| 摘要 |
PURPOSE:To obtain stably a crosslinked polyester resin of any desired degree of crosslinking, by esterifying a polycarboxylic acid component with a diol component and crosslinking the product while increasing the pressure in the reaction system with an increasing viscosity. CONSTITUTION:In an operation of esterifying or transesterifying a polycarboxylic acid component comprising 2-100mol%, based on the total carboxylic acid component, tricarboxylic acid component (a) and at most 98mol%, based on the total carboxylic acid component, dicarboxylic acid compo nent (b) with a diol component (c) in an amount represented by the formula and forming crosslinkages while distilling the diol component (c) in a vacuum <=150mmHg, the rate of crosslinking is controlled by increasing the pressure in the reaction system with he increasing viscosity of the polymer. Although the rate of removal of the diol component (c) by distillation depends on the pressure and temperature in the reaction system, the degree of vacuum is prefer ably 150mmHg or below in consideration of the pressure conditions for stopping the reaction system.
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