Preparation of low-acid polyalkylene terephthalate and preparation of macrocyclic polyester oligomer therefrom
AssigneeCyclics Corporation
InventorsPeter D. Phelps, Gary R. Faler
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Abstract
The invention provides methods and systems for manufacturing low-acid polyalkylene terephthalate, for example, polybutylene terephthalate (PBT). The invention also provides methods and systems for preparing macrocyclic polyester oligomer (MPO) from low-acid polyalkylene terephthalate. Finally, the invention provides methods and systems for preparing MPO via reaction of a diol and a dialkyl ester in an organic solvent to form non-isolated, low-acid polyalkylene terephthalate which undergoes cyclization (depolymerization) to form MPO.
Claims16
A polybutylene terephthalate polymer having an acid concentration less than 7 meq/kg.
A method for preparing a low-acid polybutylene terephthalate product, the method comprising the step of exposing a mixture to a temperature no greater than about 240° C. and at a pressure no less than about atmospheric pressure, the mixture comprising:
- (a) bishydroxylbutyl terephthalate;
- (b) an organic solvent;
- and
- (c) a catalyst.
Dependencies are inferred from the claim text.