| 摘要 |
PROBLEM TO BE SOLVED: To provide a non-chromium series precoated steel sheet excellent in corrosion resistance. SOLUTION: As this hexavalent chromium-free precoated steel sheet excellent in corrosion resistance, a precoated steel sheet in which a steel sheet whose both sides are subjected to substrate treatment free from hexavalent chromium or a plated steel sheet is used as an original sheet, the face being the surface of the steel sheet is provided with two coating film layers of a lower coating film layer and an upper coating film layer, and, further, the face being the back of the steel sheet is provided with one coating film layer of a back side coating film layer, both of the lower layer coating film layer and the back side coating film layer contain rust preventive pigment in which Ca2+ ions are adsorbed on an SiO2 carrier.
|
