Patent ID: 6077456
Filing Date: 2000-06-20
Classification: C08G

Abstract:
A liquid polyisocyanate prepolymer comprising the reaction product of an organic polyisocyanate blend and a polyoxypropylene polyether polyol, said polyisocyanate blend comprisingA) a diphenylmethane diisocyanate component comprising from 50 weight percent to 98 weight percent 4,4'-diphenylmethane diisocyanate, from 2 weight percent to 50 weight percent 2,4'-diphenylmethane diisocyanate, and less than 10 weight percent 2,2'-diphenylmethane diisocyanate, said weight percentages based on the total weight of the ingredients in A);B) a polymethylene polyphenyl polyisocyanate component comprising from 30 weight percent to 70 weight percent diphenylmethane diisocyanate, the remainder comprising polymethylene polyphenyl polyisocyanates having functionalities greater than two, said weight percentages based on the total weight of the ingredients in B);C) and optionally a uretonimine-carbodiimide modified diisocyanate component comprising from 10 weight percent to 35 weight percent uretonimine-carbodiimide species, the remainder comprising essentially pure 4,4'-diphenylmethane diisocyanate, said weight percentages based on the weight of the ingredients in C);said polyoxypropylene polyether polyol having a number average molecular weight ranging from greater than 1500 to 10,000 and an average functionality from 1.6 to about 3, wherein the polyol is reacted with the polyisocyanate blend at temperatures less than 80.degree. C., the liquid polyisocyanate prepolymer having an overall NCO content of from 22 weight percent to 31 weight percent.