Surface treatment composition for coated steel sheet, surface treated plated steel sheet and method of production of same, and coated plated steel sheet and method of production of same

摘要

An aqueous surface treatment composition for coated steel sheet securing sufficient working adhesion while causing the formation of a surface treatment layer imparting excellent overhang corrosion resistance even without containing chrome, that is, a surface treatment composition containing a specific organic silicon compound, hexafluorometallic acid, a urethane resin having specific cationic groups, a vanadium compound, and an aqueous medium and sufficiently securing working adhesion while imparting excellent overhang corrosion resistance by the urethane resin having cationic groups and a total amine value of specific values is provided.