| 摘要 |
PURPOSE: To obtain a highly concentrated aqueous polyester dispersion by kneading a water-dispersible polyester having a small amount of sulfonic acid (metal salt) groups (bonded especially to the aromatic nucleus of a dicarboxylic acid) and water to form a homogenous translucent product and diluting the product with water. CONSTITUTION: While water is being added to a water-dispersible polyester resin having sulfonic acid (metal salt) groups, they are kneaded until the phase inversion point (at which the product becomes translucent) is passed. The product is further diluted with water to prepare an aqueous polyester resin dispersion. Although the sulfonated polyester can be synthesized by various methods, it is advantageous to adopt a method comprising reacting a sulfonated polycarboxylic acid such as the one obtained by sulfonating an aromatic polycarboxylic acid such as phthalic anhydride with a polycarboxylic acid and a polyol. It is essential that at least 40mol% wholly aromatic dicarboxylic acid is used, and 0.2-0.6 meq/gr of sulfonic acid groups are introduced thereto. The obtained aqueous polyester resin dispersion is a microdispersion which can give a coating film excellent in water resistance. |
