发明名称 |
Precoated steel sheet having improved corrosion resistance and formability |
摘要 |
A precoated steel sheet having improved corrosion resistance and formability is disclosed, which comprises a Zn- or Zn alloy-plated steel sheet having on the plated surface either a colloidal silica-containing chromate undercoat layer and a polyhydroxypolyether resin-based topcoat of 0.3 to 10 mu m in thickness in which resin is derived by polycondensation of a dihydric phenol component selected from a mononuclear dihydric phenol, dinuclear dihydric phenol, and a mixture of both, with an epihalohydrin or a non-colloidal material-containing chromate underlayer and an epoxy resin based topcoat containing colloidal silica of a thickness of from 0.3-1.6 mu m in thickness. In spite of the absence of zinc powder, the precoated steel sheet can be satisfactorily welded by resistance welding when the thickness of the topcoat layer is not greater than 2.5 mu m, and even with such a thin topcoat, the precoated steel sheet retains its improved corrosion resistance and formability. The precoated steel sheet can be satisfactorily finish-coated by electrodeposition. The undercoat layer is produced by a two stage reduction of Cr+6 to Cr+3 in an aqueous suspension containing chromic acid.
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申请公布号 |
US5141822(A) |
申请公布日期 |
1992.08.25 |
申请号 |
US19900620449 |
申请日期 |
1990.12.03 |
申请人 |
SUMITOMO METAL INDUSTRIES CO., LTD. |
发明人 |
MATSUO, SACHIO;SHIOTA, TOSHIAKI;ITOH, MAKI;KAWAGUCHI, HIDEO;HANABATA, HIROKI;YOSHIKAWA, YUKIHIRO;TAKA, TAKAO;FUKUI, KIYOYUKI |
分类号 |
B05D7/14;B05D7/24;B32B15/08;B32B15/092;C23C22/30;C23C28/00 |
主分类号 |
B05D7/14 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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