Method and apparatus for recycling absorbent materials

Abstract

To obtain a high-quality recycled product from an unused absorbent article.SOLUTION: An absorbent article recycling method includes: a solvent treatment step (step S1) for immersing an unused absorbent article (target 110), where sheets 20 containing pulp fiber 11 and SAP 12 as absorbers 10 are bonded with an adhesive, in a solvent 120, to dissolve the adhesive in the solvent 120; a separation recovery step (step S2) for separating the absorbent article (target 110) from which the adhesive has been dissolved and removed, into the sheets 20 and the pulp fiber 11, and the SAP12, to recover them separately; and a drying step (step S3) for drying the separated and recovered constituent materials, which are the sheets 20 and the pulp fiber 11, and the SAP12.SELECTED DRAWING: Figure 2

Description

Technical Field

[0003]

[0001] The present invention relates to a method and an apparatus for recycling unused absorbent articles such as out-of-spec products (defective products) and chips (cut ends) generated in the manufacturing process of absorbent articles such as paper diapers, sanitary napkins, etc. In particular, it relates to a method and an apparatus for recycling unused absorbent articles that can obtain high-quality recycled products.

Background Art

[0002] In the manufacturing process of absorbent articles such as paper diapers, sanitary napkins, incontinence pads, pantiliners, pet sheets, etc., defects such as breakage, dirt, poor adhesion, folding, misalignment or lack of constituent materials may occur, or there may be seams, fold lines, wrinkles, etc. that are not assumed in the design on sheets or tapes, or the amount of pulp fibers or superabsorbent polymer (SAP) may not meet the predetermined standards, resulting in out-of-spec products (defective products). In particular, since such absorbent articles are used in delicate areas, they are strictly inspected to ensure safety and security, and it is widely practiced to prevent out-of-spec products (defective products) from entering the market. Therefore, the amount of defective products generated in the manufacturing process cannot be ignored. Also, in the manufacturing process of mass-producing absorbent articles, the outside of the absorbent body containing pulp fibers and superabsorbent polymer is covered with a plurality of layers of sheets of a predetermined size, then heat-sealed into small portions of the product size, and trimmed and cut into individual products, resulting in chips (cut ends).

[0003] ​While it is known that such substandard products and scraps can be crushed and thermally recycled into solid fuel (Refuse-derived paper and plastics densified fuel: RPF), absorbent materials contain a large amount of superabsorbent polymers. These polymers absorb moisture and water, resulting in RPF derived from absorbent materials having a high moisture content and low calorific value. Furthermore, the swelling caused by the absorption of water by the superabsorbent polymers increases the volume of RPF derived from absorbent materials, and in some cases, it can even decompose and disintegrate. Furthermore, if the cooling process during the RPF conversion is insufficient, or if the swollen and gelled superabsorbent polymer reacts with surrounding organic matter, it can accumulate heat, potentially emitting foul odors or even igniting. In addition, the swelling caused by the absorption of water by the superabsorbent polymer increases the volume and weight of the RPF, requiring more space for transportation and storage, thus increasing the burden of securing storage space and handling transportation. Furthermore, because the superabsorbent polymer is minute, it is prone to falling off even after being converted into RPF, and it has been pointed out that this can cause workers to slip and fall during transportation and storage. Therefore, even when unused absorbent materials such as off-spec products and chips were crushed and converted into RPF (Refuse Derived Fuel), the energy consumption during transportation and incineration was high, and the resulting material was not necessarily of sufficient quality to be used as fuel.

[0004] Here, in the case of used absorbent articles, it is known that swelling due to water absorption can be suppressed by immersing the superabsorbent polymer in an aqueous solution containing an inactivating agent such as calcium chloride, thereby replacing the sodium salt of the superabsorbent polymer with divalent metal ions such as calcium salts, shrinking and dehydrating the swollen gel of the superabsorbent polymer and inactivating it. However, if such an inactivation treatment of the superabsorbent polymer is performed when converting it into RPF, the quality as a fuel will decrease because the amount of foreign matter that hinders combustion, such as chlorine and ash, will increase.

[0005] On the other hand, Patent Documents 2 to 5 propose that off-spec products and the like generated during the manufacturing of absorbent articles be crushed to separate and recover their constituent materials for recycling. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-124711 [Patent Document 2] Japanese Patent Publication No. 2001-336077 [Patent Document 3] International Publication No. 2017 / 104062 [Patent Document 4] Japanese Patent Publication No. 2007-175591 [Patent Document 5] Japanese Patent Publication No. 2022-15986 [Overview of the project] [Problems that the invention aims to solve]

[0007] In the prior art described in Patent Documents 2 to 4, the pulp fibers and granular superabsorbent polymer embedded between the front and back sheets are extracted by crushing, cutting, or applying physical impact or mechanical cutting force to off-spec absorbent articles and scraps. However, when crushing or cutting is performed, the crushed pieces (cut pieces, shredded pieces) harden because adhesives (hot melt adhesives) are used to bond the constituent materials of the absorbent article, making it difficult to separate the constituent materials and requiring a great deal of effort and energy to separate and recover them. In particular, separating the parts where the materials have solidified by crushing, defibrating, etc., requires a large amount of energy, and this large amount of energy also causes the granular superabsorbent polymer to become finer and powdery. As a result, even if the superabsorbent polymer is recovered, the recovery rate is low, and its original properties are altered, making it unsuitable for recycling as an absorbent material in absorbent articles. In other words, when superabsorbent polymers are granulated or powdered, their water absorption properties decrease, and if the particle size becomes too small, they are more likely to be exposed on the outside of the product when recycled as absorbent material in absorbent articles, thus lowering the quality of the absorbent article. Therefore, recycling them as absorbent material in absorbent articles has been difficult. In addition, if fine particles of superabsorbent polymer are released into wastewater, there is also the problem of the burden on wastewater treatment.

[0008] Therefore, the object of the present invention is to provide a method and apparatus for recycling absorbent articles that can obtain high-quality recycled products from unused absorbent articles. [Means for solving the problem]

[0009] The method for recycling absorbent articles according to claim 1 involves, in a solvent treatment step, immersing an unused absorbent article, which consists of pulp fibers and a superabsorbent polymer as absorbents surrounded by a sheet and the sheet joined with an adhesive, in a solvent to dissolve the adhesive in the solvent; in a separation and recovery step, separating and recovering the absorbent article, which has been dissociated by the dissolution of the adhesive in the solvent, into the superabsorbent polymer, the pulp fibers, and the sheet; and in a drying step, drying the constituent materials of the absorbent article from which the adhesive has been dissolved and removed.

[0010] The above solvent treatment process involves immersing an absorbent article, which is formed by surrounding an absorbent material containing pulp fibers and a superabsorbent polymer with a sheet and joining the sheets with an adhesive, in a solvent to dissolve and remove the adhesive from the absorbent article using the solvent. The above separation and recovery process involves separating and recovering the absorbent material dissociated by dissolving and removing the adhesive into at least a sheet and pulp fibers and a superabsorbent polymer. For example, the constituent materials are separated by utilizing differences in dimensions, specific gravity, etc. The above drying process involves drying the constituent materials of the absorbent article that have been dissociated by the dissolution and removal of the adhesive, thereby volatilizing and removing the attached solvent. The above separation and recovery step and drying step may be configured such that the separation and recovery step is provided after the solvent treatment step, and the drying step is provided after the separation and recovery step, or the drying step is provided after the solvent treatment step, and the separation and recovery step is provided after the drying step.

[0011] Here, the absorbent article is, for example, an article used to absorb liquids discharged from a person or animal, such as a disposable diaper, sanitary napkin, incontinence pad, panty liner, or pet sheet, and is formed by, for example, enclosing an absorbent body containing pulp fibers and a superabsorbent polymer with a sheet and joining the opposing sheets together with a hot melt adhesive. Furthermore, the unused absorbent materials mentioned above refer to loss items such as off-spec products (defective products) and trimmed scraps (cut edges) that are generated during the manufacturing process of absorbent materials such as disposable diapers. Furthermore, the above-mentioned solvent can be any solvent capable of dissolving the hot-melt adhesive used in absorbent articles. Preferably, a halogenated hydrocarbon solvent such as a petroleum-based solvent containing paraffin, naphthene, etc., or a chlorine-based solvent such as tetrachloroethylene or trichloroethylene is used.

[0012] Claim 1The solvent used to dissolve the adhesive in the absorbent article in the method for recycling the absorbent article of the invention is preferably a petroleum-based and / or halogenated hydrocarbon-based dry cleaning solvent. As the above-mentioned petroleum-based solvent, petroleum-based solvents containing paraffin, naphthenes, etc., which are used as dry cleaning solvents are preferred. Furthermore, as the halogenated hydrocarbon solvent mentioned above, chlorine-based solvents such as tetrachloroethylene and trichloroethylene are preferred.

[0013] Claim 2 The solvent used to dissolve the adhesive of the absorbent article in the method for recycling the absorbent article of the invention is preferably one whose specific gravity is in the range of 0.7 to 1.5, and more preferably one in the range of 0.7 to 0.8. As solvents with a specific gravity of 0.7 or higher and 1.5 or lower, for example, petroleum-based solvents containing paraffin, naphthenes, etc., which are used as dry cleaning solvents, can be used.

[0014] Claim 3 The solvent used to dissolve the adhesive in the absorbent article in the method for recycling absorbent articles of the invention has a specific gravity within the range of 1.6 or more and 1.8 or less. As solvents with a specific gravity of 1.6 or higher and 1.8 or lower, for example, chlorine-based halogenated hydrocarbon solvents such as tetrachloroethylene, which are used as dry cleaning solvents, can be used.

[0015] Claim 4 The separation and recovery step of the invention's method for recycling absorbent articles involves separating the absorbent article into the superabsorbent polymer, the sheet, and the pulp fibers in the solvent into which the absorbent article has been immersed. The constituent materials of the absorbent article, which have been dismantled in the solvent in which the adhesive has been dissolved, are separated using gravity, centrifugal force, specific gravity difference, and filtration separation using a screen or the like.

[0016] Claim 5The recycling method of the absorbent article of the invention further distills the solvent in which the adhesive is dissolved in the adhesive separation and recovery step, and separates and recovers the adhesive from the solvent. The above adhesive separation and recovery step is a step of separating and recovering the adhesive from the solvent by depositing the adhesive by distilling the solvent in which the adhesive is dissolved by immersing the absorbent article.

[0017] Claim 6 The recycling method of the absorbent article of the invention recovers the solvent from which the adhesive has been separated, and reuses it as the solvent for immersing the absorbent article in the solvent treatment step. The distilled solvent gas is cooled and liquefied, and then preferably purified by filter filtration and reused.

[0018] Claim 7 The recycling method of the absorbent article of the invention further includes a solid fuel conversion step of converting the remaining sheet and the pulp fibers from which the superabsorbent polymer has been separated into solid fuel (RPF conversion). The above solid fuel conversion step is a step of solidifying the constituent material including the remaining sheet and the pulp fibers from which the superabsorbent polymer has been separated by compression molding and cooling after a drying step to form solidified fuel.

[0019] Claim 8 The recycling apparatus for the absorbent article of the invention immerses an unused absorbent article formed by surrounding pulp fibers and a superabsorbent polymer as an absorber with a sheet and joining the sheet with an adhesive in a solvent to dissolve the adhesive in the solvent, and separates and recovers the absorbent article dissociated by the dissolution of the adhesive in the solvent into the superabsorbent polymer, the pulp fibers and the sheet by separation and recovery means, and dries the constituent material of the absorbent article from which the adhesive has been dissolved and removed by drying means.

[0020] The above-mentioned solvent treatment method involves immersing an absorbent article, which is formed by surrounding an absorbent material containing pulp fibers and a superabsorbent polymer with a sheet and joining the sheets with an adhesive, in a solvent to dissolve and remove the adhesive from the absorbent article using the solvent. The above separation and recovery means separates and recovers the absorbent article dissociated by dissolving and removing the adhesive into at least a sheet and pulp fibers and a superabsorbent polymer. For example, the constituent materials are separated by utilizing differences in dimensions, specific gravity, etc. The above drying method involves removing the solvent adhering to the constituent materials of the absorbent article, which has been dissociated by the dissolution and removal of the adhesive, by vacuum drying, hot air drying, etc., thereby volatilizing the solvent. The above-mentioned separation and recovery means and drying means may be used to separate and recover the constituent materials of the absorbent article that have been dissociated by the dissolution and removal of the adhesive using the separation and recovery means, and then dry them using the drying means, or to dry the constituent materials of the absorbent article that have been dissociated by the dissolution and removal of the adhesive using the drying means, and then separate and recover them using the separation and recovery means.

[0021] Here, the absorbent article is, for example, an article used to absorb liquids discharged from a person or animal, such as a disposable diaper, sanitary napkin, incontinence pad, panty liner, or pet sheet, and is formed by, for example, enclosing an absorbent body containing pulp fibers and a superabsorbent polymer with a sheet and joining the opposing sheets together with a hot melt adhesive. Furthermore, the unused absorbent materials mentioned above refer to loss items such as off-spec products (defective products) and trimmed scraps (cut edges) that are generated during the manufacturing process of absorbent materials such as disposable diapers. Furthermore, the above-mentioned solvent can be any solvent capable of dissolving the hot-melt adhesive used in absorbent articles. Preferably, a halogenated hydrocarbon solvent such as a petroleum-based solvent containing paraffin, naphthene, etc., or a chlorine-based solvent such as tetrachloroethylene or trichloroethylene is used.

[0022] Claim 8The solvent used to dissolve the adhesive of the absorbent article in the absorbent article recycling apparatus of the invention is preferably a petroleum-based and / or halogenated hydrocarbon-based dry cleaning solvent. As the above-mentioned petroleum-based solvent, petroleum-based solvents containing paraffin, naphthenes, etc., which are used as dry cleaning solvents are preferred. Furthermore, as the halogenated hydrocarbon solvent mentioned above, chlorine-based solvents such as tetrachloroethylene and trichloroethylene are preferred.

[0023] Claim 9 The solvent used to dissolve the adhesive of the absorbent article in the absorbent article recycling device of the invention is preferably one whose specific gravity is in the range of 0.7 to 1.5, and more preferably one in the range of 0.7 to 0.8. As solvents with a specific gravity of 0.7 or higher and 1.5 or lower, for example, petroleum-based solvents containing paraffin, naphthenes, etc., which are used as dry cleaning solvents, can be used.

[0024] Claim 10 The solvent used to dissolve the adhesive of the absorbent article in the recycling device for absorbent articles of the invention has a specific gravity within the range of 1.6 or more and 1.8 or less. As solvents with a specific gravity of 1.6 or higher and 1.8 or lower, for example, chlorine-based halogenated hydrocarbon solvents such as tetrachloroethylene, which are used as dry cleaning solvents, can be used.

[0025] Claim 11 The separation and recovery means of the absorbent article recycling apparatus of the invention separates the absorbent article into the sheet and pulp fibers and the superabsorbent polymer in the solvent into which the absorbent article is immersed. The constituent materials of the absorbent article, which have been dismantled in the solvent in which the adhesive has been dissolved, are separated using gravity, centrifugal force, specific gravity difference, etc., and filtration separation using a screen or the like.

[0026] Claim 12The invention further includes an absorbent article recycling device which uses an adhesive separation and recovery means to distill the solvent in which the adhesive is dissolved, thereby separating and recovering the adhesive from the solvent. The above adhesive separation and recovery means separates and recovers the adhesive from the solvent by distilling the solvent in which the adhesive has been dissolved by immersing an absorbent article, thereby precipitating the adhesive.

[0027] Claim 13 The invention of the absorbent article recycling device involves returning the solvent, from which the adhesive has been separated by a solvent circulation path, to the solvent treatment section and reusing it as a solvent for immersion treatment of the absorbent article. The distilled solvent gas is cooled, liquefied, and then preferably purified by filter filtration before being reused.

[0028] Claim 14 The invention of the absorbent article recycling apparatus further comprises a means for converting the remaining sheet and pulp fibers, from which the superabsorbent polymer has been separated, into solid fuel. The above-described means for producing solid fuel comprises a molding machine for drying and then compressing the constituent material, which includes the sheet and pulp fibers remaining after the superabsorbent polymer has been separated, and a cooling machine for cooling after molding, thereby solidifying the sheet and pulp fibers to produce solid fuel. [Effects of the Invention]

[0029] According to the method for recycling absorbent articles of the invention of claim 1, in a solvent treatment step, an unused absorbent article, which is made by joining sheets containing an absorbent material with an adhesive, is immersed in a solvent to dissolve the adhesive in the solvent. Then, in a separation and recovery step, the superabsorbent polymer, the pulp fibers, and the sheet of the absorbent article from which the adhesive has been dissolved and removed are separated and recovered. In a drying step, the constituent materials of the absorbent article from which the adhesive has been dissolved and removed are dried.

[0030] In this method, the adhesive joining the components of unused absorbent articles is dissolved in a solvent and removed from the absorbent articles, thereby dismantling the absorbent articles and separating and recovering the superabsorbent polymer, pulp fibers, and sheets. As the adhesive is dissolved and removed from the absorbent articles, the absorbent articles are easily decomposed, and the separation of the superabsorbent polymer, pulp fibers, and sheets becomes easy. Therefore, it is possible to improve the recovery rate of the superabsorbent polymer. In particular, by removing the adhesive from the absorbent articles, the superabsorbent polymer, pulp fibers, and sheets can be accurately separated and recovered without adding a large amount of energy that would cause the superabsorbent polymer to become finely granulated or pulverized. The separated and recovered pulp fibers and sheets, having been separated from the superabsorbent polymer and having the adhesive removed, are of high quality when converted into solid fuel, with less impurities such as moisture, salt, and ash, resulting in a higher calorific value. Furthermore, the superabsorbent polymer separated from the pulp fibers and sheets can be separated and recovered while maintaining its original properties as an absorbent material in absorbent articles, without being pulverized or powdered. In addition, since the adhesive is removed, it is suitable for material recycling and also suitable for recycling as an absorbent material in absorbent articles. In this way, high-quality recycled products can be obtained from unused absorbent materials.

[0031] Claim 1 According to the invention of the method for recycling absorbent articles, since the solvent is a petroleum-based and / or halogenated hydrocarbon-based dry cleaning solvent, it is less susceptible to oxidative degradation and suitable for repeated reuse, and the solvent odor is less likely to remain in the separated and recovered superabsorbent polymer. Therefore , low It can be made more cost-effective, and the separated and recovered superabsorbent polymer can be recycled for a wide range of uses.

[0032] Claim 2According to the method for recycling absorbent articles based on the invention, the solvent used to immerse the absorbent article has a specific gravity in the range of 0.7 to 1.5, so the superabsorbent polymer settles in the solvent after the absorbent article has been immersed in it. Therefore, the sheet and pulp fibers and the superabsorbent polymer can be accurately separated in the solvent by filtration separation using a screen or the like under low load conditions and with energy savings. Thus, in addition to the effects described in claim 1, the superabsorbent polymer can be recovered in high quality at low cost and with energy savings, and the recovery rate can be improved, as the sheet and pulp fibers and the superabsorbent polymer can be accurately separated under low cost, energy savings, and low load conditions.

[0033] Claim 3 According to the method for recycling absorbent articles based on the invention, the solvent used to immerse the absorbent article has a specific gravity in the range of 1.6 to 1.8, so the superabsorbent polymer floats in the solvent after the absorbent article has been immersed in it. Therefore, the sheet and pulp fibers and the superabsorbent polymer can be accurately separated in the solvent by filtration separation using a screen or the like under low load conditions and with energy savings. Thus, in addition to the effects described in claim 1, the superabsorbent polymer can be recovered in high quality at low cost and with energy savings, and the recovery rate can be improved, as the sheet and pulp fibers and the superabsorbent polymer can be accurately separated under low cost, energy savings, and low load conditions.

[0034] Claim 4According to the method for recycling absorbent articles of the invention, the separation and recovery step involves separating the absorbent article into a sheet and pulp fibers and a superabsorbent polymer in the solvent in which the absorbent article is immersed. This separation of the constituent materials of the absorbent article, which has been dismantled in the solvent in which the adhesive has been dissolved, is achieved by using gravity, centrifugal force, specific gravity difference, and filtration separation using a screen or the like to separate the sheet and pulp fibers and the superabsorbent polymer. Therefore, because the separation is wet, the sheet and pulp fibers and the superabsorbent polymer can be separated accurately under low-impact and energy-saving conditions. Consequently, in addition to the effects described in claim 1, the superabsorbent polymer can be recovered in high quality at low cost and energy-saving conditions, and the recovery rate can be improved.

[0035] Claim 5 According to the invention of the method for recycling absorbent articles, the method further includes an adhesive separation and recovery step of evaporating the solvent in which the adhesive has dissolved and separating and recovering the adhesive. Therefore, in addition to the effects described in claim 1, the adhesive of the absorbent article can be recycled, and resources can be utilized more effectively.

[0036] Claim 6 According to the method for recycling absorbent articles of the invention, the solvent separated from the adhesive in the adhesive separation and recovery step is reused as a solvent for immersing the absorbent article in the solvent treatment step, therefore, 5 In addition to the effects described above, it can reduce environmental impact and lower costs.

[0037] Claim 7 According to the method for recycling absorbent articles of the invention, the sheet and pulp fibers remaining after the superabsorbent polymer has been separated in the solid fuel production process are converted into solid fuel. As a result, the resulting solid fuel does not swell due to the separation of the superabsorbent polymer, and furthermore, because the adhesive has also been removed, it has less impurities such as moisture, salt, and ash, and therefore has a high calorific value. Thus, in addition to the effects described in claim 1, a high-quality solid fuel can be obtained.

[0038] Claim 8 According to the absorbent article recycling apparatus of the invention, in the solvent treatment section, unused absorbent articles, which are made by joining sheets enclosing an absorbent material with an adhesive, are immersed in a solvent to dissolve the adhesive in the solvent, the absorbent article from which the adhesive has been dissolved and removed is separated and recovered by a separation means into the sheet, the pulp fibers, and the superabsorbent polymer, and the constituent materials of the absorbent article from which the adhesive has been dissolved and removed are dried by a drying means.

[0039] In this method, the adhesive joining the components of unused absorbent articles is dissolved in a solvent and removed from the absorbent articles, thereby dismantling the absorbent articles and separating and recovering the superabsorbent polymer, pulp fibers, and sheets. As the adhesive is dissolved and removed from the absorbent articles, the absorbent articles are easily decomposed, and the separation of the superabsorbent polymer, pulp fibers, and sheets becomes easy. Therefore, it is possible to improve the recovery rate of the superabsorbent polymer. In particular, by removing the adhesive from the absorbent articles, the superabsorbent polymer, pulp fibers, and sheets can be accurately separated and recovered without adding a large amount of energy that would cause the superabsorbent polymer to become finely granulated or pulverized. The separated and recovered pulp fibers and sheets, having been separated from the superabsorbent polymer and having the adhesive removed, are of high quality when converted into solid fuel, with less impurities such as moisture, salt, and ash, resulting in a higher calorific value. Furthermore, the superabsorbent polymer separated from the pulp fibers and sheets can be separated and recovered while maintaining its original properties as an absorbent material in absorbent articles, without being pulverized or powdered. In addition, since the adhesive is removed, it is suitable for material recycling and also suitable for recycling as an absorbent material in absorbent articles. In this way, high-quality recycled products can be obtained from unused absorbent materials.

[0040] Claim 8According to the invention of the absorbent article recycling device, the solvent is a petroleum-based and / or halogenated hydrocarbon-based dry cleaning solvent, making it less susceptible to oxidative degradation and suitable for repeated reuse, and also less likely to leave a solvent odor on the separated and recovered constituent materials. Therefore , low It can be made more cost-effective, and the separated and recovered superabsorbent polymer can be recycled for a wide range of uses.

[0041] Claim 9 According to the invention of the absorbent article recycling device, the solvent used to immerse the absorbent article has a specific gravity in the range of 0.7 to 1.5, so the superabsorbent polymer settles in the solvent after the absorbent article has been immersed in it. Therefore, the sheet and pulp fibers and the superabsorbent polymer can be accurately separated in the solvent by filtration separation using a screen or the like under low load conditions and with energy savings. Thus, the claim is made possible by being able to accurately separate the sheet and pulp fibers and the superabsorbent polymer under low cost, energy savings, and low load conditions. 8 In addition to the effects described above, it is possible to recover highly absorbent polymers in a high-quality manner at low cost and with energy savings, and to improve the recovery rate.

[0042] Claim 10 According to the invention of the absorbent article recycling device, the solvent used to immerse the absorbent article has a specific gravity in the range of 1.6 to 1.8, so the superabsorbent polymer floats in the solvent after the absorbent article has been immersed in it. Therefore, the sheet and pulp fibers and the superabsorbent polymer can be accurately separated in the solvent by filtration separation using a screen or the like under low load conditions and with energy savings. Thus, the claim is made possible by being able to accurately separate the sheet and pulp fibers and the superabsorbent polymer under low cost, energy savings, and low load conditions. 8 In addition to the effects described above, it is possible to recover highly absorbent polymers in a high-quality manner at low cost and with energy savings, and to improve the recovery rate.

[0043] Claim 11According to the invention of the absorbent article recycling device, the separation and recovery means separates the sheet and pulp fibers of the absorbent article from the superabsorbent polymer in the solvent into which the absorbent article is immersed. Therefore, the constituent materials of the absorbent article, which have been dismantled in the solvent in which the adhesive has been dissolved, are separated into the sheet and pulp fibers and the superabsorbent polymer by using gravity, centrifugal force, specific gravity difference, etc., and filtration separation using a screen, etc. Therefore, since the separation is wet, the sheet and pulp fibers and the superabsorbent polymer can be separated accurately under low load conditions and energy saving conditions. Thus, the claim is made possible by being able to separate the sheet and pulp fibers and the superabsorbent polymer accurately under low cost, energy saving, and low load conditions. 8 In addition to the effects described above, it is possible to recover highly absorbent polymers in a high-quality manner at low cost and with energy savings, and to improve the recovery rate.

[0044] Claim 12 According to the invention of the absorbent article recycling device, the device further comprises an adhesive separation and recovery means for evaporating the solvent in which the adhesive has dissolved and separating and recovering the adhesive, thus, 8 In addition to the effects described above, the adhesives used in absorbent materials can be recycled, allowing for more efficient use of resources.

[0045] Claim 13 According to the invention of the absorbent article recycling device, the device includes a solvent circulation path that allows the solvent separated from the adhesive by the adhesive separation and recovery means to be reused as a solvent for immersing the absorbent article in the solvent treatment section, therefore, 12 In addition to the effects described above, it can reduce environmental impact and lower costs.

[0046] Claim 14 According to the absorbent article recycling apparatus of the invention, the sheet and pulp fibers remaining after the superabsorbent polymer has been separated in the solid fuel conversion process are converted into solid fuel. As a result, the obtained solid fuel does not swell due to the separation of the superabsorbent polymer, and furthermore, because the adhesive has also been removed, it has less impurities such as moisture, salt, and ash, and therefore has a high calorific value.8 In addition to the effects described above, high-quality solid fuel can be obtained. [Brief explanation of the drawing]

[0047] [Figure 1] Figure 1 is an explanatory diagram illustrating the constituent materials of a diaper, which is an example of an absorbent article. [Figure 2] Figure 2 is a flowchart showing the recycling method for absorbent articles according to this embodiment. [Figure 3] Figure 3 is a conceptual diagram illustrating Example 1 of the method and apparatus for recycling absorbent articles according to this embodiment. [Figure 4] Figure 4 is a schematic diagram illustrating the separation and recovery process and separation and recovery means of Example 1 of the method for recycling absorbent articles and the recycling apparatus according to this embodiment. [Figure 5] Figure 5 is a conceptual diagram illustrating Example 2 of the method and apparatus for recycling absorbent articles according to this embodiment. [Figure 6] Figure 6 is a schematic diagram illustrating the separation and recovery process and separation and recovery means of Example 2 of the method for recycling absorbent articles and the recycling apparatus according to this embodiment. [Modes for carrying out the invention]

[0048] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments and their modifications, the same symbols and reference numerals represent the same or corresponding functional parts, and the same symbols and reference numerals in the embodiments and modifications represent functional parts common to those embodiments and modifications; therefore, redundant detailed explanations are omitted here.

[0049] [Embodiment] First, the absorbent articles to be recycled in this embodiment will be described with reference to Figure 1. Absorbent articles such as disposable diapers, sanitary napkins, incontinence (urine absorption) pads, panty liners, and pet sheets mainly consist of an absorbent body 10 made of pulp fibers 11 and a super absorbent polymer 12 (SAP), which is wrapped in sheets 20 such as a surface sheet 21 and a back sheet 22 made of nonwoven fabric or thermoplastic resin film, and the opposing surface sheet 21 and back sheet 22 are joined together with a hot melt adhesive.

[0050] The absorbent body 10, which is placed between the surface sheet 21 and the back sheet 22, is composed of pulp fibers 11 and superabsorbent polymer (SAP) 12 as absorbent materials. As pulp fibers 11 (fibrous pulp), mainly cellulosic fibers such as wood pulp (coniferous pulp, hardwood pulp), cross-linked pulp, non-wood pulp, regenerated cellulose, semi-synthetic cellulose, cellulose nanofiber (CNF), cellulose acetate, rayon, and cotton are used, but synthetic fibers may also be included, and are used in the absorbent body 10 in the form of fluff pulp (cotton-like pulp), which is a chemical pulp. The fiber length is on average a few millimeters, for example about 1 mm to 5 mm, and the fiber diameter is on average a few tens of micrometers, for example about 10 to 50 micrometers.

[0051] Furthermore, the superabsorbent polymer (hereinafter referred to as "SAP") 12 is a hydrophilic polymer (water-soluble polymer) with a crosslinked structure, such as a synthetic polymer system including polyacrylates (e.g., sodium polyacrylate), polysulfonates, polyvinyl alcohols, polyacrylamides, polyoxyethylenes, polyaspartates, polyglutamates, polyalginates, maleate anhydrides, starches, celluloses, and amino acids. For example, sodium polyacrylate, carboxymethylcellulose (CMC), starch-acrylic acid (salt) graft copolymer, saponified starch-acrylonitrile copolymer, crosslinked sodium carboxymethylcellulose, polyvinyl alcohol (PVA), and PVA / sodium polyacrylate are used, but typically polymers or copolymers of acrylic acid or alkali metal acrylate salts are used. Usually, particulate form is used as a water-swellable, water-insoluble polymer gelling agent, but it may also be fibrous. The particle size of particulate SAP in its dry state is, for example, about 150 to 600 μm.

[0052] The surface sheet (top sheet) 21 is a surface material, and for example, nonwoven fabric or film is used. Specifically, liquid-permeable nonwoven fabric, synthetic resin film, or laminates (composite sheets) thereof are used. Furthermore, the back sheet 22 is a waterproofing material, and for example, a porous polyolefin resin or other synthetic resin film containing fillers (inorganic fillers such as calcium carbonate, barium sulfate, magnesium oxide, barium carbonate, talc, silica, kaolin, mica, clay, titanium dioxide, zinc oxide, pigments, etc.) and having fine pores is used. In other words, a synthetic resin film that does not allow liquid to pass through and is breathable and moisture permeable, or a synthetic resin film that is not breathable is used.

[0053] Examples of nonwoven fabrics used include polyolefin-based nonwoven fabrics such as polypropylene and polyethylene, polyester-based nonwoven fabrics such as polyethylene terephthalate and polybutylene terephthalate, polyamide-based nonwoven fabrics such as 6-nylon and 6,6-nylon, and rayon nonwoven fabrics. One example is the use of air-through nonwoven fabrics, which are made by bonding composite fibers with hot air. For example, thermoplastic resin films such as polyethylene or other polyolefin films are used as the film.

[0054] Furthermore, depending on the type of absorbent article, a sheet-like absorbent paper 23 may be placed between the surface sheet (top sheet) 21 and the absorbent body 10, which consists of pulp fibers 11 and a superabsorbent polymer 12. For example, a polyolefin nonwoven fabric may be used as the absorbent paper 23. In addition, an outer sheet made of breathable nonwoven fabric or the like may be provided on the side of the back sheet 22 opposite to the side where the absorbent material 10 is installed. In addition, side sheets 24 to prevent leakage may be provided on both sides in the width direction of the absorbent article, and for these parts, for example, water-repellent treated nonwoven fabric (e.g., polyolefin-based nonwoven fabric, polyurethane nonwoven fabric, etc.), breathable synthetic resin film (polyolefin-based film, styrene-based elastomer film, etc.), or elastic material thread elastic 25 (spandex, urethane rubber, natural rubber, synthetic rubber, etc.) may be used. In addition, adhesive tapes (hook-and-loop fasteners) made of polyolefins such as polypropylene or synthetic rubber may be used as fastening materials, and cellulose nanofibers (CNF) with silver ions or fragrances that have deodorizing and antibacterial effects may be used as pulp fibers 11.

[0055] Thus, the absorbent material to be recycled consists of an absorbent body 10 made of pulp fibers 11 and SAP 12, and sheets 20 such as a surface sheet 21 made of film or nonwoven fabric, a back sheet 22, absorbent paper 23, and side sheets 24, and these components are joined together with hot melt adhesive. Hot melt adhesives typically contain a base polymer, a tackifier, and a plasticizer. Examples of base polymers include styrene-based resins such as styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-butadiene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-propylene-styrene block copolymer (SEPS), and styrene-butadiene copolymer (SBR); rubber-based resins such as polyisoprene and natural rubber; acrylic-based resins such as ethylene vinyl acetate copolymer; silicone-based resins such as polydimethylsiloxane polymer; and olefin-based thermoplastic resins such as polyethylene. Examples of tackifiers include rosin, terpene resins, and petroleum resins, while plasticizers include process oils and polybutene. Other materials may also be present, such as waxes like paraffin wax and polyethylene, fillers like calcium carbonate, titanium dioxide, and talc, and stabilizers like phenol and toluene.

[0056] To explain using diapers as an absorbent item as an example, as shown in Figure 1, diaper D as an absorbent item has a multilayer structure in which absorbent paper 23 is placed beneath a surface sheet (surface material) 21 made of nonwoven fabric, and an absorbent body 10 made of pulp fibers (flap pulp) 11 and granular SAP 12 wrapped in it is placed further beneath that, and a back sheet (waterproof material) 22 made of thermoplastic resin film is placed on the outside of the absorbent body 10 on the side opposite to the surface sheet 21, and an outer packaging material (surface material) made of nonwoven fabric (not shown) is placed on the outside of that as well. In addition, elastic gathers to prevent leakage are formed on both sides in the width direction by side sheets 24, and elastic threads 25 are placed there. In addition, a fastening material (not shown) is attached to the back sheet 22 side. In diaper D with this configuration, the absorbent material 10 made of pulp fibers 11 and SAP 12 is surrounded by a surface sheet 21 and a back sheet 22 made of nonwoven fabric or thermoplastic resin film, and the surface sheet 21 and the back sheet 22 are joined together via hot melt adhesive. The side sheets 24 that form the gathers and the outer sheet are also joined to the surface sheet 21 and the back sheet 22 via hot melt adhesive.

[0057] Next, a method and apparatus for recycling substandard products, chips, etc., generated during the manufacturing process of such absorbent articles will be explained with reference to Figures 2 to 6. The method and apparatus for recycling absorbent articles of this embodiment separate and recover the constituent materials from off-spec products (defective products) and scraps (cut edges) that are generated during the manufacturing of absorbent articles; in other words, it separates and recovers the constituent materials of unused absorbent articles for recycling.

[0058] As shown in Figure 2, the method for recycling unused absorbent article components according to this embodiment includes a solvent treatment step (step S1) in which off-spec absorbent article products, scraps, etc. (hereinafter simply referred to as "processed material 110") extracted, recovered, and collected during the manufacturing process of absorbent article products are immersed in a solvent 120 to dissolve hot melt adhesive (hereinafter simply abbreviated as "adhesive") in the solvent 120; a separation and recovery step (step S2) in which the components of the processed material 110 from which the adhesive has been removed by dissolving the adhesive in the solvent 120 are separated and recovered into SAP 12, a sheet 10, and pulp fibers 11; and a drying step (step S3) in which the separated and recovered components are dried.

[0059] Furthermore, as shown in Figures 3 to 6, the apparatus for recycling the constituent materials of unused absorbent articles according to this embodiment includes a solvent treatment section 510 that immerses the workpiece 110 in a solvent 120 to dissolve the adhesive in the solvent 120, a separation and recovery means consisting of a screen F, solvent 120, etc., that separates and recovers the constituent materials of the workpiece 110 from which the adhesive has been removed by dissolving the adhesive in the solvent 120 into SAP 12, a sheet 10 and pulp fibers 11, and a drying means for drying the separated and recovered constituent materials.

[0060] First, in the solvent treatment process (step S1), the materials to be treated 110, such as off-spec products and chips generated during the manufacturing process of absorbent articles, are immersed in the solvent 120 in the solvent treatment area 510. Furthermore, if off-spec products or scraps generated during the manufacturing process of absorbent materials are transported in bags or compressed packaging, the bags are opened or the packaging is removed to take out the material to be processed 110, and it is then put into the solvent processing unit 510. From the standpoint of preventing clogging of the inlet of the solvent processing unit 510, the material to be processed 110 may be folded before being put in or pre-cut to a size that fits into the inlet, but it is not finely defibrated, crushed, or pulverized, and is, for example, about 3 to 120 cm in length and 3 to 120 cm in width.

[0061] In the solvent treatment section 510, where unused absorbent articles such as off-spec products and chips generated during the manufacturing process of absorbent articles are immersed in a solvent 120, for example, a treatment tank containing the articles 110 and the solvent 120 is used. The articles 110 are placed into the treatment tank, and a predetermined amount of solvent 120 is added to a predetermined depth, immersing the articles 110 in the solvent 120. Preferably, in the treatment tank where the articles 110 are immersed in the solvent 120, physical shocks and external forces such as vibration, stirring, and centrifugal force (rotation) are usually applied to ensure that the solvent 120 penetrates the entire article 110 evenly and uniformly, and to promote the separation of the constituent members of the articles 110, particularly the separation of the sheet 20 and the absorbent 10 whose bond has been broken by the dissolution of the adhesive in the solvent 120, making separation easier.

[0062] Here, as solvent 120, for example, petroleum-based solvents containing paraffin, naphthenes, etc., chlorine-based solvents such as tetrachloroethylene, halogenated hydrocarbon solvents such as HCFC-225 and HFC-365, and silicone-based solvents such as cyclic or linear silicones can be used, but among these, petroleum-based or halogenated hydrocarbon dry cleaning solvents are preferred.

[0063] Suitable petroleum-based solvents include kerosene (mainly composed of C9-C15 hydrocarbons) and No. 5 industrial gasoline (cleaning solvent) used in dry cleaning. Petroleum-based solvents used in dry cleaning have a specific gravity of approximately 0.73-0.80 and are hydrocarbon mixtures. As halogenated hydrocarbon solvents, bromine-based solvents such as 1-bromopropane, which are used as dry cleaning solvents, chlorine-based solvents such as tetrachloroethylene (perchloroethylene) and trichloroethylene, and fluorine-based solvents such as 1,1,1,3,3-pentafluorobutane can be used. As for silicone-based solvents, decamethylcyclopentasiloxane and decamethyltetrasiloxane, which are used as dry cleaning solvents, can be used.

[0064] In the solvent treatment process (step S1), when the workpiece 110 is immersed in the solvent 120, the adhesive that was joining the constituent materials of the workpiece 110 dissolves in the solvent 120 and is removed from the workpiece 110. As a result, the joints of the constituent materials of the workpiece 110 peel off, causing dissociation and separation of the constituent materials of the workpiece 110. In other words, the workpiece 110 is decomposed as the bonds between the film, nonwoven fabric, or other sheet 20 that constitutes the absorbent article, which is the workpiece 110, are broken, and the workpiece 110 is separated into SAP 12, pulp fibers 11, sheet 20, etc. In particular, by chemically treating the workpiece 110 with the solvent 120, the nonwoven fabric or film sheet 20 peels off while generally maintaining its shape at the time of input, without being shredded. Then, the pulp fibers 11 and SAP 12 of the absorbent material 10, which were contained within the surface sheet 21 and the back sheet 22, are scattered into the solvent 120 as the bonds between the nonwoven fabric and film sheets 20 separate in the solvent 120.

[0065] Thus, in the solvent treatment step (step S1), the adhesive is removed from the workpiece 110 by immersing it in the solvent 120 and dissolving the adhesive in the solvent 120. In particular, in this chemical treatment where the adhesive is dissolved and removed by solvent 120, the material to be treated 110 is decomposed into its constituent materials. This treatment can reduce the bonding force between the sheets 20 and separate the constituent materials of the material to be treated 110 at room temperature, and since heating or crushing is not required to dismantle the material to be treated 110, it requires less energy and energy costs.

[0066] Next, in the separation and recovery step (step S2), the constituent materials of the workpiece 110 from which the adhesive has been dissolved and removed by immersion in the solvent 120 are separated and recovered. When the workpiece 110 is immersed in the solvent 120, the adhesive is dissolved and removed by the solvent 120, which breaks the bonds between the film, nonwoven fabric, or other sheet 20 of the workpiece 110. As a result, the workpiece 110 decomposes and dissociates, allowing the constituent materials of the workpiece 110 to be separated and recovered.

[0067] In this embodiment, the workpiece 110 is dismantled by dissolving the adhesive in the solvent 120 without finely crushing the workpiece 110. As a result, the nonwoven fabric or film sheet 20 is peeled and separated without being fragmented, and the pulp fibers 11 and SAP 12 of the absorbent 10, which were embedded between the surface sheet 21 and back sheet 22 made of the nonwoven fabric or film, are scattered into the solvent 120, allowing the SAP 12 to be easily separated from the sheet 20, etc.

[0068] In particular, by removing the adhesive from the workpiece 110, SAP 12 is less likely to adhere to and remain on the sheet 20 made of nonwoven fabric or film and the pulp fibers 11, and the residue of SAP 12 on the sheet 20 made of nonwoven fabric or film and the pulp fibers 11 is reduced, allowing the SAP 12 to be separated cleanly and easily from the sheet 20 made of nonwoven fabric or film and the pulp fibers 11 and dispersed into the solvent 120. Furthermore, since the sheet 20 made of nonwoven fabric or film and the pulp fibers 11 are separated while maintaining large dimensions without being fragmented, the large size difference between the sheet 20 made of nonwoven fabric or film and the pulp fibers 11 and the SAP 12 makes separation easy. Therefore, in the method and apparatus for recycling absorbent articles of this embodiment, the SAP 12 is separated from the remaining constituent materials, including the sheet 20 and pulp fibers 11, and recovered.

[0069] Here, the SAP 12 constituting the material to be processed 110 and the other sheets 20 and pulp fibers 11, etc., can be separated and recovered by utilizing their dimensional differences, specific gravity differences (density differences), sedimentation / buoyancy differences, resistance, etc. As a separation and recovery means for separating and recovering SAP12 from the sheet 20 and pulp fibers 11, for example, a screen, sieve, filter, etc. (hereinafter collectively referred to as "screen F") having multiple holes that allow SAP12 to pass through but not the sheet 20 made of nonwoven fabric or film and the pulp fibers 11 can be used. Preferably, a screen with a mesh opening in the range of 0.1 to 5 mm, more preferably in the range of 0.1 to 3 mm can be used. In this case, separation may be promoted by vibrating the screen F, and a roller screen may be used. Furthermore, the screen F may be arranged in multiple stages or cascaded. In this type of filtration separation using screen F, the nonwoven fabric or film sheet 20 is not broken down, and the original shape is largely maintained. Furthermore, the SAP 12 is not pulverized, meaning that no load is placed on the constituent materials. This allows for the separation of small granular material P such as SAP 12 from coarse fragments / fibrous material LF such as pulp fibers 11 and sheet 20.

[0070] For example, by passing the treatment solution (solid-liquid mixture) obtained by immersing the material to be treated 110 in solvent 120 through the screen F described above, granular material P such as SAP 12 and the treatment solution (solvent 120) pass through the screen F, while coarse fragments and fibrous material LF such as nonwoven fabric or film sheets 20 and pulp fibers 11 are captured and recovered on the screen F. In this way, the coarse fragments and fibrous material LF such as pulp fibers 11 and sheets 20 and granular material P such as SAP 12 can be separated and recovered separately without finely breaking down the constituent materials.

[0071] Alternatively, as shown in Figures 3 to 6, a screen F can be installed in a treatment tank in which the workpiece 110 is immersed in a solvent 120. By utilizing the gravity of the decomposed constituent materials of the workpiece 110, which settle or float in the solvent 120 due to the dissolution of the adhesive in the solvent 120, it is possible to separate them into coarse fragments / fibrous materials LF such as pulp fibers 11 and sheets 20, and granular materials P such as SAP 12, and recover them separately.

[0072] For example, as shown in Figures 3 and 4, if a solvent 120 with a specific gravity greater than that of the SAP 12 of the absorbent 10, preferably a halogenated hydrocarbon-based dry cleaning solvent or a mixture thereof with a petroleum-based solvent having a specific gravity of 1.6 or more and 1.8 or less, is used, when the adhesive bond in the workpiece 110 is broken by immersion of the workpiece 110 in the solvent 120, the SAP 12 will float in the solvent 120 in the treatment tank because its specific gravity is lower than that of the solvent 120 and it does not absorb the solvent 120.

[0073] Therefore, as shown in Figures 3 and 4, the above-mentioned screen F is installed at a predetermined position in the processing tank of the solvent processing unit 510 where the material to be processed 110 is immersed in the solvent 120, and the material to be processed 110 is supplied to a position below the screen F. As a result, granular material P such as SAP 12 floats up, passes through the screen F and moves to a position above the screen F, while coarse fragments and fibrous material LF such as pulp fibers 11 and sheets 20 remain below the screen F without passing through it. Thus, granular material P such as SAP 12 and coarse fragments and fibrous material LF such as pulp fibers 11 and sheets 20 are separated above and below the screen F.

[0074] Specifically, solvent 120, which has a higher specific gravity than SAP 12, is injected from a solvent tank T connected to the solvent processing unit 510 and containing solvent 120 into the processing tank of the solvent processing unit 510, and the material to be processed 110 is supplied below the screen F in the processing tank of the solvent processing unit 510, which is equipped with a screen F. At this time, preferably, the solvent 120 is stirred and vibrated by an agitating means that is immersed in the solvent 120, or by the rocking of the processing tank, etc. When the material to be treated 110 is immersed in the solvent 120 and stirred, the SAP 12, which is lighter in specific gravity than the solvent 120, is granular, and has small dimensions, rises (floats) in the solvent 120, passes through the screen F, and moves to the area above the screen F. Meanwhile, the pulp fibers 11 and sheets 20, which are larger in dimensions than the SAP 12 due to the entanglement of single fibers, remain below the screen F. Therefore, the granular material P such as SAP 12 and the remaining coarse fragments / fibrous material LF such as the pulp fibers 11 and sheets 20 can be recovered separately.

[0075] The granular material P, such as SAP12, that floats above screen F can be discharged outside the solvent treatment unit 510 along with the solvent 120 and separated and recovered from the solvent 120 using another screen, or it can be captured and recovered on screen F. Coarse fragments and fibrous materials LF, such as pulp fibers 11 and sheets 20 that remain below screen F, can also be discharged to the outside of the solvent treatment unit 510 together with the solvent 120 and separated and recovered from the solvent 120 using another screen, or they can be accumulated at the bottom of the treatment tank and recovered when the solvent 120 is discharged.

[0076] In this solvent treatment unit 510, the adhesive of the workpiece 110 is dissolved in the solvent 120 by immersing the workpiece 110 in the solvent 120, thereby disintegrating the workpiece 110. In the solvent 120, granular material P such as SAP 12 and coarse fragments / fibrous material LF such as pulp fibers 11 and sheets 20 are separated and recovered by filtration separation using a screen F and flotation separation and recovery means for SAP 12. This method prevents clogging caused by the accumulation of coarse fragments / fibrous material LF on the screen F, compared to simply passing (flowing) the treatment liquid in which the workpiece 110 has been disintegrated in the solvent 120 through the screen F, allowing for more efficient separation. Furthermore, it reduces physical impact on the constituent materials, meaning separation can be performed under gentle conditions, thus maintaining higher quality without degrading the SAP 12. In addition, the equipment can be made simpler, resulting in lower costs.

[0077] In other words, by separating SAP12 from the remaining pulp fibers 11 and sheet 20 by utilizing the difference in specific gravity (gravity) in solvent 120, which has a higher specific gravity than SAP12, and filtration separation by screen F, it is possible to separate and recover high-purity SAP12 from pulp fibers 11 and sheet 20 with an extremely low SAP12 content, with low energy and minimal load on SAP12. The SAP12 can be separated from the remaining pulp fibers 11 and sheet 20 with good separation accuracy, and high-purity SAP12 and pulp fibers 11 and sheet 20 with an extremely low SAP12 content can be obtained productively.

[0078] Furthermore, as shown in Figures 5 and 6, if a solvent 120 with a specific gravity lower than that of the SAP 12 of the absorbent 10 is used, preferably a petroleum-based, halogenated hydrocarbon-based, or mixture thereof dry cleaning solvent with a specific gravity of 0.7 or higher and 1.5 or lower, when the adhesive bond in the workpiece 110 is broken by immersion of the workpiece 110 in the solvent 120, the SAP 12 will settle (fall) in the solvent 120 of the treatment tank because its specific gravity is higher than that of the solvent 120 and it does not absorb the solvent 120.

[0079] Therefore, as shown in Figures 5 and 6, the screen F is installed at a predetermined position below the liquid level of the solvent 120 in the processing tank of the solvent processing unit 510 where the workpiece 110 is immersed in the solvent 120, but above the bottom. When the workpiece 110 is placed above the screen F, the solvent 120 penetrates the workpiece 110 and the adhesive bonds are broken, causing the sheet 20, pulp fibers 11, SAP 12, etc. of the workpiece 110 to scatter in the solvent 120. The granular material P such as SAP 12 passes through the screen F and settles, but the coarse pieces and fibrous material LF such as the sheet 20 and pulp fibers 11 of the nonwoven fabric or film do not pass through the screen F. Thus, the granular material P such as SAP 12 and the coarse pieces and fibrous material LF such as the sheet 20 and pulp fibers 11 are separated above and below the screen F. This allows the constituent materials to be separated into granular material P such as SAP12 and coarse fragments / fibrous material LF such as sheet 20 and pulp fibers 11 without finely breaking them apart, and to be recovered separately. Preferably, by stirring at least the area above screen F or vibrating screen F, the constituent materials of the material to be processed 110 become easier to dissociate and separate, and clogging due to accumulation of sheet 20 on screen F can be prevented, allowing for efficient separation of granular material P such as SAP12 and coarse fragments / fibrous material LF such as sheet 20 and pulp fibers 11.

[0080] Specifically, the material to be treated 110 is introduced into the treatment tank of the solvent treatment unit 510 equipped with a screen F from above the screen F, and a solvent 120 having a specific gravity lower than the specific gravity of SAP 12 of the absorbent body 10 is poured from the solvent tank T connected to the solvent treatment unit 510 so that the liquid level is above the screen F, thereby immersing the material to be treated 110 in the solvent 120. At this time, preferably, the solvent 120 is stirred and vibrated by a stirring means that immerses the material in the solvent 120, or by the rocking of the treatment tank, etc. When the object to be treated 110 is immersed in the solvent 120, the adhesive in the object to be treated 110 dissolves in the solvent 120, and as the adhesive is dissolved and removed from the object to be treated 110, the object to be treated 110 decomposes in the solvent 120, and its constituent materials become scattered. Furthermore, among the constituent materials of the material to be processed 110, granular materials P such as SAP 12, which have a specific gravity greater than the solvent 120 and are smaller in size than the sheets 20 and pulp fibers 11, pass through the screen F and settle, while coarse pieces and fibrous materials LF such as the sheets 20 and pulp fibers 11, which are larger in size than SAP 12, remain above the screen F. From this point, the coarse fragments and fibrous material LF, such as the sheet 20 and pulp fibers 11, and the granular material P, such as SAP 12, can be recovered separately.

[0081] Furthermore, the coarse fragments and fibrous materials LF, such as the sheet 20 and pulp fibers 11, that remain above the screen F can be recovered by, for example, scraping, scooping up, or winding them up from the solvent 120 using a sheet recovery means to discharge them outside the solvent treatment unit 510; they can be captured and recovered on the screen F; or they can be discharged from the solvent treatment unit 510 together with the solvent 120 and separated from the solvent 120 using another screen or the like to recover them. Furthermore, granular material P such as SAP12 that settles below screen F can also be discharged to the outside of the solvent treatment unit 510 together with the solvent 120 and separated and recovered from the solvent 120 using another screen, or it can be collected by accumulating it at the bottom of the treatment tank when the solvent 120 is discharged.

[0082] In this method, where the workpiece 110 is immersed in a solvent 120 in a solvent treatment unit 510, and the constituent materials of the workpiece 110 are separated and recovered by sedimentation in the solvent 120 and separation and recovery by a screen F, coarse fragments / fibrous materials LF such as sheets 20 and pulp fibers 11 and granular materials P such as SAP 12 are separated and recovered. This method prevents clogging caused by the accumulation of sheets 20 etc. on the screen F, compared to the case where the treatment liquid obtained by immersing the workpiece 110 in the solvent 120 is passed through (flowed) through the screen F, allowing for more efficient separation. Furthermore, it reduces physical impact on the constituent materials, meaning that separation can be performed under gentle conditions, thus maintaining higher quality without degrading the SAP 12. In addition, the equipment can be made simpler in configuration, resulting in lower costs.

[0083] In this method, the material to be treated 110 is immersed in the solvent 120 in the solvent treatment unit 510. The gravitational force (difference in specific gravity) of the settling or floating of the constituent materials of the material to be treated 110 in the solvent 120, along with filtration separation by the screen F, separates and recovers coarse fragments / fibrous materials LF such as the sheet 20 and pulp fibers 11 from granular materials P such as SAP 12. This method allows for high-precision separation of SAP 12 from the remaining pulp fibers 11 and sheet 20 with minimal energy load, without causing the SAP 12 to become finely granulated or pulverized. The separated and recovered SAP 12 is free of adhesive residue and exhibits minimal degradation, resulting in a high-quality material suitable for material recycling. In particular, even when the material to be treated 110 is immersed in the solvent 120, the SAP 12 does not absorb oil and, as described above, can be separated and recovered without being finely granulated or pulverized. This allows for high recovery rates while maintaining the original properties such as water absorption, without significantly altering the particle size distribution. Therefore, the recovered SAP12 is of high quality and suitable for material recycling as an absorbent material 10 for absorbent articles. Furthermore, because the SAP12 is not granulated or pulverized, the remaining pulp fibers 11 and sheets 20, etc., after the SAP12 has been separated, have very little SAP12 contamination and are free of adhesive, resulting in high quality. Consequently, the solid fuel 30 obtained by solidifying these materials is also of high quality, with low moisture, salt, and ash content and high calorific value, due to the absence of SAP12 and adhesive contamination. In addition, the solid fuel 30 obtained by solidifying the pulp fibers 11 and sheets 20, etc., separated from the SAP12, is lightweight because it does not expand due to the absorption of moisture and water by the SAP12, and requires less space and energy for storage and transportation, as well as reducing the burden on workers during transportation.

[0084] In addition, when implementing the present invention, a rotatable drum (drum screen) with a screen F on its outer circumference is installed in the processing tank as a solvent processing unit 510, and the material to be processed 110 is immersed in the solvent 120 inside the drum to perform solvent processing. By rotating the drum at this time, the agitation, physical impact such as centrifugal force, and external forces promote the penetration of the solvent 120 into the material to be processed 110 and the dissolution of the adhesive into the solvent 120, and the dissolution of the adhesive into the solvent 120 makes it easier for the constituent materials to dissociate and separate. Then, due to the centrifugal force of rotation, granular material P such as SAP 12 is discharged from the holes of the screen F around the drum to the outer casing outside the rotating drum, and coarse pieces / fibrous material LF such as nonwoven fabric or film sheets 20 and pulp fibers 11 remain inside, so that the coarse pieces / fibrous material LF such as sheets 20 and pulp fibers 11 and the granular material P such as SAP 12 can be separated and recovered separately without finely breaking the constituent materials. Furthermore, for example, it is possible to separate the SAP 12 by applying a liquid flow to the solvent 120 in which the material to be processed 110 is immersed, thereby moving the SAP 12 to a location separate from the pulp fibers 11 and sheets 20, or to separate and recover it using a wet classifier such as a liquid cyclone HC that utilizes centrifugal force.

[0085] Furthermore, the granular material P containing SAP12, etc., may be subjected to the drying process (step S3) described later after separating and removing foreign matter such as rubber thread 25 and other constituent materials such as tape, or these foreign matter may be separated and removed after the drying process (step S3). The separated rubber thread 25 and other constituent materials such as tape can be mixed with the sheet 20 and coarse pieces / fibrous material LF such as pulp fibers 11 to produce solid fuel, but it is also possible to recycle them as material.

[0086] In particular, in this embodiment, since the material to be processed 110 is not finely crushed, the recovered SAP 12 contains little contamination from fine sheets 20, rubber threads 25, tapes, etc., making foreign matter separation easy and allowing SAP 12 to be separated and recovered with high purity. Since SAP 12 and other materials are not granulated or pulverized and do not flow out, there is no burden on the wastewater. Furthermore, since the adhesive of the material to be processed 110 is dissolved in the solvent 120, the material to be processed 110 is decomposed and dismantled, and its constituent materials are separated and recovered. As a result, the nonwoven fabric or film sheet 20 is not shredded but is dissociated while generally maintaining its shape at the time of input. Moreover, since the adhesive is removed from the material to be processed 110, SAP 12 is less likely to adhere to and remain on the nonwoven fabric or film sheet 20 and pulp fibers 11. Therefore, the nonwoven fabric or film sheet 20 and pulp fibers 11, etc., become high-quality materials with an extremely low SAP 12 content.

[0087] Thus, in this embodiment, the material to be processed 110 is dismantled by removing the adhesive from the material to be processed 110 without finely defibrating, crushing, or pulverizing it. Therefore, it is easy to separate the SAP 12 from the sheets 20, such as the surface sheet 21 and back sheet 22 made of nonwoven fabric or film, and the pulp fibers 11. Consequently, they can be separated accurately with little energy, i.e., under low-load conditions, without having to input excessive energy that would cause the SAP 12 to become finely granulated or pulverized. Furthermore, since the SAP 12 can be separated without causing deterioration due to fine granulation or pulverization, or changes in properties such as water absorption, it is suitable for recycling as an absorbent material 10 for absorbent articles. In other words, by immersing the workpiece 110 in solvent 120 to dissolve the adhesive and thus dismantling the workpiece 110, the adhesive of the workpiece 110 is removed, causing the sheet 20 to separate while maintaining its large dimensions without being fragmented. This eliminates the entanglement and adhesion of the constituent materials of the workpiece 110 that would occur if it were finely defibrated, crushed, or pulverized, and the constituent materials of the workpiece 110 can be easily scattered. As a result, SAP 12 can be separated and recovered with less energy, and the recovery rate of SAP 12 is also high.

[0088] Thus, in the separation and recovery step (step S2), at least the SAP 12, the sheet 20 such as nonwoven fabric or film, and the pulp fibers 11 are separately separated and recovered from the constituent materials of the treated material 110 from which the adhesive has been removed using a separation and recovery means such as a screen F.

[0089] Next, in the drying process (step S3), in the drying section 550 equipped with drying means, each of the separated and recovered constituent materials is dried by the drying means, thereby removing and desolventing any solvent 120 remaining in each of the separated and recovered constituent materials. As for drying methods, for example, the solvent 120 can be volatilized by natural drying at room temperature, drying at a temperature higher than room temperature, air drying with ambient air, drying by blowing hot air, or reduced pressure drying, and heaters, vacuum pumps, fans, etc., can be used. However, in the case of petroleum-based solvent 120, since it has a low flash point, the solvent 120 is evaporated under reduced pressure, with nitrogen purging and control of gas and oxygen concentrations. It is preferable to dry the solvent until the solvent content is 1% by mass or less. During this drying process, the separated and recovered SAP 12, the sheet 20 such as nonwoven fabric or film, and the pulp fibers 11 may be dried individually or together. Since the drying is performed using solvent 120, it can be done with low load and energy saving. In the drying section 550, the drying time can be shortened by preventing uneven drying and promoting solvent removal through a mechanism that rotates the processing tank, such as a mechanism that rotates the tank itself or a mechanism that rotates a rotating body installed inside the tank, or by using airflow.

[0090] SAP12 is collected separately, and after the granular material P containing the dried SAP12 is separated and removed from the elastic thread 25, tape, and other constituent materials, it is recovered as a recyclable product. In other words, SAP12 that can be recycled is recovered by separating and removing the elastic thread 25, tape, and other constituent materials from the granular material P containing the collected and dried SAP12. The separated rubber threads 25 and other constituent materials such as tape can be mixed with the sheets 20 and coarse fragments / fibrous materials LF such as pulp fibers 11 to produce solid fuel, but they can also be recycled as material resources.

[0091] The recovered SAP12 can be reused in absorbent materials, and can also be used in a wide range of applications, including agriculture and horticulture (soil water retention agent, pesticide disintegration aid, etc.), food (freshness preservative, antifreeze, coolant), civil engineering and construction (solidifying agent, anti-condensation agent, waterproofing agent), cosmetics and pharmaceuticals (fragrances, cosmetics, patches), hygiene products, emergency toilets, electrical and electronic materials (waterproofing agent for optical cables), and paints.

[0092] Furthermore, in this embodiment, the remaining sheet 20 and coarse fragments / fibrous material LP such as pulp fibers, after the SAP 12 has been separated and recovered from the material to be processed 110, are solidified in the solid fuel process (step S5) by molding, cooling, etc., and are thermally recycled as solid fuel 30 (Refuse derived paper and plastics densified fuel: RPF). In particular, the remaining sheets 20 and coarse fragments / fibrous materials LP, such as pulp fibers, from which SAP 12 has been separated from the unused absorbent material 110, have had the adhesive removed and contain fewer impurities such as moisture, ash, and chlorine. As a result, they have good ignition properties, a high calorific value, and become a stable, high-quality solid fuel 30. That is, a high calorific value comparable to coal and coke can be obtained, and the solid fuel 30 is of good quality that is less likely to cause boiler corrosion due to chlorine gas or the generation of dioxins.

[0093] In other words, the material to be treated 110, which is an unused absorbent article, is dismantled by immersing it in solvent 120 to dissolve the adhesive, and the sheet 20 and coarse pieces / fibrous material LP such as pulp fibers, separated from SAP 12 by filtration separation using a screen F, have an extremely low amount of SAP 12 contamination because the SAP 12 has not been finely ground or pulverized, and furthermore, there is no adhesive adhesion, resulting in a high-quality product. Therefore, the solidified fuel 30 obtained by forming these materials with a molding machine and then cooling them with a cooling machine results in a solid fuel with a low moisture content due to the extremely low SAP 12 content. Furthermore, since SAP 12 is not inactivated with an inactivating agent such as calcium chloride, and the adhesive has been removed, the content of impurities such as ash and chlorine is also low. Therefore, it has a high calorific value and is of high quality. Furthermore, in the solid fuel 30 obtained by solidifying the pulp fibers 11 and sheets 20, etc., from which SAP12 has been separated, expansion due to water absorption by SAP12 does not occur, resulting in a compact and lightweight product. This allows for space-saving and energy-efficient storage and transportation, and reduces the burden on workers during transportation, enabling safer work. Moreover, because the proportion of SAP12 is extremely low, there is no risk of off-odors due to the heat accumulation of SAP12, nor is there any risk of ignition.

[0094] Thus, in this embodiment, in the solvent treatment section 510, a solvent treatment step (step S1) is performed in which the workpiece 110, which is an unused absorbent article formed by surrounding an absorbent body 10 containing pulp fibers 11 and SAP 12 with a sheet 20 such as a film or nonwoven fabric and joining the opposing sheets 20 with an adhesive, is immersed in a solvent 120 to dissolve the adhesive of the workpiece 110 in the solvent 120. In the separation and recovery step (step S2), the constituent materials of the workpiece 110 from which the adhesive has been dissolved and removed are separated and recovered by a separation and recovery means into at least the sheet 20 and pulp fibers 11 and SAP 12. In the drying step (step S3), the separated and recovered sheet 20 and pulp fibers 11 and SAP 12 are dried by a drying means. In this way, at least SAP 12 and the sheet 20 such as a nonwoven fabric or film and pulp fibers 11 are separated and recovered from the workpiece 110, which is an unused absorbent article.

[0095] Thus, in this embodiment, the material to be processed 110 is disassembled and broken down by dissolving the adhesive in the solvent 120 without finely crushing the material to be processed 110, thereby separating and recovering the constituent materials. As a result, the nonwoven fabric or film sheet 20 is separated while largely maintaining its original shape without being fragmented (decomposed), and the adhesive is removed from the material to be processed 110. This makes it difficult for the absorbent 10 of SAP 12 to adhere to and remain on the nonwoven fabric or film sheet 20 and pulp fibers 11, making it easy to separate the nonwoven fabric or film sheet 20 and pulp fibers 11 from the SAP 12. Therefore, SAP 12 can be separated from the sheet 20 and pulp fibers 11 efficiently and accurately with less energy and energy cost, and the recovery rate is also high. Furthermore, since the separation of the sheet 20 and pulp fibers 11 from the SAP 12 is easy without applying excessive energy, separation can be performed with less load, and the miniaturization and degradation of SAP 12 are suppressed. Furthermore, the separated SAP12 has had the adhesive removed. As a result, the recovered SAP12 is of high quality, suitable for material recycling, and has properties that are not inferior to those of virgin raw materials. Therefore, it can be reused as an absorbent material 10 in absorbent articles, enabling material recycling for a wide range of applications.

[0096] Furthermore, since the SAP 12 is separated from the remaining sheet 20 and pulp fibers 11, the solid fuel 30 obtained by solidifying them has a low moisture content, and because the adhesive is also removed, it contains less impurities such as ash and chlorine. Therefore, it becomes a high-quality solid fuel 30 with a high calorific value. In particular, in this embodiment, the material to be treated 110 is immersed in solvent 120 to remove the adhesive, and the sheet 20 and pulp fibers 11 and SAP 12 are separated and recovered in a wet state, so separation can be performed accurately with low energy load, and the SAP 12 is not easily pulverized or atomized, so a high-quality solid fuel 30 with an extremely low proportion of SAP 12 and adhesive is obtained, making it highly valuable as a fuel. Furthermore, with solid fuel 30 obtained by solidifying the remaining sheet 20 and pulp fibers 1 after separating SAP 12 from the absorbent material, the SAP 12 does not absorb moisture or expand due to water absorption, resulting in a compact and lightweight product that requires less space and energy for storage and transportation, and reduces the burden on workers during transportation, allowing for safer work. In addition, there is no risk of odor generation or ignition due to heat accumulation of SAP 12.

[0097] Furthermore, this embodiment includes an adhesive separation and recovery step (step S4) in which the solvent 120 in which the adhesive is dissolved after the constituent materials of the workpiece 110 have been recovered is distilled, and the adhesive precipitated by distillation is separated and recovered. In the adhesive separation and recovery step (step S4), the adhesive is precipitated and separated from the solvent 120 in which the adhesive remains after the constituent materials of the workpiece 110 have been recovered by distillation, which is the adhesive separation and recovery means. Furthermore, in the separation and recovery apparatus of this embodiment, a solvent circulation path 540 is formed connecting the solvent tank T and the distillation section 530. The solvent 120 from which the adhesive has been removed by cooling the solvent gas in the distillation section 530 is supplied to the solvent tank T through the solvent circulation path 540 and reused as the solvent 120 for immersion treatment of the workpiece 110. The solvent circulation path 540 is equipped with a filtration section with a filter, and after foreign matter is removed from the solvent 120 from which the adhesive has been removed by the filter in the filtration section, it is reused again as the solvent 120 for immersion treatment of the workpiece 110.

[0098] In other words, the solid adhesive can be separated and recovered from the solvent 120 by distilling the solvent 120 in which the adhesive is dissolved and precipitating the adhesive. The evaporated solvent gas then condenses upon cooling, becoming liquid solvent 120 from which the adhesive has been removed. This liquid solvent is then filtered through the filtration section and reused as the solvent 120 into which the workpiece 110 is immersed. In particular, petroleum-based and halogenated hydrocarbon-based dry cleaning solvents 120 offer a high recovery rate for leached adhesives.

[0099] Thus, in this embodiment, the solvent 120 in which the adhesive is dissolved is not discarded externally, but the adhesive is recovered by distillation and used repeatedly as the solvent 120 for immersion treatment of the workpiece 110. Therefore, the cost can be reduced without the need for waste liquid treatment of the solvent 120. Furthermore, since the adhesive can be separated and recovered by distillation of the solvent 120 in which the adhesive is dissolved, the adhesive can also be recycled as a material, making more effective use of the resources of the constituent materials of the absorbent article. In other words, in this embodiment, the object to be treated 110 is decomposed and dismantled by dissolving the adhesive in the object to be treated 110 in the solvent 120. Since the adhesive is dissolved in the solvent 120, it is possible to precipitate the adhesive from the solvent 120 by distillation, and thus it is possible to separate and recover the adhesive from the object to be treated 110, which is an unused absorbent article, and recycle the material. Therefore, it is possible to increase the reusability and recycling rate of the constituent materials of unused absorbent articles, and contribute to environmental protection.

[0100] Furthermore, the series of recycling devices have an intake section for drawing in outside air and an exhaust section for expelling internal air. Outside air drawn in by the intake section is supplied by the operation of a fan, and internal air is appropriately treated and discharged to the outside from the exhaust section.

[0101] As described above, the method for recycling absorbent articles of this embodiment is a method for recycling the constituent materials of unused absorbent articles, such as off-spec products or scraps, which are made by surrounding an absorbent body 10 of pulp fibers 12 and superabsorbent polymer (SAP) 12 with a sheet 20 and joining the opposing sheets 20 with a hot melt adhesive. The method involves a solvent treatment step (step S1) in which the object to be treated 110, which is an unused absorbent article such as an off-spec product or scrap, is immersed in a solvent 120 to dissolve the adhesive joining the sheets 20. In a separation and recovery step (step S2), the absorbent article that has been dissociated by the dissolution of the adhesive in the solvent 120 is separated and recovered into the sheet 20 and pulp fibers 11 and the SAP 12. In a drying step (step S3), the separated and recovered sheet 20 and pulp fibers 11 and the SAP 12 are dried to volatilize the solvent 120.

[0102] Furthermore, the absorbent article recycling device of this embodiment is a device for recycling the constituent materials of unused absorbent articles, such as off-spec products or scraps, which are made by surrounding an absorbent body 10 of pulp fibers 12 and superabsorbent polymer (SAP) 12 with a sheet 20 and joining the opposing sheets 20 with a hot melt adhesive. The device comprises a solvent treatment unit 510 that immerses the workpiece 110, which is an unused absorbent article such as off-spec products or scraps, in a solvent 120 to dissolve the adhesive joining the sheets 20; a separation and recovery means such as a screen F that separates and recovers the absorbent article dissociated by the dissolution of the adhesive in the solvent 120 into the sheet 20, pulp fibers 11, and SAP 12; and a drying means such as a heater, a vacuum pump, and a fan that dries the separated and recovered constituent materials to volatilize the solvent 120.

[0103] According to this embodiment of the method and apparatus for recycling absorbent articles, the hot-melt adhesive joining the components of an unused absorbent article is dissolved in solvent 120 to dissociate the components, and the components are separated and recovered into a sheet 20, pulp fibers 11, and SAP 12. As the adhesive is dissolved and removed, the dissociation and decomposition of the absorbent article (processed material 110) becomes easier, and the recovery rate of SAP 12 can be improved. In particular, by removing the adhesive, there is no entanglement caused by the adhesive, and the sheet 20, pulp fibers 11, and SAP 12 can be easily separated from each other based on differences in size, specific gravity, etc., with less energy without fine pulverizing or pulverizing the pulp fibers 11 and SAP 12 of the absorbent material 10. Furthermore, because the adhesive is removed, SAP 12 can be separated and recovered with high quality, making it suitable for material recycling. Furthermore, because the SAP12 is not granulated or pulverized, and the adhesive is removed, the sheet 20 and pulp fibers 11 can be separated and recovered with extremely low proportions of SAP12 and adhesive, resulting in high-quality separation and recovery.

[0104] In particular, in this embodiment, the absorbent article from which the adhesive has been removed is immersed in solvent 120, and the sheet 20 and pulp fibers 11 and SAP 12 are separated and recovered in the solvent 120, and then dried. Separating the constituent materials in a wet state using the difference in specific gravity with the solvent 120 and gravity allows for separation under low-impact conditions for the constituent materials. Therefore, by separating the constituent materials under gentle conditions that do not degrade or pulverize them, the constituent materials can be separated and recovered with high quality.

[0105] Furthermore, in this embodiment, as an adhesive separation and recovery step (step S4), the adhesive is precipitated and separated and recovered by distilling the solvent 120 in which the adhesive has dissolved in the distillation section 530, thereby enabling material recycling of the adhesive as well and making more effective use of resources. In addition, since the solvent 120 distilled by the solvent circulation path 540 is reused as the solvent 120 to be immersed in the absorbent material to be treated 110 in the solvent treatment section 510, the wastewater treatment of the solvent 120 is unnecessary, making it possible to reduce the environmental burden and lower costs.

[0106] Here, an example 1 of the recycling method and recycling apparatus for unused absorbent articles in this embodiment will be described with reference to Figures 3 and 4. The recycling apparatus according to this embodiment 1 is equipped with a screen F as a separation and recovery means in the processing tank of the solvent processing unit 510 in which the material to be processed 110 is immersed in the solvent 120. The screen F has multiple holes such as round holes or slits of a diameter that allows the SAP 12 to pass through but does not allow the sheet 20 and pulp fibers 11 to pass through, and the mesh opening is about 1 mm.

[0107] In this embodiment 1, the solvent processing unit 510 consists of a separation unit 520a on which a screen F is installed, and an input unit 520b which has an opening A that opens upward into which the material to be processed 110 is introduced, is connected to the separation unit 520a below the screen F installed in the separation unit 520a, and supplies the material to be processed 110 below the screen F. In the separation section 520a where the screen F is installed, an upper discharge section B is provided above the screen F for discharging the SAP 12 that has floated to the surface of the solvent 120 to the outside by overflow, and a lower discharge section C that can be opened and closed is provided below the screen F for discharging the pulp fibers 11 and the sheet 20. Furthermore, above the screen F and below the upper discharge section B, there is an upward-opening inlet section D into which the solvent 120 is injected in order to discharge the remaining pulp fibers 11 and the sheet 20, etc., from the lower discharge section C.

[0108] As shown in Figure 3, a solvent tank T containing solvent 120 is connected to the solvent processing unit 510 via a pump and valves. When the valve is open, the pump drives the solvent 120 from the solvent tank T into the processing tank of the solvent processing unit 510. When the pump is stopped or the valve is closed, the supply of solvent 120 from the solvent tank T into the processing tank is stopped. Thus, the solvent 120 is pumped from the solvent tank T and introduced into the processing tank through opening A and inlet D of the solvent processing unit 510. When the solvent is injected into opening A, at least the lower discharge section C is closed.

[0109] As shown in Figure 4, in this embodiment 1, first, the material to be treated 110 is introduced into the opening A of the processing tank of the solvent processing unit 510. Subsequently, by opening a valve located between the connection between the solvent processing unit 510 and the solvent tank T, and operating the pump, the solvent 120 in the solvent tank T is introduced into the solvent processing unit 510 through the opening A, filling the processing tank of the solvent processing unit 510 to a predetermined position below the screen F, and immersing the material to be treated 110 in the solvent 120 within the processing tank of the solvent processing unit 510. That is, in this embodiment 1, due to the configuration of the separation unit 520a and the input unit 520b of the solvent processing unit 510 described above, the material to be treated 110 introduced through the opening A of the solvent processing unit 510 is sent below the screen F installed in the separation unit 520a and immersed in the solvent 120 below the screen F. Preferably, the solvent 120 in which the workpiece 110 is immersed is stirred using a stirring means such as a stirrer. Alternatively, the treatment tank itself is oscillated to vibrate the solvent 120. This disperses the workpiece 110, promoting the separation of constituent materials and improving treatment efficiency. In addition, to prevent the liquid level of the solvent 120 or splashing from reaching the screen F due to the stirring and vibration at this time, the liquid level of the solvent 120 injected into the treatment tank is kept at a sufficient distance from the screen F.

[0110] In this embodiment 1, a halogenated hydrocarbon-based dry cleaning solvent 120 is used as the solvent 120, having a specific gravity higher than that of the SAP 12 of the absorbent 10, and having a specific gravity of 1.5 or more and 1.8 or less. Preferably, it is tetrachloroethylene.

[0111] Next, in the treatment tank of the solvent treatment unit 510, the material to be treated 110 is immersed in the solvent 120, and when the solvent 120 is stirred, the material to be treated 110 is dispersed in the solvent 120 and becomes suspended. When the stirring is stopped after the material to be treated 110 has dispersed in the solvent 120, the granular SAP 12 floats to the surface of the liquid because the specific gravity of SAP 12 is lower than that of the solvent 120, and SAP 12 is smaller than the dimensions of the pulp fibers 11 and the sheet 20, and does not absorb the solvent 120.

[0112] Next, when the SAP 12 floats to the surface, solvent 120 is added from the opening A of the input section 520b of the solvent processing unit 510, raising the liquid level of solvent 120 in the separation unit 520a. As a result, the granular SAP 12 passes through the screen F, while the sheet 20 and cotton-like pulp fibers 11 do not pass through the screen F and remain below the screen F. Furthermore, when the liquid level of solvent 120 in the separation unit 520a is raised to the position of the upper discharge section B by injecting solvent 120, the solvent 120 on which the SAP 12 that has passed through the screen F floats overflows from the upper discharge section B and is discharged to the outside. In other words, by injecting the solvent 120, the SAP 12 that has passed through the screen F is overflowed from the upper discharge section B together with the solvent 120, thereby discharging particulate matter P such as SAP 12 together with the solvent 120 from the external discharge section B. Next, after the particulate matter P such as SAP12 is discharged from the upper discharge section B together with the solvent 120, the lower discharge section C and the inlet section D are opened, and the solvent 120 is injected from the opening of the inlet section D of the solvent processing unit 510, thereby introducing the solvent 120 from above the screen F, and the remaining pulp fibers 11 and coarse pieces / fibrous material LF such as the sheet 20 are discharged together with the solvent 120 from the opened lower discharge section C.

[0113] Thus, in this embodiment 1, a screen F is installed in the solvent treatment section 510, solvent 120 is placed in the treatment tank, and the material to be treated 110 is placed below the position of the screen F. By immersing the material to be treated 110 in a halogenated hydrocarbon dry cleaning solvent 120 such as tetrachloroethylene with a specific gravity of 1.5 or more and 1.8 or less, the SAP 12 floats to the surface above the screen F due to gravity caused by the difference in specific gravity between the solvent 120 and the SAP 12, and because the SAP 12 is smaller in size than the pores of the screen F, the pulp fibers 11 and sheet 20 remain below the screen F. As a result, the granular material P such as SAP 12 that floats to the surface above the screen F is separated from the coarse fragments / fibrous material LF such as pulp fibers 11 and sheet 20 that remain below the screen F. Therefore, the granular material P such as SAP 12 and the coarse fragments / fibrous material LF such as pulp fibers 11 and sheet 20 can be recovered separately. In other words, by separating the particulate matter P, such as SAP12, that passes through the screen F and floats to the liquid surface above the screen F, from the coarse fragments / fibrous material LF, such as pulp fibers 11 and sheets 20, that remain below the screen F, the particulate matter P, such as SAP12, is discharged from the upper discharge section B, and the coarse fragments / fibrous material LF, such as pulp fibers 11 and sheets 20, is discharged from the lower discharge section C, thereby allowing the particulate matter P, such as SAP12, and the coarse fragments / fibrous material LF, such as pulp fibers 11 and sheets 20, to be recovered separately.

[0114] The solvent 120 containing particulate matter P such as SAP 12, discharged from the upper discharge section B of the separation section 520a by overflow, is sent to the filtration section 562, where it is separated into solvent 120 and particulate matter P such as SAP 12. The particulate matter P such as SAP 12, separated from the solvent 120, is then sent to the drying section 550, where it is desolvented by vacuum drying, hot air drying, etc. Furthermore, since the dried particulate matter P such as SAP 12 may contain other constituent materials such as elastic thread 25, it is preferable to remove these other constituent materials using a screen or the like. This allows for the recovery of high-quality SAP 12.

[0115] The solvent 120 containing coarse fragments and fibrous material LF such as pulp fibers 11 and sheets 20, discharged from the lower discharge section C of the separation section 520a, is sent separately from particulate matter P such as SAP 12 to the filtration section 561, where it is separated into the solvent 120 and the coarse fragments and fibrous material LF such as pulp fibers 11 and sheets 20. The coarse fragments and fibrous material LF separated from the solvent 120 are then sent to the drying section 550, where they are desolvented by vacuum drying, hot air drying, etc.

[0116] Note that in Figures 3 and 5, multiple drying sections 550 are shown for clarity of explanation, but this does not mean that the recycling device has multiple drying sections 550; one or more drying sections 550 are sufficient. Furthermore, when implementing the present invention, filtration sections 561 and 562 may be provided in the solvent treatment section 510. The filtration means in the filtration sections 561 and 562 may be, for example, filter filtration or sedimentation separation.

[0117] Furthermore, in this embodiment 1, the dried pulp fibers 11 and coarse pieces / fibrous material LF such as the sheet 20 are compressed and molded in the solid fuel unit 580 using molding means such as a molding machine, and then cooled by cooling means such as water cooling to be converted into solid fuel. From this, a solid fuel 30 is obtained consisting of the sheet 20 and pulp fibers 11, etc., from which the SAP 12 and adhesive have been removed from the unused water-absorbing article. This solid fuel 30 is of high quality, with low moisture, salt, ash content and high calorific value because the SAP 12 and adhesive have been removed from the constituent materials of the water-absorbing article. Furthermore, other constituent materials such as the rubber thread 25, rayon, synthetic fibers, and other short fibers separated from SAP12 may also be mixed with the separately separated and recovered pulp fibers 11 and coarse fragments / fibrous materials LF such as sheets 20 in the solid fuel conversion unit 580 and converted into solid fuel.

[0118] In this embodiment 1, the filtration sections 561 and 562 are connected to the distillation section 530, and the solvent 120 discharged from the filtration sections 561 and 562 is supplied to the distillation section 530 where it is distilled. The solvent 120 discharged from the filtration sections 561 and 562 may be recovered once in a solvent recovery tank located between the filtration sections 561 and 562 and the distillation section 530, and then supplied to the distillation section 530. The solvent gas exhaust from drying in the drying section 550, such as by vacuum drying or hot air drying, may also be cooled and supplied to the solvent recovery tank and distillation section 530. Since the adhesive contained in the object to be treated 110 is dissolved in the solvent 120 into which the object to be treated 110 was immersed, the adhesive precipitates when the solvent 120 is distilled in the distillation section 530 after the object to be treated 110 has been immersed, and the adhesive is then separated and recovered.

[0119] Furthermore, in this embodiment 1, the distillation section 530 is connected to the solvent tank T by a solvent circulation path 540, and a filtration section equipped with a fine-mesh filter for removing foreign matter is provided in the middle of the solvent circulation path 540. From here, the solvent gas evaporated in the distillation section 530 is cooled and condensed to produce a liquid solvent 120. After being filtered to remove fine foreign matter by the filter in the filtration section, the solvent is sent to the solvent tank T and reused as solvent 120 for immersion treatment of the workpiece 110.

[0120] Thus, in this embodiment 1, the SAP12 is separated from the other constituent materials such as the sheet 20 and pulp fibers 11 by utilizing the buoyancy of the SAP12 in the solvent 120, which has a higher specific gravity than the SAP12, and the screen F. This allows for high-precision and efficient separation of the SAP12 from the other constituent materials such as the sheet 20 and pulp fibers 11 under extremely low-impact, gentle conditions, without expending energy to pulverize, refine, or degrade the SAP12. Therefore, SAP12 can be recovered with extremely high quality.

[0121] Furthermore, the solidified fuel 30, which is made from the remaining sheet 20 and pulp fibers 11 from which the SAP 12 has been separated, has a low moisture content and contains fewer impurities such as ash and chlorine because the SAP 12 and adhesive have been removed, resulting in a high calorific value and high quality. In Example 1, by utilizing the flotation of SAP12 in solvent 120, which has a higher specific gravity than SAP12, and the screen F, SAP12, sheet 20, and pulp fibers 11 can be discharged from the solvent treatment unit 510 in an energy-saving manner, and separation and recovery can be achieved with high separation accuracy and efficiency.

[0122] Next, another embodiment of the recycling method and recycling apparatus for unused absorbent articles in this embodiment will be described with reference to Figures 5 and 6.

[0123] This embodiment 2 differs from embodiment 1 in that a solvent 120 with a lower specific gravity than SAP 12 is used as the solvent 120 in which the workpiece 110 is immersed and the adhesive is dissolved. However, the other basic configurations are the same as in embodiment 1, so we will omit the explanation of the parts that are common with embodiment 1 and only explain the differences from embodiment 1. The recycling apparatus according to Example 2 also includes a screen F as a separation means in the processing tank of the solvent processing unit 510, which immerses the material to be processed 110 in the solvent 120. In Example 2 as well, the screen F has multiple holes such as round holes or slits of a diameter that allows the SAP 12 to pass through but does not allow the sheet 20 and pulp fibers 11 to pass through, with a mesh opening of about 1 mm.

[0124] In Example 2, first, the object to be treated 110 is placed in the treatment tank of the solvent treatment unit 510, a valve installed between the connection between the solvent treatment unit 510 and the solvent tank T is opened, and the pump is operated to introduce the solvent 120 in the solvent tank T into the treatment tank of the solvent treatment unit 510 to a predetermined liquid level above the screen F, thereby immersing the object to be treated 110 in the solvent 120 within the treatment tank of the solvent treatment unit 510. As shown in Figure 6, when the object to be treated 110 is immersed in the solvent 120 in the processing tank of the solvent processing unit 510, the adhesive in the object to be treated 110 dissolves in the solvent 120, causing the object to decompose, dissociate, and break down, and the constituent materials of the object to be treated 110 to disperse into the solvent 120. At this time, preferably, the solvent 120 in which the object to be treated 110 is immersed is stirred with a stirring means such as a stirrer. Alternatively, the processing tank itself is oscillated to vibrate the solvent 120. This promotes the decomposition of the object to be treated 110 and the separation of its constituent materials, thereby improving processing efficiency.

[0125] In this embodiment 2, a petroleum-based dry cleaning solvent 120 with a specific gravity of 0.6 or higher and 0.8 or lower, which is lower than that of SAP 12, was used as the solvent 120. Then, in the processing tank of the solvent processing unit 510, the workpiece 110 was placed above the screen F installed in the processing tank of the solvent processing unit 510. As shown in Figure 6, in the processing tank of the solvent processing unit 510, the adhesive in the workpiece 110 dissolves in the solvent 120, causing the workpiece 110 to decompose, dissociate, and break down. Of the constituent materials of the workpiece 110, granular materials P such as granular SAP 12 descend and pass through the screen F, settling below the screen F, while coarse pieces and fibrous materials LF such as pulp fibers 11 and sheets 20 remain above the screen F without passing through it.

[0126] Thus, in this embodiment 2, a screen F is installed in the solvent treatment unit 510, the solvent 120 is filled to a level above the screen F, and the workpiece 110 is added above the screen F, immersing the workpiece 110 in petroleum-based dry cleaning solvent 120 with a specific gravity of 0.6 or more and 0.8 or less. Due to gravity caused by the difference in specific gravity between the solvent 120 and the workpiece 10, and because the granular material P such as SAP 12 of the absorbent body 10 is smaller in size than the pores of the screen F, the granular material P is settled below the screen F, while the coarse pieces and fibrous material LF such as pulp fibers 11 and sheets 20 remain above the screen F. Therefore, the granular material P such as SAP 12 that has settled below the screen F and the coarse pieces and fibrous material LF such as pulp fibers 11 and sheets 20 that remain above the screen F are separated. Therefore, granular materials P such as SAP12 and coarse fragments / fibrous materials LF such as pulp fibers 11 and sheets 20 can be recovered separately.

[0127] In the treatment tank of the solvent treatment unit 510, granular material P such as SAP 12 that has settled below the screen F is discharged to the outside of the solvent treatment unit 510 together with the solvent 120 and recovered. After being filtered in the filtration unit 562 to remove the solvent 120, it is sent to the drying unit 550, which is equipped with drying means such as a heater, a vacuum pump, and a fan.

[0128] Coarse fragments and fibrous materials LF, such as pulp fibers 11 and sheets 20, that remain above screen F are recovered by being scraped, scooped up, or wound up from the solvent 120 and discharged to the outside of the solvent treatment area 510. The coarse fragments and fibrous materials LF, such as pulp fibers 11 and sheets 20, discharged from the solvent treatment area 510 are transported to a drying area 550 equipped with drying means such as a heater, a vacuum pump, and a fan, where they are dried by hot air drying, vacuum drying, etc. The recovered and dried coarse fragments and fibrous materials LF, such as pulp fibers 11 and sheets 20, are then converted into solid fuel, as in Example 1. Furthermore, when implementing the present invention, coarse fragments and fibrous materials LF such as pulp fibers 11 and sheets 20 that remain above screen F may be discharged to the outside along with the solvent 120 using airflow or liquid flow, filtered in a filtration section to remove the solvent 120, and then supplied to the drying section 550.

[0129] Incidentally, the inventors have been investigating various solvents 120 shown in Table 1 to dissolve the adhesive of the workpiece 110. In this study, a diaper was used as the absorbent material to be treated (110), and it was immersed in various solvents shown in Table 1 (the amount of solvent 120 used was consistent). To immerse the material 110 in the solvent 120, the diaper was laid flat and placed in a container. A sufficient amount of solvent was added to completely submerge the diaper, and the mixture was stirred.

[0130] [Table 1]

[0131] In any of the solvents 120 shown in Table 1, when the workpiece 110 was added and the solvent 120 was stirred, the adhesive in the workpiece 110 dissolved in the solvent 120, causing the workpiece 110 to decompose and break down, and its constituent materials to scatter. Here, for each solvent 120, the penetration of the solvent 120 into the workpiece 110 when the workpiece 110 was immersed in the solvent 120 was visually confirmed and evaluated on a three-point scale: good (A), acceptable (B), and unacceptable (C). Furthermore, the constituent materials such as the sheet 20 (PP / PE), pulp fibers 11, and SAP 12, which were scattered and separated from the workpiece 110 after immersion in the solvent 120, were visually inspected for any remaining adhesive, and the solubility of the adhesive was evaluated in three stages: no adhesive residue: good (A), some adhesive residue: good (B), and a large amount of adhesive residue: poor (C). Furthermore, the extracted sheet 20, pulp fibers 11, SAP 12, and other constituent materials were air-dried and evaluated on a three-point scale: excellent quick-drying properties: good (A), good quick-drying properties: good (B), and poor quick-drying properties: poor (C).

[0132] Furthermore, the odor of solvent 120 was evaluated on a three-point scale: no noticeable odor (A), a faint odor that could be detected (B), and a strong odor (C). In addition, the residual odor of solvent 120 was checked on the constituent materials such as the removed and dried sheet 20, pulp fibers 11, and SAP 12, and evaluated on a three-point scale: no noticeable odor (A), a faint odor that could be detected (B), and a strong residual odor (C).

[0133] In addition, the color residue of the solvent 120 on the constituent materials such as the removed and dried sheets 20, pulp fibers 11, and SAP 12 was visually inspected and evaluated in three stages: no discoloration: good (A), slight discoloration but hardly noticeable: acceptable (B), and noticeable discoloration: unacceptable (C). Furthermore, changes due to oxidative degradation of solvent 120 were examined and evaluated in three stages: good (A) for those that did not discolor or harden and were resistant to oxidative degradation, good (B) for those with slight discoloration or hardening, and poor (C) for those that discolored or hardened and were prone to oxidative degradation. Furthermore, the changes in properties of the constituent materials such as the removed and dried sheet 20, pulp fibers 11, and SAP 12 were evaluated in three stages: no change in properties for any of the constituent materials: good (A), slight changes in properties that are hardly noticeable: good (B), and changes in properties that are unsuitable for reuse: poor (C).

[0134] As shown in Table 1, paraffin-containing petroleum solvents such as Dry Solvent High Soft and Cleaning Solvent NW-S, as well as halogenated hydrocarbon solvents such as tetrachloroethylene and trichloroethylene, used as dry cleaning solvents, all exhibited good penetration into the workpiece 110, sufficiently dissolving the adhesive in the workpiece 110 without leaving any adhesive residue, and also had good quick-drying properties. In particular, the separated and recovered constituent materials did not retain the odor or color of the solvent 120, and furthermore, the solvent 120 was less prone to oxidative degradation, making it suitable for reuse, and it did not alter the constituent materials of the workpiece 110.

[0135] In contrast, while kerosene showed good penetration into the workpiece 110 and good solubility of the adhesive, it was inferior to petroleum-based solvents and halogenated hydrocarbon solvents such as tetrachloroethylene and trichloroethylene used in dry cleaning in terms of adhesive quick-drying, odor retention, color retention, and oxidative degradation of the solvent 120. Therefore, for solvent 120, it is preferable to use petroleum-based solvents used in dry cleaning, or halogenated hydrocarbon solvents such as tetrachloroethylene and trichloroethylene.

[0136] In other words, kerosene and similar solvents have a distinctive, strong odor, and even after drying, the characteristic odor of solvent 120 remains in the constituent materials such as sheet 20, pulp fibers 11, and SAP 12. Furthermore, they are prone to oxidation and hardening in the air, making them unsuitable for repeated use due to their susceptibility to oxidative degradation. In contrast, petroleum-based solvents containing paraffin, which are used in dry cleaning solvents, or halogenated hydrocarbon solvents such as tetrachloroethylene and trichloroethylene, do not have the odor of solvent 120, offer good handling and working environment, and do not leave any residual odor of solvent 120 in the constituent materials such as sheet 20, pulp fibers 11, and SAP 12. Therefore, they are suitable for reuse in a wide range of applications, and the recovered constituent materials such as sheet 20, pulp fibers 11, and SAP 12 are of high quality. Moreover, these solvents themselves are less prone to oxidative degradation, making them suitable for repeated use, reducing the cost of wastewater disposal, and resulting in a low-cost use of solvent 120.

[0137] Furthermore, according to the inventors' experimental research, halogenated hydrocarbon tetrachloroethylene is particularly suitable as a solvent 120 for separating the pulp fibers 11 and sheet 20 from the SAP 12. Specifically, in the halogenated hydrocarbon tetrachloroethylene solvent 120, granular SAP 12 floats to the surface, and by utilizing the flotation of SAP 12 and the screen F, the pulp fibers 11 and sheet 20 from SAP 12 can be separated quickly, efficiently, and with high precision, with low load and energy savings on the SAP 12. As a result, high-quality SAP 12 can be recovered, and the solid fuel 30 obtained by solidifying the sheet 20 and pulp fibers 11, etc., from which the SAP 12 has been separated, is also of high quality.

[0138] As described above, the method for recycling absorbent articles according to the above embodiment comprises a solvent treatment step (step S1) in which an unused absorbent article (object to be treated 110), which is made by joining a sheet 20 containing pulp fibers 11 and SAP 12 as absorbents 10 with an adhesive, is immersed in a solvent 120 to dissolve the adhesive in the solvent 120; a separation and recovery step (step S2) in which the absorbent article (object to be treated 110), from which the adhesive has been dissolved and removed, is separated and recovered into the sheet 20 and pulp fibers 11 and the SAP 12; and a drying step (step S3) in which the separated and recovered constituent materials, the sheet 20 and pulp fibers 11 and the SAP 12, etc., are dried.

[0139] According to the above embodiment of the method for recycling absorbent articles, the adhesive joining the components of an unused absorbent article (object to be processed 110) is dissolved in solvent 120 and removed from the absorbent article (object to be processed 110), thereby dismantling the absorbent article (object to be processed 110) and separating and recovering the sheet 20, pulp fibers 11, and SAP 12. As the adhesive of the absorbent article (object to be processed 110) is dissolved and removed, the absorbent article (object to be processed 110) is easily dismantled, and its constituent materials, the sheet 20, pulp fibers 11, and SAP 12, become easily separated. Therefore, it is possible to improve the recovery rate of SAP 12 and the like. In particular, by removing the adhesive from the absorbent article (processed material 110), the sheet 20 and pulp fibers 11, which are the constituent materials of the absorbent article (processed material 110), and the SAP 12 can be accurately separated and recovered without much effort, without requiring the application of large amounts of energy to pulverize or finely grind the SAP 12. Even when the pulp fibers 11 and sheet 20 are converted into solid fuel, the proportion of SAP 12 is low, and the SAP 12 is not inactivated, resulting in a high-quality solid fuel 30 with low impurities such as moisture, salt, and ash, and a high calorific value. Furthermore, the SAP 12 separated from the pulp fibers 11 and sheet 20 can be separated and recovered while maintaining its original properties as the absorbent body 10 of the absorbent article without pulverization or fine grinding, and since the adhesive is also removed, it is suitable for material recycling and also suitable for recycling the absorbent article as the absorbent body 10. Thus, according to the method for recycling absorbent articles of the above embodiment, high-quality recycled products can be obtained from unused absorbent articles.

[0140] Furthermore, prior to the drying process (step S3), the constituent materials of the absorbent article are separated and recovered into the sheet 20, pulp fibers 11, and SAP 12. Since the constituent materials of the absorbent article (processed material 110) are separated and recovered in a wet manner, it is possible to separate and recover the constituent materials with high separation accuracy under conditions that place a low load on the constituent materials and save energy, compared to the dry method.

[0141] In other words, according to the absorbent article recycling method of the above embodiment, the separation and recovery step (step S2) involves immersing the absorbent article (object to be processed 110) in the solvent 120 and separating it into the sheet 20 and pulp fibers 11 and the SAP 12 in the solvent 120. Therefore, the constituent materials of the absorbent article (object to be processed 110) that has been dismantled in the solvent 120 in which the adhesive has been dissolved are separated using gravity, centrifugal force, specific gravity difference, etc., and filtration separation using a screen F, etc. As a result, since the separation is wet, the sheet 20 and pulp fibers 11 and the SAP 12 can be separated accurately under low-load and energy-saving conditions. Consequently, by being able to separate the sheet 20 and pulp fibers 11 and the SAP 12 accurately under low-cost, energy-saving, and low-load conditions, the absorbent material can be recovered in high quality at low cost and energy saving, and the recovery rate can be improved.

[0142] If the solvent 120 used to dissolve the adhesive in the absorbent article (object to be treated 110) is a petroleum-based and / or halogenated hydrocarbon-based dry cleaning solvent, it is less susceptible to oxidative degradation and suitable for repeated reuse, and the odor of the solvent 120 is less likely to remain in the separated and recovered constituent materials such as SAP 12. Therefore, costs can be reduced, and the separated and recovered SAP 12 can be recycled into a wide range of uses without being limited.

[0143] The solvent 120 used to immerse the absorbent article (object to be treated 110), that is, the solvent 120 used to dissolve the adhesive of the solvent-absorbing article (object to be treated 110), has a specific gravity in the range of 0.7 to 1.5, preferably in the range of 0.7 to 0.8. When the absorbent article (object to be treated 110) is immersed in the solvent 120, the SAP 12 will settle in the solvent 120. Therefore, in the solvent 120, the sheet 20 and pulp fibers 11 and the SAP 12 can be accurately separated under low-impact and energy-saving conditions by settling due to the difference in specific gravity (gravity) and filtration separation using a screen F, etc. Consequently, by accurately separating the sheet 20 and pulp fibers 11 and the SAP 12 under low-cost, energy-saving, and low-impact conditions, the SAP 12 can be recovered in high quality at low cost and energy-saving conditions, and the recovery rate can be improved.

[0144] If the solvent 120 used to immerse the absorbent article (object to be treated 110), that is, the solvent 120 used to dissolve the adhesive of the solvent-absorbing article (object to be treated 110), has a specific gravity in the range of 1.6 to 1.8, then the SAP 12 will float in the solvent 120 when the absorbent article (object to be treated 110) is immersed in the solvent 120. Therefore, in the solvent 120, the sheet 20 and pulp fibers 11 and the SAP 12 can be accurately separated under low-impact and energy-saving conditions by filtration separation using the difference in specific gravity (gravity) and a screen F, etc. Consequently, by accurately separating the sheet 20 and pulp fibers 11 and the SAP 12 under low-cost, energy-saving, and low-impact conditions, the SAP 12 can be recovered in high quality at low cost and energy-saving conditions, and the recovery rate can be improved.

[0145] According to the above embodiment of the method for recycling absorbent articles, by further including an adhesive separation and recovery step (step S4) in which the solvent 120 in which the adhesive is dissolved is distilled and the adhesive is separated and recovered, the adhesive of the absorbent article can be recycled, thus enabling more effective use of resources. In addition, the solvent 120 separated from the adhesive in the adhesive separation and recovery process (step S4) is reused as the solvent 120 used to immerse the absorbent article (object to be treated 110) in the solvent treatment process (step S1), thus conserving resources and reducing costs.

[0146] In addition, according to the above embodiment of the method for recycling absorbent articles, by including a solid fuel conversion step (step S5) in which the remaining sheet 20 and pulp fibers 11 from which the SAP 12 has been separated are converted into solid fuel, the resulting solid fuel 30 does not absorb water and swell, and has low levels of impurities such as moisture, salt, and ash, and therefore has a high calorific value, as the SAP 12 has been separated and the adhesive has been removed. Thus, a high-quality solid fuel 30 can be obtained.

[0147] Furthermore, the above embodiment can also be considered as an invention of an absorbent article recycling device comprising: a solvent treatment unit 510 that immerses an unused absorbent article (object to be processed 110), which is made by joining a sheet 20 containing pulp fibers 11 and SAP 12 as absorbent material 10 with an adhesive, in a solvent 120 to dissolve the adhesive in the solvent 120; a separation and recovery means using a screen F or the like to separate and recover the absorbent article (object to be processed 110) from which the adhesive has been dissolved and removed into the sheet 20 and pulp fibers 11 and SAP 12; and a drying means using a heater, a vacuum pump, a fan or the like to dry the separated and recovered constituent materials, the sheet 20 and pulp fibers 11 and SAP 12.

[0148] According to the absorbent article recycling apparatus of the above embodiment, the adhesive joining the components of the unused absorbent article (object to be processed 110) is dissolved in the solvent 120 and removed from the absorbent article (object to be processed 110), thereby dismantling the absorbent article (object to be processed 110) and separating and recovering the sheet 20, pulp fibers 11, and SAP 12. As the adhesive of the absorbent article (object to be processed 110) is dissolved and removed, the absorbent article (object to be processed 110) is easily dismantled, and its constituent materials, the sheet 20, pulp fibers 11, and SAP 12, become easily separated. Therefore, it is possible to improve the recovery rate of SAP 12 and the like. In particular, by removing the adhesive from the absorbent article (processed material 110), the sheet 20 and pulp fibers 11, which are the constituent materials of the absorbent article (processed material 110), and the SAP 12 can be accurately separated and recovered without much effort, without requiring the application of large amounts of energy to pulverize or finely grind the SAP 12. Even when the pulp fibers 11 and sheet 20 are converted into solid fuel, the proportion of SAP 12 is low, and the SAP 12 is not inactivated, resulting in a high-quality solid fuel 30 with low impurities such as moisture, salt, and ash, and a high calorific value. Furthermore, the SAP 12 separated from the pulp fibers 11 and sheet 20 can be separated and recovered while maintaining its original properties as the absorbent body 10 of the absorbent article without pulverization or fine grinding, and since the adhesive is also removed, it is suitable for material recycling and also suitable for recycling the absorbent article as the absorbent body 10. Thus, according to the method for recycling absorbent articles of the above embodiment, high-quality recycled products can be obtained from unused absorbent articles.

[0149] Furthermore, prior to drying by the drying means, the constituent materials of the absorbent article are separated and recovered into the sheet 20, pulp fibers 11, and SAP 12. Since the constituent materials of the absorbent article (processed material 110) are separated and recovered in a wet manner, it is possible to separate and recover the constituent materials with high separation accuracy under conditions that place a low load on the constituent materials and save energy, compared to the dry method.

[0150] In other words, according to the absorbent article recycling apparatus of the above embodiment, the separation and recovery means separates the absorbent article (object to be processed 110) into the sheet 20 and pulp fibers 11 and the SAP 12 in the solvent 120 after immersion in the solvent 120. Therefore, the constituent materials of the absorbent article (object to be processed 110) that has been dismantled in the solvent 120 in which the adhesive has been dissolved are separated using gravity, centrifugal force, and filtration separation using a screen F, etc. Therefore, since the separation is wet, the sheet 20 and pulp fibers 11 and the SAP 12 can be separated accurately under low-load and energy-saving conditions. Consequently, by being able to separate the sheet 20 and pulp fibers 11 and the SAP 12 accurately under low-cost, energy-saving, and low-load conditions, the SAP 12 can be recovered in high quality at low cost and energy-saving, and the recovery rate can be improved.

[0151] Furthermore, the absorbent article recycling apparatus of the above embodiment is further equipped with a distillation unit 530 as an adhesive separation and recovery means that distills the solvent 120 in which the adhesive has dissolved and separates and recovers the adhesive, thereby enabling the recycling of the adhesive in the absorbent article and allowing for even more effective use of resources. In addition, by providing a solvent circulation path 540 that allows the solvent 120 separated from the adhesive by the adhesive separation means to be reused as a solvent 120 for immersion treatment of absorbent articles (objects to be treated 110) in the solvent treatment area 510, the solvent 120 separated from the adhesive by the adhesive separation and recovery means is reused as a solvent 120 for immersion treatment of absorbent articles (objects to be treated 110), thereby conserving resources and reducing costs.

[0152] Furthermore, according to the absorbent article recycling apparatus of the above embodiment, the remaining sheet 20 and pulp fibers 11 from which the SAP 12 has been separated are converted into solid fuel by a solid fuel conversion means using a molding machine and a cooling machine, etc. As a result, the obtained solid fuel 30 does not absorb water and swell, and has low levels of impurities such as moisture, salt, and ash, and a high calorific value because the SAP 12 has been separated and the adhesive has been removed. Therefore, a high-quality solid fuel 30 can be obtained.

[0153] In the above embodiment, a solvent treatment step (step S1) is performed in which the workpiece 110 is immersed in the solvent 120 to dissolve the adhesive that was joining the components of the workpiece 110 in the solvent 120, followed by a separation and recovery step (step S2) in which the sheet 20 and pulp fibers 11 and SAP 12 are separated and recovered individually, and then a drying step (step S3) is performed in which the separated and recovered components are dried individually or together.

[0154] However, when implementing the present invention, the constituent materials of the workpiece 110 from which the adhesive has been removed by immersion in the solvent 120 may be dried and then individually separated and recovered into the sheet 20, the pulp fibers 11, and the SAP 12. In other words, the recycling method according to the modified example includes a solvent treatment step (step S1) in which the adhesive joining the components of the workpiece 110 is dissolved in a solvent 120, a drying step in which the components of the workpiece 110 from which the adhesive has been removed are dried, and a separation and recovery step in which the dried components of the workpiece 110 are separated and recovered into a sheet 20, pulp fibers 11 and SAP 12. In this method, the drying step is performed after the solvent treatment step (step S1) to dry the components of the workpiece 110, and then the separation and recovery step is performed to separate and recover the components of the workpiece 110 into a sheet 20, pulp fibers 11 and SAP 12.

[0155] Furthermore, the recycling apparatus according to the modified example includes a solvent treatment unit 510 that immerses the workpiece 110 in a solvent to dissolve the adhesive in the solvent 120, a drying means for drying the constituent materials of the workpiece 110 from which the adhesive has been removed by dissolving the adhesive in the solvent 120, and a separation and recovery means for separating and recovering the dried constituent materials into a sheet 20, pulp fibers 11, and SAP 12.

[0156] In this modified example, the workpiece 110 is immersed in the solvent 120 in the solvent treatment unit 510, and after the adhesive has dissolved into the solvent 120, the constituent materials of the workpiece 110 are collected together and dried. The materials of the workpiece 110 may be dried by discharging and collecting the materials of the workpiece 110 from the solvent treatment unit 510 and drying them in another location, or by discharging the solvent 120 in which the adhesive has been dissolved from the treatment tank of the solvent treatment unit 510 and drying the remaining materials of the workpiece 110 in that treatment tank. Furthermore, the solvent 120 discharged and recovered at this time is also distilled in the distillation section 530 to precipitate the adhesive as a solid, and the solvent 120 and the adhesive are separated and recovered individually. The solvent 120 separated from the adhesive is reused again in the solvent treatment section 510 as solvent 120 to dissolve the adhesive.

[0157] After the adhesive has been removed from the treated material 110, it is dried and desolvented, and then separated and recovered into the sheet 20, pulp fibers 11, and SAP 12. As a means of separating and recovering each component material, separation can be achieved by utilizing differences in dimensions, specific gravity (bulk density), resistance, drop, etc., and for example, a screen F or the like can be used, as in the above embodiment. Alternatively, separation can be achieved using airflow. By applying an airflow to the constituent materials of the dried workpiece 110, the differences in specific gravity and resistance of the constituent materials can be used to move and separate them. Alternatively, a wind classifier such as a cyclone can be used. In particular, the modified method allows for the separation of the constituent materials of the absorbent article in a dry state, thereby improving the separation accuracy.

[0158] Incidentally, the absorbent articles described above are based on the premise that the sheets 20 are joined by heat sealing using hot melt adhesive. However, by joining the sheets 20 containing the absorbent material 10 by ultrasonic sealing, which melts and joins the sheets 20 using ultrasonic vibration and pressure, the effort and number of processes for recycling the absorbent articles can be simplified, and the recovery rate of SAP 12, a constituent material of the absorbent articles, can be improved.

[0159] Furthermore, when implementing the present invention, the configuration, composition, blending, components, shape, quantity, material, size, manufacturing method, etc., of the other parts of the method for recycling absorbent articles and the recycling apparatus are not limited to this embodiment, its modifications, and examples. Also, not all of the numerical values ​​given in this embodiment, its modifications, and examples represent critical values; some values ​​represent suitable values ​​for implementation, and therefore, slightly changing the above numerical values ​​does not negate implementation. [Explanation of Symbols]

[0160] 10 absorbent material 11 Pulp Fibers 12 Superabsorbent Polymer (SAP) 20 sheets 110. Materials to be processed (absorbent articles)

Claims

1. A solvent treatment step involves immersing an unused absorbent article, which is made by joining sheets containing a highly absorbent polymer and pulp fibers as absorbents with an adhesive, in a solvent to dissolve the adhesive in the solvent. A separation and recovery step is performed to separate and recover the absorbent article from which the adhesive has been dissolved and removed into the superabsorbent polymer, the sheet, and the pulp fibers. A drying step of drying the constituent material of the absorbent article from which the adhesive has been dissolved and removed. It is equipped with, A method for recycling absorbent articles, characterized in that the solvent used to immerse the absorbent article is a petroleum-based and / or halogenated hydrocarbon-based dry cleaning solvent.

2. The method for recycling absorbent articles according to claim 1, characterized in that the solvent used for immersing the absorbent article has a specific gravity in the range of 0.7 to 1.

5.

3. The method for recycling absorbent articles according to claim 1, characterized in that the solvent used to immerse the absorbent article has a specific gravity in the range of 1.6 to 1.

8.

4. The method for recycling an absorbent article according to claim 1, characterized in that the separation and recovery step separates the absorbent article into the superabsorbent polymer, the sheet, and the pulp fibers in the solvent in which the absorbent article is immersed.

5. Furthermore, the method for recycling absorbent articles according to claim 1 is characterized by comprising an adhesive separation and recovery step of distilling the solvent in which the adhesive has dissolved and separating and recovering the adhesive.

6. The method for recycling absorbent articles according to claim 5, characterized in that the solvent separated from the adhesive in the adhesive separation and recovery step is reused as a solvent for immersing the absorbent article in the solvent treatment step.

7. Furthermore, the method for recycling absorbent articles according to claim 1 is characterized by comprising a solid fuel production step of converting the sheet and pulp fibers separated from the superabsorbent polymer into solid fuel.

8. A solvent treatment unit is used to dissolve the adhesive in a solvent by immersing an unused absorbent article, which is made by joining sheets containing a highly absorbent polymer and pulp fibers as absorbents with an adhesive, in a solvent. A separation and recovery means for separating and recovering the absorbent article from which the adhesive has been dissolved and removed into the superabsorbent polymer, the sheet, and the pulp fibers, A drying means for drying the constituent material of the absorbent article from which the adhesive has been dissolved and removed. It is equipped with, The apparatus for recycling absorbent articles is characterized in that the solvent used to immerse the absorbent articles is a petroleum-based and / or halogenated hydrocarbon-based dry cleaning solvent.

9. The absorbent article recycling apparatus according to claim 8, characterized in that the solvent used for immersing the absorbent article has a specific gravity in the range of 0.7 to 1.

5.

10. The absorbent article recycling apparatus according to claim 8, characterized in that the solvent used for immersing the absorbent article has a specific gravity in the range of 1.6 to 1.

8.

11. The recycling apparatus for absorbent articles according to claim 8, characterized in that the separation and recovery means separates the absorbent article into the superabsorbent polymer, the sheet, and the pulp fibers in the solvent in which the absorbent article is immersed.

12. Furthermore, the apparatus for recycling absorbent articles according to claim 8 is characterized by comprising an adhesive separation and recovery means for distilling the solvent in which the adhesive has dissolved and separating and recovering the adhesive.

13. Furthermore, the recycling apparatus for absorbent articles according to claim 12 is characterized by comprising a solvent circulation path that allows the solvent separated from the adhesive by the adhesive separation means to be reused as a solvent for immersing the absorbent article in the solvent treatment section.

14. Furthermore, the absorbent article recycling apparatus according to claim 8 is characterized by comprising a means for converting the sheet and pulp fibers separated from the superabsorbent polymer into solid fuel.

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