SURFACE-TREATED STEEL SHEET AND WATER-BASED SURFACE TREATMENT SOLUTION USED THEREFOR

摘要

PROBLEM TO BE SOLVED: To prevent early red rust formation encountered when a surface-treated steel sheet being a zinc-plated steel sheet or an aluminum plated steel sheet subjected to chromium-free surface treatment is in close contact with a copper member.SOLUTION: The outermost layer of a surface treatment film has (A) a resin of a Tg of -10°C or more selected from an acrylic resin, a polyester resin, and an urethane resin, (B) colloidal silica, (C) a zirconium compound, and (D) a compound selected from triazoles and tetrazoles, and optionally (E) a solid lubricant, (F) a vanadium compound, and (G) silica having an average particle diameter of 0.1 m or more, an oil absorption of 50 mL/100 g or more in the following ratios: B/A of 0.080-0.25, C/A of 0.050-0.20, D/(A+B+C+D) of 0.003-0.13, E/(A+B+C+D) of 0.030-0.23, F/(A+B+C+D) of 0.005-0.10 or less, and G/(A+B+C+D) of 0.010-0.29.