Resin composition derived from used sanitary article containing excreta

Abstract

Provided is a resin composition derived from a used sanitary article containing excreta, which has improved moldability, processability, combustibility, hygiene, and safety, and can be used for various applications suitable for material recycling and thermal recycling. The resin composition derived from a used sanitary article containing excreta contains a soluble component and an insoluble component. The proportion of the soluble component is 80-90 mass%. The proportion of the insoluble component is 10-19 mass%. The proportion of nitrogen atoms contained in the resin composition is less than 0.5 mass%.

Description

Resin composition derived from used sanitary products containing excrement

[0001] The present invention relates to a resin composition derived from used sanitary products containing excrement.

[0002] Resin compositions recycled from sanitary goods and resin molded articles using the same are known. For example, Patent Document 1 discloses a pulp-containing resin molded article. The resin molded article contains a mixture of 19.8 to 50.5 wt % pulp fibers, 0.2 to 0.5 wt % superabsorbent polymer, and 49 to 80 wt % thermoplastic resin different from the superabsorbent polymer. The pulp fibers and superabsorbent polymer contained in the resin molded article may be recovered from the absorbent core of an absorbent article.

[0003] Patent No. 6402910

[0004] The resin molded article of Patent Document 1 is formed using a mixture or pellets thereof (hereinafter also referred to as the "resin composition") containing 19.8 to 50.5 wt% pulp fiber, 0.2 to 0.5 wt% superabsorbent polymer, and 49 to 80 wt% thermoplastic resin different from the superabsorbent polymer. The resin composition contains 20.0 wt% or more of pulp fiber and superabsorbent polymer, which are components that do not melt and / or are difficult to melt by heat (hereinafter also referred to as the "insoluble components"). Therefore, when attempting to form a resin molded article using the resin composition, the high content of insoluble components may make it difficult to mold or process.

[0005] Furthermore, the insoluble components tend not to contribute to combustion or tend to have a low calorific value, and therefore, when the resin composition is used to form a heat source such as a solid fuel, the insoluble components contained in the resin composition may result in low combustibility.

[0006] Furthermore, in the resin molding of Patent Document 1, when the pulp fibers and superabsorbent polymers are used in absorbent articles, they are removed from absorbent articles that have been lost due to production losses. Therefore, the absorbent articles are unused and do not contain excrement. Therefore, the resin composition containing the pulp fibers and superabsorbent polymer does not take into consideration impurities (including E. coli) derived from excrement.

[0007] However, in reality, the amount of absorbent articles generated as production losses is extremely small compared to the amount of used absorbent articles containing excrement. Therefore, from the perspective of reducing environmental impact, it is important to recycle materials derived from used absorbent articles containing excrement. In this case, in order to make resin compositions derived from used absorbent articles containing excrement into more hygienic, safe, and secure materials, it is necessary to keep the content of impurities derived from excrement low.

[0008] As described above, resin compositions derived from used sanitary products (including absorbent articles) containing excrement have room for improvement in at least moldability, processability, flammability, hygiene, and safety.

[0009] An object of the present invention is to provide a resin composition derived from used sanitary products containing excrement, which has improved moldability, processability, flammability, hygiene, and safety, and is suitable for material recycling and thermal recycling and can be used for various applications.

[0010] One aspect of the present invention is a resin composition derived from used sanitary products containing excrement, the resin composition comprising a soluble component and an insoluble component, the proportion of the soluble component being 80 to 90% by mass, the proportion of the insoluble component being 10 to 19% by mass, and the proportion of nitrogen atoms contained in the resin composition being less than 0.5% by mass.

[0011] Another aspect of the present invention is a sound-absorbing material comprising the resin composition according to the above aspect.

[0012] Yet another aspect of the present invention is a solid fuel containing the resin composition according to the above aspect and having a bulk specific gravity of 0.3 to 0.5.

[0013] Yet another aspect of the present invention is a container comprising the resin composition according to the above aspect.

[0014] According to the present invention, it is possible to provide a resin composition derived from used sanitary products containing excrement, which has improved moldability, processability, flammability, hygiene, and safety, and is suitable for material recycling and thermal recycling and can be used for various applications.

[0015] 1 is a flowchart showing a method for producing a resin composition derived from used sanitary products containing excrement according to an embodiment. 2 is a graph showing one characteristic of a sound-absorbing material using a resin composition derived from used sanitary products containing excrement according to an embodiment.

[0016] This embodiment relates to the following aspects: [Aspect 1] A resin composition derived from a used sanitary product containing excrement, the resin composition comprising a soluble component and an insoluble component, the proportion of the soluble component being 80 to 90% by mass, the proportion of the insoluble component being 10 to 19% by mass, and the proportion of nitrogen atoms contained in the resin composition being less than 0.5% by mass.

[0017] In this resin composition, the proportion of soluble components with a high calorific value and high solubility (i.e., high moldability, processability, and flammability) is 80% by mass or more, while the proportion of insoluble components with a low calorific value and low solubility (i.e., low moldability, processability, and flammability) is 19% by mass or less. Therefore, this resin composition has excellent moldability, processability, and flammability. Furthermore, this resin composition has a low proportion of insoluble components with low moldability and processability (i.e., low moldability, processability, and flammability) (i.e., low moldability, processability, and flammability). This enhances the stability of the product shape after molding or processing this resin composition, thereby increasing safety. Furthermore, this resin composition contains only less than 0.5% by mass of nitrogen atoms derived from excrement, resulting in minimal excrement-derived impurities. Therefore, this resin composition is a material with excellent hygiene and safety. Thus, this resin composition has excellent moldability, processability, and flammability, as well as excellent hygiene and safety, and is therefore suitable for material recycling and thermal recycling.

[0018] [Aspect 2] The resin composition according to Aspect 1, wherein the soluble component comprises a polyolefin as a main component. This resin composition contains a polyolefin having a high calorific value and a low melting point as a main component of the soluble component. Therefore, this resin composition has excellent moldability, processability, and flammability. Here, "main component" means that the main component accounts for 50% by mass or more of the soluble component.

[0019] [Aspect 3] The resin composition according to Aspect 1 or 2, wherein the soluble component further comprises a polyester-based resin. This resin composition further comprises, as a soluble component, a polyester-based resin that is difficult to mix with polyolefin. Therefore, in this resin composition, an air layer is easily formed between the polyolefin. As a result, this resin composition has better flammability and, in other applications, has excellent thermal insulation and sound insulation properties. The polyester-based resin is used, for example, as a fiber for the top sheet of an absorbent article for sanitary products.

[0020] [Aspect 4] The resin composition according to Aspect 3, wherein the polyester resin includes polyethylene terephthalate. This resin composition further includes polyethylene terephthalate, which is difficult to mix with polyolefins, as a soluble component. Therefore, in this resin composition, an air layer is easily formed between the polyolefin and the resin. As a result, this resin composition has better flammability and also has excellent thermal insulation and sound insulation properties for other applications.

[0021] [Aspect 5] The resin composition according to any one of Aspects 1 to 4, wherein the soluble component further comprises at least one of polyurethane and a styrene-containing polymer. This resin composition further comprises at least one of polyurethane and a styrene-containing polymer, which are difficult to mix with polyolefins, as soluble components. Therefore, in this resin composition, an air layer is easily formed between the polyurethane and / or the styrene-containing polymer and the polyolefin. This results in the resin composition having superior flammability, as well as excellent thermal insulation and sound insulation properties for other applications. The polyurethane and the styrene-containing polymer are used, for example, as elastic members or adhesives in absorbent articles for sanitary products.

[0022] [Aspect 6] The resin composition according to any one of Aspects 1 to 5, wherein the insoluble component includes at least one of cellulose-based fibers, superabsorbent polymers, and inorganic compounds. In this resin composition, the insoluble component includes at least one of pulp fibers, superabsorbent polymers, and inorganic compounds, which are difficult to mix with the soluble component. Therefore, in this resin composition, an air layer is likely to form between the soluble component and at least one of the pulp fibers, superabsorbent polymers, and inorganic compounds. This makes the resin composition more flammable and also provides excellent thermal insulation and sound insulation.

[0023] [Aspect 7] The resin composition according to any one of Aspects 1 to 6, wherein the resin composition contains less than 4% by mass of ash. In this resin composition, the ash content, which does not contribute to heat generation and has poor moldability, processability, and flammability, is only less than 4% by mass. Therefore, this resin composition has excellent moldability, processability, and flammability.

[0024] [Aspect 8] The resin composition according to any one of Aspects 1 to 7, wherein the proportion of chlorine atoms contained in the resin composition is less than 0.1% by mass. In this resin composition, the proportion of chlorine atoms, which poses safety issues when processed or reused, is only less than 0.1% by mass. Therefore, this resin composition is excellent in safety and reliability.

[0025] [Aspect 9] The resin composition according to any one of Aspects 1 to 8, wherein the amount of Escherichia coli contained in the resin composition is below the detection limit. In this resin composition, the amount of Escherichia coli derived from excrement, which is a hygiene problem when processed or reused, is below the detection limit. In other words, since the amount of excrement-derived impurities is extremely low, the resin composition is more excellent in terms of hygiene and safety.

[0026] [Aspect 10] The resin composition according to any one of Aspects 1 to 9, wherein the proportion of sulfur atoms contained in the resin composition is less than 0.1% by mass. In this resin composition, the proportion of sulfur atoms derived from excrement, which can cause hygiene problems when processed or reused, is only less than 0.1% by mass. In other words, since the content of excrement-derived impurities is extremely low, this resin composition is more hygienic and safe.

[0027] [Aspect 11] A sound-absorbing material comprising the resin composition according to any one of Aspects 1 to 10. The sound-absorbing material is formed using a resin composition containing 80 to 90 mass% of a soluble component with high moldability and processability, and 10 to 19 mass% of an insoluble component with low moldability and processability and difficult to mix with the soluble component. Therefore, the sound-absorbing material is prone to forming an air layer between the soluble component and the insoluble component. Therefore, the sound-absorbing material has excellent thermal insulation and sound-blocking properties while being formed into a desired shape. Furthermore, the resin composition contained in the sound-absorbing material contains less than 0.5 mass% of nitrogen derived from excrement, resulting in extremely low levels of excrement-derived impurities. Therefore, the sound-absorbing material is hygienic and offers excellent safety and security.

[0028] [Aspect 12] A solid fuel comprising the resin composition according to any one of Aspects 1 to 10, and having a bulk specific gravity of 0.3 to 0.5. This solid fuel is formed using a resin composition containing 80% by mass or more of soluble components with high calorific value and high combustibility, and 19% by mass or less of insoluble components with low calorific value and low combustibility, and has a bulk specific gravity of 0.3 to 0.5. Therefore, this solid fuel has excellent calorific value and combustibility.

[0029] [Aspect 13] A container comprising the resin composition according to any one of Aspects 1 to 10. The container is formed using a resin composition with excellent moldability and processability, containing 80% by mass or more of soluble components with high moldability and processability and 19% by mass or less of insoluble components with low moldability and processability. Therefore, the container can be easily formed into a desired shape. Furthermore, the container is formed using a resin composition with a proportion of excrement-derived nitrogen of less than 0.5% by mass and extremely low levels of excrement-derived impurities. Therefore, the container is hygienic and has excellent safety and security. Examples of containers include molded products formed using the resin composition, such as plastic bags, trash cans, pallets, buckets, and portable toilets.

[0030] Hereinafter, the resin composition derived from used sanitary products containing excrement according to this embodiment will be described.

[0031] Used sanitary products containing excrement are sanitary products that have been used and absorbed excrement (e.g., urine, feces, blood). However, when used sanitary products containing excrement are disposed of, for example, and are combined with used sanitary products that do not contain excrement and treated as a whole as used sanitary products containing excrement, used sanitary products containing excrement may also include used sanitary products that do not contain excrement. Here, used sanitary products that do not contain excrement include sanitary products that have been used but have not absorbed excrement, unused sanitary products, and sanitary products such as production waste. Examples of sanitary products include disposable diapers, urine absorption pads, incontinence pads, sanitary napkins, disposable shorts, bed sheets, and pet sheets.

[0032] This resin composition is a resin composition composed of substances derived from used sanitary products containing excrement, and contains soluble and insoluble components. Soluble components are components that dissolve and / or dissolve easily with heat. On the other hand, insoluble components are components that do not dissolve and / or are difficult to dissolve with heat. Here, "soluble / not soluble with heat" and "easy / difficult to dissolve with heat" refer to "melt / not melt / not melt" and "easy / difficult to dissolve" when heated, and the heating temperature is 280°C. In other words, soluble components are components with a melting point of 280°C or less, and insoluble components are components with a melting point above 280°C or components that do not melt but decompose thermally. Note that these components exclude metals.

[0033] The soluble components are not particularly limited as long as they are components commonly used as components of sanitary goods and satisfy the above-mentioned soluble component conditions. Examples of the soluble components 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.

[0034] The insoluble components are not particularly limited as long as they are components commonly used in sanitary goods and satisfy the above-mentioned requirements for the soluble components, such as cellulosic fibers, highly absorbent polymers, and inorganic substances.

[0035] Cellulosic fibers include, for example, natural cellulose fibers, regenerated cellulose fibers such as rayon, refined cellulose fibers such as lyocell, and semi-synthetic cellulose fibers such as acetate fibers. Natural cellulose fibers include, for example, pulp fibers such as wood pulp fibers and non-wood pulp fibers, and cotton fibers. Wood pulp fibers include, for example, softwood pulp fibers and hardwood pulp fibers. Non-wood pulp fibers include, for example, straw pulp fibers, bagasse pulp fibers, reed pulp fibers, kenaf pulp fibers, mulberry pulp fibers, bamboo pulp fibers, hemp pulp fibers, and cotton pulp fibers. Cotton fibers include hirsutum cotton fibers, barbadense cotton fibers, arboreum cotton fibers, and helbaceum cotton fibers. The cotton fibers may be organic cotton fibers or pre-organic cotton fibers. Organic cotton fiber means cotton that has been certified by GOTS (Global Organic Textile Standard).

[0036] Examples of superabsorbent polymers include starch-based, cellulose-based, and synthetic polymer-based polymer absorbents. Examples of starch-based or cellulose-based superabsorbent polymers include starch-acrylic acid (salt) graft copolymers, saponified starch-acrylonitrile copolymers, and crosslinked products of sodium carboxymethyl cellulose. Examples of synthetic polymer-based superabsorbent polymers include polyacrylates, polysulfonates, maleic anhydrides, polyacrylamides, polyvinyl alcohols, polyethylene oxides, polyaspartates, polyglutamates, and polyalginates.

[0037] Examples of inorganic substances include calcium carbonate, barium sulfate, calcium sulfate, barium carbonate, zinc oxide, magnesium oxide, titanium oxide, talc, silica, clay, kaolin, alumina, and mica.

[0038] In the present resin composition, the proportion of soluble components is 80 to 90% by mass. Thus, in the present resin composition, the proportion of soluble components that have a large calorific value and are easily soluble, i.e., have high moldability, processability, and flammability, is 80% by mass or more, which is very high. This allows the moldability, processability, and flammability of the present resin composition to be improved. Therefore, the present resin composition can be suitably used in applications requiring a large calorific value or applications requiring moldability and processability. The upper limit of 90% by mass is determined in relation to the proportion of other components, such as insoluble components.

[0039] On the other hand, the proportion of insoluble components is 10 to 19% by mass. Thus, in the present resin composition, the proportion of insoluble components, which have a low calorific value and are difficult to dissolve, i.e., have low moldability, processability, and flammability, is 10% by mass or more, and a small amount is present. This improves the shape stability of products molded or processed from the present resin composition, and also increases safety during use. The upper limit of 90% by mass is determined in relation to the proportion of insoluble components. The upper limit of 19% by mass is determined in relation to the proportion of other components, such as soluble components.

[0040] Because the resin composition is composed of substances derived from used sanitary products containing excrement, it may contain organic substances (nitrogen compounds) containing nitrogen atoms present in the excrement. However, in the resin composition, the proportion of nitrogen atoms is suppressed to less than 0.5 mass%. In this way, the resin composition can suppress the proportion of nitrogen atoms derived from organic substances in the excrement to an extremely low level, thereby improving the hygiene and safety of the resin composition.

[0041] As described above, the resin composition of the present invention is a material that is excellent in moldability, processability, and flammability, as well as in hygiene and safety, and is therefore suitable for material recycling and thermal recycling.

[0042] Next, an example of the configuration of a sanitary product (absorbent article) will be described. The sanitary product comprises a top sheet, a back sheet, and an absorbent body disposed between the top sheet and the back sheet. The size of the sanitary product can be, for example, approximately 15 to 100 cm in length and 5 to 100 cm in width, but is not limited to this example. The sanitary product may further comprise other components commonly found in sanitary products, such as a diffusion sheet, a leak-proof wall, a side sheet, an outer sheet, and thread-like or sheet-like elastic members disposed on the leak-proof wall or outer sheet.

[0043] Examples of constituent materials for the top sheet include liquid-permeable nonwoven fabrics, synthetic resin films with liquid-permeable holes, and composite sheets thereof. Examples of constituent materials for the back sheet include liquid-impermeable nonwoven fabrics, liquid-impermeable synthetic resin films, and composite sheets thereof. Examples of constituent materials for the diffusion sheet include liquid-permeable nonwoven fabrics. Examples of constituent materials for the leak-proof walls and side sheets include water-repellent nonwoven fabrics. Examples of constituent materials for the exterior sheet include liquid-impermeable and breathable nonwoven fabrics, liquid-impermeable and breathable synthetic resin films, and composite sheets thereof. Examples of constituent materials for the elastic member include rubber-based synthetic resins. There are no particular limitations on the type of nonwoven fabric, and examples include meltblown nonwoven fabrics, spunbond nonwoven fabrics, air-laid nonwoven fabrics, and air-through nonwoven fabrics. There are no particular limitations on the type of synthetic resin film, and known film materials can be used. The materials for the nonwoven fabrics and synthetic resin films are not particularly limited as long as they can be used for sanitary products, and examples thereof include olefin-based resins such as polyethylene and polypropylene, polyamide-based resins such as 6-nylon and 6,6-nylon, and polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate. Cellulose-based fibers may also be used as nonwoven fabric materials. To impart breathability, synthetic resin films may contain inorganic particles such as calcium carbonate. The rubber-based synthetic resin materials are not particularly limited as long as they can be used for sanitary products, and examples thereof include styrene butadiene rubber and urethane rubber. These nonwoven fabrics and synthetic resin film materials are synthetic resins and can be considered plastic materials.

[0044] The absorbent body may include absorbent materials such as at least one of cellulose-based fibers and superabsorbent polymers. Examples of cellulose-based fibers include natural cellulose fibers, such as pulp fibers (e.g., wood pulp fibers, crosslinked pulp fibers, and non-wood pulp fibers), regenerated cellulose fibers, and semi-synthetic cellulose fibers. Pulp fibers may have an average fiber length of, for example, several tens of microns, preferably 20 to 40 microns, and an average fiber length of, for example, several millimeters, preferably 2 to 5 mm. Examples of superabsorbent polymers (SAPs) include polyacrylate-based, polysulfonate-based, and maleic anhydride-based water-absorbing polymers. The size (when dry) of the superabsorbent polymer may be, for example, an average particle size of several hundred microns, preferably 200 to 500 microns. The absorbent body may include a core wrap formed from a liquid-permeable sheet.

[0045] One side and the other side of the absorbent body are bonded to the top sheet and the back sheet, respectively, via an adhesive. In plan view, the portion (peripheral portion) of the top sheet that extends outward from the absorbent body so as to surround the absorbent body is bonded via an adhesive to the portion (peripheral portion) of the back sheet that extends outward from the absorbent body so as to surround the absorbent body. Therefore, the absorbent body is enclosed within the bonded body of the top sheet and the back sheet. There are no particular limitations on the adhesive, and examples include hot melt adhesives. Examples of hot melt adhesives include pressure-sensitive adhesives or heat-sensitive adhesives that are primarily rubber-based, such as styrene-ethylene-butadiene-styrene, styrene-butadiene-styrene, styrene-isoprene-styrene, polyurethane, or polyolefin-based, such as polyethylene.

[0046] In a preferred embodiment of the present invention, the soluble component contains a polyolefin resin as a main component. The term "main component" refers to a proportion of the soluble component of 50% by mass or more. The polyolefin resin refers to a polymer containing an olefin (e.g., ethylene, propylene, butylene, etc.) or a diolefin (e.g., butadiene, isoprene, etc.) as a constituent element. Examples of polyolefin resins include polyethylene and polypropylene. Thus, in the present resin composition, the soluble component contains a large amount of polyolefin resin, which has a high calorific value and a low melting point. This results in the present resin composition having superior moldability, processability, and flammability.

[0047] The proportion of the polyolefin resin in the dissolved components is preferably 60% by mass, more preferably 70% by mass, as a lower limit from the viewpoints of moldability, processability, and flammability. There is no particular upper limit. However, when it is preferable to contain other resins depending on the application of the resin composition (e.g., heat insulating members or sound insulating members), the proportion may be, for example, 85% by mass.

[0048] In a preferred embodiment of the present invention, the soluble component further contains a polyester resin. Examples of polyester resins include polyethylene terephthalate and polybutylene terephthalate. In this manner, the soluble component of the present resin composition further contains a polyester resin that is difficult to mix with polyolefin resins, which facilitates the formation of an air layer between the polyester resin and the polyolefin resin. This provides the present resin composition with superior flammability and, in other applications, excellent thermal insulation and sound insulation.

[0049] The proportion of the polyester resin in the dissolved components is preferably 3% by mass, more preferably 6% by mass, as a lower limit from the viewpoint of heat insulation and sound insulation, and is preferably 15% by mass, more preferably 12% by mass, as an upper limit from the viewpoint of moldability and processability.

[0050] In a preferred aspect of this embodiment, the soluble components further contain at least one of a polyurethane resin and a styrene-containing polymer. Examples of polyurethane resins include polyurethane, and examples of styrene-containing polymers include styrene-ethylene-butadiene-styrene, styrene-butadiene-styrene, and styrene-isoprene-styrene. In this manner, in the present resin composition, at least one of a polyurethane resin and a styrene-containing polymer, which are difficult to mix with polyolefin resins, is further contained in the soluble components. This facilitates the formation of an air layer between the polyolefin resin and at least one of the polyurethane resin and the styrene-containing polymer. This provides the present resin composition with superior flammability and, in other applications, excellent thermal insulation and sound insulation.

[0051] The proportion of at least one of the polyurethane resin and the styrene-containing polymer in the dissolved components is preferably 3% by mass, more preferably 6% by mass, from the viewpoints of heat insulation and sound insulation, and is preferably 15% by mass, more preferably 12% by mass, from the viewpoints of moldability and processability.

[0052] In a preferred embodiment of the present invention, the insoluble component includes at least one of cellulose-based fibers, superabsorbent polymers, and inorganic compounds. Examples of cellulose-based fibers include pulp fibers. Examples of superabsorbent polymers include polyacrylate-based, polysulfonate-based, and maleic anhydride-based water-absorbing polymers. Examples of inorganic compounds include calcium carbonate, zinc oxide, magnesium oxide, and alumina. In this resin composition, the insoluble component includes at least one of pulp fibers, superabsorbent polymers, and inorganic compounds that are difficult to mix with the soluble component. This facilitates the formation of an air layer between the soluble component and at least one of the pulp fibers, superabsorbent polymers, and inorganic compounds. This allows the resin composition to have excellent flammability and other applications, such as thermal insulation and sound insulation.

[0053] The proportion of at least one of the pulp fiber, the superabsorbent polymer, and the inorganic compound in the insoluble component is preferably 80% by mass or more, more preferably 90% by mass, from the viewpoint of heat insulation and sound insulation. There is no particular upper limit.

[0054] In a preferred embodiment of the present invention, the resin composition contains less than 4% by mass of ash, which does not contribute to heat generation and has poor moldability, processability, and flammability. As a result, the resin composition has excellent moldability, processability, and flammability.

[0055] In a preferred embodiment of the present invention, the proportion of chlorine atoms contained in the resin composition is less than 0.1% by mass. Thus, in the present resin composition, the proportion of chlorine atoms that poses safety issues when processed or reused is only less than 0.1% by mass. Therefore, the present resin composition is excellent in safety and security.

[0056] Since the resin composition is composed of substances derived from used sanitary products containing excrement, it may contain E. coli present in the excrement. However, in a preferred aspect of this embodiment, the amount of E. coli contained in the resin composition is below the detection limit. Thus, in the resin composition, the amount of E. coli derived from excrement, which is a hygiene problem when processing or reusing the resin composition, is below the detection limit. In other words, since the amount of impurities derived from excrement is extremely low, the resin composition is more hygienic and safe.

[0057] Because the resin composition is composed of substances derived from used sanitary products containing excrement, it may contain organic substances (sulfur compounds) that are present in the excrement and have sulfur atoms. However, in a preferred embodiment of the present invention, the proportion of sulfur atoms in the resin composition is suppressed to just less than 0.1 mass%. In this way, the proportion of sulfur atoms derived from excrement, which poses hygiene problems during processing and reuse, can be extremely reduced in the resin composition, thereby improving the hygiene and safety of the resin composition.

[0058] Next, a sound-absorbing material containing the resin composition according to this embodiment will be described. The sound-absorbing material can use the resin composition described above. However, when used, the resin composition is retained in a predetermined area to form a desired overall shape. For example, the resin composition can be packed into a resin container, i.e., retained in a region within the container, to form a plate-shaped sound-absorbing material. If necessary, multiple containers (sound-absorbing members) filled with the resin composition can be arranged or stacked as needed. An example of a container filled with the resin composition is a polyolefin resin bag measuring (400-600 mm) x (400-600 mm) x (20-100 mm). By packing 1 to 5 kg of the resin composition into the bag, a predetermined plate-shaped sound-absorbing material can be formed. Alternatively, for example, the resin composition can be packed between two walls, i.e., retained in the region between the two walls, to form a wall-shaped sound-absorbing material.

[0059] This sound-absorbing material is formed using a resin composition containing 80 to 90% by mass of a soluble component with high moldability and processability, and 10 to 19% by mass of an insoluble component with low moldability and processability that is difficult to mix with the soluble component. Therefore, this sound-absorbing material is prone to forming an air layer between the soluble and insoluble components. This allows the sound-absorbing material to be formed into a desired shape while providing excellent thermal and sound insulation properties. Furthermore, the resin composition contained in this sound-absorbing material contains less than 0.5% by mass of nitrogen derived from excrement, resulting in extremely low levels of excrement-derived impurities. This makes the sound-absorbing material hygienic and safe.

[0060] The sound-absorbing material has excellent heat insulation properties as well as sound insulation properties, and can therefore also be used as a heat insulation material. The structure of the heat insulation material can be the same as that of the sound-absorbing material. As a result, the heat insulation material has excellent heat insulation and sound insulation properties, is hygienic, and is safe and secure.

[0061] Next, a solid fuel containing the resin composition according to this embodiment will be described. The solid fuel is formed by extrusion molding using the resin composition described above. There are no particular restrictions on the pressure and temperature of the extrusion molding, as long as the solid fuel can be formed. The pressure is, for example, 5 to 50 kg / cm. ２The temperature may be, for example, 100 to 200°C. The bulk density of the solid fuel is preferably 0.3 to 0.5. If the bulk density is too small, the calorific value may be too low, and if the bulk density is too large, the heat may be too strong.

[0062] This solid fuel is formed using a resin composition containing 80% by mass or more of soluble components with high calorific value and high combustibility, and 19% by mass or less of insoluble components with low calorific value and low combustibility, and has a bulk specific gravity of 0.3 to 0.5. Therefore, this solid fuel has excellent calorific value and combustibility.

[0063] Next, a container containing the resin composition according to this embodiment will be described. Examples of this container include molded products molded using the resin composition, such as plastic bags, trash cans, pallets, buckets, and portable toilets. Plastic bags are formed, for example, by an inflation method or a die method using the above-described resin composition. Other molded products are formed, for example, by extrusion molding using the above-described resin composition.

[0064] This container is formed using a resin composition with excellent moldability and processability, containing 80% by mass or more of soluble components with high moldability and processability and 19% by mass or less of insoluble components with low moldability and processability. Therefore, this container can be easily formed into a desired shape. Furthermore, this container is formed using a resin composition with a proportion of excrement-derived nitrogen of less than 0.5% by mass and extremely low levels of excrement-derived impurities. Therefore, this container is hygienic and offers excellent safety and security.

[0065] Next, the method for producing a resin composition derived from used sanitary products containing excrement according to this embodiment will be specifically described. In this embodiment, a disposable diaper will be taken as an example of the sanitary product.

[0066] FIG. 1 is a flowchart illustrating a method for producing a resin composition from used sanitary products containing excrement according to the present embodiment. This method includes a first separation step S2, a second separation step S3, and a washing step S5. The resulting plastic material can be used as a resin composition. In this embodiment, the method further includes a crushing step S1, an air conveying step S4, and a compression dehydration drying step S6. This reduces the amount of impurities in the resulting plastic material. In this embodiment, the method further includes 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. 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, a resin composition with a further adjusted proportion of insoluble components can be formed. A detailed description is provided below.

[0067] In this embodiment, used sanitary products are collected from outside for reuse (recycling). In this case, multiple used sanitary products are sealed in a collection bag to prevent excrement, bacteria, and odors from leaking to the outside. Each used sanitary product in the collection bag is collected, for example, rolled or folded with the top sheet on which excrement is excreted facing inward, so that excrement and bacteria are not exposed to the outside and odors are not diffused to the surrounding area. Note that the used sanitary products do not have to be sealed in the collection bag or rolled up.

[0068] The crushing step S1 is a step of crushing used absorbent articles together with an inactivating aqueous solution containing an inactivating agent that inactivates the superabsorbent polymer. The crushing step S1 is carried out using a crushing device such as a biaxial crusher. Crushing together with an inactivating aqueous solution includes crushing used absorbent articles while supplying them to the crushing device together with the inactivating aqueous solution, crushing used absorbent articles in the inactivating aqueous solution stored in the crushing device, and combinations thereof. In this embodiment, used absorbent articles are crushed while being supplied to the crushing device together with the inactivating aqueous solution. In this method, when an inactivating aqueous solution is used in the first separation step S2 or later, the inactivating aqueous solution is replenished as needed when it runs short.

[0069] In this embodiment, collection bags containing used absorbent articles are supplied to a receiving device and then moved to a crushing device connected to the receiving device below. At the same time, an inactivating aqueous solution (e.g., an acidic aqueous solution) is supplied to the crushing device via the receiving device. The inactivating aqueous solution may be supplied so that it falls onto the used absorbent articles from above. This is to prevent the scattering of crushed material (including substances derived from excrement, such as bacteria and odorous substances) during crushing. The collection bag is crushed together with the inactivating aqueous solution by the crushing device. The used absorbent articles in the collection bag are crushed together with the collection bag in the inactivating aqueous solution, producing crushed material with a size of, for example, 1 to 150 mm. During this process, the superabsorbent polymer is inactivated and dehydrated by the inactivating aqueous solution, resulting in small particle sizes. The crushed material is sent to the first separation step S2 together with the inactivating aqueous solution.

[0070] 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. Compared to using an aqueous solution such as lime or calcium chloride, the use of an acidic aqueous solution makes it less likely that ash or chlorine will remain in plastic materials, superabsorbent polymers, pulp fibers, etc., 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 is chlorine-free and low-cost, is preferred. Note that the inactivation aqueous solution may be an aqueous solution containing a known polyvalent metal ion source capable of supplying polyvalent metal ions.

[0071] The pH of the acidic aqueous solution is preferably 1.0 to 4.0. A pH of 1.0 or higher makes equipment less susceptible to corrosion and reduces the amount of alkaline chemicals required for neutralization during wastewater treatment, while a pH of 4.0 or lower allows the superabsorbent polymer to be sufficiently small and enhances sterilization ability. Since pH varies depending on water temperature, the pH in the present invention refers to the pH measured at an aqueous solution temperature of 20°C. The concentration of the acidic aqueous solution is not particularly limited, but is preferably 0.5 to 4 mass% in the case of citric acid and 0.1 to 2.0 mass% in the case of sulfuric acid.

[0072] During the shredding step S1, the heat generated during shredding and / or the heat of the acidic aqueous solution can reduce the adhesive strength of the adhesive (e.g., hot melt adhesive) between the components, allowing the components to be easily separated from each other. Alternatively, heating the acidic aqueous solution (temperature: 70 to 95°C) can soften the adhesive (e.g., hot melt adhesive) used to bond the components of the used absorbent article, thereby reducing the adhesive's adhesive strength. This allows the components to be easily separated from each other naturally or with a small impact. It also makes it possible to more effectively sterilize (disinfect) the used absorbent article.

[0073] Next, in the first separation step S2, the mixture of plastic material, inactivated superabsorbent polymer, pulp fiber, excrement, and inactivating aqueous solution supplied from the shredding step S1 is separated into a first fraction containing plastic material and a second fraction containing inactivated superabsorbent polymer, pulp fiber, excrement, and inactivating aqueous solution. The first separation step S2 is carried out by a separation device such as a screen separator, a pulper separator, or a combination thereof.

[0074] In this embodiment, the acidic aqueous solution containing the crushed material produced in the shredding process S1 is stored and stirred in the pulper separator, and the crushed material is disintegrated into constituent materials. The acidic aqueous solution containing the crushed material (disintegrated constituent materials) is then separated through a screen, and a second fraction containing inactivated superabsorbent polymer, pulp fibers, excrement, and the acidic aqueous solution is accepted and sent to the dust removal process S7. Meanwhile, the first fraction, including the collection bags, film, nonwoven fabric, etc., is rejected and sent to the second separation process S3. The separated collection bags, film, nonwoven fabric, etc. can be considered plastic materials. Note that a different acidic aqueous solution not used in the shredding process S1 may be supplied to the first separation process S2 as the acidic aqueous solution. In this case, some of the pulp fibers, superabsorbent polymer, and excrement may not pass through the screen and may remain on the screen along with the first fraction. Meanwhile, some of the collection bags, film, and nonwoven fabric may pass through the screen along with the second fraction.

[0075] In this embodiment, if the superabsorbent polymer is inactivated and granulated to reduce its water absorption capacity before the first separation step S2 (such as in the crushing step S1), the inactivating aqueous solution (acidic aqueous solution) may not be used in the first separation step S2 and thereafter, and the inactivating aqueous solution may be largely removed before using water (aqueous solution) that does not contain an inactivating agent. In this case, water (aqueous solution) that does not contain an inactivating agent may be used from any step after the first separation step S2. This reduces the amount of inactivating aqueous solution (and inactivator) used and reduces the burden on wastewater treatment.

[0076] In this embodiment, in the first separation step S2, the pH of the acidic aqueous solution may be adjusted to be maintained within a predetermined range. The predetermined pH range refers to a pH fluctuation range of ±1.0 or less. This allows the difference between the specific gravity and size of the superabsorbent polymer and the specific gravity and size of the pulp fiber to be within a predetermined range. In this case, the difference within the predetermined range refers, for example, to a difference of 0.2 to 5 times that of the other. This allows the difference between the pulp fiber and the superabsorbent polymer to be within a predetermined range in specific gravity and a predetermined range in size. As a result, the pulp fiber and the superabsorbent polymer can be easily separated from other materials (mainly plastic materials) of the used absorbent article by utilizing the differences in size and specific gravity. The pH can be adjusted using an acidic or alkaline aqueous solution from a pH adjustment device installed in the separation device based on the pH value measured by a pH sensor installed in the separation device. The pH may also be adjusted in a similar manner in at least one of the dust removal step S7, the second separation step S3, and the SAP separation step S8, which will be described later.

[0077] The second separation step S3 is a step of applying a physical impact to the first fraction to separate the plastic material from the pulp fibers, superabsorbent polymer, and excrement that remained in the first fraction and were not completely separated in the first separation step S2. That is, in the second separation step S3, the plastic material and the remaining pulp fibers, superabsorbent polymer, and excrement are separated from the mixture of the plastic material and the remaining pulp fibers, superabsorbent polymer, and excrement. In this way, the plastic material is recovered.

[0078] In this embodiment, the second separation step S3 involves treating the first fraction with an acidic aqueous solution while applying a physical impact to the first fraction to separate it. Specifically, in the second separation step S3, the mixture (plastic material and residue) from which the pulp fibers, superabsorbent polymer, excrement, and acidic aqueous solution were separated in the first separation step S2 is first supplied to a separation device. The separation device includes a cylindrical portion installed sideways, multiple impellers disposed within the cylindrical portion, multiple acidic aqueous solution supply units disposed on the upper outer peripheral surface of the sideways-positioned cylindrical portion, and a screen disposed on the lower outer peripheral surface of the cylindrical portion. A mixture supply port is provided at one end of the cylindrical portion, and a discharge port is provided at the other end. The multiple impellers are arranged at intervals along the central axis of the cylindrical portion so that their rotation axes overlap the central axis of the cylindrical portion. The orientation of the blades of the multiple impellers is adjusted to generate an air flow from one end of the cylindrical portion to the other end while rotating around the central axis of the cylindrical portion. The plurality of acidic aqueous solution supply units are arranged at intervals along the central axis and spray new acidic aqueous solution downward toward the cylindrical portion. The acidic aqueous solution supply units preferably spray the acidic aqueous solution in the form of a spray. The size of each opening in the screen is large enough to allow pulp fibers and superabsorbent polymer (excrement, acidic aqueous solution) to pass through, but large enough to prevent plastic materials from passing through.

[0079] The mixture is sprayed with acidic aqueous solutions from each of the multiple acidic aqueous solution supply units in the air within the cylindrical section of the separation device, agitated by the blades of the rotating impeller, and subjected to physical impacts caused by the collisions of the impeller blades, moving (flowing) from one end of the cylindrical section to the other. During this time, the mixture is washed free of dirt and / or sterilized or bleached by the sprayed acidic aqueous solutions. At the same time, pulp fibers and other components in the mixture are removed from the plastic material in the mixture by physical impacts and further inactivation by the acidic aqueous solutions, and the superabsorbent polymer in the mixture is removed from the plastic material in the mixture by physical impacts and other factors. The removed pulp fibers and superabsorbent polymer pass through a screen below the cylindrical section and are separated (removed) along with the acidic aqueous solution.

[0080] On the other hand, the plastic material in the mixture from which the pulp fibers, superabsorbent polymer, etc. have been removed does not pass through the screen and is discharged from the outlet at the other end of the cylindrical portion. That is, the superabsorbent polymer and pulp fibers that remained without being separated in the first separation step S2 are removed, and a plastic material with reduced impurities is produced and recovered. However, although not necessarily in large amounts, sulfur compounds and nitrogen compounds derived from excrement that were not completely removed in the second separation step S3 may remain in the plastic material. The separated acidic aqueous solution may be reused in the first separation step S2 and the crushing step S1. The acidic aqueous solution is as described above.

[0081] The amount of the acidic aqueous solution to be supplied is not particularly limited as long as it can achieve the desired function, but for example, the weight of the acidic aqueous solution relative to the weight of the plastic material is 5 to 100 times, preferably 10 to 50 times. The supply rate of the acidic aqueous solution is not particularly limited as long as it can achieve the desired function, but for example, it is 50 to 500 cm ３ / min, and 80 to 200 cm ３ If the supply amount or supply rate is too small, it is difficult to obtain the desired effect, whereas if it is too large, there is a risk of damaging the equipment, materials, etc.

[0082] In a preferred embodiment of the second separation step S3, an acidic aqueous solution is sprayed onto the mixture. The force of the spray can wash away any remaining superabsorbent polymer and pulp fibers adhering to the plastic material. Furthermore, the spray breaks down the acidic aqueous solution into fine particles, making it easier for the acidic aqueous solution to reach the superabsorbent polymer remaining in the fine details of the plastic material. Furthermore, compared to immersing the plastic material in an acidic aqueous solution, fresh acidic aqueous solution can be constantly supplied to the surface of the plastic material, reducing variations in the effectiveness of the acidic aqueous solution.

[0083] In the second separation step S3, separation may be performed by applying physical impact to the first fraction without treating the first fraction with an acidic aqueous solution. The mixture is agitated by rotating impeller blades in the air inside the cylindrical portion of the separation device, and moves (flows) from one end of the cylindrical portion to the other while being subjected to physical impact by the collision of the impeller blades. During this process, dirt is knocked off the mixture by the physical impact. For example, pulp fibers and superabsorbent polymers in the mixture are removed from the plastic material in the mixture by the physical impact. The removed pulp fibers and superabsorbent polymers pass through a screen below the cylindrical portion and are separated (removed).

[0084] Alternatively, in the second separation step S3, instead of the acidic aqueous solution, water or an aqueous solution not containing a deactivating agent (hereinafter simply referred to as "water") may be sprayed onto the first fraction. The mixture is sprayed with water from each of the multiple water supply units that supply water in the air within the cylindrical section of the separation device, agitated by the blades of a rotating impeller, and subjected to physical impacts caused by the collision of the impeller blades, causing the mixture to move (flow) from one end of the cylindrical section to the other. During this process, dirt is washed away from the mixture by the sprayed water, and the dirt is knocked off by the physical impact. For example, the pulp fibers and superabsorbent polymer in the mixture are removed from the plastic material in the mixture by the flow of water and the physical impact. The removed pulp fibers and superabsorbent polymer pass through a screen below the cylindrical section and are separated (removed) together with the water.

[0085] The pneumatic conveying step S4 (conveying step) is a step of conveying the plastic material separated in the second separation step S3 by air to the cleaning step S5. That is, in the pneumatic conveying step S4, the separated plastic material is dried in the air flow while being conveyed to the next step.

[0086] In this embodiment, in the air conveying step S4, the separated plastic material is conveyed from the separating device in the second separation step S3 to the cleaning device (described later) in the cleaning step S5 by air flowing through the pipe driven by a blower. During this process, the moisture contained in the plastic material is evaporated or blown away into the air, thereby reducing the moisture content of the plastic material. The moisture content decreases, for example, from approximately 95% to approximately 80%. Furthermore, the air flow can separate multiple plastic materials. As a result, when a cleaning solution is used in the subsequent cleaning step S5, the cleaning solution can be supplied uniformly to the entire surface of each plastic material. The air conveying step S4 need not be used, and the separated plastic material may be conveyed by other known conveying means.

[0087] The washing step S5 is a step of spraying a washing liquid onto the plastic material separated in the second separation step S3. That is, in the washing step S5, sulfur compounds and nitrogen compounds derived from excrement that were not completely removed in the second separation step S3 and remain in the plastic material are removed by the washing liquid. Furthermore, other impurities such as pulp fibers and superabsorbent polymers that may remain in trace amounts can also be removed by the washing liquid.

[0088] In this embodiment, in the cleaning step S5, the plastic material separated in the second separation step S3 (via the air conveying step S4) is supplied to a cleaning device. The cleaning device includes a conveyor (in this embodiment, a screw conveyor) that transports the plastic material, and multiple cleaning liquid supply units that are provided above the conveyor and spray cleaning liquid onto the plastic material being transported. The conveyor is inclined upward along the conveyance direction (e.g., at an angle of 30°), thereby carrying the sprayed cleaning liquid that spills from the plastic material to a drain outlet below. The multiple cleaning liquid supply units are arranged at intervals along the conveyance direction of the conveyor. It is preferable that the cleaning liquid supply units spray the cleaning liquid in a spray form.

[0089] The plastic material is conveyed from one end to the other end by a conveyor while being sprayed with cleaning liquid from each of a plurality of cleaning liquid supply units. During this time, the plastic material is physically agitated by the screw conveyance while being sprayed with cleaning liquid. The sprayed cleaning liquid washes away sulfur compounds and nitrogen compounds derived from excrement remaining on the plastic material, washing them away and mixing them into the cleaning liquid. In other words, sulfur compounds and nitrogen compounds remaining on the plastic material are removed. Furthermore, if the cleaning liquid has a bactericidal effect, it can sterilize the plastic material. If the cleaning liquid is an oxidizing agent, sulfur compounds and nitrogen compounds are oxidized to produce other odorless substances (e.g., sulfur (S) and nitrogen (N)). ２ ) and are mixed into the cleaning solution and / or released as a gas. This means that sulfur and nitrogen compounds remaining in the plastic material are removed. The cleaning solution also sterilizes the plastic material.

[0090] In the cleaning step S5, the cleaning solution is sprayed onto the plastic material. The force of the spray can wash away sulfur compounds, nitrogen compounds, and other impurities adhering to the surface of the plastic material. Furthermore, the spray breaks down the cleaning solution into fine particles, making it easier for the cleaning solution to reach the sulfur compounds and nitrogen compounds remaining in the fine details of the plastic material. Furthermore, compared to immersing the plastic material in the cleaning solution, fresh cleaning solution can be constantly supplied to the surface of the plastic material, reducing variations in the cleaning solution's effectiveness (e.g., cleaning and sterilization effects).

[0091] Here, the cleaning solution may be, for example, an oxidizer aqueous solution, which is an aqueous solution containing an oxidizer, or water. The oxidizer may contain at least one of ozone and hydrogen peroxide. Depending on the amount of impurities in the plastic material, water may be, for example, water at room temperature and atmospheric pressure, high-temperature and / or high-pressure water or steam, or superheated steam. A disinfectant may also be included. In this embodiment, an oxidizer aqueous solution is used, and ozone is used as the oxidizer from the viewpoint of oxidizing, disinfecting, and bleaching power. Specifically, the oxidizer aqueous solution is ozone water, which is water (or an aqueous solution) such as pure water or clean water, mixed with ozone gas. The oxidizer aqueous solution may be acidic to prevent ozone deactivation. Furthermore, when an acidic aqueous solution such as a (dilute) sulfuric acid aqueous solution is used as the inactivation aqueous solution in at least the second separation step S3 of the crushing step S1, the first separation step S2, and the second separation step S3, the acidic solution may be used from the viewpoint of the continuity of each step and the effective use of the aqueous solution. In this case, an acidic aqueous solution (e.g., a dilute sulfuric acid aqueous solution) mixed with ozone gas is used. As the acidic aqueous solution, an acidic aqueous solution used in another step may be reused.

[0092] The ozone concentration in the aqueous oxidizing solution is not particularly limited, as long as it is a concentration that can achieve the desired function, i.e., oxidizing, disinfecting, and bleaching power against sulfur compounds (including sulfuric acid in an acidic aqueous solution) and nitrogen compounds. Examples of the concentration include 0.2 to 10 ppm, with 0.5 to 5 ppm being preferred. A concentration that is not too low can achieve the desired function, while a concentration that is not too high can suppress corrosion of equipment. The treatment time with the aqueous oxidizing solution is not particularly limited, as long as it can achieve the desired function; however, the higher the ozone concentration in the aqueous oxidizing solution, the shorter the treatment time, and the lower the ozone concentration, the longer the treatment time, typically 1 to 30 minutes. The product of the ozone concentration (ppm) in the aqueous oxidizing solution and the treatment time (minutes) of the treatment step (hereinafter also referred to as the "CT value") is, for example, 0.5 to 200 ppm-minute, with 5 to 100 ppm-minute being preferred. A CT value that is not too low can achieve the desired function, while a CT value that is not too high can suppress corrosion of equipment. The aqueous oxidizing agent solution used in the oxidizing agent treatment step S9 described later may be reused in this step after reducing the concentration.

[0093] The amount of the oxidizing solution to be supplied is not particularly limited as long as it can achieve the desired function, but for example, the weight of the oxidizing solution relative to the weight of the plastic material is 5 to 100 times, preferably 10 to 50 times. The supply rate of the oxidizing solution is not particularly limited as long as it can achieve the desired function, but for example, it is 50 to 500 cm ３ / min, and 80 to 200 cm ３ If the supply amount or supply rate is too small, it is difficult to obtain the desired effect, whereas if it is too large, there is a risk of damaging the equipment, materials, etc.

[0094] Regarding sterilization or disinfection, for example, used disposable diapers contain more than 1 billion bacteria per ml, but the acidic aqueous solution used up to the second separation step S3 cannot be said to be sufficient to completely kill all bacteria. Therefore, the plastic material separated in the second separation step S3 (with a small amount of pulp fiber or superabsorbent polymer attached) contains a certain amount of bacteria (e.g., 3,400 bacteria per ml). This can lead to concerns about adverse effects on worker safety and the decay and mold growth of the extracted plastic material. There is also a strong fecal odor thought to be caused by the bacteria. However, by performing the washing step S5 using an oxidizing aqueous solution, the bacteria in the plastic material can be removed below the detection limit, similar to E. coli, and the sulfur and nitrogen compounds can be decomposed to reduce the fecal odor to an almost undetectable level.

[0095] In this embodiment, an aqueous oxidizing solution is sprayed onto the plastic material as a cleaning liquid to remove sulfur compounds, nitrogen compounds, and other impurities derived from excrement remaining on the plastic material, but this embodiment is not limited to this. For example, a heated liquid (e.g., high-temperature water or steam, or superheated steam) may be sprayed onto the plastic material as a cleaning liquid to remove impurities such as sulfur compounds, nitrogen compounds, general bacteria, and E. coli derived from excrement remaining on the plastic material.

[0096] Alternatively, for example, heated gas (e.g., high-temperature (high-pressure) air) may be sprayed onto the plastic material as a cleaning gas instead of a cleaning liquid. In this case, examples of the apparatus and spraying method include a method in which a cleaning gas is used instead of a cleaning liquid in the apparatus for the cleaning step S5, and a method in which the plastic material is exposed to an atmosphere of the cleaning gas.

[0097] In these cases, impurities such as sulfur compounds, nitrogen compounds, general bacteria, and E. coli can be decomposed and / or stripped from the plastic material and removed from the plastic material. In these cases, since no oxidizing aqueous solution is used, it is safe and hygienic, and treatment costs can be reduced because no wastewater treatment such as an oxidizing aqueous solution is required.

[0098] Alternatively, depending on the amount of impurities in the plastic material, for example, it may not be necessary to perform a treatment such as the washing step S5 described above. In this case, for example, the plastic material may be simply washed with water, or may be left unwashed, and impurities remaining in the plastic material, such as sulfur compounds and nitrogen compounds derived from excrement, general bacteria, and E. coli, may be removed by a heat and pressure treatment in the compression, dehydration, and drying step S6 described below.

[0099] The squeezing, dehydrating, and drying step S6 is a step of squeezing, dehydrating, and drying the plastic material treated in the washing step S5. That is, in the squeezing, dehydrating, and drying step S6, multiple treated plastic materials are combined together and squeezed and dehydrated as a whole, while being heated and dried.

[0100] In this embodiment, in the compression, dehydration, and drying step S6, the plastic material processed in the washing step S5 is supplied to a compression, dehydration, and drying device. The compression, dehydration, and drying device compresses multiple plastic materials together while heating them, squeezing out the moisture, and dehydrating and drying them. Examples of heating temperatures include 80 to 160°C. Higher temperatures may carbonize pulp fibers that may be contained in the plastic materials, while lower temperatures may make it difficult to achieve the desired drying effect. The heating time varies depending on the heating temperature, but may be, for example, 5 seconds to 5 minutes, with 10 seconds to 3 minutes being preferred. If the heating time is longer, the drying effect will saturate, while if the heating time is shorter, the drying effect will be difficult to achieve. The compression pressure varies depending on the heating temperature and heating time, but may be, for example, 0.2 to 4 MPa, with 0.4 to 2 MPa being preferred. If the pressure is lower, the dehydration effect will be poor, while if the pressure is higher, the dehydration effect will saturate. The squeeze dehydration and drying device softens (and / or melts) the plastic material and extrudes it out through numerous holes (e.g., opening diameter: 5 to 15 mm), thereby forming the plastic material into flakes or pellets, which can be easily packaged.

[0101] This compression, dehydration, and drying step S6 also decomposes and / or separates impurities such as sulfur compounds, nitrogen compounds, general bacteria, and E. coli from the plastic material, and removes them from the plastic material. This step does not require additional steps such as wastewater treatment using an oxidizing aqueous solution, making it safe and hygienic, and reducing processing costs.

[0102] A plurality of plastic materials are combined, heated, compressed, and delivered by a compression, dehydration, and drying device. This squeezes out the water, evaporates the water, and produces a dehydrated, dried plastic material. This produces a reusable plastic material. The moisture content of the plastic material is 5% by mass or less, preferably 3% or less. The compression, dehydration, and drying may be performed in separate devices.

[0103] The dehydration and drying of the plastic material is not limited to the above-mentioned compression dehydration drying step S6, and a general dehydration and drying step may be performed if the shape of the plastic material is not to be changed. Examples of such dehydration and drying steps include drying the plastic material in a high-temperature atmosphere in a thermostatic chamber or with hot air. The drying temperature may be, for example, 80 to 120°C. The drying time may be, for example, 10 to 120 minutes, depending on the drying temperature.

[0104] In this way, the recycled plastic material is produced as one embodiment of the resin composition according to this embodiment.

[0105] The proportion of insoluble components in the plastic material (resin composition) can be adjusted, for example, by the second separation step S3 and the washing step S5. In the second separation step S3, for example, by suppressing the degree of separation of insoluble components such as pulp fibers and superabsorbent polymers, the proportion of insoluble components in the plastic material can be increased. In the washing step S5, for example, by suppressing the degree of washing away with the washing liquid, the proportion of insoluble components in the plastic material can be increased.

[0106] On the other hand, in this embodiment, the mixed liquid containing the pulp fibers, superabsorbent polymer, excrement, and acidic aqueous solution separated in the first separation step S2 is treated in the dust removal step S7 to the pulp fiber separation step S10. The regenerated (recycled) pulp fibers and superabsorbent polymer can then be used to adjust the composition of the resin composition. This will be explained in detail below.

[0107] In the dust removal step S7, a separator (e.g., a screen separator or a cyclone separator) is used to separate foreign matter, such as other materials (collection bags, films, nonwoven fabrics, elastic materials, etc.) that were not completely separated, from the mixed liquid supplied from the first separation step S2 (and the second separation step S3). In this embodiment, in the dust removal step S7, a screen separator (with a relatively large mesh size), a screen separator (with a relatively small mesh size), and a cyclone separator are arranged in this order, and foreign matter is sequentially separated from the mixed liquid. This results in a mixed liquid containing pulp fibers, superabsorbent polymers, excrement, and an acidic aqueous solution with little foreign matter. The mixed liquid is then supplied to the SAP separation step S8. Note that the dust removal step S7 can be omitted when it is not necessary to separate foreign matter from the mixed liquid (e.g., when the mixed liquid contains only a small amount of foreign matter and the foreign matter is separated in a later step).

[0108] In the SAP separation step S8, a separator (e.g., a drum screen separator) is used to separate the superabsorbent polymer from the mixture containing pulp fibers with little foreign matter, superabsorbent polymer, excrement, and an acidic aqueous solution, which is supplied from the dust removal step S7. In this embodiment, in the SAP separation step S8, the drum screen separator separates the superabsorbent polymer, excrement, and acidic aqueous solution from the mixture. This results in the superabsorbent polymer, excrement, and acidic aqueous solution. The mixture containing the superabsorbent polymer, excrement, and acidic aqueous solution is then separated into two separate separators (e.g., an inclined screen separator) to remove the excrement and acidic aqueous solution, and is then subjected to sterilization, washing, drying, etc. as necessary, and recovered as a superabsorbent polymer. Meanwhile, the pulp fibers (which contain a small amount of superabsorbent polymer) are supplied to the oxidizing agent treatment step S9.

[0109] In the oxidizing agent treatment step S9, the pulp fibers containing little impurities (but containing a small amount of superabsorbent polymer) supplied from the SAP separation step S8 are oxidatively decomposed and solubilized by an oxidizing agent aqueous solution to remove the superabsorbent polymer from the pulp fibers. In this embodiment, in the oxidizing agent treatment step S9, the pulp fibers are introduced into a treatment tank that stores an oxidizing agent aqueous solution containing ozone as an oxidizing agent, and the superabsorbent polymer in the pulp fibers is oxidatively decomposed and solubilized to obtain pulp fibers with extremely few impurities. The pulp fibers with few impurities (including superabsorbent polymer) are supplied to the pulp fiber separation step S10 together with the oxidizing agent aqueous solution.

[0110] The type of oxidizing agent used in the oxidizing agent treatment step S9 is the same as that used in the cleaning step S5. In this embodiment, ozone is used as the oxidizing agent from the viewpoint of oxidizing power, sterilizing power, and bleaching power. The ozone concentration in the oxidizing agent aqueous solution is not particularly limited as long as it is a concentration that can decompose the superabsorbent polymer, but can be, for example, 10 to 50 mass ppm. A concentration that is not too low can completely solubilize the superabsorbent polymer, and a concentration that is not too high can prevent damage to the pulp fibers. The treatment time with the oxidizing agent aqueous solution is not particularly limited as long as it is a time that can decompose the superabsorbent polymer, but is shorter when the ozone concentration in the oxidizing agent aqueous solution is high and longer when the ozone concentration is low, and is typically 5 to 300 minutes. The product of the ozone concentration (ppm) in the oxidizing agent aqueous solution and the treatment time (minutes) of the treatment step (hereinafter also referred to as the "CT value") is preferably 100 to 15,000 ppm·min. If the CT value is too small, the superabsorbent polymer may not be completely solubilized, and the superabsorbent polymer may remain in the pulp fibers. If the CT value is too large, the pulp fibers may be damaged.

[0111] In the pulp fiber separation step S10, a separator (e.g., a screen separator) is used to separate the pulp fibers from the pulp fibers and oxidant aqueous solution supplied in the oxidant treatment step S9. The pulp fibers separated and recovered in this manner become so-called recycled pulp fibers. The recycled pulp fibers are washed with wash water and extracted.

[0112] In the mixing step S11, at least one of the superabsorbent polymer extracted in the SAP separation step S8 and the pulp fiber extracted in the pulp fiber separation step S10 is added to the plastic material that has undergone the squeeze, dehydration, and drying step S6, as needed, to produce a resin composition having a desired ratio of soluble and insoluble components. In this embodiment, the insoluble components in the plastic material, i.e., the pulp fiber and superabsorbent polymer content (mass%), are first measured using the <Method for Measuring Soluble and Insoluble Components> described below. If the ratio of insoluble components is lower than the desired ratio, the insoluble components, i.e., the pulp fiber or superabsorbent polymer, are added to the plastic material. If the ratio of soluble and insoluble components is neither too high nor too low, the plastic material is used as a resin composition as is. Note that if the ratio of insoluble components is higher than the desired ratio, a separate plastic material that has been separated separately may be added to the plastic material that has undergone the squeeze, dehydration, and drying step S6.

[0113] In this way, a recycled plastic material whose composition is adjusted using recycled pulp fibers and a superabsorbent polymer (or another plastic material) is produced as another aspect of the resin composition according to this embodiment.

[0114] In the method for producing a resin composition derived from used sanitary products containing excrement according to this embodiment, a first fraction is separated in a first separation step S2. At this time, the superabsorbent polymer that absorbed urine and other substances is inactivated, releasing sodium and nitrogen compounds along with water (dehydration) to the outside and becoming granular. Therefore, in the second separation step, the superabsorbent polymer of the first fraction can be easily separated from the plastic material by physical impact. Furthermore, even if there is any superabsorbent polymer that cannot be completely separated from the plastic material, the sodium and nitrogen compound content of that superabsorbent polymer can be reduced. Furthermore, other excrement and pulp fibers can also be easily separated from the plastic material by physical impact.

[0115] Thereafter, the plastic material separated in the second separation step S3 is subjected to a washing step S5 (oxidizing agent treatment step). At this time, sulfur compounds and nitrogen compounds derived from excrement that were not completely separated in the second separation step S3 and remained in the plastic material are oxidized to other odorless substances (e.g., sulfur (S) and nitrogen (N)). ２ )), and some or all of the substances are mixed into the oxidizing aqueous solution and / or released as gas. That is, most of the sulfur and nitrogen compounds remaining in the plastic material are removed. In this way, odorous sulfur and nitrogen compounds are converted into other odorless substances and largely removed, making it less likely for the plastic material to produce a foul odor. The oxidizing agent can also be used to sterilize the plastic material. In this case, by supplying the oxidizing aqueous solution to the plastic material by spraying, the force of the spray can wash away sulfur and nitrogen compounds adhering to the surface of the plastic material. Furthermore, by finely splitting the oxidizing aqueous solution by spraying and supplying it to the plastic material, the oxidizing aqueous solution can more easily penetrate into the fine details of the plastic material. Furthermore, compared to immersing the plastic material in the oxidizing aqueous solution, a fresh oxidizing aqueous solution can be constantly supplied to the surface of the plastic material, reducing variation in the cleaning and sterilization effects.

[0116] In this way, impurities including sodium, sulfur, and nitrogen are separated and removed from the plastic material produced by this method, thereby suppressing impurities in the plastic material. Sterilization can also be performed at the same time. Furthermore, when the plastic material is subjected to material recycling or chemical recycling to produce recycled products, the suppression of impurities in the plastic material reduces the impact on catalysts used in the manufacturing process and reduces the likelihood of generating undesirable odors.

[0117] In a preferred embodiment of the method for producing the resin composition, the second separation step S3 includes spraying an acidic aqueous solution onto the first fraction while applying physical impact to separate the excrement, superabsorbent polymer, and pulp fibers from the plastic material. Thus, in this method, the first fraction is sprayed with an acidic aqueous solution in the second separation step S3. Therefore, the superabsorbent polymer remaining in the plastic material is further inactivated by the acidic aqueous solution, further releasing sodium and nitrogen compounds (dehydration) to the outside, resulting in finer particles. Therefore, the superabsorbent polymer can be more easily separated from the plastic material by physical impact or the flow of the acidic aqueous solution. Furthermore, even if there is any superabsorbent polymer that cannot be completely separated from the plastic material, the sodium and nitrogen compound content of the superabsorbent polymer can be further reduced. Furthermore, other excrement and pulp fibers can also be more easily separated from the plastic material by physical impact or the flow of the acidic aqueous solution.

[0118] In a preferred embodiment, the method for producing the resin composition further includes a squeeze-dehydration-drying step S6 in which the plastic material treated in the washing step S5 is squeezed, dehydrated, and dried. That is, the plastic material treated in the washing step S5 is squeezed, dehydrated, and dried, so that the moisture content in the plastic material can be further reduced. This allows impurities (e.g., substances containing sulfur or nitrogen that do not produce a bad odor) that have become mixed in the moisture (aqueous solution) in the washing step S5 or the like to be removed from the plastic material together with the moisture.

[0119] <Method for Measuring Soluble and Insoluble Components> The soluble and insoluble components in a resin composition are measured as follows. (1) First, for each of the soluble and insoluble components in a resin composition, component separation is performed by utilizing the difference in solubility of the components in various solvents. Specifically, the method is as follows. First, a sample of the resin composition to be measured is dissolved and dispersed in tetrahydrofuran (THF), and then filtered and separated (using a 5 μm filter) to separate the solvent-soluble and solvent-insoluble components. The solvent-soluble components in THF are centrifuged (12,000 rpm x 0.5 h) to separate them into a solvent-insoluble component (F11) and a solvent-soluble component. The solvent-soluble components after centrifugation are dissolved and dispersed in methanol, and then filtered and separated (using a 3 μm filter) to separate them into a solvent-insoluble component (F12) and a solvent-soluble component (F13). The solvent-insoluble components of THF are dissolved and dispersed in hexafluoroisopropanol (HFIP), and then filtered (using a 5 μm filter) to separate them into solvent-soluble and solvent-insoluble components. The solvent-soluble components of HFIP are dissolved and dispersed in methanol, and then filtered (using a 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 in heated xylene, and then filtered (using a 200 mesh filter) to separate them into solvent-soluble and solvent-insoluble components (F31). The solvent-soluble components of xylene are dissolved and dispersed in methanol, and then filtered (using a 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) For the mixture of fraction F12 and fraction F13, １ (4) Fraction F32 was analyzed by high temperature NMR. １３ (5) Fraction F31 is carbonized in an electric furnace (570°C, 2 hours), and the residue is taken as ash, and the weight loss is taken as pulp fiber. (6) Based on the results of (2) to (5) above, the ratios of soluble and insoluble components and qualitative results are determined.

[0120] <Method for measuring sound absorption> The method for measuring the sound absorption of a sound-absorbing material using a resin composition is as follows. (1) The measurement conditions are as follows. Measurement frequency: 100 to 5000 Hz (1 / 3 octave band) Sound source: Broadband noise (pink noise) in the 100 to 5000 Hz band Sound receiving position: Three points (microphone height: 1.2 m, 1.35 m, and 1.5 m above the floor) (At least 1 m away from the test specimen and wall in a straight line) Number of measurements: Three times at each sound receiving point Test specimen placement i) The long side of the test specimen (approximately 3 kg / bag) is parallel to the long side of the test specimen laying area, and the specimen is placed towards the north side of the area Number of test specimens: 35 bags (9.42 m ２ ), Temperature and humidity during testing: 10 ° C, 71% ii) The long side of the test specimen (approximately 4 kg / bag) is parallel to the long side of the test specimen laying area, and placed on the south side of the area Number of test specimens: 35 bags (9.42 m ２ ), Temperature and humidity during testing: 10°C, 72% iii) The long side of the test specimen (approximately 4 kg / bag) is perpendicular to the long side of the test specimen laying area, and placed on the north side of the area Number of test specimens: 36 bags (9.515 m ２ ), Temperature and humidity during testing: 10°C, 71% This measurement method complies with JIS-A-1409 (Method for measuring sound absorption coefficient in a reverberation room), the reverberation room has an abbreviated rectangular floor shape, the test specimen area is a rectangular area spaced apart from each wall in the center of the reverberation room, and the speaker is located on the east side of the test specimen area. (2) Measurements are taken for test specimen arrangements (i) to (iii), and the average is taken as the final measurement value.

[0121] <Method for measuring sulfur, nitrogen, aluminum, and chlorine contents> The method for measuring the sulfur, nitrogen, aluminum, and chlorine contents (mass%) of a resin composition and a solid fuel is as follows. (1) An energy dispersive X-ray analyzer (EDX: Shimadzu EDX-7200) is prepared. (2) The resin composition or solid fuel to be measured is dried (120°C x 60 minutes), and a sample is taken from the dried resin composition or solid fuel in an amount that can be placed on the sample stage of the analyzer and is sufficient for measurement, and the sample is fixed to the sample stage. (3) The sulfur, nitrogen, aluminum, and chlorine contents in the sample are measured using the analyzer. (4) The measurement results of five samples are averaged to determine the final sulfur, nitrogen, sodium, and chlorine contents in the resin composition.

[0122] <Method for measuring higher heating value, and mass fraction of moisture and ash> The higher heating value (MJ / kg) of the resin composition and solid fuel to be measured is determined by a method conforming to JIS Z 7302-2. The mass fraction (%) of moisture of the resin composition and solid fuel to be measured is determined by a method conforming to JIS Z 7302-3. The mass fraction (%) of ash of the resin composition and solid fuel to be measured is determined by a method conforming to JIS Z 7302-4.

[0123] <Method for Measuring Bulk Gravity> The bulk gravity of a resin composition or solid fuel is determined as follows. First, a container of a fixed volume (e.g., 1 L) is filled with the resin composition or solid fuel to be measured, and the total mass of the resin composition or solid fuel is measured. The bulk gravity of the resin composition or solid fuel to be measured is then determined by dividing the measured mass by the mass of water equal to the volume of the container.

[0124] <Method for Measuring E. coli> The method for measuring E. coli in resin compositions and solid fuels is as follows. (1) In a 1-liter beaker, 500 g of an aqueous dispersion of the resin composition or solid fuel to be tested, with a solid content concentration of 5.0% by mass, is prepared. - When the resin composition or solid fuel exists in a dry state: The aqueous dispersion can be formed by mixing the resin composition or solid fuel (25.0 g in terms of solid content) with deionized water (a total amount of 500.0 g). - When the resin composition or solid fuel exists in an aqueous solution (for example, when the resin composition or solid fuel is recovered as an aqueous solution in a method for producing a resin composition or solid fuel), and the solid content concentration of the resin composition or solid fuel is 5.0% by mass or more: An aqueous dispersion of the resin composition or solid fuel with a solid content concentration of 5.0% by mass can be prepared by adding deionized water to the aqueous solution. - When the resin composition or solid fuel is present as an aqueous solution and the solid content concentration of the resin composition or solid fuel is less than 5.0% by mass, the solid content concentration of the resin composition or solid fuel can be adjusted to 5.0% by mass by filtration, or the aqueous solution itself can be used as an aqueous dispersion and the inoculation amount of the serially diluted sample described below can be increased (for example, if the solid content concentration of the resin composition or solid fuel is 2.5% by mass, the inoculation amount can be doubled). (2) The aqueous dispersion is stirred for 15 minutes at a rotation speed of 300 rpm using an overhead stirrer. (3) 50 mL of the aqueous dispersion stirred using an overhead stirrer is placed in a sterilized bag with a filter (manufactured by LMS, sterilized bag with filter for homogenizer) and stirred for 5 minutes. (4) The aqueous dispersion after filtering through the sterilized bag with a filter is dispensed into sterilized test tubes and 10 －９ The diluted sample is serially diluted 10-fold to 100 ml, and dispensed into sterilized test tubes to prepare serially diluted samples. (5) The number of E. coli bacteria is measured by the pour culture method. Specifically, 1 mL of the serially diluted sample and 15 to 20 g of standard agar medium (Shiotani MS Co., Ltd., 399-02201 EMB agar medium "Daigo" for E. coli testing, pour culture is performed at 35°C for 48 hours. (6) The number of E. coli bacteria is determined by counting the number of colonies that have grown after culture. Note that, －９If the colony count is zero in all serially diluted samples up to 10 times, the target bacteria is determined to be "not detected," i.e., the viable bacterial count detected by the pour plate culture method is below the detection limit. In other words, the viable bacterial count is 0 cfu / g. (7) If colonies of enterobacteria or viable bacteria are formed after culture, the type of bacteria can be identified. Identification can be performed by biochemical property testing.

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

[0126] (1) Samples Example 1: The resin composition of Example 1 was obtained by carrying out the crushing step S1 to the compression dehydration drying step S6 of the method for producing a resin composition derived from used sanitary products containing excrement, according to the present embodiment, using used disposable diapers containing excrement as a raw material. However, the acidic aqueous solution in the second separation step S3 was a 0.1% by mass aqueous sulfuric acid solution, and the cleaning solution in the cleaning step S5 was water. Example 2: The sound-absorbing material of Example 2 was formed using the resin composition of Example 1. However, the sound-absorbing material was produced by packing 4 kg of the resin composition into a polyethylene resin bag measuring 570 mm x 440 mm x 50 mm. 36 bags of such sound-absorbing material were produced. Example 3: The solid fuel of Example 3 was formed by extrusion molding using the resin composition of Example 1 (10 kg / cm ２ , 150°C, 10 minutes).

[0127] (2) Evaluation Methods (a) Composition of Resin Composition The resin composition of Example 1 was measured for soluble and insoluble components by the above-mentioned <Method for measuring soluble and insoluble components>. (b) Sound Absorption of Sound Absorbing Materials The sound absorption of the following sound absorbing materials was measured by the above-mentioned <Method for measuring sound absorption>. - Sound absorbing material of Example 2 - Commercially available glass wool 24K (1 m ２(Comparative Example 1) Commercially available 24K glass wool - sound absorbing material, 25 mm thick (Comparative Example 2) Commercially available rock wool sound absorbing board - thickness 12 mm (Comparative Example 3) (c) Composition of solid fuel, etc. For the resin composition of Example 1 and the solid fuel of Example 3, the higher heating value, mass fraction of moisture and ash, contents of sulfur, chlorine, nitrogen and aluminum, bulk specific gravity composition, and E. coli were measured using the above-mentioned <Method for measuring higher heating value, and mass fraction of moisture and ash>, <Method for measuring sulfur, nitrogen, aluminum and chlorine contents>, <Method for measuring bulk specific gravity>, and <Method for measuring E. coli>.

[0128] (3) Evaluation Results (a) Composition of Resin Composition The results of measurements on the composition of the resin composition of Example 1 are shown in Table 1 below. In the resin composition of Example 1, the soluble components of the polyolefin resins, polypropylene and polyethylene, were 46.2% by mass and 17.0% by mass, respectively. The soluble component of the polyester resin, polyethylene terephthalate, was 9.1% by mass. The soluble component of the styrene-containing polymer (styrene) was 1.9% by mass. The soluble component of hydrocarbons, which may contain polyurethane, was 8.2% by mass. Other soluble components, butadiene, oligomers, and additives, were 0.9% by mass and 0.3% by mass, respectively. Meanwhile, the insoluble components, pulp fiber (cellulose) and inorganic compound (calcium carbonate), were 14.7% by mass and 1.7% by mass, respectively. Therefore, the soluble component was 83.6% by mass, and the insoluble component was 16.4% by mass. The proportion of polyolefin resin in the soluble component was 75.6% by mass. The proportion of pulp fiber (cellulose) and inorganic compound (calcium carbonate) in the insoluble components was approximately 100% by mass. As will be described later, the resin composition of Example 1 had extremely low contents of sulfur, chlorine, nitrogen, and aluminum, and no E. coli was detected.

[0129]

[0130] (b) Sound absorption of sound-absorbing material The measurement results of the sound absorption of the sound-absorbing material of Example 2 are shown in Figure 2. In the graph of the figure, the vertical axis represents the reverberation chamber sound absorption coefficient, and the horizontal axis represents the 1 / 3 octave band center frequency (Hz). However, circles represent the results of Example 2, crosses represent the results of Comparative Example 1 (glass wool 24K - thickness 50 mm), diamonds represent the results of Comparative Example 2 (glass wool 24K - thickness 25 mm), and triangles represent the results of Comparative Example 3 (rock wool board - thickness 12 mm). From the graph, it can be seen that the sound-absorbing material of Example 2 exhibited a higher sound absorption coefficient than the rock wool board of Comparative Example 3, and at frequencies higher than 1000 Hz, it exhibited characteristics equal to or better than the glass wool of Comparative Examples 1 and 2.

[0131] (c) Composition, etc. of Solid Fuel The results of measurements on the composition, etc. of the resin composition of Example 1 and the solid fuel of Example 3 are shown in Table 2 below. The resin composition of Example 1 had an extremely high higher heating value of 39.1 MJ / kg, and extremely low contents of moisture, ash, sulfur, chlorine, nitrogen, and aluminum of 0.7 mass%, 2.68 mass%, 0.022 mass%, 0.020 mass%, less than 0.30 mass%, and less than 0.10 mass%, respectively, and no E. coli was detected. The bulk specific gravity was a slightly low 0.199. Therefore, except for the bulk specific gravity, the solid fuel of Example 3 had properties that conformed not only to Grade A RPF in the quality standard for RPF (Refuse-derived paper and plastics densified fuel) (JIS Z7311:2010 "Solidified fuel (RPF) from waste materials such as paper and plastics" (RPF)), but also to RPF-coke. The solid fuel of Example 3 had an extremely high higher heating value of 36.5 MJ / kg, and extremely low moisture, ash, sulfur, chlorine, nitrogen, and aluminum contents of 0.7% by mass, 2.08% by mass, 0.015% by mass, 0.039% by mass, less than 0.30% by mass, and less than 0.10% by mass, respectively, and no E. coli was detected. The bulk specific gravity was 0.392. Therefore, it had properties that met not only grade A of the RPF variety in the RPF quality standards, but also the RPF-coke variety.

[0132]

[0133] The resin composition of the present invention and the product using the same are not limited to the above-described embodiments, and suitable combinations and modifications can be made within the scope of the object and spirit of the present invention.

[0134] S1 Crushing process S2 First separation process S3 Second separation process S4 Air conveying process S5 Washing process S6 Compression dehydration drying process S7 Dust removal process S8 SAP separation process S9 Oxidizing agent treatment process S10 Pulp fiber separation process S11 Mixing process

Claims

1. A resin composition derived from used sanitary products containing excreta, comprising a soluble component and an insoluble component, wherein the proportion of the soluble component is 80 to 90% by mass, the proportion of the insoluble component is 10 to 19% by mass, and the proportion of nitrogen atoms contained in the resin composition is less than 0.5% by mass.

2. The resin composition according to claim 1, wherein the soluble component contains a polyolefin resin as a main component.

3. The resin composition according to claim 1 or 2, wherein the soluble component further contains a polyester resin.

4. The resin composition according to claim 3, wherein the polyester resin contains polyethylene terephthalate.

5. The resin composition according to any one of claims 1 to 4, wherein the soluble component further contains at least one of polyurethane and a styrene-containing polymer.

6. The resin composition according to any one of claims 1 to 5, wherein the insoluble component contains at least one of cellulose fibers, a superabsorbent polymer, and an inorganic compound.

7. The resin composition according to any one of claims 1 to 6, wherein the proportion of ash contained in the resin composition is less than 4% by mass.

8. The resin composition according to any one of claims 1 to 7, wherein the proportion of chlorine atoms contained in the resin composition is less than 0.1% by mass.

9. The resin composition according to any one of claims 1 to 8, wherein Escherichia coli contained in the resin composition is below the detection limit.

10. The resin composition according to any one of claims 1 to 9, wherein the proportion of sulfur atoms contained in the resin composition is less than 0.1% by mass.

11. A sound-absorbing material comprising the resin composition according to any one of claims 1 to 10.

12. A solid fuel comprising the resin composition according to any one of claims 1 to 10 and having a bulk specific gravity of 0.3 to 0.

5.

13. A container comprising the resin composition according to any one of claims 1 to 10.

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