Method for purifying reclaimed polyethylene

Patent metadata

Field	Value
Publication number	US-10941269-B2
Application number	US-201916423226-A
Country	US
Kind code	B2
Filing date	May 28, 2019
Priority date	Jun 20, 2018
Publication date	Mar 9, 2021
Grant date	Mar 9, 2021

Abstract

A method for purifying a reclaimed polyethylene is disclosed. In one embodiment, the method involves obtaining reclaimed polyethylene, contacting the reclaimed polyethylene with a first fluid solvent to produce an extracted reclaimed polyethylene; then dissolving the extracted reclaimed polyethylene in a solvent to produce a first solution comprising polyethylene. The first solution is settled and then filtered. A purer polyethylene is separated from the resulting solution.

First claim

What is claimed is:

1. A method for purifying a reclaimed polyethylene comprising:
a. obtaining the reclaimed polyethylene wherein said reclaimed polyethylene is selected from the group consisting of post-consumer use polymers, post-industrial use polymers, and combinations thereof;
b. contacting the reclaimed polyethylene at a temperature from about 80° C. to about 280° C. and at a pressure from about 150 psig (1.03 MPa) to about 8,000 psig (55.16 MPa) with a first fluid solvent having a standard boiling point less than about 70° C., to produce an extracted reclaimed polyethylene;
c. dissolving the extracted reclaimed polyethylene in a solvent selected from the group consisting of the first fluid solvent, a second fluid solvent, and mixtures thereof, at a temperature from about 90° C. to about 280° C. and a pressure from about 200 psig (1.38 MPa) to about 8,000 psig (55.16 MPa) to produce a first solution comprising polyethylene, at least one dissolved contaminant, and at least one suspended contaminant;
d. settling said first solution comprising polyethylene, at least one dissolved contaminants, and at least one suspended contaminant at a temperature from about 90° C. to about 280° C. and at a pressure from about 200 psig (1.38 MPa) to about 8,000 psig (55.16 MPa) to produce a second solution comprising polyethylene, at least one dissolved contaminant, and less of the at least one suspended contaminant;
e. filtering said second solution at a temperature from about 90° C. to about 280° C. and at a pressure from about 200 psig (1.38 MPa) to about 8,000 psig (55.16 MPa) to produce a third solution comprising purer polyethylene, at least one dissolved contaminant, and even less of the at least one suspended contaminant; and
f. separating said purer polyethylene from said third solution; and
wherein said second fluid solvent has the same chemical composition or a different chemical composition as the first fluid solvent.

2. The method of claim 1 , wherein said purer polyethylene is separated from said third solution at a temperature from about 0° C. to about 280° C. and a pressure from about 0 psig (0 MPa) to 2,000 psig (13.79 MPa).

3. The method of claim 1 , wherein said reclaimed polyethylene is dissolved in the fluid solvent, or fluid solvent mixture, at a mass percent concentration of at least 0.5%.

4. The method of claim 1 , wherein said reclaimed polyethylene is post-consumer recycle derived polyethylene.

5. The method of claim 1 , wherein said reclaimed polyethylene is a polyethylene homopolymer or a primarily polyethylene copolymer.

6. The method of claim 1 , wherein said fluid solvent has a standard boiling point less than about 0° C. and greater than about −45° C. and a standard enthalpy change of vaporization of less than about +25 kJ/mol.

7. The method of claim 1 , wherein said fluid solvent is selected from the group consisting of olefinic hydrocarbons, aliphatic hydrocarbons, and mixtures thereof.

8. The method of claim 7 , wherein said aliphatic hydrocarbon is selected from the group consisting of C 1 -C 6 aliphatic hydrocarbons and mixtures thereof.

9. The method of claim 8 , wherein said aliphatic hydrocarbons and mixtures thereof is comprised of primarily C 4 aliphatic hydrocarbons.

10. The method of claim 1 , wherein said fluid solvent comprises C 4 liquefied petroleum gas.

11. The method of claim 1 , wherein said fluid solvent comprises n-butane, butane isomers, or mixtures thereof.

12. The method of claim 1 , wherein said fluid solvent comprises n-pentane, isomers of pentane, or mixtures thereof.

13. The method of claim 1 , wherein said temperature in the contacting, dissolving, settling and filtering steps is from about 110° C. to about 220° C.

14. The method of claim 1 , wherein said pressure in the contacting step is from about 400 psig (2.76 MPa) to about 2,400 psig (16.55 MPa).

15. A method for purifying a reclaimed polyethylene comprising:
a. obtaining the reclaimed polyethylene wherein said reclaimed polyethylene is selected from the group consisting of post-consumer use polymers, post-industrial use polymers, and combinations thereof;
b. contacting the reclaimed polyethylene at a temperature from about 80° C. to about 280° C. and at a pressure from about 150 psig (1.03 MPa) to about 8,000 psig (55.16 MPa) with a first fluid solvent having a standard boiling point less than about 70° C., to produce an extracted reclaimed polyethylene;
c. dissolving the extracted reclaimed polyethylene in a solvent selected from the group consisting of the first fluid solvent, a second fluid solvent, and mixtures thereof, at a temperature from about 90° C. to about 280° C. and a pressure from about 200 psig (1.38 MPa) to about 8,000 psig (55.16 MPa) to produce a first solution comprising polyethylene, at least one dissolved contaminant, and at least one suspended contaminant;
d. settling said first solution comprising polyethylene, at least one dissolved contaminants, and at least one suspended contaminant at a temperature from about 90° C. to about 280° C. and at a pressure from about 200 psig (1.38 MPa) to about 8,000 psig (55.16 MPa) to produce a second solution comprising polyethylene, at least one dissolved contaminant, and less of the at least one suspended contaminant;
e. filtering said second solution at a temperature from about 90° C. to about 280° C. and at a pressure from about 200 psig (1.38 MPa) to about 8,000 psig (55.16 MPa) to produce a third solution comprising purer polyethylene, at least one dissolved contaminant, and even less of the at least one suspended contaminant; and
f. purifying by further filtering said third solution at a temperature from about 90° C. to about 280° C. and at a pressure from about 200 psig (1.38 MPa) to about 8,000 psig (55.16 MPa) by contacting said third solution with one or more solid media to produce a fourth solution comprising purer polyethylene; and
g. separating said purer polyethylene from said fourth solution; and
wherein said second fluid solvent has the same chemical composition or a different chemical composition as the first fluid solvent.

16. The method of claim 15 , wherein said purer polyethylene is separated from said forth solution at a temperature from about 0° C. to about 280° C. and a pressure from about 0 psig (0 MPa) to 2,000 psig (13.79 MPa).

17. The method of claim 15 , wherein said reclaimed polyethylene is dissolved in the fluid solvent, or fluid solvent mixture, at a mass percent concentration of at least 0.5%.

18. The method of claim 15 , wherein said reclaimed polyethylene is post-consumer recycle derived polyethylene.

19. The method of claim 15 , wherein said reclaimed polyethylene is a polyethylene homopolymer or a primarily polyethylene copolymer.

20. The method of claim 15 , wherein said fluid solvent has a standard boiling point less than about 0° C. and greater than about −45° C. and a standard enthalpy change of vaporization of less than about +25 kJ/mol.

Assignees

• Procter & Gamble

Inventors

• Layman John Moncrief
• Collias Dimitris Ioannis
• Schonemann Hans
• Williams Kara

Classifications

• Y02W30/62

  Plastics recycling; Rubber recycling · CPC title

• C08J11/08 Primary

  using selective solvents for polymer components · CPC title

• B29B17/00 Primary

  Recovery of plastics or other constituents of waste material containing plastics; ({volume reduction of waste plastics, e.g. by mechanical compacting or melting disposal of solid waste B09B;} chemical recovery C08J11/00) · CPC title

• C08J2323/06

  Polyethene · CPC title

• B29K2023/06

  PE, i.e. polyethylene · CPC title