Nippon Paint Surf Chemicals Co., Ltd.

Junsuke Hokka

Yuko Wada

Norizumi Matsui

Akihiro Mizuno

A chemical conversion agent which is capable of providing, for example, an aluminum-based metal material with excellent corrosion resistance and moisture resistance, while also providing the aluminum-based metal material with excellent adhesion with a laminate film, excellent hydrofluoric acid resistance, and excellent alkali resistance. The chemical conversion agent has (1) a mass concentration of zirconium of 5-5,000 ppm by mass; (2) a mass concentration of titanium is 5-5,000 ppm by mass; (3) a mass concentration of vanadium is 10-1,000 ppm by mass; (4) a mass concentration of a metal stabilizer is 5-5,000 ppm by mass; and (5) the pH is 2-6.

Chemical conversion agent and chemical conversion coating film

A surface treatment method capable of imparting exceptional corrosion resistance and moisture resistance to an NB heat exchanger. The method includes subjecting an NB heat exchanger to a chemical conversion treatment to form a chemical conversion film on the surface thereof using a chemical conversion treatment agent that contains zirconium and/or titanium in a total amount of 5-5,000 ppm by weight, vanadium in an amount of 10-1,000 ppm by weight, and has a pH of 2-6; bringing the NB heat exchanger on whose surface the chemical conversion film is formed into contact with a hydrophilization agent containing a hydrophilic resin and a guanidine compound and/or a salt thereof; and baking the NB heat exchanger subjected to the contacting process, whereby a hydrophilic film is formed on the surface thereof.

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Tokyo, Japan

Junsuke Hokka