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

7. COUMARONE AND INDENE RESINS

Coumarone and indene are present in appreciable quantities in certain coal-tar fractions, especially in the solvent naphtha fractions distilling between 160° and 190° C. No attempt is made to isolate them from the solvent naphtha. Such a procedure would be difficult and expensive and, since polymerization readily takes place in dilute solutions, it is more economical to use fractions of solvent naphtha rich in these substances. 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. Several byproducts, such as naphtha, paracoumarone soap, and high boiling oils, are also obtained.