Process of preparing foams with internal mold-release agents

Claim 1

In a process for the production of molded articles of polyurethane foam by foaming a reaction mixture in a closed mold, said reaction mixture comprising a polyisocyanate, an organic compound containing at least two hydrogen atoms reactive with isocyanates, and a blowing agent, the improvement wherein said polyisocyanate consists of the reaction product of (a) an organic polyisocyanate, and (b) from 0.5 to 25% by weight based on the quantity of said organic polyisocyanate, of an active hydrogen-containing fatty acid ester prepared by reacting an alcohol with an aliphatic, saturated or unsaturated fatty acid, said ester being characterized in that at least one aliphatic acid which contains more than 8 carbon atoms is built into the molecule, said ester further characterized as having an acid number of 0 to 100 and a hydroxyl number of 0 to 150 with at least one of said numbers being greater than 0 and said ester having an average molecular weight of from 500 to 5000.