CHEMICALLY CONVERTED Zn-BASED METAL PLATED STEEL SHEET AND PRODUCTION METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a chemically converted Zn-based metal plated steel sheet having a chemical conversion coating film containing an organic resin, which is excellent in weatherability, water resistance, blackening resistance, and coating film adhesiveness.

SOLUTION: Solution of chemical conversion treatment is applied onto a surface of an Al-containing Zn-based alloy plated steel sheet, and dried to form a chemical conversion coating film having a film thickness of 0.5-10 μm. The solution of chemical conversion treatment contains: fluorine-containing resin containing, by mass, 0.05-5% reactive functional group and 7-20% F atoms while the number-average molecular weight is within the range of 1,000-80,000; an organic crosslinking agent having a functional group to be reactive with the reactive functional group; and group 4A metal compounds. The amount of the organic crosslinking agent to the amount of fluorine-containing resin in the solution for chemical conversion treatment is within the range of 0.8-9.6%. The amount of the group 4A metal compounds to the amount of fluorine-containing resin in the solution for chemical conversion treatment is within the range of 0.1-5% in terms of metal.

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