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.
本发明提供了一种用于涂覆钢板的
水性表面处理组合物,该组合物既能确保充分的工作附着力,又能形成表面处理层,即使不含
铬也能赋予其优异的抗悬挂腐蚀性能,即含有特定
有机硅化合物、六
氟甲基酸、具有特定阳离子基团的聚
氨酯
树脂、
钒化合物和
水性介质的表面处理组合物,并通过具有阳离子基团和特定值总胺的聚
氨酯
树脂充分确保工作附着力,同时赋予其优异的抗悬挂腐蚀性能。