Hydrophilic surface treating aqueous solution, hydrophilic surface treating method and hydrophilic surface treating film

A hydrophilic surface treating method, comprising the steps of

• degreasing a material to be treated made of an aluminum or aluminum alloy;
• and
• treating said material with a hydrophilic surface treating aqueous solution as defined as follows:
• (I) polyethylene oxide or ethylene oxide/propylene oxide copolymer containing polyoxyalkylene chain of 10 wt % or more in terms of solid content and having a weight average molecular weight of 10,000 to 2,000,000 in an amount of 10-78 parts by weight;
• (II) at least one member selected from the group consisting of polyvinyl alcohol, polyvinyl pyrrolidone and carboxyl methylcellulose in an amount of 10-78 parts by weight;
• (III) 10-70 parts by weight of N-methylol acrylamide;
• and
• (IV) at least one member selected from the group consisting of homopolymers of acrylic acid or methacrylic acid and copolymers of acrylic acid or methacrylic acid comprising at least one of said acids, in an amount of 2-70 parts by weight.