WATER-BASE BINDER FOR ALUMINUM MATERIAL BRAZING, BRAZING COMPOSITION, AND METHOD OF BRAZING WITH THE COMPOSITION

摘要

A water-base binder for use in brazing in producing brazed aluminum products such as radiators for engines and condensers for car air conditioners. The water-base binder is obtained by saponifying a methacrylate polymer having an acid value and a glass transition temperature respectively in specific ranges and combines solubility in water with volatility. A brazing composition obtained by mixing the binder with a flux, etc. in the presence of an alcohol having a flash point not lower than a specific temperature has no fear of taking fire or exploding. It further has so high wetting ability that it can be evenly applied to an aluminum material. The use of a binder obtained by adding polyoxirane or polyoxazoline as a minor ingredient to the methacrylate polymer as the main ingredient enables the brazing composition to have improved ordinary-temperature tight adhesion to aluminum materials and to be prevented from suffering a viscosity increase during application or storage.