MANUFACTURE OF POLYISOCYANATE PLASTIC

The present invention is directed to a process for the production of plastics based on an isocyanate-polyaddition product by (1) forming an isocyanate group-containing prepolymer from (a) a compound which has a molecular weight of from 146 to about 10,000, is substantially free from hydroxyl groups, contains at least two terminal carboxyl groups and optionally contains ether and/or ester groups, (b) excess quantities of an organic nonaromatic polyisocyanate which has at least one cyclohexane ring and exclusively contains aliphatically- and/or cycloaliphatically-bound isocyanate groups and (c) up to 10 equivalent percent, based on the isocyanate-reactive groups in component (a), of a compound which is monofunctional for the purposes of the isocyanate-addition reaction and, (2) reacting the product of step (1) with (d) a chain-lengthening agent such as water, a polyamine containing at least two primary and/or secondary amino groups or hydrazine or a derivative thereof containing at least two primary and/or secondary amino groups.