Method for producing resin composition molded article

Abstract

A method for producing a molded article of a resin composition according to the present disclosure comprises: preparing plastic waste containing a low-melting-point resin having a melting point in the range of 80 DEG C or more and less than 190 DEG C and a non-low-melting-point resin, which is a high-melting-point resin or a thermosetting resin having a melting point of 190 DEG C or more; the plastic waste is pulverized to obtain a resin composition powder, and the resin composition powder is mixed with a powder containing a low-melting-point resin and / or a powder containing a non-low-melting-point resin prepared in advance. A resin composition powder mixture in which the ratio of the content of the low-melting-point resin to the content of the non-low-melting-point resin is adjusted to a predetermined range is obtained, and the resin composition powder mixture is molded to obtain a resin composition molded article.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a molded resin composition. Background Technology

[0002] Wood-based resin compositions containing wood flour or other cellulose-based material powders dispersed in the resin are also known as wood plastics. While possessing a texture similar to wood, they offer advantages over wood, such as resistance to corrosion, cracking, and burrs, and are lightweight. Therefore, wood-based resin compositions are widely used in building materials and other applications. Research is underway to utilize low-melting-point resins such as polypropylene derived from waste materials as resins for wood-based resin compositions (see, for example, Patent Document 1 and Non-Patent Document 1).

[0003] As a resin raw material for resin composition molding articles, the use of plastic waste containing waste plastics is being investigated. For example, a method for manufacturing resin composition molding articles containing slag is being investigated, using high-melting-point plastics and low-melting-point plastics obtained from sorting two or more different types of plastic wastes (Patent Document 2). In addition, a molding article obtained by mixing and molding a pulverized mixture of plastic wastes with a plastic binder is being investigated.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2001-353707

[0005] Patent Document 2: Korean Patent Publication No. 10-2022-0002779

[0006] Patent Document 3: Japanese Patent Application Publication No. 7-227849

[0007] Non-patent literature

[0008] Non-Patent Document 1: Material Flow Diagram of the Production, Waste, Recycling, and Disposal of Plastic Products in 2020, China Plastics Recycling Association, https: / / www.pwmi.or.jp / flow_pdf / flow2020.pdf Summary of the Invention

[0009] From the viewpoint of promoting resource recycling and greatly contributing to reducing CO2 emissions from waste incineration, it is preferable to use plastic waste containing waste plastics as the resin raw material for resin composition moldings. However, conventionally, only easily thermoforming low-melting-point resins are separated and recycled from plastic waste for use. Since the separated and recycled low-melting-point resins can be thermoformed, they are used as recycled resins for material recycling. On the other hand, after separating and recycling low-melting-point resins, the remaining waste plastic residue contains an increased proportion of high-melting-point resins and thermosetting resins, i.e., non-low-melting-point resins, making thermoforming difficult. Therefore, it is difficult to utilize waste plastic residues other than through thermal recovery. As a result, the material recycling rate of plastic waste in Japan is low. In recent years, the urgent expectation to improve the material recycling rate of plastic waste has gradually increased. However, according to the research of the inventors, the ratio of low-melting-point resins to non-low-melting-point resins contained in plastic waste varies depending on the location and time of plastic waste generation. If the ratio of low-melting-point resins to non-low-melting-point resins contained in plastic waste is different, it is difficult to stably manufacture resin composition moldings by thermoforming. However, the process of separating plastic waste into low-melting-point resins and non-low-melting-point resins is cumbersome and requires specialized equipment for the separation.

[0010] The purpose of this disclosure is to provide a method for manufacturing a molded resin composition, which can be effectively utilized as a molding raw material even if the mixing ratio of resin (low-melting-point resin and non-low-melting-point resin) is different, without separating plastic waste containing low-melting-point resin and non-low-melting-point resin into low-melting-point resin and non-low-melting-point resin.

[0011] This disclosure relates to a method for manufacturing a resin composition molded article, comprising: preparing plastic waste comprising a low-melting-point resin having a melting point in the range of 80°C or higher and less than 190°C, and a non-low-melting-point resin having a melting point of 190°C or higher, or a thermosetting resin; pulverizing the plastic waste to obtain a resin composition powder; adding at least one of a pre-prepared powder containing a low-melting-point resin and a powder containing a non-low-melting-point resin to the resin composition powder and mixing them to obtain a resin composition powder mixture in which the ratio of the content of the low-melting-point resin to the content of the non-low-melting-point resin is adjusted to a predetermined range; and molding the resin composition powder mixture to obtain a resin composition molded article. Attached Figure Description

[0012] Figure 1 This is a block diagram of a resin composition molding system that can be used in a method for manufacturing a resin composition molded article according to one embodiment of the present disclosure.

[0013] Figure 2This is a flowchart of a method for manufacturing a molded resin composition according to one embodiment of the present disclosure.

[0014] Figure 3 It is a model of a fountain flow within a mold that can be used in a method for manufacturing a resin composition molded body according to one embodiment of this disclosure. Detailed Implementation

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0016] It should be noted that in the following embodiment, a wood-based resin composition forming body containing wood flour is used as an example of a resin composition molding body to describe the manufacturing method.

[0017] Figure 1 This is a block diagram of a resin composition molding system that can be used in a method for manufacturing a resin composition molded article according to one embodiment of the present disclosure.

[0018] like Figure 1 As shown, the resin composition molding body manufacturing system 100 includes: a resin composition powder supply unit 10, a wood powder supply unit 20, a low melting point resin powder supply unit 30, a non-low melting point resin powder supply unit 40, an additive supply unit 50, and a molding body manufacturing unit 60.

[0019] The resin composition powder supply unit 10 manufactures and stores resin composition powder for manufacturing resin composition molded articles from plastic waste. The resin composition powder supply unit 10 includes: a plastic waste crusher 11, a magnetic separator 12, a non-magnetic metal separator 13, a washing machine 14, a compression and volume reduction machine 15, a pulverizer 16, a storage tank 17, and a metering tank 18.

[0020] Plastic waste includes low-melting-point resins with a melting point between 80°C and 190°C, as well as non-low-melting-point resins, namely high-melting-point resins with a melting point above 190°C and thermosetting resins, or a mixture of one or both. Plastic waste may also include substances other than synthetic resins. Substances other than synthetic resins can be inorganic or organic. Inorganic substances include magnetic materials, non-magnetic metals, glass, pebbles, metals, shells, sand, desiccants such as silica gel, and iron-based deoxidizers. Examples of magnetic materials include iron, cobalt, and nickel. Examples of non-magnetic metals include aluminum. Organic substances include oils, food scraps, and surfactants.

[0021] Examples of low-melting-point resins include polystyrene (PS), acrylonitrile-butadiene-styrene (ABS), polyethylene (PE), polymethyl methacrylate (PMMA), polycarbonate (PC), polypropylene (PP), polyamide 12 (PA12), and polyoxymethylene (POM). High-melting-point resins can have melting points below 340°C. Examples of high-melting-point resins include polyethylene terephthalate (PET), polyamide 6 (PA6), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and polyetheretherketone (PEEK). Thermosetting resins are resins that have been cured. Examples of thermosetting resins include polyimide (PI), polyurethane (PU), and phenolic resin (PF). Plastic waste may contain one or more low-melting-point and non-low-melting-point resins.

[0022] Plastic waste is, for example, waste containing any one or more of the following: waste plastics from general waste, waste plastics from industrial waste, and waste plastics from marine waste. Plastic refers to molded articles made of synthetic resins. For example, plastic waste is waste containing 50% by mass or more of waste plastics. The waste plastic content of plastic waste can, for example, range from 50% by mass to 100% by mass, from 50% by mass to 99.5% by mass, or from 50% by mass to 70% by mass.

[0023] The ignition residue of plastic waste can range from 0.5% to 10% by mass. The ignition residue is a value determined, for example, by the following methods.

[0024] (Method for determining the residue upon ignition)

[0025] The weight of the sample before heating was measured while it was placed in a crucible. The sample was then held at 600°C for 2 hours in a high-temperature electric furnace to ensure complete combustion of the organic components containing the synthetic resin. After cooling, the percentage of ignition residue was determined by dividing the weight of the remaining sample by its weight before heating.

[0026] General waste refers to waste other than industrial waste and marine plastic waste, including household waste from ordinary households. Examples of waste plastics from general waste include plastics used as containers and packaging materials for goods. Waste plastics from general waste can also be waste plastic residue. Waste plastic residue is the remaining portion after a portion of the resin contained in waste plastics from general waste has been separated and recycled, for example, the remaining portion after a portion of low-melting-point resin has been separated and recycled. The separated and recycled low-melting-point resin may, for example, contain at least one of PP, PE, and PS, or may contain both PP and PE. Waste plastic residue can also be the remaining portion after separating and recycling at least 5% by mass, or 5% to 95% by mass, or 5% to 50% by mass, or 5% to 15% by mass of low-melting-point resin contained in waste plastics. It should be noted that the combined percentage of PP and PE in the separated and recycled low-melting-point resin may be 20% by mass or more, or in the range of 50% to 100% by mass, or in the range of 70% to 100% by mass.

[0027] Waste plastics from industrial waste are plastics generated during business activities. Examples of waste plastics from industrial waste include defective products and surplus manufactured goods. Waste plastics from marine plastic waste are plastics accumulated in the ocean due to the direct dumping of plastic products into the sea, or plastic products discarded on land flowing into the sea via rivers or lakes. Examples of plastic products include plastic scraps, plastic bottles, fishing gear, etc. Waste plastics from marine plastic waste include, for example, microplastics (smaller than 5 mm) that have deteriorated due to waves and ultraviolet radiation.

[0028] There are no particular restrictions on the content of low-melting-point and non-low-melting-point synthetic resins in plastic waste. The content of low-melting-point resin can, for example, range from 3% to 95% by mass. The content of non-low-melting-point resin can, for example, range from 5% to 97% by mass. The ratio of low-melting-point resin to non-low-melting-point resin (low-melting-point resin / non-low-melting-point resin content ratio) can, for example, range from 1 / 3 to 5.00 by mass. The content of low-melting-point resin can be less than 80% by mass or less than 70% by mass. The content of low-melting-point resin can be in any range from 5% to 80% by mass, 25% to 80% by mass, 25% to 75% by mass, or 30% to 70% by mass. The content of non-low-melting-point resin can be more than 20% by mass or more than 30% by mass. The content of low-melting-point resin can be in any range of 20% to 95% by mass, 20% to 75% by mass, 25% to 75% by mass, or 30% to 70% by mass. The ratio of low-melting-point resin to non-low-melting-point resin can be less than 4.00 by mass, or it can be in the range of 1 / 3 to 3.00.

[0029] When plastic waste is waste plastic residue, the content of low-melting-point resin in the synthetic resin contained in the waste plastic residue can be, for example, less than 95% by mass, in the range of 25% to 95% by mass, or in the range of 35% to 90% by mass. The total content of PE, PP, and PS in the synthetic resin contained in the waste plastic residue can be less than 80% by mass, or less than 70% by mass. The total content of PE, PP, and PS can be in any range of 5% to 80% by mass, 25% to 80% by mass, 25% to 75% by mass, or 30% to 70% by mass. The total content of PE and PP relative to the total amount of low-melting-point resin can be less than 90% by mass, or in the range of 20% to 80% by mass. The content of non-low-melting-point resin in the above-mentioned synthetic resin can be, for example, more than 5% by mass, in the range of 5% to 75% by mass, or in the range of 10% to 65% by mass. The ratio of low-melting-point resin to non-low-melting-point resin in the aforementioned synthetic resin (low-melting-point resin / non-low-melting-point resin content ratio) can, for example, be in the range of 1 / 3 to 5.00 by mass, or in the range of 0.71 to 3.00. The low-melting-point resin / non-low-melting-point resin content ratio can be less than 4.00 by mass, or in the range of 1 / 3 to 3.00. The ratio of thermosetting resin to high-melting-point resin in the non-low-melting-point resin of the aforementioned synthetic resin (thermosetting resin / high-melting-point resin) can, for example, be in the range of 0.01 to 100 by mass, or in the range of 0.05 to 50. The content of thermosetting resin in the aforementioned synthetic resin can, for example, be 0% by mass or more, or in the range of 1% by mass to 10% by mass. The content of high-melting-point resin in the aforementioned synthetic resin can, for example, be 5% by mass or more, or in the range of 10% by mass to 90% by mass.

[0030] The form of plastic waste is not particularly limited; for example, it can be in bundles or blocks. When manufacturing units (batches) of resin compositions are divided according to the type of plastic waste, the location and timing of plastic waste generation in each manufacturing unit can differ. The standard deviation of the content of, for example, low-melting-point resin in the plastic waste used in each manufacturing unit can be greater than 1% by mass, or within the range of 1% to 23% by mass, or within the range of 2% to 12% by mass.

[0031] The crusher 11 is an apparatus for crushing plastic waste to obtain plastic flakes. For example, a single-shaft crusher can be used as the crusher 11. The size of the plastic flakes obtained by the crusher 11 is not particularly limited; for example, it can be the size of a sieve with a mesh size of 20 to 50 mm. The mesh size of the sieve can be 50 mm, 40 mm, or 30 mm.

[0032] The magnetic separator 12 is a device for removing and recycling magnetic materials contained in plastic sheets. Examples of magnetic separators 12 include suspended magnetic separators, wheeled magnetic separators, drum magnetic separators, and roller magnetic separators. Examples of magnetic materials include iron, stainless steel, and ferrite. The magnetic separator 12 can be used alone or in combination with two or more types.

[0033] The non-magnetic metal sorting machine 13 is a device for removing and recycling non-magnetic metals contained in plastic sheets. Examples of non-magnetic metals include aluminum, copper, zinc, and brass. A vortex separator can be used as the non-magnetic metal sorting machine 13.

[0034] The washing machine 14 is a device for cleaning and removing detergent, food stains, oil, and other contaminants adhering to plastic sheets. The washing machine 14 can be a wet shredder washing machine with a shredding function. The wet shredder washing machine is a device that shreds plastic sheets in water. For the shredding function, a shredder with fixed blades and rotating blades can be used, clamping the plastic sheet between the fixed and rotating blades for shredding. By using a wet shredder washing machine to shred the plastic sheet into coarse plastic particles while washing, the contaminants adhering to the coarse plastic particles can be removed more effectively.

[0035] The compression reduction machine 15 is an apparatus that compresses coarse plastic particles to remove moisture adhering to them and reduces their volume to obtain coarse plastic powder. The compression reduction machine 15 can be a screw-type compression reduction machine with a screw inside a cylinder having drainage holes. By using the screw-type compression reduction machine, moisture is removed by utilizing the frictional heat between the screw, cylinder, and coarse plastic particles. Simultaneously, a portion of the low-melting-point resin in the coarse plastic particles melts, causing the coarse plastic particles to fuse together, thereby reducing the volume of the coarse plastic particles.

[0036] The pulverizer 16 is an apparatus for pulverizing coarse plastic powder into fine resin composition powder. A micro-pulverizer (cutter), hammer mill, or pin mill can be used as the pulverizer 16. A micro-pulverizer (cutter) is an apparatus that has fixed blades and rotating blades, and clamps a plastic sheet between the fixed and rotating blades for pulverization. The pulverizer 16 can be used alone or in combination with two or more other types.

[0037] The outlet of the resin composition powder in the pulverizer 16 can also be equipped with a sieve. The pulverizer 16 can be designed, for example, to retain coarse plastic powder inside the pulverizer 16, and only remove the fine resin composition powder that passes through its sieve to the outside. As the sieve, for example, a sieve with a mesh size in the range of 1 to 3 mm can be used. The mesh size of the sieve can be 3 mm, 2 mm, or 1 mm. If the mesh size of the sieve is, for example, less than 500 μm, the heat generated by pulverizing the coarse plastic powder will melt the pulverized low-melting-point resin, and the molten resin may solidify on the surface of the sieve, causing sieve blockage.

[0038] Storage tank 17 is a tank for temporarily storing the resin composition powder generated in pulverizer 16. Additionally, metering tank 18 is a tank for metering and temporarily storing a predetermined amount of the resin composition powder delivered from storage tank 17.

[0039] In the resin composition powder supply unit 10, resin composition powder can be manufactured from plastic waste by, for example, a crushing process, a magnetic material removal process, a non-magnetic metal removal process, a water washing process, a volume reduction process, and a pulverizing process.

[0040] The crushing process is the process of breaking down plastic waste into plastic sheets. The crushing process is carried out using crusher 11.

[0041] The magnetic material removal process is a step to remove and recycle the magnetic materials contained in the plastic sheets. This process is performed using a magnetic separator 12. By performing this process, magnetic materials mixed into the plastic sheets can be reliably removed. Removing magnetic materials prevents the wear and damage to the internal blades of the crusher caused by magnetic materials remaining inside during the crushing process, thus preventing a gradual decrease in the crushing efficiency. Especially after the plastic waste is processed into plastic sheets through the crushing process, this magnetic material removal process further removes metallic magnetic materials such as spring materials and screw materials used in the containers of hand sanitizers and shampoos, as the molded components are crushed.

[0042] The non-magnetic metal removal process is a process of removing and recycling non-magnetic metals contained in the plastic sheet. This process is carried out using a non-magnetic metal sorting machine 13.

[0043] The washing process removes adhering substances (especially organic matter) from the plastic sheets by washing them with water. In the washing process S14, the adhering substances are removed while the plastic sheets are being crushed into coarse plastic particles. The washing process is performed using a washing machine 14. By performing the washing process, it is possible to prevent the organic matter such as detergent, food residue, and oil from melting and adhering to the blades inside the crusher during the crushing process, which would otherwise reduce crushing efficiency, or to prevent the organic matter from melting and adhering to the screen of the crusher, causing screen blockage. In addition, the amount of organic matter mixed in the resulting resin composition powder is reduced, making it difficult for microorganisms to grow.

[0044] The volume reduction process is a process of removing moisture adhering to the coarse plastic particles and reducing their volume to obtain coarse plastic powder. The volume reduction process is carried out using a compression volume reduction machine 15.

[0045] The pulverization process is the process of pulverizing coarse plastic powder to obtain resin composition powder. In the method for manufacturing resin composition powder of this embodiment, the pulverization process is performed simultaneously without separating the low-melting-point resin and non-low-melting-point resin contained in the plastic waste. The pulverization process is performed using a pulverizer 16. The resin composition powder obtained by pulverization is sent to a storage tank 17.

[0046] When plastic waste is in bundles or lumps, a shredder can be used to break it down before the crushing process. Additionally, plastic waste may contain various large magnetic materials such as batteries, lighters, aerosol cans, razors, and syringes. Therefore, a magnetic separator can be used before the crushing process to remove and recycle these large magnetic materials.

[0047] The wood flour supply unit 20 produces and stores wood flour from waste wood as raw material for molding resin compositions. The wood flour supply unit 20 includes a crusher 21, a magnetic separator 22, a pulverizer 23, a storage tank 24, and a metering tank 25.

[0048] As waste timber, for example, construction waste wood, thinning timber, and sawdust can be used.

[0049] The crusher 21 is a device for crushing waste wood to obtain wood chips. For example, a single-shaft crusher can be used as the crusher 21. The size of the wood chips obtained by the crusher 21 is not particularly limited; for example, they can be the size of those that pass through a sieve with a mesh size of 20 to 50 mm. The mesh size of the sieve can be 50 mm, 40 mm, or 30 mm.

[0050] The magnetic separator 22 is a device for removing and recovering magnetic materials contained in wood chips. Examples of magnetic separators 22 include suspended magnetic separators, wheeled magnetic separators, drum magnetic separators, and roller magnetic separators. Examples of magnetic materials include nails and bolts. The magnetic separator 12 can be used alone or in combination with two or more types.

[0051] The pulverizer 23 is a device for pulverizing wood chips to produce fine wood powder. A micro-pulverizer (cutter), hammer mill, or pin mill can be used as the pulverizer 23. The pulverizer 23 can be used alone or in combination with two or more other types.

[0052] The wood flour outlet of the pulverizer 23 can also be equipped with a sieve. The pulverizer 16 can be designed, for example, to retain coarse plastic powder inside the pulverizer 16, and only remove the fine resin composition powder that passes through its sieve to the outside. As a sieve, for example, a sieve with a mesh size in the range of 300 μm to 3 mm can be used. The mesh size of the sieve can be 2 mm, 1 mm, or 500 μm.

[0053] There is no particular limitation on the particle size of the wood flour. Among particles with a major diameter of 1.0 mm or more, the content of particles with a major diameter of 3.0 mm or more can be less than 35% or less, or less than 20%. Furthermore, the content of particles with a major diameter less than 2.0 mm can be more than 30% or less, or less than 50%. The content of these particles can be determined by observing the cross-section of the resin composition molded body 10 using an optical microscope and measuring the particle size of the wood flour.

[0054] Storage tank 24 is a tank for temporarily storing wood flour generated in pulverizer 23. In addition, metering tank 25 is a tank for metering and temporarily storing a specified amount of wood flour delivered from storage tank 24.

[0055] The low-melting-point resin powder supply unit 30 stores low-melting-point resin powder, which is used as a raw material for molding resin compositions, as needed. The low-melting-point resin powder supply unit 30 includes a storage tank 31 and a metering tank 32.

[0056] Low-melting-point resin powder is a powder composed of resins having a melting point higher than that of low-melting-point resins contained in plastic waste. Low-melting-point resin powder contains low-melting-point resins. Examples of low-melting-point resins include PS, ABS, PE, PMMA, PC, PP, PA12, and POM. A single low-melting-point resin can be used alone, or two or more can be used in combination. When multiple low-melting-point resins are included, the melting point of the low-melting-point resin refers to the lowest temperature among the melting points of the various low-melting-point resins. Low-melting-point resin powder may also contain non-low-melting-point resins. The content of low-melting-point resin in the low-melting-point resin powder can be, for example, 60% by mass or more, or 80% by mass or more. Low-melting-point resin powder can also be obtained by pulverizing plastic waste containing 60% by mass or more of low-melting-point resin. Low-melting-point resin powder can also be powder that passes through a sieve with a mesh size of 3 mm. As a low-melting-point resin powder, for example, powder obtained by crushing waste materials such as shrink film (PE), strapping tape (PP), and expanded polystyrene (PS) used for packaging, bundling, and curing of products to a thickness of 3 mm or less can be used. Alternatively, powder obtained by crushing recycled plastics (PP, PE, PS) recycled and manufactured based on container packaging recycling methods to a thickness of 3 mm or less can also be used.

[0057] Storage tank 31 is a tank for temporarily storing low-melting-point resin powder. In addition, metering tank 32 is a tank for metering and temporarily storing a specified amount of low-melting-point resin powder delivered from storage tank 31.

[0058] The non-low melting point resin powder supply unit 40 stores non-low melting point resin powder, which is used as a raw material for molding resin compositions, as needed. The non-low melting point resin powder supply unit 40 includes a storage tank 41 and a metering tank 42.

[0059] Non-low-melting-point resin powder is a powder composed of resins having a melting point higher than that of low-melting-point resins contained in plastic waste. Non-low-melting-point resin powder contains non-low-melting-point resins. Examples of non-low-melting-point resins include PET, PA6, PBT, PPS, PEEK, PI, PU, ​​and PF. A single non-low-melting-point resin can be used alone, or two or more can be used in combination. When multiple non-low-melting-point resins are included, the melting point of the non-low-melting-point resin refers to the lowest temperature among the melting points of the various non-low-melting-point resins. Non-low-melting-point resin powder may also contain non-low-melting-point resins. The content of non-low-melting-point resins in non-low-melting-point resin powder may, for example, be 60% by mass or more, or 80% by mass or more. Non-low-melting-point resin powder may also be obtained by pulverizing plastic waste containing 60% by mass or more of non-low-melting-point resins. Non-low-melting-point resin powder may also be powder that passes through a sieve with a mesh size of 3 mm. As a non-low melting point resin powder, recycled raw materials such as powder obtained by crushing waste materials such as PET used for egg sales containers and food packaging materials to less than 3mm can be used.

[0060] Storage tank 41 is a tank for temporarily storing non-low melting point resin powder. In addition, metering tank 42 is a tank for metering and temporarily storing a specified amount of non-low melting point resin powder delivered from storage tank 41.

[0061] The additive supply unit 50 stores any additives that can be added to the molded resin composition. The additive supply unit 50 includes a storage tank 51 and a metering tank 52.

[0062] As additives, various additives previously used in resin composition moldings can be used, such as pigments, compatibilizers to improve the affinity between resin and wood flour, fillers, lubricants, weathering agents, heat stabilizers, foaming agents, and antistatic agents. Pigments are used to color the resin composition moldings. Inorganic pigments, organic pigments, and mixtures thereof can be used as pigments. Compatibilizers can be used to improve the adhesion between wood flour and resin components, and to improve the strength, physical properties, and water resistance of the resin composition moldings. Maleic anhydride-modified polypropylene compatibilizers can be used as compatibilizers. Lubricants are added to improve sliding properties with the mold. Oxidized polyolefin waxes, acid-modified polyolefin waxes, calcium stearate, and zinc stearate can be used as lubricants. As weather-resistant materials, ultraviolet A (UVA) absorbers, light absorbers (HALS), and antioxidants can be used.

[0063] Storage tank 51 is a tank for temporarily storing additives. Metering tank 52 is a tank for metering and temporarily storing a predetermined amount of additives delivered from storage tank 51. Storage tank 51 and metering tank 52 can be provided separately for each type of additive, or one can be provided for a mixture of two or more additives.

[0064] The molding body manufacturing unit 60 manufactures molded bodies of resin compositions. The molding body manufacturing unit 60 includes a mixer 61, a storage tank 62, and an extruder 63.

[0065] Mixer 61 is an apparatus for mixing at least one of the following: resin composition powder, powder containing a low-melting-point resin, and powder containing a non-low-melting-point resin, wood flour, and additives, which will become raw materials for the molding of the resin composition, to obtain a raw material mixture. For example, a heated mixer can be used as mixer 61. By mixing the above raw materials while heating them using a heated mixer, a mixture in which each raw material is uniformly dispersed can be obtained. The heating temperature of the heated mixer varies depending on the resin contained in the raw material mixture; for example, when the resin with the lowest melting point is PE, it can be in the range of 100 to 150°C.

[0066] Storage tank 62 is a tank for temporarily storing the raw material mixture. Storage tank 62 supplies a specified amount of the raw material mixture to extruder 63.

[0067] The extruder 63 is an apparatus for molding a raw material mixture into a predetermined shape. For example, a single-spindle extruder or a twin-spindle extruder can be used as the extruder 63. The molding temperature of the extruder 63 varies depending on important factors such as the type and content of low-melting-point resins contained in the raw material mixture; for example, it is 150°C or higher when PE is included. On the other hand, wood flour decomposes and vaporizes at temperatures above 190°C, which may generate bubbles in the molded resin composition; therefore, the molding temperature is preferably less than 190°C.

[0068] Next, a method for manufacturing a resin composition molded article using the resin composition molding article manufacturing system 100 will be described. Figure 2 This is a flowchart of a method for manufacturing a molded resin composition according to one embodiment of the present disclosure.

[0069] The method for manufacturing a resin composition molded article according to this embodiment includes an analysis step S1, a mixing step S2, and a molding step S3.

[0070] Analysis step S1 is a step of analyzing the composition of the resin composition powder. The composition of the resin composition powder can be determined by the ratio of the content of low-melting-point resin to the content of non-low-melting-point resin. The resin composition powder (sample powder) to be analyzed can be, for example, the resin composition powder stored in the storage tank 17 of the resin composition powder supply unit 10.

[0071] The analysis of the content of low-melting-point resin and non-low-melting-point resin in the resin composition powder can be performed, for example, by separating the low-melting-point resin and non-low-melting-point resin based on their specific gravity difference, and then determining the content of each separated resin. In this embodiment, the analysis is performed as follows.

[0072] The resin composition powder is immersed in a heavy liquid as the sample powder. Then, the amount of floating matter on the surface of the heavy liquid and the amount of precipitated matter are measured. The floating matter is removed from the heavy liquid. The precipitate is recovered by filtering the heavy liquid after all the floating matter has been removed. The recovered floating matter and precipitate are washed with water, dried, and their amounts are measured. Then, the amount of floating matter is taken as the content of low-melting-point resin, and the amount of precipitate is taken as the content of non-low-melting-point resin. The specific gravity of the heavy liquid can be set, for example, from 1.08 to 1.13. The heavy liquid can be, for example, an organic solvent such as ethylene glycol, or an aqueous solution of inorganic salts such as sodium chloride. To prevent the sample powder from floating due to buoyancy, the particle size of the sample powder can be set to 3 mm or less. Furthermore, if air bubbles adhere to the sample powder, the resin powder that should have precipitated in the heavy liquid may float. By stirring under appropriate conditions and adding surfactants to the heavy liquid, the adhesion of air bubbles can be suppressed, improving analytical accuracy.

[0073] Mixing step S2 is a process of mixing resin composition powder, powder containing low-melting-point resin and powder containing non-low-melting-point resin, wood flour, and additives to obtain a raw material mixture. Mixing step S2 is performed by mixing the raw materials delivered from metering tanks 18, 25, 32, 42, and 52 using a mixer 61. The resulting raw material mixture is then sent to storage tank 62.

[0074] In the mixing step S2, the mixing ratio of the resin composition powder, the powder containing the resin with a melting point, and / or the powder containing the non-low melting point resin is adjusted based on the ratio of the content of low-melting-point resin to the content of non-low-melting-point resin in the resin composition powder obtained in the analysis step S1. The total content of low-melting-point resin and non-low-melting-point resin in the raw material mixture obtained in the mixing step S2 can, for example, be in the range of 50 to 90% by mass. The content of wood flour can, for example, be in the range of 5 to 40% by mass. The content of additives can, for example, be in the range of 5 to 40% by mass. The ratio of wood flour content to low-melting-point resin content (wood flour / low-melting-point resin content ratio) can be 5.0 or less. Furthermore, the ratio of the content of low-melting-point resin to non-low-melting-point resin in the resin composition powder mixture, by mass ratio, can be in the range of 1 / 3 to 5, or in the range of 1 / 3 to 1.40.

[0075] Molding step S3 is a process of molding the raw material mixture obtained in mixing step S2 to obtain a wood resin composition molded body. Molding step S3 is performed by extruding the raw material mixture fed from storage tank 62 using extruder 63. By performing extrusion molding, the low-melting-point resin in the resin composition powder melts, and a wood resin composition molded body in which non-low-melting-point resin and wood powder are dispersed in the low-melting-point resin can be obtained. The shape of the wood resin composition molded body is not particularly limited, for example, it can be plate-shaped.

[0076] Figure 3 It is a model of a fountain flow within a mold that can be used in a method for manufacturing a molded resin composition according to one embodiment of this disclosure. For example... Figure 3 As shown, the molten material 300 of the raw material powder mixture flowing within the mold 200 forms a fountain flow 301, flowing from the flow front 302 towards the inner surface of the mold 200 and solidifying to form a surface layer 310. The flow velocity of the molten material 300 within the mold 200 differs between the central part of the mold 200 and near the inner surface. This velocity difference varies depending on factors such as the viscosity of the molten material 300 and the slippage between the mold 200 and the molten material 300. If the velocity difference of the molten material 300 increases, it becomes difficult to uniformly discharge the molten material 300 from the mold 200, resulting in defects in the shape of the molded body. This is particularly problematic in the case of irregularly shaped extrusions such as window frames (with complex cross-sectional shapes and varying wall thicknesses), which can lead to warping and decreased dimensional accuracy.

[0077] The viscosity of the melt 300 varies significantly depending on the ratio of low-melting-point resin to non-low-melting-point resin. In this embodiment, the ratio of low-melting-point resin to non-low-melting-point resin in the resin composition powder is determined by the analysis step S1, and the content of low-melting-point resin to non-low-melting-point resin is adjusted to an appropriate ratio by the mixing step S2, thus stably maintaining the viscosity of the melt 300. Therefore, the moldability during extrusion can be improved. As a result, plastic waste can be applied to shapes that are difficult to mold, such as window frames, thereby broadening the development goals for the effective utilization of plastic waste.

[0078] In molding step S3, the molding temperature of the raw material mixture is preferably less than 10°C below the melting point of the non-low-melting-point resin contained in the raw material mixture. For example, if the melting point of the non-low-melting-point resin is 250°C, the molding temperature is preferably less than 240°C. In the wood resin composition, by leaving the non-low-melting-point resin in an unmelted state without melting, the non-low-melting-point resin is dispersed in an island-like manner in the molded body, acting as a filler. Since the non-low-melting-point resin has a higher elastic modulus than the low-melting-point resin, the island-like dispersion of the non-low-melting-point resin can reinforce the low-melting-point resin, which is sea-like and has a low elastic modulus. Therefore, the overall molded body of the resin composition has high elasticity and high strength. In addition, in the compounding system containing wood flour, if the molding temperature reaches 200°C or higher, the wood flour may carbonize, so molding is preferably performed at 190°C or lower. The molding temperature of the raw material mixture is preferably 5 to 10°C or higher above the melting point of the low-melting-point resin. The molding temperature of the raw material mixture can also be in the range of 160°C to 190°C, for example. It should be noted that the melting point of a non-low-melting-point resin refers to the lowest temperature among the melting points of the various non-low-melting-point resins contained in the raw material mixture. The melting point of a low-melting-point resin indicates the highest temperature among the melting points of the various low-melting-point resins contained in the raw material mixture.

[0079] From the viewpoint of improving the elasticity and strength of the molded resin composition, the resin composition powder is preferably fine, and more preferably a powder that has passed through a sieve with a mesh size of 1 mm.

[0080] The resin composition formed above contains wood flour and has a texture similar to wood, thus it can be used as a wood substitute. The resin composition formed can be used, for example, as a civil material, building material, and gardening material. Examples of civil materials include paving materials. Examples of building materials include flooring materials, especially bathroom flooring, roofing materials, wall materials, handrails, window frames, wooden decks, fences, etc. Examples of gardening materials include flower beds.

[0081] In the method for manufacturing a resin composition molded body according to the above embodiment, at least one of a pre-prepared powder containing a low-melting-point resin and a powder containing a non-low-melting-point resin is added to a resin composition powder derived from plastic waste and mixed. The ratio of the content of the low-melting-point resin to the content of the non-low-melting-point resin is adjusted to a predetermined range, and the resulting resin composition powder mixture is then molded to obtain a resin composition molded body. Therefore, even when the proportions of the low-melting-point resin and the non-low-melting-point resin contained in the plastic waste are different, a resin composition molded body can be stably manufactured as a molding raw material without separating the low-melting-point resin and the non-low-melting-point resin. Therefore, according to this embodiment, a method for manufacturing a resin composition molded body can be provided that can effectively utilize plastic waste with unknown resin (low-melting-point resin and non-low-melting-point resin) proportions.

[0082] In the method for manufacturing a resin composition molded body according to this embodiment, the content of low-melting-point resin and non-low-melting-point resin in the resin composition powder is determined by the analysis step S1. Based on the obtained content measurement value, the amount of powder containing low-melting-point resin and powder containing non-low-melting-point resin added to the resin composition powder is adjusted, thereby enabling the resin composition molded body to be manufactured more stably.

[0083] In the method for manufacturing the molded resin composition of this embodiment, the method for determining the content of low-melting-point resin and non-low-melting-point resin in the resin composition powder during the analysis step S1 involves immersing the sample powder (resin composition powder) in a heavy liquid, measuring the amount of floating matter on the surface of the heavy liquid and the amount of precipitated matter, using the amount of floating matter as the content of low-melting-point resin and the amount of precipitated matter as the content of non-low-melting-point resin. This method allows for rapid and highly accurate determination of the content of both low-melting-point and non-low-melting-point resin. Furthermore, by setting the specific gravity of the heavy liquid to 1.08 to 1.13, the content of both low-melting-point and non-low-melting-point resin can be determined with even greater accuracy.

[0084] In the method for manufacturing a resin composition molded body according to this embodiment, by means of the mixing step S2, the amount of powder containing low-melting-point resin and powder containing non-low-melting-point resin added to the resin composition powder from plastic waste is adjusted so that the ratio of the content of low-melting-point resin to the content of non-low-melting-point resin in the resin composition powder mixture is in the range of 1 / 3 to 5 by mass, thereby obtaining a resin composition molded body that is not easily damaged during molding and has excellent water resistance.

[0085] In the method for manufacturing a resin composition molded article according to this embodiment, when resin composition powder from plastic waste passes through a sieve with a mesh size of 3 mm, the non-low melting point resin is finely ground, allowing the non-low melting point resin to be coated with a melt of low melting point resin during the manufacturing of the resin composition molded article. Therefore, the water resistance of the resulting resin composition molded article is further improved.

[0086] In the method for manufacturing a molded resin composition according to this embodiment, when the powder containing low-melting-point resin added to the resin composition powder from plastic waste contains 60% or more of low-melting-point resin, the amount of low-melting-point resin added is easily adjusted when the amount of low-melting-point resin in the resin composition powder is low, since the content of low-melting-point resin in the powder is high. Furthermore, in the method for manufacturing a molded resin composition according to this embodiment, when the powder containing non-low-melting-point resin added to the resin composition powder from plastic waste contains 60% or more of non-low-melting-point resin, the amount of non-low-melting-point resin added is easily adjusted when the amount of non-low-melting-point resin in the resin composition powder is low, since the content of non-low-melting-point resin in the powder is high.

[0087] In the method for manufacturing a resin composition molded article according to this embodiment, wood flour is added to a resin composition powder derived from plastic waste and mixed to obtain a resin composition powder mixture containing wood flour. This wood flour-containing resin composition powder mixture is then molded to obtain a resin composition molded article with a texture similar to wood. Cellulose-based material powders such as pulp powder can be used instead of wood flour.

[0088] The embodiments of this disclosure have been described above, but this disclosure is not limited thereto. In this embodiment, the content of low-melting-point resin and non-low-melting-point resin in the resin composition powder from plastic waste is determined by the analysis step S1, but the analysis step S1 is not a necessary component. For example, if the content of low-melting-point resin and non-low-melting-point resin in the plastic waste is known, the analysis step S1 can be omitted. Furthermore, if the analysis result in the analysis step S1 determines that it is not necessary to add low-melting-point resin powder and non-low-melting-point resin powder to the resin composition powder, the mixing step can also be omitted. In addition, in this embodiment, the content of low-melting-point resin and non-low-melting-point resin in the resin composition powder is determined in the analysis step S1, but it is also possible to only determine the low-melting-point resin and use the amount obtained by subtracting the content of low-melting-point resin from the resin composition powder as the content of non-low-melting-point resin, or to only determine the non-low-melting-point resin and use the amount obtained by subtracting the content of non-low-melting-point resin from the resin composition powder as the content of low-melting-point resin. Furthermore, in this embodiment, the content of low-melting-point resin and non-low-melting-point resin in the resin composition powder is determined by gravity difference in analysis step S1, but the determination method is not limited to this. For example, DSC (differential scanning calorimetry), GC-MS (gas chromatography-mass spectrometry), infrared absorption spectroscopy, and elemental analysis (CHN coding) can also be used. When using DSC, the content of non-low-melting-point resin can be determined, and the amount obtained by subtracting the content of non-low-melting-point resin from the resin composition powder is taken as the content of low-melting-point resin.

[0089] In this embodiment, the resin composition powder stored in the storage tank 17 of the resin composition powder supply unit 10 is used as the sample powder for analysis step S1, but the sample powder is not limited to this. For example, coarse plastic powder pulverized by the washing machine 14 can also be used as the sample powder, or plastic flakes before coarse pulverization can also be used. In addition, when using coarse plastic powder or plastic flakes as the sample powder, the coarse plastic powder or plastic flakes can be mixed with wood flour and then finely pulverized.

[0090] In this embodiment, molding step S3 is performed by extrusion molding, but the molding method of the resin composition molded body is not limited to this. The molding method of the resin composition molded body can be any method that melts the low-melting-point resin of the resin composition powder to form a molten resin composition. For example, the molding method of the resin composition molded body can be injection molding, compression molding, casting molding, or lamination molding using a 3D printer.

[0091] Furthermore, in this embodiment, a wood-based resin composition forming body containing wood flour is used as an example of a resin composition molding body, but it may also be without wood flour, as long as it contains resin composition powder from plastic waste. Additionally, in this embodiment, waste wood is used as the raw material for wood flour, but the raw material for wood flour is not limited to waste wood.

[0092] Example

[0093] The present disclosure will now be described in further detail with reference to embodiments. The present disclosure is not limited to these embodiments. It should be noted that the following materials are used in this embodiment.

[0094] Resin composition powders A to D: Resin composition powders obtained using waste plastic residues from general waste. The composition of the resin composition powders is shown in Table 1 below. The manufacturing method and composition analysis method of the resin composition powders are as follows.

[0095] (Method for manufacturing resin composition powder)

[0096] As plastic waste, four types of bundled waste plastic residues from general waste were prepared. The content of non-low-melting-point resins in the four types of waste plastics was determined, and the standard deviation was calculated. The result was 22.2% by mass. The bundled waste plastic residues were obtained by separating and recovering low-melting-point resins (polyethylene, polypropylene, and polystyrene) from plastic waste recycled according to the container packaging recycling method, and then compressing the waste plastic residues after separating and recovering the low-melting-point resins into bundled waste plastic residues. The waste plastic residues contained PP, PE, PS, PA6, and PET.

[0097] First, bundled waste plastic residue is fed into a crusher for crushing. The resulting crushed material is then passed through a high-magnetic-force belt-driven magnetic separator with a magnetic force of 20,000 Gauss to remove iron-containing substances. Next, the iron-free crushed material is crushed into plastic flakes using a single-shaft coarse crusher until it passes through a 50mm mesh sieve. Magnetic materials contained in the obtained plastic flakes are removed and recycled using a suspended magnetic separator and a belt-driven magnetic separator. Then, non-magnetic metals contained in the plastic flakes are removed and recycled using a non-magnetic metal separator. Next, the adhering substances to the plastic flakes are crushed into plastic particles through a 12mm mesh sieve using a wet crushing and washing machine, resulting in coarse plastic particles. Next, the coarse plastic particles obtained from the wet crushing and washing machine are compressed and dehydrated using a volume-reducing compression dewatering machine to reduce their volume, resulting in coarse plastic powder with a moisture content of 0.5% by mass. Finally, the coarse plastic powder is crushed into plastic powder through a 1mm mesh sieve using a cutting-type crusher. This yields resin composition powders A to D.

[0098] (Analytical methods for the composition of resin composition powder)

[0099] 500 mL of water and 100 g of sodium chloride were stirred until the sodium chloride dissolved to obtain a sodium chloride aqueous solution. Separately, a commercially available liquid detergent (trade name: NANOX laundry detergent for deodorizing, manufactured by Lion Corporation) was diluted 100 times to obtain a surfactant aqueous solution. 4.4 mL of the surfactant aqueous solution was added to the sodium chloride aqueous solution and stirred to prepare a sodium chloride aqueous solution (heavy liquid) for compositional analysis.

[0100] The sodium chloride aqueous solution for composition analysis was stirred using a magnetic stirrer at an intensity sufficient to create a vortex, and 60 g of resin composition powder was added to the vortex. After stirring for 5 minutes, the magnetic stirrer was stopped, and the mixture was allowed to stand for 10 minutes. All floating matter that rose to the surface of the sodium chloride aqueous solution after standing was skimmed off. The sodium chloride aqueous solution after skimming off all floating matter was filtered through filter paper, and any precipitates or floating particles were recovered. The recovered floating matter and precipitates were thoroughly washed with clean water and then dried overnight at 40°C using a dryer. The weights of the dried floating matter and precipitates were measured. The content of the floating matter was taken as the content of low-melting-point resin (PP, PE, PS), and the content of the precipitates was taken as the content of non-low-melting-point resin (PA6, PET). The ratio of low-melting-point resin content to non-low-melting-point resin content was calculated using the following formula. The results are shown in Table 1 below.

[0101] Low-melting-point resin content / non-low-melting-point resin content ratio = weight of low-melting-point resin / weight of non-low-melting-point resin

[0102]

[0103] The low-melting-point resin powder is obtained by mixing three raw materials—low-density polyethylene (manufactured by Asahi Kasei Corporation, Suntec LD M1920), polypropylene (manufactured by Prime Polymer Corporation, J106G), and polystyrene (manufactured by PS Japan Corporation, GPPS HF77)—at a ratio of 33.3% by mass and then pulverizing them through a sieve with a mesh size of 3 mm.

[0104] Non-low melting point resin powder: PET powder obtained by crushing PET waste and passing it through a 3mm mesh sieve.

[0105] Wood flour: Wood flour obtained by crushing waste wood and passing it through a sieve with a mesh size of 300mm.

[0106] Additives: A mixture comprising 3 parts by weight of pigment, 3 parts by weight of compatibilizer (maleic anhydride modified polypropylene compatibilizer), 1 part by weight of lubricant, and 1 part by weight of weathering agent.

[0107] [Example 1]

[0108] Low-melting-point resin powder is added to resin composition powder A at a ratio of low-melting-point resin content to non-low-melting-point resin content of 1.40, and the mixture is mixed using a mixer to obtain a resin composition powder mixture.

[0109] The obtained resin composition powder mixture (60 parts by weight), wood flour (30 parts by weight), and additives (10 parts by weight) were mixed at 150°C using a heated mixer. The mixture was then shaped using an extruder with a die A having a rectangular cross-section of 30 mm thickness and 300 mm width to obtain a sheet-like resin composition molded body.

[0110] The molded articles of the obtained resin composition were evaluated for moldability and water resistance using the following method. The results, together with the composition of the molded articles of the resin composition calculated based on the composition of the resin composition powder and the proportions of each raw material, are shown in Table 3 below.

[0111] (Moldability)

[0112] The appearance of the molded resin composition is visually observed to determine its moldability. The case where the number of cracks with a length of 1 mm or more at the end of the molded resin composition in the width direction is 2 or less is designated as "A", the case where the number of cracks is 3 or more is designated as "B", and the case where there is a large defect at the end is designated as "C".

[0113] (Water resistance)

[0114] The resin composition molded body was immersed in warm water adjusted to 60°C. The resin composition molded body was removed from the warm water each day, and its thickness was measured. The rate of change of the thickness of the resin composition molded body relative to the thickness of the previous day was calculated using the following formula (1).

[0115] The rate of change in the thickness of the resin composition molded body (%) = (thickness of the resin composition molded body - thickness of the resin composition molded body on the previous day) / thickness of the resin composition molded body on the previous day × 100 (1)

[0116] When the rate of change of the thickness of the resin composition molded body is less than 0.5%, it is considered that the expansion rate of the thickness of the resin composition molded body due to water absorption has reached equilibrium, and the equilibrium expansion rate of the thickness of the resin composition molded body is calculated using the following formula (2). It should be noted that the thickness of the resin composition molded body is the average of the thicknesses at five points: the central part of the plane and the parts near each of the four corners.

[0117] Equilibrium expansion rate (%) = {(Tf - Ti) / Ti} × 100 (2)

[0118] In the above formula, Tf (unit: mm) is the thickness of the resin composition molded body when the thickness change rate is less than 0.5%, and Ti (unit: mm) is the thickness of the resin composition molded body before immersion in warm water.

[0119] Regarding water resistance, cases with an equilibrium expansion rate of less than 10% are designated as "A", cases with an expansion rate of more than 10% but less than 20% are designated as "B", and cases with an expansion rate of more than 20% are designated as "C".

[0120] [Examples 2-8]

[0121] The resin composition powder shown in Table 2 below was added to the resin composition powder in a ratio of low-melting-point resin content to non-low-melting-point resin content as shown in Table 2. Otherwise, the resin composition powder was prepared in the same manner as in Example 1. Plate-shaped resin composition molded articles were prepared using the resulting resin composition powder mixture in the same manner as in Example 1. It should be noted that in Examples 6-8, the extruder die used was die B with a rectangular cross-section of 30 mm thickness and 120 mm width. The moldability and water resistance of the resulting resin composition molded articles were evaluated in the same manner as in Example 1. The results are shown in Table 3 below.

[0122] [Refer to Examples 1-5]

[0123] Using the powders shown in Table 3 below as the resin composition powder, 60 parts by weight of the resin composition powder, 30 parts by weight of the wood flour, and 10 parts by weight of the additives were mixed at 150°C using a heated mixer. Otherwise, a sheet-like resin composition molded body was prepared in the same manner as in Example 1. It should be noted that in Reference Example 5, the extruder die used was die B with a rectangular cross-section of 30 mm thickness and 120 mm width. The moldability and water resistance of the resulting resin composition molded body were evaluated in the same manner as in Example 1. The results are shown in Table 3 below.

[0124]

[0125]

[0126] According to the results in Table 3, the moldability of the raw material powder mixture obtained by adding at least one of a pre-prepared powder containing a low-melting-point resin and a powder containing a non-low-melting-point resin to the resin composition powder from plastic waste is improved, and the resin composition molded body can be manufactured stably. The water resistance of the resin composition molded bodies obtained in Reference Examples 1 and 2 is reduced. This is because the content of low-melting-point resin is low, and the highly absorbent wood flour cannot be fully coated with low-melting-point resin, resulting in water absorption by the wood flour. In addition, although the resin composition molded body obtained in Reference Example 3 has the same composition as the resin composition molded body obtained in Example 7, the molded body size is reduced. This is because the width of mold B used in Example 7 is 120 mm, while the width of mold A used in Reference Example 3 is 300 mm, resulting in a larger difference in the flow rate of the melt of the raw material powder mixture in the mold. The moldability of the molded bodies obtained in Reference Examples 4 and 5 is reduced. This is because the high content of low-melting-point resin in the raw material powder mixture reduces the viscosity of the melt, resulting in excessively high fluidity of the melt within the mold. This leads to a greater difference in flow rate between the two ends in contact with the inner surface of the mold and the central portion not in contact with the inner surface. Compared to the resin composition molded body obtained in Reference Example 5, the moldability of the molded body obtained in Reference Example 4 is lower. This is because the width of mold A used in Reference Example 4 is 300 mm, increasing the flow rate difference of the melt within the mold.

[0127] The manner of this disclosure is shown in the following appendix.

[0128] (Note 1)

[0129] A method for manufacturing a molded resin composition.

[0130] Prepare plastic waste containing low-melting-point resin and non-low-melting-point resin with melting points above 80°C and below 190°C, wherein the non-low-melting-point resin is one or a mixture of high-melting-point resin and thermosetting resin with melting points above 190°C.

[0131] The above-mentioned plastic waste was crushed to obtain resin composition powder;

[0132] Add at least one of a pre-prepared powder containing a low-melting-point resin and a powder containing a non-low-melting-point resin to the above-mentioned resin composition powder and mix them to obtain a resin composition powder mixture in which the ratio of the content of the low-melting-point resin to the content of the non-low-melting-point resin is adjusted to a predetermined range.

[0133] The above-mentioned resin composition powder mixture is molded to obtain a resin composition molded body.

[0134] (Note 2)

[0135] According to the method for manufacturing a molded article of the resin composition described in Appendix 1, the content of at least one of the low-melting-point resin and the non-low-melting-point resin in the aforementioned plastic waste is determined.

[0136] Based on the measured values ​​of the above-mentioned content, the amounts of the powder containing the low-melting-point resin and the powder containing the non-low-melting-point resin added to the above-mentioned resin composition powder are adjusted.

[0137] (Note 3)

[0138] According to the method for manufacturing the molded resin composition described in Appendix 2, the method for determining the content of the low-melting-point resin and the non-low-melting-point resin in the aforementioned plastic waste is as follows:

[0139] The sample powder obtained by crushing the above-mentioned plastic waste was impregnated with a heavy liquid.

[0140] Measure the amount of floating matter that rises to the surface of the heavy liquid and the amount of precipitated matter.

[0141] The amount of the above-mentioned floating matter is taken as the content of the above-mentioned low-melting-point resin, and the amount of the above-mentioned precipitate is taken as the content of the above-mentioned non-low-melting-point resin.

[0142] (Note 4)

[0143] According to the method for manufacturing the resin composition molded article described in Appendix 3, the specific gravity of the above-mentioned heavy liquid is 1.08 to 1.13.

[0144] (Note 5)

[0145] According to the method for manufacturing the resin composition molded article as described in Appendix 3 or 4, the above-mentioned heavy liquid is an aqueous solution of sodium chloride.

[0146] (Note 6)

[0147] According to the method for manufacturing a molded resin composition according to any one of Appendices 1 to 5, the amounts of the powder containing the low-melting-point resin and the powder containing the non-low-melting-point resin added to the resin composition powder are adjusted such that the mass ratio of the content of the non-low-melting-point resin to the content of the low-melting-point resin in the resin composition powder mixture is in the range of 1 / 3 to 5.

[0148] (Note 7)

[0149] The method for manufacturing a molded resin composition according to any one of Appendices 1 to 6, wherein the resin composition powder is a powder that has passed through a sieve with a mesh size of 3 mm.

[0150] (Note 8)

[0151] The method for manufacturing a molded resin composition according to any one of Appendices 1 to 7, wherein the powder containing the low-melting-point resin contains 60% by mass or more of the low-melting-point resin.

[0152] (Note 9)

[0153] The method for manufacturing a molded resin composition according to any one of Appendices 1 to 8, wherein the powder containing the non-low melting point resin contains 60% by mass or more of the non-low melting point resin.

[0154] (Postscript 10)

[0155] The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 9, wherein a pre-prepared cellulose-based material powder is added to the resin composition powder and mixed to obtain a resin composition powder mixture containing cellulose-based material, and the resin composition powder mixture containing cellulose-based material is molded.

[0156] (Postscript 11)

[0157] According to the method for manufacturing a resin composition molded article according to any one of Appendices 1 to 10, the manufacturing units of the resin composition molded article are divided according to the type of plastic waste, and the standard deviation of the content of low melting point resin in the synthetic resin contained in the plastic waste used in each manufacturing unit is 1% by mass or more.

[0158] (Postscript 12)

[0159] According to the method for manufacturing the molded resin composition as described in Appendix 11, the standard deviation of the content of the aforementioned low-melting-point resin is 2% by mass or more.

[0160] (Postscript 13)

[0161] The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 12, wherein the resin composition molded body is formed by extruding the resin composition powder.

[0162] (Postscript 14)

[0163] According to the method for manufacturing the resin composition molded article described in Appendix 13, the molding temperature of the extrusion molding is less than -10°C of the melting point of the non-low melting point resin contained in the resin composition powder.

[0164] (Postscript 15)

[0165] A method for manufacturing a molded resin composition.

[0166] Prepare plastic waste containing low-melting-point resins and non-low-melting-point resins with melting points above 80°C and below 190°C, wherein the non-low-melting-point resins are high-melting-point resins or thermosetting resins with melting points above 190°C.

[0167] The above-mentioned plastic waste was crushed to obtain resin composition powder;

[0168] After determining the content of at least one of the low-melting-point resin and the non-low-melting-point resin in the above-mentioned plastic waste, the above-mentioned resin composition powder is molded to obtain a resin composition molded body.

[0169] (Postscript 16)

[0170] According to the method for manufacturing a resin composition molded body as described in Appendix 15, based on the measured content of at least one of the low-melting-point resin and the non-low-melting-point resin in the plastic waste, at least one of a pre-prepared powder containing a low-melting-point resin and a powder containing a non-low-melting-point resin is added to the resin composition powder, and the ratio of the content of the low-melting-point resin to the content of the non-low-melting-point resin is adjusted to reach a predetermined range to obtain a resin composition molded body, or the resin composition powder is directly molded to obtain a resin composition molded body.

[0171] Symbol Explanation

[0172] 10…Resin composition powder supply unit, 11…Crusher, 12…Magnetic separator, 13…Non-magnetic metal separator, 14…Washer, 15…Compression and volume reduction machine, 16…Pulverizer, 17…Storage tank, 18…Metering tank, 20…Wood flour supply unit, 21…Crusher, 22…Magnetic separator, 23…Pulverizer, 24…Storage tank, 25…Metering tank, 30…Low melting point resin powder supply unit, 31…Storage tank, 32…Metering tank, 40…Non-low melting point resin powder supply unit, 41…Storage tank, 42…Metering tank, 50…Additive supply unit, 51…Storage tank, 52…Metering tank, 60…Molded body manufacturing unit, 61…Mixer, 62…Storage tank, 63…Extruder, 100…Resin composition molded body manufacturing system, 200…Mold, 300…Melted material, 301…Fountain flow, 302…Flow front, 310…Surface layer

Claims

1. A method for manufacturing a molded article of a resin composition, Prepare plastic waste containing low-melting-point resin and non-low-melting-point resin with melting points above 80°C and below 190°C, wherein the non-low-melting-point resin is one or a mixture of high-melting-point resin and thermosetting resin with melting points above 190°C. The plastic waste is crushed to obtain a resin composition powder; Add at least one of a pre-prepared powder containing a low-melting-point resin and a powder containing a non-low-melting-point resin to the resin composition powder and mix them to obtain a resin composition powder mixture in which the ratio of the content of the low-melting-point resin to the content of the non-low-melting-point resin is adjusted to a predetermined range. The resin composition powder mixture is molded to obtain a molded resin composition.

2. The method for manufacturing a molded resin composition according to claim 1, wherein, The content of at least one of the low-melting-point resin and the non-low-melting-point resin in the plastic waste is determined. Based on the obtained measured values ​​of the content, adjust the amounts of the powder containing the low-melting-point resin and the powder containing the non-low-melting-point resin added to the resin composition powder.

3. The method for manufacturing a molded resin composition according to claim 2, wherein, The method for determining the content of the low-melting-point resin and the non-low-melting-point resin in the plastic waste is as follows: The sample powder obtained by crushing the plastic waste was impregnated with a heavy liquid. Measure the amount of floating matter on the surface of the heavy liquid and the amount of precipitated matter. The amount of the floating matter is taken as the content of the low-melting-point resin, and the amount of the precipitate is taken as the content of the non-low-melting-point resin.

4. The method for manufacturing a molded resin composition according to claim 3, wherein, The specific gravity of the heavy liquid is 1.08 to 1.

13.

5. The method for manufacturing a molded article of the resin composition according to claim 3 or 4, wherein, The heavy liquid is an aqueous solution of sodium chloride.

6. The method for manufacturing a molded article of resin composition according to any one of claims 1 to 5, wherein, The amounts of the powder containing the low-melting-point resin and the powder containing the non-low-melting-point resin added to the resin composition powder are adjusted such that the mass ratio of the content of the non-low-melting-point resin to the content of the low-melting-point resin in the resin composition powder mixture is in the range of 1 / 3 to 5.

7. The method for manufacturing a molded article of the resin composition according to any one of claims 1 to 6, wherein, The resin composition powder is obtained by passing it through a sieve with a mesh size of 3 mm.

8. The method for manufacturing a molded article of the resin composition according to any one of claims 1 to 7, wherein, The powder containing low-melting-point resin contains more than 60% by mass of low-melting-point resin.

9. The method for manufacturing a molded article of the resin composition according to any one of claims 1 to 8, wherein, The powder containing non-low melting point resin contains more than 60% by mass of non-low melting point resin.

10. The method for manufacturing a molded article of the resin composition according to any one of claims 1 to 9, wherein, The resin composition powder is mixed with a pre-prepared cellulose-based material powder to obtain a resin composition powder mixture containing cellulose-based material. The resin composition powder mixture containing cellulose-based materials is molded.

11. The method for manufacturing a molded article of the resin composition according to any one of claims 1 to 10, wherein, The manufacturing units for the resin composition molded articles are divided according to the type of plastic waste, and the standard deviation of the content of low-melting-point resin in the synthetic resin contained in the plastic waste used in each manufacturing unit is more than 1% by mass.

12. The method for manufacturing a molded article of the resin composition according to any one of claims 1 to 11, wherein, The resin composition is molded into a molded body by extruding the resin composition powder.

13. The method for manufacturing a molded article of the resin composition according to claim 12, wherein, The extrusion molding temperature is less than 10°C below the melting point of the non-low melting point resin contained in the resin composition powder.

14. A method for manufacturing a molded article of a resin composition, Prepare plastic waste containing low-melting-point resins and non-low-melting-point resins with melting points above 80°C and below 190°C, wherein the non-low-melting-point resins are high-melting-point resins or thermosetting resins with melting points above 190°C. The plastic waste is crushed to obtain a resin composition powder; After determining the content of at least one of the low-melting-point resin and the non-low-melting-point resin in the plastic waste, the resin composition powder is molded to obtain a molded resin composition.

15. The method for manufacturing a molded article of the resin composition according to claim 14, wherein, Based on the measured content of at least one of the low-melting-point resin and the non-low-melting-point resin in the plastic waste, a pre-prepared powder containing low-melting-point resin and a powder containing non-low-melting-point resin are added to the resin composition powder to obtain a resin composition molded body in which the ratio of the content of the low-melting-point resin to the content of the non-low-melting-point resin is adjusted to a predetermined range, or the resin composition powder is directly molded to obtain a resin composition molded body.

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