| 摘要 |
PROBLEM TO BE SOLVED: To provide an aqueous base coating composition capable of forming a coating film excellent in coating film appearance and adhesiveness to a coated material without preliminary heating after forming a first base coating film in a multilayer coated film forming method based on the 3C1B system.SOLUTION: There is provided an aqueous base coating composition comprising a core/shell type emulsion resin as a base resin in which the mass content ratio between a core part and a shel part is 20/80 to 80/20, the core part is composed of an acrylic resin and the shell part is composed of a polyurethane resin, wherein the acrylic resin has a hydroxyl value of 40 to 140 mgKOH/g and an acid value of 0 to 10 mgKOH/g, the polyurethane resin has a hydroxyl value of 20 to 80 mgKOH/g and an acid value of 10 to 60 mgKOH/g, and in the polyurethane resin, the total mass content ratio of a constitutional unit based on a dibasic acid and/or a dihydric alcohol having 10 to 60 carbon atoms is 10 to 50 mass% based on the resin solid content of the polyurethane resin. |
