PLASTICS — KLINE 231 



mold and cured in electrically heated ovens to drive off the volatile 

 constituents, oxidize or polymerize the oils or resins, and so trans- 

 form the plastic into a hard, infusible state. The cold-molding 

 operation is faster than hot-compression molding since the curing 

 is not done in the mold, but the higher pressures required for cold 

 molding and greater abrasive action of the mineral filler make mold 

 maintenance much more of a problem than it is in hot molding. 

 Typical applications of cold-molded plastics include connector plugs 

 on household electrical equipment, heat-resistant handles and knobs 

 for cooking utensils, and battery boxes. 



Phenol-formaldehyde resin. — The first and still the most versatile 

 of the commercial synthetic resins, the phenol-formaldehyde con- 

 densation product, was described and patented in 1909 by Leo Hendrik 

 Baekeland, Thus, both the original thermoplastic material, cellulose 

 nitrate plastic, and the original thermosetting material, phenol- 

 formaldehyde resin, were first developed commercially in America. 

 Johann Friedrich Baeyer had reported in 1872 that the reaction be- 

 tween phenols and aldehydes leads to the formation of resins, but 

 no products of industrial interest were obtained for the next 35 years 

 because of the inability of investigators to control the reaction. 

 Baekeland's fifth-mol patent provided this essential feature, and his 

 heat and pressure patent described the technique for converting this 

 resin in a relatively short time into a molded article of excellent 

 mechanical and electrical properties. The basic patents covering the 

 preparation of solutions of this resin and their use in impregnating 

 fibrous sheets to make laminated products were issued to Baekeland 

 in 1910 and 1912, respectively. 



The manufacture of Bakelite phenolic plastics was begun in Baeke- 

 land's Yonkers, N. Y., laboratory in 1907. The General Bakelite 

 Co. was organized in 1910 and was merged in 1922 with the Condensite 

 Co. and the Redmanol Chemical Products Co. into the Bakelite Cor- 

 poration. Since the expiration of the basic patent in 1926, many 

 other firms have marketed phenolic resins under other trade names, 

 for example, Durez and Resinox. 



An important modification of this general type of resin is the use 

 of furfural, produced from waste oat hulls, in place of formaldehyde 

 for the condensation reaction with phenol. 



Typical applications of phenolic plastics include distributor heads, 

 coil parts, switches, and related elements in automobiles and air- 

 planes, camera cases and other housings, corrosion-resistant apparatus, 

 and telephone and radio equipment. In combination with paper and 

 fabrics, phenolic resin produces laminated products which are used 

 for gears, bearings, trays, table tops, refrigerator doors, wall coverings, 

 doors, and counter and cabinet paneling. 



