Low density polyurethane microcellular elastomer

The present invention is concerned with a process for producing polyurethane foam moldings having a density of200 to 500 g/dm3, wherein (a) polyisocyanate prepolymer obtainable by reacting at least one organic polyisocyanate (al), at least one first polyesterol (a2) and at least one polyetherol (a3) obtained from the alkoylation of a starter molecule with alkylenoxide compris­ ing ethylene oxide wherein the polyetherol (a3) has a hydroxyl number in the range of20 to 65 mg KOH/g, a number average mo­ lecular weight of 2000 to 6000, a functionality of I.7 to 3.0 and a content of ethylenoxide units in the range of 13 to 30 % by weight based on the total weight of the polyetherol (a3) and wherein the content of the polyetherol (a3), based on the total weight of the or­ ganic polyisocyanate prepolymer (a), is in the range of 3 to 15 % by weight, is mixed with (b) at least one second polyesterol, (c) blowing agent and optionally (d) chain extender and/or crosslinker, (e) catalyst and (f) other auxiliaries and/or additives to form a re­ action mixture, the latter is introduced into a mold and allowed to react to form a polyurethane foam molding. The present invention further concerns a polyurethane foam moldings obtained from a process according to the invention and the use of a polyurethane foam moldings according to the invention as shoe sole.