| 摘要 |
PURPOSE:To obtain a high-melting point polyester while suppressing its pyrolysis, by polycondensation at such temperatures as to be lower than the melting point of the resulting polyester in the presence of a liquid substance which is non-volatile and stable under said polycondensation condition. CONSTITUTION:(A) A dicarboxylic acid component, >=70mol% of which represents a single aromatic dicarboxylic acid (e.g., terephthalic acid) and (B) a diol component, >=70mol% of which represents a single component (e.g., ethyl ene glycol) are brought to polycondensation at temperatures lower than the melting point of the resulting polyester (e.g., >=200 deg.C) in the presence of (C) such a non-volatile liquid substance as not to be distilled out as much as at least a half within 1hr when placed at the polycondensation temperature and pressure (e.g., polyethylene with a melt viscosity falling between 10 and 10,000 poises) (e.g., in such an amount of 10-900pts.wt. per 100pts.wt. of the final polyester) followed by separation of the component (C) by, for example, filtra tion, thus obtaining the objective polyester.
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