SURFACE TREATMENT LIQUID FOR GALVANIZED STEEL SHEET, METHOD FOR PRODUCING GALVANIZED STEEL SHEET HAVING SURFACE TREATMENT FILM, AND GALVANIZED STEEL SHEET HAVING SURFACE TREATMENT FILM

摘要

Disclosed is a surface-treatment solution for producing a zinc or zinc alloy coated steel sheet with a surface-coating layer that does not contain a chromium compound in the surface-coating layer and that is excellent in all of heat discoloration resistance, heat cracking resistance, planar part anti-corrosion property, corrosion resistance after alkali degreasing, blackening resistance, stack blackening resistance, anti-water stain property, solvent resistance, perspiration resistance, coating adhesion property, and storage stability. The disclosed surface-treatment solution contains a glycidyl group-containing silane coupling agent (A), a tetraalkoxysilane (B), a zirconium carbonate compound (C), and an anionic polyurethane resin (D) having a glass transition temperature (Tg) of 80 °C to 130 °C, a vanadium compound (E), a molybdic acid compound (F), and water, the surface-treatment solution having a pH of 8.0 to 10.0, and the amount of each component satisfying a predetermined relationship.