Polyurethane foams with reduced aromatic amine content

A process for producing polyurethane foams having a density of 30 g/dm3 to 70 g/dm3, the process comprising mixing

• a) aromatic polyisocyanate,
• b) polymeric compounds having isocyanate-reactive groups,
• c) optionally chain extender and/or crosslinking agent,
• d) catalysts,
• e) blowing agent comprising water,
• f) lactam in an amount of 0.1% to 5% by weight, based on the total weight of components a) to f), and
• g) optionally additives,
• at an isocyanate index of 50 to 95 to form a reaction mixture, and
• converting the reaction mixture to a flexible polyurethane foam,
• wherein the catalysts comprise a metal catalyst and an amine catalyst, and the amine catalyst has tertiary nitrogen atoms and is used in such an amount that a content of tertiary nitrogen atoms in the amine catalyst is from 0.0001 to 0.002 mol/100 g of foam;
• wherein the amine catalyst has at least one isocyanate-reactive group;
• wherein the catalysts d) are used in amounts such that the reaction mixture has a gel or fiber time in a range of from 60 to 180 seconds;
• wherein the reaction mixture is converted to the flexible polyurethane foam in a closed mold.