Surface treatment liquid for galvanized steel sheet, method for producing galvanized steel sheet with surface treatment film, and galvanized steel sheet with surface treatment film

摘要

The present invention contains no chromium compound in the surface treatment film, heat discoloration resistance, heat crack resistance, flat plate corrosion resistance, corrosion resistance after alkaline degreasing, black resistance, stack black resistance, water stain resistance, solvent resistance, sweat resistance Provided is a surface treatment liquid for producing a zinc-plated steel sheet with a surface-treated film that is excellent in all of properties, paint adhesion, and storage stability. The surface treatment liquid for zinc-based plated steel sheet of the present invention has a silane coupling agent (A) having a glycidyl group, a tetraalkoxysilane (B), a zirconium carbonate compound (C), and a glass transition point (Tg) of 80 ° C. to 130 ° C. An anionic polyurethane resin (D), a vanadium compound (E), a molybdate compound (F), and water that are at 0 ° C. are added, the pH is 8.0 to 10.0, and the addition amount of each component is predetermined. It is characterized by satisfying the relationship.