Patent ID: 6084051
Filing Date: 2000-07-04
Classification: C08G,C09D

Abstract:
An aqueous polyurethane-urea dispersion having a resin solids content of at least 35 wt. % and a pH of at least 7.5 which is prepared bya) forming an isocyanate-terminated prepolymer by reactingA) a difunctional polyol having a number average molecular weight of 500 to 6000,B) an at least difunctional low molecular weight alcohol having a number average molecular weight of less than 500,C) a diisocyanate and/or triisocyanate, andD) a compound which has an acid group and one or two isocyanate-reactive groups comprising a member selected from the group consisting of hydroxy, primary amino and secondary amino groups, and which is present in an amount sufficient to provide an acid number, based on resin solids, of 12 to 27 mg of KOH/g,b) neutralizing 65% to 95% of the acid groups of component D) prior to dispersing the prepolymer in water,c) dispersing the neutralized prepolymer in water,d) chain extending the isocyanate groups with water to form a polyurethane-urea, ande) after completion of the chain extending reaction adding additional neutralizing agent to provide a total amount of neutralizing agent that is sufficient to neutralize at least 115% of the acid groups of component D),wherein the polyurethane-urea contains 1.0 to 4.0%, based on resin solids, of the isolated urea groups shown in square brackets in formula (I) ##STR4##