GB656994A - Interpolymers of drying oils, monoalkenyl-aromatic hydrocarbons and divinylbenzene - Google Patents

Abstract

Varnish resins are prepared by heating in the substantial absence of solvents, (a) a drying oil having less than 35 per cent of its olefinic linkages conjugated, (b) a polymerizable monoalkenyl aromatic hydrocarbon material comprising mainly styrene, and (c) divinylbenzene, the divinylbenzene and monoalkenyl material amounting to between 0.5 and 5 per cent and between 30 and 60 per cent, respectively, of the weight of polymerizable components. With the styrene may be used smaller amounts of a -methyl styrene, ar-vinyl toluene and ar-ethyl vinyl benzene. Suitable drying oils are linseed, soyabean, sardine and dehydrated castor oils or mixtures thereof, or mixtures of one or more of these with an oil of high conjugation, e.g. tung oil or oiticia oil, provided the average degree of conjugation is below 35. Solvents are preferably completely absent, but minor amounts, e.g. up to 10 per cent of the starting materials of a solvent such as benzene, toluene, xylene and ethyl benzene, may be present. Polymerization is preferably effected at 100-200 DEG C. in a closed vessel or in an inert atmosphere, in the presence of a peroxy catalyst, until at least 80 per cent of the alkenyl aromatic compounds are polymerized. The products are clear resins, soluble in or compatible with unbodied linseed oil and soluble in, for example, the above-mentioned solvents and mixtures of aromatic solvents with mineral spirits. Other additions, e.g. resins (including rosin), drying oils, driers, dyes and pigments, may be added. The varnish films may be hardened rapidly (1-10 hours) by heating at 120 DEG C. and are tack-free at temperatures of 150 DEG F. or higher.