| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a polyester; wherein a cyclic dimer content is reduced, a molded item has excellent heat stability when a molded item, such as a fiber, a film, a sheet, etc. is molded, no practical problem is caused by surface precipitates due to the cyclic dimer, little drawbacks are caused by the cyclic dimer in a post-processing or an application field, and the method is economical. SOLUTION: In the method for producing a polyester having: an esterification process of obtaining an esterification reaction product by performing an esterification reaction and/or a transesterification reaction using an aliphatic dicarboxylic acid and/or an alkyl ester thereof, and an aliphatic diol as major raw materials; and a polycondensation process of obtaining the polyester by continuously performing a polycondensation reaction of the esterification reaction product in a molten state using a plurality of steps of continuous polycondensation reaction vessels, a ratio of the total amount of terminal carboxyl groups to the total amount of terminal groups of the polycondensation reaction product supplied to the polycondensation reaction vessel at the final step of the polycondensation process, [the amount of the terminal carboxyl groups (Eq/t)/the amount of the terminal groups (Eq/t)=R] is set to 0.15 or more. COPYRIGHT: (C)2010,JPO&INPIT
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