Cationic electrophoretic coating compositions

Claim 1

A cationic electrophoretic coating composition comprising an aqueous medium and a resinous binder dispersed therein, said resinous binder comprises: (A) A water-soluble or water-dispersible resin prepared by contacting a reaction product with a partially blocked polyisocyanate having in the molecule not more than one free isocyanate group and at least one blocked isocyanate group on the average at a temperature of 40° to 130° C., and subsequently by neutralizing the resulting product with an acid, said reaction product being prepared by reacting a compound selected from the group consisting of fatty acid, polyamide or mixtures thereof with an adduct, said adduct being prepared by reacting an epoxy resin with a basic amino compound, the amount of said fatty acid and/or polyamide used being 1 to 100 parts by weight per 100 parts by weight epoxy resin and the basic amino compound being used in an amount not exceeding one mole per mole of epoxy group and (B) at least one polymer selected from the group consisting of an ethylene oxide addition polymer, a propylene oxide addition polymer and derivatives of the ethylene oxide addition polymer and/or propylene oxide addition polymer, said polymers and derivatives having a number average molecular weight of 500 to 10,000 and having a solubility of up to 60 parts by weight in 100 parts by weight of water at 25° C., the partially blocked polyisocyanate being used in an amount of 1 to 100 parts by weight per 100 parts by weight of the epoxy resin and the component (B) being used in an amount of 0.5 to 30% by weight based on the component (A) as solid.