SURFACE-TREATED STEEL SHEET

摘要

PROBLEM TO BE SOLVED: To provide a chromate-coated surface-treated steel sheet capable of improving working adhesion after coating resin and excellent in adhesion with adhesives and a resin layer and strength of chromate coating film itself. SOLUTION: This chromate-coated surface-treated steel sheet is the one in which the surface of a galvanized steel sheet is applied with a chromate coating film. This chromate coating film is composed of trivalent chromium in which the weight ratio of the content of trivalent chromium/the total content of chromium is regulated to 0.2 to 0.5, vapor phase silica in which the weight ratio of trivalent chromium and SiO2 /the total chromium is regulated to 1.0 to 2.0 and a silane coupling agent in which the molar ratio of vapor phase silica and the silane coupling agent/the total chromium is regulate to 1×10<-2> to 5×10<-2> , and its coating weight is regulated to 10 to 60 mg/m<2> by that of the total chromium.