Process for making aqueous cationic coating from amine-epoxy adduct, polyamide, and semiblocked polyisocyanate, acid salt, and product

A process for preparing a cationic electrophoretic coating composition comprising the steps of:

• (I) mixing or reacting
• (1) a reaction product of an epoxy-amine adduct
• (A) and a partially blocked polyisocyanate
• (C) in the weight ratio of from 95 to 5 of
• (A) to from 5 to 95 of (C) and
• (2) a reaction product of a polyamide (B) and a partially blocked polyisocyanate (C) in the weight ratio of from 95 to 5 of (B) to from 5 to 95 of (C),
• said epoxy-amine adduct (A) being a reaction product prepared by reacting an epoxy resin with a basic amino compound having at least one basic amino group, said polyamide (B) being a polyamide having at least one basic amino group and said partially blocked polyisocyanate (C) being a polyisocyanate compound having at least one blocked isocyanate group in the molecule and an average of more than zero to not more than one free isocyanate group per molecule, and the weight ratio being from 90 to 10 of said reaction product of (A) and (C) to from 10 to 90 of said reaction product of (B) and (C) and
• (II) dissolving or dispersing the resulting mixture or reaction product in an aqueous medium by neutralization with an acid.