FORMATION OF BLOCKED, ISOCYANURATE GROUP-CONTAINING POLYISOCYANATES FROM PARTIALLY BLOCKED ISOCYANATES

摘要

The present invention relates to a process for the preparation of blocked polyisocyanates containing isocyanurate groups by a) reacting 20 to 80 equiv.% of the isocyanate groups of an organic diisocyanate with a pyrazole or triazole blocking agent, b) trimerizing the remaining unblocked isocyanate groups in the presence of a basic trimerization catalyst until the isocyanate content is less than 2.5% by weight, based on the weight of the blocked polyisocyanate and c) optionally blocking any remaining isocyanate groups with a blocking agent for isocyanate groups. The present invention also relates to the use of these blocked polyisocyanates for the production of polyisocyanate addition products.