Abstract: A method for forming a multilayer coating film which includes forming an uncured coating film by applying a first aqueous base coating composition, forming an uncured coating film by applying a second aqueous base coating composition, forming an uncured coating film by applying a clear coating composition, and simultaneously heat curing the obtained coating films. The first aqueous base coating composition contains a carbodiimide compound, the clear coating composition contains a hydroxyl group-containing acrylic resin (A) having a hydroxyl value of 120 to 160 mgKOH/g and an acid value of 5 to 10 mgKOH/g, a polyisocyanate compound (B), and a polycarbonate diol compound (C). The component (A) has a hydroxyl group-containing alkyl moiety having 3 or less carbon atoms, and the ratio of the numbers of moles of the isocyanate functional groups of the component (B) and the hydroxyl group functional groups of the component (A) is 1.15 to 1.35.

Abstract: A method for forming a multilayer coated film includes step (1) of applying an aqueous intermediate coating composition (A), step (2) of applying an aqueous base coating composition (B), step (3) of applying a clear coating composition (C), and step (4) of heat-curing the coated films. The coating composition (A) contains a specific hydroxyl group-containing acrylic resin (a1), a specific polyurethane resin (a2), a specific hydroxyl group-containing polyester resin (a3), a melamine resin (a4), and an active methylene-blocked polyisocyanate compound (a5). A ratio of the resin (a1) to the resin (a2) falls within a specific range. The heat-cured coated film of the coating composition (A) has a specific elongation at break, Young's modulus and Tukon hardness. The coating composition (C) contains a hydroxyl group-containing acrylic resin (c1) and an allophanate group-containing polyisocyanate compound (c2).

Abstract: A method for forming a multilayer coating film which includes forming an uncured coating film by applying a first aqueous base coating composition, forming an uncured coating film by applying a second aqueous base coating composition, forming an uncured coating film by applying a clear coating composition, and simultaneously heat curing the obtained coating films. The first aqueous base coating composition contains a carbodiimide compound, the clear coating composition contains a hydroxyl group-containing acrylic resin (A) having a hydroxyl value of 120 to 160 mgKOH/g and an acid value of 5 to 10 mgKOH/g, a polyisocyanate compound (B), and a polycarbonate diol compound (C). The component (A) has a hydroxyl group-containing alkyl moiety having 3 or less carbon atoms, and the ratio of the numbers of moles of the isocyanate functional groups of the component (B) and the hydroxyl group functional groups of the component (A) is 1.15 to 1.35.

Abstract: A method for forming a multilayer coated film includes step (1) of applying an aqueous intermediate coating composition (A), step (2) of applying an aqueous base coating composition (B), step (3) of applying a clear coating composition (C), and step (4) of heat-curing the coated films. The coating composition (A) contains a specific hydroxyl group-containing acrylic resin (a1), a specific polyurethane resin (a2), a specific hydroxyl group-containing polyester resin (a3), a melamine resin (a4), and an active methylene-blocked polyisocyanate compound (a5). A ratio of the resin (a1) to the resin (a2) falls within a specific range. The heat-cured coated film of the coating composition (A) has a specific elongation at break, Young's modulus and Tukon hardness. The coating composition (C) contains a hydroxyl group-containing acrylic resin (c1) and an allophanate group-containing polyisocyanate compound (c2).