Patent ID: 8304092
Filing Date: 2012-11-06
Classification: C09D,C23C,Y10T

Abstract:
1. An aqueous surface-treatment liquid for a galvanized steel sheet having superior flat-portion corrosion resistance, blackening resistance, and appearance and corrosion resistance after press forming, comprising a water-soluble zirconium compound (A) selected from the group consisting of sodium zirconium carbonate and ammonium zirconium carbonate; water-dispersive particulate silica (B); a silane coupling agent (C) selected from the group consisting of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and γ-aminopropyltrimethoxysilane; a vanadic acid compound (D) selected from the group consisting of sodium vanadate and ammonium vanadate; a phosphoric acid compound (E) selected from the group consisting of phosphoric acid, ammonium phosphate and diphosphonic acid; a nickel compound (F) selected from the group consisting of nickel nitrate hexahydrate and nickel sulfate hexahydrate; and an acrylic resin emulsion (G) selected from the group consisting of styrene-ethylmethyacrylate-n-butylacrylate-acrylic acid and methylmethacrylate-2-ethylhexylacrylate-acrylic acid, so as to satisfy the following conditions (1) to (7): (1) the mass ratio (B)/(A) of the amount of water-dispersive particulate silica (B) to the amount of water-soluble zirconium compound (A) on a zirconium basis=0.1 to 1.2; (2) the mass ratio (C)/(A) of the amount of silane coupling agent (C) to the amount of water-soluble zirconium compound (A) on a zirconium basis=0.5 to 3.0; (3) the mass ratio (D)/(A) of the amount of vanadic acid compound (D) on a vanadium basis to the amount of water-soluble zirconium compound (A) on a zirconium basis=0.02 to 0.15; (4) the mass ratio (E)/(A) of the amount of phosphoric acid compound (E) on a phosphorus basis to the amount of water-soluble zirconium compound (A) on a zirconium basis=0.03 to 0.30; (5) the mass ratio (F)/(A) of the amount of nickel compound (F) on a nickel basis to the amount of the water-soluble zirconium compound (A) on a zirconium basis=0.005 to 0.10; (6) the mass ratio (SI)/(A) of the total amount (SI) of water-dispersive particulate silica (B) and silane coupling agent (C) on a silicon basis to the amount of water-soluble zirconium compound (A) on a zirconium basis=0.15 to 1.0; and (7) the mass ratio (G)/(X) of the solid content of the acrylic resin emulsion (G) to the total solid content (X) of the aqueous surface-treatment liquid=0.005 to 0.18.