PROCESS FOR THE PREPARATION OF POLYISOCYANATES CONTAINING ISOCYANURATE GROUPS AND THEIR USE FOR THE PREPARATION OF POLYISOCYANATE POLYADDITION PRODUCTS

摘要

PROCESS FOR THE PREPARATION OF POLYISOCYANATES CONTAINING ISOCYANURATE GROUPS AND THEIR USE FOR THE PREPARATION OF POLYISOCYANATE POLYADDITION PRODUCTS The present invention is directed to a process for the preparation of isocyanurate group-containing polyisocyanates by trimerizing a portion of the isocyanate groups of an organic polyisocyanate and terminating the trimerization reaction by the addition of a catalyst poison, characterized in that the trimerization catalyst used is a quaternary phosphonium salt of a tertiary phosphine and an alkylating ester of an acid of phosphorus. The present invention also relates to the use of the polyisocyanates obtained according to this process, optionally, in a form that has been freed from excess starting polyisocyanate and/or optionally blocked with blocking agents for isocyanate groups as the isocyanate component for the preparation of polyisocyanate polyaddition products, preferably polyurethanes.