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

Description and uses.

Coumarone and indene resins are produced and marketed in the United States under the trade names Cumar and Neville. A number of grades are available, including the following:

Designation:	Melting point
Rubber grade, soft	50°-65° C.
Medium soft	65°-85° C.
Rubber grade, hard	85°-100° C.
Medium hard	100°-135° C.
Varnish grade	135°-160° C.

In addition to these, certain types are produced for special purposes.

The coumarone and indene resins are used to a large extent in varnishes for metal and wood. In this application they may be used to replace all or part of the higher priced natural resins and, to some extent, ester gum. Their application is somewhat limited by their rather short durability and elasticity. They are neutral, nonoxidizing and nonsaponifiable and impart to varnishes greater inertness and adhesion, fair dielectric strength, and shorter drying time than many of the natural resins. They cannot be used in nitrocellulose lacquer since they are not compatible with that plastic.

Another important use of these resins is as an ingredient in mastic floor tile, in the production of which a thermoplastic binder is used. Originally, asphalt was used, but demand for light colored tile necessitated some other binder, the requirements for which were met by the coumarone and indene resins.

The next largest application of these resins is in rubber compounding, their effect being to soften the rubber during milling and to facilitate its handling on rolls. They do not affect the aging qualities of rubber and are used as a softener for reclaimed as well as for new rubber.

Coumarone and indene resins are used, to some extent, in linoleum, for impregnating roofing felt, in electrical and friction tapes, paper and cloth sizing, printing inks, brake linings, adhesives, artificial leather, oil cloth, and shoe polishes. As a substitute for chicle as much as 10 percent may be incorporated in the chewing gum mixture. Their application in molded articles is very limited because of their brittleness and low tensile strength.