Abstract: The invention relates to “low-density” polyurethane foams, preferably “low-density” flexible integral polyurethane foams, i.e. polyurethane foams with density of from 120 grams per liter (herein after termed g/L) to less than 300 g/L, obtainable via reaction of polyisocyanates (a) with a polyol component (b) comprising the following constituents: polyesterol (b-1) and polymer polyesterol (b-2), where the proportion of polymer polyesterols (b-2) is from more than 5 to less than 50% by weight, based on the total weight of component (b), and, if appropriate, chain extenders (c), in the presence of water (d) as blowing agent, and also to their use in shoe soles.

Abstract: In a process for preparing polyisocyanate polyaddition products by reacting isocyanates with compounds which are reactive toward isocyanates, in the presence or absence of blowing agents, catalysts, auxiliaries and/or additives, the reaction is carried out in the presence of (i) particles which have a size of <200 &mgr;m and a melting point in a range from 50 to 300° C., or in the presence of thermoset particles (ii) or in the presence of particles (i) and (ii).

Abstract: In a process for preparing polyisocyanate polyaddition products by reacting isocyanates with compounds which are reactive toward isocyanates, in the presence or absence of blowing agents, catalysts, auxiliaries and/or additives, the reaction is carried out in the presence of (i) particles which have a size of <200 &mgr;m and a melting point in a range from 50 to 300° C., or in the presence of thermoset particles (ii) or in the presence of particles (i) and (ii).