Resin molded article

Abstract

A resin molded article contains a resin derived from a used paper diaper. The resin molded article may contain a pulp component, and the content of the pulp component is 0.1 parts by mass or more with respect to 100 parts by mass of the resin.

Description

Technical Field

[0001] The present invention relates to a resin molded product.

[0002] This application claims priority based on Japanese Patent Application No. 2022-066968 filed in Japan on April 14, 2022, and the contents are incorporated herein by reference. Background Art

[0003] There is a trend to collect and reuse constituent materials of paper diapers from used paper diapers.

[0004] For example, Patent Document 1 proposes a method for recycling materials of used disposable diapers, which is characterized in that a water-absorbing polymer contained in the disposable diaper is decomposed into monomers and then a pulp component contained in the disposable diaper is separated and recovered.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 3378204 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, the method used in Patent Document 1 is a technique for recycling pulp components and other components separately, and further efficiency in recycling of materials is required.

[0010] Therefore, an object of the present invention is to provide a resin molded product capable of more effectively utilizing the material of used disposable diapers.

[0011] Means for solving problems

[0012] The present invention has the following aspects.

[0013] [1] A resin molded product comprising a resin derived from used paper diapers.

[0014] [2] In the above [1], the resin molded article may contain a pulp component, wherein the content of the pulp component is 0.1 parts by mass or more relative to 100 parts by mass of the resin.

[0015] [3] In the above [1] or [2], the resin molded article may contain a water-absorbing material, wherein the content of the water-absorbing material is 0.1 parts by mass or more relative to 100 parts by mass of the resin.

[0016] [4] In any one of the above [1] to [3], the resin molded article may contain a calcium compound, wherein the content of the calcium compound is 0.1 parts by mass or more relative to 100 parts by mass of the resin.

[0017] [5] In any one of the above [1] to [4], the resin molded article may contain a coloring material, wherein the content of the coloring material is 0.1 to 70 parts by mass based on 100 parts by mass of the resin.

[0018] [6] In any one of the above [1] to [5], the resin molded article may be an inflation film

[0019] (inflation film).

[0020] [7] In any one of the above [1] to [5], the resin molded product may be an injection molded product.

[0021] [8] In any one of the above [1] to [7], the resin molded article may have a decorative layer on its surface.

[0022] Effects of the Invention

[0023] According to the resin molded article of the above aspect, the material of the used disposable diapers can be effectively utilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] [ Figure 1 ] is a block diagram showing the process of a method for manufacturing a resin molded product involved in one embodiment of the present invention. DETAILED DESCRIPTION

[0025] [Resin molded products]

[0026] In this specification, "resin molded product" includes resin as an essential component. As the resin, resins commonly used in disposable diapers can be listed, for example, polyethylene, polypropylene, polystyrene, polyester, etc. As polyester, for example, polyethylene terephthalate, etc. can be listed. These resins can be used alone or in combination of two or more.

[0027] The resin molded product of the present disclosure contains a resin derived from a used disposable diaper. That is, in the present disclosure, part or all of the resin as an essential component is derived from a used disposable diaper.

[0028] The content of the resin derived from used diapers is, for example, preferably 10% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more relative to the total mass of the resin molded product. When the content of the resin derived from used diapers is equal to or more than the above lower limit, the material of the used diapers can be more effectively utilized. The upper limit of the content of the resin derived from used diapers is not particularly limited, and is, for example, 99% by mass.

[0029] The content of the resin in the resin molded product is determined by, for example, nuclear magnetic resonance (NMR) method, and the content of the resin from the used disposable diaper is determined by subtracting the content of the resin added when forming the resin molded product from the content of the resin in the resin molded product.

[0030] From the viewpoint of further improving the quality of the resin molded product, the resin molded product may contain resins other than the resin from the used diapers (hereinafter also referred to as "added resin"). As the added resin, for example, general-purpose resins such as polyethylene, polypropylene, polystyrene, and polyethylene terephthalate can be listed. Among these added resins, polyethylene and polypropylene are preferred, and polyethylene is more preferred, from the viewpoint of easily improving the quality of the resin molded product. As polyethylene, for example, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), etc. can be listed. As polypropylene, for example, stretched polypropylene (OPP), unstretched polypropylene (CPP), etc. can be listed.

[0031] The content of the added resin is preferably 70% by mass or less, more preferably 50% by mass or less, further preferably 10% by mass or less, and may be 0% by mass, relative to the total mass of the resin molded product. When the content of the added resin is below the upper limit, the material of the used disposable diaper can be more effectively utilized.

[0032] The content of the added resin can be adjusted by the amount of the resin added when forming the resin molded article, and can be appropriately adjusted according to the physical properties required for the resin molded article.

[0033] The used disposable diapers of the present embodiment may contain excrement such as urine and feces, and may include disposable diapers that have been discarded as they are without being used.

[0034] When reusing used diapers, the used diapers are washed and then immersed in an aqueous solution containing a calcium compound to release the water such as urine contained in the water-absorbing material. Thereafter, the diapers are disinfected and dried to separate the resin component.

[0035] Therefore, the resin molded product of the present embodiment may contain a water-absorbing material or a calcium compound in addition to the pulp component contained in the disposable diaper.

[0036] Examples of the pulp component include pulp and synthetic fibers used in nonwoven fabrics of disposable diapers.

[0037] The content of the pulp component is preferably 70% by mass or less, more preferably 50% by mass or less, and further preferably 10% by mass or less, relative to 100 parts by mass of the resin from used diapers. When the content of the pulp component is below the upper limit, the quality of the resin molded product can be ensured. The lower limit of the content of the pulp component is not particularly limited, but from the viewpoint of easily confirming that the resin molded product is made of diapers as a raw material, for example, it is set to 0.1 parts by mass relative to 100 parts by mass of the resin from used diapers.

[0038] The content of the pulp component can be determined by, for example, component sugar analysis.

[0039] Examples of the water-absorbing material include super absorbent polymers (SAP) and the like.

[0040] Examples of the highly water-absorbent polymer include sodium polyacrylate, carboxymethylcellulose, and polyvinyl alcohol. Of these highly water-absorbent polymers, sodium polyacrylate is preferred because it is widely available.

[0041] The content of the water-absorbing material is preferably 70 parts by mass or less, more preferably 50 parts by mass or less, and further preferably 10 parts by mass or less, relative to 100 parts by mass of the resin from the used diaper. When the content of the water-absorbing material is below the upper limit, the quality of the resin molded product can be ensured. The lower limit of the content of the water-absorbing material is not particularly limited, but from the viewpoint of easily confirming that the resin molded product is made of diapers as a raw material, for example, it is set to 0.1 parts by mass relative to 100 parts by mass of the resin from the used diaper.

[0042] The content of the water-absorbing material can be determined by, for example, the NMR method or the time-of-flight secondary ion mass spectrometry (TOF-SIMS) method.

[0043] In this specification, water-absorbing materials are not included in the above-mentioned "resins derived from used paper diapers" and "added resins".

[0044] Examples of the calcium compound include calcium chloride, calcium oxide (quicklime), calcium hydroxide (slaked lime), etc. As for the calcium compound, calcium chloride is preferred as the calcium compound because it can be widely used as a dehydrating material.

[0045] The content of the calcium compound is, for example, preferably 70 parts by mass or less, more preferably 50 parts by mass or less, and further preferably 10 parts by mass or less, relative to 100 parts by mass of the resin from the used diaper. When the content of the calcium compound is below the above upper limit, the quality of the resin molded product can be ensured. The lower limit of the content of the calcium compound is not particularly limited, but from the viewpoint of easily confirming that the resin molded product is made of used diapers as a raw material, for example, it is set to 0.1 parts by mass relative to 100 parts by mass of the resin from the used diaper.

[0046] The content of the calcium compound can be determined by, for example, X-ray diffraction (XRD) or X-ray photoelectron spectroscopy (XPS).

[0047] From the viewpoint of having a good appearance, the resin molded article may contain a coloring material such as a pigment or a dye.

[0048] The content of the coloring material is preferably 0.1 to 70 parts by mass, more preferably 1 to 50 parts by mass, and even more preferably 5 to 30 parts by mass relative to 100 parts by mass of the resin from the used diaper. When the content of the coloring material is above the lower limit, the resin molded product can have a better appearance. When the content of the coloring material is below the upper limit, the physical properties of the resin molded product can be further improved.

[0049] The content of the coloring material can be determined by, for example, the NMR method or the TOF-SIMS method.

[0050] From the viewpoint of having a good appearance, the resin molded article may have a decorative layer on the surface.

[0051] Examples of the decorative layer include a printed layer having a surface printed thereon and a decorative layer having a surface decorated thereon.

[0052] The form of the resin molded product is not particularly limited, and examples thereof include inflation films obtained by inflation molding, pellets obtained by granulation, injection molded bodies (injection molded products) obtained by injection molding, and sheet molded bodies obtained by sheet molding.

[0053] Resin molded products can be used for various purposes, for example, packaging bags made by making inflation films; playground building blocks, flower bed fences, and roof parts made by injection molding; building material sheets and agricultural cover sheets made by extrusion molding.

[0054] [Manufacturing method of resin molded product]

[0055] The resin molded product of the present disclosure can be produced in the same manner as conventionally known resin molded products, except that used disposable diapers are used as raw materials.

[0056] Hereinafter, a method for producing a resin molded product according to the present embodiment will be described in detail with reference to the drawings.

[0057] like Figure 1 As shown, the method 1 for manufacturing a resin molded product according to the present embodiment includes a grinding step 20 , a foreign matter removing step 30 , a hot cutting step 40 , a pulverizing step 50 , and a molding step 60 .

[0058] Examples of the raw material 10 include resin components separated from used disposable diapers.

[0059] The paper diaper of this embodiment is composed of, for example, a surface material, leakproof three-dimensional gatherings, a water-absorbing material, a waterproof material, etc. The surface material may be a nonwoven fabric made of polyethylene or polypropylene, etc. The leakproof three-dimensional gatherings may be a composite of a nonwoven fabric and a stretchable material, etc.

[0060] Examples of water-absorbing materials include absorbent paper, pulp, and composites of polymer absorbents. Examples of waterproof materials include nonwoven fabrics made of synthetic fibers that cover the outside of the diaper. In addition, diapers may also have adhesive tapes, fixing materials, and other components that fasten the diaper.

[0061] When the used diapers are reused, the used diapers are washed and then immersed in an aqueous solution containing a calcium compound to release the water such as urine contained in the water-absorbing material. Then, the diapers are sterilized and dried to separate the resin component, thereby obtaining the raw material 10.

[0062] The grinding step 20 is a step of rotating the raw material 10 to reduce the volume (compress) the raw material 10 by utilizing the friction heat and shear heat generated during the rotation.

[0063] The manufacturing method of the resin molded product of this embodiment can obtain a reduced volume product (grush) in which the resin component is reduced in volume by having a grinding step 20. Since the resin component is not melted, the grush is less degraded and can be effectively mixed and blended. Therefore, in the subsequent foreign matter removal step 30, a large amount of grush can be processed.

[0064] In the grinding step 20 , a device such as a hopper that rotates while shearing the raw material 10 can be used.

[0065] The foreign matter removing step 30 is a step of heating the ground material to melt it and remove the foreign matter.

[0066] The hot cutting step 40 is a step of extruding and cutting the melt from which foreign matter has been removed.

[0067] The cut molten material is cooled to obtain a solidified product (hot-cut product) of the desired size.

[0068] An additional resin, a coloring material, etc. are added to the solidified product obtained in the heat cutting step 40 , kneaded, and cooled to obtain a resin molded product (molding step 60 ).

[0069] In the molding step 60, for example, various additives may be added in addition to the additive resin and coloring material added according to the desired quality of the resin molded product. By adding various additives, the functions possessed by the various additives may be imparted to the resin molded product.

[0070] Examples of the various additives include antioxidant materials, ultraviolet light absorbing materials, antibacterial materials, deodorizing materials, softening materials, and biodegradable materials.

[0071] The amount of each additive added is, for example, preferably 0.1 to 70 parts by mass, more preferably 1 to 50 parts by mass, and even more preferably 5 to 30 parts by mass relative to 100 parts by mass of the hot-cut product.

[0072] When the amount of each additive is greater than or equal to the lower limit, the functions of the additive can be imparted to the resin molded product. When the amount of each additive is less than or equal to the upper limit, the strength of the resin molded product can be ensured.

[0073] When the resin molded product has a decorative layer, there is no particular limitation on the method for providing the decorative layer, and examples thereof include: a method in which an adhesive material is applied to the surface of the molded body, the decorative layer is stacked, and the decorative layer is provided by curing the adhesive material; a method in which the decorative layer is provided by integrally molding the decorative layer with the molded body by extrusion molding, etc.

[0074] As mentioned above, the resin molded product of the present disclosure has been described in detail with reference to the drawings, but the specific configuration is not limited to the embodiments, and changes and combinations of the configurations are also included within the scope that does not depart from the gist of the present disclosure.

[0075] For example, part of the resin component of used disposable diapers may be used as the raw material, or all of it may be used as the raw material.

[0076] For example, various additives may be added in the hot cutting step 40 and then the melt may be cut and granulated.

[0077] For example, by imparting biodegradability to a resin molded product, a process for disposing of the resin molded product can be omitted, thereby reducing the load on the global environment.

[0078] Since the resin molded product of the present disclosure uses the resin component of used diapers as raw materials, the materials of used diapers that have been discarded can be more effectively utilized. Therefore, the amount of used diapers discarded can be reduced, thereby reducing the load on the global environment.

[0079] The resin molded product disclosed in the present invention can be circulated as a new product on the market even if the materials of the disposable diaper are not separated 100% for each material. Therefore, the precision in the separation process that has been required to separate with high precision can be reduced, and the resin molded product can be produced more easily.

[0080] The resin molded product disclosed in the present invention can be used as a raw material for further recycling, thereby reducing the waste of resources caused by disposal and the like, and reducing the load on the global environment.

[0081] Industrial Applicability

[0082] According to the resin molded article of the above-described embodiment, the material of the used disposable diapers can be effectively utilized.

[0083] Explanation of symbols

[0084] 1. Manufacturing method of resin molded product

[0085] 10. Raw Materials

[0086] 20 Grinding process

[0087] 30 Foreign matter removal process

[0088] 40 Hot cutting process

[0089] 60 Forming process

Claims

1. A resin molded product comprising a resin derived from used paper diapers. 2 . The resin molded product according to claim 1 , comprising a pulp component, wherein the content of the pulp component is 0.1 parts by mass or more relative to 100 parts by mass of the resin. 3 . The resin molded article according to claim 1 , comprising a water absorbing material, wherein the content of the water absorbing material is 0.1 parts by mass or more relative to 100 parts by mass of the resin. 4 . The resin molded article according to claim 1 , comprising a calcium compound, wherein the content of the calcium compound is 0.1 parts by mass or more relative to 100 parts by mass of the resin. 5 . The resin molded article according to claim 1 , comprising a coloring material, wherein the content of the coloring material is 0.1 to 70 parts by mass based on 100 parts by mass of the resin. The resin molded article according to claim 1 or 2, which is an inflation film.

7. The resin molded product according to claim 1 or 2, which is an injection molded product.

8. The resin molded article according to claim 1 or 2, which has a decorative layer on the surface.

Images