| 摘要 |
PROBLEM TO BE SOLVED: To stably produce a polyester having reduced cloudiness and good hue by polycondensing terephthalic acid and ethylene glycol as main components in the presence of a polycondensation catalyst comprising antimony trioxide having specified or smaller lead and arsenic contents. SOLUTION: Antimony trioxide having a total content of lead and arsenic of 100 ppm or below is used. The polycondensation catalyst may be antimony trioxide alone or in combination with other polycondensation catalysts such as a germanium compound, a cobalt compound, or a tin compound. For example, a slurry of terephthalic acid and ethylene glycol is continuously fed into an esterification reactor in the presence of bis(β-hydroxyethyl) terephthalate and/or its oligomer, and esterified at 220-260 deg.C under 0.5-2.0 MPaG for 5-8 hr to obtain an esterfication product of a conversion of 90-95%, and this is polycondensed in the presence of the antimony trioxide at 260-280 deg.C under a pressure of 13 hPa or below.
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