Synthetic resin

“ 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. ”

“ 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 ”

“ Synthetic resin.—A complex, substantially amorphous, organic semisolid or solid material (usually a mixture of substances) built up by chemical reaction of comparatively simple compounds and, depending upon the temperature at which the examination is made, approximating the natural resins in various physical properties: namely, luster, fracture, comparative brittleness, insolubility in water, fusibility or plasticity when heated or exposed to heat and pressure, and, at a certain more or less narrow temperature range before fusion, showing a degree of rubberlike extensibility ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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 ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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 ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”