Process for the preparation of urethane oils

Urethane oils are prepared by reacting hydroxyl group-containing esters of ethylenically unsaturated fatty acids and polyhydric alcohols or ester interchange products of drying and/or semi-drying vegetable oils or fatty acid triglycerides and polyhydric alcohols, hydroxycarboxylic acids or aminoalcohols with polyisocyanates, which polyisocyanates have an isocyanurate structure. Preferred polyisocyanates are those having the formula wherein the radicals R are the same or different divalent hydrocarbon radicals, which may be substituted or contain hetero atoms or the group and especially those of isocyanurate structure derived from benzene 1-alkyl-2,4-diisocyanates. The hydroxyl-group containing esters are suitably derived from such oils as linseed, perilla, wood, oiticica, ricinene, cottonseed, safflower, sunflower, hemp, tall, soyabean, walnut, sesame rape or poppy seed by ester interchange with polyhydric alcohols, hydroxycarboxylic acids and/or amino alcohols. Polar solvents may be used for the reaction of the polyisocyanates with the hydroxyl containing esters and these may be replaced with non-polar solvents as soon as partial urethane formation has taken place. Short chained diols such as butane or hexane diols and long chained diols such as polyethylene glycol ethers may be mixed with the hydroxyl group containing esters prior to reaction with the polyisocyanates.