To provide polyester in which crystallinity and tone are improved compared with conventional products by adding a specific phosphorus compound in a method of obtaining the polyester by conducting polycondensation in the presence of a titanium-based polycondensation catalyst.
The method of manufacturing polyester is characterized as follows. In a method in which terephthalic acid or an ester-forming derivative thereof, and ethylene glycol or an ester-forming derivative thereof are performed with polycondensation reaction in the presence of a polycondensation catalyst to manufacture polyester, a phosphorus compound of formula 1 is added to polyester that is obtained before beginning decompression in a polymerization reactor on a conversion basis of 0-50 ppm of a phosphorus atom, and 10-500 ppm of the phosphorus compound shown by the formula 1 is added to polyester that is obtained from beginning decompression in the polymerization reactor until when reaching to the targeted degree of polymerization, and in the obtained polyester, the temperature-rise crystallization temperature is at least 110°C and at most 155°C, and the temperature-fall crystallization temperature is at least 170°C and at most 220°C. In the formula 1, X denotes a hydroxyl group, a C1-20 hydrocarbon group, a C1-20 ester group, and a halogen family element.
HONDA KEISUKE
UCHIDA MINORU
