Manufacturing method of poly(trimethylene terephthalate)

Abstract

This invention provides a method for manufacturing polyethylene terephthalate (PET), comprising the following steps: providing a recycled polyester material, wherein the recycled polyester material includes PET; subjecting the recycled polyester material to a depolymerization reaction with ethylene glycol; subjecting the product obtained from the depolymerization reaction to a transesterification reaction with propylene glycol; subjecting the product obtained from the transesterification reaction to a polymerization reaction, wherein the product obtained from the polymerization reaction includes PET, and the content of PET is less than 10% by weight based on the total weight of the product obtained from the polymerization reaction.

Claims

1. A method for manufacturing polypropylene terephthalate, comprising: The method provides a recycled polyester material comprising polyethylene terephthalate (PET); depolymerizes the recycled polyester material with ethylene glycol; transesterifies the product obtained from the depolymerization reaction with propylene glycol, wherein the product obtained from the depolymerization reaction comprises bis(2-hydroxyethyl) terephthalate; and polymerizes the product obtained from the transesterification reaction, wherein the product obtained from the polymerization reaction comprises polyethylene terephthalate (PET), and the PET content is less than 10% by weight based on the total weight of the product obtained from the polymerization reaction.

2. The manufacturing method as claimed in claim 1, wherein the molar ratio of bis(2-hydroxyethyl) terephthalate to 1,3-propanediol is 1:1 to 1:

5.

3. The manufacturing method as claimed in claim 1, wherein the product obtained by the transesterification reaction includes bis(2-hydroxypropyl) terephthalate.

4. The manufacturing method as claimed in claim 1, wherein the catalyst used in the transesterification reaction and the polymerization reaction each comprises a titanium catalyst.

5. The manufacturing method as claimed in claim 4, wherein the titanium content in the titanium catalyst is from 25 ppm to 100 ppm.

6. The manufacturing method as claimed in claim 4, wherein the catalyst used for the transesterification reaction and the catalyst used for the polymerization reaction are the same.

7. The manufacturing method as claimed in claim 1, wherein the content of polypropylene terephthalate is 90% by weight or more, based on the total weight of the products obtained from the polymerization reaction.

8. The manufacturing method as claimed in claim 1, wherein the intrinsic viscosity of the product obtained by the polymerization reaction is 0.76 to 0.85 dL / g, and the product obtained by the polymerization reaction has an L value of 60 or higher and a b value of 20 or lower as defined in the CIE Lab color space.

9. The manufacturing method as claimed in claim 1, wherein the recycled polyester materials include recycled PET bottle flakes and recycled polyester fabrics.

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