Patent ID: 6992186

Claim:
Process for preparing solvent-containing polyisocyanates based, at least in part, on 2,4- and/or 2,6-diisocyanatotoluene which contain isocyanurate groups comprising a) reacting, at a temperature from 20° C. to 120° C., a mixture of A) from 20 to 80% by weight, based on the mixture, of a diisocyanate component containing at least 80% by weight, based on all diisocyanates, of 2,4- and/or 2,6-diisocyanatotoluene, B) from 20 to 80% by weight, based on the mixture, of solvent and C) 0–20% by weight, based on the mixture, of an alcohol component, and also D) phenolic catalysts containing dialkylaminomethyl groups; b) metering in, in one or more steps, in the course of ongoing trimerization additionally 0.1–25% by weight, based on the amount of diisocyanates employed, of monomeric 2,4-diisocyanatotoluene, wherein at least a portion of the 2,4-diisocyanatotoluene is added after the NCO content in the mixture of a) as been reduced due to the reaction of A); and c) ending the reaction by adding catalyst poisons; wherein the reacted mixture contains <0.1% by weight, based on the mixture, of monomeric diisocyanate.