CHEMICAL-CONVERSION-TREATMENT-PLATED STEEL SHEET AND METHOD FOR MANUFACTURING SAME

摘要

The surface of an Al-containing Zn-alloy-plated steel sheet is coated with a chemical conversion treatment liquid, which is dried to form a chemical conversion treatment film having a thickness of 0.5-10 mum. The chemical conversion treatment liquid contains: a fluororesin which includes 0.05-5 wt% of a hydrophilic functional group and 7-20 wt% of F atoms, the fluororesin having a number-average molecular weight within the range of 1,000-2,000,000; an oxygen acid salt, fluoride, hydroxide, organic acid salt, carbonate, or peroxide salt of a group 4A metal; and resin particles having an average particle size of 0.1-10 mum. The amount of the oxygen acid salt, fluoride, hydroxide, organic acid salt, carbonate, or peroxide salt of a group 4A metal relative to the fluororesin in the chemical conversion treatment liquid is within the range of 0.1-5 wt% expressed as metal.