Patent ID: 8822595

Claim:
A method for making a polyisocyanurate comprising: forming an isocyanate-reactive mixture comprising: a trimerization catalyst comprising 1-12 carbon atoms; and the reaction product of an anhydride and a polyol; wherein the polyol has an average equivalent weight of 100-2500 and an average nominal hydroxyl functionality of 2-8; wherein the trimerization catalyst is selected from the group consisting of alkali metal carboxylates, which are selected from the group consisting of potassium acetate, potassium hexanoate, potassium ethylhexanoate, potassium octoate, and potassium lactate, quaternary ammonium carboxylates and mixtures thereof, wherein the molar amount of the anhydride ranges from 0.1 to 99% of the hydroxyl equivalent amount of the polyol, and wherein the ratio of the number of carboxylic acid groups to the number of ester groups, both formed in the reaction between the anhydride groups and the polyol, is 0.9-1.1 to 1 and wherein at least 60% of the anhydride groups has been converted; forming a polyisocyanate composition by adding the isocyanate-reactive mixture to a polyisocyanate compound at a temperature in the ranqe of 5° C. to 45° C.; and forming the polyisocyanurate by heating the polyisocyante composition to a temperature ranging from 50° C. to 350° C.