JPS6317087B

The instant invention is directed to a process for the production of polyurethane urea elastomers having a gross density of more than 200 kg/m3 comprising: casting a reaction mixture of (A) an isocyanate prepolymer produced from (a) 1 mole of a compound containing at least 2 Zerewitinoff-active hydrogen atoms and having a molecular weight of from 400 to 10,000 and (b) 2 to 10 moles of diisocyanatodiphenylmethane, (B) an aromatic diamine, and (C) 0 to 50 mole percent, based on component (B), of a polyol containing primary hydroxyl groups and having a molecular weight of from 62 to 6000, the equivalent ratio between component (A) and components (B) + (C) amounting to between 0.9:1 and 1.3:1, into a mold, hardening the reaction mixture in the mold and subsequently removing it from the mold, the improvement wherein said isocyanate prepolymer (A) has been produced using an isomer mixture comprising: from 15 to 80 mole percent of 2,4'-diisocyanatodiphenylmethane, from 20 to 85 mole percent of 4,4'-diisocyanatodiphenylmethane, and from 0 to 20 mole percent of 2,2'-diisocyanatodiphenylmethane.