Abstract: In a cationic electrodeposition process for coating an electric conductive substrate as a cathode with an electrodeposition process-coating composition containing a resin; an improvement characterized in that said resin is a resin having hydroxyl groups, tertiary amino groups, quaternary ammonium groups and blocked isocyanate groups which are reactive with hydroxyl group at an elevated temperature which is obtained by reacting(a) a polyisocyanate;(b) a polyhydroxyl compound;(c) a hydroxyl compound having tertiary amino group;(d) a hydroxyl compound having quaternary ammonium group; and(e) a monofunctional blocking agent.The coated layer has excellent anticorrosive characteristic, mechanical characteristics and the coating composition has excellent stability for aging.

Abstract: A cationic electrodeposition-coating resin is prepared by reacting(1) a polyisocyanate with(2) a polyol and(3) a monofunctional blocking agent at a molar ratio of excess of isocyanate groups to total of hydroxyl groups of the polyol and functional groups of the monofunctional blocking agent to obtain an intermediate (A) having isocyanate groups; and reacting a tertiary amine having at least two hydroxyl groups with the intermediate (A) at a molar ratio of excess of hydroxyl groups of the tertiary amine to isocyanate groups of the intermediate (A); and cationizing the resulting reaction product (B).