| 摘要 |
PROBLEM TO BE SOLVED: To improve corrosion resistance without impairing a coating in pressing by a method wherein a resin coating wherein respective specific weight proportions of polyethylene resin, chromate, and silica are mixed in a coating composition composed of a mixture of urethane prepolymer containing hydroxyl group and hardener, is provided to a chromate coating provided on a surface. SOLUTION: A chromate coating of 5-200mg/m<2> coating weight (in terms of metallic chromium) is provided on a surface. A coating composition wherein a hardener consisting of block isocyanate prepolymer and/or amino resin is mixed in a mixture of urethane prepolymer containing at least two kinds of hydroxyl groups of different glass transition temperatures which is composed of specific polyol, isocyanate compound, and bivalent alcohol, is applied onto that. In that case, 1-30 pts.wt. per 100 pts.wt. of the solid content of the coating composition of polyethylene resin of at most 130 deg.C melting point and respective specific weight proportions of chromate and silica are blended, and hardened by heating to form a resin coating of 0.3-10μm thickness.
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