Process for the production of polyurethane foams

In a process for the production of polyurethane foams comprising reacting a reaction mixture consisting essentially of

• a) a polyisocyanate component, with
• b) a polyol component free from salt groups, in the presence of
• c) at least one blowing agent, and
• d) salts of ester-functional .alpha.,.beta.-unsaturated carboxylic acids, the improvement comprising d) said salts of ester-functional .alpha.,.beta.-unsaturated carboxylic acids comprising the salt of the reaction products of
• (i) alcohols selected from the group consisting of monohydric ether-functional alcohols having a molecular weight in the range from 250 to 1000, and polyhydric, optionally ether-functional alcohols having a molecular weight in the range from 62 to 8000, and mixtures thereof;
• and
• (ii) .alpha.,.beta.-unsaturated dicarboxylic acids, or intramolecular anhydrides thereof;
• wherein said salts contain on a statistical average, at least one alkali metal carboxylate group and at most 0.5 alcoholic hydroxyl groups per molecule, and are present in a quantity of from 0.01 to 100% by weight, based on the weight of component b).