Recycling of superabsorbent polymer with an extensional flow device

Patent metadata

Field	Value
Publication number	US-11746210-B2
Application number	US-202117341479-A
Country	US
Kind code	B2
Filing date	Jun 8, 2021
Priority date	Jun 16, 2020
Publication date	Sep 5, 2023
Grant date	Sep 5, 2023

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 PAA at an outlet of said extensional flow device; wherein said feed stream comprises water and 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; wherein said degradation of said SAP to said PAA requires a total energy of less than about 16 MJ/kg SAP; and wherein said PAA has a weight-average molecular weight less than about 1,000,000 g/mol.

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

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

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

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

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

7. 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.

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 4.

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 2.

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

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

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

13. The method of claim 1 , wherein said PAA is used to produce a recycled SAP; wherein said recycled SAP has a swelling ratio; and wherein said swelling ratio is 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

• C08J11/14 Primary

  by treatment with steam or water · CPC title

• C08F120/06

  Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof · CPC title

• C08J2333/02

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

• C08J11/16 Primary

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

• C08J11/105

  by treatment with enzymes · CPC title