# US 11,993,684 B2 · Recycling of superabsorbent polymer with a hybrid oxidative degradation and high shear mixing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,993,684 B2 - Document ID: US11993684B2 - Status: Granted - Kind: B2 - Application number: 17/678,707 - Filed: 2022-02-23 - Published: 2022-08-25 - Granted: 2024-05-28 - Earliest claimed: 2021-02-23 - Assignees: The Procter & Gamble Company - Applicants: The Procter & Gamble Company - Inventors: Dimitris Ioannis Collias; Gary Wayne Gilbertson; Martin Ian James; Morgan Christine McGrath; Raul Victorino Nunes; Heitham Darrell Safi; Arsen Arsenov Simonyan; John Christopher Wesner - Web page: https://patentgrep.com/patent/US11993684B2 ## CPC - C08J 11/16: by treatment with inorganic material (C08J11/14 takes precedence) - C08J 2333/02: Homopolymers or copolymers of acids; Metal or ammonium salts thereof - C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29) ## Abstract New process for recycling of poly(acrylic acid)-based superabsorbent polymer (SAP) using a synergistic combination of high shear mixing device and oxidative degradation of SAP to produce poly(acrylic acid) (PAA) useful to recycle pre- and post-consumer SAP. ## Claims ### Claim 1 A process for degrading acrylic acid based superabsorbent polymer (SAP) to poly(acrylic acid) PAA comprising: a. Forming a solution, wherein the solution comprises an oxidizer soluble salt in water at a dissolution temperature and a dissolution concentration; b. Dispersing SAP into the solution, forming an SAP dispersion, using a mixer with power input NP/M greater than about 20 W/kg solution; and c. Reacting said oxidizer with said SAP at a reaction temperature and for a reaction time to produce a PAA solution. ### Claim 2 (depends on 1) The process according to claim 1 wherein said reaction time is from about 10 min to about 240 min. ### Claim 3 (depends on 1) The process according to claim 1 wherein said reaction time is from about 10 min to about 180 min. ### Claim 4 (depends on 1) The process according to claim 1 wherein said reaction time is from about 10 min to about 90 min. ### Claim 5 (depends on 1) The process according to claim 1 wherein said reaction temperature is from about 60° C. to about 120° C. ### Claim 6 (depends on 1) The process according to claim 1 wherein said reaction temperature is from about 70° C. to about 110° C. ### Claim 7 (depends on 1) The process according to claim 1 wherein said reaction temperature is from about 70° C. to about 90° C. ### Claim 8 (depends on 1) The process according to claim 1, wherein said PAA solution and said SAP dispersion each have a viscosity, and the viscosities form a viscosity ratio; and wherein the negative logarithm of said viscosity ratio is greater than about 3 and less than about 5. ### Claim 9 (depends on 1) The process according to claim 1, wherein said PAA has a molecular weight from about 1 to about 1,000 kDa. ### Claim 10 (depends on 1) The process according to claim 1, wherein said PAA has a molecular weight from about 50 to about 500 kDa. ### Claim 11 (depends on 1) The process according to claim 1, wherein the SAP concentration is from about 1% to about 30%. ### Claim 12 (depends on 1) The process according to claim 1, wherein the SAP concentration is from about 2% to about 30%. ### Claim 13 (depends on 1) The process according to claim 1, wherein the said SAP is added to the solution in one or more doses. ### Claim 14 (depends on 1) The process according to claim 1, wherein the SAP has an SAP Particle Size Distribution and wherein the SAP Particle Size Distribution is reported as D50 and is from about 5 to about 5,000 microns. ### Claim 15 (depends on 14) The process according to claim 14, wherein the D50 is from about 5 to about 1,000 microns. ### Claim 16 (depends on 14) The process according to claim 14, wherein the D50 is from about 3 to about 500 microns. ### Claim 17 (depends on 1) The process according to claim 1, wherein the oxidizer is persulfate with concentration from about 0.25 to about 5 g per 100 g of SAP. ### Claim 18 (depends on 1) The process according to claim 1, wherein the oxidizer is persulfate with concentration from about 0.8 to about 2 g per 100 g of SAP. ### Claim 19 (depends on 1) The process according to claim 1, further comprising the step of adding a bleaching agent. ### Claim 20 (depends on 19) The process according to claim 19, wherein the bleaching agent is Hydrogen Peroxide with a concentration from about 0.25 to about 5 g per 100 g of SAP. ### Claim 21 (depends on 20) The process according to claim 20, wherein the bleaching agent is Hydrogen Peroxide with a concentration from about 0.8 to about 2 g per 100 g of SAP. ### Claim 22 (depends on 19) The process according to claim 19, wherein the PAA exhibit Hunter LAB Color value of b* less than 15. ### Claim 23 (depends on 19) The process according to claim 19, wherein the PAA exhibit Hunter LAB Color value of b* less than 10. ### Claim 24 (depends on 19) The process according to claim 19, wherein the PAA exhibit Hunter LAB Color value of b* less than 7. ### Claim 25 (depends on 1) The process according to claim 1, where SAP is provided from pre-existing recycled post-consumer superabsorbent polymer material, and/or obtained from pre-existing recycled post-industrial superabsorbent polymer material or combinations thereof. ### Claim 26 (depends on 1) The process according to claim 1, wherein the SAP is in the form of at least one of particles, fibers, flakes, foams, nonwoven fabrics, woven fabrics, or mixtures thereof.