PROCESS FOR PREPARING CELLULAR POLYURETHANE ELASTOMERS AND PREPOLYMERS SUITABLE FOR THIS PURPOSE

摘要

1. A process for preparing polyurethane elastomers by reacting polyhydroxyl compounds having a functionality of from 2 to 3 and a molecular weight of from 800 to 6000 with aromatic diisocyanate with resulting intermediate product to be reacted with organic polyisocyanates to form a prepolymer, which is reacting with water by chain extenders and/or crosslinkers having a molecular weight of up to 800 in the presence or absence of catalyst, characterized in that the reaction of polyhydroxyl compounds with aromatic diisocyanate selected from the group consisting of diphenylmethane diisocyanate and its mixture with 1,4-phenyl diisocyanate, is made in an equivalence ratio of hydroxyl groups to isocyanate groups of 1 : > 1 - 6, and a reaction of the intermediate product containing urethane and isocyanate groups, with organic polyisocyanate, which is 1,4-phenyl diisocyanate is made in an equivalence ratio of hydroxyl groups of one mother polyhydroxyl compounds to isocyanate groups of 1 : 0.02-6. 2. A process as claimed in claim 1, wherein the polyhydroxyl compounds are difunctional polyhydroxyl compounds with a molecular weight of from 800 to 3,500 and are selected from the group consisting of polyester polyols, hydroxyl-containing polycarbonates and polyoxybutylene glycols. 3. Prepolymers containing isocyanate groups, having an NCO content of from 3.3 to 10 % by weight and prepared by reacting at least one polyhydroxyl compound having a functionality of from 2 to 3 and a molecular weight of from 800 to 6000 with diphenylmethane diisocyanate in an equivalence ratio of hydroxyl groups to isocyanate groups of 1: > 1 - 6, and a reaction of the intermediate product containing urethane and isocyanate groups and having an NCO content of from 0.05 to 8 % by weight with 1,4-phenyl diisocyanate in an equivalence ratio of hydroxyl groups to isocyanate groups to isocyanate groups of at least one mother polyhydroxyl compounds to isocyanate groups of 1 : 0.02-6. 4. Prepolymers containing isocyanate groups, having an NCO content of from 3.3 to 10 % by weight and prepared by reacting at least one polyhydroxyl compound having a molecular weight of from 800 to 3500 selected from group comprising polyester polyols, hydroxyl-containing polycarbonates and polyoxytetramethylene glycols with 4,4'-diphenylmethane diisocyanate in an equivalence ratio of hydroxyl groups to isocyanate groups of 1: > 1 - 6, and a reaction of the intermediate product containing urethane and isocyanate groups and having an NCO content of from 0.05 to 8 % by weight with 1,4-phenyl diisocyanate in an equivalence ratio of hydroxyl groups to isocyanate groups to isocyanate groups of at least one mother polyhydroxyl compounds to isocyanate groups of 1 : 0.02-6.