Viscoelastic elastomeric polyurethane foams, process for preparing them and use thereof

A viscoelastic elastomeric polyurethane foam obtained by reacting a reactive mixture comprising:

• (A) an isocyanate component comprising at least one isocyanate prepolymer (A1), wherein the isocyanate component has an NCO content in between 10 wt. % to 30 wt. %, and
• (B) an isocyanate reactive component comprising a mixture of
• (a) 60 wt. % to 95 wt. % of at least one natural oil polyol having an average functionality in between 2.0 to 4.0 and OH value in between 30 mg KOH/g to 600 mg KOH/g, determined according to DIN 53240,
• (b) 0.1 wt. % to 10.0 wt. % of at least one first polyether polyol having an average functionality in between 2.5 to 5.0 and OH value in between 200 mg KOH/g to 450 mg KOH/g, determined according to DIN 53240, which is prepared by addition of at least one alkylene oxide onto an amine,
• (c) 1.0 wt. % to 30.0 wt. % of at least one second polyether polyol having an average functionality in between 2.0 to 4.0 and OH value in between 20 mg KOH/g to 200 mg KOH/g, determined according to DIN 53240, which is prepared by addition of ethylene oxide and propylene oxide onto at least one H-functional starter substance, wherein the proportion of ethylene oxide is in between 40 wt. % to 95 wt. % based on the weight of the at least one second polyether polyol, and
• (d) 0 wt. % to 10.0 wt. % of at least one chain extender and/or crosslinker having a molecular weight in between 40 g/mol to 499 g/mol, wherein wt. % of the at least one natural oil polyol, the at least one first polyether polyol, the at least one second polyether polyol, and the at least one chain extender and/or crosslinker are based on the sum of (a), (b), (c) and (d), in the presence of
• (C) a blowing agent mixture comprising water (C1) and at least one hydrofluorocarbon (C2), or water (C1) and at least one hydrofluoroolefin (C3).