Silicone-free foam stabilizers for producing polyurethane foams

A process for producing a polyurethane foam comprising mixing

• (a) polyisocyanate,
• (b) polymeric compounds having isocyanate-reactive groups,
• (c) silicone-free stabilizer,
• (d) optionally chain extending and/or crosslinking agents,
• (e) catalysts,
• (f) blowing agents, and
• (g) optionally auxiliaries and additives,
• to afford a reaction mixture and reacting the reaction mixture to afford the polyurethane foam,
• wherein the silicone-free stabilizer (c) is obtained by alkoxylation of a 2- to 8-functional starter molecule with alkylene oxides,
• wherein 0% to 9% by weight of the employed alkylene oxides is ethylene oxide, 0% to 50% by weight of the employed alkylene oxides is 1,2-propylene oxide and at least 50% by weight of the employed alkylene oxides comprise at least 4 carbon atoms and the number-average molecular weight of the silicone-free stabilizer (c) is 500 to 20 000 g/mol,
• wherein the proportion of the silicone-free foam stabilizer (c), based on the total weight of the compounds (b), (c), (d), (e), and (f), is 0.01% to 0.5% by weight, and
• wherein the content of silicone-based foam stabilizer is less than 0.3% by weight based on the total weight of the compounds (b), (c), (d), (e), and (f).