Abstract: 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, c) blowing agents, wherein b) comprise b1) from 70 to 10 parts by weight of at least one polyether alcohol having polyoxypropylene units, a nominal functionality of from 3 to 6 and a hydroxyl number of 100 to 300 mg KOH/g, b2) from 10 to 70 parts by weight of at least one polyetherol having polyoxypropylene units, a nominal functionality of 2 and a hydroxyl number of 50 to 350 mg KOH/g, b3) from 10 to 30 parts by weight of at least one polyether alcohol having ethylene oxide units, a nominal functionality of from 2 to 3 and a hydroxyl number of 50 to 550 mg KOH/g, b4) from 0 to 20 parts by weight of at least one graft polyetherol having a nominal functionality of from 2 to 3 and a hydroxyl number of 20 to 40 mg KOH/g.

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, c) blowing agents, wherein the compounds having at least two hydrogen atoms which are reactive toward isocyanate groups b) comprise b1) from 70 to 10 parts by weight of at least one polyether alcohol consisting of exclusively polyoxypropylene units or polyoxypropylene units and not more than 20% by weight, based on the total weight of the alkylene oxides used, of polyoxyethylene units in the polyether chain and having a nominal functionality of from 3 to 6 and a hydroxyl number in the range from 100 to 300 mg KOH/g, b2) from 10 to 70 parts by weight of at least one polyetherol consisting of exclusively polyoxypropylene units or polyoxypropylene units and not more than 20% by weight, based on the total amount of alkylene oxides used, of polyoxyethylene units in the polyether chain and having