Catalyst and process for preparing low-viscosity and color-reduced polyisocyanates containing isocyanurate groups

Abstract

A low-viscosity polyisocyanates and polyisocyanates of reduced color containing isocyanurate groups is prepared by a process comprising, partially trimerizing aliphatic and/or cycloaliphatic diisocyanates in the presence of 0.02 to 2% by weight, based on the weight of the diisocyanate starting material, of at least one trimerization catalyst of formula (I) 1 and wherein substituents A, B, C, and E simultaneousiy or independently of one another are hydrogen, chloro, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-alkoxycarbonyl, hydroxyl, (R5)3 SiO—, (R5)2 N—, —COOH, (R5)2N—CH2— or phenyl, it being 5 possible for any two adjacent radicals selected from the group A, B, C, D and B to form a conjoint 5- or 6-membered saturated or unsaturated ring which may also include nitrogen, sulfur or oxygen heteroatoms; F is hydrogen, methyl or fluoro; G is hydrogen, methyl or fluoro; R2 and R3 simultaneously or independently of one another are C1—C8-alkyl or R1; R4 is hydrogen, methyl, C2-C18-alkyl, C3-C8-cycloalkyl or C2-C12-alkoxy; R5 is C1-C18-alkyl; Y−is R6COO−; R6 is hydrogen or a branched or unbranched aliphatic or araliphatic C1-C12-alkyl radical, and then removing excess diisocyanate from the reaction medium.

Dependencies are inferred from the claim text.