Patent ID: 6765111
Filing Date: 2004-07-20
Classification: C07D,C08G

Abstract:
A process for the preparation of a polyisocyanate containing isocyanurate groups which comprisesa) trimerizing a portion of the isocyanate groups of hexamethylene diisocyanate, which contains less than 10 ppm by weight of carbon dioxide, in the presence of a positive amount of less than 0.03% by weight, based on the weight of hexamethylene diisocyanate, of a quaternary ammonium hydroxide catalyst corresponding to the formula â€ƒwherein R1, R2 and R3 may be the same or different and represent alkyl radicals containing 1 to 18 carbon atoms and R4 is a benzyl radical, b) terminating the trimerization reaction at the desired degree of trimerization by the addition of a catalyst poison and/or by thermal deactivation and c) subsequently removing unreacted hexamethylene diisocyanate such that said polyisocyanate contains at most 0.2% by weight of hexamethylene diisocyanate, based on the weight of said polyisocyanate.