Patent ID: 7005051

Claim:
A process for forming a layered coated film comprising: a step I in which an electrodeposition coated film is formed on a substrate to be coated by an electrodeposition coating process with using a cationic electrodeposition coating composition, and the electrodeposition coated film is heated to form a cured electrodeposition coated film; a step II in which an intermediate coating composition is applied to the cured electrodeposition coated film to form an uncured intermediate coated film; a step III in which a base coating composition is applied to the uncured intermediate coated film to form an uncured base coated film; a step IV in which a clear coating composition is applied to the uncured base coated film to form an uncured clear coated film; and a step V in which the uncured intermediate coated film, base coated film, and clear coated film are simultaneously heated and cured; wherein the cationic electrodeposition coating composition is a lead-free cationic electrodeposition coating composition which comprises an aqueous medium, a binder resin composed of a cationic epoxy resin and a blocked isocyanate curing agent dispersed or dissolved in the aqueous medium, a neutralizing acid in order to neutralize the cationic epoxy resin, an organic solvent, and a metal catalyst, and which has a volatile organic content of 1% by weight or less, a metal ion content of 500 ppm or less, a neutralizing acid amount of 10 to 30 mg equivalent based on 100 g of binder resin solid content, and the intermediate coating composition comprises a resin component composed of 10 to 70% by weight solid based on total resin solid of a hydroxyl group containing resin (a), 10 to 70% by weight of a curing agent reactable with hydroxyl group (b), 18 to 50% by weight of a nonaqueous dispersion resin (c), with the proviso (a)+(b)+(c)=100%, and a pigment component.