Abstract: A process for producing high resilience polyurethane foam utilizing as a foam stabilizer a combination of an organosilicone oil of average molecular weight 200-2000 composed of the blocks represented by the formula ##EQU1## (where a+b is 1 to 3, b is 0 or 1, R is methyl group, and R' is a hydrocarbon group of 3-15 carbon atoms) and a hydrocarbon oil of average molecular weight 200-2000 containing more than 20 wt. % of alicyclic hydrocarbon and/or aromatic hydrocarbon.

Abstract: A process for manufacturing high-resilient flexible urethan foams characterized by, reacting and foaming polyalkylene ether polyol and an organic polyisocyanate in the presence of a blowing agent, a surfactant and catalyst, (1) using as said polyalkylene ether polyol one which contains 2 to 10% by weight of a vinyl type polymer and in which its hydroxyl number ranges from 25 to 60 mg KOH/g, of its hydroxyl groups 20 to 70 mol% are primary hydroxyl groups and the remaining hydroxyl groups are secondary hydroxyl groups; (2) using as said organic polyisocyanate a mixture of tolylene diisocyanate with diphenylmethane diisocyanate or a crude diphenylmethane diisocyanate; and (3) using as said surfactant a mixture of a high-molecular-weight siloxane-oxyalkylene copolymer with a low-molecular-weight siloxane-oxyalkylene copolymer.