Surface-treated steel sheet, process for producing the same and resin-coated surface-treated steel sheet

A process for producing a surface-treated steel sheet for cans by forming, on a steel sheet, a coating of a compound comprising chiefly Zr and containing F, the process including the steps of:

• forming the coating that contains Zr in an amount of 80 to 200 mg/m2 by the cathodic electrolysis in an aqueous solution that contains Zr ions and F ions;
• and
• adjusting the surface by bringing an alkaline aqueous solution into contact with the coating on the surface that becomes the inner surface side of the can and by bringing warm water into contact with the coating on the surface that becomes the outer surface side of the can.