| 摘要 |
PROBLEM TO BE SOLVED: To obtain excellent corrosion resistance, blackening resistance, dew condensation resistance, chromium elution resistance, adhesiveness to an adhesive tape, and roll formability. SOLUTION: This surface treated steel sheet has a coating containing (A) a particular copolymer resin, (B) a chromium compound, and (C) phosphoric acid, as a main component, formed on the surface of an Al-Zn alloy plated steel sheet, wherein (A) comprises 30-60 mass% of styrene, 0.5-5 mass% of (meth) acrylic acid, and 20-60 mass% of (meth) acrylate having a 3-6C alkyl chain; (B) has a ratio of hexavalent chromium [Cr<SP>6+</SP>/(Cr<SP>3+</SP>+Cr<SP>6+</SP>)] in a range of 0.3-0.9 in terms of metallic chromium, and a mass ratio of a solid content of the above (A) to the above (B) in terms of metallic chromium, in a rage of 10-200, while the coating contains 1-100 mg/m<SP>2</SP>of Cr; and a mass ratio of PO<SB>4</SB>contained in the (C) to chromium contained in the (B) in terms of metallic chromium, PO<SB>4</SB>/Cr, is in the range of 0.1-3. COPYRIGHT: (C)2003,JPO
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