Feedstock engineering of polyester waste for recycling processes

Patent metadata

Field	Value
Publication number	US-11807725-B2
Application number	US-202117540184-A
Country	US
Kind code	B2
Filing date	Dec 1, 2021
Priority date	Dec 2, 2020
Publication date	Nov 7, 2023
Grant date	Nov 7, 2023

Abstract

A waste polyester material is prepared for recycling by dissolving the material in a solution comprising hexafluoroisopropyl (HFIPA) and a chlorinated hydrocarbon, such as dichloromethane (DCM) and/or an aromatic hydrocarbon, such as toluene or xylene, to form a dissolved polyester sample. The dissolved polyester may be prepared for recycling by evaporation, spray drying, and/or precipitation, which produces a purified solid polyester product. The dissolution solution, which is separated from the purified solid polyester product, is also recycled through distillation with purification.

First claim

We claim:

1. A method comprising:
treating a waste material comprising a polyester with a dissolution solution comprising hexafluoroisopropyl alcohol and a chlorinated hydrocarbon and/or an aromatic hydrocarbon to form dissolved polyester;
purifying the dissolved polyester; and
treating the purified and dissolved polyester with a technique to produce solid polyester, wherein the dissolution solution is separated from the solid polyester.

2. The method of claim 1 , wherein the chlorinated hydrocarbon is dichloromethane.

3. The method of claim 1 , wherein the aromatic hydrocarbon is toluene and/or xylene.

4. The method of claim 1 , wherein the dissolution solution comprises 30% hexafluoroisopropyl alcohol and 70% dichloromethane.

5. The method of claim 1 , wherein the dissolution solution comprises 1-85% dichloromethane.

6. The method of claim 1 , wherein the separated dissolution solution is recovered for reuse by distillation and/or condensation.

7. The method of claim 1 , wherein the dissolved polyester is purified by decolorization and/or deionization.

8. The method of claim 1 , wherein the dissolved polyester is purified with a treatment selected from the group consisting of activated carbon, ion exchange, filtration, and combinations thereof.

9. The method of claim 1 , wherein the technique to produce the solid polyester is selected from the group consisting of evaporation, spray drying, precipitation, and combinations thereof.

10. The method of claim 1 , wherein the solid polyester is recycled by a chemical or mechanical recycling process.

11. The method of claim 10 , wherein the chemical recycling process is selected from the group consisting of alcoholysis, hydrolysis, acidolysis, phosphorolysis, aminolysis, ammonolysis, and enzymolysis.

12. The method of claim 10 , wherein the chemical recycling process is glycolysis depolymerization.

13. The method of claim 1 , wherein prior to treatment with the dissolution solution, the waste polyester is separately pre-treated with a polyester non-solvent to remove impurities from the waste polyester.

14. The method of claim 13 , wherein the polyester non-solvent is selected from the group consisting of chlorinated hydrocarbons, aromatic hydrocarbons, and combinations thereof.

15. The method of claim 13 , wherein the polyester non-solvent is selected from the group consisting of dichloromethane, toluene, xylene, and combinations thereof.

16. A method comprising:
treating a waste material comprising polyethylene terephthalate (PET) with a dissolution solution comprising 30% hexafluoroisopropyl alcohol and 70% dichloromethane to form dissolved PET;
purifying the dissolved PET; and
treating the purified and dissolved PET with a technique to produce solid PET for reuse, wherein the dissolution solution is separated from the solid PET.

17. The method of claim 16 , wherein the separated dissolution solution is recovered for reuse by distillation and/or condensation.

18. The method of claim 16 , wherein the dissolved PET is purified by decolorization and/or deionization.

19. The method of claim 16 , wherein the dissolved PET is purified with a treatment selected from the group consisting of activated carbon, ion exchange, filtration, and combinations thereof.

20. The method of claim 16 , wherein the technique to produce the solid PET is selected from the group consisting of evaporation, spray drying, precipitation, and combinations thereof.

21. The method of claim 16 , wherein the solid PET is recycled by a chemical or mechanical recycling process.

22. The method of claim 21 , wherein the chemical recycling process is selected from the group consisting of alcoholysis, hydrolysis, acidolysis, phosphorolysis, aminolysis, ammonolysis, and enzymolysis.

23. The method of claim 21 , wherein the chemical recycling process is glycolysis depolymerization.

24. The method of claim 16 , wherein prior to treatment with the dissolution solution, the waste material is separately pre-treated with dichloromethane to remove impurities from the waste sample.

25. The method of claim 16 , wherein the waste material is colored, dirty, and/or mixed PET flake.

26. The method of claim 16 , wherein the waste material comprises a colored PET fabric and/or fiber.

Assignees

• IBM

Inventors

• Breyta Gregory
• Allen Robert David
• Parekh Nitin Shashikant

Classifications

• C08J11/20 Primary

  by treatment with hydrocarbons or halogenated hydrocarbons · CPC title

• C08J2367/02

  Polyesters derived from dicarboxylic acids and dihydroxy compounds; (C08J2367/06 takes precedence) · CPC title

• C08J11/08 Primary

  using selective solvents for polymer components · CPC title

• C08J11/24

  containing hydroxyl groups · CPC title

• B29B17/02

  Separating plastics from other materials · CPC title