• Korean Chemical Engineering Research
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• v.51 no.1
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• pp.58-67
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• 2013

PBT (polybutylene terephthalate) has excellent mechanical properties such as low absorption, dimensional stability, abrasion resistance. It is used in manufacturing electronic components, the automobile part and the various precise parts. Bis (hydroxybutyl) terephthalate (BHBT) which is a PBT monomer, can be produced by transesterification reaction of DMT (dimethyl terephthalate) with 1,4-butandiol (BD). The kinetics of transesterification reaction of DMT with BD using zinc acetate as a catalyst was studied in a batch reactor. Previous kinetic studies was carried out in a semibatch reactor where generated methanol was removed so that reverse reactions were not considered in the kinetic expressions, resulting in inaccuracy of the kinetic model. Mathematical models of a batch reactor for the transesterification reaction were developed and used to characterize the reaction kinetics and the composition distribution of the reaction products. More accurate models than previous models was obtained and found to have a good agreement between model predictions and experimental data.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.103-111
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• 2018

Transesterification of BHET (Bis (2-Hydroxyethyl) Terephthalate), monomer of PET (Poly Ethylene Terephthalate) to BHBT (Bis (4-Hydroxybutyl Terephthate), monomer of PBT (Poly Butylene Terephthalate), using 1,4-BD (1,4-butanediol) were investigated. Zinc acetate was used as a catalyst for the reaction. Amounts of BHET, EG, and THF (Tetrahydrofuran) in a batch reactor were measured for determining the reaction kinetics. Mathematical models of the batch reactor for the transesterification reaction were developed and used to characterize the reaction kinetics and the composition distribution of the reaction products. Model predictions for the transesterification were in good agreement with experimental results.

• Korean Chemical Engineering Research
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• v.54 no.4
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• pp.437-442
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• 2016

A new route for PBT (Poly butylene terephthalate) production from recycled PET (Poly ethylene terephthalate) has been explored. The route consists of glycolysis of PET (Poly ethylene terephthalate) wastes using 1,4-butandiol into BHBT oligomers and polycondensation of the oligomers into PBT oligomer. This process uses post-consumer or post-industrial recycled PET and converts it into high-end PBT type engineering thermoplastic via a chemical recycling process. Zink acetate was used as a catalyst for both glycolysis and polycondensation. Two types of reactor for the glycolysis, batch and semi-batch reactor, were investigated and their performances were compared. Semi-batch reactor removes ethylene glycol (EG) and THF (tetrahydrofuran) during the reaction. Amounts of EG and THF generated during the glycolysis reaction were measured and used as criteria for the reactor performance. Performance of semi-batch reactor was shown to be better than that of batch reactor. Optimum reaction condition for the semi-batch reactor was BD/PET ratio of 4, and reaction temperature of $220^{\circ}C$, giving high EG yield (max 91%) and low production of THF. In addition, it was confirmed that the molecular weight of PBT oligomer increases in accordance with the progress of the polycondensation reaction.