| abstract |
A method for surface treating a heat exchanger, a hydrophilizing treatment agent used in this method, and an aluminum heat exchanger obtained from this method are provided that excel in the initial adherence, hydrophilicity, and odor suppressibility, and can maintain these abilities for an extended time, while having little burden on the environment and the human body. The method for surface treating an aluminum heat exchanger that is brazed includes (1) a pickling treatment step; (2) a chemical conversion treatment step; and (3) a hydrophilization treatment step, in which the acidic cleaning agent contains nitric acid and sulfuric acid and contains ferric salt in a predetermined amount, the hydrophilizing treatment agent contains silica grains coated with a vinyl alcohol polymer and a polyallylamine resin. |