| 摘要 |
PURPOSE:To improve the corrosion resistance of a zinc plated steel sheet and the adhesive strength to a paint film by depositing a specified intermediate on the surfaces of the steel sheet, forming a film on the intermediate by chemical conversion treatment, and further forming a resin film. CONSTITUTION:A Zn or Zn alloy plated steel sheet is treated with a surface conditioning liq. prepd. by adding >=1 kind among the water soluble sulfates and hydrochlorides of Fe, Co and Ni to a mixed aqueous soln. contg. hydrochloric acid and sulfuric acid to deposit an intermediate consisting of said metals and the oxides thereof by 10-200mg/m<2> when expressed in terms of metals. The steel sheet is washed, and an aqueous soln. contg. chromic acid, phosphoric acid, malonic acid and boric acid is applied to the intermediate and dried to form a chromate film contg. 20-300mg/m<2> Cr. An acrylic resin film of 0.1- 2.5mum thickness contg. 1-10wt% chromic acid, chromate such as sodium chromate, potassium chromate or ammonium chromate, or dichromate is formed on the chormate film. |
