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 references to factors essential to tariff consideration. Under the general provisions of section 332, title III, part II, Tariff act of 1930.

by United States Tariff Commission

3. TAR-ACID RESINS

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 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.