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

POLYBASIC ACIDS OTHER THAN PHTHALIC ANHYDRIDE

Maleic acid and anhydride.

Maleic anhydride is obtained as a byproduct in the manufacture of phthalic anhydride and as a major product by the vapor phase catalytic oxidation of benzene. Domestic production, still small compared with phthalic anhydride, has increased many fold during the past two or three years. In 1937 there were three producers of maleic anhydride, with an output totaling 2,114,176 pounds. The uses of maleic acid derivatives other than in making resins are minor.

Malic acid and malomalic acid.

Malic acid is widely distributed in the vegetable kingdom, occurring especially in unripe apples. Commercially it is obtained by synthesis. Domestic production was reported for the first time in 1935. Malomalic acid is formed by heating malic acid. United States Patent No. 1,091,627 covers a resin made from malic acid and glycerin which will increase the toughness of phthalate resins. United States Patent No. 1,667,198 suggests the use of malomalic acid to form resins of glass-like appearance.

Adipic acid.

Adipic acid is made by oxidation of cyclohexanol. When condensed with glycerin it yields an alkyd resin which is soft and rubbery and which does not harden when heated. Numerous patents have been granted on the preparation of adipic acid and its resins. Commercial production of adipic acid was first reported in 1935, and the output increased in 1936 and in 1937.

Succinic acid and anhydride.

Succinic acid is a white crystalline powder melting at 185° C. and boiling at 234° C., with decomposition to succinic anhydride. It may be obtained by the reduction of maleic acid. Condensation with glycerin gives a resin tougher and more flexible than is obtained with phthalic anhydride.

In 1937 there were two commercial producers of succinic acid. It is believed that small quantities are used in combination with phthalic anhydride in alkyd resins.

Fumaric acid.

Fumaric acid is a white crystalline powder obtained by the prolonged heating of or by the action of mineral acids on maleic acid. Fumaric acid and maleic acid are structurally identical and the former decomposes at about 280° C., forming the latter. In 1937 there was one domestic maker of fumaric acid.