Manufacture of cellular polyurethanes

Cellular polyurethanes are prepare by reacting an organic polyisocyanate with a polyester made by reaction of a glycol with a dibasic carboxylic acid and an aromatic compound containing at least one aromatic nucleus and sufficient aliphatic hydroxyl groups and/or vicinal epoxide groups that said aromatic compound behaves in ester forming reactions as having more than two aliphatic hydroxyl groups, said polyurethane-forming reaction being carried out under such conditions that a foam-forming gas is generated. The aromatic compound may be the reaction product of epichlorhydrin or dichlorhydrin with a dihydric phenol and may have the formula where n is 0 or an integer and R and R1 are hydrogen or an alkyl group of 1-4 C. A surface active agent and tertiary amine catalyst may be present in the reaction mixture. Water or a halogenated alkane may be used as the foaming agent.