Method for producing viscoelastic polyurethane flexible foams

Abstract

The invention relates to a process for producing viscoelastic flexible polyurethane foams by reacting a) polyisocyanates with b) compounds having at least two hydrogen atoms which are reactive toward isocyanate groups, wherein a mixture of bi) from 25 to 70% by weight, based on the weight of the components bi), bii), biii) and biv), of a hydroxyl-comprising natural oil or fat or a reaction product of a hydroxyl-comprising natural oil or fat with alkylene oxides, bii) from 3 to 30% by weight, based on the weight of the components bi), bii), biii) and biv), of at least one polyether alcohol which has a hydroxyl number of from 100 to 800 mg KOH/g and a functionality of from 3 to 5 and is selected from the group consisting of polyether alcohols prepared by addition of alkylene oxides onto an amine, biii) 20-50% by weight, based on the weight of the components bi), bii), biii) and biv), of at least one polyether alcohol which has a hydroxyl number of from 10 to 80 mg KOH/g and a functionality of from 2 to 5 and can be prepared by addition of ethylene oxide and propylene oxide onto H-functional starter substances, where the proportion of ethylene oxide is 5-25% by weight, based on the weight of the polyether alcohol, and at least part of the ethylene oxide is added on at the end of the polyether chain, biv) >0-8% by weight, based on the weight of the components bi), bii), biii) and biv), of at least one polyether alcohol having a functionality of 2-4, a hydroxyl number of 15-60 mg KOH/g and a content of ethylene oxide of >50% by weight, based on the weight of the polyether alcohol, as compounds having at least two hydrogen atoms which are reactive toward isocyanate groups.

Dependencies are inferred from the claim text.