| 摘要 |
PROBLEM TO BE SOLVED: To improve the white rust resistance of the steel sheet at a low cost by providing the surface of a galvanizing layer with an organic resin layer contg. one or more kinds among the alkali metal salts of molybdic acid, titanic acid, zirconic acid or vanadic acid, alkaline-earth metal salts and ammonium salts and metallic oxides. SOLUTION: As the organic resin, the one obtd. by adding a resin using a phenol resin, an epoxy resin or the like as the skelton with an amino group, an imino group or the like can be used, and the molecular weight is desirably controlled to thousands to tens of thousands. Preferably, the coating weight (solid content) of the organic resin layer is controlled to 50 to 600 mg/m2, and the organic resin is contained by 0.5 to 15 wt.% in the solid content. The weight ratio of the metallic oxides to the Mo, Ti, Zr and V in the acid salts in the organic resin layer is preferably controlled to the range of 1 to 6. As the metallic oxides, the oxides of Si, Sn, Ti, Sb, W, Fe or the like are preferable.
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