A recycled molded article containing thermoplastic resin derived from used absorbent articles, and a method for producing the same.

Abstract

The present invention provides a recycled molded article containing thermoplastic resin derived from used absorbent articles, which enables effective recycling of thermoplastic resin while suppressing odor. [Solution] The recycled molded article contains a thermoplastic resin derived from used absorbent articles. The thermoplastic resin content in the recycled molded article is 60% by mass or more. The recycled molded article further contains a plant-derived processed material containing polyphenols.

Description

Technical Field

[0001] The present invention relates to a recycled molded body containing a thermoplastic resin derived from a used absorbent article, and a method for producing the same.

Background Art

[0002] Recycled molded bodies containing thermoplastic resins derived from used absorbent articles are known. For example, Patent Document 1 discloses a solid fuel (13) formed from waste. The solid fuel (13) contains pulp (6), plastic (8), and a polymer absorbent, and the used disposable diaper (1) after use as waste is decomposed with a decomposition treatment liquid (3) containing lime to recover the pulp (6), the plastic (8), and the polymer absorbent, and is formed using at least the plastic (8) recovered from the used disposable diaper (1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The solid fuel described in Patent Document 1 is formed from thermoplastic resin (plastic) from used absorbent articles (disposable diapers). However, according to the inventor's research, the following facts have been discovered for the first time: Recycled molded articles, such as solid fuel, formed using thermoplastic resin, emit an odor due to thermal degradation after formation. The source of this odor is aldehyde-based organic matter in the thermoplastic resin. This odor is not necessarily pleasant for humans. Therefore, the odor may limit the applications of the recycled molded articles. Reducing the content of thermoplastic resin derived from used absorbent articles could be considered to suppress the odor. However, this would reduce the amount of thermoplastic resin derived from used absorbent articles that can be reused. Therefore, this is not desirable from the viewpoint of effectively recycling the thermoplastic resin.

[0005] The object of the present invention is to provide a recycled molded article containing a thermoplastic resin derived from used absorbent articles, which can effectively recycle the thermoplastic resin while suppressing odor, and a method for producing the same. [Means for solving the problem]

[0006] One aspect of the present invention is a recycled molded article comprising a thermoplastic resin derived from used absorbent articles, wherein the thermoplastic resin content is 60% by mass or more, and further comprises a plant-derived processed product containing polyphenols.

[0007] Another aspect of the present invention is a method for producing a recycled molded article containing a thermoplastic resin derived from used absorbent articles, wherein the thermoplastic resin has a content of 60% by mass or more, and comprises an addition step of adding a plant-derived processed product containing polyphenols to the thermoplastic resin before molding the thermoplastic resin. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a recycled molded article containing a thermoplastic resin derived from used absorbent articles, which can effectively recycle the thermoplastic resin while suppressing odor, and a method for producing the same. [Modes for carrying out the invention]

[0009] This embodiment relates to the following aspects. [Aspect 1] A recycled molded article containing a thermoplastic resin derived from used absorbent articles, wherein the thermoplastic resin content is 60% by mass or more, and further contains a plant-derived processed material containing polyphenols.

[0010] In this recycled molded product, the content of thermoplastic resin derived from used absorbent articles is 60% by mass or more. This allows for the effective reuse of thermoplastic resin derived from used absorbent articles as a material for the recycled molded product. Furthermore, this recycled molded product also contains plant-derived processed materials containing polyphenols. Therefore, the hydroxyl groups (-OH) of polyphenols can encapsulate the aldehyde groups (-CH=O) of aldehyde-based organic substances, which are the source of odor in thermoplastic resins, thereby suppressing the odor caused by the aldehyde groups. In this way, this recycled molded product can effectively recycle thermoplastic resin while suppressing odor.

[0011] [Aspect 2] The recycled molded body according to embodiment 1, wherein the processed product includes tea leaves, and the size of the tea leaves is 5m or less.

[0012] In this recycled molded product, the plant-derived processed material containing polyphenols is tea leaves, thus supplying a larger amount of polyphenols. Furthermore, because the tea leaves are small (5 mm or less), their specific surface area can be increased. In addition, their small size allows for wider dispersion of the tea leaves within the recycled molded product. As a result, the polyphenols in the tea leaves can be more efficiently brought into contact with the thermoplastic resin. Therefore, this recycled molded product can suppress odors more effectively. If the tea leaves are too large (over 5 mm), it becomes difficult to mold the recycled product.

[0013] [Aspect 3] The recycled molded article according to embodiment 1 or 2, wherein the content of the processed material is 3 to 10% by mass.

[0014] In this recycled molded product, a deodorizing effect can be reliably obtained by ensuring that the content of plant-derived processed materials containing polyphenols is 3% by mass or more. On the other hand, the shape of the recycled molded product made of thermoplastic resin can be reliably maintained by ensuring that the content of plant-derived processed materials containing polyphenols is 10% by mass or less.

[0015] [Aspect 4] A recycled molded body according to any one of embodiments 1 to 3, wherein the bulk density is 0.2 to 0.5 and the higher heating value is 25 MJ / kg or more.

[0016] This recycled molded material has a bulk density of 0.2 to 0.5 and a higher heating value of 25 MJ / kg or more. In other words, this recycled molded material has excellent calorific value as a solid fuel. Therefore, this recycled molded material can be recycled more effectively as a high-quality solid fuel. In this process, the plant-derived processed material containing polyphenols, which contributes to odor suppression, can also contribute to combustion as a combustible material because it is plant-derived.

[0017] [Aspect 5] The recycled molded body according to aspect 4, wherein the moisture content is less than 5% by mass, the ash content is less than 5% by mass, and the chlorine atom content is less than 0.2% by mass.

[0018] In this recycled molded body, the gross calorific value, moisture content, ash content, and chlorine atom content conform to the standards of RPF-A in JIS Z7311:2010 "Solidified fuels (RPF) from waste such as paper and plastic". Therefore, this recycled molded body can be recycled more effectively as a high-quality solid fuel.

[0019] [Aspect 6] The recycled molded body according to any one of aspects 1 to 5, wherein Escherichia coli is below the detection limit.

[0020] In this recycled molded body, Escherichia coli derived from excrement, which causes problems in terms of hygiene during processing or reuse, is below the detection limit. That is, since the impurities derived from excrement are extremely few, this recycled molded body is superior in terms of hygiene and safety. Therefore, this recycled molded body can be effectively reused for various applications.

[0021] [Aspect 7] A method for producing a recycled molded body containing a thermoplastic resin derived from a used absorbent article, comprising an addition step of adding a processed product derived from a plant containing polyphenols to a mixture containing the thermoplastic resin before molding the mixture containing the thermoplastic resin, wherein the content of the thermoplastic resin in the recycled molded body is 60% by mass or more.

[0022] In the recycled molded articles produced by this method, the content of thermoplastic resin derived from used absorbent articles is 60% by mass or more. This allows for the effective reuse of thermoplastic resin derived from used absorbent articles as a material for recycled molded articles. Furthermore, this method includes an addition step in which a plant-derived processed material containing polyphenols is added to the mixture containing the thermoplastic resin before molding the mixture containing the thermoplastic resin. This makes it possible to produce recycled molded articles in which the aldehyde groups (-CH=O) of aldehyde-based organic substances, which are the source of the odor of thermoplastic resins, are encapsulated by the hydroxyl groups (-OH) of polyphenols. In other words, it is possible to produce recycled molded articles in which the odor caused by aldehyde groups is suppressed. Thus, this method can produce recycled molded articles that effectively recycle thermoplastic resins while suppressing odors.

[0023] [Aspect 8] The method according to embodiment 7, wherein the processed product includes tea leaves, and the size of the tea leaves is 5 mm or less.

[0024] In this method, since the plant-derived processed material containing polyphenols is tea leaves, a larger amount of polyphenols can be supplied. Furthermore, because the tea leaves are small (5 mm or less), when added to a mixture containing thermoplastic resin, they can be easily mixed with the thermoplastic resin and dispersed appropriately within the thermoplastic resin. This allows the polyphenols of the tea leaves to come into contact with the thermoplastic resin more efficiently. Therefore, this method can produce recycled molded articles with more suppressed odor.

[0025] [Aspect 9] The method according to embodiment 7 or 8, wherein the content of the processed material in the recycled molded body is 3 to 10% by mass.

[0026] In this method, a deodorizing effect can be reliably obtained if the content of plant-derived processed material containing polyphenols in the manufactured recycled molded article is 3% by mass or more. On the other hand, if the content of plant-derived processed material containing polyphenols is 10% by mass or less, a recycled molded article made of thermoplastic resin can be reliably formed.

[0027] [Aspect 10] The method according to any one of embodiments 7 to 9, further comprising a washing and dehydration step of washing and dehydrating the mixture containing the thermoplastic resin with an acid and / or an organic solvent before the addition step.

[0028] In this method, before the additive step, the mixture containing the thermoplastic resin is washed with acid and / or an organic solvent and dehydrated, thereby removing odor-generating organic substances other than aldehyde-based organic substances, as well as bacteria such as E. coli and other contaminants adhering to the mixture containing the thermoplastic resin. As a result, this method can effectively recycle the thermoplastic resin while more reliably suppressing odors, and can produce recycled molded articles with superior hygiene and safety.

[0029] The following describes a recycled molded article containing a thermoplastic resin derived from used absorbent articles according to this embodiment, and a method for manufacturing the same.

[0030] First, let's explain used absorbent articles. Used absorbent articles are absorbent articles that have been used and absorbed excrement (e.g., urine, feces, blood), absorbent articles that have been used but do not contain excrement, and absorbent articles that have been manufactured but not used (including production loss products). Examples of absorbent articles include disposable diapers, urine pads, incontinence pads, sanitary napkins, disposable underwear, bed linens, and pet linens.

[0031] Next, a typical example of the configuration of an absorbent article will be described. An absorbent article comprises a surface sheet, a back sheet, and an absorbent material placed between the surface sheet and the back sheet. The size of the absorbent article may be, for example, about 15 to 100 cm in length and 5 to 100 cm in width, but is not limited to this example. In addition, the absorbent article may further include other components that are generally present in absorbent articles, such as a diffusion sheet, a leak-proof wall, a side sheet, an outer sheet, and thread-like or sheet-like elastic members placed on the leak-proof wall or outer sheet.

[0032] Examples of components for the surface sheet include liquid-permeable nonwoven fabrics, synthetic resin films with liquid-permeable pores, and composite sheets thereof. Examples of components for the back sheet include liquid-impermeable nonwoven fabrics, liquid-impermeable synthetic resin films, and composite sheets thereof. Examples of components for the diffusion sheet include liquid-permeable nonwoven fabrics. Examples of components for the leak-proof wall and side sheets include water-repellent nonwoven fabrics. Examples of components for the outer sheet include liquid-impermeable and breathable nonwoven fabrics, liquid-impermeable and breathable synthetic resin films, and composite sheets thereof. Examples of components for the elastic member include rubber-based synthetic resins. There are no particular restrictions on the type of nonwoven fabric, and examples include meltblown nonwoven fabrics, spunbond nonwoven fabrics, airlaid nonwoven fabrics, and air-through nonwoven fabrics. There are no particular restrictions on the type of synthetic resin film, and known film materials can be used. There are no particular restrictions on the materials for nonwoven fabrics and synthetic resin films as long as they can be used for absorbent articles, but examples include olefin resins such as polyethylene and polypropylene, polyamide resins such as 6-nylon and 6,6-nylon, and polyester resins such as polyethylene terephthalate and polybutylene terephthalate. Cellulose fibers may also be used as the material for nonwoven fabrics. To provide breathability, the synthetic resin film may contain inorganic particles such as calcium carbonate. There are no particular restrictions on the materials for rubber-based synthetic resins as long as they can be used for absorbent articles, but examples include styrene-butadiene rubber and urethane rubber. These materials for nonwoven fabrics and synthetic resin films are synthetic resins and can be called plastic materials.

[0033] The components of the absorbent include absorbent materials, such as at least one of cellulose fibers and superabsorbent polymers. Examples of cellulose fibers include natural cellulose fibers such as wood pulp fibers, cross-linked pulp fibers, and non-wood pulp fibers, as well as regenerated cellulose fibers and semi-synthetic cellulose fibers. In the case of pulp fibers, the average major diameter of the fibers is, for example, several tens of μm, preferably 20 to 40 μm, and the average fiber length is, for example, several millimeters, preferably 2 to 5 mm. Examples of superabsorbent polymers (SAP) include polyacrylate-based, polysulfonate-based, and maleate anhydride-based superabsorbent polymers. Examples of the size of the superabsorbent polymer (when dry) include an average particle size of several hundred μm, preferably 200 to 500 μm. The absorbent may also include a core wrap formed of a liquid-permeable sheet.

[0034] One side and the other side of the absorbent are joined to the surface sheet and the back sheet, respectively, via adhesive. In a plan view, the portion of the surface sheet that extends outward from the absorbent, surrounding it (peripheral portion), is joined to the portion of the back sheet that extends outward from the absorbent, surrounding it (peripheral portion), via adhesive. Therefore, the absorbent is enclosed within the joint of the surface sheet and the back sheet. There are no particular restrictions on the adhesive, but examples include hot-melt adhesives. Examples of hot-melt adhesives include pressure-sensitive or heat-sensitive adhesives mainly composed of rubber such as styrene-ethylene-butadiene-styrene, styrene-butadiene-styrene, styrene-isoprene-styrene, polyurethane, or polyolefins such as polyethylene.

[0035] Next, a recycled molded article according to this embodiment will be described. This recycled molded article contains a thermoplastic resin derived from used absorbent articles and a plant-derived processed material. The thermoplastic resin content in the recycled molded article is 60% by mass or more. The plant-derived processed material contains polyphenols.

[0036] There are no particular restrictions on recycled molded products as long as they contain thermoplastic resin, but examples include solid fuels and containers.

[0037] The thermoplastic resin derived from used absorbent articles and included in the recycled molded article is not particularly limited as long as it is derived from materials commonly used as components of absorbent articles, for example, those derived from the plastic materials mentioned above. Examples of thermoplastic resins include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamide resins such as 6-nylon and 6,6-nylon, polyurethane resins such as urethane rubber, and styrene-containing polymers such as styrene-butadiene and styrene-ethylene-butadiene-styrene. The recycled molded article contains 60% by mass or more of such thermoplastic resin, preferably 70% by mass or more, and more preferably 80% by mass or more. This is mainly from the viewpoint of reuse in applications such as thermoplastic resin products and solid fuels.

[0038] The recycled molded body may further contain materials commonly used as components of absorbent articles, such as cellulose fibers, superabsorbent polymers, and inorganic materials. Examples of cellulose fibers include natural cellulose fibers, regenerated cellulose fibers such as rayon, refined cellulose fibers such as lyocell, and semi-synthetic cellulose fibers such as acetate fibers. Examples of natural cellulose fibers include pulp fibers such as wood pulp fibers and non-wood pulp fibers, and cotton fibers. Examples of superabsorbent polymers include polyacrylate-based, polysulfonate-based, maleate-based, polyacrylamide-based, polyvinyl alcohol-based, and polyethylene oxide-based polymers. Examples of inorganic materials include calcium carbonate, barium sulfate, zinc oxide, magnesium oxide, titanium dioxide, talc, silica, clay, kaolin, alumina, and mica.

[0039] Furthermore, whether or not the thermoplastic resin contained in the recycled molded product originates from used absorbent materials can be determined, for example, by whether or not it contains the aforementioned cellulose fibers and inorganic materials, which would not normally be found in non-recycled resins, particularly cellulose fibers.

[0040] Examples of polyphenols contained in plant-derived processed products include flavonoids with a diphenylpropane structure, simple phenols, hydrolyzable (pyrogallol-type) tannins, and condensed (catechol-type) tannins. Examples of flavonoids include flavanols (catechins), anthocyanidins, chalcones, flavones, isoflavones, flavanones, and flavonols. Among these, examples of flavanols (catechins) include epicatechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, catechin, catechin gallate, gallocatechin, and gallocatechin gallate. Examples of anthocyanidins include cyanidin and delphinidin. Examples of chalcones include xanthoangelol. Examples of flavones include apigenin and luteolin. Examples of isoflavones include genistein and daidzein. Examples of flavanones include hesperidin and naringenin. Examples of flavonols include quercetin and rutin. Examples of simple phenols include caffeic acid, chlorogenic acid, rosmarinic acid, gallic acid, and curcumin. Examples of hydrolyzable tannins include gelainin and eugenin. Examples of condensed tannins include procyanidin and theaflavin. Among these, flavanols (catechins) are preferred, mainly from the viewpoint of deodorizing recycled molded articles.

[0041] This recycled molded product contains 60% or more by mass of thermoplastic resin derived from used absorbent materials. This allows for the effective reuse of a large amount of thermoplastic resin derived from used absorbent materials. Potential reuse applications include, for example, materials for plastic products due to their excellent moldability and processability resulting from the high thermoplastic resin content, and materials for solid fuels due to their excellent flammability.

[0042] Furthermore, this recycled molded body contains plant-derived processed materials containing polyphenols. Therefore, the inclusion of thermoplastic resin derived from used absorbent materials in the recycled molded body can suppress the odor originating from used absorbent materials. This is thought to be because the hydroxyl groups (-OH) of polyphenols can encapsulate the aldehyde groups (-CH=O) of aldehyde-based organic substances, which are the source of the odor in thermoplastic resin derived from used absorbent materials, thereby suppressing the odor caused by the aldehyde groups. However, the reason for odor suppression is not limited to this mechanism.

[0043] Thus, this recycled molded product can effectively recycle thermoplastic resin while suppressing odor.

[0044] In a preferred embodiment of this product, the plant-derived processed material includes tea leaves. The tea leaves are not particularly limited as long as they contain polyphenols; for example, unfermented tea leaves such as green tea, semi-fermented tea leaves such as oolong tea, and fermented tea leaves such as black tea are suitable. Using tea leaves as the plant-derived processed material allows for a greater supply of polyphenols. Furthermore, green tea leaves containing a high amount of epigallocatechin gallate, a highly active component among flavanols, are preferred because they can more effectively deodorize.

[0045] There are no particular restrictions on the size of the tea leaves, as long as they are smaller than the size of the recycled molded body, but it is preferable that they be 5 mm or smaller. Smaller tea leaves (5 mm or smaller) allow for a larger specific surface area. Furthermore, their small size allows for wider dispersion of the tea leaves within the recycled molded body. As a result, the polyphenols in the tea leaves can be more efficiently brought into contact with the thermoplastic resin. Therefore, this recycled molded body can suppress odor more effectively. If the tea leaves are too large (over 5 mm), it becomes difficult to mold the recycled body.

[0046] In a preferred embodiment of this design, the content of plant-derived processed materials in the recycled molded article is 3 to 10% by mass. Thus, because the content of plant-derived processed materials containing polyphenols in the recycled molded article is 3% by mass or more, a deodorizing effect can be reliably obtained. On the other hand, because the content of plant-derived processed materials containing polyphenols is 10% by mass or less, the shape of the recycled molded article made of thermoplastic resin can be reliably maintained.

[0047] In a preferred embodiment of this design, the recycled molded body has a bulk density of 0.2 to 0.5 and a higher heating value of 25 MJ / kg or more. Because the recycled molded body possesses these characteristics, it is easy to handle as a solid fuel and has excellent heating properties. Therefore, this recycled molded body can be recycled more effectively as a high-quality solid fuel.

[0048] In a preferred embodiment of this design, the recycled molded body, having a higher heating value of 25 MJ / kg or more, has a moisture content of less than 5% by mass, an ash content of less than 5% by mass, and a chlorine atom content of less than 0.2% by mass. Because the recycled molded body possesses these characteristics, its higher heating value, moisture content, ash content, and chlorine atom content conform to the RPF-A standards in JIS Z7311:2010 "Solid Fuel (RPF) from Waste-Derived Paper, Plastics, etc.". Therefore, this recycled molded body can be recycled more effectively as a high-quality solid fuel.

[0049] E. coli levels are below the detection limit. Thus, in recycled molded products, E. coli derived from excrement, which poses hygiene problems during processing and reuse, is below the detection limit. In other words, because the amount of impurities derived from excrement is extremely low, recycled molded products are superior in terms of hygiene and safety. Therefore, these recycled molded products can be effectively reused for a variety of applications.

[0050] In a preferred embodiment of this model, the recycled molded article preferably contains a polyolefin resin as the main component of the thermoplastic resin. However, "main component" means that the proportion of the polyolefin resin in the thermoplastic resin is 50% by mass or more. In other words, the thermoplastic resin preferably contains 50% by mass or more of polyolefin resin. The thermoplastic resin more preferably contains 60% by mass or more of polyolefin resin, even more preferably 70% by mass or more, and even more preferably 80% by mass or more. Polyolefin resin refers to a polymer that contains olefins (e.g., ethylene, propylene, butylene, etc.), diolefins (e.g., butadiene, isoprene, etc.) as constituent elements. Examples of polyolefin resins include polyethylene and polypropylene. In a recycled molded article (thermoplastic resin), a higher proportion of polyolefin resin, which has a high heat output and a low melting point, results in superior moldability, processability, and flammability. There is no particular upper limit on the amount of polyolefin resin in the thermoplastic resin. However, if it is preferable to include other resins depending on the application of the recycled molded product, the upper limit may be, for example, 85% by mass.

[0051] Since recycled molded articles contain thermoplastic resin derived from used absorbent articles, if the used absorbent articles contained excrement, they may contain organic matter (sulfur compounds) present in the excrement that have sulfur atoms. However, in a preferred embodiment of this product, the proportion of sulfur atoms in the recycled molded article is suppressed to less than 0.1% by mass. In this way, the proportion of sulfur atoms derived from excrement, which poses hygiene problems when processed or reused, can be kept extremely low in recycled molded articles, thereby improving the hygiene and safety of the recycled molded article.

[0052] Thus, this recycled molded material is excellent in terms of moldability, processability, and flammability, as well as in terms of hygiene and safety, and is therefore suitable for material recycling and thermal recycling.

[0053] Next, a method for producing a recycled molded article containing a thermoplastic resin derived from used absorbent articles according to this embodiment will be described.

[0054] A method for producing recycled molded articles containing thermoplastic resin derived from used absorbent articles comprises an addition step of adding a plant-derived processed material containing polyphenols to a mixture containing the thermoplastic resin before molding the mixture. However, the content of the thermoplastic resin derived from used absorbent articles in the recycled molded article is 60% by mass or more. The mixture containing the thermoplastic resin will be described later.

[0055] In this method, the recycled molded article produced from a mixture containing thermoplastic resin derived from used absorbent articles has a thermoplastic resin content of 60% by mass or more. This allows for the effective reuse of thermoplastic resin derived from used absorbent articles. Furthermore, this method includes an addition step in which a plant-derived processed material containing polyphenols is added to the mixture containing the thermoplastic resin before molding. This makes it possible to produce a recycled molded article in which the aldehyde groups (-CH=O) of aldehyde-based organic substances, which are the source of the odor of thermoplastic resins, are encapsulated by the hydroxyl groups (-OH) of the polyphenols. In other words, it is possible to produce a recycled molded article in which the odor caused by aldehyde groups is suppressed. Thus, this method can produce a recycled molded article that effectively recycles thermoplastic resin while suppressing odor.

[0056] When the recycled molded body is used as solid fuel, the solid fuel is formed by extrusion molding using a mixture containing a thermoplastic resin to which, for example, a plant-derived processed product containing polyphenols is added after the above-mentioned additive step. The pressure and temperature, which are the conditions for extrusion molding, are not particularly limited as long as solid fuel can be formed. For example, the pressure can be 5 to 50 kg / cm². 2 Examples include the following, and the temperature can be, for example, 100 to 200°C. The solid fuel preferably has the characteristics of the recycled molded body described above. For example, the bulk density is preferably 0.2 to 0.5. If the bulk density is too low, the calorific value of the solid fuel may decrease too much, and if the bulk density is too high, the heat output may become too strong.

[0057] Solid fuel contains 60% by mass or more of thermoplastic resin, which has a high calorific value and is highly combustible. Furthermore, solid fuel contains plant-derived processed materials containing polyphenols that can suppress odors generated from used absorbent articles. Therefore, solid fuel has a high calorific value and combustibility, while suppressing odors from used absorbent articles. As a result, solid fuel is hygienic and highly stable.

[0058] On the other hand, if the recycled molded product is a container, such as a plastic bag, the plastic bag is formed by an inflation method or a die method using a mixture containing a thermoplastic resin to which a plant-derived processed product containing polyphenols has been added after the above-mentioned additive step. The conditions for the inflation method or the die method are not particularly limited as long as a plastic bag can be formed. For example, in the case of molded products such as trash cans, pallets, buckets, and portable toilets, these molded products are formed by extrusion molding using a mixture containing a thermoplastic resin to which a plant-derived processed product containing polyphenols has been added after the above-mentioned additive step. The pressure and temperature, which are the conditions for extrusion molding, are not particularly limited as long as a molded product can be formed.

[0059] This container contains 60% by mass or more of thermoplastic resin, which has high moldability and processability. Furthermore, this container contains a plant-derived processed material containing polyphenols that can suppress odors generated from used absorbent articles. Therefore, this container easily achieves the desired shape and suppresses odors from used absorbent articles. As a result, this container is hygienic and highly stable.

[0060] In a preferred embodiment of this product, the plant-derived processed product containing polyphenols in the manufacturing method includes tea leaves. The size of the tea leaves is 5 mm or less. Because the processed product is tea leaves, a larger amount of polyphenols can be supplied. Furthermore, because the size of the tea leaves is small (5 mm or less), when added to a mixture containing a thermoplastic resin, it can be easily mixed with the thermoplastic resin and dispersed appropriately within the thermoplastic resin. This allows the polyphenols of the tea leaves to come into contact with the thermoplastic resin more efficiently. Therefore, this method can produce recycled molded articles with more suppressed odor.

[0061] In a preferred embodiment of this design, the content of plant-derived processed material containing polyphenols added to the manufactured recycled molded article is 3 to 10% by mass. This ensures that a deodorizing effect is reliably obtained. On the other hand, if the content of plant-derived processed material containing polyphenols is 10% by mass or less, a recycled molded article made of thermoplastic resin can be reliably formed.

[0062] In a preferred embodiment of this product, a washing and dehydration step is further provided before the addition step, in which the mixture containing the thermoplastic resin is washed and dehydrated with acid and / or an organic solvent (the washing and dehydration step will be described later). This removes odor-generating organic substances other than aldehyde-based organic substances, as well as bacteria such as E. coli and dirt adhering to the mixture containing the thermoplastic resin. As a result, this method can more reliably suppress odors while effectively recycling the thermoplastic resin, and can produce recycled molded articles that are superior in terms of hygiene and safety.

[0063] Next, a first example of a method for producing a mixture containing a thermoplastic resin derived from used absorbent articles for recycled molded bodies according to this embodiment will be described.

[0064] This method comprises a first separation step S2, a second separation step S3, and a washing step S5. The plastic material produced by this method can be used as a mixture containing a thermoplastic resin derived from used absorbent articles for recycled molded bodies. In this embodiment, the method further comprises a crushing step S1, an air conveying step S4, and a compression dewatering and drying step S6. This reduces the amount of impurities in the produced plastic material. In this embodiment, the method further comprises a dust removal step S7, an SAP separation step S8, an oxidizing agent treatment step S9, a pulp fiber separation step S10, and a mixing step S11. This allows a mixture containing a thermoplastic resin to be formed by adding the pulp fibers and superabsorbent polymer separated in the SAP separation step S8 and the pulp fiber separation step S10 to the plastic material in the mixing step S11. Each step will be described below.

[0065] The crushing step S1 is a process in which used absorbent articles are crushed in a crushing device together with an inactivating aqueous solution containing an inactivating agent that inactivates superabsorbent polymers. In this embodiment, the crushing step S1 is carried out by a twin-shaft shredder, and the used absorbent articles are crushed in the inactivating aqueous solution to produce crushed material of, for example, a size of 1 to 150 mm. At that time, the superabsorbent polymers are inactivated and dehydrated in the inactivating aqueous solution, resulting in smaller particle sizes. The crushed plastic material, the inactivated superabsorbent polymer, and pulp fibers are sent together with the inactivating aqueous solution to the first separation step S2. Note that the crushed material and the inactivating aqueous solution may contain excrement (the same applies hereinafter).

[0066] As the inactivation aqueous solution, it is preferable to use an aqueous solution of an inorganic acid or an organic acid, i.e., an acidic aqueous solution. This makes it less likely for ash and chlorine to remain, and makes it easier to adjust the degree of inactivation (particle size and specific gravity) by pH. As the organic acid, citric acid, which has a chelating effect and a cleaning effect, is preferred, and as the inorganic acid, sulfuric acid, which does not contain chlorine and is low cost, is preferred. In this embodiment, sulfuric acid is used. The inactivation aqueous solution may also be an aqueous solution containing a polyvalent metal ion source capable of supplying known polyvalent metal ions. The pH of the acidic aqueous solution is preferably 1.0 to 4.0. A low pH allows for disinfection or sterilization.

[0067] Next, the first separation step S2 is a step in which the mixture of plastic material, inactivated superabsorbent polymer, pulp fibers, and inactivated aqueous solution supplied from the crushing step S1 is separated by a separation device into a first fraction containing plastic material and a second fraction containing inactivated superabsorbent polymer, pulp fibers, and inactivated aqueous solution. In this embodiment, the first separation step S2 is carried out by a pulper separator. In this case, the second fraction containing inactivated superabsorbent polymer, pulp fibers, and acidic aqueous solution is accepted and sent to the dust removal step S3. On the other hand, the first fraction, such as film and nonwoven fabric, is rejected and sent to the second separation step S4. The film and nonwoven fabric separated as the first fraction can be called plastic material. Note that in the first separation step S2, some of the pulp fibers and superabsorbent polymer may not pass through the screen and remain on the screen together with the first fraction. On the other hand, some of the film and nonwoven fabric may pass through the screen together with the second fraction.

[0068] Next, the second separation step S3 is a step in which the first fraction is separated into plastic material and pulp fibers and superabsorbent polymer that were not completely separated in the first separation step S2 by applying physical impact. In other words, in the second separation step S3, the plastic material and the remaining pulp fibers and superabsorbent polymer are separated from the mixture of the plastic material and the remaining pulp fibers and superabsorbent polymer. As a result, the plastic material is recovered.

[0069] In this embodiment, the second separation step S3 separates the first fraction by treating it with water or an acidic aqueous solution (hereinafter also simply referred to as "water, etc.") while applying physical shock to the first fraction. Specifically, the mixture (plastic material and residue) from which the pulp fibers, superabsorbent polymer, and acidic aqueous solution were separated in the first separation step S2 is first supplied to the separation device. The separation device comprises a cylindrical section installed on its side, a plurality of impellers arranged around a rotation axis inside the cylindrical section, a plurality of liquid supply sections provided on the upper outer circumferential surface of the horizontally positioned cylindrical section, and a screen provided on the lower outer circumferential surface of the cylindrical section. There is a mixture supply port on one end of the cylindrical section and an outlet on the other end. The plurality of impellers are arranged at intervals along the central axis of the cylindrical section such that their rotation axes overlap with the central axis of the cylindrical section. The orientation of the blades of the plurality of impellers is adjusted so that they rotate around the central axis of the cylindrical section and create an airflow from one end to the other of the cylindrical section. Multiple liquid supply units are arranged at intervals along the central axis and spray fresh water or other liquid downwards towards the cylindrical section. Preferably, the liquid supply units spray the water or other liquid in a spray-like manner. The size of the individual openings in the screen is such that pulp fibers and superabsorbent polymers can pass through, but plastic materials cannot.

[0070] The mixture is agitated by rotating impeller blades in the air within the cylindrical section of the separation device, with water or other liquids being injected from each of several liquid supply ports. The mixture moves (flows) from one end of the cylinder to the other, while being subjected to physical impacts from the collisions of the impeller blades. During this time, the mixture is washed clean by the injected water, and pulp fibers and superabsorbent polymers in the mixture are removed from the plastic material in the mixture by the physical impact of the water. The removed pulp fibers and superabsorbent polymers pass through a screen at the bottom of the cylinder and are separated (removed) along with the water. Meanwhile, the plastic material, with the pulp fibers and superabsorbent polymers removed, does not pass through the screen and is discharged from the outlet at the other end of the cylinder for recovery.

[0071] The recovered plastic material may be used as a thermoplastic resin derived from used absorbent articles, or it may proceed to the following air transport process S4 and subsequent steps.

[0072] The air transport process S4 is a process in which the plastic material separated in the second separation process S3 is transported by air to the washing process S5. In other words, in the air transport process S4, the separated plastic material is dried in the airflow while being transported to the next washing process S5. At this time, the moisture content of the plastic material decreases. The moisture content decreases, for example, from about 95% to about 80%. Multiple plastic materials can be separated into individual parts by the airflow.

[0073] The cleaning step S5 is a step in which a cleaning solution is sprayed onto the plastic material separated in the second separation step S3. In this step, sulfur compounds and nitrogen compounds derived from excrement that were not completely removed in the second separation step S3 and remain on the plastic material are removed by the cleaning solution. Furthermore, other impurities such as pulp fibers and superabsorbent polymers that may remain in trace amounts can also be removed by the cleaning solution. In addition, if the cleaning solution has a bactericidal effect, the plastic material may be sterilized by it. If the cleaning solution is an oxidizing agent, sulfur compounds and nitrogen compounds are oxidized and converted into other odorless substances (e.g., sulfur (S) and nitrogen (N2)), which mix into the cleaning solution and / or are released as gas.

[0074] Here, the cleaning solution may be, for example, an aqueous solution containing an oxidizing agent, or water. The oxidizing agent may contain at least one of ozone and hydrogen peroxide. As for the water, depending on the amount of impurities in the plastic material, examples include water at room temperature and pressure, high-temperature and / or high-pressure water or steam, or superheated steam. A disinfectant may also be included. In this embodiment, an aqueous solution of an oxidizing agent is used, and ozone is used as the oxidizing agent from the viewpoint of oxidizing power, disinfecting power, and bleaching power. Specifically, as the aqueous solution of the oxidizing agent, ozonated water (for example, ozone concentration: 0.2 to 10 ppm, CT value: 0.5 to 200 ppm·min) is used, which is obtained by mixing ozone gas with water (or aqueous solution) such as pure water or tap water. By performing the cleaning process S5 using the aqueous solution of the oxidizing agent, general bacteria in the plastic material can be removed to below the detection limit, similar to E. coli, and sulfur compounds and nitrogen compounds can be decomposed, reducing the odor of excrement to a level that is almost imperceptible. Examples of ozone generators include the ED-OWX-2 ozone water exposure tester manufactured by Eco Design Co., Ltd., the OS-25V ozone generator manufactured by Mitsubishi Electric Corporation, and the REX MC ozonizer MC-985S manufactured by a subsidiary of REX Industries Co., Ltd.

[0075] In this embodiment, an aqueous solution of an oxidizing agent is sprayed onto the plastic material as a cleaning solution to remove sulfur compounds and nitrogen compounds derived from excrement remaining on the plastic material. However, this embodiment is not limited to this. For example, a heated liquid (e.g., high-temperature water or steam, superheated steam) may be sprayed onto the plastic material as a cleaning solution to remove impurities such as sulfur compounds and nitrogen compounds derived from excrement, general bacteria, and E. coli remaining on the plastic material. Alternatively, a heated gas (e.g., high-temperature and / or high-pressure air) may be sprayed onto the plastic material as a cleaning gas instead of a cleaning solution. In this case, examples of the apparatus and spraying method include using a cleaning gas instead of a cleaning solution in the apparatus of cleaning step S5, or exposing the plastic material to an atmosphere of cleaning gas.

[0076] In these cases as well, impurities such as sulfur compounds, nitrogen compounds, general bacteria, and E. coli in the plastic material can be decomposed and / or peeled off to remove them from the plastic material. In these cases, since no oxidizing agent aqueous solution is used, it is safe and hygienic, and treatment costs can be reduced because there is no need to treat wastewater such as oxidizing agent aqueous solution. Alternatively, for example, depending on the amount of impurities in the plastic material, it may not be necessary to perform a treatment such as the washing step S5 described above. In that case, for example, simply rinsing with water, or doing nothing at all, may be used to remove impurities such as sulfur compounds, nitrogen compounds, general bacteria, and E. coli remaining in the plastic material from excrement by heating and pressurizing in the pressing dewatering and drying step S6 described later.

[0077] The compression, dehydration, and drying process S6 is a process in which the plastic material processed in the washing process S5 is compressed, dehydrated, and dried. In other words, in the compression, dehydration, and drying process S6, multiple processed plastic materials are bundled together and compressed as a whole to dehydrate them while being heated and dried.

[0078] For example, the heating temperature can range from 80 to 160°C. Higher temperatures may cause pulp fibers in the plastic material to carbonize, while lower temperatures make drying difficult. For example, the heating time can range from 5 seconds to 5 minutes. Longer times result in saturated drying, while shorter times make drying difficult. For example, the compression pressure can range from 0.2 to 4 MPa. Lower pressure makes dewatering difficult, while higher pressure results in saturated dewatering. The compression dewatering and drying apparatus softens the plastic material and extrudes it through numerous holes (e.g., opening diameter: 5 to 15 mm). This allows the plastic material to be molded into flake or pellet shapes, making it easier to package.

[0079] This compression dehydration and drying process S6 also allows for the decomposition and / or removal of impurities such as sulfur compounds, nitrogen compounds, general bacteria, and E. coli from the plastic material. Since this process does not involve additional steps such as wastewater treatment with an oxidizing agent solution, it is safe and hygienic and reduces processing costs. At this time, the moisture content of the plastic material is 5% by mass or less, preferably 3% or less.

[0080] In this way, a mixture containing plastic materials, i.e., thermoplastic resins derived from used absorbent articles for recycled molded products, is produced. In addition to the thermoplastic resins derived from used absorbent articles, this mixture containing thermoplastic resins may also contain, to a small extent, materials commonly found in absorbent articles, such as cellulose fibers, superabsorbent polymers, and inorganic materials.

[0081] The mixture containing the pulp fibers, superabsorbent polymer, and acidic aqueous solution separated in the first separation step S2 is then treated as appropriate in a dust removal step, a superabsorbent polymer separation step, an oxidizing agent treatment step, and a pulp fiber separation step to separate the pulp fibers and superabsorbent polymer, respectively. The separated pulp fibers and superabsorbent polymer are then reused.

[0082] Next, a second example of a method for producing a mixture containing a thermoplastic resin derived from used absorbent articles for recycled molded bodies according to this embodiment will be described.

[0083] This method comprises a washing step S13 and a first separation step S15. The plastic material produced by this method can be used as a mixture containing thermoplastic resin derived from used absorbent articles for recycled molded bodies. In this embodiment, the method may further comprise a bag breaking step S11, a pretreatment step S12, and a first oxidizing agent treatment step S14. This can further reduce impurities in the produced plastic material. Each step will be described below.

[0084] This method produces recycled plastic material derived from used absorbent articles from a material mixture containing the plastic material of used absorbent articles. The material mixture is not particularly limited as long as it contains the plastic material of used absorbent articles. Examples of the material mixture include used absorbent articles (themselves) and assemblies of multiple components derived from used absorbent articles. Examples of such assemblies include collections of plastic material and other materials (e.g., superabsorbent polymers and pulp fibers) extracted from used absorbent articles. Examples of such assemblies include those with a higher proportion of plastic material and a lower proportion of other materials (e.g., superabsorbent polymers and pulp fibers) compared to absorbent articles (products).

[0085] (1) Bag breaking process S11 The bag-breaking step S11 is a step in which, if the material mixture is contained in a packaging bag, the packaging bag containing the material mixture is broken open before the washing step S13. The broken packaging bag is removed, and the material mixture is taken out of the packaging bag. At this time, it is preferable not to crush or damage the material mixture as much as possible. This is to make it easier to reuse the materials and components by not damaging the materials and components in the material mixture. If the material mixture is not contained in a packaging bag or if it is otherwise unnecessary, the bag-breaking step S11 can be omitted. An example of a device that performs the bag-breaking step S11 is a bag-breaking device that breaks open packaging bags containing recyclable waste (e.g., PET bottles, cans, glass bottles, plastic containers and packaging) without damaging the recyclable waste.

[0086] (2) Pretreatment step S12 The pretreatment step S12 is a step to reduce the moisture content of the material mixture before the washing step S13. If the amount of moisture (e.g., urine) in the material mixture is large, the amount of water will increase in the steps after the washing step S13, which may make it difficult to control the composition of the processing solution. Therefore, in this method, the moisture content of the material mixture is reduced by the pretreatment step S12 before the washing step S13. The moisture content of the material mixture after the pretreatment step S12 can be, for example, 30 to 80% by mass. Note that the pretreatment step S12 can be omitted if it is not necessary, such as when the moisture content of the material mixture is low. There are no particular restrictions on the apparatus (method) for performing the pretreatment step S12 as long as the above moisture content of the material mixture can be achieved, but for example, a drying apparatus for drying the material mixture can be used. For example, drying conditions in the drying apparatus can be a temperature of 60 to 110°C and a time of 2 to 48 hours.

[0087] (3) Washing process S13 The washing step S13 is a step of washing the plastic material by stirring a mixture of a material mixture containing the plastic material of used absorbent articles and a treatment liquid containing at least one of a non-flammable hydrophobic organic solvent, a hydrophilic organic solvent, and water. The material mixture may also be an aggregate containing used absorbent articles or plastic material that has not undergone the bag breaking step S11 and / or the pretreatment step S12.

[0088] The treatment solution contains at least one of a non-flammable hydrophobic organic solvent, a hydrophilic organic solvent, and water. Therefore, the treatment solution may contain a non-flammable hydrophobic organic solvent, a hydrophilic organic solvent, and water; it may contain a non-flammable hydrophobic organic solvent and a hydrophilic organic solvent (without water); or it may contain a non-flammable hydrophobic organic solvent and water (without the hydrophilic organic solvent). Other solvents, chemicals, aqueous solutions, etc., may be included as long as they do not affect the cleaning effect. The total proportion of at least one of the non-flammable hydrophobic organic solvent, hydrophilic organic solvent, and water in the treatment solution is, for example, 50% by mass or more. From the viewpoint of cleaning effectiveness, a higher proportion is preferable, therefore, 70% by mass or more is preferable, 80% by mass or more is more preferable, and 90% by mass or more is even more preferable.

[0089] In the context of non-flammable hydrophobic organic solvents, "hydrophobic organic solvent" refers to an organic solvent that is miscible with water. As long as the non-flammable hydrophobic organic solvent is a liquid and capable of cleaning plastic materials contained in a material mixture, there are no particular restrictions. Non-flammable hydrophobic organic solvents are thought to remove contaminants (mainly lipophilic substances) from plastic materials by dissolving them in the solvent itself. However, this mechanism is not the only possible mechanism.

[0090] Examples of non-flammable hydrophobic organic solvents include fluorinated organic solvents, aromatic organic solvents, and combinations of at least two of these. Examples of fluorinated organic solvents include hydrochlorofluoroolefin solvents, such as 1-chloro-2,3,3-trifluoropropene. Alternatively, examples of hydrofluoroolefin solvents include 1,1,1,3,3-pentafluorobutane and 1,3,3,3-tetrafluoropropene. Such non-flammable hydrophobic organic solvents can more reliably disperse plastic materials in the treatment liquid, making them loose, and can more reliably remove lipophilic contaminants. Furthermore, fluorinated organic solvents, especially 1-chloro-2,3,3-trifluoropropene, 1,1,1,3,3-pentafluorobutane, and 1,3,3,3-tetrafluoropropene, have low volatility and flammability, making them easy to handle from a safety standpoint. Examples of the above-mentioned aromatic organic solvents include aromatic hydrocarbons, such as benzene-based aromatic hydrocarbons, such as toluene and xylene.

[0091] A hydrophilic solvent is a liquid that is miscible with water. A hydrophilic organic solvent is a liquid, and there are no particular restrictions as long as it can clean the plastic material contained in the material mixture. For example, a hydrophilic organic solvent is thought to remove contaminants (mainly hydrophilic) from the plastic material by dissolving them in itself. However, this mechanism is not the only one that works.

[0092] Examples of hydrophilic organic solvents include ketone-based organic solvents, alcohol-based organic solvents, and combinations of at least two of these. Examples of ketone-based organic solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, and cyclohexanone. Examples of alcohol-based organic solvents include methanol, ethanol, propanol, butanol, and pentanol. Such hydrophilic organic solvents can more reliably remove hydrophilic contaminants. Furthermore, ketone-based organic solvents, particularly acetone, dissolve water well, are difficult to oxidize with oxidizing agents, and have the property of protecting functional groups. Therefore, acetone, especially when oxidizing agent treatment is performed simultaneously, can remove some or all of the contaminants contained in the material while suppressing the decomposition (dissolution) of easily decomposable plastic materials. In addition, by combining it with a non-flammable hydrophobic organic solvent and reducing the amount of hydrophilic organic solvent used, the safety of the treatment solution can be improved in terms of volatility and flammability.

[0093] Furthermore, non-flammable hydrophobic organic solvents and hydrophilic organic solvents, particularly non-flammable hydrophobic organic solvents, can dissolve adhesives that join together components of used absorbent articles (for example, at least two of plastic materials, superabsorbent polymers, and pulp fibers). This makes it easier to separate the components of used absorbent articles from each other. Therefore, if the material mixture is used absorbent articles (the articles themselves), it makes it easier to decompose the used absorbent articles into their individual components.

[0094] The proportion of the non-flammable hydrophobic organic solvent in the treatment solution can be, for example, 20% by mass as a lower limit, and preferably 30% by mass. For example, the upper limit can be 95% by mass, and preferably 85% by mass. A proportion of 20% by mass or more makes it easier to remove lipophilic contaminants and adhesives, and when used in combination with a hydrophilic organic solvent, it enhances the safety of the treatment solution in terms of volatility and flammability. A proportion of 95% by mass or less allows for use in combination with hydrophilic organic solvents or water, making it easier to remove hydrophilic contaminants.

[0095] On the other hand, the lower limit of the ratio of at least one of the hydrophilic organic solvent and water in the treatment solution is, for example, 5% by mass, and preferably 10% by mass. The upper limit is, for example, 80% by mass, and preferably 70% by mass. If the ratio is 5% by mass or more, hydrophilic contaminants can be easily removed. If the ratio is 90% by mass or less, it can be used in combination with a non-flammable hydrophobic organic solvent, which enhances the safety of the treatment solution in terms of volatility and flammability, and also makes it easier to remove lipophilic contaminants. The mass ratio of the hydrophilic organic solvent to water in the treatment solution is 0:100 to 100:0, although this also depends on the mass ratio of the non-flammable hydrophobic organic solvent to the hydrophilic organic solvent and water.

[0096] The treatment solution is mainly composed of a hydrophobic agent (non-flammable hydrophobic organic solvent) and a hydrophilic agent (hydrophilic organic solvent, water), and the hydrophobic agent and the hydrophilic agent tend to separate from each other. Therefore, in this method, in the washing step S13, the plastic material is washed while stirring the mixed solution, which is a mixture of the material mixture and the treatment solution, thereby suppressing the separation of the treatment solution during washing.

[0097] The preferred state of agitation is one in which the hydrophobic agent and the hydrophilic agent are dispersed almost uniformly, i.e., an emulsified state. If the treatment tank containing the treatment liquid is rotating, the agitation conditions can be, for example, 20 to 200 rpm, with 40 to 100 rpm being preferred. If agitation is performed within the treatment tank using an agitator blade, for example, 100 to 2000 rpm can be used, with 200 to 1000 rpm being preferred.

[0098] The proportion of the material mixture (including plastic material) in the mixed liquid is not particularly limited, as long as the washing process S13 can be carried out. For example, the proportion can be 0.1 to 20% by mass, and 1 to 10% by mass is preferred. A proportion of 0.1% by mass or more allows for efficient processing. A proportion of 20% by mass or less facilitates dewatering and washing.

[0099] In the washing step S13, there are no particular restrictions on the washing temperature as long as the washing process can be performed, but it should be at least lower than the boiling point of any of the non-flammable hydrophobic organic solvents, hydrophilic organic solvents, or water. Examples of washing temperatures include room temperature (example: 25°C) to 50°C, with 30 to 40°C being preferred. A temperature above room temperature makes it easier to shorten the time required for dehydration and washing. A temperature below 50°C makes it easier to suppress the evaporation (boiling) of organic solvents. There are no particular restrictions on the washing time as long as the washing process can be performed, but examples include 1 to 200 minutes.

[0100] The apparatus for performing the washing process S13 is not particularly limited in its specific configuration, as long as it can store a processing liquid, immerse the material mixture in the processing liquid, and agitate the processing liquid containing the material mixture. Examples of such apparatus include one having a tank in which the material mixture can be placed and the processing liquid can be stored, a supply means for supplying the processing liquid into the tank, and an agitation means for agitating the processing liquid in the tank.

[0101] (4) First oxidizing agent treatment step S14 The first oxidizing agent treatment step S14 is a step in which the material mixture in the mixed liquid is treated with an oxidizing agent while stirring the mixed liquid, before the first separation step S15. The first oxidizing agent treatment step S14 may be performed simultaneously with the washing step S13 or after the washing step S13. The first oxidizing agent treatment step S14 bleaches, sterilizes or disinfects, and deodorizes the material mixture in the mixed liquid with an oxidizing agent.

[0102] If the first oxidizing agent treatment step S14 is performed simultaneously with the washing step S13, the oxidizing agent is added to the treatment solution before or during the washing of the material mixture. The material mixture is then treated with the oxidizing agent while being washed with the treatment solution. If the first oxidizing agent treatment step S14 is performed after the washing step S13, the oxidizing agent is added to the treatment solution after the material mixture has been washed with the treatment solution. The material mixture is then treated with the oxidizing agent after being washed with the treatment solution.

[0103] The oxidizing agent is not particularly limited as long as it can remove contaminants contained in the material mixture while minimizing the impact on each component (e.g., damage to the components). The oxidizing agent may be, for example, a liquid or a gas mixed with a liquid, and is thought to reduce the contaminants by oxidizing and decomposing them, reducing their molecular weight, and making them more soluble in the solution, but is not limited to this mechanism.

[0104] Examples of oxidizing agents include ozone, hydrogen peroxide, and chlorine-based substances (e.g., sodium hypochlorite), or combinations of two or more of these. Because these oxidizing agents have relatively high oxidizing power, they are effective in reducing contaminants contained in various components of used absorbent articles, such as plastic materials. This allows for the removal of bacteria and the reduction of odor and coloring substances, enabling more reliable sterilization, disinfection, deodorization, and decolorization of each component. Note that when using acetone as the hydrophilic organic solvent, hydrogen peroxide should not be used as the oxidizing agent.

[0105] The oxidizing agent may be mixed into the treatment solution, or it may be mixed with another solvent (e.g., an organic solvent, acidic water, or water) before being mixed into the treatment solution.

[0106] When using gaseous ozone as an oxidizing agent and supplying gaseous ozone to the treatment solution to form a treatment solution containing the oxidizing agent, the ozone concentration in the treatment solution is not particularly limited, as long as it is a concentration that can reduce the fouling substances contained in each component. For example, the ozone concentration can be 0.2 to 2 ppm by mass. A concentration of 0.2 ppm by mass or higher facilitates the reduction of fouling substances, and a concentration of 2 ppm by mass or lower can suppress damage to each component. The contact time between the ozone-containing treatment solution and each component is not particularly limited, as long as it is a time that can reduce the fouling substances contained in each component. Generally, the contact time should be shorter when the ozone concentration is high and longer when the ozone concentration is low. For example, the contact time can be 1 to 200 minutes. The product of ozone concentration (ppm by mass) and contact time (minutes) (hereinafter also referred to as the "CT value") can be 0.2 to 40 ppm by mass·minute. A CT value of 0.2 ppm·min or higher facilitates the reduction of contaminants, while a CT value of 40 ppm·min or lower suppresses oxidative decomposition of each component, especially easily decomposed components. Ozone treatment reduces contaminants contained in each component, for example, by removing bacteria, odor-causing substances, and color-causing substances, and can sterilize, disinfect, deodorize, and decolorize (bleach) each component. The ozone generator is as described above.

[0107] When using a gas (e.g., ozone) as an oxidizing agent, the oxidizing agent may be supplied to the treatment liquid by, for example, the following method. This method involves generating a predetermined amount of oxidizing agent in an oxidizing agent generator, continuously supplying the oxidizing agent to the treatment liquid in the treatment tank at a predetermined airflow rate, while continuously disposing of (discharging) the same amount of waste oxidizing agent (used oxidizing agent) outside the treatment tank. In this case, a flow of oxidizing agent is easily generated, new oxidizing agent is easily continuously supplied to the surface of each component, and reactants are easily continuously discharged from that surface. Therefore, the oxidation reaction on the surface of each component can be carried out more reliably.

[0108] The proportion of the material mixture in the above-mentioned treatment solution is not particularly limited, as long as the above-mentioned oxidizing agent treatment can be carried out. For example, the proportion can be 0.1 to 20% by mass, and 1 to 10% by mass is preferred. A proportion of 0.1% by mass or more allows the treatment to proceed efficiently. A proportion of 20% by mass or less facilitates the oxidizing agent treatment.

[0109] Dirt, such as excrement, sebum, bacteria, odor-causing substances, and coloring agents derived from them, machine oil from manufacturing equipment, and various organic substances, is expected to be reduced as follows: Dehydration primarily releases dirt absorbed inside each component along with water to the outside. At the same time, dirt attached to each component is also released to the outside along with the released water. Simultaneously, oxidation primarily decomposes dirt attached to each component (including that released from the inside and attached), reducing its molecular weight, solubilizing it, and removing it. This also makes sterilization, disinfection, deodorization, and bleaching of each component possible. However, the reduction of dirt on each component is not limited to this mechanism.

[0110] In the first oxidizing agent treatment step S14, there are no particular restrictions on the temperature of the oxidizing agent treatment as long as the above-described oxidizing agent treatment can be performed, but it should be at least lower than the boiling point of the treatment solution. Examples of oxidizing agent treatment temperatures include room temperature (example: 25°C) to 50°C, with 30 to 40°C being preferred. A temperature above room temperature makes it easier to shorten the time required for the oxidizing agent treatment. A temperature below 50°C makes it easier to suppress the evaporation (boiling) of the organic solvent.

[0111] This method includes a first oxidizing agent treatment step S14, which is performed before the first separation step S15 (or simultaneously with the washing step S13), in which the material mixture (including plastic material) in the mixed liquid is treated with an oxidizing agent while the mixed liquid is being stirred. This first oxidizing agent treatment step S14 can bleach, sterilize or disinfect, and deodorize the material mixture. As a result, the material mixture can be made more hygienic. At this time, since the oxidizing agent treatment is performed in the presence of at least a non-flammable hydrophobic organic solvent among a non-flammable hydrophobic organic solvent and a hydrophilic organic solvent, damage to the plastic material by the oxidizing agent can be suppressed. Thus, in the first oxidizing agent treatment step S14, bleaching, sterilization or disinfection and deodorization are performed in a highly safe environment while suppressing damage, so a more hygienic plastic material can be obtained.

[0112] Furthermore, the first oxidizing agent treatment step S14 may be omitted if it is not necessary, such as when the material mixture is sufficiently hygienic due to the washing step S13 or the like.

[0113] (5) First separation step S15 The first separation step S15 is a step in which the plastic material is separated from the other components (superabsorbent polymer and pulp fiber) from the mixed liquid. However, the mixed liquid may be the liquid immediately after the washing step S13 (omitting the first oxidizing agent treatment step S14), or it may be the liquid after both the washing step S13 and the first oxidizing agent treatment step S14. The separated plastic material is taken out from the mixed liquid containing contaminants and other components, so it can be said to be a recycled material that has been dewatered and washed, and the amount of contaminants and other components has been reduced.

[0114] In the first separation step S15, for example, the plastic material is separated from the mixture of the material mixture containing the plastic material and other components and the processing liquid. The separated material can be recycled plastic material.

[0115] The apparatus for performing the first separation step S15 is not particularly limited in its specific configuration, as long as it is capable of separating the plastic material from the mixed liquid. Examples of separation methods include using one screen or a combination of multiple screens, using specific gravity, using centrifugal force, or a combination thereof.

[0116] In this way, a mixture containing plastic materials, i.e., thermoplastic resins derived from used absorbent articles for recycled molded products, is produced. In addition to the thermoplastic resins derived from used absorbent articles, this mixture containing thermoplastic resins may also contain, to a small extent, materials commonly found in absorbent articles, such as cellulose fibers, superabsorbent polymers, and inorganic materials.

[0117] <Method for measuring components> The components in a mixture containing thermoplastic resin (an example of a raw material for recycled molded products) or solid fuel (an example of a recycled molded product) are measured using the following method. The measurement method involves separating the components by utilizing the differences in their solubility in various solvents. (1) The sample of the thermoplastic resin to be measured, either a mixture or solid fuel, is dissolved and dispersed in tetrahydrofuran (THF), and then filtered and separated (5 μm filter) to separate the solvent-soluble component from the solvent-insoluble component. The solvent-soluble component of THF is centrifuged (12,000 rpm × 0.5 h) to separate the solvent-insoluble component (F11) from the solvent-soluble component. The solvent-soluble component after centrifugation is dissolved and dispersed in methanol, and then filtered and separated (3 μm filter) to separate the solvent-insoluble component (F12) from the solvent-soluble component (F13). The solvent-insoluble components of THF are dissolved and dispersed with hexafluoroisopropanol (HFIP), and then separated by filtration (5 μm filter) to separate them into solvent-soluble and solvent-insoluble components. The solvent-soluble components of HFIP are dissolved and dispersed with methanol, and then separated by filtration (3 μm filter) to separate them into solvent-insoluble components (F21) and solvent-soluble components (F22). The solvent-insoluble components of HFIP are dissolved and dispersed with heated xylene, and then separated by filtration (200 mesh) to separate them into solvent-soluble components and solvent-insoluble components (F31). The solvent-soluble components of xylene are dissolved and dispersed with methanol, and then separated by filtration (3 μm filter) to separate them into solvent-insoluble components (F32) and solvent-soluble components (F33). (2) Next, IR analysis is performed on each of the separated fractions (F11-F13, F21-F22, F31-F33, F41-F43). (3) Regarding the mixture of fraction F12 and fraction F13, 1 Perform 1H NMR. (4) Regarding fraction F32, high temperature 13 Perform 13C NMR. (5) Fraction F31 is carbonized in an electric furnace (570°C, 2 hours), the residue is used as ash, and the loss is used as pulp fiber. (6) Based on the results of (2) to (5) above, determine the ratio of components in the mixture containing thermoplastic resin or solid fuel and the qualitative results.

[0118] <Method for measuring the content of sulfur, nitrogen, aluminum, chlorine, and lead> The method for measuring the sulfur, nitrogen, aluminum, and chlorine content (mass%) of a mixture containing thermoplastic resin or a solid fuel is as follows. (1) Prepare an energy-dispersive X-ray analyzer (EDX: Shimadzu EDX-7200). (2) Dry the mixture or solid fuel containing the thermoplastic resin to be measured (120°C for 60 minutes), take a sample from the dried mixture or solid fuel containing the thermoplastic resin that is large enough to be placed on the sample stage of the analyzer and sufficient for measurement, and fix it to the sample stage. (3) The content of sulfur, nitrogen, aluminum, chlorine, and lead in the sample is measured using an analytical instrument. (4) The measurement results of the five samples are averaged to determine the sulfur, nitrogen, aluminum, chlorine, and lead content in the final mixture containing thermoplastic resin or solid fuel.

[0119] <Method for measuring higher heating value, moisture content, and ash mass fraction> The higher heating value (MJ / kg) of the mixture containing the thermoplastic resin or solid fuel to be measured shall be determined by the method in accordance with JIS Z 7302-2. The mass fraction (%) of moisture in the mixture containing the thermoplastic resin or solid fuel to be measured shall be determined according to the method compliant with JIS Z 7302-3. The mass fraction (%) of ash content in the mixture containing the thermoplastic resin or solid fuel to be measured shall be determined according to the method compliant with JIS Z 7302-4.

[0120] <Method for measuring bulk density> The bulk density of a mixture containing thermoplastic resin or a solid fuel can be determined as follows: (1) Measure the total mass of the mixture containing the thermoplastic resin or the solid fuel when a container of a certain volume (e.g., 1 L) is filled to the brim with the mixture containing the thermoplastic resin or the solid fuel to be measured. (2) The bulk density of the mixture containing the thermoplastic resin or solid fuel to be measured is determined by dividing the measured mass by the mass of water equal to the volume of the container.

[0121] <Method for measuring E. coli> The method for measuring E. coli in mixtures or solid fuels containing thermoplastic resins is as follows: (1) Prepare 500g of an aqueous dispersion of the substance to be tested (a mixture containing thermoplastic resin or solid fuel) with a solid content concentration of 5.0% by mass in a 1-liter beaker. • If the above-mentioned object to be inspected is in a dry state The above aqueous dispersion can be formed by mixing the above-mentioned substance to be tested (25.0 g as solid content) with deionized water (in an amount that results in a total volume of 500.0 g). • When the above-mentioned substance to be tested exists in the form of an aqueous solution (for example, when the substance to be tested is recovered as an aqueous solution in the manufacturing method of the substance to be tested), and the solid content concentration of the substance to be tested is 5.0% by mass or more. By adding deionized water to the aqueous solution, a aqueous dispersion of the substance to be tested with a solid content concentration of 5.0% by mass can be prepared. • When the above-mentioned substance to be tested exists in an aqueous solution, and the solid content concentration of the substance to be tested is less than 5.0% by mass. By filtration, the solid content concentration of the substance to be tested can be adjusted to 5.0% by mass, or the aqueous solution itself can be used as an aqueous dispersion to increase the inoculation amount of the serially diluted sample described later (for example, if the solid content concentration of the substance to be tested is 2.5% by mass, the inoculation amount can be doubled). (2) Stir the above aqueous dispersion using an overhead stirrer at a rotation speed of 300 rpm for 15 minutes. (3) Place 50 mL of the aqueous dispersion, stirred using an overhead stirrer, into a sterile bag with a filter (LMS Co., Ltd. sterile bag with homogenizer filter) and stir for 5 minutes. (4) Dispense the aqueous dispersion, filtered through a sterile bag with a filter, into sterile test tubes, 10 -9 Prepare serially diluted samples by serially diluting the solution 10 times, dispensing the diluted solution into sterile test tubes, and so on. (5) The number of E. coli is measured by pour plate culture. Specifically, place 1 mL of serially diluted sample and 15-20 g of standard agar medium (Shioya MS Co., Ltd., EMB agar medium "Daigo" 399-02201 for E. coli testing) into a petri dish and incubate at 35°C for 48 hours using a pour plate. (6) The number of E. coli is counted by counting the number of colonies that have grown after culturing. Note 10 -9 If the number of colonies is zero in all serially diluted samples up to 10-fold, the target bacteria are determined to be "not detected," meaning that the total viable cell count detected by pour plate culture is below the detection limit. In other words, the total viable cell count is 0 cfu / g. (7) If colonies of intestinal bacteria or general viable bacteria are formed after culturing, the type of bacteria can be identified. Identification can be performed by biochemical characterization tests.

[0122] <Method for measuring polyphenol content> For measuring the polyphenol content in solid fuels, a total polyphenol analysis method compliant with ISO 14502-1:2005 "Determination of substances characteristic of green and black tea - Part 1: Content of total polyphenols in tea - Colorimetric method using Folin-Ciocalteu reagent" was used.

[0123] <Method for measuring catechin content> The method for measuring the catechin content in solid fuel is as follows: (1) Crush approximately 10g of the solid fuel to be measured in a mortar and pestle, and take out approximately 0.5g of the mixture after it has been thoroughly stirred. (2) Add 25 mL of solvent (an aqueous solution containing 70% by mass methanol), sonicate extract for 10 minutes, then centrifuge and filter the supernatant through a membrane filter to obtain the test solution. (3) Repeat the operation in (2) above to perform extraction a total of two times. (4) The test solution is measured using a liquid chromatograph mass spectrometer (LC-MS).

[0124] <Method for measuring odor components> The method for measuring the odor components in solid fuels is as follows: (1) Take 10g of the solid fuel to be measured as a sample. (2) Place the sample in a sampling bag and heat it under the conditions of 1 L of nitrogen filling, a heating temperature of 40°C, and a heating time of 30 minutes. (3) The gas inside the heated bag is measured by cold trap dehydration-gas chromatography-mass spectrometry (CTD-GC / MS). (4) Simultaneously with (3) above, the odor was detected at the column outlet using an odor sniffing device, and the odor was marked when an odor was detected. If the odor could be identified, the quality of the odor was recorded. (5) A library search and analysis were performed on the mass spectra of the detected components. The analysis will focus on components with low olfactory thresholds, components whose retention time is close to the time at which odor was detected by the odor sniffing device, and components whose detection concentration differed between samples. Assuming that the instrument sensitivity of all detected components is equal to that of toluene, the concentration converted to toluene will be calculated by comparing it with the peak area of ​​toluene. The equipment used for measurement and analysis is as follows: CTD (automatic concentrator): ENTECH ENT-7200 type GC / MS: Agilent GC7890B + MSD5977 and others Odor sniffing device: GERSTEL single PEC type Library: Wiley or NIST [Examples]

[0125] The present invention will be described below based on examples, but the present invention is not limited to these examples.

[0126] (1) Sample Reference Example 1: Using used disposable diapers as raw materials, a mixture containing the thermoplastic resin of Reference Example 1 was obtained by performing a crushing step S1 to a pressing, dehydration, and drying step S6, which is the first example of a method for producing a mixture of thermoplastic resin derived from used absorbent articles for use in the recycled molded articles according to this embodiment. However, the acidic aqueous solution in the second separation step S3 was a 0.1% by mass sulfuric acid aqueous solution, and the washing solution in the washing step S5 was water. Example 1: A mixture containing the thermoplastic resin of Reference Example 1 was used to form solid fuel by extrusion molding (10 kg / cm³) with 5% by mass of green tea leaves (size 5 mm or less) added. 2 , 150℃, 10 minutes). Comparative Example 1: A mixture containing the thermoplastic resin of Reference Example 1 was used without the addition of green tea leaves, and solid fuel was formed by extrusion molding (10 kg / cm³). 2 , 150℃, 10 minutes).

[0127] (2) Evaluation method (a) Components of a mixture containing thermoplastic resin For the mixture containing the thermoplastic resin in Reference Example 1, each component was measured according to the <Method for Measuring Components> described above. (b) Composition of mixtures containing thermoplastic resins and solid fuels, etc. For the mixture containing the thermoplastic resin of Reference Example 1, and the solid fuels of Example 1 and Comparative Example 1, the higher heating value, mass fractions of moisture and ash, content of sulfur, nitrogen, nitrogen, and lead, bulk density, and E. coli were measured using the above-described methods: <Method for measuring higher heating value and mass fraction of moisture and ash>, <Method for measuring sulfur, nitrogen, aluminum, chlorine, and lead content>, <Method for measuring bulk density>, and <Method for measuring E. coli>. (c) Polyphenol and catechin content of solid fuels The polyphenol and catechin content of the solid fuel of Example 1 was measured using the methods described above for measuring polyphenol content and catechin content. (d) The effect of tea leaves on odor For the solid fuels of Example 1 and Comparative Example 1, the changes in odor components were measured using the <Method for Measuring Odor Components> described above.

[0128] (3) Evaluation results (a) Components of a mixture containing thermoplastic resin The results of the component measurements for the mixture containing the thermoplastic resin in Reference Example 1 are shown in Table 1 below. In Reference Example 1, polypropylene and polyethylene, which are polyolefin resins, accounted for 46.2% by mass and 17.0% by mass, respectively. Polyethylene terephthalate, a polyester resin, accounted for 9.1% by mass. Styrene-containing polymer (styrene) accounted for 1.9% by mass. Hydrocarbons that may contain polyurethane accounted for 8.2% by mass. Other components, including butadiene, oligomers, and additives, accounted for 0.9% by mass and 0.3% by mass, respectively. Therefore, the thermoplastic resin accounted for 83.6% by mass. On the other hand, pulp fibers (cellulose) and inorganic compounds (calcium carbonate) accounted for 14.7% by mass and 1.7% by mass, respectively. Therefore, other components besides thermoplastic resin accounted for 16.4% by mass. Furthermore, the proportion of polyolefin resin in the thermoplastic resin was 75.6% by mass. In addition, the proportion of pulp fibers (cellulose) and inorganic compounds (calcium carbonate) in the other components was approximately 100% by mass. Furthermore, as will be described later, the mixture containing the thermoplastic resin in Reference Example 1 had extremely low levels of sulfur, chlorine, nitrogen, aluminum, and lead, and no E. coli was detected.

[0129] [Table 1]

[0130] (b) Composition of mixtures containing thermoplastic resins and solid fuels, etc. Table 2 below shows the measurement results for the composition of the thermoplastic resin mixture in Reference Example 1, and the solid fuels in Example 1 and Comparative Example 1. The thermoplastic resin mixture in Reference Example 1 had an extremely high higher heating value of 39.1 MJ / kg, and the content of moisture, ash, sulfur, chlorine, nitrogen, and aluminum was extremely low at 0.7% by mass, 2.7% by mass, 0.02% by mass, 0.02% by mass, less than 0.30% by mass, and less than 0.10% by mass, respectively, and no E. coli was detected. The bulk density was a relatively low 0.20. Therefore, except for the bulk density, it possessed characteristics that conformed not only to Grade A of the RPF (Refuse derived paper and plastics densified fuel) quality standard (JIS Z7311:2010 "Refuse derived paper, plastics, etc. solid fuel (RPF)"), but also to the RPF-coke grade. The solid fuel of Example 1 had an extremely high higher heating value of 35.7 MJ / kg, and its moisture, ash, sulfur, chlorine, nitrogen, aluminum, and lead content was extremely low at 1.0% by mass, 1.7% by mass, 0.01% by mass, 0.04% by mass, 0.48% by mass, 0.012% by mass, and less than 1% by mass, respectively. No E. coli was detected. The bulk density was 0.32. Therefore, it possessed characteristics that conformed not only to Grade A of RPF in the RPF quality standards, but also to RPF-coke. The solid fuel of Comparative Example 1 had an extremely high higher heating value of 36.5 MJ / kg, and its moisture, ash, sulfur, chlorine, nitrogen, and aluminum content was extremely low at 0.7% by mass, 2.1% by mass, 0.02% by mass, 0.04% by mass, less than 0.30% by mass, and less than 0.10% by mass, respectively. No E. coli was detected. The bulk density was 0.39. Therefore, it possessed characteristics that conformed not only to Grade A of the RPF quality standards but also to the RPF-coke variety.

[0131] [Table 2] *However, "less than XX" indicates the limit of quantification. "Not detected" means that the value is below the limit of quantification.

[0132] (c) Polyphenol and catechin content of solid fuels The polyphenol content of the solid fuel was 642 mg / kg (μg / g). Therefore, the polyphenol content of the solid fuel was 642 ppm by mass. The catechin content of the solid fuel was 3.6 μg / g. Therefore, the catechin content of the solid fuel was 3.6 ppm by mass.

[0133] (d) The effect of tea leaves on odor Table 3 below shows the results of measuring the effect of tea leaves on the odor of the solid fuels of Example 1 and Comparative Example 1. The estimated components obtained from the library search and the quality of the odor actually perceived by the odor sniffing device are shown in the table. It was found that the concentrations of hexanal, heptanal, and octanal decreased, and the odor was less noticeable, in the solid fuel with tea leaves (Example 1) compared to the solid fuel without tea leaves (Comparative Example 1).

[0134] [Table 3] However, "olfactory threshold" refers to the maximum concentration (literature value) at which a human nose can detect an odor. "Toluene equivalent value" refers to the value obtained by converting the detected component to the concentration of toluene. "Odor quality" indicates the presence or absence of an odor as determined by an odor-sniffing device; "○" indicates the presence of an odor, even if faint, and "×" indicates that no odor is detected.

[0135] The recycled molded articles and methods for manufacturing the same of the present invention are not limited to the embodiments described above, and can be appropriately combined or modified without departing from the purpose and spirit of the present invention.

Claims

1. A recycled molded article containing thermoplastic resin derived from used absorbent articles, The content of the thermoplastic resin is 60% by mass or more. Further containing plant-derived processed products containing polyphenols, Recycled molded material.

2. The aforementioned processed product contains tea leaves, The size of the aforementioned tea leaves is 5 mm or less. The recycled molded article according to claim 1.

3. The content of the processed material is 3 to 10% by mass. A recycled molded body according to claim 1 or 2.

4. The bulk density is 0.2 to 0.

5. The higher heating value is 25 MJ / kg or higher. A recycled molded body according to claim 1 or 2.

5. The moisture content is less than 5% by mass. The ash content is less than 5% by mass. The chlorine atom content is less than 0.2% by mass. The recycled molded body according to claim 4.

6. E. coli levels are below the detection limit. A recycled molded body according to claim 1 or 2.

7. A method for producing recycled molded articles containing thermoplastic resin derived from used absorbent articles, The process includes an addition step of adding a plant-derived processed product containing polyphenols to the mixture containing the thermoplastic resin before molding the mixture containing the thermoplastic resin. The content of the thermoplastic resin in the recycled molded article is 60% by mass or more. method.

8. The aforementioned processed product contains tea leaves, The size of the aforementioned tea leaves is 5 mm or less. The method according to claim 7.

9. The content of the processed material in the recycled molded body is 3 to 10% by mass. The method according to claim 7 or 8.

10. Prior to the additive step, the mixture containing the thermoplastic resin is further washed and dehydrated using an acid and / or organic solvent. The method according to claim 7 or 8.

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