Paint composition for cationic electrodeposition process

Claim 1

A paint composition for cationic electrodeposition in the form of an aqueous solution or dispersion, essentially prepared by: (a) reacting a carboxyl terminated polymer of a conjugated diene or a carboxyl terminated copolymer of a conjugated diene and vinyl monomer with a bisphenol A-epichlorohydrin epoxy resin condensate, in an amount of at least one equivalent part of the epoxy group of the latter in proportion to one equivalent part of the carboxyl group of the former at a temperature of about 80° C. to about 200° C. until the carboxyl group may be substantially eliminated to produce a reaction intermediate; (b) reacting said intermediate with a primary amine or a secondary amine compound, in an amount of not more than one equivalent part of said amine compound in proportion to one equivalent part of the epoxy group of said intermediate at a temperature of about 50° C. to about 150° C. to obtain an epoxy-amine adduct first component having an amine value of 20 to 200; (c) reacting said first component with a partial block isocyanate compound as a second component, the ratio of said first and second components being selected as 99 to 55 percent by weight of the former to 1 to 50 percent by weight of the latter component; and, (d) neutralizing the resultant resin with an acid to render the resultant resin soluble or dispersible in water.