Method and device for purifying polybutylene terephthalate

Patent metadata

Field	Value
Publication number	US-10508177-B2
Application number	US-201715802445-A
Country	US
Kind code	B2
Filing date	Nov 2, 2017
Priority date	Jun 26, 2017
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

A method for purifying polybutylene terephthalate (PBT) includes: providing or receiving initial PBT, in which oligomers and tetrahydrofuran are present; dissolving the initial PBT in hexafluoroisopropanol (HFIP) to form a solution, in which the oligomers are also dissolved in the HFIP; and contacting the solution with compressed CO2 at a temperature and a pressure, thereby precipitating the purified PBT, resulting from a large portion of the oligomers are still dissolved in the HFIP, in the operation the temperature is in a range of 20° C. to 35° C., and the pressure is in a range of 900 psi to 1400 psi. A device for purifying PBT is also provided.

First claim

What is claimed is:

1. A method for purifying polybutylene terephthalate (PBT), comprising:
providing or receiving initial PBT, wherein the initial PBT comprises oligomers;
dissolving the initial PBT in hexafluoroisopropanol (HFIP) to form a PBT/HFIP solution, wherein the oligomers are dissolved in the HFIP, wherein a weight percent of the initial PBT in the PBT/HFIP solution is in a range of about 1 wt % to about 8 wt %; and
contacting the PBT/HFIP solution with compressed carbon dioxide (CO 2 ) at a temperature of 20° C. to 35° C. and a pressure of 900 psi to 1400 psi, thereby precipitating purified PBT at the temperature and the pressure, wherein at least a portion of the oligomers are still dissolved in the HFIP.

2. The method of claim 1 , wherein contacting the PBT/HFIP solution with the compressed CO 2 comprises:
allowing the PBT/HFIP solution to form a plurality of droplets in the compressed CO 2 .

3. The method of claim 1 , wherein contacting the PBT/HFIP solution with the compressed CO 2 comprises:
precipitating a plurality of PBT particles, and each of the PBT particles having an average particle diameter in a range of about 0.1 microns to about 0.4 microns.

4. The method of claim 1 , wherein contacting the PBT/HFIP solution with the compressed CO 2 at the temperature and the pressure comprises:
introducing the PBT/HFIP solution into a high-pressure precipitation tank containing the compressed CO 2 .

5. The method of claim 1 , further comprising:
drying the purified PBT using supercritical CO 2 .

6. The method of claim 1 , wherein the temperature is in a range of 22° C. to 26° C.

7. The method of claim 1 , wherein the pressure is in a range of 1100 psi to 1300 psi.

8. The method of claim 1 , wherein a weight percent of the initial PBT in the PBT/HFIP solution is in a range of 3 wt % to 6 wt %.

Assignees

• Univ Nat Tsing Hua
• Chang Chun Plastics Co Ltd
• Chang Chun Petrochemical Co Ltd

Inventors

• Tan Chung-Sung

Classifications

• B01D11/0484

  Controlling means · CPC title

• C08G63/90

  Purification; Drying · CPC title

• C08G63/127

  Acids containing aromatic rings · CPC title

• C08J3/14 Primary

  by precipitation from solutions {(C08J3/122 takes precedence)} · CPC title

• C08G63/183

  Terephthalic acids · CPC title