Process for the production of polyisocyanates containing allophanate and isocyanurate groups

Abstract

The present invention is directed to a process for the production of a polyisocyanate composition having an NCO content of 10 to 47% by weight and a viscosity of less than 2,500 mPa.s, wherein the viscosity is determined from a mixture containing less than 1% by weight of the starting organic diisocyanate, and containing isocyanurate and allophanate groups in a molar ratio of monoisocyanurates to monoallophanates of 10:1 to 1:5 by a) catalytically trimerizing a portion of the isocyanate groups of an organic diisocyanate having (cyclo)aliphatically bound isocyanate groups b) adding 0.01 to 0.5 moles, per mole of organic diisocyanate, of a monoalcohol containing 6 to 9 carbon atoms to the organic diisocyanate prior to or during the trimerization reaction of step a) and c) terminating the trimerization reaction at the desired degree of trimerization by adding a catalyst poison and/or by thermally deactivating the catalyst, wherein said trimerization catalyst is a compound containing aminosilyl groups or a catalyst which is capable of reducing the isocyanate content of a mixture consisting of 1,6-hexamethylene diisocyanate containing less than 10 ppm of carbon dioxide and the trimerization catalyst from 50% to 45% by weight or less within a period of 4 hours at a catalyst concentration of 500 ppm, based on the weight of 1,6-hexamethylene diisocyanate, and a temperature of 80.degree. C.

Dependencies are inferred from the claim text.