Abstract: Thermosetting coating compositions are based on a binder comprising carboxyl functional polyurethane, acrylic copolymer, and if desired a carbodiimide crosslinker. The binder is produced by synthesizing an isocyanate terminated, carboxyl functional urethane prepolymer in the absence of water and organic solvent but in the presence of ethylenic monomers. The organic phase urethane prepolymer dispersed in ethylenic monomers is inverted into water whereupon the urethane prepolymer is extended by reaction with a primary or secondary polyamine such as diamine to produce a high molecular weight polyurethane-urea. Thereafter, the ethylenic monomers are copolymerized to form an aqueous dispersed polyurethane-urea and acrylic copolymer mixture. The resulting polymeric binder is useful in protective surface coatings applied to plastic substrates. A carbodiimide can be added to provide thermosetting crosslinking with the carboxyl functional polyurethane.

Abstract: Transesterification curing of ester polymers and hydroxyl polymers is effected by the inclusion of a transesterification catalyst comprising a catalytic amount of epoxy resin and certain inorganic salts.