# US 2019/0169795 A1 · Method for recovering pulp fibers from used absorbent article > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0169795 A1 - Document ID: US20190169795A1 - Status: Published application - Kind: A1 - Application number: 16/321,829 - Filed: 2017-06-09 - Published: 2019-06-06 - Earliest claimed: 2016-08-05 - Assignees: Unicharm Corporation - Applicants: Unicharm Corporation - Inventors: Takayoshi KONISHI; Toshio HIRAOKA; Koichi YAMAKI; Noritomo KAMEDA - Web page: https://patentgrep.com/patent/US20190169795A1 ## CPC - D21C 5/022: {Chemicals therefor} - B09B 3/40: involving thermal treatment, e.g. evaporation (processes using mineral binders involving a melting or softening step B09B3/29; involving radiation B09B3/50) - B09B 3/70: Chemical treatment, e.g. pH adjustment or oxidation (involving an extraction step B09B3/80) - B29B 17/02: Separating plastics from other materials - C08J 11/04: of polymers - C08J 11/06: without chemical reactions - C08J 11/16: by treatment with inorganic material (C08J11/14 takes precedence) - D21B 1/021: {by chemical means} - D21B 1/026: {Separating fibrous materials from waste} - D21C 5/02: Working-up waste paper (mechanical part D21B1/08, D21B1/32) - B09B 2101/67: Diapers or nappies - B29L 2031/4878: {Diapers, napkins} - C08J 2300/14: Water soluble or water swellable polymers, e.g. aqueous gels - Y02E 50/30: Fuel from waste, e.g. synthetic alcohol or diesel - Y02P 20/143: the feedstock being recycled material, e.g. plastics - Y02W 30/62: Plastics recycling; Rubber recycling - Y02W 30/64: Paper recycling - D21C: PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR - B09B: DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR - B29B: PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS - 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) - D21B: FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT - B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS - Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT ## Abstract A method is provided for recovering pulp fibers having little damage from a used absorbent article that contains pulp fibers and a superabsorbent polymer. The used absorbent article is treated at a temperature of greater than or equal to 80° C. with an organic acid aqueous solution having a pH no greater than 2.5, and the superabsorbent polymer is deactivated. Preferably, the pulp fibers and the deactivated superabsorbent polymer are separated from the used absorbent article after treatment with the organic acid aqueous solution, and further, a mixture including the separated pulp fibers and deactivated superabsorbent polymer is treated with an oxidizing agent, the deactivated superabsorbent polymer is decomposed, reduced in molecular weight and solubilized. ## Claims ### Claim 1 A method of recovering pulp fibers from a used absorbent article containing pulp fibers and a superabsorbent polymer, wherein the method includes a step of treating the used absorbent article at a temperature of 80° C. or higher with an organic acid aqueous solution having a pH of no higher than 2.5, to inactivate the superabsorbent polymer. ### Claim 2 (depends on 1) The method according to claim 1, which further includes a step of separating the pulp fibers and a inactivated superabsorbent polymer from the used absorbent article that has been treated with the organic acid aqueous solution. ### Claim 3 (depends on 2) The method according to claim 2, which further includes a step of treating a mixture comprising separated pulp fibers and an inactivated superabsorbent polymer with an oxidizing agent to decompose, reduce in molecular weight and solubilize the inactivated superabsorbent polymer. ### Claim 4 (depends on 3) The method according to claim 3, which further includes a step of separating the pulp fibers from the mixture that has been treated with the oxidizing agent. ### Claim 5 (depends on 1) The method according to claim 1, wherein the organic acid is citric acid. ### Claim 6 (depends on 5) The method according to claim 5, wherein a citric acid concentration in the organic acid aqueous solution is 2 mass % or greater. ### Claim 7 (depends on 2) The method according to claim 2, wherein the used absorbent article includes a material composed of a thermoplastic resin, and the method further includes a step of drying a residue obtained from separating the pulp fibers and the inactivated superabsorbent polymer from the used absorbent article, and separating the material composed of a thermoplastic resin from a dried residue. ### Claim 8 (depends on 2) The method according to claim 2, wherein the used absorbent article includes a thermoplastic resin film, and the method further includes a step of drying a residue obtained from separating the pulp fibers and the inactivated superabsorbent polymer from the used absorbent article, and separating the thermoplastic resin film from a dried residue. ### Claim 9 (depends on 1) The method according to claim 1, wherein the absorbent article is at least one type selected from the group consisting of paper diapers, urine-absorbing pads, bed sheets, sanitary napkins and pet sheets.