| abstract |
(57) [Problem] To provide a method for hydrophilizing a heat exchanger and a heat exchanger subjected to hydrophilization, which can maintain deodorant properties and hydrophilicity even after long-term use. SOLUTION: After performing a pickling treatment on a heat exchanger in advance, Chromic acid chromating agent, phosphoric acid chromating agent, Alternatively, a chemical conversion treatment for forming a chemical conversion film with a zirconium-based treating agent is performed, and thereafter, the aqueous medium contains silica fine particles and a vinyl alcohol-based polymer, and the mass ratio of the silica fine particles to the vinyl alcohol-based polymer is 30: 70 A hydrophilizing agent having a total content of 1 to 25% by mass, wherein the silica fine particles are coated with the vinyl alcohol-based polymer and have an average particle diameter of 5 to 10 Using a hydrophilizing agent dispersed in an aqueous medium in the form of 00 nm coated particles, the coating amount is 0.1 to 3 g / m 2. The hydrophilic treatment is performed so that |