| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface-treated steel sheet which remarkably inhibits red rust from initiating from the portion at which basis steel in a cut end face is exposed in an outdoor environment, by a chrome-free surface treatment technique. SOLUTION: The painted steel sheet has a paint film formed thereon which contains particles of an alkaline earth metal compound, particles of a zinc compound, particles of a phosphate particle, and particles of an organic carboxylate as needed. The paint film contains each particle so that when the painted steel sheet sample is immersed in pure water of atmospheric temperature, the molar ratio of the eluted quantities per hour of components which elute from the paint film can satisfy the following expressions (1): 0.95≤([alkaline earth metal element]+Zn)/P, and (2): 0.1≤[alkaline earth metal element]/Zn≤10, and so that the quantity of eluted P can be in a range of 0.5 to 30 mmol in terms of a value per square meter of the paint film area. COPYRIGHT: (C)2008,JPO&INPIT
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