PROCESS FOR THE PRODUCTION OF STABILIZED POLYISOCYANATES, STABILIZED ISOCYANATES OF RETARDED REACTIVITY AND THEIR USE IN THE PRODUCTION OF POLYURETHANES

摘要

A PROCESS FOR THE PRODUCTION OF STABILIZED POLYISOCYANATES, STABILIZED ISOCYANATES OF RETARDED REACTIVITY AND THEIR USE IN THE PRODUCTION OF POLYURETHANES The present invention relates to a process for the production of solid polyisocyanates of retarded reactivity stabilized by surface modification by reacting solid, finely divided polyisocyanates, and particularly dimeric tolylene diisocyanate, dimeric diphenylmethane diisocyanate and 3,3'-diisocyanato-4,4'-dimethyl-N,N'-diphenyl urea, with acyclic, mono- or bicyclic compounds having an amidine or guanidine structure and which do not contain any hydrogen atoms reactive to isocyanates at room temperature in a quantity of from 0.1 to 25 equivalent percent of "amidine" or "guanidine" per isocyanate equivalent. The reaction may be carried out directly in a liquid medium selected from the group consisting of (i) organic compounds containing one or more hydroxy groups having molecular weights of from 62 to 6000, (ii) organic compounds containing two or more aromatically-bound amino groups and having molecular weights of from 108 to 6000, (iii) organic compounds containing two or more aliphatically-bound amino groups and having molecular weights of from 400 to 6000, (iv) plasticizers, (v) water, (vi) mixtures thereof, and (vii) mixtures of any one or more of (d)(i) through (d)(vi) with an apolar or slightly polar solvent, to form a suspension of polyadduct-coated, stabilized polyisocyanates in the liquid medium.