A cross self-curing system for an aqueous-based PU hybrid

Isocyanate (NCO)-terminated polyurethane (PU) prepolymer comprises carboxylic acid, which is obtained from a conventional PU preparation procedure. Aziridine-terminated PU oligomer is prepared by an addition reaction of aziridine to NCO-terminated PU prepolymer after it is neutralized with triethylamine. This PU oligomer is then dispersed with water and becomes a single-component self-curable aqueous-based PU dispersion (PU-AZ). PU carboxyl groups are not only the ionic centers stabilizing the aqueous polymer dispersion, but also serve as PU curing sites toward the curing reaction with its aziridine terminal groups on drying. This self-curable PU-AZ dispersion is miscible and compatible with other carboxyl groups containing aqueous-based PU dispersion in any ratio, which results in a cross self-cured PU hybrid formation on drying. This cross self-cured PU hybridization process allows property modification and the curing of PU simultaneously without the addition of any external curing agent. (c) 2005 Wiley Periodicals, Inc.