| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a chromium-free surface-treated galvanized steel sheet having an underlayer as a bonding layer and then an upper coating layer formed thereon by two-step treatment, and having both superior corrosion resistance and superior adhesiveness of a surface treatment film to a base plated steel sheet. SOLUTION: The method for manufacturing the chromium-free surface-treated galvanized steel sheet having a bonding layer formed on a galvanized steel sheet or a zinc alloy-plated steel sheet by a coating agent containing an organic resin, a silane coupling agent and silica, and a functional organic coating layer formed on the bonding layer by a coating agent for forming the functional organic coated layer, is characterized by alkali-cleaning treatment applied onto the plated steel sheet prior to the application of the coating agent for forming the bonding layer onto the plated steel sheet. To the coating agent for forming the bonding layer, tannic acid may be further blended. COPYRIGHT: (C)2004,JPO&NCIPI
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