Polyurethan

1,200,845. Polyurethane compositions. DOW CHEMICAL CO. 8 March, 1968, No. 11489/68. Heading C3R. A polyurethane composition comprises the reaction product in the presence of an initiating catalyst of a polyisocyanate, a polyol and a plasticizer, the polyol being the reaction product of a polyhydric alcohol containing 3 to 8 hydroxyl groups and propylene oxide in amount corresponding to 1 to 1À33 moles of propylene oxide per hydroxyl group in the alcohol, and the plasticizer being an ester of a 2 to 20 carbon atom dicarboxylic acid or anhydride thereof and an aliphatic alcohol having 7 to 20 carbon atoms, the polyol being used in an amount corresponding to 40 to 60% and the plasticizer 60 to 40%, by weight based on the sum of the weights of polyol and plasticizer and the polyisocyanate being used in amount to provide 0À85 to 1À15 NCO equivalents for each OH group of the polyol. The catalyst may be an organo tin compound or a tertiary amine. The polyol, plasticizer and catalyst are preferably mixed together and to the mixture is added the polyisocyanate. In examples, tris-(hydloxypropyl) glycerine is used as the polyol, tolylene diisocyanate as the polyisocyanate, stannous octoate as the catalyst and the plasticizer may be dioctyl phthalate, di(2-ethylhexyl) phthalate, di(2-ethylhexyl) adipate, dioctyl sebacate, dioctyl azealate or diheptylphthalate.