PRODUCTION OF ZN ALLOY PLATED STEEL SHEET HAVING EXCELLENT CORROSION RESISTANCE, PAINTABILITY, SOLVENT RESISTANCE, ALKALI RESISTANCE AND FINGERPRINT RESISTANCE

摘要

PURPOSE:To improve corrosion resistance, paintability, solvent resistance, alkali resistance and fingerprint resistance by coating an aq. soln. of a specific compsn. contg. a carboxylated polyolefin resin on a Zn alloy having a chromate film and drying the coating. CONSTITUTION:The chromate film of 5-200mg/m2 Cr deposition is formed on the surface of the Zn or Zn alloy plated steel sheet. An aq. soln. of the compsn. contg. 5-50pts.wt. liquid epoxy resin and 5-60pts.wt. colloidal silica in solid content in 100pts.wt. in solid content of water soluble or water dispersible resin of carboxylated polyolefin contg. 3-20mol% -CH2H is coated thereon. The coating is dried at =60 deg.C sheet temp. to form the film and is so treated that the deposition thereof is 0.3-3g/m2. The Zn or Zn alloy plated steel sheet having the excellent corrosion resistance, paintability, solvent resistance, alkali resistance and fingerprint resistance and having the weldability as well is thus obtd.