SURFACE TREATED TIN-PLATED STEEL SHEET AND CHEMICAL TREATMENT SOLUTION

摘要

A surface treated tin-plated steel sheet which has (1) an alloy layer formed on the surface of a steel sheet, (2) a tin plating layer being formed on said alloy layer with a remaining exposed portion of the alloy layer having an area of 3.0 % or more of that of said alloy layer and, formed on said tin plating layer and said exposed portion of the alloy layer, (3) a coating film containing P and Si in an amount of 0.5 to 100 mg/m<2> and 0.1 to 250 mg/m<2>, respectively; and a chemical treatment solution for use in preparing the steel sheet which comprises a phosphate ion, a tin ion and a silane coupling agent and has a pH of 1.5 to 5.5. The surface treated tin-plated steel sheet is free from chromium which causes problems from an environmental view point, and also is excellent in adhesion with a paint, corrosion resistance after being coated, rust resistance, and formability.