PRECOATED STEEL SHEET EXCELLENT IN CORROSION RESISTANCE

摘要

PROBLEM TO BE SOLVED: To produce a precoated steel sheet subjected to rust preventing treatment instead of chromate treatment and excellent in corrosion resistance. SOLUTION: The surface of a steel sheet is provided with a film layer contg. a resin of 100 pts.wt. expressed in terms of the solid content and at least a vanadic compd. of 0.1 to 100 pts.wt. and furthermore optionally contg. at least one kind among a thiocarbonyl group-contg. compd. of 0.1 to 300 pts.wt., a phosphoric compd. of 0.01 to 300 pts.wt. (as PO4) and particulate silica of 1 to 2000 pts.wt. as a substrate treated layer, moreover, the surface is provided with a colored upper film layer, or with an under coat layer contg. rust preventive pigment and a colored upper film layer or with an upper film layer contg. rust preventive pigment.