| 摘要 |
PURPOSE:To develop the title chromated steel sheet having excellent corrosion resistance, paint adhesion, fingerprint resistance, etc., by forming a first-layer film contg. Cr and Si on the surface of a galvanized steel sheet, and further forming a second-layer film contg. P, S, org. resin, etc., on the first-layer film. CONSTITUTION:A galvanized steel sheet or a Zn-based alloy plated steel sheet is dipped in an aq. soln. contg. CrO3 and colloidal silica, roll-down, and then dried to form a first layer contg. >=5mg/m<2> Cr and >=5mg/m<2> Si and wherein Si/Cr=0.1-5 on the surface. A processing soln. contg. phosphoric acid, colloidal silica, >=2 kinds among the water-soluble or water-dispersible org. resins such as acrylamide resin, and further ZrCrO3, as required, is applied on the first layer and then dried to form the second-layer coating film contg. >=1mg (P+Si+ org. resin) and wherein Si/(Si+org. resin)=0.1-10, P/(Si+org. resin)=0.1-10, and Cr/(P+Si+org. resin)<=0.2. A two-layer chromated steel sheet is thus obtained. |
