| abstract |
PROBLEM TO BE SOLVED: To provide a method for producing a galvanized steel sheet containing hexavalent chromium, having no discharge in the production process, and having the same corrosion resistance and paint adhesion as conventional chromate treatment. SOLUTION: The surface treatment method for a zinc-based plated steel sheet, in which a zinc-based plated steel sheet is treated with an aqueous solution essentially containing (A) to (D), and is washed with water and dried to form a film. (A) Acrylic copolymer fine particles obtained by emulsion polymerization of (a) to (e), (a) (meth) acrylate monomer, (b) α, β having a carboxyl group in the molecule -Ethylenically unsaturated monomer, (c) α, β-ethylenically unsaturated monomer having a glycidyl group in the molecule, (d) α, β-ethylenically unsaturated monomer having an alkoxysilane group in the molecule Monomers, (e) monomers copolymerizable with the above (a) to (d), (B) urethane-based resin fine particles, (C) olefin-based copolymer fine particles, and (D) colloidal silica fine particles. |