal application is to modify nitrocellulose lacquers and lacquer sealers, in order to impart gloss, hardness, and easy sanding. It has been said that the commercial production of drying alkyds modified with natural resins was as important a development in the surface coating industry as the discovery of the alkyds themselves.

Drying alkyd resins modified with other synthetic resins.—Drying alkyd resins may be modified with tar-acid formaldehyde resins, tar-acid furfural resins, urea-formaldehyde resins, petroleum resins, and the coumarone and indene resins.

Modification with tar-acid resins gives a quicker setting, harder drying finish with a higher gloss. Alkyd resins so modified are adapted to both air-drying and baked undercoats and finishes; they have good durability and adhesion and good resistance to grease, oils, alcohol and abrasion. For some uses the tar-acid resin modification gives better qualities than either component possesses alone, but in light colored finishes it has a tendency to cause the finish to yellow. Coatings made of drying alkyd resins modified with tar acid resins are widely used on automobile chassis, fenders, and bodies, machinery coatings, steel fixtures and toys; they are especially suitable for primers, undercoats, and finishes on metal.

Modification with urea resins produces baked-finish coatings. As much as 40 percent of the urea resin is incorporated. It makes possible coatings with a full range of permanent colors and improves their hardness and mar-proofness, whereas without the ureas the combination of color range with hardness had been difficult to obtain. The urea resin modified alkyds find use on metal surfaces of articles which must stand rough handling, such as toys, furniture, and motors.

Modification with petroleum resins produces air-dried finishes. For industrial use on metal they give coatings with better adhesion, dispersion of pigments, and resistance to acids, alkalies, and moisture at a lower cost than is obtained by ester gum or tar-acid resin modification. The petroleum resin modification minimizes skinning and improves the luster and the flow.

Drying alkyd resins modified with other synthetic resins and oil extended.—Excellent water resistance and versatility are the characteristics of finishes made of alkyd resins modified with other synthetic resins (usually tar-acid) and oil extended. The incorporation of drying oils gives a low cost finish with better compatibility and brushing and with the combined properties of a quick-setting varnish and an alkyd resin. Although not so durable or quick setting as the unmodified finishes, they have better water resistance. These finishes may be brushed or sprayed, air-dried or baked. They have wide industrial and architectural uses.

Semidrying alkyd resins.—Cottonseed oil is the principal modifier in semidrying alkyd resins. Alkyd resins of this type are used in finishes requiring maximum gloss and color retention. When baked[30] on metal at high temperatures they show no tendency to wrinkle. They are used as reinforcing agents to increase flexibility and durability, and to plasticize other finishes.

Nondrying alkyd resins.—The nondrying or nonoxidizing alkyd resins are those containing a nondrying oil, such as castor oil or coconut oil, or the fatty acid of a nondrying oil, such as stearic, palmitic, or oleic acid. Nondrying oils make the resin less sensitive to heat hardening and impart greater flexibility. These resins are used principally as plasticizers in nitrocellulose lacquers. In this use they have the advantage of better retention of plasticizing efficiency than other plasticizers, many of which are lost by evaporation, migration, absorption, or oxidation. These modified nitrocellulose lacquers, either clear or pigmented, are used for coating wood, composition board, cloth, paper, rubber, leather, and similar surfaces.

Miscellaneous modified alkyd resins.—This group includes alkyd resins modified with materials other than those already discussed. To date (1938) there has been little, if any, commercial production of such resins. There are many modifiers which have been suggested and which might be used but for the fact that they are too expensive. Among these are butyl alcohol and benzoic acid.

Alkyd resins in water dispersion.—Emulsions of alkyd resins in water are now available for use in clear and pigmented coatings. These are sold in the form of paste containing 40 to 50 percent solids and are diluted with water at the time of application. They are especially suitable for coating porous surfaces, such as brick, concrete, plaster, stucco, and masonry of all kinds. They are applied by brushing or spraying and they combine the ease of application of water paints with the durability, washability, and hardness of oil paints. They dry quickly, and the dried film cannot again be dissolved or suspended in water; the coating can therefore be washed or, after several weeks, scrubbed with cleansers. Compared with oil paints, they give better coverage, are easier to apply, and cost appreciably less. Compared with other types of water paints, such as kalsomine, they give a glossier coating of greater durability and superior appearance; they seal porous surfaces better; their covering capacity is greater; and their applied cost is slightly less per square yard of surface.

Coatings of this type may be applied directly over fresh plaster without a sizing coat, since they allow the curing of the plaster to continue. The usual paint pigments may be incorporated.

A special use of the water dispersed alkyds is on asphalt or tar since they are nonbleeding in the solvents of these materials. This quality permits their use for traffic and zone markers on streets.

Alkyd resins in molding compositions and other uses.—The alkyd resins are much less important as binders in molded articles than in coatings and finishes. Conversion of the resin to the insoluble infusible form is extremely slow, requiring days as compared with minutes for the tar-acid and urea resins.

The alkyds are used as binders for flake, powder, and split mica to produce insulation material of high electrical strength. Other uses are in the production of linoleums; gaskets; brake linings; laminated fabric, paper, and cardboard sheets; printing inks; and coated paper, textiles, and leathers.

[31]

Pigments and solvents in alkyd finishes.

Since the alkyd resins are largely used in surface coatings and finishes and since this application in this field is producing great changes in the industry, it is appropriate to consider the effect of their use on other materials.

The average alkyd resin consists of 50 percent glycerol phthalate modified with 50 percent oil, fatty acid, natural resin, or synthetic resin. The alkyd and modifier are dissolved in a solvent, usually a coal-tar light oil such as toluol, or xylol, or a petroleum solvent, and pigmented with titanium dioxide or other pigment. Highly basic pigments such as zinc oxide, carbonate white lead, whiting and aluminum hydrate (all important pigments in the conventional types of finishes) are not used in alkyd finishes.

Production in the United States.

Prior to 1929, the domestic production of resins from phthalic anhydride was confined largely to one maker. The quantities produced were relatively small. In 1929 there were three producers, the volume of whose production exceeded one million pounds for the first time. Beginning with 1933 the Tariff Commission collected and compiled production and sales statistics for these resins. They are shown in table 7.

Table 7.—Alkyd resins from phthalic and maleic anhydride: United States production and sales, 1933-37

In 1933 there were 6 makers of resins from phthalic anhydride, in 1935 there were 15, and in 1937 there were 35. The 1937 output of alkyd resins from phthalic anhydride was 58,450,032 pounds net resin, with sales of 32,583,307 pounds valued at $6,446,011. Producing plants are well scattered through northern and eastern United States. In 1936 fewer than one-third of the makers accounted for about 90 percent of the output.

The domestic production of resins from maleic anhydride was reported for the first time in 1933. The output in that year consisted of experimental quantities produced by two firms. A small increase in production occurred in 1934 when another maker began operation. In 1936 there were eight producers and the output was many times that of 1934. In 1937 there were 12 makers of these resins with an output of 2,803,987 pounds and sales of 2,154,988 pounds, valued at $418,183. It is the opinion of some persons in the industry that in volume of production and sales the resins from maleic anhydride[32] will in the near future approach that obtained from phthalic anhydride.

Imports into and exports from the United States.

No imports of alkyd resins have been recorded in official statistics.

Exports of alkyd resin coatings and finishes are not separately shown, but data collected from the several producers show that appreciable quantities were exported in recent years, principally to Central and South American countries.

One of the most important series of thermosetting resins is the group made by condensing urea and formaldehyde. As early as 1897 it was discovered that an amorphous condensation product was obtained from the reaction of urea and formaldehyde. The clear glass-like mass obtained led to considerable research work toward the development of a substitute for glass. It was found, however, that the resin obtained absorbed moisture, resulting in a dimming of its luster, and that on standing for a time, the condensation continued producing cracks, fissures, and disfigurements in the molded article. In 1926 a successful commercial product was developed in England by the use of thiourea. Cost of production, however, was high. The addition of thiourea gave the product greater strength and water resistance than that obtained with urea alone but retarded the rate of cure. Also the sulphur present attacked steel molds, which necessitated the use of expensive chromium plated or stainless steel molds.

About 1929 the first successful straight urea product was perfected in the United States. It was found that a filler, such as highly refined alpha cellulose, minimized the stresses. The filler (as much as 30 to 40 percent is usually incorporated), destroys the transparency but permits the manufacture of translucent articles in a wide range of color. Many of the colors possible with the urea resins, particularly the light shades, cannot at present be obtained in molded tar-acid resins.

An interesting fact concerning these resins is that they are produced indirectly from four gases: Ammonia, carbon dioxide, hydrogen, and carbon monoxide. Ammonia and carbon dioxide react to form urea, and hydrogen and carbon monoxide yield methyl alcohol which is converted to formaldehyde.

Description and uses.

The urea resins are outstanding largely because of their brilliancy and depth of color, properties not readily obtained in other thermosetting resins. Being odorless and tasteless and completely resistant to oils and greases, they are adapted to use in the manufacture of cosmetic containers. Concentrated acids and alkalies attack the resin. The electrical properties of the urea resins compare favorably with those of the tar-acid resins. They have a lower power factor at high-frequencies than the tar-acid resins, and are replacing, to some extent, established materials in heavy duty electrical equipment where “tracking” causes trouble. Molded articles made from urea resins are resilient but not unbreakable.

Thermostat Case of Molded Urea Resin.

Source: Plaskon Company, Inc., 2112 Sylvan Avenue, Toledo, Ohio.

Scales Case of Molded Urea Resin.

Source: Plaskon Company, Inc., 2112 Sylvan Avenue, Toledo, Ohio.

[33]

The important uses of the urea resins are dictated by their pleasing color and appearance. In 1935 the largest outlets were in buttons and buckles, in bottle closures, and in such premium items as biscuit cutters and cereal bowls distributed by a large food manufacturer. Tableware, bathroom fixtures, all sorts of containers and closures, housings for radios, clocks, scales, and other machines for retail stores, and light-colored wall plates and switches, knobs, handles, and trim on dash panels of automobiles, and handles and trimming on gas and electric ranges were among the widespread applications of the urea resins. In 1938 probably the fastest growing outlet for urea resins is in lighting equipment. Use in packaging, in closures, and in housings, is also increasing. Tableware, the principal outlet for a number of years, is declining markedly.

A comparatively new use is in shades and reflectors, replacing opal glass. The unpigmented resin is highly translucent and gives high light transmission and an exceptional degree of light diffusion. These properties, together with low unit manufacturing costs, reduced shipping costs, and resistance to breakage make the urea resins an ideal material for all sorts of shades and reflectors for direct and indirect lighting fixtures. Many of the shades used in railway cars are of this material. The resin is available in degrees of denseness and opacity to give particular ratios of reflection and transmission. Reflectors as large as 28 inches in diameter are on the market.

Although molded articles are the large outlets for the urea resins, other applications are of increasing importance. Sirups used to impregnate paper and cloth are used in laminating and the resulting materials have unusual decorative possibilities. The surface is hard and durable and the wide range of colors possible permits very attractive applications. The urea resins are used both as the principal binding material for laminated sheets or on the surface laminae of sheets where tar-acid resins are used as the chief binder. The latter practice permits a wide color range in decorative materials without loss of strength or other characteristics of the tar-acid resins. In 1937 there were seven makers, and their production of urea resins for laminating accounted for slightly less than 10 percent of the total of all urea resins.

Another application of urea resins which has grown rapidly in the past 2 years is in combination with alkyd resins in surface coatings. In 1937 there were three makers, and their output of urea resins for coatings amounted to more than 10 percent of the total production of urea. Until recently the use of urea resins in paints and varnishes was discouraged by their insolubility in organic solvents and their instability. On the other hand, their lack of color, their high transparency, their hardness, and their freedom from after-yellowing were desirable characteristics. The development of methods for preparing condensates, which overcome the undesirable properties, has made available resins for this use. They are marketed as water-white viscous solutions in a mixture of organic solvents and are intended for use in baking finishes. They cannot be used alone because the cured resin is extremely hard and brittle and lacks adhesion. When combined with more elastic film-forming materials such as drying or nondrying oil alkyd resins, they produce coatings that are mar-proof, resistant to alcohol, grease, oil, and fruit acids, and[34] available in a full range of colors. Applications are in metal furniture finishes, toys, refrigerators, can, and drum coatings.

The value of urea resins as adhesives has been known for many years and one of the first patents issued for such use was United States Patent No. 1,355,834 granted in 1920. Commercial development and application, however, did not take place until the last 2 years. Several brands of urea adhesives are now on the market. These meet the need for a hot-press adhesive which is applied in liquid form, cures rapidly at moderate temperatures, and is economical. For greater economy, the urea adhesive may be mixed with various proportions of flour (up to 50 percent) without affecting its water resistance. Diluted thus it comes within the cost range of animal and vegetable glues and is more durable. At present, it sells for 18 to 20 cents per pound; mixing it with 50 percent flour gives an adhesive for plywood, costing about 10 cents per pound. In 1937 three producers made urea resins for this use.

Other uses are in the treatment of textiles to obtain crease-proof properties and in the impregnation of wood. United States Patent No. 1,951,994 issued on March 20, 1934, reports the preparation of artificial silk from urea resins.

Production in the United States.

Commercial production of urea resins in the United States was reported for the first time in 1929. Early in that year the American Cyanamid Co. concluded an arrangement with the British Cyanides Co. of England for the American rights to manufacture and sell in the United States a resin made from urea, thiourea, and formaldehyde and marketed as Beetle molding powder. A manufacturing unit was built at Bound Brook, N. J., and in 1930 the output was substantial.

In 1931 another producer, the Toledo Synthetic Products Co., began manufacture of urea resins. Several years prior to that time the Toledo Scale Co. started a search for a material light in weight to replace the heavy porcelain-on-steel used in cases for scales. The search led to the urea resins and to commercial production by their subsidiary. In 1935 the Toledo Synthetic Products Company reached an agreement with the Imperial Chemical Industries of England for the interchange of technical and commercial information and of free patent licenses on urea molding and laminating resins. The name of the domestic firm was later changed to the Plaskon Co.

In 1932 the Unyte Corporation started commercial production of urea resins at Grasselli, N. J. This firm was affiliated with the American I. G. Corporation. Late in 1936 the Plaskon Co. took over the Unyte Corporation.

The output of urea resins increased markedly in 1936 and 1937. Statistics for those years cannot be published without disclosing operations of individual firms. It may be stated, however, that the increase in both years over the previous year was considerably greater than for any earlier period. Most of the production was used in molded articles although appreciable quantities were consumed in laminated articles, in surface coatings, in the impregnation of fabric, and in adhesives.

There were 10 domestic makers of these resins in 1937.

[35]

Domestic production and sales of urea resins are shown in table 8.

Table 8.—Urea resins: United States production and sales, 1933-37

United States imports and exports.

Resins obtained from urea and thiourea, if imported, would probably be classified under paragraph 11 of the Tariff Act of 1930. The present rate of duty under this classification is 4 cents per pound and 30 percent ad valorem.

There has been no importation of these resins. This is due principally to the international licensing arrangements which usually include the allocation of markets.

Exports are not shown separately in official statistics.

A new development of widespread importance in the synthetic resin industry is the commercial production of the polymers of certain derivatives of acrylic acid. The commercial exploitation of the acrylates is another example of the belated realization of the value of substances known for many years. Acrylic acid has been known for about a hundred years, and the polymer of methyl acrylate was first described in 1880. It was not until 1927, however, that a suitable method for their commercial production was developed. The study of the many derivatives of acrylic and methacrylic acids leads to the conclusion that those of greatest practical application in the resin field are the lower esters, such as methyl and ethyl, polymerized separately or together.

Colorless transparency, stability against aging, thermoplasticity, and chemical resistance to many reagents are the general characteristics of the acrylate resins. In consistency they range from soft, sticky, semiliquids to hard, tough, thermoplastic solids. Since these widely varying properties are obtained by control of manufacturing conditions, rather than by the use of plasticizers, the resins retain their initial properties indefinitely. Aging and weathering have no effect as they are stable under exposure to heat, light, and oxidizing agents. The methacrylates are harder and tougher but less elastic than the acrylates.

Properties and uses.

The acrylate resins are marketed in a number of forms, such as solutions in organic solvents, dispersions in water, solid cast sheets, rods and tubes, and molding powders. All of these are distinguishable from many other resins by their colorless transparency, adhesive[36] qualities, great elasticity, and chemical resistance. The brilliant water-white color makes it possible to secure masses having a high degree of light transmission and great optical clarity.

The earliest commercial use of the acrylate resins was in laminated safety glass marketed as Plexigum in the United States and as Luglas and Sigla in Europe. The extensibility and elasticity of the resin film gives the laminated glass a flexible or yielding type of break when subjected to a hard impact. Having excellent adhesion to glass there is no need of an auxiliary cement to bond the resin to the glass, nor is it necessary to seal the edges since the resin has good resistance to moisture. The acrylate resin used for this purpose is in the form of a viscous solution in an organic solvent. A film is applied to each sheet of glass, the solvent removed by drying, and the sheets are pressed together.

The harder acrylic resins are used in the form of solid thermoplastics. Methyl methacrylate is of special interest. As the monomer is a mobile liquid it can be cast-polymerized to a solid of any desired shape in predesigned molds or produced in finely divided form for use as molding powder. The cast resin is marketed in this country as Crystalite, Plexiglas and Lucite, and in England as Diakon.

The solid acrylate resins are clearer than cast phenolic resins, not as brittle as the polystyrene resins, and not as tough as cellulose acetate or nitrocellulose plastics. Their transparency and resistance to aging and weather permit their use in applications not previously considered for synthetic resins. Sheets of this resin may be formed or molded into many useful shapes. The aircraft industry has found them suitable for windshields and cockpit enclosures to effect streamlining and thus greatly reduce wind resistance.

Methyl methacrylate is probably the nearest approach to organic glass thus far developed. Its optical properties make it suitable for spectacle lenses, camera lenses, magnifying glasses, and protective goggles. Spectacle lenses are now being made to prescription by molding. It is estimated that 900 molds will supply the requirements of about 98 percent of the prescriptions. The excellent light transmitting quality of methyl methacrylate permits its use in edge lighting, advertising displays, and instrument dials. It is also used in inspection windows in various types of machinery where curved sections are necessary and where glass might be broken.

A synthetic resin combining the properties mentioned, together with high tensile and impact strength, good dielectric properties, ultraviolet transmission, and resistance to water, oil, acids, and alkalies is an important contribution. The acrylates may be colored or have fillers added to give any desired translucency or opaqueness. They can be sawed, cut, blanked, turned, drilled, ground, polished, and sanded much the same as are nitrocellulose plastics.

Airplane Cockpit Enclosures of Cast Acrylate Resin.

Source: Rohm & Haas Company, 222 W. Washington Square, Philadelphia, Pa.

Spectacle Lenses Molded To Optical Prescription From Acrylate Resin.

Source: Rohm & Haas Company, 222 W. Washington Square, Philadelphia, Pa.

A new and interesting application of the acrylate resins is as molded reflectors in a system of indirect highway lighting. The reflectors are pressed from colorless, transparent methyl methacrylate resin and are 1⅝ inches in diameter. They are assembled in a pressed metal housing to form a double facing marker which is snap-locked to the top of an angle iron post. The posts are so located that the reflectors are accurately aligned 3 feet above the pavement edge. An installation has been made on U. S. Highway No. 16 between Detroit and Lansing, Mich., at a cost of about $340 per mile.[37] The motorist provides his own light from his headlights which strikes the reflectors and is returned as a narrow beam of brilliant illumination. The chief of the United States Bureau of Public Roads states that this is a definite contribution to the safety and utility of the highways at night. The reflector is a group of tiny cube corners, over 300 in each disk. Each cube corner is a complete retrodirective optical system; a light ray entering the front surface is reflected from surface to surface of the cube and after the third reflection is directed back toward the headlight regardless of the entrance angle. If the cubes are made with a high degree of dimensional accuracy, the reflected light has a high candlepower, strong enough to be seen for a mile.

Other uses for these resins are in sound recording records, dentures, telephone and radio transmitter diaphragms, novelties, and lighting fixtures.

The monomer (unpolymerized methyl methacrylate) may be used to impregnate wood, cloth, wallboard, cork, paper, electrical coils, tile, or stone, and then polymerized to form the resin. Paper and cloth so treated have many uses, such as in the electrical and food-packaging industries. Laminated sheets find wide possibilities for use in the aircraft field, and for lamp shades. Wood may be impregnated with as much as 60 percent of the monomer. Solutions of these resins in organic solvents, such as ethylene dichloride, ethyl acetate, and toluol, are used in surface coatings, undercoats on difficult adhesion jobs, to impregnate paper and textiles, and in insulation. These coating solutions are marketed in the United States under the trade name Acryloids and in Europe under the trade names, Borron, Plexigum, and Acronol. They may be brushed, sprayed, dipped, and baked. Baking is recommended to give a higher gloss, better adhesion, and a harder film. The dried film has an elasticity of 1,000 percent at ordinary room temperature and the light transmission of clear films is intermediate between ordinary window glass and quartz.

Acrysol is an adhesive consisting of a dispersion of the resin in water and is recommended for use where adhesion is difficult, as on rubber or rubberized surfaces.

Production in the United States.

Commercial production of acrylate resins in the United States was started in 1931 by Rohm and Haas, Philadelphia, Pa., under United States Patents Nos. 1,388,016 of August 16, 1921, and 1,829,208 of October 27, 1931.

Commercial production of methyl methacrylate resins was started in 1937 by E. I. du Pont de Nemours & Co. This development is under United States Patent No. 1,980,483, issued in 1934. The liquid monomer is produced at Belle, W. Va., and shipped to Arlington, N. J., where it is polymerized by heat to the solid resin.

The output of acrylate resins was hardly more than experimental in 1935 but increased somewhat in 1936 and very appreciably in 1937. Although statistics of production are not publishable, it can be stated that in 1937 the output approached that of other synthetic resins made in commercial quantities. The properties of these resins indicate very large commercial production in the near future. Prices[38] of the several types are still high as compared with other resins but should eventually be somewhat lower than those of cellulose acetate and nitrocellulose plastics and slightly higher than those of cast phenolic resins.

Imports into and exports from the United States.

There have been no recorded imports of acrylate resins. The two domestic producers have agreements, licenses, or affiliations with the principal foreign makers of these products, one in England and one in Germany. Such arrangements would account for the absence of imports, except for sample or experimental lots, and might also limit export markets.

Coumarone and indene are present in appreciable quantities in certain coal-tar fractions, especially in the solvent naphtha fractions distilling between 160° and 190° C. No attempt is made to isolate them from the solvent naphtha. Such a procedure would be difficult and expensive and, since polymerization readily takes place in dilute solutions, it is more economical to use fractions of solvent naphtha rich in these substances. The resins obtained are mixtures of polymerized coumarone and polymerized indene.

The solvent naphtha must be refined by fractional distillation and the polymerization very carefully controlled. The polymerizing agent is usually sulphuric acid although metallic salts, such as aluminum chloride, are sometimes used. The yield and color of the resin are affected by temperature and amount of acid used. Light colored resins are the most desirable. After polymerization the acid or metallic salt is removed, the product washed and neutralized and finally distilled. Several byproducts, such as naphtha, paracoumarone soap, and high boiling oils, are also obtained.

Description and uses.

Coumarone and indene resins are produced and marketed in the United States under the trade names Cumar and Neville. A number of grades are available, including the following:

In addition to these, certain types are produced for special purposes.

The coumarone and indene resins are used to a large extent in varnishes for metal and wood. In this application they may be used to replace all or part of the higher priced natural resins and, to some extent, ester gum. Their application is somewhat limited by their rather short durability and elasticity. They are neutral, nonoxidizing and nonsaponifiable and impart to varnishes greater inertness and adhesion, fair dielectric strength, and shorter drying time than many of the natural resins. They cannot be used in nitrocellulose lacquer since they are not compatible with that plastic.

Another important use of these resins is as an ingredient in mastic floor tile, in the production of which a thermoplastic binder is used.[39] Originally, asphalt was used, but demand for light colored tile necessitated some other binder, the requirements for which were met by the coumarone and indene resins.

The next largest application of these resins is in rubber compounding, their effect being to soften the rubber during milling and to facilitate its handling on rolls. They do not affect the aging qualities of rubber and are used as a softener for reclaimed as well as for new rubber.

Coumarone and indene resins are used, to some extent, in linoleum, for impregnating roofing felt, in electrical and friction tapes, paper and cloth sizing, printing inks, brake linings, adhesives, artificial leather, oil cloth, and shoe polishes. As a substitute for chicle as much as 10 percent may be incorporated in the chewing gum mixture. Their application in molded articles is very limited because of their brittleness and low tensile strength.

Production in the United States.

There are three domestic makers of these resins. Statistics of production and sales cannot be published without disclosing the operations of individual companies. The output, however, has increased appreciably in recent years and this type of synthetic resin is now among the most important produced.

Imports into and exports from the United States.

There have been no recorded imports of coumarone and indene resins in recent years. This is understandable because the duty alone would usually be more than the domestic price.[4]

Official export statistics do not separately record these resins, although quantities are exported to nearby countries, including Canada.

Considerable research work has been done on the synthesis of resins from petroleum. It has long been known that cracked petroleum distillates, when stored for a time, have a tendency to form gums. This tendency is so pronounced that inhibitors are added to arrest such formation. These gums are of little value as resins, but it is possible to obtain good varnish resins by oxidation or controlled polymerization of certain distillates of petroleum cracking. By carefully controlling operations, resins of varied properties are obtained and several of them have become commercially important. The unsaturated compounds, largely olefins and diolefins, present in highly cracked petroleum distillates can be polymerized, with certain catalysts. The resin produced depends upon the types of unsaturated hydrocarbons present and upon the conditions of polymerization.

Properties and uses.

Several types of petroleum resins are on the market, one made from the “polymer slop” obtained in the high temperature, vapor-phase cracking operation, and the other prepared primarily for the [40]production of resin. The former is marketed under the trade name Petropol and the latter as Santoresin.

The “Petropol” resins are marketed in two grades, No. 1158 and No. 2138. The specifications for these are as follows:

Petropol No. 1158 is used by core oil makers to replace such vegetable oils as linseed, tung, and perilla. It is used also as a binder and waterproofing agent on rock wool insulation, replacing rosin and mineral oil. For spraying coal to minimize dusting, it has the advantage over calcium chloride of increasing the B. t. u. content of the fuel.

Petropol No. 2138 is a surface coating material which dries by polymerization. A low cost paint is obtained by combining a pigment and a plasticizer with the resin. Such paint dries in about one-fourth the time of linseed oil paints, adheres better to metal, and has greater resistance to water, acids, and alkalies. In varnishes and enamels it replaces 12 to 15 percent of tar-acid resin, minimizes skinning, and gives a higher luster and better flow. Another use of this Petropol is as a binder in brake linings, replacing certain tar-acid resins.

These two Petropol resins are among the lowest priced synthetics, selling at present (1938), in tank carlots, for 2 to 5 cents per pound.

The Santoresins are clear, hard, neutral products, melting at 100° C. They are soluble in drying oils, accelerate the gelatination of tung oil, are nonreactive with pigments, do not yellow on outdoor exposure, and are resistant to alkalies, acids, alcohol, and water. Applications are in protective coatings for wood, metal, paper, leather, cement, plaster, and other materials, in printing inks, plastic tile, linoleum, and fiber packages. Being odorless and tasteless they may be used to line food containers. Their high resiliency and purity recommend their use as a base for chewing gum. Other uses are as an agent for wetting and dispersing pigments in rubber and in surface coatings, to replace ester gum or modified tar-acid resins.

At present the Santoresins are offered at 15 cents per pound in lots of 20,000 pounds or more. Their approximate specifications are:

[41]

Production.

In the United States two makers of petroleum resins are producing in commercial quantities and several others are carrying on extensive research. Production was small in 1935, but increased in 1936 and in 1937. The development and expansion of these resins over the past 2 years indicate that they will become important.

Imports into and exports from the United States.

There has been no importation of petroleum resins into the United States. Exports have been confined to samples and experimental quantities.

The polystyrene resins are thermoplastic products discovered about 100 years ago and are therefore the oldest synthetic resins known. Their practical application has been greatly retarded by the lack of inexpensive raw materials of high purity and by the difficulties experienced in their manufacture.

Ethylene, from petroleum or natural gas, is combined with benzene, from byproduct coke-oven operations, to form ethyl benzene, which is cracked to vinyl benzene or styrene. This monomer is polymerized by heat at 100°-150° C. The resin may be extremely tough or very brittle, depending on the conditions of polymerization. Products having different properties are obtained by (a) low temperature polymerization, (b) high temperature polymerization, and (c) catalytic polymerization.

The low-temperature polymers, sometimes designated as alpha-metastyrol, are produced by polymerizations of vinyl benzene at temperatures under 175° C. A transparent resin, colorless to light yellow, is produced which is remarkably tough, has excellent tensile strength, unusually good dielectric properties, and is resistant to most chemicals.

Polymerization at high temperatures (above 175° C.) yields a brittle resin designated as beta-metastyrol. This type is transparent but usually dark in color, has low tensile strength and shock resistance.

When vinyl benzene is polymerized in the presence of catalysts, the resulting resin is similar to resins obtained at high temperatures, except that it is lighter in color. It is sometimes designated as gamma-metastyrol. Oxidizing agents are usually the catalysts. Clear, colorless, vitreous resins are obtained by excluding air during polymerization.

Properties and uses.

Polystyrene resin is a clear, colorless, highly thermoplastic molding material with high insulating property, moisture resistance, inertness, dimensional stability, and impact strength. It can be molded directly by heat and pressure, and the molded articles are remarkably resistant to discoloration by light. Polystyrene has a dielectric constant of 2.6, a power factor of 0.02 percent, and is equivalent to fused quartz as an electrical insulator of low dielectric loss. Films of 0.002 inch thickness have a dielectric strength of more than 2,000 volts per mil thickness, which is better than that of any other available synthetic resin and even better than that of shellac. The tensile strength of the resin is 5,500 to 7,000 pounds per square inch, and its impact[42] resistance remains unchanged at temperatures as low as minus 70° C. It transmits all wave lengths of light down to 3,000 Angstrom units.

Polystyrene is adapted to large scale production of transparent, translucent, and opaque moldings in a wide variety of colors. It is easily molded by injection processes, softening at about 150° F. and is molded at 300° to 375° F., under 3,000 to 30,000 pounds pressure per square inch. As much as 40 percent filler may be used without seriously affecting the tensile strength, although the filler does affect the dielectric properties. Since the resin is thermoplastic there is no waste in the molding operation; scrap material may be reground and used again.

The unusual properties of these polystyrene resins should give them widespread applications when the cost is low enough to make them competitive with other materials. Potentially large volume outlets are in radio frequency insulation; in dentures because of the strength, low specific gravity, ease of coloring, and absence of odor and taste of the material; in electrical parts for submarine and aircraft storage battery cases and separators; and for the manufacture of glass eyes.

Other possible applications of polystyrene resins are in metal lacquers and in light colored enamels. Their toughness and light color, together with their solubility in cheap solvents, suggest their use for these purposes. Such lacquers are said to be quick-drying, resistant to water, and moderately so to acids and alkalies.

Production in the United States.

For a number of years, the Naugatuck Chemical Division of the United States Rubber Co. produced small quantities of polystyrene resins, which were marketed under the trade name Victron when for general purposes and under the trade name Marvelyn when for use in dentures. Little progress was made because of high costs and failure to produce a water-white product. The sales price was between $1.50 and $2 per pound. Early in 1937 the Naugatuck Chemical Division transferred its patents on polystyrene resins to the Carbide and Carbon Chemicals Corporation.

The Dow Chemical Co., Midland, Mich., late in 1937 announced commercial production of clear, colorless polystyrene in several forms. Styron is the trade name for the resin from this source. In January 1938, the Bakelite Corporation announced Bakelite Polystyrene. The plants manufacturing polystyrene have a capacity in excess of 2,000,000 pounds a year, and the resin is currently offered at 72 cents per pound.

At least one other domestic firm is doing research on the polystyrenes and expects to produce commercially in the near future.

Imports into and exports from the United States.

At least two commercial types of polystyrene resins are produced abroad. Both are made in Germany and marketed under the trade names Resoglas and Trolitul. Resoglas is a water-white, transparent thermoplastic resin softening at about 150° C. Its water absorption is low, it is nonoxidizing, and does not discolor on weathering and baking. Appreciable quantities are produced in Germany and the sales price there was reported to have been 40 cents per pound during 1936.

Molded Polystyrene Resins.

Source: Bakelite Corporation, 247 Park Avenue, New York, N. Y.

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Small quantities of Resoglas and Trolitul have been imported from Germany in recent years. Table 9 shows the quantities imported in recent years.

Table 9.—Resoglas and Trolitul: United States imports for consumption, 1933-37

With the more advanced development of polystyrol resins in Germany prior to 1938, evidenced by larger commercial production, by wider application, by the marketing of a water-white product at a considerably lower price, it might be expected that imports into the United States would have been in considerably larger amount than shown in table 9. That they were small was probably due to the high rate of duty which made them expensive as compared with other synthetic resins in the United States and thus limited their market to uses in which the others were less satisfactory. Resoglas was reported to have been selling for 40 cents per pound in Germany. The imported resin is assessed for duty under the provisions of paragraph 28 of the Tariff Act of 1930 at 45 percent ad valorem based on American selling price (as a competitive product) and 7 cents per pound. The American selling price of the resin made in the United States until late in 1937, as determined by the Bureau of Customs, Treasury Department, was $1.85 per pound. The duty was therefore 90 cents per pound. Imports of Trolitul were valued at 75 cents per pound, giving a cost of $1.75 per pound laid down, duty paid, in domestic markets. With the present American selling price of 72 cents per pound, the duty would be approximately 36 cents per pound.

Vinyl acetate, vinyl chloride, and to a lesser extent vinyl chloroacetate, are the raw materials (monomers) for the several vinyl resins commercially produced in the United States, Canada, and Germany. These are all esters of the hypothetical vinyl alcohol and are made by the action of acetic and hydrochloric acids on acetylene.

The spontaneous polymerization of vinyl derivatives has been known for many years, although its significance and industrial application have been realized only recently. Vinyl acetate, probably the most important of the vinyl esters, was discovered in 1912 and first made in Canada in 1917.

Vinyl resins may be classified into (a) polyvinyl acetate, (b) copolymers of vinyl acetate and vinyl chloride, (c) polyvinyl chloride, and (d) polyvinyl chloroacetate.

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Description and uses.

Polyvinyl acetate resins.—The several commercial types of vinyl acetate resins are marketed under the trade names Vinyloid A, Alvar, Gelva, Formvar, and Mowilith. The first of these is a product of Carbide and Carbon Chemicals Co., New York, the next three are products of Shawinigan Chemicals Limited, Shawinigan Falls, Canada, and the last is made by the Interessen Gemeinschaft Industrie A. G., Germany. Vinyloid A and Gelva represent the simplest series of vinyl acetate resins and are made by polymerizing the monomer. The softening point and viscosity of the polyvinyl acetate resins increase with higher polymerization. Such resins are colorless, tasteless, odorless, thermoplastic products. They are soluble in coal-tar solvents and are compatible with certain alkyd resins, tar-acid resins, and natural resins. Films of polyvinyl acetate resin are not discolored by exposure, and after irradiation they become opaque to ultraviolet light, are hard and tough, and have good adherence and endurance. Their dielectric strength is good and they do not show a carbon track after the passage of an electric arc. Various grades having softening points from 80° to 200° C. are available.

Polyvinyl acetate resins are used in making transparent papers, paper to metal laminations, glassine papers for food packaging, as a substitute for chicle in chewing gum, and as a component of paints, varnishes, and lacquers. They have the desirable properties of compatibility, durability, resistance to abrasion, and rust inhibition in the surface-coating use. Having the same refractive index as pyrex glass, they leave no line of demarcation when used as a cement for that material. They have been used to stiffen toe-caps in shoes and articles made from paper pulp suspensions. Gelvas are not molded as such because of their tendency to cold flow. They are used, however, as a binder for ground mineral fillers in advertising signs and for wood flour in molded artificial wood carvings. In nitrocellulose lacquers they improve the adhesion, luster, and toughness.

Alvars are made by replacing part or all of the acetate groups in Gelva with acetaldehyde. Their viscosity varies with the degree of polymerization and their properties vary according to the extent of replacement of the acetate groups. The Alvar types do not cold flow when molded, are tougher, harder, and have better adhesion but are less resistant to weathering than the Gelva types. Other properties are about the same as those of the Gelvas. Alvars having 70 to 80 percent acetate group replacement are used chiefly in spirit type varnishes, lacquers, and enamels that must stand exposure to weather. Another Alvar type is used in injection and press molding. The high binding power of the resin permits the use of large percentages of filler without loss of desirable properties. Such moldings may be machined and polished, and take inserts, such as the wood core in shoe heels. Flexible phonograph and transcription records made from the Alvars have gained wide approval. An 85 percent (acetate replacement) type has better impact strength and is used in toilet articles. Sheets, rods, and tubes of this resin may be machined in much the same way as nitrocellulose plastic and used where noninflammability is an asset.

Formvars are made by replacing part or all of the acetate groups in Gelva with formaldehyde. These resins are colorless, odorless,[45] tasteless, and thermoplastic. They have higher softening points and greater tensile and impact strength than the Alvars. They are resistant to alcohols, coal-tar solvents, fats, oils, or water. Moisture transmission rate through a film of this resin is about one-tenth that through regenerated cellulose and one-fourth that through cellulose acetate.

The grades of the Formvars available are designated by the extent of replacement of the acetate group. The 75-percent replacement type has excellent mechanical strength and flexibility and is unaffected by sunlight. Formvars of 95 percent acetate displacement have a tensile strength as high as 10,000 pounds per square inch and offer possibilities in the manufacture of artificial silk and photographic film.

The vinyl resins have made possible a new type of safety glass superior to any heretofore marketed. By condensing butylaldehyde with vinyl acetate, a polymer is obtained which is used as the inner layer between two sheets of glass. Heat and pressure secure complete adhesion and yield a sheet with greater resistance to breakage at low temperatures than the types now in general use.

Although safety glass was invented in 1905, and many substitutes for the original nitrocellulose inner layer have been proposed, only two reached commercial importance before the development of the vinyl resins. These are cellulose acetate and the acrylate resins. Safety glass used in automobile windshields up to about 1930 discolored after a year or two of service. This discoloration was due to the action of the actinic rays of the sun on the nitrocellulose layer. Since 1930 this difficulty has been largely overcome by using an actinic ray filter glass (a special glass with a high iron content) in front of the nitrocellulose sheet, or by using cellulose acetate, which is not discolored to the same extent by light, as a substitute for nitrocellulose. Both cellulose nitrate and cellulose acetate, however, have a tendency to lose toughness and strength at low temperatures, to absorb moisture, and to separate from the glass around the edge unless sealed, and to lose their plasticizer and shrink.

Although a vast improvement over ordinary plate glass, laminated glass made with cellulose nitrate or acetate has the serious defect of being brittle at low temperatures, such as prevail in the winters of northern States. It is easily shattered at zero Fahrenheit, while at 60° F. and above it is quite strong. This shortcoming led to the development of the vinyl resin sheet for safety glass with a remarkable degree of toughness. At normal temperatures it has rubberlike toughness which, although decreased at low temperatures, is not punctured by the impact of a half-pound steel ball falling from a 30-foot height at minus 10° F., whereas nitrocellulose or acetate laminated glass withstands the impact of a fall from not greater than one-tenth this height. A further advantage of the vinyl sheet is that it is water resistant, making the sealing of the edges of the glass unnecessary and thus reducing costs. Exposure to ultraviolet light in Florida sunlight for more than 2 years did not discolor it.

The many desirable properties of the vinyl resins, as outlined above, indicate their widespread use in laminated safety glass when it is available in sufficient quantities. It is estimated that our annual output of safety glass interlayer sheets exceeds 17,000,000 pounds,[46] of which 25 to 30 percent are for windshields, and 70 to 75 percent for side and back windows of automobiles.

At least one of the series of Mowiliths made in Germany is polymerized vinyl acetate. It is recommended as an ingredient of water-white lacquers. It is compatible with nitrocellulose and is extremely durable and not disintegrated or discolored on exposure to weather.

Copolymers of vinyl acetate and vinyl chloride.—The simultaneous polymerization of mixtures of vinyl acetate and vinyl chloride yields resins with the desirable properties of the two reactants. The extent of plasticity is largely controlled by varying the ratio of the vinyl derivatives. Resins high in vinyl chloride content are better suited to molding, and those high in vinyl acetate are better lacquer ingredients. These resins are marketed as Vinylites by the Carbide and Carbon Chemicals Co., New York. They are thermoplastic, odorless, tasteless, and practically nonflammable. Their outstanding properties are resistance to water, soap, acids, alkalies, and alcohol, and their strength and good dielectric properties. Their stability to light is improved by the addition of ultraviolet absorbing compounds and their stability to heat by the addition of lead oleate, calcium stearate, or other bases. Water absorption and compatibility with other resins is increased as the chloride content increases.

The principal types of copolymers are:

Vinylite VYN, high molecular weight. This resin is used in dentures where good fatigue resistance, impact strength, and tensile strength are required. It contains 85 to 88 percent vinyl chloride.

Vinylite VYN, medium molecular weight. This resin is used in general molding and extending applications including sheets, rods, and tubes. Its vinyl chloride content averages 85 to 88 percent.

Vinylite VYN, low molecular weight. This resin is used in moldings, coated paper, lacquers, floor tile, phonograph records, and felt impregnation. It contains 85 to 88 percent vinyl chloride.

Vinylite VYC. This resin of low molecular weight is compatible with nitrocellulose and is used in lacquers and finishes for industrial applications. Lacquers from the Vinylites are called Vinyloids.

The Vinylites for molding are thermoplastic and shrink very little, making them applicable to large moldings. They may be used in extension processes such as tooth-brush preforms, pipe lining, and wall trim. Fillers and pigments may be added, although pigments containing iron and zinc have harmful effects on the stability of the resin. The fillers used are wood flour, mica, talc, and alpha cellulose. Fillers reduce the mechanical strength of the resin and lessen its resistance to water. Plasticizers, such as dibutyl phthalate or tricresyl phosphate, give a softer, more flexible resin. Resins from the copolymers resemble the cellulose derivatives in their molding characteristics, mechanical strength, and appearance.

In lacquers the Vinylites offer high resistance to water, oils, and chemicals. The drying of such lacquers is by evaporation rather than by oxidation. They are suitable for lining food containers, coating concrete, coating paper for bottle cap liners, and as a stiffener for box toes of shoes. Their most successful application at present is as an inside coating for beer cans. Floor tile containing these resins mixed with slate flour or other filler has good possibilities.

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Polyvinyl chloride resins.—Vinyl chloride may be polymerized to give nonflammable resins of varying solubilities. The completely polymerized resin is practically insoluble at ordinary temperatures and is used as a rubber substitute. It is marketed as Koroseal by B. F. Goodrich Rubber Co., Akron, O. Compared with natural rubber, it has greater resistance to acids, alkalies, oils, and alcohol, more flexing life, better resistance to sunlight, water, and oxidation. Solutions of this resin marketed as Korolac are used in special types of varnishes.

Polyvinyl chloroacetate resins.—These resins known as Mowiliths are made in Germany. Application is largely for surface coating. Practically no information on this type is available.

Divinyl acetylene and synthetic rubber.—Two products closely related to those described above but probably not synthetic resins as defined for this discussion are divinyl acetylene, a synthetic drying oil, and Neoprene, a synthetic rubber.

Acetylene, when passed into a solution of copper chloride and ammonium chloride, combines with itself. When two molecules of acetylene react monovinyl acetylene is formed, and when three molecules of acetylene react divinyl acetylene is formed. Monovinyl acetylene reacts with hydrochloric acid to give chloroprene, which is polymerized to synthetic rubber or Neoprene.

Divinyl acetylene is a colorless liquid which darkens on exposure to light and which has an onionlike odor. When polymerized liquids are formed, then as the reaction progresses viscous products and finally insoluble, infusible, inert resins. By arresting the reaction before the gel point is reached, an amber colored heavy liquid, soluble in aromatic hydrocarbons, is obtained. Since divinyl acetylene will continue to polymerize at ordinary temperatures, this property is taken advantage of in using it as a basis for paints, under the name “synthetic drying oil.” Clear, amber films are obtained from solutions of this oil in solvent naphtha. Divinyl acetylene is quick drying, is many times more impervious to moisture than linseed oil, and is thermosetting. It is not attacked by solvents but is attacked by strong oxidizing agents, and the gelled material may ignite spontaneously.

Although not classified as a resin, synthetic rubber is discussed here because of its close chemical relationship to the vinyl resins. It is made commercially by E. I. du Pont de Nemours & Co., Wilmington, Del., and is marketed as Neoprene. It is sold as a plastic polymer which is vulcanized and processed much the same as natural rubber except that sulphur is not essential to vulcanization. Synthetic rubber is higher in price than natural rubber, but it has certain properties which make it suitable for service conditions where natural rubber is unsatisfactory. Among these properties are its resistance to gasoline, oils, and greases, and to elevated temperatures. It does not check or crack on exposure to sunlight, nor does it oxidize as rapidly as natural rubber. Its principal applications are in special gaskets, printing rolls, jackets for high tension cable, linings for gasoline or oil hose lines, balloon fabrics, diaphragms for regulators, and packing for compressors. Its existence acts as a limit to the increase in the price of natural rubber and assures a supply in emergencies.

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Production in the United States.

Some of the products described are commercially produced in the United States; others in Canada or in Germany. Those made in the United States are usually not made by more than one firm, so that statistics of production and sales are not publishable. The vinyl acetate resins have been produced principally in Canada; the copolymers of vinyl chloride and vinyl acetate are domestic products. In 1935 the United States output of all vinyl resins exceeded 1,000,000 pounds, a figure that was increased in 1936 and 1937.

The Canadian output of Gelva and Alvar has reached commercial quantities; that of Formvar is still confined to experimental plant lots.

The acceptance of vinyl resin sheets for safety glass will greatly increase the output in 1938. The basic patent, known as the Morrison-Blaike patent, United States No. 2,036,092 issued on March 31, 1936, is owned by Shawinigan Chemicals, Ltd., Montreal, Canada, who have licensed several domestic producers. The monomer (vinyl acetate) is now produced at Niagara Falls, N. Y., by the Niacet Chemicals Corp., which is jointly owned by this Canadian firm, Carbide and Carbon Chemicals Corporation, and E. I. du Pont de Nemours & Co. It is also produced by du Pont at Belle, W. Va. It is shipped, in tank cars, to polymerization and sheet-forming plants at Indian Orchard, Mass., Arlington, N. J., and Charleston, W. Va. The Indian Orchard plant, known as the Shawinigan Resin Products Co., and jointly owned by the Canadian firm and the Fiberloid Corporation, is now in operation. The plant of the du Pont Company at Arlington, N. J., began production in May 1938, and that of Carbide and Carbon Chemicals Corp, at Charleston, W. Va., is in production. These plants have a combined annual capacity of about 10 million pounds of vinyl resin sheets. According to present plans this new safety glass will be available for 1939 model automobiles. The resin sheet to be used is 0.0015 inch thick as compared with the 0.0025 inch thickness of the present cellulose acetate and nitrocellulose sheet. Several trade names have been adopted for the vinyl resin sheets, among which are Vinylite X, and Butvar. The licenses granted to domestic makers under the Morrison-Blaike patent also permit them to make vinyl acetate resins for purposes other than safety-glass sheets. Considerable progress has been made in adapting these resins to injection molding operations for the production of tooth-brush handles, combs, closures, and other parts.

Imports into the United States.

The official statistics of imports of vinyl resins prior to 1936 are not satisfactory for purposes of comparison. Imports could be entered under either paragraph 2 or paragraph 11 and could be included either with the statistics of imports of vinyl acetate (see table 91, page 141) or be thrown into a general group of non-coal-tar synthetic gums and resins, n. s. p. f., which in addition to vinyl resins would include the acrylates and ureas. Table 10 gives imports of synthetic resins under paragraph 11 of the Tariff Act of 1930.

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Table 10.—Synthetic resins classified under paragraph 11:¹ United States imports for consumption 1931-37

A better idea of the imports of vinyl resins prior to 1936 is obtained by an invoice analysis of imports through the Port of New York under paragraphs 2 and 11. Table 11 shows imports of vinyl acetate resins based on such an analysis for 1934 and 1935 and on official statistics for the years 1936 and 1937.

Similarly table 12 shows imports of Mowilith resins based upon import analysis for the period 1932-1935, and upon official statistics for 1936 and 1937.

Table 11.—Vinyl acetate resins: United States imports for consumption, 1934-37

Table 12.—Mowilith resins: United States imports for consumption, 1932-37

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Prior to January 1, 1936, the rate of duty on imports of vinyl resins was 6 cents per pound and 30 percent ad valorem under paragraph 2, and 4 cents per pound and 30 percent ad valorem under paragraph 11 of the Tariff Act of 1930. Under the terms of the trade agreement with Canada, the duty under both paragraphs was reduced to 3 cents per pound and 15 percent ad valorem. This rate was generalized to the other countries from which we have received imports, with the exception of Germany.

Exports from the United States.

Exports of vinyl resins are not separately shown in official statistics.

The synthetic resins already discussed are those in substantial commercial production but, by no means, the only ones known or produced. Several thousand new ones have been reported and the search continues in laboratories throughout the world. A successful new product must be one made from inexpensive raw materials or must possess some property or advantage that will permit its sale at a price level above that of other resins.

No attempt is here made to list the host of less important resins. Certain ones of unusual interest or possessing unique properties are described below. These include resins obtained from adipic acid, aniline, citric acid, diphenyl, furfural, lignin, sugar, and sulphonamide.

Adipic acid resins.

The resins from adipic acid are classed as alkyd resins. Those obtained by the condensation of adipic acid and glycerin are soft and rubbery and are used to some extent in surface coatings and in photographic films. In these the resin is formed in three stages as in other alkyd types: A soluble liquid, a viscous rubbery product, and a form insoluble in the usual solvents.

Commercial domestic production of these resins was reported for the first time in 1935 and the output has increased each year since then.

Aniline resins.

Resins obtained by condensing aniline and formaldehyde have been developed in recent years. Much of the research on this type of resin was done in Switzerland by the Ciba Co., which holds a number of patents on it. The Swiss product, called Cibanite, has excellent electrical and mechanical properties. At least one domestic manufacturer is licensed under the Swiss-owned patents.

Citric acid resins.

Considerable interest has recently been manifest in synthetic resins derived from citric acid. The sharp decline in the price of citric acid, as a result of large scale synthesis from sugar has placed it within the realm of possibility as a raw material for synthetic resins.

The citric acid resins, classed as alkyd resins, are obtained by condensing citric acid and glycerin. Commercial production is said to have started in Europe, but there is no known domestic production as yet.

[51]

Diphenyl resins.

A series of products known as Aroclors and made by chlorinating diphenyl are available in commercial quantities.

Diphenyl was commercially produced for the first time by Swann Research, Inc., at Anniston, Ala., about 1928. The demand for it as a heat-transfer medium resulted in large scale output. Later it was found that certain of the chlorinated compounds of diphenyl possess valuable resin properties.

The Aroclors range from a clear mobile oily liquid to an amber colored transparent solid. They are thermoplastic, do not polymerize or oxidize, and are therefore nondrying. They may be dissolved in varnish oils, such as tung oil and linseed oil, to give varnishes which are resistant to alkali and water. The diphenyl resins are good adhesives on metal and glass and give strong joints between such surfaces. They have a high dielectric constant, resistivity, and a low power factor. Their chief use is in wire insulation.

The domestic production of chlorinated diphenyls is, at present, solely by the Monsanto Chemical Company, St. Louis, Mo.

Furfural resins.

Large scale commercial production of furfural, an aldehyde obtained from oat hulls and other farm waste, has made it available for synthetic resin manufacture.

Tar-acid furfural resins possess certain outstanding properties, such as great dimensional accuracy, great reaction speed to the infusible solid stage, and unusual strength and toughness. They are available in dark shades only. Printing plates as large as those of metropolitan daily papers are molded from them as are radio tube bases, all sorts of electrical parts, and machined parts requiring great dimensional accuracy. Other uses are in abrasive wheels, varnishes, and adhesives.

Probably the largest domestic maker of furfural resins is the Durite Plastics Division of Stokes and Smith Company, Philadelphia, Pa.

Resins from sugar.

Many attempts have been made to utilize sugar as a raw material for synthetic resins. United States Patent No. 1,949,831, dated March 6, 1934, claims a process for the manufacture of molding compounds by condensing saccharide with aldehydes and urea. Pure sucrose yields a clear, colorless, nonresilient resin, while molasses and cane sugar give dark-colored resins. The trade name Sakaloid is used to designate certain of these resins; there is, however, no known domestic production. Sucrolite is the trade name of a brand of resins from sugar produced in Europe.

Sulphonamide resins.

The sulphonamide resins were developed from para toluenesulphonamide, a byproduct obtained in the manufacture of saccharin (synthetic sweetening agent).

Para toluenesulphonamide, condensed with formaldehyde or other aldehyde, forms a viscous mass which, on heating, is converted to a hard colorless resin. Such resins are compatible with cellulose acetate or nitrocellulose in lacquers, the combination yielding clear, colorless lacquers of good gloss and adhesion. Other possible uses are as an adhesive in safety glass, in certain molding compositions, in insulating materials, and to deluster artificial silk.

[52]

Domestic production of sulphonamide resin is entirely by the Monsanto Chemical Co., St. Louis, Mo. It is marketed under the trade name Santolite.

The discussion of the various synthetic resins on pages 11 to 52 carries in each case, under the heading of production, a notation of the number of companies producing that particular resin; and the discussion on pages 86 to 141 of important raw materials for these resins describes briefly the conditions under which these materials are produced. We shall now consider the interrelationships between industries producing the several resins, and the relation of the resin industries to their raw materials and to some of the important resin-consuming industries.

No description of the organization of a rapidly expanding industry can be expected to remain accurate for long. But regardless of future changes that may be expected, the general pattern seems definite enough to make possible a few broad generalizations. At present the producers of synthetic resins may be classified in two groups: those making alkyd and tar-acid resins, and those making all other synthetic resins.

The alkyd resins and the tar-acid resins are produced in large volume, and for these resins the patent situation is such that there is nothing to exclude new producers. The result has been that new firms have entered the field and there has been a marked tendency for concerns using these resins on a large scale to produce them. This general situation may be expected to continue as long as the volume of consumption of these resins is rising. But when consumption levels off, it would not be surprising if increased competition for new business resulted in consolidations of some of the producing units.

Each of the other synthetic resins is produced by a small number of firms and this may be expected to continue as long as the production of a particular resin is small, or basic patents dominate the situation. When and if the situation in these respects changes for some of the other resins, they will probably develop the same tendencies as now exist in the production of the tar-acid and alkyd resins.

Horizontal relationships between resin producers.

Horizontal relationships between companies are those between different units in the same industry (say two tar-acid resin producers), or in different industries each operating at the same stage of industrial production (say a tar-acid resin producer and a producer of urea resin). As a rule, extensive horizontal relationships are not common in relatively young industries, and this is true of the production of synthetic resins. In general, it has not been necessary to absorb competitors to achieve a greater volume of sales, and efforts have been directed to exploiting the possibilities of expansion in a growing market. This necessitated solving technical problems concerning improvement of the product and its production on an ever larger scale; legal problems regarding patents (protection of those owned, and the policy to be adopted toward unadjudicated patents owned by others); and the marketing problem of convincing prospective[53] customers of the worth of a new product. These and other problems incidental to successful competitive production and sale of a given type of synthetic resin have been sufficient to restrain the desire to produce more than one type.

The patent situation of most synthetic resins is extremely complicated. In the case of tar-acid molding resins the basic Baekeland patents have expired, but for other synthetic resins either the basic patent is still in force, or it is difficult to say which is the basic patent, because of lack of adjudication by the courts. In all cases dozens of supplementary patents are in force and sometimes hundreds. As a result the patent situation, though one of the bars against entering into a new field, frequently forces some relationship between producing units in the same synthetic resin field. Cast phenolic resins afford an example of patent-licensing of several corporations by another with the payment of royalties as compensation. In a number of other branches of the resin industry, such as the laminated tar-acid resins and the alkyd resins, the mutual desire of producers to avoid litigation has apparently resulted in “gentlemen’s agreements” not to sue.

Vertical relationships of resin producers.

A vertical relationship is one between producers operating at different stages of industrial production, such as a firm producing resin and a firm producing a resin raw material or between the former and a firm that is a resin consumer. The incentive for a consuming industry operating on a large scale to make its own resins is naturally greater than for one using only small quantities. Therefore we may expect to find instances where a process consuming the resin in quantity and resin manufacture are both performed by the same company provided other conditions (such as the patent situation and knowledge of the art of manufacture) are favorable.

Tar-acid resins for molding.—The present practice of molding resins is favorable to large-scale production. The shaping of the mold is expensive, involving skilled labor upon hardened steel; but once the mold is made it may be used to produce tens or hundreds of thousands of units. Subsequent labor upon the molded product is usually limited to the simple task of smoothing the line where the flash is broken off, since the product comes from the mold in the color and with the surface and shape desired.

The usual arrangement at the present time is to have a battery of presses, grouped around central units which supply hydraulic pressure and steam for heat. A measured amount of molding powder or a pellet of compressed molding powder is applied to each cavity by the press operator, who controls by hand the time of application of heat and pressure and removes the article from the press. The cycle is a matter of minutes, and since each cycle produces a finished article if the molding is large, or a number of them if it is small, daily production per worker is high. The estimated average costs of the different elements in the process have been apportioned as follows: the cost of raw material is about one-third the cost of the finished product; and the combined cost of the mold allocated per unit, the labor cost per unit, and overhead the remaining two thirds.[5] On [54]small runs labor cost and particularly allocated mold cost would be much higher, so that molding is usually uneconomic where only small quantities of the finished product are desired.

In 1937 there were eight molders that produced their own tar-acid resins in whole or in part. One of these molders was the third largest producer of such resins. In the same year six producers of tar-acid resins for molding, including the first, second, fourth, and fifth largest, confined their activities to resin making. One producer of raw materials for tar-acid resins also made the resin on a moderate scale.

This picture of interstage relationship as it existed in 1937 may be somewhat modified by new developments in molding presses. There are now available self-contained presses which are not dependent upon other units for their supplies of heat and pressure and which are either semiautomatic or automatic. The semiautomatic press requires an operator for charging the cavity and removing the molded product, but once adjusted automatically applies the heat and pressure and controls the time of the pressing cycle. The automatic press, adapted as yet only to the simpler moldings, requires no attention whatever. These presses are more expensive, but may be set up anywhere and require less skilled labor. There is the possibility that they may be installed by some industrial users of molded articles, and thus take some business from the custom molder. If this occurs, such molders will presumably buy their resin from companies that are primarily resin makers, since their requirements of the material would not ordinarily be large enough to justify making their own.

Tar-acid resins for laminating.—The manufacture of laminated resin products is most economic when done on a large scale, in which case the impregnation of the paper or fabric becomes a continuous process, the material feeding from a roll through resin sirup and then through drying towers, where time and heat may be controlled. The impregnated material contains resin in the B-stage. The material is then cut up and the sheets piled together (the number depending on the thickness desired) and sent to huge presses which, with heat and pressure, compact and unite the layers and convert the resin to the C-stage. If it is desired to produce decorative panels with a smooth surface, the top sheet used is one colored or printed with a design (perhaps a photographic reproduction of the surface of a cabinet wood) and placed between polished chromium-plated metal sheets before going to the press. Rods and coil forms as well as flat sheets are commonly made from laminated material. Any of these forms may undergo subsequent fabrication; rods and coil forms cut to required length, thin sheets stamped to shape, gear blanks cut to final form on automatic gear machines, and decorative panels sawed to shape.

Many laminators purchase all their resin requirements, but a number of them make part or all of the tar-acid resin they use. In 1937 there were seven laminators who made tar-acid resins (including the second, third, and fourth largest producers of such resins) and four producers of tar-acid resins for this use (including the largest) which did no laminating.

Cast phenolic resins.—The firms producing cast phenolic resins market them in sheets, rods, and tubes. The castings are made in[55] molds of lead or glass, and the range of possible shapes is limited. The consumers of these products fabricate them into finished form by cutting, turning, and polishing, much as they might fabricate wood or soft metal. Since considerable labor is required per unit, fabrication is not particularly adapted to large-scale production. In 1937 there were nine producers of cast phenolic resins. One of the smaller producers was also a fabricator of cast resins, and another a producer of raw materials used in making the resin.

Tar-acid resins for coatings.—The use of tar-acid resins in surface coatings has been overshadowed by the more rapid development of alkyd resins. Nevertheless the volume of tar-acid resins used as raw materials by varnish and lacquer manufacturers is growing rapidly. They are used in marine varnishes unmodified by other synthetic resins, but to a greater extent in combination with other plastics, especially the alkyds and nitrocellulose. The coating industry includes many units producing on a large as well as a greater number producing on a smaller scale. In general, they are not producing their own tar-acid resins. In 1937 there were 11 producers of tar acid resins for coatings (including the three largest) who confined their activities to resin production. In addition there were eight manufacturers of varnishes and lacquers and one producer of resin raw materials, who also produced tar-acid resins for use in coatings.

Tar-acid resins for miscellaneous uses.—The chief uses for tar-acid resins other than for molding, casting, laminating, and in coatings are as a bonding material, and as an adhesive. These resins form a valuable bonding agent for asbestos in brake linings and chemical tanks, for abrasives and for ground cork in special uses. As an adhesive they are used in making moisture-resistant plywood.

In 1937 there were five producers of tar-acid resins for miscellaneous uses, including the largest, who confined their activities to the making of resins and two, including the second largest, who also made products in which these resins were consumed.

Alkyd resins made from phthalic anhydride.—The rapid increase in the production of alkyd resins for use in coatings is one of the most remarkable in the whole resin industry. They go into varnishes, lacquers, and enamels for spraying, brushing, and dipping. The coatings may be air-dried, with a wide range of drying time, or dried by oven baking. The volume of alkyd resins used by the coating industry has grown so large that a number of coating firms have gone into the production of alkyds and now make part or all of their own requirements. In 1937 there were 24 paint, varnish, and lacquer firms producing alkyd resins. Included in this number were the first and second largest producers of such resins. Eleven producers of these resins, including the third and fourth largest, made alkyd resins for sale only. Each of these groups included one firm which also made phthalic anhydride.

Alkyd resins made from maleic anhydride.—In 1937 there were seven producers of alkyd resins from maleic anhydride who produced for sale only. This group included the two largest producers and also one firm which produced maleic anhydride. In addition there were five paint, varnish, and lacquer firms producing part or all of their needs of resins of this type. The general conditions under which these resins are consumed are the same as for alkyd resins made from phthalic anhydride.

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Urea resins for molding.—The conditions under which urea resins are molded are not greatly different from those already discussed for tar-acid resins. The molding cycle is somewhat longer and, because of the light colors used, special precautions must be taken to prevent discoloration of the molded product by dirt or flecks of molding powder from other operations, carried through the air or upon the person of the laborer. In 1937 there were four producers of urea resins for molding. Three of them, including the two largest, produced for sale only; the other consumed his own production.

Urea resins for other uses.—Until recently urea resins were thought of exclusively for molding, but they are now being used for laminating, for surface coatings, and also as an adhesive. Ordinarily the ureas are used only in impregnating the outside laminae of a laminated sheet where they are valuable for the light colors they make possible. The volume of urea resins used in surface coatings is small compared with the alkyd or tar-acid resins used for this purpose, but is increasing. The use of urea resins in adhesives is still new but promises to become important.

In 1937 there were four producers of the ureas for uses other than molding, who produced for sale only; and two producers who consumed their own product.

Coumarone and indene resins.—Coumarone and indene resins are produced in connection with the production of solvent naphtha. There were three producers in 1937, all of whom sold their product. These resins go into varnishes, where they replace natural resins or ester gum.

Other resins.—In 1937 there were four producers of vinyl resins in the United States, and two of these also produced their raw materials. The vinyl resins were used chiefly in surface coatings, molding, and in safety glass. The polystyrene resins, used chiefly for molding and laminating, were offered by two producers for the first time in 1937. Two other producers offered acrylate resins, which are cast, molded, or used in surface coatings. In the same year petroleum resins were sold in good volume, their only producer obtaining them as a byproduct of the oil industry.

Relationship of the resin industry to other industries.

The term “synthetic resin industry” is a very broad one, referring in reality to a group of industries producing the varied synthetic resins—much as the term “steel industry” includes the manufacture of pig iron, structural steel, tin plate, and wire. But it is interesting to examine briefly the connection of the synthetic resin industry with some of the other large industrial groupings.

Relationship to the chemical industry.—Since the processes involved in the production of the synthetic resins are essentially of a chemical nature, the whole industry might be legitimately classed as a branch of the chemical industry. Historically, the synthetic resin industry in the United States developed outside of the chemical industry as it was constituted at the time, but with the passage of years and the development of a greater variety of resins the connections have multiplied. Chemical companies supply some of the important raw materials for synthetic resins; their skilled experts possess the technical training to develop new resin processes; their research programs from time to time lead to the discovery of valuable facts regarding[57] resin; and they possess, or can, more easily than a new company, obtain the capital necessary to exploit a process.

At present the interest of the large chemical corporations in synthetic resins ranges from active participation to apparent indifference; but the growing number of corporations thought of as chemical which are now engaged in experimental production would seem to indicate that in time they will be increasingly important in the production of synthetic resins. Some of the larger chemical companies that are important producers of synthetic resins in 1938 are:

Relationship to the surface coating industry.—The use of tar-acid, alkyd, urea, and vinyl resins as raw material for the surface coating industry has already been mentioned, and also the fact that the coating industry is manufacturing a substantial part of its consumption of alkyd resins.

At present the synthetic resins go chiefly into varnishes, lacquers, and enamels for inside use and into finishes for outside use on metal. Now that coatings incorporating synthetic resins are successfully adapted to outside finishes on wood, the incentive for the production of resins by the coating industry will presumably increase because of the large volume of house paints sold.

Relationship to the electric industry.—The electric industry offered one of the first large markets for synthetic resin products. Molded and laminated parts for appliances and fixtures gave good insulation at ordinary voltages, and frequently allowed a simplification of the design. This development, coming at a time of rapid expansion in the manufacture of electric equipment, was a distinct benefit to both the electrical and synthetic resin industries. The larger electrical manufacturing firms soon began to do their own molding and laminating and became important as custom molders. Later the General Electric Co. and the Westinghouse Electric & Manufacturing Co. manufactured their own tar-acid resins.

Another important outlet for synthetic resins appeared with the development of the radio industry. Radio now offers a market for special synthetic resins possessing high dielectric constants at radio frequencies, and much larger volumes of tar-acid and urea resins are used in molding the smaller cabinets. As a rule the radio industry purchases its resin products already molded to order.

The relationship to the auto industry.—The automobile manufacturing industry and makers of automobile parts together furnish a substantial market for synthetic resins. In general, the automobile manufacturers purchase parts made of resin, already fabricated; parts makers usually purchase the resins they require. The Ford Motor Co. makes tar-acid resins for its own use. Working parts, such as timer heads and horn buttons, are usually of molding tar acid resin; the timing gear usually of laminated tar-acid resin. For decorative parts, such as dash instrument knobs and radiator ornaments, urea and cast phenolic resins have been used. Most of these parts are small, but altogether they have taken a substantial volume of synthetic resin. Safety glass for automobile windshields is now being made from vinyl resin.

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The future possibilities are difficult to appraise. The automobile industry is constantly experimenting with new materials and methods, and its policy of bringing out models annually makes possible rapid adoption of new developments. Molded window frames have been tried, and such a use, or use for the complete instrument panel, would obviously consume synthetic resins in much larger volume. Even whole motor car bodies of laminated resin have been suggested.

Synthetic resins enter into the foreign trade of the United States only to a small extent. This becomes apparent if a comparison is made between the United States production of these resins and our imports and exports of them. Table 13 gives the imports and production of synthetic resins in the United States for 1934 through 1937. Exports are so small that they are not separately reported.

Table 13.—Synthetic resins: United States production and imports, 1934-37

The small size of the international trade in synthetic resins is also emphasized if we compare the imports of all synthetic resins with the imports or exports of some of the important raw materials used in their manufacture. Table 14 makes such a comparison.

Table 14.—Comparison of international trade of the United States in synthetic resins and in certain raw materials for resins, 1934-37

There are three factors that together largely account for the small size of our foreign trade in synthetic resins. As a result of the comparative youth of the resin industry, the complicated patent situation, and the substantial tariff rates upon imports of resins into the United States, domestic producers have experienced little competition from[59] abroad. The first two of these forces plus the tariff barriers of other countries have caused them to pay little attention to export markets. But it should be observed that both of the first two forces will become less important with the passage of time. When home markets have been more fully exploited, problems of production have become less pressing, and most of the basic patents on resins have expired, international trade in synthetic resins may be expected to increase from its present low levels. If this occurs, the United States, with its large scale production for the home market and with its generally favorable position with regard to the raw materials and the technical skills necessary, is more likely to become a net exporter than a net importer of synthetic resins.

Rapid expansion of business in home markets.

Being young industries and having potentially large home markets awaiting development, the synthetic resin industries in the United States naturally began by concentrating first on their numerous production problems to meet a rapidly expanding domestic demand, improving their products and devising useful applications.

The tar-acid-formaldehyde resins for molding were the first to develop. The industry producing them may be said to have started around 1910, but did not become important until after the World War, when the drop in price of phenol made the resins available at lower prices. The alkyd resins and the urea-formaldehyde resins in the United States began to be important in 1929 and 1930, respectively. The others may be said to be still in their earliest stages of development as industries, however much research work may have been done as to their properties and production.

The effect of patents on international trade.

A second factor involved in limiting international trade in resins is that relating to patents. The basic patents on tar-acid resins have expired; but while they were in force, they prevented imports into the United States. In the United States a valid patent can be enforced at law not only against domestic products which infringe but also against imports. In addition to court action, the provisions of our tariff law prohibiting unfair competition in the import trade were invoked to prevent entry of synthetic phenolic (tar-acid) resin, form C, but when the basic patent for this material expired, the exclusion order no longer applied to single color material, except in the matter of certain marking requirements.[6]

The patent situation may militate against exports as well as imports. Where a company owns foreign patents it may set up a company to exploit them abroad, or it may license their use by others. Again, mutual interest may dictate an exchange (by cross-licensing) of certain patents. International licensing of patents is usually accompanied by divisions of international markets through formal or informal understanding. Such agreements may outlive the life of the patents, especially if bolstered with financial connections. But unless the original producers continue to dominate their respective markets, any agreements between them are likely to diminish in importance, [60]because after the patents expire new competitors would have a free hand in foreign as well as domestic markets.

The original United States producer of tar-acid resins set up or licensed companies to manufacture in a number of foreign countries. The urea-formaldehyde process was developed in Europe and the first American producer was a licensee of a British corporation. Similar arrangements exist with regard to most of the other resins.

The United States tariff on resins and resin products.

Synthetic resins.—Imports of tar-acid, alkyd, coumarone and indene, styrol, adipic, and aniline resins are dutiable under the provisions of paragraph 28 of the Tariff Act of 1930, which reads in part: “synthetic phenolic resin and all resinlike products prepared from phenol, cresol, phthalic anhydride, coumarone, indene, or from any other article or material provided for in paragraph 27 [coal-tar intermediates] or [paragraph] 1651 [coal-tar crudes], all these products whether in a solid, semisolid, or liquid condition; ... 45 per centum ad valorem [based on American selling price[7] or United States value[8]] and 7 cents per pound.” Where these resins are produced in the United States, imports are “competitive” and the dutiable value is based upon American selling price. If the American selling price is higher than the foreign value, the effect of this method of valuation is to increase the duty to which imports are subject. The duty of 45 per cent ad valorem and 7 cents per pound was equivalent to 54 per cent ad valorem on the American selling price of the small imports of coal-tar resins in 1937. If it could calculated upon foreign value it would be much higher.

Synthetic resins of non-coal-tar origin, except vinyl resins, are dutiable under paragraph 11, which reads “synthetic gums and resins not specially provided for, 4 cents per pound and 30 per centum ad valorem” on foreign value. This rate was the equivalent of 48 per cent ad valorem upon the small amount of imports in 1937. The most important resins included are the urea and acrylate resins.

Between 1930 and 1936 there was some doubt whether vinyl resins were dutiable under paragraph 11 at the rate quoted or under paragraph 2 which provided for “vinyl alcohol ... homologues and polymers of all the foregoing; ethers, esters, salts and nitrogenous compounds of any of the foregoing, whether polymerized or unpolymerized, ... not specially provided for, 6 cents per pound and 30 per centum ad valorem” on foreign value. But the Canadian trade agreement, effective January 1, 1936, reduced the rate on vinyl [61]resins under either paragraph 2 or paragraph 11 to 3 cents per pound and 15 percent ad valorem.[9] The reduced rate was equivalent to 25 percent ad valorem upon the imports in 1937.

Under these rates, imports of synthetic resins, other than vinyl resins, have been insignificant.[10] After the reduction of duty, imports of vinyl resins in 1936 amounted to approximately 600,000 pounds, valued at $145,000 and in 1937 to 650,000 pounds, valued at $200,000. (See table 11.)

Articles made of synthetic resins.—Laminated products of which synthetic resin is the chief binding agent and manufactures of such products are dutiable under paragraph 1539 (b) at the following rates: 15 cents per pound and 25 percent on laminated sheets or plates[11]; 50 cents per pound and 40 percent on laminated rods, tubes, blocks, strips, blanks, or other forms; and 50 cents per pound and 40 percent on manufactures of such laminated products. Paragraph 1539 (b) also provides a duty of 50 cents per pound and 40 percent on manufactures of any other product of which any synthetic resin is the chief binding agent. These are, for the most part, molded synthetic resin articles. Paragraph 1539 (b) does not cover articles made entirely of synthetic resin (cast synthetic resin articles). Such articles unless specifically provided for in the law are dutiable under paragraph 1558 as manufactured articles, not specially provided for, at 20 percent ad valorem.

A great many articles, which are made in whole or in part of synthetic resin, are not dutiable under either paragraph 1539 (b) or paragraph 1558. These are articles which are specifically mentioned in other paragraphs and subject to the duties provided therein. Table 15 lists a number of them.

Table 15.—Tariff classification and rates of duty in Tariff Act of 1930 on certain articles made of synthetic resin

In general, the available statistics of imports do not segregate imports of the specified articles made of synthetic resin from those of the same articles made of other materials; and the same situation is true of imports of unspecified articles wholly of synthetic resin which enter under paragraph 1558. Imports of manufactured articles, n. s. p. f. in which synthetic resin is the chief binding agent [62]under paragraph 1539 have been small. Figures for recent years are given in table 16.

Table 16.—Manufactured articles n. s. p. f. in which synthetic resin is the chief binding agent: United States imports for consumption, 1931-37

Synthetic resins as substitutes.

Any new material will in the course of time be applied to the uses for which it has special advantages, displacing older materials which formerly served those purposes. The resulting product may sometimes be used in the same manner as before, or the properties of the substitute material may widen the usefulness of the finished product, or even make possible a product almost wholly new.

Before the development of molded synthetic resins, electrical plugs and sockets were usually made of porcelain or molded of marble dust and shellac. In this use substitution has been almost complete. Wall plates for electric switches and outlets were usually of brass. Today molded tar-acid or molded urea resins are substituted in part. In neither of these examples has the substituted material any important effect upon the use of the product.

An example of a substitute material widening the usefulness of the product is afforded by a new computing scale, where a molded urea resin casing (substituted for metal in the older model) has aided in decreasing the weight and has improved the appearance. Another example is the use of laminated synthetic resin coil forms in radio frequency transformers which, because of their better electrical properties at high frequencies, have aided in the design of more compact units.

Examples of synthetic resins making possible a wholly new product are more difficult to find, but the following will serve as illustrations: Cast acrylate sheets to form curved cockpit enclosures for airplanes; molded acrylate buttons for reflecting road markers; and new special coatings, which make possible the use of metal cans for preserving foods and beverages hitherto impossible to can without loss of flavor.

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Motives for substitution.

One of the most important reasons why a manufacturer may decide to substitute a synthetic resin for another material is the resulting economy in the sense of economy in total costs. As a rule, the synthetic resin will be more expensive pound for pound than the material for which it is substituted; but frequently the manufacturing cost is enough lower to more than make good the difference in material cost, because the resin part will come from the mold almost in finished form, whereas the part made of wood or metal will require considerable fabrication. In some cases there may be a saving in marketing costs. For example, the shades for large office fixture lights are now made of synthetic resin as well as of opal glass. The resin shades are less expensive to ship because they are lighter and require less expensive packing.

Another incentive toward substitution is to give novelty, and hence sales appeal, to an old product. In many cases the use of synthetic resins fits in with the present tendency to redesign an old-style product so that it will be more compact, have more pleasing lines, and more color.

Still another incentive toward substitution is to give the product greater usefulness, or lower costs in use. The great expansion in the use of synthetic resins in surface coatings has come about because, with these materials, coatings can be developed to fit special purposes, and dry rapidly, which means an important saving to those who use them.

Materials displaced by synthetic resins.

The wide range of uses to which synthetic resins are now applied implies that the materials displaced are numerous. For example, cast or wrought iron or steel is displaced in timing gears and in many small machine parts, such as cradle-type telephones; nonferrous metals in small machine parts and novelties, such as inexpensive bracelets; glass in lamp shades and in cosmetic containers; natural resins in lacquers; plastics, such as cellulose acetate in safety glass or cellulose nitrate in colored lacquers; other adhesives in bonding plywood; and cork or metal in bottle closures.

In general, the quantity of material displaced is a very small part of that material’s total market. Frequently, however, industries producing the finished product have had to make substantial changes in their equipment in order to use synthetic resins. This has been true in the button industry, in the bottle closure industry, in the varnish and lacquer industry, and in the various electrical supply industries; and readjustment is now proceeding in the fancy container industry and in the safety glass industry.

Competition between synthetic resins.

Any particular synthetic resin must compete for its market with other synthetic resins, as well as with other materials. The basis of choice or substitution will be the same as that which has already been briefly discussed in connection with the displacement of other materials by resins. As between a number of resins with properties fitting them for a particular use, the total costs of using each will be compared and the choice will go to the least expensive; but where a resin has special advantages in a particular use it may win out over a less expensive resin.

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It should be emphasized that this battle of materials for markets is a never-ending one. The fact that a specific synthetic resin has achieved a certain position is no guarantee that it may not lose it wholly or in part to some newer resin or other material. Thus cast phenolic resin was for a time the only resin available in light colors but urea resins became available in pastel shades and more recently water-clear polystyrene and acrylate resins have come on the market. Until recently tar-acid resins were without competition in laminating, but urea resins now are used to some extent for the surface laminae and the tar-acid resins now face a potential threat in a new product offered to laminators. If the use of this cellulose sheet, which looks much like blotting paper and which has lignin incorporated in it to act as a binder in the press, should materially decrease the cost of laminated sheets, it will mean serious new competition for the tar-acid laminating resins.

The general effect of the increase in number of types of synthetic resin has been to modify the market outlook of the producers of each type. They are now more inclined to view the market as being limited by the price at which they can supply their product and by the physical properties of each resin rather than attempt to exploit it as a universal resin for all purposes.

Resins classified by cost.

At present the resins produced in largest volume are the alkyd resins for use in surface coatings; the tar-acid resins for molding, laminating, and surface coatings; the urea resins, chiefly for moldings; and the cast phenolic resins. Roughly, the price per pound of pure resin material[12] for these various resins may be compared as follows:

Because the cost of the filler is less per pound than the cost of the resin, the cost of the tar-acid and urea molding powders will be less than the figures given for the pure resin. On the other hand, wholesale prices paid by consumers will include transportation and distribution costs not included in the figures of manufacturers’ sales.

Vinyl resins, acrylate resins, and polystyrene resins are at present produced in much smaller volume than those just listed. If and when the volume of production is increased the price may be decreased. In 1937, the price per pound of pure resin[12] was as follows:

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Early in 1938, acrylate resins were being offered for sale at 85 cents per pound for molding powder and $1.25 per pound for the cast material; polystyrene resins at 72 cents per pound.

Petroleum resins, in 1937, sold for an average of 2 cents per pound net resin content.[12] This low price puts them beyond competition of the other synthetic resins in the uses in laminating and coating to which they are adapted.

The physical properties of a resin and its uses.

A more expensive resin will be used in preference to a cheaper one, only if the higher cost is more than offset by some physical property, such as color, which makes it more desirable in a particular use. The most common molding resin at present is the tar-acid type, but it is available only in the darker colors and therefore has been at a disadvantage, where a light color is desired, in competition with cellulose nitrate (celluloid) and cellulose acetate plastics or with urea and cast phenolic resins. In recent years the production of cellulose acetate molding compounds and of urea resins has increased rapidly, largely under this stimulus. The desire for color also promises well for the future of the acrylate and polystyrene resins which are produced in water-clear grades or colored with dyes or pigments.

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Table 17.—Synthetic resins and other plastics: Properties that affect appearance

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Table 18.—Synthetic resins and other plastics: Molding properties

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Table 17 lists the properties which affect appearance and gives in addition to the color range, the clarity, material, the burning rate, the effect of age and sunlight, the refractive index, and the machining quality of each synthetic resin.

Table 18 lists molding properties of synthetic resins. Of special interest are the possibilities of using a resin in injection molding. The thermoplastic resins and plastics (see softening point in table 20) are generally preferred to the thermosetting materials for injection molding because they permit the reuse of material otherwise wasted.

Table 19 lists the strength properties of the synthetic resins; table 20 the heat properties; table 21 the electrical properties; and table 22 the resistance to acids, alkalies, and solvents. All of these qualities are important in some uses and each quality may be paramount in a few. Each material has its limitations and its special advantages and the consuming industry must choose the one best suited to its purposes. The tie-up between specific properties and particular uses is exemplified by vinyl resins, which because of their great elasticity at low temperatures, are used in safety glass, and by the polystyrene resins, which because of their electrical properties at high frequencies, are used in laminated electrical parts. As production of the various resins increases new uses will probably be found for most of them.

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Table 19.—Synthetic resins and other plastics: Strength properties

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Table 20.—Synthetic resins and other plastics: Heat properties

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Table 21.—Synthetic resins and other plastics: Electrical properties

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Table 22.—Synthetic resins and other plastics: Specific gravity, specific volume, and resistance to other substances

Large-scale production of synthetic resins is confined principally to the United States, Germany, and Great Britain. There is small production in many other countries, of which the most important are France, Italy, Czechoslovakia, Canada, and Japan.

In 1934 the world output was estimated at 135 million pounds, of which the United States produced about 44 percent, Germany 26 percent, and Great Britain 24 percent. In 1937 world output was estimated at 360 million pounds, the United States’ share of the total being almost 50 percent, followed by 27 percent for Germany, 20 percent for Great Britain, and the remaining 3 percent scattered.

European estimates indicate that about 40 percent of the output goes into surface coatings and that 60 percent of the surface-coating resins are tar-acid and 40 percent alkyds. The Tariff Commission found that in 1937 50 percent of the United States production of all synthetic resins went into surface coatings, 27 percent into molded articles, and the remaining 23 percent into laminating and miscellaneous uses. Approximately three-fourths of the surface-coating resins were alkyds and one-fourth tar-acid resins.

GERMANY

Production.

In recent years Germany’s production of synthetic resins has increased rapidly, each succeeding year registering the attainment of a new record. In 1933 production totaled 17,500,000 pounds and by 1935 had increased to 55,000,000 pounds. A further expansion of about 30 percent to 70,000,000 pounds in 1936 and present production trends indicate a gain of about 40 percent more in 1937, to an estimated total of 100,000,000 pounds.

Although tar-acid resins comprise the bulk of the German output, considerable gains are shown for other types, notably injection molding resins of the polystyrene and vinyl types. The development of completely automatic injection molding machinery has given an impetus to these types. While technical progress, including improvement of molding equipment, has contributed to the expanded production, the use of synthetic resins in Germany has had a strong stimulus because they are made almost wholly of domestic materials. Under the “Four-Year Plan” for the greatest possible national economic independence, synthetic resins are replacing imported materials, such as the heavier nonferrous metals, iron, hardwoods, cork, and natural gums and resins in many uses. This displacement of materials has also affected such domestic products as glass and porcelain, which caused the Government to intervene and impose restrictions upon the use of resins for purposes adequately served by other materials of German origin.

Germany’s expanding production of synthetic resin has also been aided by a sharp increase in exports, which have increased well over 100 percent since 1932.

Tar-acid resins.—German output of tar-acid resins has been estimated at 35 million pounds in 1934, at 49 million pounds in 1935, and at 63 million pounds in 1936. Such resins comprise the bulk of the German production of molding resins.

There are at least seven producers of tar-acid resins in Germany and nine producers of molding powders and pellets. Tar-acid resins[76] for surface coatings are produced by a number of these concerns. Among the important makers in Germany are The Bakelite Gesellschaft (organized in 1910 to operate under the Baekeland patents); the explosives and munitions firm of Dynamit A.G.; Dr. Kurt Albert G.m.b.H.; the I.G. Farbenindustrie; Beckacite Kunstharzfabrik G.m.b.H.; and Rohm & Haas A.G. The Beckacite firm has associates in the United States and in the United Kingdom, and Rohm & Haas, an associate in the United States.

Alkyd resins.—The manufacture of alkyd resins has developed in Germany in the past few years. Demand for these resins has been given a marked impetus by the development of a new standardized substitute for linseed-oil varnish known as El Varnish, the use of which is required by the Control Board for Industrial Fats for certain interior and exterior painting.

There are five makers of resins for paints, varnishes, and lacquers. The output of alkyd resins has increased sharply since 1934, probably reaching 10 million pounds in 1936.

Urea resins.—The output of urea resins in Germany is relatively small; two of the more important types are known as Locron and Pollopas.

Polystyrene and vinyl resins.—In 1936 Germany’s production of thermoplastic resins exceeded 1 million pounds, principally of the polystyrene and vinyl types. Among the vinyl resins are Acronal and Mowilith, both of which are manufactured by the I.G. Farbenindustrie. This combine also produces several types of polystyrene resins known as Mollit and Metastyrol. Dynamit A.G. produces a polystyrene resin known as Trolitul.

Uses of synthetic resins.

The original and most important use of synthetic resins in Germany was for electrical insulation. This use was so extensive that the industry was organized in 1924 into an association known as non-rubber insulation materials industry. Materials were standardized and classified into 14 types, of which 5 were tar-acid resins and 1 was a urea resin. Every type must meet certain specifications in order to be recognized by the Reich Testing Institute. More than 100 firms produce insulating materials meeting the institute’s specifications.

Radio panels of the popular sets sponsored by the Government are made of synthetic resins. Consumption in the automobile industry is increasing for such parts as instrument panels, electrical equipment, steering wheels, gear-shift knobs, and numerous others. The latest airplanes show increased use of synthetic resins, where they contribute light weight, great strength, and resistance to corrosion.

In cameras and moving-picture equipment, wood and metal have been in part replaced by synthetic resins. Other applications of resins in Germany include bearings for rolling mills, goggles and spectacles (including the lens), and perfume and medicine bottles.

Resins for surface coatings are undergoing rapid development in Germany, owing to the shortage of linseed oil. Alkyd resins in coatings are being promoted by the Government, which prohibits or limits the use of the older oil-type coatings for certain uses so as to decrease the use of linseed oil and other paint oils that must be imported[77] and hence require outlays of foreign exchange. Penalties have been imposed for violating the regulations.[13]

Organization.

The synthetic-resin industry in Germany is a unit within the national industrial organization. It is a subdivision of the industrial chemical group, called Fachgruppe Kunststoffe, or Group 13 of the 19 trade groups in the chemical division. This subdivision controls casein and cellulose plastics as well as synthetic resins, and is further divided as follows: (1) Casein plastics, (2) cast phenolic resins, (3) molding compositions, (4) resins for lacquers, (5) celluloid and zellon, (6) transparent sheeting, (7) linoleum, and (8) miscellaneous (such as vulcanized fiber, bottle caps, and die-casting resins).

There are two cartels distinct from the national organization, which expressly excludes all functions and activities of cartels. One cartel represents the firms interested in molding compositions and the other those interested in synthetic resins for other purposes. Some of the producers are members of both cartels.

Foreign trade.

Imports of synthetic resins are negligible, although the duty of 4.6 cents per pound (25 marks per 100 kilograms) on imports into Germany is not prohibitive. Exports have increased practically every year since 1930, when they were first recorded separately.

Table 23 shows the quantity and value of exports in recent years.

Table 23.—Synthetic resins: German exports, 1930-37

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German exports of synthetic resins are, for the most part, destined to European countries, most of which have increased their purchases considerably in recent years. Exports to Latin American countries have increased recently, especially to Brazil. Table 24 shows the distribution of exports in recent years.

Table 24.—Synthetic resins: German exports, by countries, 1934-37

GREAT BRITAIN[14]

As in most other countries, the history of the synthetic-resin industry in Great Britain begins with the acquisition of rights by a British concern to manufacture under the original Bakelite patents. The Damard Lacquer Co., Ltd. was probably the pioneer maker of phenolic resins in England. The principal product was a baking lacquer sold under the trade name Damarda, marketed for and used principally as a coating to prevent corrosion on brass. The outbreak of the World War created such an urgent demand for laminated materials that this firm started production of them for the British Government. In 1926 this concern was merged with Mouldesite, Ltd. and Redmanol, Ltd., under the name of Bakelite, Ltd.

Production.

Statistics of production of synthetic resins in Great Britain are available only for 1934 and 1935. They are given in table 25.

Table 25.—Synthetic resins: Production in Great Britain, 1934 and 1935

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Capital invested in the British industry is reported as 15,000,000 pounds sterling and direct employment as 20,000 people.

Tar-acid resins.—Many large moldings are made in England, such as large radio cases, desk files, trays, and drain boards. Cast phenolic resin production has just been started in England.

Among the novelties recently produced in England is a toy railway molded of tar-acid resin. The trains and track spacers are of nonconducting resin; the molded rails are made conductive by a thin covering of metal which is pressed in and secured at the ends. Two trains may be run on the same set of rails at different speeds, or one can go forward and another backward, since the two outer rails are separate conductors, the third rail acting as a common return.

Molded piano parts are being tried in an attempt to solve the troubles hitherto encountered with wood, owing to variations in humidity. Resins have long been used in facing the keys, but the production of piano action parts has presented many technical difficulties. The secret of success with molded resin parts lies in molding the joints in position when the main body is molded. There are 88 sections in each piano.

Urea resins.—British Cyanides, Ltd., well-known makers of synthetic resins in England, acquired the Pollopas patents for the manufacture of urea resins in the United Kingdom, in certain continental European countries, and in the British Empire except Canada. The agreement called for a full exchange of patents and other information with the other licensees of the Pollopas patents. These arrangements were made for the purpose of consolidating the patent position and for the pooling of technical data already existing on manufacture, with the object of improving quality.

Acrylate resins.—An outstanding development in Great Britain has been the production of the thermoplastic resins known as Diakon and Perspex. These are made from methyl methacrylate and are developments of the Imperial Chemical Industries, Ltd. Diakon is for molding powders and Perspex is in the form of cast sheets, rods, tubes, and optical forms.

These new commercial resins are considered the best combination thus far obtained of strength, transparency, and light weight. Applications in England include fittings for aircraft, transparent inspection covers for machinery, medical equipment, instrument windows, lenses and prisms in optical systems, and aircraft windscreens. They are used in subways for lenses for deflecting and diffusing light and in battery cases and coil forms.

The general properties of the acrylate resins include transparency to both visible and ultraviolet light, almost unlimited color range, resistance to acids and alkalies, and superior electrical properties.

Aniline resin.—Panilax is an aniline-formaldehyde condensation product made in England. It has high electrical and thermal insulating properties, great mechanical strength, is odorless and odor repelling, and practically unaffected by water, oil, and alkalies.

Organization.

Most of the British producers of synthetic resins are members of the British Plastics Federation, Ltd.

Several years ago a 10-year contract was made between the Imperial Chemical Industries, Ltd. and the Toledo Synthetic Products[80] Co. (now Plaskon Co.) of Toledo, Ohio. This agreement provides for an exchange of all technical and commercial information on urea-resin products and processes and the granting of free licenses under present or future patents.

Agreements probably also exist between the British Bakelite Co. and the American firm on tar-acid resins; between Nobel Chemical Finishes, Ltd. and E. I. du Pont de Nemours & Co. on alkyd resins; between British Thompson Houston Co., Ltd., and the General Electric Co. on alkyd resins; between Imperial Chemical Industries, Ltd. and du Pont on acrylate resins; and between Beetle Products Co. and American Cyanamid Co. on urea resins.

Foreign trade in resins.

British imports of synthetic resins, by principal sources, are shown in table 26.

Table 26.—Synthetic resins: Imports into the United Kingdom, in selected years, 1930-36

British exports of synthetic resins to principal countries are shown in table 27.

Table 27.—Synthetic resins: Exports from the United Kingdom, in selected years, 1930-36

FRANCE[15]

Producers.

Statistics of French production and sales of synthetic resin are not available. Larousse Commercial Illustré describes the French synthetic resin industry as not important and estimates the output in

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1930 at 2,000,000 pounds. The Revue Général des Matières Plastiques, most important technical review in France, estimates the production in 1931 as about 3,500,000 pounds.

The comparatively few French companies producing synthetic resins are, for the most part, under British or German control. The types of synthetic resin made in France, the trade names, and the names of the manufacturers, follow:

Bakelite.—Tar-acid molding compounds and laminating materials; cast phenolic resins; Cie La Bakelite, Bezous, Seine.

Plastose and Ferodo.—Tar-acid molding compounds; Société Ferodo-Plastose, Saint Ouen, Seine.

Pollopas.—Urea molding compounds and laminating materials; Établissements Kuhlmann, Paris.

Foreign trade.

French imports of synthetic resins are classified under tariff item No. 0376 bis: Synthetic resins (solid or resinous products of the Bakelite, Albertol, Plastose types, etc.) derived from the condensation of aldehydes with phenols, amines, and amides. Several subclassifications are shown: (a) Soluble in oil and not polymerizable, (b) which may be rendered insoluble and infusible, and (c) infusible. Imports in recent years, from principal sources, are shown in table 28.

Table 28.—Synthetic resins: French imports, by types and by countries, 1931 and 1933-37

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Exports of synthetic resins from France, by principal markets, are shown in table 29.

Table 29.—Synthetic resins: French exports 1931 and 1933-37

CZECHOSLOVAKIA

Production of phenolic resins in Czechoslovakia has increased rapidly in recent years and is ample to supply domestic requirements. Most of the raw materials are imported from Germany, Great Britain, and France, but formaldehyde is produced locally in sufficient quantities.

The principal makers of synthetic resins in Czechoslovakia are:

Resin products are widely used by the electrical industries for wall plates, plugs, switches, fuse boxes, etc. Other articles made of synthetic resins are: handles and knobs for furniture and kitchen equipment, bottle caps, fountain pens and pencils, clock and radio housings, tableware, cutlery handles, trays, buttons, toilet ware and toys.

Imports of synthetic resins in 1934 totaled 1,270,500 pounds; Germany supplied 46 percent and Great Britain 22 percent of this total. Exports of synthetic resins during the same year amounted to 166,540 pounds and went principally to Poland, Yugoslavia, Germany, and Argentina.

ITALY

The Societa Italiana Resine, an affiliate of the important chemical firm, Chimiche Forestali, is a leading maker of tar-acid resins in Italy. A new and modern plant is located at Milan in close proximity to the electrical and textile industries, both important markets for resins.

In 1936 the Ministry of Corporations granted Montecatini Societe Generale per l’Industria Mineraria, Milan, a permit to develop a factory for alkyd resins; and also Societe Italiana Ebonite and Sostituti, Milan, one to produce tar-acid resins. In 1937 a permit was granted to Montecatini S.A. for a plant to manufacture acrylic acid resins at the Villadossola works of the Soc. Elletrochimica del Toce.

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JAPAN[16]

The history of the synthetic resin industry in Japan goes back to 1913 when Dr. Jokichi Takamine, discoverer of adrenalin and takadiastase, acquired the right to manufacture and sell tar-acid resin Products in Japan. The business was financed by the Sankyo Co., Ltd., and a factory was built at Shinagawa, near Tokyo. In 1923 a subsidiary company known as the Japan Bakelite Co., Ltd., was formed with a paid-in capital of 1,200,000 yen. This firm considers itself an affiliate of the Bakelite Corporation of the United States and, according to an existing agreement, cannot export to the United States. Its territory includes the Japanese Empire and Manchukuo. China is considered an open market.

The original plant at Shinagawa was partially destroyed by fire in 1919, and the following year was moved to Mukojima, Tokyo. The firm makes tar-acid resins, and a full line of products covered by the patents of the American concern. Included are laminated sheets, molding compounds, molded articles, surface coating resins, laminated resin gears and spindles for rayon mills. An interesting development is the adaption of tar-acid resin lacquers to the production of Japanese lacquer ware such as bowls, vases, etc.

Since the establishment of the Japan Bakelite Co., several other firms have started the production of synthetic resins. The Tokyo Electric Co., an affiliate of the General Electric Co., makes tar-acid resins under the trade name Tecolite. Products are used principally for insulation, although molding compositions and molded articles such as are used by the electrical trade are commercially produced.

The Matsushita Electrical Works at Osaka are producers of tar-acid resins and articles made therefrom. The output is used largely for radio and electrical equipment. The Nissholite Manufacturing Co., Ltd., with a factory at Yasui-cho, Uzumasa, Kyoto specializes in decorative laminated material sold under the trade name Nissholite. The Japan Nitrogenous Fertilizer Co. (Nippon Chisso Hirijo Kabushiki Kaisha) is an important maker of tar-acid resins, marketing them under the trade names Chissolite, Safeloid, and Minaloid. The Yokahama Resin Co., a relatively small company, produces tar-acid resins and markets them in the form of molding powders. The firms listed account for practically all of the Japanese production of synthetic resins and for about 50 percent of the molded articles made from them. The remaining 50 percent of the output of molded articles is made by a large number of small firms, the majority being household industries. It is reported that there are about 2,000 of these so-called plants already engaged in this relatively new industry.

Production.

The Japanese production of manufactures of tar-acid resin reported by the Department of Commerce and Industry is shown in table 30. These data include the output of plants employing more than five operators and apparently account for only half of the total.

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Table 30.—Manufactures of tar-acid resins: Production in Japan, 1929-35

Estimates from other sources of Japanese productions of tar-acid resins indicate an output of 2,600,000 pounds of resin and 3,600,000 pounds of molded resin articles in 1933, and of 4,900,000 pounds of resin and 7,500,000 pounds of resin articles in 1935.

It was recently announced that the Gosei Chemical Co. will manufacture vinyl resins in Japan. This firm’s principal interest is in acetate fiber and rayon manufacture. Later in 1936 the Showa Fertilizer Co. announced the successful development of a process for making urea. Urea resins are in commercial production by the Toyo Gosei Kagaku Kogyo K.K., an affiliate of Chugoku Toyo K.K.

The resin industry in Japan is expected to undergo considerable development in the near future. Raw materials are available in sufficient quantities and the art of molding is fairly well developed.

CANADA

The producers of synthetic resins in Canada are:

The Bakelite Corporation of Canada, Ltd., an affiliate of the firm of the same name in the United States, was formed in 1925. This plant makes molding materials, laminating materials, and an extensive line of technical varnishes. Molded parts were made at this factory until 1932.

Shawinigan Chemicals, Ltd. is the pioneer organic chemical maker in Canada. A modern plant at Shawinigan Falls, Quebec, produces synthetic acetic acid, acetaldehyde, vinyl acetate, vinyl resins, and other chemicals. The vinyl resins manufactured by this firm have already been described (see p. 44). Appreciable quantities of these resins have been exported to the United States in the past but the construction of a factory (jointly owned by Shawinigan Chemicals, Ltd., and the Fiberloid Corporation) at Indian Orchard, Mass., for the manufacture of vinyl resins will probably result in a decrease of exports from Canada to the United States.

The Canadian General Electric Co. makes alkyd resins for use in surface coatings. Phthalic anhydride and other raw materials are[85] imported from the United States. Canadian Industries, Ltd., produces alkyd resins at a plant in Toronto, Ontario.

There are about 14 molders of synthetic resins in Canada, of which all but 3 are in Ontario. These firms make a general line of molded articles including electrical articles, closures, costume jewelry, and smokers’ accessories. Appreciable quantities of molded articles are imported from the United States and smaller quantities from Germany.

UNION OF SOVIET SOCIALIST REPUBLICS

The synthetic resin industry in the Union of Soviet Socialist Republics is concentrated in two public departments, known as Public Commissariates: (a) Public Department for Heavy Industry and (b) Public Department for Light Industry.

The Department for Heavy Industry, known as Soyuzchemplastmass, controls the following plants:

1. Karbolit-pawod in Ljubatschani, producing tar-acid resin laminated fabric known as Textolite.

2. Karbolit-stroj in Ljubatschani, making cast phenolic resins.

3. Karbolitni-pawer in Dubrowka, making tar-acid resin molding compounds. This plant has at least 350 molding presses producing electrical parts and automotive parts. The number of presses was to have been increased to 1,000 in 1937.

4. Komsomolskaja prawda in Leningrad manufactures articles, including phone sets, from cast phenolic resins.

5. Ochtenski Chimkombinat in Ochta. This plant makes nitrocellulose plastics. No information could be obtained by our Chargé d’Affaires at Moscow concerning its production of synthetic resins, although it is believed to be considerable.

The Department for Light Industry has a resin section known as Mosplastmass producing casein plastics only.

THE NETHERLANDS

There has been no production of synthetic resins in the Netherlands; but a plant is under construction (October 1937) at Groningen for the manufacture of alkyd resins. The manufacture of surface coating and electrical parts from imported resins is carried on, chiefly by N. V. Philips’ Gloeilampenfabrieken, Afdeeling Inkoop, Eindhaven, manufacturers of radios, filament lamps, and electrical appliances. Efforts are being made to employ resins for other purposes, such as the bonding of plywood and the manufacture of closures and novelties, but little has been accomplished thus far. The relatively high cost of the resins is the principal difficulty. Molding compounds and laminated sheets, rods, and tubes are imported from Germany, Great Britain, Austria, and the United States.

The paint, varnish, and lacquer industry in the Netherlands has been experimenting with synthetic resins for several years. Alkyd resins of the glycerol phthalate type are being used by Dutch paint makers, imported principally from Germany and Austria. In spite of high cost, they have been found to have many advantages, especially better and more uniform quality. The prices of gums and resins in the Netherlands during the latter part of 1936 are shown in table 31.

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Table 31.—Prices of gums and resins in the Netherlands, 1936

The Dutch aviation industry is using tar-acid resins to bond plywood for wing surfacing on Fokker-type wooden planes. The advantages obtained are excellent adhesiveness and resistance to moisture and temperature changes. In this application they have replaced casein.

Germany supplies more than 85 percent of the Netherland imports of synthetic resins, as shown in table 32.

Table 32.—Synthetic resins: Netherland imports by countries, 1931 and 1933-37

DENMARK

The annual output of synthetic resins in Denmark is about 500,000 pounds, almost entirely of the tar-acid type.

Bakelite is produced by the Nordiske Kabel and Traadfabrikker A. S. Fabrikvej at Copenhagen. Other brands made in Denmark are Nokait, Helomit, and Etronit. There are 14 manufacturers of finished products, making electrical equipment principally.

POLAND

Production of synthetic resins in Poland in 1936 totaled 660,000 pounds, entirely of the tar-acid type.

The alkyd resins are made chiefly from phthalic anhydride and glycerin. Phthalic anhydride in turn is made from naphthalene. Polybasic acids such as maleic, succinic, etc., may also be used with glycerin to form alkyd resins. Naphthalene, phthalic anhydride, maleic and other polybasic acids, and glycerin are discussed in the order named.

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NAPHTHALENE

The discovery of naphthalene in coal tar was made simultaneously by Garden and Brande in 1819, and its composition was determined by Faraday in 1826 and later by Laurent in 1832. Naphthalene is almost invariably a constituent of the products obtained when organic matter is heated to comparatively high temperatures. For example, it is formed in small quantities when acetylene, alcohol, acetic acid, benzene, or toluene are heated to high temperatures. Together with certain aromatic hydrocarbons it is formed in the cracking of petroleum and in the hydrogenation of petroleum fractions. Naphthalene is a constituent of the principal varieties of tar produced from coal in the manufacture of gas and coke under ordinary conditions, but not of low-temperature tar. It is present in coal gas although its presence must be kept as low as possible to avoid blocking service pipes in cold weather. The proportion in gas tar varies with the kinds of coal used and is greater the higher the temperature used during carbonization; it usually amounts to 4 to 6 percent but is sometimes as much as 10 percent. In tars obtained from byproduct coke ovens the proportion of naphthalene and other aromatic hydrocarbons depends on the type of oven used. Byproduct coke-oven tar averages 10 to 11 percent naphthalene; blast-furnace tar contains only very small amounts.

Processes to synthesize naphthalene were described as early as 1873 by Aronheim, in 1876 by Wroden and Znatowicz, and in 1884 by Baeyer and Perkin. English Patent No. 26,061 of 1898 claims that it may be obtained by heating barium carbide with barium hydroxide to a high temperature. None of these processes has become of commercial importance.

Recovery of naphthalene.

Naphthalene is recovered in the distillation of coal tar, in the fraction boiling at 180° to 250° C., in the creosote oil fraction boiling at 240° to 270° C. and most abundantly in the carbolate or middle oil fraction boiling at 200° to 250° C. When these fractions are allowed to cool most of the naphthalene crystallizes out and is separated by draining and hot-pressing. This crude material is partially purified by washing with hot caustic soda solution to remove tar acids and then with mineral acid to remove basic substances. Refined naphthalene is obtained by subliming, or preferably by distilling the crude product.

Description and uses.

The Tariff Act of 1930 defines crude naphthalene as naphthalene solidifying under 79° C. after the removal of all water present; and refined naphthalene as that having a solidifying point at or above 79° C. after the removal of all water present.

Crude grades, melting between 70° and 78.5° C., are found in commerce as yellow, red, or brown crystalline solids. These grades are used in the manufacture of phthalic anhydride and other coal-tar intermediates; in the manufacture of lampblack; to enrich illuminating gas and sometimes motor fuel; in synthetic tanning materials; and in certain insecticides. Probably its most important outlets are as a raw material for phthalic anhydride (see p. 98) and refined naphthalene.

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Refined grades, melting above 79° C., are marketed as white, crystalline lumps or flakes. Their principal uses are in the manufacture of intermediates, dyes, medicinals, solvents, and textile assistants; as moth repellants; as a lubricant when mixed with rapeseed oil; to remove the “bloom” from lubricating oils; as a preservative for rubber goods and animal skins; and in explosives (trinitro naphthalene). In 1936 more than 75 coal-tar intermediates made from naphthalene were commercially produced in the United States. Of the 75 million pounds of these intermediates produced in that year, 31 million pounds were phthalic anhydride, an important component of synthetic resins of the alkyd type.

United States production.

Crude naphthalene is produced in the United States by byproduct coke-oven operators, gas works that produce their own coal tar, and also by firms that purchase coal tar and distill it. Statistics of production by groups are shown in table 33.

Table 33.—Crude naphthalene: United States production, 1918-37