PROCESS FOR PRODUCING POLYBUTYLENE TEREPHTHALATE RESIN, AND POLYBUTYLENE TEREPHTHALATE RESIN THEREBY OBTAINED

摘要

PROBLEM TO BE SOLVED: To provide a process for producing a PBT resin having less fish eyes, and to obtain a PBT resin obtained by the process. SOLUTION: The process for continuously producing a PBT resin comprises subjecting a lower alkyl ester of terephthalic acid and 1,4-butane diol to transesterification in the presence of a transesterification catalyst in one or more transesterification reactors, subjecting the transesterified compounds to polycondensation in one or more polycondensation reactors, and withdrawing the obtained polymer from a polymer withdrawing die, wherein a filter is installed in the reaction product flow path between the outlet of the first transesterification reactor and the outlet of the polymer withdrawing die to pass the reaction product through the filter. The PBT resin obtained by the process gives a film having at most 10 fish eyes with a core of 20μm or larger per 100 cm2.