CN111263670A - Method and system for recovering pulp fibers and superabsorbent polymers from used absorbent articles - Google Patents
Method and system for recovering pulp fibers and superabsorbent polymers from used absorbent articles Download PDFInfo
- Publication number
- CN111263670A CN111263670A CN201880068643.6A CN201880068643A CN111263670A CN 111263670 A CN111263670 A CN 111263670A CN 201880068643 A CN201880068643 A CN 201880068643A CN 111263670 A CN111263670 A CN 111263670A
- Authority
- CN
- China
- Prior art keywords
- pulp fibers
- aqueous solution
- superabsorbent polymer
- acidic aqueous
- super absorbent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
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- 239000000835 fiber Substances 0.000 title claims abstract description 305
- 238000000034 method Methods 0.000 title claims abstract description 105
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- 230000002745 absorbent Effects 0.000 title claims abstract description 95
- 239000004583 superabsorbent polymers (SAPs) Substances 0.000 title claims description 27
- 239000007864 aqueous solution Substances 0.000 claims abstract description 207
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- 239000000463 material Substances 0.000 claims abstract description 120
- 230000005484 gravity Effects 0.000 claims abstract description 81
- 238000000926 separation method Methods 0.000 claims abstract description 75
- 230000002779 inactivation Effects 0.000 claims abstract description 31
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 54
- 230000000415 inactivating effect Effects 0.000 claims description 12
- 238000002156 mixing Methods 0.000 claims description 7
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- 238000011282 treatment Methods 0.000 description 65
- 239000007788 liquid Substances 0.000 description 63
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 54
- 239000000243 solution Substances 0.000 description 34
- 239000007800 oxidant agent Substances 0.000 description 33
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- 230000007797 corrosion Effects 0.000 description 3
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- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 2
- RGHNJXZEOKUKBD-SQOUGZDYSA-N D-gluconic acid Chemical compound OC[C@@H](O)[C@@H](O)[C@H](O)[C@@H](O)C(O)=O RGHNJXZEOKUKBD-SQOUGZDYSA-N 0.000 description 2
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 description 2
- AEMRFAOFKBGASW-UHFFFAOYSA-N Glycolic acid Chemical compound OCC(O)=O AEMRFAOFKBGASW-UHFFFAOYSA-N 0.000 description 2
- 239000004831 Hot glue Substances 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 239000004677 Nylon Substances 0.000 description 2
- KFSLWBXXFJQRDL-UHFFFAOYSA-N Peracetic acid Chemical compound CC(=O)OO KFSLWBXXFJQRDL-UHFFFAOYSA-N 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 229920001131 Pulp (paper) Polymers 0.000 description 2
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 description 2
- 239000003929 acidic solution Substances 0.000 description 2
- 150000001336 alkenes Chemical class 0.000 description 2
- 229920002678 cellulose Polymers 0.000 description 2
- 239000001913 cellulose Substances 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- OSVXSBDYLRYLIG-UHFFFAOYSA-N dioxidochlorine(.) Chemical compound O=Cl=O OSVXSBDYLRYLIG-UHFFFAOYSA-N 0.000 description 2
- 229920001778 nylon Polymers 0.000 description 2
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 229920001707 polybutylene terephthalate Polymers 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 2
- 239000005020 polyethylene terephthalate Substances 0.000 description 2
- 230000001172 regenerating effect Effects 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 235000002906 tartaric acid Nutrition 0.000 description 2
- 239000011975 tartaric acid Substances 0.000 description 2
- BJEPYKJPYRNKOW-REOHCLBHSA-N (S)-malic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O BJEPYKJPYRNKOW-REOHCLBHSA-N 0.000 description 1
- VSKJLJHPAFKHBX-UHFFFAOYSA-N 2-methylbuta-1,3-diene;styrene Chemical compound CC(=C)C=C.C=CC1=CC=CC=C1.C=CC1=CC=CC=C1 VSKJLJHPAFKHBX-UHFFFAOYSA-N 0.000 description 1
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- 229920003043 Cellulose fiber Polymers 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 239000004155 Chlorine dioxide Substances 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- RGHNJXZEOKUKBD-UHFFFAOYSA-N D-gluconic acid Natural products OCC(O)C(O)C(O)C(O)C(O)=O RGHNJXZEOKUKBD-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 239000004820 Pressure-sensitive adhesive Substances 0.000 description 1
- 239000005708 Sodium hypochlorite Substances 0.000 description 1
- KDYFGRWQOYBRFD-UHFFFAOYSA-N Succinic acid Natural products OC(=O)CCC(O)=O KDYFGRWQOYBRFD-UHFFFAOYSA-N 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 235000011054 acetic acid Nutrition 0.000 description 1
- BJEPYKJPYRNKOW-UHFFFAOYSA-N alpha-hydroxysuccinic acid Natural products OC(=O)C(O)CC(O)=O BJEPYKJPYRNKOW-UHFFFAOYSA-N 0.000 description 1
- 230000001174 ascending effect Effects 0.000 description 1
- 239000011668 ascorbic acid Substances 0.000 description 1
- 229960005070 ascorbic acid Drugs 0.000 description 1
- 235000010323 ascorbic acid Nutrition 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000004061 bleaching Methods 0.000 description 1
- FACXGONDLDSNOE-UHFFFAOYSA-N buta-1,3-diene;styrene Chemical compound C=CC=C.C=CC1=CC=CC=C1.C=CC1=CC=CC=C1 FACXGONDLDSNOE-UHFFFAOYSA-N 0.000 description 1
- KDYFGRWQOYBRFD-NUQCWPJISA-N butanedioic acid Chemical compound O[14C](=O)CC[14C](O)=O KDYFGRWQOYBRFD-NUQCWPJISA-N 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- NKCVNYJQLIWBHK-UHFFFAOYSA-N carbonodiperoxoic acid Chemical compound OOC(=O)OO NKCVNYJQLIWBHK-UHFFFAOYSA-N 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 235000019398 chlorine dioxide Nutrition 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000004332 deodorization Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 239000000174 gluconic acid Substances 0.000 description 1
- 235000012208 gluconic acid Nutrition 0.000 description 1
- 229940093915 gynecological organic acid Drugs 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 description 1
- 239000001630 malic acid Substances 0.000 description 1
- 235000011090 malic acid Nutrition 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 239000002101 nanobubble Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 238000006864 oxidative decomposition reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229920000058 polyacrylate Polymers 0.000 description 1
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- 239000011148 porous material Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 239000004627 regenerated cellulose Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 229920001935 styrene-ethylene-butadiene-styrene Polymers 0.000 description 1
- 229920003047 styrene-styrene-butadiene-styrene Polymers 0.000 description 1
- 210000002700 urine Anatomy 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
- B09B3/70—Chemical treatment, e.g. pH adjustment or oxidation
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F5/00—Orthopaedic methods or devices for non-surgical treatment of bones or joints; Nursing devices; Anti-rape devices
- A61F5/44—Devices worn by the patient for reception of urine, faeces, catamenial or other discharge; Portable urination aids; Colostomy devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B1/00—Conditioning for facilitating separation by altering physical properties of the matter to be treated
- B03B1/04—Conditioning for facilitating separation by altering physical properties of the matter to be treated by additives
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B5/00—Washing granular, powdered or lumpy materials; Wet separating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B5/00—Washing granular, powdered or lumpy materials; Wet separating
- B03B5/28—Washing granular, powdered or lumpy materials; Wet separating by sink-float separation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B9/00—General arrangement of separating plant, e.g. flow sheets
- B03B9/06—General arrangement of separating plant, e.g. flow sheets specially adapted for refuse
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE
- B09B5/00—Operations not covered by a single other subclass or by a single other group in this subclass
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- 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
- B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
- B29B17/02—Separating plastics from other materials
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
- D21B1/00—Fibrous raw materials or their mechanical treatment
- D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
- D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
- D21B1/30—Defibrating by other means
- D21B1/32—Defibrating by other means of waste paper
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/20—Waste processing or separation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/52—Mechanical processing of waste for the recovery of materials, e.g. crushing, shredding, separation or disassembly
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
Abstract
A method for separating a superabsorbent polymer from pulp fibers with high processing efficiency when recovering the pulp fibers and the superabsorbent polymer from a used absorbent article is provided. The method comprises the following steps: an inactivation step (S13) in which pulp fibers and a superabsorbent polymer separated from a used absorbent article are mixed with an acidic aqueous solution to inactivate the superabsorbent polymer, the acidic aqueous solution having a pH adjusted so that the difference between the specific gravity and the size of the superabsorbent polymer and the specific gravity and the size of the pulp fibers fall within a predetermined range, respectively; a size separation step (S15) in which pulp fibers and a superabsorbent polymer are separated from other materials by a difference in size while maintaining the pH within a predetermined range in an acidic aqueous solution containing the pulp fibers and the superabsorbent polymer; and a specific gravity separation step (S16) in which pulp fibers and a superabsorbent polymer are separated from other materials by utilizing the difference in specific gravity while maintaining the pH within a predetermined range in an acidic aqueous solution containing the pulp fibers and the superabsorbent polymer.
Description
Technical Field
The present invention relates to a method and system for recovering pulp fibers and superabsorbent polymers from used absorbent articles.
Background
A method of recovering pulp fibers and superabsorbent polymers from used absorbent articles such as disposable diapers is known. For example, patent document 1 discloses a method for separating and recovering fibers and a super absorbent polymer from a used paper diaper. In this method, first, a used paper diaper is put into a pulper and dispersed in water to produce a slurry. Next, the slurry was treated with a screen and a cleaner to recover a super absorbent polymer. Thereafter, the dispersion containing the remaining fibers was treated with a washer, dehydrator, or screen to recover the fibers.
Documents of the prior art
Patent document
Patent document 1: international publication No. 2014/007105
Disclosure of Invention
Problems to be solved by the invention
In the method of patent document 1, first, a superabsorbent polymer is separated and recovered from a mixture of a superabsorbent polymer, fibers, and other raw materials of a used paper diaper, and then, fibers are separated and recovered from a mixture of pulp fibers and other raw materials. Thus, in any case, the superabsorbent polymer/pulp fibers are separated from the mixture with other raw materials. Therefore, if a super absorbent polymer and pulp fibers containing almost no other raw materials are to be obtained, it is necessary to separate the super absorbent polymer and the pulp fibers with high accuracy. In this case, the time taken for the separation process becomes long, and the efficiency of the separation process may be reduced. Therefore, in the case of recovering pulp fibers and superabsorbent polymers from used absorbent articles, there is room for improvement from the viewpoint of improving the efficiency of the separation treatment. A technique capable of separating a superabsorbent polymer and pulp fibers with high processing efficiency when recovering pulp fibers and superabsorbent polymers from used absorbent articles is desired.
The object of the present invention is to provide a method and a system capable of separating a superabsorbent polymer and pulp fibers with high processing efficiency when recovering pulp fibers and the superabsorbent polymer from a used absorbent article.
Means for solving the problems
The method of recovering pulp fibers and superabsorbent polymer from a used absorbent article comprising pulp fibers and superabsorbent polymer of the present invention is as follows. (1) A method of recovering pulp fibers and superabsorbent polymer from a used absorbent article comprising pulp fibers and superabsorbent polymer, wherein the method comprises: an inactivation step of mixing pulp fibers and a superabsorbent polymer separated from a used absorbent article with an acidic aqueous solution having a pH adjusted so that a difference between a specific gravity of the superabsorbent polymer and a specific gravity of the pulp fibers falls within a predetermined range and a difference between a size of the superabsorbent polymer and a size of the pulp fibers falls within a predetermined range, and inactivating the superabsorbent polymer; a size separation step of separating the pulp fibers and the superabsorbent polymer from other materials by a difference in size while maintaining the pH value within a predetermined range in the acidic aqueous solution containing the pulp fibers and the superabsorbent polymer; and a specific gravity separation step of separating the pulp fibers and the superabsorbent polymer from other materials by a difference in specific gravity while maintaining the pH within a predetermined range in the acidic aqueous solution containing the pulp fibers and the superabsorbent polymer.
Generally, the specific gravity of a super absorbent polymer is higher than that of water, but when the super absorbent polymer absorbs water, the water absorption amount is close to the specific gravity of water. The superabsorbent polymer has a small size, but when the superabsorbent polymer absorbs water, the superabsorbent polymer increases in size according to the amount of water absorbed. In addition, the amount of water that the super absorbent polymer can absorb and hold is very large, but the amount is limited to a certain extent by performing the inactivation treatment on the super absorbent polymer. From the above, the size and specific gravity of the super absorbent polymer can be adjusted to desired values by adjusting the amount of water held by the super absorbent polymer by the degree of inactivation treatment of the super absorbent polymer. Examples of the inactivation treatment of the super absorbent polymer include a treatment of immersing the super absorbent polymer in a predetermined solution (exemplified by an acidic aqueous solution).
Therefore, the method inactivates the super absorbent polymer with the pH-adjusted acidic aqueous solution in the inactivation step, and adjusts the water absorption capacity of the super absorbent polymer so that the specific gravity and the size of the super absorbent polymer are within predetermined ranges from those of the pulp fibers, respectively. In this case, the predetermined range is, for example, 0.2 to 5 times as large as one another. Thus, the specific gravity and the size of the difference between the pulp fiber and the super absorbent polymer are within predetermined ranges. As a result, the pulp fibers and the super absorbent polymer can be easily separated from the other materials (mainly, resin materials) other than the pulp fibers and the super absorbent polymer in the material of the used absorbent article by the difference in size, and can be easily separated from the materials (mainly, metal materials) having a larger specific gravity among the other materials by the difference in specific gravity. Further, by separating the pulp fibers and the super absorbent polymer from each other thereafter, the pulp fibers and the super absorbent polymer can be recovered from the used absorbent article. In this case, the number of times of treatment for separating pulp fibers and super absorbent polymers from other materials can be reduced. That is, the efficiency of the process of separating the super absorbent polymer and the pulp fiber can be improved. Examples of the resin material of the used absorbent article other than pulp fibers and superabsorbent polymers include films (back sheets and the like), nonwoven fabrics (front sheets and the like), and elastomers (rubber for leakproof walls and the like). As the material having a large specific gravity among the other materials, for example, the metal material, a clip which is not originally included in the absorbent article but is mixed in when the used absorbent article is recovered, a staple of a stapler, and the like can be cited. The size of the super absorbent polymer means the particle diameter of the super absorbent polymer, and is a diameter in the case where the super absorbent polymer is spherical, and a longest width in the case of a block. The size of the pulp fibers is set to the average fiber length of the pulp fibers. The predetermined range of the pH value is a range in which the variation of the pH value is within. + -. 1.0.
The method may be (2) the method according to the above (1), wherein the specific gravity separation step includes a step of separating the pulp fibers and the super absorbent polymer from the other materials by a centrifugal separation method.
The difference between the specific gravity of the pulp fiber and the specific gravity of the super absorbent polymer in the method is within a predetermined range. Therefore, the pulp fibers and the super absorbent polymer can be more accurately separated from other materials (materials having a larger specific gravity, such as metal materials) by the centrifugal separation method. This can improve the efficiency of the process of separating the super absorbent polymer and the pulp fibers.
The method may be (3) the method according to the above (1) or (2), wherein the size separation step includes a screen separation step of separating the pulp fibers and the superabsorbent polymer from the other material using a screen having a plurality of openings with a predetermined size.
The difference between the size of the pulp fibers and the size of the superabsorbent polymer in the present process is within a predetermined range. Therefore, pulp fibers and super absorbent polymer can be more accurately separated from other materials (mainly resin members, for example, films such as back sheets, nonwoven fabrics such as front sheets, and elastic leakage preventing wall rubber) by passing them through a screen having a plurality of openings of a predetermined size. This can improve the efficiency of the process of separating the super absorbent polymer from the pulp fibers.
The method may be (4) the method according to any one of the above (1) to (3), wherein a rough size separation step is included before the size separation step, and in the rough size separation step, the pulp fibers and the superabsorbent polymer are separated from the other material by passing the pulp fibers and the superabsorbent polymer through a screen having a plurality of openings larger than a plurality of openings of a screen used in the size separation step while maintaining the pH within a predetermined range in the acidic aqueous solution containing the pulp fibers and the superabsorbent polymer.
The present method enables the removal of relatively large amounts of other materials by passing them through a screen having larger openings prior to the size separation process. This can prevent the screen from being clogged with relatively large other materials in the size separation step, thereby reducing the efficiency of the separation process.
The method may be (5) the method according to any one of (1) to (4) above, wherein a ratio of the pulp fibers and the superabsorbent polymer in the acidic aqueous solution formed in the inactivation step is 0.1 mass% or more and 10 mass% or less.
In the method, the pulp fibers and the super absorbent polymer in the acidic aqueous solution are more reliably separated from other materials by setting the ratio of the pulp fibers and the super absorbent polymer to 0.1 mass% or more and 10 mass% or less. This can improve the efficiency of the process of separating the super absorbent polymer and the pulp fibers. However, if the amount of the super absorbent polymer and the pulp fiber to be separated is less than 0.1 mass%, the separating ability becomes wasteful, and if the amount is more than 10 mass%, the super absorbent polymer and the pulp fiber cannot be completely separated and discharged together with other materials, and in any case, the efficiency of the treatment is lowered.
The method according to any one of (1) to (5) above, wherein the pH of the acidic aqueous solution is 1 or more and 4 or less.
In the method, the pH of the acidic aqueous solution is adjusted to 1 or more and 4 or less, and therefore the specific gravity and the size of the super absorbent polymer and the specific gravity and the size of the pulp fiber can be brought closer to each other. This enables pulp fibers and superabsorbent polymers to be more reliably separated from other materials. This can improve the efficiency of the process of separating the super absorbent polymer and the pulp fibers.
The method may be (7) the method according to any one of (1) to (6) above, wherein the acidic aqueous solution contains citric acid.
In this method, since the acidic aqueous solution contains citric acid (exemplified as a concentration of 0.5 to 2.0% by mass), the super absorbent polymer can be dehydrated reliably, and the specific gravity and the size of the super absorbent polymer are set to values closer to those of pulp fibers, respectively. This enables pulp fibers and superabsorbent polymers to be more reliably separated from other materials. Further, adverse effects of the acid on the operator and corrosion of the equipment in each step can be suppressed. This can improve the efficiency of the process of separating the super absorbent polymer and the pulp fibers.
The method may be (8) the method according to any one of (1) to (7) above, further comprising a polymer separation step of separating the superabsorbent polymer from the acidic aqueous solution containing the pulp fiber and the superabsorbent polymer separated in the specific gravity separation step.
In the method, other materials are removed from the pulp fiber and the super absorbent polymer, and therefore the pulp fiber and the super absorbent polymer can be easily recovered separately by separating them from each other.
The system used for recovering pulp fibers and superabsorbent polymers from used absorbent articles comprising pulp fibers and superabsorbent polymers of the present invention is as follows. (9) A system for recovering pulp fibers and superabsorbent polymer from a used absorbent article comprising pulp fibers and superabsorbent polymer, wherein the system comprises: a screen separator that maintains a pH value in a predetermined range in an acidic aqueous solution containing pulp fibers and a superabsorbent polymer, in which the superabsorbent polymer has been inactivated by mixing the pulp fibers and the superabsorbent polymer separated from used absorbent articles with the acidic aqueous solution, while separating the pulp fibers and the superabsorbent polymer from other materials using a screen having a plurality of openings of a predetermined size, wherein the acidic aqueous solution adjusts the pH value in such a manner that a difference in specific gravity of the superabsorbent polymer and a difference in specific gravity of the pulp fibers are within the predetermined range and a difference in size of the superabsorbent polymer and a difference in size of the pulp fibers are within the predetermined range; and a cyclone that separates the pulp fibers and the superabsorbent polymer from the other materials by a centrifugal separation method while maintaining the pH value within a predetermined range in the acidic aqueous solution containing the pulp fibers and the superabsorbent polymer.
The system inactivates the super absorbent polymer with the pH-adjusted acidic aqueous solution, and adjusts the water absorption capacity of the super absorbent polymer so that the specific gravity and the size of the super absorbent polymer are within predetermined ranges from those of pulp fibers, respectively. Thus, the specific gravity and the size of the difference between the pulp fiber and the super absorbent polymer are within predetermined ranges. As a result, the pulp fibers and the super absorbent polymer can be easily separated from the resin material, which is the main material of the used absorbent article, among the materials other than the pulp fibers and the super absorbent polymer, and can be easily separated from the material having a large specific gravity, such as the metal material, among the other materials, by the difference in specific gravity. Further, by separating the pulp fibers and the super absorbent polymer from each other thereafter, the pulp fibers and the super absorbent polymer can be recovered from the used absorbent article. In this case, the super absorbent polymer and the pulp fibers are not separated from the mixture mixed with the other material independently from each other, and therefore the number of times the pulp fibers and the super absorbent polymer are separated from the other material can be reduced. That is, the efficiency of the process of separating the super absorbent polymer and the pulp fiber can be improved.
The present system may be (10) the system according to (9) above, further comprising a coarse screen separator before the screen separator, the coarse screen separator maintaining the pH value in the acidic aqueous solution containing the pulp fibers and the superabsorbent polymer within a predetermined range while separating the pulp fibers and the superabsorbent polymer from the other materials through a screen having a plurality of openings larger than the plurality of openings of the predetermined size.
The present system is provided with a coarse screen separator before the screen separator, so by passing it through a screen having a larger plurality of openings, relatively large other materials can be removed before the screen separator. This can prevent the screen from being clogged with relatively large materials before the screen separator, thereby reducing the efficiency of the separation process.
The present system may be (11) the system according to the above (9) or (10), wherein a ratio of the pulp fibers and the superabsorbent polymer in the acidic aqueous solution containing the inactivated superabsorbent polymer is 0.1 mass% or more and 10 mass% or less.
In the present system, the pulp fibers and the super absorbent polymer can be more reliably separated from other materials by setting the ratio of the pulp fibers and the super absorbent polymer in the acidic aqueous solution to 0.1 mass% or more and 10 mass% or less. This can improve the efficiency of the process of separating the super absorbent polymer and the pulp fibers. However, if the amount of the super absorbent polymer and the pulp fiber to be separated is less than 0.1 mass%, the separating ability becomes wasteful, and if the amount is more than 10 mass%, the super absorbent polymer and the pulp fiber cannot be completely separated and discharged together with other materials, and in any case, the efficiency of the treatment is lowered.
The present system may be (12) the system according to any one of (9) to (11) above, wherein the pH of the acidic aqueous solution is 1 or more and 4 or less.
In the present system, since the pH of the acidic aqueous solution is adjusted to 1 or more and 4 or less, the specific gravity and the size of the super absorbent polymer and the specific gravity and the size of the pulp fiber can be set to values closer to each other. This enables pulp fibers and superabsorbent polymers to be more reliably separated from other materials. This can improve the efficiency of the process of separating the super absorbent polymer and the pulp fibers.
The system according to any one of (9) to (12) above, wherein (13) the acidic aqueous solution contains citric acid.
In this system, since the acidic aqueous solution contains citric acid (exemplified as a concentration of 0.5 to 2.0% by mass), the super absorbent polymer can be dehydrated reliably, and the specific gravity and the size of the super absorbent polymer are set to values closer to those of pulp fibers, respectively. This enables pulp fibers and superabsorbent polymers to be more reliably separated from other materials. Further, adverse effects of the acid on the operator and corrosion of the equipment in each step can be suppressed. This can improve the efficiency of the process of separating the super absorbent polymer and the pulp fibers.
The present system may be (14) the system according to any one of (9) to (13), further comprising a trommel separator for separating the superabsorbent polymer from the acidic aqueous solution containing the pulp fibers and the superabsorbent polymer separated by the cyclone separator by a trommel.
In the present system, since a trommel separator is provided, after removing other materials from the pulp fibers and the super absorbent polymer, the pulp fibers and the super absorbent polymer can be easily recovered separately by separating them from each other.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the method and system of the present invention, when pulp fibers and superabsorbent polymers are recovered from used absorbent articles, the superabsorbent polymers and pulp fibers can be separated with high processing efficiency.
Drawings
Fig. 1 is a block diagram showing an example of a system according to the embodiment.
Fig. 2 is a schematic diagram showing a configuration example of the bag-breaking device and the breaking device in fig. 1.
Fig. 3 is a flowchart showing an example of the method according to the embodiment.
Detailed Description
Hereinafter, a method of recovering pulp fibers from a used absorbent article including pulp fibers and a super absorbent polymer according to an embodiment will be described. The term "used absorbent article" as used herein means an absorbent article used by a user, including an absorbent article in a state of absorbing and retaining excrement of the user, and also includes an absorbent article which has been used but has not absorbed and retained excrement, and an absorbent article which has not been used but has been discarded. Examples of the absorbent article include disposable diapers, urine absorbent pads, sanitary napkins, bed sheets, and pet sheets. In the method of recovering pulp fibers from a used absorbent article according to the present embodiment, recycled pulp fibers are produced, and therefore, the method can be said to be a method of producing recycled pulp fibers from a used absorbent article. Further, the method of recovering pulp fibers from a used absorbent article of the present embodiment recovers a super absorbent polymer together with pulp fibers in the middle and produces a recycled super absorbent polymer by separation, and thus can be said to be a method of recovering a super absorbent polymer from a used absorbent article or a method of producing a recycled super absorbent polymer. Here, a method of recovering pulp fibers from a used absorbent article will be described.
First, a configuration example of the absorbent article will be described. The absorbent article includes a front sheet, a back sheet, and an absorber disposed between the front sheet and the back sheet. Examples of the size of the absorbent article include a length of about 15cm to 100cm and a width of 5cm to 100 cm. The absorbent article may include further other members, such as a diffusion sheet and a leakage preventing wall, which are included in a general absorbent article.
Examples of the structural member of the top sheet include a liquid-permeable nonwoven fabric, a liquid-permeable synthetic resin film having liquid-permeable pores, and a composite sheet thereof. Examples of the structural member of the back sheet include a liquid-impermeable nonwoven fabric, a liquid-impermeable synthetic resin film, and a composite sheet thereof. Examples of the structural member of the diffusion sheet include liquid-permeable nonwoven fabrics. The structural member of the leakage preventing wall may be, for example, a liquid impermeable nonwoven fabric, or may include an elastic member such as rubber. Here, the material of the nonwoven fabric and the synthetic resin film is not particularly limited as long as it can be used as an absorbent article, but examples thereof include olefin-based resins such as polyethylene and polypropylene, polyamide-based resins such as 6-nylon and 6, 6-nylon, and polyester-based resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). In the present embodiment, an absorbent article in which the structural member of the back sheet is a film and the structural member of the front sheet is a nonwoven fabric will be described as an example.
As the structural member of the absorbent body, absorbent body materials, that is, pulp fibers and super absorbent polymers can be cited. The pulp fiber is not particularly limited as long as it can be used as an absorbent article, but for example, a cellulose fiber is exemplified. Examples of the cellulose-based fibers include wood pulp, crosslinked pulp, non-wood pulp, regenerated cellulose, and semi-synthetic cellulose. The pulp fiber has an average length of several tens of micrometers, preferably 20 to 40 micrometers, and an average fiber length of several mm, preferably 2 to 5 mm. The Super Absorbent Polymer (SAP) is not particularly limited as long as it can be used as an absorbent article, but examples thereof include polyacrylate-based, polysulfonate-based, and maleic anhydride-based water absorbent polymers. The average particle size of the superabsorbent polymer (when dry) is, for example, several hundred microns, preferably 200 to 500 microns.
One surface and the other surface of the absorbent body are bonded to the front sheet and the back sheet, respectively, with an adhesive. In a plan view, a portion (peripheral portion) of the front sheet that extends outward of the absorber so as to surround the absorber is joined to a portion (peripheral portion) of the back sheet that extends outward of the absorber so as to surround the absorber via an adhesive. Therefore, the absorbent body is enclosed in the joined body of the front sheet and the back sheet. The adhesive is not particularly limited as long as it can be used as an absorbent article and the adhesive strength is reduced by softening with warm water or the like described later, but examples thereof include a hot-melt adhesive. Examples of the hot-melt adhesive include a pressure-sensitive adhesive or a heat-sensitive adhesive containing a rubber-based body such as styrene-ethylene-butadiene-styrene, styrene-butadiene-styrene, or styrene-isoprene-styrene, or an olefin-based body such as polyethylene.
Next, a method of recovering pulp fibers from a used absorbent article including pulp fibers and a super absorbent polymer according to an embodiment will be described. In the present embodiment, the used absorbent article is recovered/taken from the outside and used for reuse (recycling). At this time, a plurality of used absorbent articles are enclosed in a collecting bag (hereinafter, also referred to as "collecting bag") so that dirt (excrement, etc.), fungi, and odor do not leak to the outside. In order to prevent the excrement from being exposed to the front surface side and prevent the odor from diffusing to the surroundings, each used absorbent article in the collecting bag is collected mainly in a state of being rolled up or in a folded state so that the front surface sheet on which the excrement is excreted is positioned inside.
First, a system 1 used in a method of recovering pulp fibers from a used absorbent article will be described. System 1 is a system for recovering pulp fibers and superabsorbent polymer from a used absorbent article to produce recycled pulp fibers and recycled superabsorbent polymer. Fig. 1 is a block diagram showing an example of a system 1 according to the present embodiment. The system 1 comprises a 2 nd dust removal device 15 and a 3 rd dust removal device 16, and preferably further comprises a bag breaking device 11, a crushing device 12, a 1 st separation device 13, a 1 st dust removal device 14, a 2 nd separation device 17, a 3 rd separation device 18, an oxidant treatment device 19 and a 4 th separation device 20. The following description will be made in detail.
First, the bag breaker 11 and the breaker 12 will be described. The bag breaking device 11 opens a collecting bag containing used absorbent articles in the inactivating aqueous solution. The breaking device 12 breaks up used absorbent articles that have fallen in the inactivating water solution below the water surface of the inactivating water solution together with the collecting bag. Wherein the inactivation aqueous solution is an aqueous solution in which the super absorbent polymer is inactivated, and the water absorption performance of the super absorbent polymer is reduced by inactivation. Thus, the super absorbent polymer releases water to an amount that can be tolerated by the water absorption properties, i.e., dehydrates, while absorbing more water than the reduced water absorption properties. Hereinafter, a case of using an acidic aqueous solution as the inactivation aqueous solution will be described as an example.
Fig. 2 is a schematic diagram showing a configuration example of the bag breaker 11 and the breaker 12 in fig. 1.
The bag-breaking device 11 stores an acidic aqueous solution B supplied through, for example, a pipe having a valve, and opens a hole in a collection bag a put in the acidic aqueous solution B. The bag-breaking device 11 includes a solution tank V and an opening portion 50. The solution tank V is for storing the acidic aqueous solution B. The opening portion 50 is provided in the solution tank V, and opens a hole in the surface of the collection bag a that comes into contact with the acidic aqueous solution B when the collection bag a is placed in the solution tank V.
The opening portion 50 includes the feeding portion 30 and the bag breaking portion 40. The sending unit 30 sends (introduces) the collection bag a (physically and forcibly) into the acidic aqueous solution B in the solution tank V. The feeding portion 30 is, for example, a mixer, and includes a mixing blade 33, a support shaft (rotation shaft) 32 for supporting the mixing blade 33, and a driving device 31 for rotating the support shaft 32 along an axis. The stirring blade 33 is rotated about a rotation shaft (support shaft 32) by the driving device 31, thereby generating a vortex in the acidic aqueous solution B. The feeding unit 30 draws the collection bag a in the bottom direction of the acidic aqueous solution B (solution tank V) by a vortex.
The bag breaking portion 40 is disposed at a lower portion (preferably, a bottom portion) of the solution tank V, and includes a bag breaking blade 41, a support shaft (rotation shaft) 42 for supporting the bag breaking blade 41, and a driving device 43 for rotating the support shaft 42 along an axis. The bag breaking blade 41 is rotated about a rotation shaft (support shaft 42) by a driving device 43 to open a hole in the collection bag a moved to the lower portion of the acidic aqueous solution B (solution tank V). The lower portion of the solution tank V represents a portion below a position half way in the height direction of the solution tank V.
The bag breaking blade 41 of the hole portion 50 of the bag breaking device 11 may be movable in the vertical direction in the solution tank V while rotating around a rotation shaft (support shaft 42). In this case, the bag-breaking blade 41 moves upward, so that the collection bag a can be perforated even if the collection bag a does not move to the lower portion of the acidic aqueous solution B (solution tank V).
The crushing device 12 crushes the used absorbent articles in the collection bag a that sinks below the water surface of the acidic aqueous solution B together with the collection bag a. The crushing device 12 comprises a crushing section 60 and a pump 63. The crushing unit 60 is connected to the solution tank V by a pipe 61, and crushes the used absorbent article (the mixed liquid 91) in the collection bag a, which is sent out from the solution tank V together with the acidic aqueous solution B, in the acidic aqueous solution B together with the collection bag a. Examples of the crushing section 60 include a twin-shaft crusher (exemplified by a twin-shaft rotary crusher, a twin-shaft differential crusher, and a twin-shaft shear crusher), such as sumituter (manufactured by sumitomo heavy mechanical environment co.). The pump 63 is connected to the crusher 60 by a pipe 62, and the crushed product obtained by the crusher 60 is pumped out from the crusher 60 together with the acidic aqueous solution B (mixed liquid 92) and sent to the next step. The crushed material contains pulp fibers, a super absorbent polymer, and other materials (a raw material of the collection bag a, a film, a nonwoven fabric, an elastomer, and the like). The bag breaking device 11 and the crushing device 12 are preferably different devices from each other.
Referring to fig. 1, the 1 st separator 13 stirs a mixed solution 92 containing the crushed material obtained by the crusher 12 and the acidic aqueous solution, removes dirt (excrement, etc.) from the crushed material, cleans the crushed material, separates pulp fibers, the super absorbent polymer, and the acidic aqueous solution (mixed solution 93) from the mixed solution 92, and sends the separated pulp fibers, the super absorbent polymer, and the acidic aqueous solution to the 1 st dust collector 14.
The 1 st separating device 13 may be, for example, a washing machine having a washing/dewatering tub and a water tub surrounding the washing/dewatering tub. Among them, the washing tank and dehydration tank (rotary drum) is used as a washing tank and sieve tank (separation tank). The size of the through-holes provided in the circumferential surface of the washing tank is set to a size at which pulp fibers and superabsorbent polymer in the crushed material easily pass through and other materials are difficult to pass through. An example of the washing machine is a horizontal washing machine ECO-22B (manufactured by Kagaku corporation).
It should be noted that the used absorbent article may be crushed together with the collecting bag in a gas (for example, in the air) instead of crushing the used absorbent article together with the collecting bag in the inactivating aqueous solution (for example, an acidic aqueous solution). In this case, the bag breaking device 11 is not required, and the breaking device 12 breaks in the air in a state where the aqueous inactivation solution is not present. Thereafter, the crushed material and the aqueous inactivation solution of the crushing apparatus 12 are supplied to the 1 st separation apparatus 13.
In the case where an acidic aqueous solution is not used as the inactivation aqueous solution between the bag-breaking device 11 and the 1 st separation device 13, the acidic aqueous solution is fed from the 1 st dust-removal device 14 so that the inactivation aqueous solution containing the pulp fibers and the super absorbent polymer supplied to the 1 st dust-removal device 14 becomes substantially an acidic aqueous solution.
The 1 st dust removing device 14 separates the acidic aqueous solution (mixed solution 93) containing pulp fibers and a super absorbent polymer sent from the 1 st separating device 13 into pulp fibers and a super absorbent polymer (mixed solution 94) in the acidic aqueous solution and other materials (foreign substances) by a sieve having a plurality of openings while maintaining the pH within a predetermined range. In order to maintain the pH within a predetermined range, for example, a liquid (exemplified by water) which fluctuates the pH is not added in the middle, or a liquid (exemplified by an acidic aqueous solution) which has substantially the same pH when a liquid is added. The predetermined range is a range in which the variation in pH is within. + -. 1.0.
The first dust removing device 14 may be, for example, a screen separator (coarse screen separator). The openings of the screen (screen) are not particularly limited, and examples thereof include slits, round holes, square holes, and nets, and here, round holes are used. The size of the openings, i.e., the size (diameter) of the circular holes is set to a size through which pulp fibers and super absorbent polymer can pass, and is a size through which other materials (foreign matters) that cannot be removed by the 1 st separator 13 hardly pass, and is larger than the size of the openings of the screen of the 2 nd dust collector 15. The size of the circular hole is, for example, 2mm to 5mm in diameter, whereby other materials (foreign matters) at least about 10mm square or more can be removed. In the case of the slit, the size (width) of the slit is, for example, 2mm to 5 mm.
From the viewpoint of improving the efficiency of removing foreign matter, the mixed liquid 93 sent from the 1 st separation device 13 may be pressurized and simultaneously (for example: 0.5 kgf/cm)2～1kgf/cm2) And then supplied to the 1 st dust removing device 14. The first dust removing device 14 is exemplified by a package pulper (manufactured by satomi corporation).
The 2 nd dust removing device 15 separates the acidic aqueous solution (mixed solution 94) containing pulp fibers and a super absorbent polymer sent out from the 1 st dust removing device 14 into pulp fibers and a super absorbent polymer (mixed solution 95) in the acidic aqueous solution and other materials (foreign matters) by a sieve having a plurality of openings while maintaining the pH value within a predetermined range.
The 2 nd dust removing device 15 is exemplified by a screen separator. The openings of the screen (screen) are not particularly limited, and examples thereof include slits, round holes, square holes, and nets, and slits are used herein. The size (width) of the slit is set to a size that pulp fibers and super absorbent polymer can pass through and is a size that other materials (foreign materials) that cannot be removed by the 1 st dust removing device 14 are difficult to pass through. The size of the slit is, for example, 0.2mm to 0.5mm in width, whereby other materials (foreign substances) at least about 3mm square or more can be removed. In the case of a circular hole, the size (diameter) of the circular hole is, for example, 0.2mm to 0.5mm phi in diameter.
From the viewpoint of improving the efficiency of removing foreign matter, the mixed liquid 94 sent from the 1 st dust removing device 14 may be pressurized and simultaneously (for example: 0.5 kgf/cm)2～2kgf/cm2) And supplied to the 2 nd dust removing device 15. From the viewpoint of removing relatively small foreign matters, the pressure is preferably higher than that of the 1 st dust removing device 14. The second dust removing device 15 is, for example, a Lamo sieve (manufactured by Acheki Kaisha).
The 3 rd dust removing device 16 centrifugally separates the acidic aqueous solution (mixed solution 95) containing pulp fibers and a super absorbent polymer, which is sent from the 2 nd dust removing device 15, while maintaining the pH value within a predetermined range, and separates the pulp fibers and the super absorbent polymer (mixed solution 96) in the acidic aqueous solution from other materials (foreign substances having a large weight).
The 3 rd dust removing device 16 is exemplified by a cyclone. An acidic aqueous solution (mixed solution 95) containing pulp fibers and a super absorbent polymer is supplied into an inverted conical casing (not shown) of the 3 rd dust removing device 16 at a predetermined flow rate so that the pulp fibers and the super absorbent polymer in the acidic aqueous solution having a relatively low specific gravity rise and foreign substances (metals, etc.) having a specific gravity higher than that of the pulp fibers and the super absorbent polymer fall. An example of the 3 rd dust removing device 16 is an ACT low concentration cleaner (manufactured by Kogaku K.K.).
The 2 nd separating device 17 separates the acidic aqueous solution (mixed solution 96) containing pulp fibers and a super absorbent polymer sent out from the 3 rd dust removing device 16 into pulp fibers (mixed solution 97) in the acidic aqueous solution and a super absorbent polymer in the acidic aqueous solution by a sieve having a plurality of openings. Therefore, the dehydrator can be considered as a dehydrator for removing the acidic aqueous solution together with the super absorbent polymer from the mixed liquid 96.
The 2 nd separating device 17 is exemplified by a trommel separator. The openings of the trommel (screen) are not particularly limited, and examples thereof include slits, round holes, square holes, and meshes. The size (width) of the slit is set to a size through which the super absorbent polymer can pass, and is a size through which the pulp fibers are difficult to pass. In the case of slits, the size of the slits is, for example, 0.2mm to 0.8mm in width, whereby at least a large amount of the super absorbent polymer can be removed. In the case of a circular hole, the size of the circular hole is, for example, 0.2mm to 0.8mm phi in diameter. The 2 nd separating device 17 may be a trommel dehydrator (manufactured by Toyo Sieve Co., Ltd.).
The 3 rd separating device 18 separates the pulp fibers, the remaining superabsorbent polymer that cannot be separated, and the acidic aqueous solution (mixed solution 97) sent from the 2 nd separating device 17 into a solid (mixture 98) containing the pulp fibers and the superabsorbent polymer and a liquid containing the superabsorbent polymer and the acidic aqueous solution by a sieve having a plurality of openings, and applies pressure to the solid to crush the superabsorbent polymer in the solid. Therefore, the 3 rd separator 18 can be regarded as a dehydration machine of a pressure dehydration system for removing the acidic aqueous solution together with the super absorbent polymer from the mixed liquid 97. Wherein the solids (mixture 98) contain some acidic water solubility.
The 3 rd separating device 18 is exemplified by a screw press dehydrator. The spiral screen comprises a cylindrical drum screen, a spiral shaft extending along the axis of a cylinder of the drum screen, and spiral blades arranged on the outer side of the spiral shaft and rotating along the inner circumferential surface of the drum screen. The openings of the trommel (screen) are not particularly limited, and examples thereof include slits, round holes, square holes, and meshes. The size (width) of the slit is set to a size through which the super absorbent polymer can pass, and is a size in which it is difficult to pass the pulp fiber. In the case of the slit, the size of the slit is, for example, 0.1mm to 0.5mm in width, and at least the remaining super absorbent polymer can be removed. The 3 rd separating device 18 sends out the liquid containing the super absorbent polymer and the acidic aqueous solution from the slit on the side of the trommel screen, and simultaneously sends out the solid containing the pulp fibers and the super absorbent polymer while crushing the super absorbent polymer from the gap of the cover body after the pressing of the top end of the trommel screen is adjusted. The pressure applied to the lid body for pressing is, for example, 0.01MPa or more and 1MPa or less. The 3 rd separating device 18 is exemplified by a screw press dehydrator (manufactured by kaiko shoji).
The oxidizing agent treatment device 19 treats the pulp fibers (mixture 98) containing the crushed superabsorbent polymer in the solid sent out from the 3 rd separation device 18 with an aqueous solution (treatment liquid) containing an oxidizing agent. Thereby, the super absorbent polymer is oxidized and decomposed and removed from the pulp fibers, and the pulp fibers not containing the super absorbent polymer are sent out together with the treatment liquid (mixed liquid 99).
The oxidizing agent treatment device includes, for example, a treatment tank and an ozone supply device when ozone is used as the oxidizing agent. The treatment tank stores an acidic aqueous solution as a treatment liquid. The ozone supply device supplies an ozone-containing gas as a gaseous substance to the treatment tank. Examples of the ozone generator of the ozone supply device include an ozone water exposure tester ED-OWX-2 manufactured by Eco designer, and an ozone generator OS-25V manufactured by Mitsubishi Motor corporation. The nozzle of the ozone supply device is disposed at the lower part of the treatment tank, and has, for example, a tubular or flat plate shape. The nozzle supplies the ozone-containing gas Z into the treatment liquid as a plurality of fine bubbles. The treatment liquid is preferably an acidic aqueous solution from the viewpoint of suppressing inactivation by ozone and inactivating the super absorbent polymer. In addition, when an acidic aqueous solution is used for the crushing treatment and the dust removal treatment, since continuity is provided between the treatments, there is no fear that the aqueous solution differs between the treatments and any trouble occurs, and the treatment can be stably and reliably performed. In addition, from the viewpoint of reducing the influence of the acid on the workers and the equipment, an organic acid is preferable, and among them, from the viewpoint of removing metals, citric acid is preferable.
Although ozone gas is used as the oxidizing agent, the present embodiment is not limited to this example, and other oxidizing agents may be used, and a liquid oxidizing agent or a solid oxidizing agent may be melted into a liquid, even if the oxidizing agent is not gaseous. Examples of the oxidizing agent include chlorine dioxide, peracetic acid, sodium hypochlorite, and hydrogen peroxide.
The 4 th separating device 20 separates pulp fibers from the treatment liquid (mixed liquid 99) containing pulp fibers treated by the oxidizing agent treatment device 19 by a screen having a plurality of openings, thereby recovering the pulp fibers to produce recycled pulp fibers.
The 4 th separation device 20 may be, for example, a screen separator. The openings of the screen (screen) are not particularly limited, and examples thereof include slits, round holes, square holes, and nets, and slits are used herein. The size (width) of the slit is a size through which pulp fibers are difficult to pass. The size of the slit is, for example, 0.2mm to 0.8mm in width. In the case of a circular hole, the size of the circular hole is, for example, 0.2mm to 0.8mm phi in diameter.
The system 1 preferably includes an ozone treatment device 22, a pH adjustment device 23, and a water storage tank 24. These apparatuses are apparatuses for regenerating and reusing the acidic aqueous solution used in the system 1. By reusing the acidic aqueous solution, the cost of the acidic aqueous solution can be reduced. The ozone treatment device 22 performs a sterilization treatment of the acidic aqueous solution 101 after further separating the super absorbent polymer from the super absorbent polymer and the acidic aqueous solution separated by the 2 nd separation device 17 with the ozone-containing aqueous solution. The pH adjusting device 23 adjusts the pH of the acidic aqueous solution 102 sterilized with the ozone-containing aqueous solution to generate a regenerated acidic aqueous solution 103. The water storage tank 24 is used for storing the remaining part of the regenerated acidic aqueous solution 103.
Next, a method of recovering pulp fibers from a used absorbent article will be described. This method is a method of recovering pulp fibers (and preferably also superabsorbent polymers) from used absorbent articles to produce recycled pulp fibers (and preferably also recycled superabsorbent polymers). Fig. 6 is a flowchart showing an example of the method according to the present embodiment. The method includes a 2 nd dust removing step S15 and a 3 rd dust removing step S16, and preferably includes a boring step S11, a crushing step S12, a 1 st separating step S13, a 1 st dust removing step S14, a 3 rd separating step S18, an oxidizing agent treating step S19, a 2 nd separating step S17, and a 4 th separating step S20. The following description will be made in detail.
The hole forming process S11 is performed by the bag breaking device 11. The collecting bag a in which the used absorbent article is enclosed is put into a solution tank V in which an acidic aqueous solution B is stored, and a hole is formed in the surface of the collecting bag a that is in contact with the acidic aqueous solution B. The acidic aqueous solution B surrounds and seals the periphery of the collection bag a so that when the collection bag a is perforated, dirt, fungus, and odor of the used absorbent article in the collection bag a are not released to the outside. When the acidic aqueous solution enters the collection bag a through the hole, the gas in the collection bag a is discharged to the outside of the collection bag a, the collection bag a has a heavier specific gravity than the acidic aqueous solution B, and the collection bag a settles in the acidic aqueous solution B. In addition, the acidic aqueous solution B inactivates the superabsorbent polymer in the used absorbent article in the collection bag a.
By deactivating the superabsorbent polymer in the used absorbent article, the water absorption capacity thereof is reduced, and the superabsorbent polymer is dehydrated and has a small particle size, so that the subsequent steps can be easily handled, and the handling efficiency can be improved. The reason why an acidic aqueous solution, i.e., an aqueous solution of an inorganic acid and an organic acid is used as the inactivation aqueous solution is that ash does not remain in the pulp fibers as compared with an aqueous solution of lime, calcium chloride, or the like, and that the degree of inactivation (particle size, specific gravity) is easily adjusted by pH. The pH of the acidic aqueous solution is preferably 1.0 or more and 4.0 or less, and more preferably 1.2 or more and 2.5 or less. If the pH is too high, the water absorption capacity of the super absorbent polymer cannot be sufficiently reduced. In addition, the sterilization ability may be lowered. If the pH is too low, the equipment may be corroded, and a large amount of alkaline chemical is required for neutralization treatment in wastewater treatment. In particular, in order to separate pulp fibers and a super absorbent polymer from other materials, it is preferable that the size and specific gravity of the pulp fibers are relatively close to those of the super absorbent polymer. Therefore, by setting the pH of the acidic aqueous solution to 1.0 or more and 4.0 or less, the superabsorbent polymer can be made smaller by inactivation, and the size and specific gravity of the pulp fiber and the size and specific gravity of the superabsorbent polymer can be made relatively close to each other. Examples of the organic acid include citric acid, tartaric acid, glycolic acid, malic acid, succinic acid, acetic acid, ascorbic acid, and the like, and hydroxycarbonate-based organic acids such as citric acid, tartaric acid, gluconic acid, and the like are particularly preferable. Metal ions and the like in excrement can be captured and removed by the chelating effect of citric acid, and a high effect of removing dirt components can be expected by the cleaning effect of citric acid. On the other hand, examples of the inorganic acid include sulfuric acid, hydrochloric acid, and nitric acid, but sulfuric acid is preferable from the viewpoints of chlorine free, cost, and the like. The pH value varies depending on the water temperature, and therefore the pH value in the present invention means a pH value measured at a temperature of 20 ℃ in an aqueous solution. The organic acid concentration of the organic acid aqueous solution is not particularly limited, but when the organic acid is citric acid, it is preferably 0.5 mass% or more and 4 mass% or less. The concentration of the inorganic acid in the aqueous solution of the inorganic acid is not particularly limited, but when the inorganic acid is sulfuric acid, it is preferably 0.1 mass% or more and 0.5 mass% or less.
For example, in the bag-breaking device 11 of fig. 2, first, a vortex is generated in the acidic aqueous solution B by the rotation of the stirring blade 33 around the rotation shaft (support shaft 32), and the collection bag a is physically and forcibly drawn in the bottom direction of the acidic aqueous solution B (solution tank V). Then, by the rotation of the bag breaking blade 41 about the rotation shaft (support shaft 42), the collection bag a moved to the bottom comes into contact with the bag breaking blade 41 to open the hole. In the case where the bag breaking blade 41 is movable in the vertical direction in the solution tank V, even if the collection bag a is not drawn in the bottom direction of the acidic aqueous solution B (solution tank V) by the vortex, the bag breaking blade 41 may be moved upward to open the hole in the collection bag a.
The crushing step S12 is performed by the crushing device 12. The acidic aqueous solution B, i.e., the mixed solution 91, contained in the collection bag a having the opening and sinking to the water surface of the acidic aqueous solution B is discharged from the solution tank V, and the used absorbent articles in the collection bag a are crushed in the acidic aqueous solution B together with the collection bag a.
For example, in the crushing apparatus 12 of fig. 2, first, the used absorbent articles in the collection bag a fed out from the solution tank V together with the acidic aqueous solution B are crushed in the acidic aqueous solution B together with the collection bag a by the crushing section 60 (in-liquid crushing step). At this time, in the crushing section 60, the mixed liquid 91 is supplied to the rotating cutter head and the liner of the biaxial crusher, which are engaged with each other and rotate inward, and the collection bag a is crushed together with the bag. Then, the acidic aqueous solution B (mixed solution 92) containing the crushed product obtained in the crushing unit 60 (in-solution crushing step) is pumped out from the crushing unit 60 by the pump 63 (pumping step), and is sent to the next step.
Here, in the crushing step S12, it is preferable to crush the used absorbent article together with the collecting bag a so that the average value of the size of the crushed material becomes 50mm to 100 mm. The absorbent article is assumed to have a length of about 150mm to 1000mm and a width of 100mm to 1000 mm. By crushing the crushed material so that the average value of the size of the crushed material is 50mm or more and 100mm or less, it is possible to reliably form slits in the back sheet and/or the front sheet of each used absorbent article. Accordingly, in each used absorbent article, the pulp fibers can be taken out from the slits with substantially no residue, and therefore, the recovery rate of the pulp fibers (total amount of regenerated pulp fibers/total amount of pulp fibers of the used absorbent article supplied) can be increased. When the average value of the sizes is less than 50mm, materials other than pulp fibers (for example, a film (a raw material of the collecting bag a, a back sheet, etc.), a nonwoven fabric (a surface sheet, etc.), an elastic body (a rubber for a leakage preventing wall, etc.)) are excessively cut, and it is difficult to separate these materials from pulp fibers in a subsequent step. As a result, foreign matter (other material) mixed into the regenerated pulp fibers increases, and the recovery rate of the pulp fibers decreases. On the other hand, if the average value of the sizes is larger than 100mm, it is difficult to form a cut in the used absorbent article. As a result, a used absorbent article in which the pulp fibers cannot be taken out is produced, and the recovery rate of the pulp fibers is lowered.
The 1 st separating step S13 is performed by the 1 st separating device 13. The mixed liquid 92 containing the crushed material and the acidic aqueous solution obtained by the crushing device 12 is stirred to wash the crushed material to remove dirt, and the mixed liquid 92 is separated into pulp fibers, a super absorbent polymer, an acidic aqueous solution, and other materials. In this case, an acidic aqueous solution may be additionally added for the purpose of enhancing the washing effect and/or for adjusting the pH. As a result, the pulp fibers, the super absorbent polymer, and the acidic aqueous solution (a part of them including other materials) in the mixed liquid 92 are separated by the through-holes and sent out from the 1 st separator 13 (mixed liquid 93). On the other hand, the materials other than the pulp fibers, the super absorbent polymer, and the acidic aqueous solution in the mixed liquid 92 cannot pass through the through-holes, and remain in the 1 st separating device 13 or are sent out through another path. A part of the other materials is not completely separated and is sent out together with the mixed liquid 93. Here, when a washing machine is used as the first separating device 13, the size of the through-hole of the washing tub functioning as a sieve is 5mm to 20mm in the case of a circular hole, and the size of the through-hole having the same area as the circular hole in the case of a hole having other shape is exemplified.
The method (system) includes at least the hole forming step S11 (bag breaking device 11) and the crushing step S12 (crushing device 12) in the crushing treatment (hole forming step S11 (bag breaking device 11) to the 1 st separating step S13 (1 st separating device 13)) for crushing the used absorbent article as described above. Therefore, the used absorbent article placed in the collecting bag is crushed in the inactivating aqueous solution together with the collecting bag, and therefore contamination of dirt, fungi, or generation of odor in the inactivating aqueous solution hardly occurs at least before the crushing is started. Further, even if dirt, fungi, or odor is mixed in the inactivated aqueous solution when the used absorbent article is crushed, the inactivated aqueous solution in which dirt or fungi are mixed is fed out from the solution tank together with the crushed material substantially simultaneously with the crushing, and therefore, the dirt or fungi can be hardly left in the solution tank and can be flowed away. Further, since the odor can be sealed with the inactivating aqueous solution, the generation of odor is also suppressed to a low level. This makes it possible to prevent dirt and fungus from scattering or to prevent odor from being emitted when the used absorbent article is crushed.
It should be noted that the used absorbent article may be crushed together with the collecting bag in a gas (for example, in the air) instead of crushing the used absorbent article together with the collecting bag in the inactivating aqueous solution (for example, an acidic aqueous solution). In this case, the punching step S11 is not required, and the crushing step S12 is performed in the air without the inactivation aqueous solution. Thereafter, the inactivated aqueous solution is supplied to the 1 st separation step S13 together with the crushed product of the crushing step S12. In the case where an acidic aqueous solution is not used as the inactivation aqueous solution, the acidic aqueous solution is added from the 1 st dust removal step S14 so that the inactivation aqueous solution containing the pulp fibers and the super absorbent polymer supplied to the 1 st dust removal step S14 becomes substantially an acidic aqueous solution.
The 1 st dust removing step S14 is performed by the 1 st dust removing device 14. The mixed liquid 93, which is the acidic aqueous solution containing pulp fibers and a super absorbent polymer and sent from the 1 st separator 13, is separated into an acidic aqueous solution containing pulp fibers and a super absorbent polymer and other materials (foreign materials) by a sieve while maintaining the pH value within a predetermined range. As a result, the pulp fibers, the super absorbent polymer, and the acidic aqueous solution (a part of them including other materials) in the mixed liquid 93 are separated by the screen and sent out from the 1 st dust removing device 14 (mixed liquid 94). On the other hand, the materials other than the pulp fibers, the super absorbent polymer, and the acidic aqueous solution in the mixed liquid 93 cannot pass through the screen and remain in the first dust removing device 14 or are sent out through another route. A part of the other materials is not completely separated and is sent out together with the mixed liquid 94.
The acidic aqueous solution is adjusted to a pH value at least before the first dust removing step S14 so that the difference between the specific gravity of the super absorbent polymer and the specific gravity of the pulp fibers and the difference between the size of the super absorbent polymer and the size of the pulp fibers are within predetermined ranges. In this case, the predetermined range is, for example, 0.2 to 5 times as large as one another. The size is for separation according to the difference in size, and the specific gravity is for separation according to the difference in specific gravity. Therefore, the step before the dust removal step S14 of 1 can be regarded as an inactivation step of inactivating the superabsorbent polymer by mixing the pulp fiber and the superabsorbent polymer with an acidic aqueous solution having a pH adjusted so that the difference between the specific gravity of the superabsorbent polymer and the specific gravity of the pulp fiber and the difference between the size of the superabsorbent polymer and the size of the pulp fiber fall within predetermined ranges.
The concentration of the pulp fibers and the super absorbent polymer in the acidic solution in the first dust removal step S14 is, for example, 0.1 mass% or more and 10 mass% or less, and preferably 0.1 mass% or more and 5 mass% or less. The ratio of pulp fibers to superabsorbent polymer in the acidic solution is, for example, 50 to 90 mass%: 50 to 10 mass%.
The 2 nd dust removing process S15 is performed by the 2 nd dust removing device 15. The mixed liquid 94, which is the acidic aqueous solution containing pulp fibers and a super absorbent polymer and is sent from the 1 st dust collector 14, is separated into the acidic aqueous solution containing pulp fibers and a super absorbent polymer and other materials (foreign materials) by a sieve while maintaining the pH within a predetermined range. As a result, the pulp fibers, the super absorbent polymer, and the acidic aqueous solution (a part of them including other materials) in the mixed liquid 94 are separated by the screen and sent out from the 2 nd dust removing device 15 (mixed liquid 95). On the other hand, the other materials in the mixed liquid 94 except the pulp fibers, the super absorbent polymer, and the acidic aqueous solution cannot pass through the screen and remain in the second dust removing device 15, or are sent out through another route. Some of the other materials are not completely separated and are sent out together with the mixed liquid 95. The acidic aqueous solution adjusts the pH so that the difference between the specific gravity of the super absorbent polymer and the specific gravity of the pulp fibers and the difference between the size of the super absorbent polymer and the size of the pulp fibers are within predetermined ranges.
The 3 rd dust removing process S16 is performed by the 3 rd dust removing device 16. The mixed liquid 95, which is the acidic aqueous solution containing pulp fibers and a super absorbent polymer and is sent from the 2 nd dust collector 15, is centrifugally separated in the inverted conical casing while maintaining the pH within a predetermined range, and is separated into pulp fibers and a super absorbent polymer in the acidic aqueous solution and other materials (foreign materials having a large weight). As a result, the pulp fibers, the super absorbent polymer, and the acidic aqueous solution in the mixed liquid 95 are sent out from the upper part of the 3 rd dust removing device 16 (cyclone) (mixed liquid 96). On the other hand, the mixed liquid 95 is fed from the lower part of the 3 rd dust removing device 16 (cyclone) with other heavy materials such as pulp fibers, super absorbent polymer, and metals other than the acidic aqueous solution. The acidic aqueous solution adjusts the pH so that the difference between the specific gravity of the super absorbent polymer and the specific gravity of the pulp fibers and the difference between the size of the super absorbent polymer and the size of the pulp fibers are within predetermined ranges.
The method (system) includes at least the 2 nd dust removal process S15 (the 2 nd dust removal device 15) and the 3 rd dust removal process S16 (the 3 rd dust removal device 16) in the dust removal processing (the 1 st dust removal process S14 (the 1 st dust removal device 14) to the 3 rd dust removal process S16 (the 3 rd dust removal device 16)) for removing foreign matters (other materials) as described above.
The 2 nd separating step S17 is performed by the 2 nd separating device 17. The mixed liquid 96, which is the acidic aqueous solution containing pulp fibers and a super absorbent polymer and is sent from the 3 rd dust collector 16, is separated into pulp fibers in the acidic aqueous solution and a super absorbent polymer in the acidic aqueous solution by a trommel. As a result, the acidic aqueous solution containing the super absorbent polymer is separated from the mixed solution 96 by passing through a trommel, and is sent out from the 2 nd separator 17. On the other hand, the acidic aqueous solution containing pulp fibers in the mixed solution 96 is not passed through the trommel, and is sent out from the 2 nd separating device 17 through another path (mixed solution 97). After that, the super absorbent polymer can be separated from the separated super absorbent polymer and acidic aqueous solution by a screen separator or the like. Therefore, the above step can be referred to as a step of separating and recovering the super absorbent polymer, and a step of producing a recycled super absorbent polymer therefrom.
The 3 rd separating step S18 is performed by the 3 rd separating device 18. The mixed liquid 97, which is the pulp fibers, the remaining superabsorbent polymer and the acidic aqueous solution that are not separated, sent from the 2 nd separator 17 is separated into a solid containing the pulp fibers and the superabsorbent polymer and a liquid containing the superabsorbent polymer and the acidic aqueous solution by a trommel. Then, the superabsorbent polymer in the solid is crushed by applying pressure while separating. The crushing is exemplified by crushing a gel-like super absorbent polymer under a pressure of gel strength or more. As a result, the acidic aqueous solution containing the super absorbent polymer is separated from the mixed solution 97 by passing through a trommel, and is sent out from the 3 rd separator 18. On the other hand, the pulp fibers crushed with the super absorbent polymer in the mixed liquid 97 cannot be fed out to the outside of the 3 rd separation apparatus 18 through the gap of the cover at the tip of the trommel without adding a trommel (mixture 98). The pressure applied to the lid is, for example, 0.01MPa or more and 1MPa or less, and preferably 0.02MPa or more and 0.5MPa or less. If the pressure is set to less than 0.02MPa, it becomes difficult to crush the super absorbent polymer, and the time for the oxidizing agent treatment cannot be shortened too much, whereas if the pressure is set to more than 0.5MPa, the super absorbent polymer is sufficiently crushed, but pulp fibers may be damaged.
The oxidizing agent treatment step S19 is performed by the oxidizing agent treatment device 19. The pulp fibers and the crushed superabsorbent polymer in the solids discharged from the 3 rd separating device 18 are treated in an aqueous solution containing an oxidizing agent. Thereby, the super absorbent polymer is oxidatively decomposed and removed from the pulp fiber. As a result, the super absorbent polymer attached to the pulp fibers (exemplified: remaining on the surfaces of the pulp fibers) of the mixture 98 is oxidatively decomposed by an aqueous solution (treatment liquid) containing an oxidizing agent (exemplified: ozone), and is removed from the pulp fibers by being changed to a low molecular weight organic material soluble in the aqueous solution. Here, the state where the super absorbent polymer is oxidatively decomposed to become a low molecular weight organic substance soluble in an aqueous solution means a state where the super absorbent polymer passes through a 2mm sieve. Thus, impurities such as super absorbent polymers contained in the pulp fibers can be removed, the pulp fibers with high purity can be produced, and sterilization, bleaching and deodorization of the pulp fibers can be performed by the treatment with the oxidizing agent.
For example, in the oxidizing agent treatment apparatus 19, the mixture 98 is fed from the upper portion of the treatment tank and settles from the upper portion toward the lower portion of the treatment liquid, that is, the aqueous solution containing the oxidizing agent. On the other hand, the ozone-containing gas is continuously discharged from the nozzle in the treatment tank into the treatment solution in the form of fine bubbles (for example, micro bubbles or nano bubbles). That is, the ozone-containing gas rises from the lower portion toward the upper portion of the treatment liquid P. In the treatment liquid, the settled pulp fibers and the ascending ozone-containing gas relatively advance and collide with each other. Then, the ozone-containing gas is attached to the surface of the pulp fibers in such a manner as to wrap the pulp fibers. At this time, ozone in the ozone-containing gas reacts with the super absorbent polymer in the pulp fibers to oxidatively decompose the super absorbent polymer, and dissolves in the treatment liquid. Thereby, the super absorbent polymer contained in the pulp fibers of the mixture 98 is oxidatively decomposed and removed from the pulp fibers.
The above-described method (system) includes at least the 3 rd separating step S18 (the 3 rd separating device 18) and the oxidizing agent treating step S19 (the oxidizing agent treating device 19) in the recovery process (the 2 nd separating step S17 (the 2 nd separating device 17) to the 4 th separating step S20 (the 4 th separating device 20)) for recovering pulp fibers and the like as described above. Therefore, by crushing the substantially spherical or block-shaped super absorbent polymer, the surface area of the super absorbent polymer can be enlarged to a large extent, and the exposed portion such as the inner portion of the super absorbent polymer being exposed to the surface side can be increased. Therefore, in the case of the block-shaped or substantially spherical super absorbent polymer in the oxidizing agent treatment step S19 (oxidizing agent treatment apparatus 19), the contact area of the super absorbent polymer with the oxidizing agent can be increased by, for example, contacting the inner portion of the super absorbent polymer that is less likely to contact the oxidizing agent with the oxidizing agent. This enables the oxidative decomposition of the super absorbent polymer to be more efficiently performed, and the time for the oxidizing agent treatment to be shortened. Thus, the efficiency of the treatment for removing the super absorbent polymer from the pulp fiber can be improved.
The 4 th separation step S20 is performed by the 4 th separation device 20, and the mixed liquid 99, which is the treatment liquid containing pulp fibers treated by the oxidizing agent treatment device 19, passes through a screen having a plurality of openings, to separate the pulp fibers and the treatment liquid from the mixed liquid 99. As a result, the treatment liquid 104 is separated from the mixed liquid 99 by passing through a sieve and sent out from the 4 th separation apparatus 20. The separated treatment liquid 104, i.e., the oxidizing agent treatment liquid, may be returned to the oxidizing agent treatment device 19 for reuse. The cost of the oxidizer treatment liquid can be reduced. On the other hand, the pulp fibers in the mixed liquid 99 cannot pass through the screen and remain in the 4 th separator 20, or are sent out through another route. The above step can also be referred to as a step of separating and recovering pulp fibers to produce recycled pulp fibers.
The specific gravity of the super absorbent polymer is measured by the pycnometer method which is a method for measuring the density and specific gravity of a chemical product according to JIS K0061. As a result, the specific gravity of the water-absorbent polymer before water absorption was 1.32 g/ml. The specific gravity was 1.04g/ml when inactivated with an aqueous citric acid solution (pH 2) and 1.01g/ml when inactivated with an aqueous citric acid solution (pH 4).
On the other hand, since the size of the super absorbent polymer (after absorbing water) is difficult to be measured, the size (diameter) of the super absorbent polymer is calculated as follows assuming that the super absorbent polymer is a sphere. That is, the average diameter of the super absorbent polymer before water absorption was set to 200 μm, and the size (diameter) of the super absorbent polymer after water absorption was estimated by volume expansion calculation from the amount of water in the aqueous solution absorbed by the super absorbent polymer. The volume expansion calculation is performed as follows. First, the amount of water absorbed by the super absorbent polymer (per 1 particle) was measured. Then, the volume of water corresponding to the amount of water is assumed to be the volume V of the super absorbent polymer after water absorption, based on V-4/3 pi r3The radius r of the super absorbent polymer after water absorption was determined. Then, the diameter 2 times the radius r was defined as the size of the super absorbent polymer (after water absorption). As a result, when the inactivation is carried out by using an aqueous citric acid solution (pH 2)The gel diameter was about 420 μm and the gel diameter was about 540 μm when inactivated with aqueous citric acid (pH 4).
The proportions of pulp fibers and superabsorbent polymer in the acidic aqueous solution were measured as follows. First, a part of an acidic aqueous solution was collected as a sample, and the sample was put into a 200-mesh filter to measure a sample weight W0. Subsequently, the sample on the filter was lifted for 5 minutes, water was drained, absolute drying was performed by a predetermined absolute drying method (method of heating at 120 ℃ for 10 minutes to dry), and the absolute dry weight W1 of the obtained absolute dried product was measured. Next, the absolute dry matter was immersed in an aqueous solution containing ozone, and the resultant was subjected to absolute drying by the above-described absolute drying method, and the absolute dry weight W2 was measured as pulp fibers. Then, the weight obtained by subtracting the absolute dry weight W2 from the absolute dry weight W1 was defined as the weight of the super absorbent polymer, and the ratio of pulp fibers to the super absorbent polymer in the acidic aqueous solution was calculated according to the following formula. That is, the ratio of (pulp fibers) is (absolute dry weight W2)/(sample weight W0), and the ratio of (superabsorbent polymer) is (absolute dry weight W1 — absolute dry weight W2)/(sample weight W0). In weight proportion, the solid weight of the soil is extremely small and therefore negligible.
Preferably, the method includes an ozone treatment step S22 and a pH adjustment step S23. These steps are steps for regenerating and recycling the acidic aqueous solution used in the method. The cost of the acidic aqueous solution can be reduced by recycling the acidic aqueous solution. The ozone treatment step S22 is a step of sterilizing the acidic aqueous solution 101 obtained by further separating the super absorbent polymer from the super absorbent polymer and the acidic aqueous solution separated in the 2 nd separation step S17 with an aqueous solution containing ozone. The pH adjustment step S23 adjusts the pH of the acidic aqueous solution sterilized with the ozone-containing aqueous solution to generate the regenerated acidic aqueous solution 103. The acidic aqueous solution 103 is supplied to the bag breaker 11, for example. Alternatively, in the case where the opening step S11 is not performed and the crushing step S12 is performed without using the inactivation solution, the separation step S13 is performed as the 1 st separation step. Alternatively, the acidic aqueous solution may be supplied to another process (apparatus) as needed. The remainder of the acidic aqueous solution 103 is stored in the water reservoir 24.
Generally, the specific gravity of a super absorbent polymer is higher than that of water, but when the super absorbent polymer absorbs water, the water absorption amount is close to the specific gravity of water. The superabsorbent polymer has a small size, but when the superabsorbent polymer absorbs water, the superabsorbent polymer increases in size according to the amount of water absorbed. In addition, the amount of water that the super absorbent polymer can absorb and hold is very large, but the amount is limited to a certain extent by performing the inactivation treatment on the super absorbent polymer. From the above, the size and specific gravity of the super absorbent polymer can be adjusted to desired values by adjusting the amount of water held by the super absorbent polymer by the degree of inactivation treatment of the super absorbent polymer. Examples of the inactivation treatment of the super absorbent polymer include a treatment of immersing the super absorbent polymer in a predetermined solution (exemplified by an acidic aqueous solution).
Therefore, the method (system) for recovering pulp fibers and superabsorbent polymer from used absorbent articles containing pulp fibers and superabsorbent polymer as described above includes at least the 2 nd dust removal step S15 (the 2 nd dust removal device 15) and the 3 rd dust removal step S16 (the 3 rd dust removal device 16) in the dust removal process (the 1 st dust removal step S14 (the 1 st dust removal device 14) to the 3 rd dust removal step S16 (the 3 rd dust removal device 16)) for removing foreign matter (other materials). The 2 nd dust removing step S15 is also a size separating step, and the 3 rd dust removing step S16 is also a specific gravity separating step. The 2 nd dust removing device 15 is also a screen separator, and the 3 rd dust removing device 16 is also a cyclone (centrifugal separator). Then, the superabsorbent polymer is inactivated in advance with an acidic aqueous solution having a pH adjusted, and the water absorption capacity of the superabsorbent polymer is adjusted so that the specific gravity and the size of the superabsorbent polymer are within predetermined ranges from those of pulp fibers (inactivation step). In this case, the predetermined range is, for example, 0.2 to 5 times as large as one another. Thus, the specific gravity and the size of the difference between the pulp fiber and the super absorbent polymer are within predetermined ranges. As a result, the pulp fibers and the super absorbent polymer can be easily separated from the other materials (mainly, resin materials) other than the pulp fibers and the super absorbent polymer in the used material of the absorbent article by the difference in size (the 2 nd dust removing step S15 (the 2 nd dust removing device 15)), and can be easily separated from the materials (mainly, metal materials) having a large specific gravity among the other materials by the difference in specific gravity (the 3 rd dust removing step S16 (the 3 rd dust removing device 16)). Then, the pulp fibers and the super absorbent polymer can be recovered from the used absorbent article by separating them from each other (the 2 nd separation step S17, the 3 rd separation step S18 (the 2 nd separation device 17, the 3 rd separation device 18)). In this case, the number of times of treatment for separating pulp fibers and super absorbent polymers from other materials can be reduced. That is, the efficiency of the process of separating the super absorbent polymer and the pulp fiber can be improved. Examples of the resin material of the used absorbent article other than pulp fibers and superabsorbent polymers include films (back sheets and the like), nonwoven fabrics (front sheets and the like), and elastomers (rubber for leakproof walls and the like). As the material having a large specific gravity among the other materials, for example, the metal material, a clip which is not originally included in the absorbent article but is mixed in when the used absorbent article is recovered, a staple of a stapler, and the like can be cited. The size of the super absorbent polymer means the particle diameter of the super absorbent polymer, and is a diameter in the case where the super absorbent polymer is spherical, and a longest width in the case of a block. The size of the pulp fibers is set to the average fiber length of the pulp fibers.
In the present embodiment, the specific gravity separation step, i.e., the 3 rd dust removal step S16 (specific gravity separation step), may preferably include a step of separating pulp fibers and superabsorbent polymers from other materials by centrifugal separation.
The difference between the specific gravity of the pulp fiber and the specific gravity of the super absorbent polymer in the present method is within a predetermined range, and therefore the pulp fiber and the super absorbent polymer can be more accurately separated from other materials (materials having a larger specific gravity, such as metal materials) by the centrifugal separation method. This can improve the efficiency of the process of separating the super absorbent polymer and the pulp fibers.
In the present embodiment, as a preferred mode, the dust removal step S15 (size separation step) 2 may include a screen separation step of separating pulp fibers and superabsorbent polymer from other materials by using a screen having a plurality of openings with a predetermined size.
In the method, the difference between the size of the pulp fibers and the size of the superabsorbent polymer is within a predetermined range, and therefore, the pulp fibers and the superabsorbent polymer can be more accurately separated from other materials (resin members, for example, films such as back sheets, nonwoven fabrics such as surface sheets, and elastomers such as rubber for leakage barriers) by passing through a screen having a plurality of openings with a predetermined size. This can improve the efficiency of the process of separating the super absorbent polymer and the pulp fibers.
In the present embodiment, as a preferred mode, the first dust removing step S14 or the coarse size separating step (the first dust removing device 14 or the coarse separator) may be included before the second dust removing step S15 or the size separating step (the second dust removing device 15 or the fine separator).
The present method (system) passes pulp fibers and super absorbent polymer and other materials through a screen having a larger plurality of openings before the dust removing process 2S 15 (dust removing device 2 15). Thus, relatively large other materials can be removed in advance. Thus, in the 2 nd dust removal step S15 (the 2 nd dust removal device 15), it is possible to suppress the screen from being clogged with relatively large other materials and to reduce the efficiency of the separation process.
In the present embodiment, as a preferable mode, the ratio of the pulp fibers and the super absorbent polymer in the acidic aqueous solution containing the inactivated super absorbent polymer may be 0.1 mass% or more and 10 mass% or less.
In the method (system), the pulp fibers and the super absorbent polymer can be more reliably separated from other materials by setting the ratio of the pulp fibers and the super absorbent polymer in the acidic aqueous solution to 0.1 mass% or more and 10 mass% or less. This can improve the efficiency of the process of separating the super absorbent polymer and the pulp fibers. However, if the amount of the super absorbent polymer and the pulp fiber to be separated is less than 0.1 mass%, the separating ability becomes wasteful, and if the amount is more than 10 mass%, the super absorbent polymer and the pulp fiber cannot be completely separated and discharged together with other materials, and in any case, the efficiency of the treatment is lowered.
In the present embodiment, as a preferable mode, the pH of the acidic aqueous solution may be 1 or more and 4 or less.
In the method (system), the pH of the acidic aqueous solution is adjusted to 1 or more and 4 or less, and therefore the specific gravity and the size of the super absorbent polymer and the specific gravity and the size of the pulp fiber can be brought closer to each other. This enables pulp fibers and superabsorbent polymers to be more reliably separated from other materials. This can improve the efficiency of the process of separating the super absorbent polymer and the pulp fibers.
In the present embodiment, the acidic aqueous solution may contain citric acid as a preferable mode.
In the method (system), since the acidic aqueous solution contains citric acid (exemplified as a concentration of 0.5 to 2.0% by mass), the super absorbent polymer can be dehydrated reliably, and the specific gravity and the size of the super absorbent polymer are set to values closer to those of pulp fibers, respectively. This enables pulp fibers and superabsorbent polymers to be more reliably separated from other materials. Further, adverse effects of the acid on the operator and corrosion of the equipment in each step can be suppressed. This can improve the efficiency of the process of separating the super absorbent polymer and the pulp fibers.
In the present embodiment, as a preferred mode, the present embodiment may further include a second separation step S17 or a polymer separation step (a second separation device 17 or a trommel separator) of separating the super absorbent polymer from the acidic aqueous solution containing the pulp fibers and the super absorbent polymer separated in the third dust removal step S16 or the specific gravity separation step (the third dust removal device 16 or the cyclone separator).
In the present method (system), other materials are removed from the pulp fibers and the super absorbent polymer, and therefore the pulp fibers and the super absorbent polymer can be easily recovered separately by separating them from each other.
The above embodiment describes a case where the structural member of the back sheet is a film and the structural member of the front sheet is a nonwoven fabric. However, the embodiment in which the structural member of the back sheet is a nonwoven fabric, the structural member of the front sheet is a film, or the embodiment in which the structural members of both the back sheet and the front sheet are films can be realized by the same method as the above-described embodiment, and the same operational effects can be produced.
The absorbent article of the present invention is not limited to the above-described embodiments, and can be appropriately combined, modified, and the like without departing from the object and spirit of the present invention.
Description of the reference numerals
S13, separation step 1 (inactivation step)
S15, dust removal step 2 (size separation step)
S16, dust removal step 3 (specific gravity separation step)
Claims (14)
1. A method for recovering pulp fibers and superabsorbent polymers from a used absorbent article comprising pulp fibers and superabsorbent polymers, wherein,
the method comprises the following steps:
an inactivation step of mixing pulp fibers and a superabsorbent polymer separated from a used absorbent article with an acidic aqueous solution having a pH adjusted so that a difference between a specific gravity of the superabsorbent polymer and a specific gravity of the pulp fibers falls within a predetermined range and a difference between a size of the superabsorbent polymer and a size of the pulp fibers falls within a predetermined range, and inactivating the superabsorbent polymer;
a size separation step of separating the pulp fibers and the superabsorbent polymer from other materials by a difference in size while maintaining the pH value within a predetermined range in the acidic aqueous solution containing the pulp fibers and the superabsorbent polymer; and
a specific gravity separation step of separating the pulp fibers and the superabsorbent polymer from other materials by a difference in specific gravity while maintaining the pH within a predetermined range in the acidic aqueous solution containing the pulp fibers and the superabsorbent polymer.
2. The method according to claim 1, wherein the specific gravity separation process comprises a process of separating the pulp fibers and the super absorbent polymer from the other materials by a centrifugal separation method.
3. The method according to claim 1 or 2, wherein the size separation process comprises a screen separation process of separating the pulp fibers and the super absorbent polymer from the other materials using a screen having a plurality of openings of a predetermined size.
4. The method according to any one of claims 1 to 3, wherein the size separation step is preceded by a coarse size separation step in which the pulp fibers and the superabsorbent polymer are separated from the other material by passing the pulp fibers and the superabsorbent polymer through a screen having a plurality of openings larger than a plurality of openings of a screen used in the size separation step while maintaining the pH value within a predetermined range in the acidic aqueous solution containing the pulp fibers and the superabsorbent polymer.
5. The method according to any one of claims 1 to 4, wherein the proportion of the pulp fibers and the superabsorbent polymer in the acidic aqueous solution formed in the inactivation step is 0.1 mass% or more and 10 mass% or less.
6. The method according to any one of claims 1 to 5, wherein the pH of the acidic aqueous solution is 1 or more and 4 or less.
7. A process according to any one of claims 1 to 6, wherein the acidic aqueous solution comprises citric acid.
8. The method according to any one of claims 1 to 7, further comprising a polymer separation step of separating the super absorbent polymer from the acidic aqueous solution containing the pulp fiber and the super absorbent polymer separated in the specific gravity separation step.
9. A system for recovering pulp fibers and superabsorbent polymer from a used absorbent article comprising pulp fibers and superabsorbent polymer, wherein,
the system comprises:
a screen separator that maintains a pH value in a predetermined range in an acidic aqueous solution containing pulp fibers and a superabsorbent polymer, in which the superabsorbent polymer has been inactivated by mixing the pulp fibers and the superabsorbent polymer separated from used absorbent articles with the acidic aqueous solution, while separating the pulp fibers and the superabsorbent polymer from other materials using a screen having a plurality of openings of a predetermined size, wherein the acidic aqueous solution adjusts the pH value in such a manner that a difference in specific gravity of the superabsorbent polymer and a difference in specific gravity of the pulp fibers are within the predetermined range and a difference in size of the superabsorbent polymer and a difference in size of the pulp fibers are within the predetermined range; and
a cyclone separator that maintains the pH value within a predetermined range in the acidic aqueous solution containing the pulp fibers and the superabsorbent polymer while separating the pulp fibers and the superabsorbent polymer from the other materials by a centrifugal separation method.
10. The system of claim 9, further comprising a coarse screen separator prior to said screen separator that maintains said pH within a predetermined range in said acidic aqueous solution comprising said pulp fibers and said superabsorbent polymer while separating said pulp fibers and said superabsorbent polymer from said other materials through a screen having a plurality of openings that are larger than said plurality of openings of a predetermined size.
11. The system according to claim 9 or 10, wherein the proportion of the pulp fibers and the superabsorbent polymer in the acidic aqueous solution containing the inactivated superabsorbent polymer is 0.1 mass% or more and 10 mass% or less.
12. The system according to any one of claims 9 to 11, wherein the pH of the acidic aqueous solution is 1 or more and 4 or less.
13. The system of any one of claims 9-12, wherein the acidic aqueous solution comprises citric acid.
14. The system according to any one of claims 9 to 13, further comprising a trommel separator for separating the superabsorbent polymer from the acidic aqueous solution containing the pulp fibers and the superabsorbent polymer separated by the cyclone separator by using a trommel.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017-212270 | 2017-11-01 | ||
| JP2017212270A JP6843030B2 (en) | 2017-11-01 | 2017-11-01 | Methods and systems for recovering pulp fibers and superabsorbent polymers from used absorbent articles |
| PCT/JP2018/028138 WO2019087485A1 (en) | 2017-11-01 | 2018-07-26 | Method and system for recovering pulp fibers and highly water-absorbent polymer from used absorbent articles |
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| CN111263670A true CN111263670A (en) | 2020-06-09 |
| CN111263670B CN111263670B (en) | 2022-06-28 |
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| JP (1) | JP6843030B2 (en) |
| KR (1) | KR102559361B1 (en) |
| CN (1) | CN111263670B (en) |
| AU (1) | AU2018360432B2 (en) |
| BR (1) | BR112020008506B1 (en) |
| PH (1) | PH12020550527A1 (en) |
| RU (1) | RU2020117217A (en) |
| WO (1) | WO2019087485A1 (en) |
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| JP6771633B1 (en) | 2019-05-30 | 2020-10-21 | ユニ・チャーム株式会社 | A method for regenerating a super absorbent polymer derived from a used absorbent article and a recycled superabsorbent polymer derived from a used absorbent article |
| JP7361597B2 (en) * | 2019-12-20 | 2023-10-16 | ユニ・チャーム株式会社 | Method for separating and recovering pulp fibers and superabsorbent polymers from a mixture thereof, and use of a separation solution for separating and recovering them from a mixture of pulp fibers and superabsorbent polymers |
| JP7362886B2 (en) | 2020-02-14 | 2023-10-17 | 株式会社日本触媒 | How to recycle water absorbent resin |
| WO2022091975A1 (en) * | 2020-10-30 | 2022-05-05 | 三洋化成工業株式会社 | Method for dehydration treatment of water-absorbent resin particles |
| EP4219034A1 (en) * | 2020-11-04 | 2023-08-02 | Unicharm Corporation | Separation method |
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- 2017-11-01 JP JP2017212270A patent/JP6843030B2/en active Active
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2018
- 2018-07-26 AU AU2018360432A patent/AU2018360432B2/en active Active
- 2018-07-26 WO PCT/JP2018/028138 patent/WO2019087485A1/en active Application Filing
- 2018-07-26 BR BR112020008506-5A patent/BR112020008506B1/en active IP Right Grant
- 2018-07-26 KR KR1020207002979A patent/KR102559361B1/en active IP Right Grant
- 2018-07-26 RU RU2020117217A patent/RU2020117217A/en unknown
- 2018-07-26 CN CN201880068643.6A patent/CN111263670B/en active Active
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- 2020-04-30 PH PH12020550527A patent/PH12020550527A1/en unknown
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| JP2013150976A (en) * | 2011-12-28 | 2013-08-08 | Nippon Paper Industries Co Ltd | Method for treating used sanitary article |
| CN104411881A (en) * | 2012-07-06 | 2015-03-11 | 日本制纸株式会社 | Recycled fiber and recycled fiber molding |
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| Publication number | Publication date |
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| RU2020117217A3 (en) | 2021-12-07 |
| RU2020117217A (en) | 2021-12-01 |
| BR112020008506B1 (en) | 2021-12-14 |
| CN111263670B (en) | 2022-06-28 |
| PH12020550527A1 (en) | 2021-04-26 |
| AU2018360432B2 (en) | 2022-10-20 |
| KR20200076664A (en) | 2020-06-29 |
| BR112020008506A2 (en) | 2020-10-06 |
| JP2019084470A (en) | 2019-06-06 |
| AU2018360432A1 (en) | 2020-05-14 |
| KR102559361B1 (en) | 2023-07-25 |
| JP6843030B2 (en) | 2021-03-17 |
| WO2019087485A1 (en) | 2019-05-09 |
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