Patent ID: 7264705

Claim:
An improved cathodic electrocoating composition, comprising an aqueous carrier having dispersed therein a film forming binder comprising an epoxy-amine adduct and a blocked polyisocyanate crosslinking agent; wherein the improvement is the incorporation of an anti-crater agent comprising a highly branched water-reducible polyester which is the reaction product of: (a) a hydroxy cyclic carbonate; (b) an aliphatic polycarboxylic acid anhydride; (c) optionally, a monofunctional epoxy resin; (d) a bridging agent selected from the group consisting of di and higher polyisocyanate resin; (e) a polyamine compound selected from the group consisting of (i) a polyamine having at least one free tertiary amine and one primary or secondary amine group; and (ii) a combination of a polyamine having at least one free tertiary amine and one primary or secondary amine group, and an aminoalkylalkoxysilane, which reaction product is neutralized in the presence of acid and water to convert the tertiary amine groups to water-dilutible groups.