SURFACE TREATMENT AGENT, METHOD FOR PRODUCING ALUMINUM ALLOY MATERIAL FOR CANS, SAID ALUMINUM ALLOY MATERIAL HAVING SURFACE-TREATED COATING FILM, AND ALUMINUM ALLOY CAN BODY AND CAN LID USING SAME

摘要

The present invention addresses the problem of providing a surface treatment agent that is capable of forming a surface-treated coating film, which has excellent corrosion resistance and adhesion, in or on the surface of an aluminum alloy material for cans. The present invention solves the above-described problem by a surface treatment agent which is used for a surface treatment of an aluminum alloy material for cans, and which contains zirconium, aluminum, nitric acid radicals and fluorine, while having a pH within the range of 2.0-4.0, a mass molarity of the zirconium within the range of from 3.2 mmol/kg to 33.0 mmol/kg, a mass molarity of the aluminum within the range of from 14.8 mmol/kg to 74.1 mmol/kg, a mass molarity of the nitric acid radicals within the range of from 16.1 mmol/kg to 161.4 mmol/kg, and a mass molarity of the fluorine within the range of from 52.6 mmol/kg to 526.3 mmol/kg. This surface treatment agent satisfies (F - 6Zr)/Al ≥ 2.5 (wherein F represents the mass molarity of the fluorine, Zr represents the mass molarity of the zirconium and Al represents the mass molarity of the aluminum), and does not substantially contain a phosphorus compound.