Aqueous urethane-epoxy coating composition

摘要

An ambient temperature-curing aqueous urethane-epoxy emulsion coating composition is provided comprising an essentially organic solvent-free emulsion in water of: (a) a urethane oligomer, terminated with primary amine functional groups which are reactive with epoxides, said oligomer being the reaction product of an isocyanate-terminated polyurethane prepolymer and a mono- or polyketimine compound containing one other functional group bearing a single active hydrogen atom which reacts with the isocyanate groups to yield a ketimine-terminated urethane oligomer, said ketimine-terminated urethane oligomer being emulsified into the water by conversion of the ketimine groups into primary amine groups and formation of acid salt of 25-50% of the amine groups by a volatile organic acid; and (b) a polyepoxide in an amount sufficient to provide a ratio of total primary amino group hydrogen atoms to epoxide groups of about 0.9 to 2.