| 摘要 |
A hydrophilic modification method comprising a step of forming a coat having a solid coat amount of 0.02 to 3 g/m2 on a heat exchanger with a modifier for hydrophilicity after treatment for rust prevention thereof wherein said modifier for hydrophilicity comprises a modified polyvinyl alcohol (A) having, on a side chain thereof, a group represented by the formula (I): in the formula, n represents an integer of 1 to 500, R1 represents a hydrogen atom or an alkyl group containing 1 to 4 carbon atoms, and R2 represents a hydrogen atom or a methyl group, and at least one member (B) selected from the group consisting of phosphorus compound salts and boron compound salts of Ca, Al, Mg, Fe and Zn, said group represented by the formula (I) accounting for 0.01 to 20 mole percent relative to hydroxyl and acetoxy groups contained in said modified polyvinyl alcohol.
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