| 摘要 |
PROBLEM TO BE SOLVED: To improve weatherability, processability, and corrosion resistance in a processed part, and to prevent environmental pollution at the time of disposal by forming, on a surface-treated metallic sheet, an undercoat layer of a resin coating containing a rust preventive pigment, an intercoat layer of a high-molecular resin coating having specifie molecular weight, and a topcoat layer of a resin coating so that each coating has a specific thickness. SOLUTION: A resin coating containing a rust prevention pigment is applied on the surface of a surface-treated metallic sheet 1 to form an undercoat layer 2 having 2-15μm thickness, and a high-molecular resin coating having number- average molecular weight of 5,000 or higher is applied thereon to form an intercoat layer 3 having 10-30μm thickness, and a resin coating is coated thereon to form a topcoat layer 4 having a thickness of 7-30μm. A backcoat layer 5 is applied on the back side of the metallic sheet 1 for corrosion prevention. The metallic sheet 1 is subjected to the surface treatment by chromate treatment or the like before applying coating. The undercoat layer 2 is formed of an epoxy resin coating or the like, the intercoat layer 3 is formed of a high- molecular polyester resin coating, and topcoat layer 4 is formed of an acrylic resin coating, where each coating is applied by a roller to be baked and dried.
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