| 摘要 |
A surface-treated steel sheet has a zinc-based or an aluminum-based plated steel sheet, a surface-treatment coating being formed on the surface of the zinc-based or aluminum-based steel sheet by applying and drying a surface treatment coating composition thereon, and a top coating being formed by applying, and drying a coating composition for top coating on the surface-treatment coating. The surface treatment coating composition contains a water-epoxy resin dispersion, a water dispersed polyurethane resin, a silane coupling agent, and phosphoric acid and/or a hexafluorometal acid. The coating composition for a top coating contains a high molecular weight epoxy group-containing resin average molecular weight of 6,000 to 20,000.
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