I 



PLASTICS — KLINE 233 



dustry has resulted from their efficiency in providing a diffused light, 

 plus their lightness in weight and shock resistance. The fact that 

 they are insoluble, infusible, tasteless, and generally chemically inert 

 has made possible their successful use for bottle closures and light- 

 weight tableware. The urea-formaldehyde resins have also been in- 

 troduced into the field of laminated plastics as paneling and trim for 

 bathrooms, libraries, and hotel and theater lobbies, in order to take 

 advantage of the many stable colors in which they are produced. 



Cast phenolic plastics. — Phenolic resin for casting is prepared in 

 the form of a viscous syrup which is poured into lead or rubber molds 

 and hardened by heating. Products were made as early as 1910 from 

 cast Bakelite resinoids, but in their modern form cast phenolics were 

 first introduced in America in 1928. Cast phenolics are known by 

 such trade names as Catalin, Gemstone, and Marblette. They owe 

 their popularity quite largely to their beauty and decorative value, 

 and this type of plastic is often referred to as the "gem of modern 

 industry." Typical application include advertising igns and dis- 

 play, clock cases, game counters and pieces, radio housings, and 

 lighting fixtures. More recently their ue in indutrial adhesives and 

 laminating varnishes has been promoted. 



Vinyl resin plastics. — Resins formed by copolymerization of vinyl 

 chloride and vinyl acetate were first made in the United States by 

 the Carbide and Carbon Chemicals Corporation under the trade name 

 Vinylite in 1928. This type of resin has found its most important 

 uses in phonograph records, coatings for concrete and metals, can 

 linings, adhesives, and electrical insulation. In a highly plasticized 

 form, it is now employed for making transparent belts, suspenders, 

 and shoe uppers. The resins formed from the individual esters — 

 vinyl chloride and vinyl acetate — are also important commercially 

 for the manufacture of wire and cable coverings, coated fabrics, ad- 

 hesives, and plastic wood-filled compositions. Polyvinyl butyral plas- 

 tic has been found to be outstandingly superior for use as the binder 

 in laminated glass for the automotive and aircraft industries. Three 

 plants were built for its manufacture during 1937 and 1938, and it 

 has now largely supplanted cellulose acetate in this particular appli- 

 cation. Production of vinylidene chloride resin was initiated by the 

 Dow Chemical Co. in 1939, and 1940 saw its successful use in fishing 

 lines and seat coverings. 



Styrene resin. — In 1937 the Dow Chemical Company made avail- 

 able a synthetic monomeric styrene of high purity and a correspond- 

 ing polymeric product, Styron, in clear, transparent form. The 

 Bakelite Corporation also started to manufacture Bakelite poly- 

 styrene this same year. The most significant properties of polysty- 

 rene are its low power factor and practically zero water absorption. 



