| 摘要 |
PURPOSE:To improve the corrosion resistance and paint film adhesiveness of a chromate film by adding specific water-soluble high polymer to a chromate soln. treating the surfaces of Zn-plated materials and Al alloy materials. CONSTITUTION:The water soluble high polymer of polyacrylic amide or polymethacrylic amide expressed by the general formula [I] is added at 0.1-5g/l to the chromate treating soln. of an aqueous soln. contg. mineral acids such as sulfuric acid and nitric acid, and fluoride such as NaF to hexavalent Cr compounds such as CrO3, Na2Cr2O7 at the time of chromate-treating the surfaces of Zn and Zn-plated materials or Al and Al alloys. [X in the formula is H and/or CH3, Y is the mixture of COOZ (Z is H or alkali metal atoms) and -CONH2, and n is 1,000-30,000]. After the materials are chromate-treated with this chromate treating soln., they are immersed in an aqueous soln. contg. multivalent metallic salts such as sulfates, nitrates of alkaline earth alkaline earth metals like Ca, Ba, Mg, etc. and Mn, Cr, etc., whereby the chromate film of superior corrosion resistance and adhesiveness is formed. |
