Abstract: An aluminum-containing metal material for, for example, a heat-exchanger for motorcars is surface-treated by chemically etching an Al-containing metal material surface, forming a first protective layer on the etched surface by a chemical conversion treatment with an aqueous solution of Zr phosphate or Ti phosphate, and coating the first protective layer with a second protective layer containing a hydrophilic resin including non-cross-linked hydrophilic functional groups and at least partially cross-linked reactive functional groups different from the hydrophilic functional groups, to impart high hydrophilicity and resistance to odor generation and corrosion to the aluminum-containing metal material surface.

Abstract: A hydrophilic coating having excellent hydrophilicity, which can prevent offensive odor generation, and which has a good antibacterial performance and formability, is formed on an aluminum-containing metal material by coating an aqueous hydrophilization treating liquid containing (A) a glycidyl group-containing, water-soluble organic compound; (B) a water-soluble polymeric or polymerizable compound having a tert-amino group and at least one hydrophilic functional group selected from sulfonic, phosphonic, carboxyl, polyalkyleneglycol, hydroxyl and amide groups; and (C) an antibacterial agent not decomposing at 100° C. or lower, on an aluminum-containing metal material; and heat-drying the coated liquid.