Recycling of superabsorbent polymer with an extensional flow device

Patent metadata

Field	Value
Publication number	US-11525047-B2
Application number	US-202016999127-A
Country	US
Kind code	B2
Filing date	Aug 21, 2020
Priority date	Aug 23, 2019
Publication date	Dec 13, 2022
Grant date	Dec 13, 2022

Abstract

Poly(acrylic acid)-based superabsorbent polymer (SAP) in a feed stream is converted into poly(acrylic acid) (PAA) in an extensional flow device. The total energy used to degrade the SAP into PAA is less than about 50 MJ/kg SAP.

First claim

What is claimed is:

1. A method for degrading a superabsorbent polymer (SAP) to poly(acrylic acid) (PAA) comprising flowing a feed stream comprising said SAP into an inlet of an extensional flow device and producing a product stream comprising said PAA at an outlet of said extensional flow device; wherein said feed stream comprises said SAP at a concentration greater than about 1 wt %; wherein said feed stream has a residence time in said extensional flow device of less than about 120 s; and wherein said degradation of said SAP to said PAA requires a total energy of less than about 50 MJ/kg SAP.

2. The method of claim 1 , wherein said residence time is less than about 60 s.

3. The method of claim 1 , wherein said total energy is less than about 16 MJ/kg SAP.

4. The method of claim 1 , wherein said feed stream comprises SAP and water.

5. The method of claim 1 , wherein said feed stream comprises SAP and hydrogen peroxide.

6. The method of claim 1 , wherein said SAP has degree of neutralization (DN) greater than about 50%.

7. The method of claim 1 , wherein said SAP has DN between about 65% and about 75%.

8. The method of claim 1 , wherein said feed stream has a viscosity; wherein said product stream has a viscosity; wherein the ratio of the viscosity of the product stream to the viscosity of the feed stream is the viscosity ratio; and wherein the negative logarithm of said viscosity ratio is less than about 6.

9. The method of claim 1 , wherein said feed stream has a viscosity; wherein said product stream has a viscosity; wherein the ratio of the viscosity of the product stream to the viscosity of the feed stream is the viscosity ratio; and wherein the negative logarithm of said viscosity ratio is less than about 4.

10. The method of claim 1 , wherein said feed stream has a viscosity; wherein said product stream has a viscosity; wherein the ratio of the viscosity of the product stream to the viscosity of the feed stream is the viscosity ratio; and wherein the negative logarithm of said viscosity ratio is less than about 2.

11. The method of claim 1 , wherein said PAA has a weight-average molecular weight less than about 2,000,000 g/mol.

12. The method of claim 1 , wherein said PAA has a weight-average molecular weight less than about 1,000,000 g/mol.

13. The method of claim 1 , wherein said PAA has a polydispersity index (PDI) less than about 4.

14. The method of claim 1 , wherein said PAA is used to produce a recycled SAP; said SAP comprises PAA at a concentration is less than about 30%.

15. The method of claim 1 , wherein said PAA is used to produce a recycled SAP; wherein said recycled SAP has an amount of extractables less than about 15%.

16. The method of claim 1 , wherein said PAA is used to produce a recycled SAP; wherein said recycled SAP has a swelling ratio greater than about 45 g/g.

Assignees

• Procter & Gamble

Inventors

• Collias Dimitris Ioannis
• Mcdaniel John Andrew
• Gilbertson Gary Wayne
• James Martin Ian
• Simonyan Arsen Arsenov

Classifications

• Y02W30/62

  Plastics recycling; Rubber recycling · CPC title

• C08J11/16 Primary

  by treatment with inorganic material (C08J11/14 takes precedence) · CPC title

• C08J2335/02

  Characterised by the use of homopolymers or copolymers of esters (C08J2335/06, C08J2335/08 take precedence) · CPC title

• C08J2333/02

  Homopolymers or copolymers of acids; Metal or ammonium salts thereof · CPC title

• C08J2300/14

  Water soluble or water swellable polymers, e.g. aqueous gels · CPC title