PROCESS FOR THE PREPARATION OF POLYISOCYANATES WITH BIURET STRUCTURE

摘要

PROCESS FOR THE PREPARATION OF POLYISOCYANATES WITH BIURET STRUCTURE The present invention relates to a process for the preparation of polyisocyanates which have a biuret structure by reacting excess quantities of aliphatic diisocyanates with biuretizing agents at elevated temperature, characterized in that the biuretizing agent contains a) .alpha.,.alpha.,.alpha.-trisubstituted acetic acids which do not contain isocyanate-reactive groups apart from the carboxyl group, and optionally b) water, wherein the molar ratio of biuretizing components a) to b) is within the range of from 1:0 to 1:2.5.