PROCESSES FOR PREPARING LOW-ACID POLYALKYLENE TEREPHTHALATE FROM DIOL-CAPPED PRE-POLYMER AND LINEAR OLIGOMER RECYCLATE AND USING SUCH IN THE PRODUCTION OF MACROCYCLIC POLYESTER OLIGOMER

摘要

The invention relates to a method for producing low-acid polyalkylene terephthalate from which MPO can be advantageously manufactured. In certain embodiments, low-acid polybutylene terephthalate (PBT) is prepared by reacting low molecular weight, diol-stopped PBT pre-polymer with a linear oligomer recyclate in refluxing ortho-dichlorobenzene (oDCB) solvent. The linear oligomer recyclate may be a by-product of the depolymerization/ cyclization of the low-acid PBT, thereby synergistically increasing overall conversion of reactants to the MPO product, cyclic polybutylene terephthalate (cPBT).