Process for producing allophanate group-containing polyisocyanates, urethane prepolymers, and polyurethane resin compositions

摘要

Polyurethane resin compositions include a urethane prepolymer with an active hydrogen group and a polyisocyanate, or a urethane prepolymer with an isocyanate group and an active hydrogen compound. The urethane prepolymers having an active hydrogen group or an isocyanate group are obtained by reacting an allophanate group-containing polyisocyanate with a side-chain hydrocarbon group of 5 or more carbon atoms and a bifunctional or polyfunctional active hydrogen compound. Particularly preferably, the allophanate group-containing polyisocyanate is obtained by reacting a C5 or higher carbon_number compound having an alcoholic hydroxyl group and an organic diisocyanate, in the presence of an organic bismuth carboxylate and an organic phosphite triester. The polyurethane resin compositions are suited for use as adhesives for bonding low-polarity resin bases such as polyolefin films.