Method for treating paper diaper

Abstract

This method for treating a paper diaper involves: a step for crushing a used paper diaper and washing same; and a pulp content reduction treatment step for reducing the pulp content ratio of a pulp-containing plastic fraction produced in the previous step by fracturing treatment and sorting treatment. The sorting treatment is performed by wind power sorting treatment, sieving sorting treatment, wet specific gravity sorting treatment, or the like.

Description

How to dispose of disposable diapers

[0001] The present invention relates to a method for disposing of disposable diapers, particularly used disposable diapers. Note that in the present invention, disposable diapers include not only tape-type and pants-type disposable diapers but also urine absorption pads.

[0002] Commonly used tape-type or pants-type disposable diapers include a surface material, three-dimensional gathers to prevent leakage, a water-absorbing material, a waterproof material (exterior material), an elastic material, etc. Tape-type diapers also include a fastening tape.

[0003] The surface material is the surface that comes into direct contact with the skin and is made of polyester or polyolefin nonwoven fabric. The gathers, exterior material (waterproof material), and tape are made of polyolefin film. The absorbent material is made of cotton-like pulp and polymer absorbent material. The stretch material is made of polyurethane.

[0004] The parts of the disposable diaper are bonded together with adhesives such as hot melt adhesives.

[0005] As the elderly population increases, the demand for disposable diapers is increasing, and the disposal of used disposable diapers that are discarded as waste has become a serious social issue.

[0006] Patent Document 1 describes a method for treating used disposable diapers to recover pulp, in which the used disposable diapers are decomposed into their respective materials in a separation tank, and separated into pulp and film and pulp-containing wastewater, the former being used as fuel, and pulp being recovered from the latter (pulp-containing wastewater) and used as a raw material for manufacturing cardboard. However, Patent Document 1 does not describe the specific configuration of the separation tank or the separation device, nor does it describe specifically how pulp is recovered from the pulp-containing wastewater.

[0007] Patent document 2 describes a bag-breaking device that can break bags containing used paper diapers and crush the used paper diapers, and that has blades attached to the inner surface of the rotating tub of a drum-type washing machine.

[0008] JP 2019-35162 A Patent No. 7359262 A

[0009] The present invention aims to provide a method for disposing of used disposable diapers, in which the amount of pulp and polymeric water-absorbing material adhering to the film can be reduced, in a method for disassembling used disposable diapers and separating and recovering the plastic film.

[0010] One aspect of the present invention is as follows: [1] A method for treating disposable diapers, comprising: a step of crushing and washing used disposable diapers; and a step of reducing the pulp content of the pulp-containing plastic fraction produced in this step by crushing and sorting the fraction.

[0011] [2] The method for treating disposable diapers according to [1], wherein in the pulp content reduction treatment step, a sorting treatment is carried out after the shredding treatment.

[0012] [3] The method for treating disposable diapers according to [2], wherein the sorting process is carried out by at least one of a wind sorting process, a sieving sorting process, and a wet specific gravity sorting process.

[0013] [4] The disposable diaper processing method according to [3], wherein the sorting process is carried out by one selected from the group consisting of an air sorting process followed by a wet specific gravity sorting process, a sieving sorting process followed by a wet specific gravity sorting process, a sieving sorting process followed by an air sorting process, and a process in which the sieving sorting process, the air sorting process, and the wet specific gravity sorting process are carried out in this order.

[0014] [5] The method for treating disposable diapers according to [4], wherein at least one of dehydration, drying, and compression is carried out after the sorting process.

[0015] [6] The disposable diaper processing method according to [1], wherein in the pulp content reduction treatment step, a crushing treatment is carried out after the sorting treatment.

[0016] [7] The method for treating disposable diapers according to [6], wherein the sorting process is a sieving sorting process.

[0017] [8] The method for treating disposable diapers according to [6], wherein the disposable diapers are subjected to air sorting or wet gravity sorting after the shredding process.

[0018] [9] The method for treating disposable diapers according to [8], wherein at least one of dehydration, drying, and compression is carried out after the air sorting process or the water specific gravity sorting process.

[0019]

[10] The method for treating disposable diapers according to any one of [1] to [9], wherein the step of crushing and washing used disposable diapers is carried out using a bag-breaking device.

[0020]

[11] The bag-breaking device is a bag-breaking device using a drum-type washing machine having a water tub for storing wash water, a bottomed cylindrical rotating tub that is supported in the water tub so that it can rotate freely with its rotation axis approximately horizontal and that stores laundry, bag-breaking blades provided on the inner surface of the rotating tub, and a motor that rotates the rotating tub, and the method for treating disposable diapers of

[10] includes the steps of: feeding used disposable diapers, chemicals, and water into the bag-breaking device; rotating the rotating tub to crush the used disposable diapers; supplying cleaning water to wash the crushed material; and then increasing the rotation speed of the rotating tub to spin-dry the material.

[0021] According to the method for treating disposable diapers of the present invention, the amount of pulp and polymeric water-absorbing material adhering to the film is small.

[0022] The smaller the amount of pulp or polymeric water-absorbing material attached to the film, the higher the purity of the recovered film, which allows for a wider range of reuse applications. Furthermore, the film is easier to dehydrate and dry, and when the recovered film is used as fuel, the amount of heat generated by combustion can be increased.

[0023] Fig. 2 is a cross-sectional view showing an example of a bag-breaking device. Fig. 3 is a perspective view showing the structure of a blade portion of the bag-breaking device.

[0024] The disposable diaper disposal method according to the embodiment of the present invention will be described in detail below with reference to the drawings. The disposable diapers to be disposed of in the present invention are usually used disposable diapers contaminated with feces and urine, but are not limited to used disposable diapers, and may also be unused disposable diapers, defective disposable diapers discarded from factories, or disposable diapers that have absorbed water or mud due to disasters or the like.

[0025] In the present invention, disposable diapers are first crushed and washed (pretreatment step). A suitable pretreatment method for disposable diapers is to add water, crush the disposable diapers, wash them, and then dehydrate them. Preferably, the crushing, washing, and dehydration are performed using the bag-breaking device described in Patent Document 2.

[0026] The bag-breaking device of Patent Document 2 is a bag-breaking device for breaking waste storage bags, and is a bag-breaking device that uses a drum-type washing machine having a water tank for storing wash water, a bottomed cylindrical rotating tub that is supported in the water tank so that it can rotate freely with its rotation axis approximately horizontal and that holds laundry, and a motor that rotates the rotating tub, and is characterized in that a blade for breaking bags is provided on the inner surface of the rotating tub.

[0027] FIG. 1 is a vertical cross-sectional view of a bag-breaking device (a drum-type washing machine equipped with a blade 12) disclosed in Patent Document 2.

[0028] 1, a water tub 2 is supported within a housing 1 via suspension support members (not shown), and a cylindrical rotating tub 3 with a bottom is disposed within the water tub 2. A number of dewatering holes (not shown) are provided on the circumferential surface of the rotating tub 3. A mesh-like ventilation section is also provided on the bottom surface (rear wall surface) of the rotating tub 3.

[0029] Water tub 2 and rotating tub 3 are supported with their open ends facing the front of housing 1 and their bottoms facing the rear of housing 1, tilting downward from the horizontal toward the rear (although not shown, water tub 2 and rotating tub 3 may also be supported so that they are approximately horizontal facing from the front to the rear). Rotating tub 3 is driven to rotate by motor 5 via shaft 4.

[0030] A door 6 is provided on the housing 1 opposite the open end of the rotatable tub 3. By opening the door 6, waste storage bags can be inserted into or removed from the rotatable tub 3. A bellows 7 made of a flexible elastic material is disposed around the laundry entrance 2a of the water tub 2. When the door 6 is closed, one end of the bellows 7 is pressed against the inner surface of the door 6, preventing water from splashing out of the water tub 2.

[0031] The inner peripheral wall of the rotating tub 3 is provided with a plurality of protrusions 11 (for example, 3 to 6 protrusions), and by rotating the rotating tub 3 at a low speed, the waste storage bags and the waste drawn out from them can be hooked onto the protrusions 11 and lifted upward.

[0032] The protrusions 11 are provided as ridges extending in a direction parallel to the rotation axis of the rotary tub 3. The protrusions 11 are provided with blades 12 for breaking bags.

[0033] 2, the cross section of the protrusion 11 in the circumferential direction of the rotating tub 3 is substantially triangular. More specifically, the protrusion 11 is a substantially triangular shape that narrows as it rises from the inner circumferential surface of the rotating tub 3.

[0034] The blade 12 is provided so as to stand from the top of the protrusion 11 toward the axial center of the rotating tub 3. The base end 12a of the blade 12 is fixed to the protrusion 11 by a fixing means 13 such as a bolt or a rivet. Alternatively, the blade 12 may be flat and attached to the protrusion 11 by a separate attachment member (for example, a pair of plates).

[0035] The tip end of the blade 12 in the rising direction is a sawtooth blade 12b. However, the shape of the blade may be other than sawtooth, for example, it may be claw-shaped, needle-shaped, or the like.

[0036] In FIG. 1, a plurality of blades 12 are attached at intervals to one protrusion 11, but a single long blade may be attached.

[0037] The blade 12 is preferably made of a highly corrosion-resistant metal such as stainless steel, titanium, or a titanium alloy.

[0038] As water supply paths for supplying water into the water tub 2, a water supply port 14, a water supply valve 15, a first water supply path 16, a detergent addition section 17, and a second water supply path 18 are provided.

[0039] A drainage path 8 for draining water from the water tub 2 is provided below the water tub 2, and a drainage valve 9 for opening and closing the path is provided midway along the drainage path 8. When water, detergent, etc. are stored in the water tub 2 with the drainage valve 9 closed, the spin tub 3 becomes a laundry chamber.

[0040] Furthermore, when drain valve 9 is opened, the water, detergent, etc. stored in water tub 2 is drained through drainage path 8, and rotating tub 3 is rotated at high speed, the contents are pressed against the side of rotating tub 3 by centrifugal force. At this time, the moisture contained in the contents escapes between water tub 2 and rotating tub 3 through multiple dehydration holes provided on the side of rotating tub 3 and is drained through drainage path 8. In this way, rotating tub 3 also functions as a dehydration chamber.

[0041] The rotating tub 3 is also structured so that hot air is circulated and blown through an inlet 19, an air passage 20, a heater 21, an air blowing means 22, an air passage 23, and an outlet 24, and when hot air is blown, the rotating tub 3 also serves as a drying chamber.

[0042] The rotating tank 3 preferably has a diameter of 100 to 300 cm and a length of 100 to 300 cm, and is provided with a large number of small holes (dewatering holes) with a diameter of 5 to 15 mm on its circumferential surface (an opening ratio of the circumferential surface of about 10 to 30%).

[0043] To process disposable diapers contained in waste collection bags using this bag-breaking device, door 6 is opened and the waste collection bags are placed into rotatable tub 3. Door 6 is then closed, and rotatable tub 3 is rotated by motor 5. In this case, rotatable tub 3 may be rotated in one direction or may be rotated back and forth in the forward and reverse directions.

[0044] When the rotary tub 3 is rotated, the bags are torn by the blades 12, and the contained waste material is ejected from the bags. By rotating the rotary tub 3 back and forth, the bags can be torn efficiently.

[0045] To promote the disintegration of disposable diapers, water may be poured into the rotating drum 3, and the mixture may be stirred and mixed by heating and / or adding chemicals such as alkali, or the mixture may be heated and / or chemicals may be added while stirring and mixing. The heating means is preferably a means for heating the mixture to 80°C or higher by blowing in steam.

[0046] The water injection or chemical addition may be carried out at the beginning or after the waste storage bag is broken.

[0047] This tearing of the bags and crushing of the disposable diapers is carried out in a completely sealed state, so no odors or waste materials are released to the outside.

[0048] The chemical preferably contains a component that removes moisture (dehydrates) from the absorbent polymer (SAP) contained in the disposable diaper. Slaked lime and calcium chloride are suitable chemicals, but sodium salts, magnesium salts, organic acids (citric acid, oxalic acid), inorganic acids (nitric acid, sulfuric acid, hydrochloric acid), etc. may also be used.

[0049] The chemicals may contain a disinfectant component for sterilization. There are no particular restrictions on the disinfectant component, but an inexpensive one such as calcium hypochlorite (bleaching powder) is an example.

[0050] A surfactant may be used as part of the chemicals to promote the decomposition and cleaning of disposable diapers. Suitable surfactants include linear alkylbenzenes, higher alcohols, α-olefins, quaternary ammonium salts, fatty acids, and alpha-sulfo fatty acids. It is preferable to use 0.1 to 100 parts by weight, and more preferably 1 to 10 parts by weight, of the surfactant per 100 parts by weight of used disposable diapers.

[0051] In one embodiment of the present invention, the chemical is composed of slaked lime and calcium hypochlorite, and the mixing ratio is 80 to 98% slaked lime and 20 to 2% calcium hypochlorite. When the chemical is composed of slaked lime and calcium hypochlorite, it is preferable to use 0.1 to 20 parts by weight, especially 1 to 10 parts by weight, of slaked lime and calcium hypochlorite, and 50 to 1000 parts by weight, especially 100 to 500 parts by weight of water, per 100 parts by weight of used disposable diapers.

[0052] After the above-mentioned bag breaking and crushing processes have been carried out, the rotating tub 3 is rotated at high speed, leaving behind in the rotating tub 3 a plastic fraction consisting mainly of film and nonwoven fabric with pulp and polymer water absorbent material attached thereto, while the pulp and wastewater containing manure are discharged outside the bag breaking device through small holes and sent to the wastewater treatment process. Because the polymer water absorbent material is finely crushed in the bag breaking device, most of it is discharged together with the pulp and wastewater, but some remains in the rotating tub 3 together with the plastic fraction.

[0053] Thereafter, water is poured into the water tank 2 through the water supply port 14 to rinse away any residue remaining in the rotating tank 3. This rinsing may be performed by pouring water or by rinsing in a reservoir.

[0054] After rinsing, the rotary tub 3 is rotated at high speed to perform dewatering. The dewatered plastic fraction (including a small amount of pulp) is removed from the rotary tub 3 by opening the door 6. The moisture content of this plastic fraction is 20 to 70%, particularly 45 to 60%. After dewatering, when the dehydrated material is dried by applying hot air in a bag-breaking device, the moisture content of the plastic fraction is 20 to 50%, particularly 30 to 40%.

[0055] The pulp content of this plastic fraction is usually about 15% to 40% by dry weight, so depending on the requirements of the recycling destination, a pulp content reduction process is carried out to reduce the pulp content.

[0056] This pulp content reduction treatment is carried out by crushing and sorting the plastic fraction, and the following treatments (1) to (16) are particularly suitable, but not limited to these. (1) Crushing ⇒ Air sorting ⇒ Drying ⇒ Compression (2) Crushing ⇒ Air sorting ⇒ Compression (3) Crushing ⇒ Air sorting ⇒ Wet specific gravity sorting ⇒ Dehydration ⇒ Drying ⇒ Compression (4) Crushing ⇒ Sifting ⇒ Drying ⇒ Compression (5) Crushing ⇒ Sifting ⇒ Compression (6) Crushing ⇒ Sifting ⇒ Wet specific gravity sorting ⇒ Dehydration ⇒ Drying ⇒ Compression (7) Crushing ⇒ Wet specific gravity sorting ⇒ Dehydration ⇒ Drying ⇒ Compression (8) Sifting ⇒ Crushing ⇒ Drying ⇒ Compression (9) Sifting ⇒ Crushing ⇒ Compression (10) Sifting ⇒ Crushing ⇒ Air sorting ⇒ Drying ⇒ Compression (11) Sifting ⇒ Crushing ⇒ Air sorting ⇒ Compression (12) Sifting and sorting ⇒ Crushing ⇒ Air sorting ⇒ Wet specific gravity sorting ⇒ Dehydration ⇒ Drying ⇒ Compression (13) Sifting and sorting ⇒ Crushing ⇒ Wet specific gravity sorting ⇒ Dehydration ⇒ Drying ⇒ Compression (14) Crushing ⇒ Sifting and sorting ⇒ Air sorting ⇒ Drying ⇒ Compression (15) Crushing ⇒ Sifting and sorting ⇒ Air sorting ⇒ Compression (16) Crushing ⇒ Sifting and sorting ⇒ Air sorting ⇒ Wet specific gravity sorting ⇒ Compression

[0057] Among these processes (1) to (16), processes (1) to (7) and (14) to (16) in which the plastic fraction is first crushed are particularly preferred.

[0058] In one aspect of the present invention, the sorting process is carried out by at least one of air sorting, sieving, and wet gravity sorting.

[0059] In another aspect of the present invention, the sorting process is carried out by one selected from: an air sorting process followed by a wet specific gravity sorting process; a sieving sorting process followed by a wet specific gravity sorting process; a sieving sorting process followed by an air sorting process; or a process in which the sieving sorting process, the air sorting process, and the wet specific gravity sorting process are carried out in this order.

[0060] [Crushing of Plastic Fraction] The plastic fraction removed from the rotary tank 3 is compressed into lumps by the centrifugal force during centrifugal dehydration. Therefore, it is preferable to crush this plastic fraction.

[0061] The crushing of the bulk plastic fraction is preferably carried out by a crusher having a rotating shaft with blades arranged inside the machine casing. The crusher may be either a single-shaft crusher with one rotating shaft or a twin-shaft crusher with two rotating shafts. A single-shaft crusher has a rotating blade and a fixed blade arranged inside a punched metal outer body, and is configured so that only crushed material is discharged. In the case of a single-shaft crusher, the rotation direction may be reversed at predetermined intervals. In a twin-shaft crusher, two rotating shafts are arranged parallel and close to each other inside the machine casing. The material to be crushed is fed from above. The two rotating shafts rotate in opposite directions to bite into the material to be crushed.

[0062] When crushing the bulk plastic fraction, it is preferable that the plastic fraction is wet, but it can also be crushed in a dry state.

[0063] The crushing step is preferably carried out to adjust the size of the plastic fraction to pass through a punched metal having a hole diameter of 5 mm to 100 mm.

[0064] The pulp that is entangled in the fluff of the nonwoven fabric is easily physically separated from the film by crushing the plastic fraction.

[0065] <Sorting> Sorting can be carried out by one or more of air sorting, sieving, wet gravity sorting, and the like.

[0066] Alternatively, the pulp may be roughly separated by air sorting or sieving, and then subjected to wet gravity sorting.

[0067] <Wind sorting> A wind sorter is designed to blow air into the sorter and separate heavy and light materials by taking advantage of the difference in specific gravity. By adjusting the air volume, the discharge ratio of light and heavy materials can be fine-tuned.

[0068] It is preferable to adjust the moisture content of the pulp-containing plastic fraction to 20% to 60% before air sorting.

[0069] <Sieving> Sieving can be performed using a vibrating sieve, etc. In sieving, it is also preferable to adjust the moisture content of the pulp-containing plastic fraction to 20% to 60% before the sieving.

[0070] <Wet Gravity Separation> For wet gravity separation, a water tank type gravity separator or a water flow type gravity separator can be used.

[0071] A water tank-type gravity separator is equipped with a paddle at the top of the tank and a screw at the bottom. The material to be separated (plastic fraction) is placed in the middle of the tank, and the material that rises to the surface is scraped off with the paddle, while the material that sinks to the bottom is collected with the screw. Since no large water currents are generated, separation is essentially based solely on differences in specific gravity.

[0072] The water flow density separator is configured to generate a gentle and stable water flow and separate plastics at a separation point of specific gravity of 1.05 (adjustable) without using heavy liquid.

[0073] Regarding the water temperature when wet gravity sorting, the higher the temperature, the better the sorting efficiency, taking into account the melting point of the hot melt adhesive in disposable diapers. However, water at room temperature or below may also be used.

[0074] <Dehydrator> Examples of the dehydrator include a screw press, a centrifugal dehydrator, and a belt press.

[0075] The dehydrator may be a plastic compression granulator adapted for compression dehydration and drying.

[0076] To compress and dehydrate plastic fractions using a plastic compression granulator, the plastic fraction is introduced in a wet state, and compression and drying are carried out simultaneously. Specifically, the material to be compressed (plastic fraction) is transferred and introduced using a screw while water is being poured in. Then, the material is kneaded using two screws while utilizing frictional heat. The kneaded material is extruded while being heated by a heater attached to the discharge outlet, and is then cut into a semi-molten state using a cutter (propeller-shaped, four-blade).

[0077] The cut kneaded material is collected while being cooled by a cyclone.

[0078] When dehydration is carried out before drying, it is preferable to carry out dehydration so that the moisture content after dehydration is 70% or less, particularly 50% or less.

[0079] <Dryer> A ventilated box dryer is suitable as the dryer. This ventilated box dryer is a batch type dryer in which the material to be dried is placed on a box-shaped tray (with a mesh bottom) and placed inside the ventilated box dryer. Hot air at 100°C to 150°C (adjustable) is blown downward from above to dry the material.

[0080] <Compressor> As the compressor, a cylinder type compressor can be used in which the material to be treated is placed in a cylinder and compressed by pressing with a piston, but the compressor is not limited to this.

[0081] Example 1 Used disposable diapers were crushed, washed with water (rinsed), and dehydrated using the bag-breaking device shown in Figs. 1 and 2 to separate the plastic fraction.

[0082] The operating conditions of the bag-breaking device are as follows:

[0083] Rotating tub diameter: 180 cm Rotating tub depth: 120 cm Rotation speed: 30 rpm Crushing treatment time: 60 min Amount of used disposable diapers fed: 200 kg Chemicals fed: 12 kg of slaked lime, 0.4 kg of calcium hypochlorite Water fed: 800 L After crushing, the rotating tub was rotated at a high speed of 700 rpm for 5 minutes to dehydrate the material and discharge the wastewater, leaving a plastic fraction mainly composed of film, nonwoven fabric, and pulp in the rotating tub.

[0084] Next, 1000 L of tap water was supplied, and the rotating drum was rotated for 20 minutes in the same manner as above to rinse, and then dehydration was carried out in the same manner as above.

[0085] The properties of the plastic fraction after dehydration were as follows:

[0086] Moisture content: 57% Film ratio in solid content: 69% Pulp and polymer water-absorbing material ratio in solid content: 31% Film composition: PP, PE, PET Polymer water-absorbing material composition: polyacrylate Film longitudinal length: 15 to 450 mm Polymer water-absorbing material diameter: 1 to 2 mm Pulp fiber length: 2 to 5 mm

[0087] This plastic fraction was removed from the rotary tank 3 and subjected to the following treatment to reduce the pulp content.

[0088] Five kg of the plastic fraction was placed in a uniaxial crusher, Scissors Cutter Series PFS-40, manufactured by Nippon Seam Co., Ltd., and crushed. As a result, the plastic fraction was crushed to approximately 30 mm. This crushed material was placed in an air sorter, and separated into film, pulp, and polymer water absorbent material. The film fraction after separation was dried and the film content was measured, which was 90%. The recovered film was dried and the pulp content was measured. As a result, the pulp content of the film with a crushed diameter of 30 mm decreased from 31% to 10%. It was also confirmed that in a wet state, the difference in specific gravity between the plastic and pulp increases, improving the sorting efficiency.

[0089] Example 2 The plastic fraction obtained by the same procedure as in Example 1 before the pulp content reduction treatment was crushed to a crushing diameter of 30 mm or 50 mm using a uniaxial crusher, Scissors Cutter Series PFS-40, manufactured by Nippon Seam Co., Ltd. This crushed material (pulp content 30-40%) was subjected to gravity separation using a water-flow gravity separator. That is, the crushed material was placed on the water surface of the separator, and a water flow was generated by an agitator to separate the plastic film from the pulp. The floating plastic film was collected and dried, and the pulp content was measured, which was approximately 10%.

[0090] Comparative Example 1 A rotating drum-type bag-breaking device with a punched metal structure as shown in Figures 1 and 2 was used as a washing and separating machine. 200 kg of used disposable diapers collected from a care facility or the like, 12 kg of slaked lime, and 0.4 kg of sodium hypochlorite were placed in a drum (rotating tank), and 800 L of 80°C hot water was added. The drum was rotated for approximately 30 minutes to separate the used disposable diapers into their respective materials, and then rinsed in the same manner as in Example 1. The wastewater was discharged from the drum together with the pulp and polymeric water absorbent material.

[0091] The plastic fraction remaining in the drum was centrifuged and dehydrated in this washer / separator. The dehydrated product had a plastic film content of 70% and 30% pulp and polymeric water-absorbing material. The moisture content was 50%. The dehydrated product was then dried in the washer / separator by applying hot air.

[0092] The content of plastic film, pulp and polymeric water absorbent material in the dry residue remaining in the drum was measured, and it was found that the plastic film content was about 70%, and that the pulp and polymeric water absorbent material remained at about 30%.

[0093] [Test Example 1] The plastic fraction (water content: 57%) before the pulp content reduction treatment, obtained by the same procedure as in Example 1, was fed into a small uniaxial crusher HNSC20 manufactured by Helios Corporation at 10 to 20 kg / h and crushed, resulting in crushing into pieces of 5 cm or less.

[0094] [Test Example 2] The plastic fraction (moisture content: 57%) obtained by the same procedure as in Example 1 before the pulp content reduction treatment was fed into a small biaxial crusher HNSC60 series manufactured by Helios Corporation at a rate of 20 to 25 kg / h and crushed, resulting in crushing into pieces of 1 cm or less in size.

[0095] [Test Example 3] A plastic fraction with a moisture content of 30 to 40% before the pulp content reduction treatment, obtained by the same procedure as in Example 1, was fed into a uniaxial crusher, Scissors Cutter Series PF-2000, manufactured by Nippon Seam Co., Ltd., at a rate of 500 kg / h, and was crushed to crushed particles with diameters of 10 to 50 mm.

[0096] Test Example 4: A drying test was conducted using a ventilated box dryer with 3.5 kg of wet pulp (average length 3 mm, moisture content approximately 65%) and 0.5 kg of wet plastic film (PP, length 100-700 mm, width 10-50 mm, moisture content approximately 45%). The hot air temperature was set to 150°C, 130°C, or 110°C, and the pulp and plastic film were dried until their moisture contents were less than 10%.

[0097] As a result, the drying time for the pulp was less than 30 minutes when using hot air at 150°C and 130°C, and 40 minutes at 110°C. The drying time for the plastic film was less than 30 minutes under all temperature conditions. Regarding the state of the samples after drying, at 150°C and 130°C, brown discoloration was observed in the pulp and traces of melting were confirmed in the plastic film. At 110°C, no visible changes were observed in either the pulp or the plastic film.

[0098] [Test Example 5] A compression evaluation test was conducted using a compression volume reduction machine on the plastic fraction obtained by the same procedure as in Example 1 before the pulp content reduction treatment. The plastic fraction (pulp content 9-16%), which had been crushed to a diameter of 10-100 mm and had a moisture content of 50%, was compressed using the compression volume reduction machine, and the compression rate and state of the compressed product were confirmed. As a result, the volume was compressed to approximately one-tenth of its original size.

[0099] [Test Example 6] The plastic fraction was subjected to compression dehydration and granulation using a compression dehydrator. The plastic fraction, obtained by the same procedure as in Example 1 and having a moisture content of 50% and a pulp content of less than 20%, before the pulp content reduction treatment, was crushed to φ10 mm to φ50 mm. This crushed material was placed in a compression dehydrator, and compression dehydration and granulation were performed by adjusting the heater temperature within the range of 110 to 150°C to a temperature appropriate for the type of plastic in the plastic fraction. As a result, a compression-dehydrated granulated product with a moisture content of 3% or less was obtained, and its volume was reduced to one-third to one-quarter. It was also confirmed that diapers contain PET, but granulation was possible without any problems if the content was less than 10%.

[0100] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible within the scope of the invention. This application is based on Japanese Patent Application No. 2024-147728 filed on August 29, 2024, and is incorporated by reference in its entirety.

[0101] 2 Water tank 3 Rotating tank 6 Door body 5 Motor 9 Drain valve 11 Protrusion 12 Blade

Claims

1. A method for treating disposable diapers, comprising: a step of crushing and washing used disposable diapers; and a pulp content reduction step of reducing the pulp content of the pulp-containing plastic fraction produced in this step by crushing and sorting.

2. The method for treating disposable diapers according to claim 1, wherein the pulp content reduction step includes a sorting process subsequent to the shredding process.

3. The method for disposing of disposable diapers according to claim 2, wherein the sorting process is carried out by at least one of wind sorting, sieving, and wet specific gravity sorting.

4. The disposable diaper processing method of claim 3, wherein the sorting process is carried out by one selected from the group consisting of an air sorting process followed by a wet specific gravity sorting process, a sieving sorting process followed by a wet specific gravity sorting process, a sieving sorting process followed by an air sorting process, and a process in which the sieving sorting process, the air sorting process, and the wet specific gravity sorting process are carried out in this order.

5. The method for treating disposable diapers according to claim 4, wherein at least one of dehydration, drying and compression is carried out after the sorting process.

6. The method for treating disposable diapers according to claim 1, wherein the pulp content reduction step includes a crushing step subsequent to the sorting step.

7. The method for disposing of disposable diapers according to claim 6, wherein the sorting process is a sieving sorting process.

8. The method for disposing of disposable diapers according to claim 6, wherein a wind sorting process or a wet specific gravity sorting process is carried out after the shredding process.

9. The method for treating disposable diapers according to claim 8, wherein at least one of dehydration, drying and compression is carried out after the air sorting or wet specific gravity sorting.

10. A method for disposing of disposable diapers according to any one of claims 1 to 9, wherein the process of crushing and washing used disposable diapers is carried out using a bag-breaking device.

11. The bag-breaking device is a bag-breaking device using a drum-type washing machine having a water tank for storing wash water, a bottomed cylindrical rotating tub that is supported in the water tank so that it can rotate freely with its rotation axis approximately horizontal and that stores laundry, bag-breaking blades attached to the inner surface of the rotating tub, and a motor that rotates the rotating tub, and the method for treating disposable diapers of claim 10 comprises: feeding used disposable diapers, chemicals, and water into the bag-breaking device; rotating the rotating tub to crush the used disposable diapers; supplying cleaning water to wash the crushed material; and then increasing the rotation speed of the rotating tub to spin-dry the material.

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