| 摘要 |
PROBLEM TO BE SOLVED: To impart excellent corrosion resistance to a steel sheet in a non- pollutive state by forming a film of an organic resin contg. a specified amt. of ion exchange silica to have a specified thickness, on the surface of a galvanized steel sheet or an aluminum plated steel sheet. SOLUTION: On the surface of a galvanized steel sheet (such as a Zn-Ni alloy plated steel sheet) or an aluminum plated steel sheet (such as an Al-Si alloy plated steel sheet), an organic film with 0.1 to 5μm film thickness contg. ion exchange silica by 1 to 100 pts.wt. (solid content) to 100 pts.wt. (solid content) of organic resin for forming film is formed. As the organic resin, an organic high polymer resin having an OH and/or COOH group, desirably, an epoxy resin (such as bisphenol A) and/or a modified epoxy resin (such as an epoxy ester resin) is used, by which a dense barrier film is formed. The ion exchange silica is the one obtd. by fixing the metallic ions of calcium, magnesium or the like to the surface of porous silica gel powder and is blended as a rust preventive additive.
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