PLASTICS KLINE 235 



Lignin plastics. — The utilization of waste wood and sawdust for 

 the production of molding compositions has been the objective of a 

 considerable number of investigators for the past 10 years. Wood 

 contains approximately 25 percent of lignin, a complex and highly 

 reactive organic compound. In 1937 a lignin plastic first became 

 available under the trade name Benaloid, manufactured by the Ma- 

 sonite Corporation. The development of lignin molding compo- 

 sitions of both the thermoplastic and thermosetting types was 

 announced in 1939 by the Marathon Chemical Co. The possible 

 commercial applications of this tj^pe of plastic have just begun to 

 be explored. The low cost of the necessary ingredients makes this 

 plastic of interest for industrial applications which require large 

 quantities of material, such as certain automotive parts, building 

 units, furniture, and wall paneling. 



Alkyd resins. — A survey of plastics would not be complete without 

 mention of the alkyd resins. They are used primarily as coating 

 materials which, incidentally, are the largest single outlet for syn- 

 thetic resins. Over 75,000,000 pounds of these resins were produced 

 in 1939, out of a total resin production of about 215,000,000 pounds 

 for that year. They are made by the reaction of phthalic anhydride 

 or maleic anhydride with glycerol or other polyhydric alcohols. 



Finishes based on these resins, Glyptal, Dulux, and Rezyl, are 

 characterized by rapidity of drying, good durability outdoors, excel- 

 lent flexibility, tenacious adhesion, and electrical insulating qualities. 

 These resins during the thirties replaced the pyroxylin lacquers to a 

 large extent for finishing the bodies and fenders of motor cars. 



Nylon resins. — These polyamide resins are made from polyamines 

 and polybasic acids. They could be called amkyd resins, following 

 the terminology used in the name "alkyd" for resins made from 

 polyhydric alcohols and polybasic acids. The basic raw materials 

 for nylon resins are castor oil from which sebacic acid (a 10-carbon 

 dibasic acid) is obtained, and phenol which by hydrogenation and 

 oxidation yields adipic acid (a 6-carbon dibasic acid) . Hexamethyl- 

 ene diamine made from adipic acid, and decamethylene diamine made 

 from sebacic acid are typical diamines used in synthesizing these 

 resins. Nylon resin was made available on a large scale by E. I. 

 du Pont de Nemours and Company, Inc., during 1940. It has already 

 proved its suitability to manufacturer and consumer alike for hosiery 

 and has been accepted as a superior bristle material for tooth brushes, 

 hair brushes, and brushes for miscellaneous industrial purposes. 



C oumarone-indene resins. — The manufacture of this type of resin 

 from certain coal-tar distillates was begun in 1919 by the Barrett 

 Co. using the trade name Cumar. In 1929 the Neville Co. marketed 

 such resins as Nevindene. The low softening points and brittleness 

 of these resins have restricted their use to serving as plasticizing 



