METHOD OF PRODUCING POLYBUTYLENETEREPHTHALATE

摘要

PROBLEM TO BE SOLVED: To provide a method of producing polybutyleneterephthalate(PBT) stably in which high content of THF can be obtained by distilling a distillate from an esterification reactor using a distillation column with less number of theoretical plate and at a small reflux ratio. SOLUTION: This method of producing PBT comprises the steps of reacting a dicarboxylic acid component in which terephthalic acid is dominating with a diol component in excess amount to the dicarboxylic acid component in which 1,4-butanediol is dominating in an esterification reactor in the presence of an esterification reaction catalyst comprising a titanium compound, where esterification reaction takes place while distilling a distillate comprising mainly byproduct THF and water from the top of a distillation column equipped on the esterification reactor, followed by polycondensation reaction in a polycondensation reactor to obtain PBT, where the content of primary alcohol having less than 4 carbons contained in the distillate is regulated to be 40 wt.% or less to that of THF in the distillate.