Method for producing resin composition molded body and method for producing resin composition powder for producing resin composition molded body

Abstract

A method for producing a resin composition molded body according to the present invention prepares plastic waste containing a low melting point resin having a melting point within the 80°C to less than 190°C range and a non-low melting point resin containing at least one of a high melting point resin and a thermosetting resin having a melting point of 190°C or higher, which is plastic waste containing at least one of waste plastic residue derived from general waste, waste plastic derived from industrial waste, and waste plastic derived from marine plastic waste, subjects the plastic waste or a shredded material obtained by shredding the plastic waste to treatment to remove magnetic materials and water washing treatment, obtains a resin composition powder by pulverizing the washed plastic waste or shredded material, and molds the resin composition powder to obtain a resin composition molded body.

Description

Method for producing resin composition molded body and method for producing resin composition powder for use in producing resin composition molded body

[0001] The present disclosure relates to a method for producing a resin composition molded article and a method for producing a resin composition powder for use in producing a resin composition molded article.

[0002] Woody resin composition molded articles, in which a powder of a cellulose-based material such as wood flour is dispersed in a resin, are also called wood plastics. While they have a texture similar to that of wood, they offer advantages over wood, such as resistance to corrosion, cracking, and splinters, and are lightweight. For this reason, woody resin composition molded articles are widely used as building materials and other materials. The use of low-melting-point resins, such as waste-derived polypropylene, as the resin for woody resin composition molded articles has been considered (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2001-353707

[0004] The use of plastic waste, including waste plastics, as a resin raw material for resin composition molded products promotes resource circulation and reduces CO2 emissions from incineration of waste. ２ This is desirable from the perspective of significantly contributing to the reduction of emissions. However, conventionally, only low-melting-point resins that are easily thermoformable are separated and recovered from plastic waste. Meanwhile, the waste plastic residue remaining after separating and recovering the low-melting-point resin contains a high proportion of non-low-melting-point resins, such as high-melting-point resins and thermosetting resins, making thermoforming difficult. This has led to a problem that it is difficult to utilize the waste plastic for purposes other than thermal recycling. Furthermore, the present inventors have discovered that when the plastic waste is from municipal waste, industrial waste, or marine plastic waste, the presence of inorganic matter such as magnetic substances, and organic matter such as oils and fats, food residues, and surfactants makes thermoforming difficult. Inorganic matter may damage manufacturing equipment used to produce resin composition molded products and hinder the continuous production of resin composition molded products. Organic matter may serve as a nutrient source for microorganisms such as mold and bacteria, promoting their proliferation.

[0005] The present disclosure aims to provide a method for producing a resin composition molded product that can effectively utilize plastic waste containing low-melting point resins and non-low-melting point resins, even if it contains inorganic substances such as magnetic materials or organic substances such as oils and fats, food residues, and surfactants.

[0006] The present disclosure relates to a method for producing a resin composition molded body, which comprises preparing plastic waste containing at least one of waste plastic residue derived from municipal waste, waste plastic derived from industrial waste, and waste plastic derived from marine plastic waste, the plastic waste containing a low-melting-point resin having a melting point in the range of 80°C or higher but lower than 190°C, and a non-low-melting-point resin including at least one of a high-melting-point resin and a thermosetting resin having a melting point of 190°C or higher, performing a treatment to remove magnetic substances and a water-washing treatment on the plastic waste or crushed material obtained by crushing the plastic waste, pulverizing the plastic waste or crushed material after the water-washing treatment to obtain a resin composition powder, and molding the resin composition powder to obtain a resin composition molded body.

[0007] 1 is a block diagram of a resin composition molded body manufacturing system that can be used in a method for manufacturing a resin composition molded body according to an embodiment of the present disclosure; 2 is a flow diagram of a method for manufacturing a resin composition powder for manufacturing a resin composition molded body according to an embodiment of the present disclosure; 3 is a flow diagram of a method for manufacturing a resin composition molded body according to an embodiment of the present disclosure;

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following embodiments, a woody resin composition formed body containing wood flour will be used as an example of a resin composition formed body, and a method for producing the same will be described.

[0009] 1 is a block diagram of a resin composition molded body manufacturing system that can be used in a resin composition molded body manufacturing method according to an embodiment of the present disclosure. As shown in FIG. 1, the resin composition molded 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 molded body manufacturing unit 60.

[0010] The resin composition powder supply unit 10 produces and stores resin composition powder for producing 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 washer 14, a compression volume reducer 15, a crusher 16, a storage tank 17, and a weighing tank 18.

[0011] Plastic waste includes low-melting-point resins with melting points in the range of 80°C to less than 190°C, and non-low-melting-point resins, which are mixtures of high-melting-point resins with melting points of 190°C or higher and thermosetting resins, or both. Plastic waste may also contain substances other than synthetic resins. The substances other than synthetic resins may be inorganic or organic. Examples of inorganic substances include magnetic substances, non-magnetic metals, glass, pebbles, metals, shells, sand, and other inorganic materials, as well as desiccants such as silica gel and iron-based oxygen absorbers. Examples of magnetic substances include iron, cobalt, and nickel. Examples of non-magnetic metals include aluminum. Examples of organic substances include oils and fats, food residue, and surfactants.

[0012] Examples of low-melting-point resins include polystyrene (PS), acrylonitrile-butadiene-styrene resin (ABS), polyethylene (PE), polymethyl methacrylate (PMMA), polycarbonate (PC), polypropylene (PP), polyamide 12 (PA12), and polyacetal (POM). The melting point of high-melting-point resins may be 340°C or lower. Examples of high-melting-point resins include polyethylene terephthalate (PET), polyamide 6 (PA6), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK). Thermosetting resins are resins after curing. Examples of thermosetting resins include polyimide (PI), polyurethane (PU), and phenolic resin (PF). The low-melting-point resin and non-low-melting-point resin contained in plastic waste may be one type or two or more types.

[0013] Plastic waste refers to any one or a mixture of two or more wastes including waste plastic residues from municipal waste, waste plastics from industrial waste, and waste plastics from marine plastic waste. Plastic refers to molded products made of synthetic resin. For example, plastic waste refers to waste containing 50% or more by mass of waste plastic. The waste plastic content of plastic waste may be, for example, in the range of 50% to 100% by mass, in the range of 50% to 99.5% by mass, or in the range of 50% to 70% by mass.

[0014] The ignition residue of plastic waste may be in the range of 0.5% by mass or more and 10% by mass or less. The ignition residue is a value measured, for example, by the following method. (Method for measuring ignition residue) The weight of the sample before heating is measured in a crucible. The sample is kept at 600°C for two hours in a high-temperature electric furnace to completely burn off organic components including synthetic resins. After cooling, the weight of the remaining sample is divided by the weight before heating to determine the ignition residue as a percentage.

[0015] Municipal waste refers to waste other than industrial waste and marine plastic waste, including household waste discarded from ordinary households. Examples of waste plastics derived from municipal waste include plastics used as product containers and packaging materials. Waste plastic residue is the residue remaining after separating and recovering a portion of the resins contained in waste plastic derived from municipal waste, such as the residue remaining after separating and recovering a portion of the low-melting-point resin. The low-melting-point resin to be separated and recovered may include, for example, at least one of PP, PE, and PS, or may include PP and PE. Waste plastic residue may be the residue remaining after separating and recovering 5% by mass or more of the low-melting-point resin contained in the waste plastic, or 5% by mass to 95% by mass or less, or 5% by mass to 50% by mass or less, or 5% by mass to 15% by mass or less. The sum of PP and PE may account for 20% by mass or more of the separated and recovered low-melting-point resin, or may be within the range of 50% by mass to 100% by mass, or 70% by mass to 100% by mass.

[0016] Waste plastic derived from industrial waste is waste plastic generated as a result of business activities. Examples of waste plastic derived from industrial waste include off-spec products and surplus production. Waste plastic derived from marine plastic waste is waste plastic that accumulates in the ocean when plastic products are directly dumped into the sea or when plastic products discarded on land are washed into the sea via rivers or lakes. Examples of plastic products include plastic fragments, PET bottles, fishing gear, etc. Waste plastic derived from marine plastic waste includes microplastics that are 5 mm or smaller in size due to the degradation of plastic products caused by the effects of waves and ultraviolet rays.

[0017] There are no particular restrictions on the content of low-melting-point resin and non-low-melting-point resin in the synthetic resin contained in the plastic waste. The content of low-melting-point resin may be, for example, in the range of 3% by mass to 95% by mass. The content of non-low-melting-point resin may be, for example, in the range of 5% by mass to 97% by mass. The ratio of the content of low-melting-point resin to non-low-melting-point resin (low-melting-point resin / non-low-melting-point resin) may be, for example, in the range of 1 / 3 to 5.00 by mass.

[0018] When the plastic waste is waste plastic residue, the content of the low-melting-point resin in the synthetic resin contained in the waste plastic residue may be, for example, 95% by mass or less, for example, in the range of 25% by mass to 95% by mass or less, or in the range of 35% by mass to 90% by mass or less. The total content of PE and PP relative to the total amount of low-melting-point resin may be 90% by mass or less, or in the range of 20% by mass to 80% by mass or less. The content of non-low-melting-point resin in the synthetic resin may be, for example, 5% by mass or more, or in the range of 5% by mass to 75% by mass or less, or in the range of 10% by mass to 65% by mass or less. The ratio of the content of low-melting-point resin to non-low-melting-point resin in the synthetic resin (low-melting-point resin / non-low-melting-point resin) may be, for example, in the range of 1 / 3 to 5.00 or in the range of 0.71 to 3.00 by mass. The ratio of the content of the thermosetting resin to the high-melting-point resin contained in the non-low-melting-point resin in the synthetic resin (thermosetting resin / high-melting-point resin) may be, for example, in a mass ratio range of 0.01 to 100, or may be in a range of 0.05 to 50. The content of the thermosetting resin in the synthetic resin may be, for example, 0% by mass or more, or may be in a range of 1% by mass to 10% by mass. The content of the high-melting-point resin in the synthetic resin may be, for example, 5% by mass or more, or may be in a range of 10% by mass to 90% by mass.

[0019] The form of the plastic waste is not particularly limited, and may be, for example, bale-like or block-like. When the production units (lots) of resin composition molded products are divided according to the type of plastic waste, the plastic waste used in each production unit may be generated at different locations or times. For example, the plastic waste used in each production unit may have a standard deviation of 2% by mass or more in the content of low-melting-point resin, and may be in the range of 2% by mass or more and 23% by mass or less.

[0020] The crusher 11 is a device that crushes plastic waste to obtain plastic fragments. For example, a uniaxial crusher can be used as the crusher 11. The size of the plastic fragments obtained by the crusher 11 is not particularly limited, but may be, for example, a size that passes through a sieve with a mesh size of 20 to 50 mm. The mesh size of the sieve may be 50 mm, 40 mm, or 30 mm.

[0021] The magnetic separator 12 is a device that removes and recovers magnetic materials contained in plastic pieces. As the magnetic separator 12, for example, a hanging type magnetic separator, a pulley type magnetic separator, a drum type magnetic separator, or a roll type magnetic separator can be used. Examples of magnetic materials include iron, stainless steel, and ferrite. The magnetic separator 12 may be used alone or in combination of two or more types.

[0022] The non-magnetic metal separator 13 is a device for removing and recovering non-magnetic metals contained in plastic pieces. Examples of non-magnetic metals include aluminum, copper, zinc, and brass. An eddy current separator can be used as the non-magnetic metal separator 13.

[0023] The washer 14 is a device that washes and removes deposits such as detergent, food stains, and oil stains that are attached to the plastic pieces. A wet grinding washer with a grinding function can be used as the washer 14. The wet grinding washer may be one that grinds the plastic pieces in water. For the grinding function of the plastic pieces, a grinder that has a fixed blade and a rotary blade and grinds the plastic pieces by sandwiching them between the fixed blade and the rotary blade can be used. By using the wet grinding washer to grind the plastic pieces into coarse plastic particles and wash them at the same time, it is possible to more efficiently remove deposits that are attached to the coarse plastic particles.

[0024] The compressing machine 15 is a device that compresses the coarse plastic particles to remove moisture adhering to the coarse plastic particles and reduce the volume thereof, thereby obtaining coarse plastic powder. A screw-type compressing machine equipped with a screw inside a barrel having a drainage hole can be used as the compressing machine 15. By using a screw-type compressing machine, moisture is removed by frictional heat between the screw, the barrel, and the coarse plastic particles, and a portion of the low-melting-point resin of the coarse plastic particles melts, causing the coarse plastic particles to fuse together, thereby reducing the volume of the coarse plastic particles.

[0025] The pulverizer 16 is a device that pulverizes the coarse plastic powder to produce a fine resin composition powder. The pulverizer 16 may be a fine pulverizer (cutter mill), a hammer mill, or a pin mill. The fine pulverizer (cutter mill) is equipped with a fixed blade and a rotary blade, and pulverizes plastic pieces by sandwiching them between the fixed blade and the rotary blade. The pulverizer 16 may be used alone or in combination of two or more types.

[0026] A sieve may be disposed at the outlet of the pulverizer 16 for the resin composition powder. The pulverizer 16 may be configured to retain, for example, coarse-sized coarse plastic powder inside the pulverizer 16 and discharge only the fine resin composition powder that passes through the 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 sieve mesh size may be 3 mm, 2 mm, or 1 mm. If the sieve mesh size is, for example, 500 μm or less, the heat generated by pulverizing the coarse plastic powder may melt the pulverized low-melting-point resin, and the molten resin may solidify on the surface of the sieve, which may easily cause the sieve to become clogged.

[0027] The storage tank 17 is a tank that temporarily stores the resin composition powder produced by the pulverizer 16. The measuring tank 18 is a tank that measures the resin composition powder sent from the storage tank 17 and temporarily stores a predetermined amount of the resin composition powder.

[0028] The resin composition powder supply unit 10 can produce a resin composition powder from plastic waste, for example, as follows: Fig. 2 is a flow diagram of a method for producing a resin composition powder for producing a resin composition molded article according to one embodiment of the present invention.

[0029] The method for producing the resin composition powder of this embodiment includes a crushing step S11, a magnetic substance removal step S12, a non-magnetic metal removal step S13, a water washing step S14, a volume reduction step S15, and a pulverization step S16.

[0030] The crushing step S11 is a step of crushing the plastic waste to obtain plastic pieces. The crushing step S11 is performed using a crusher 11.

[0031] The magnetic substance removal process S12 is a process for removing and recovering magnetic substances contained in plastic fragments. The magnetic substance removal process S12 is performed using a magnetic separator 12. By performing the magnetic substance removal process S12, magnetic substances mixed in the plastic fragments can be reliably removed. By removing the magnetic substances, it is possible to prevent the magnetic substances from remaining inside the crusher in the crushing process S16, which would cause wear and tear on the blades inside the crusher and gradually reduce the crushing efficiency of the crusher. In particular, by performing the magnetic substance removal process S12 after converting plastic waste into plastic fragments in the crushing process S11, molded bodies such as push-type pumps used in hand soap and shampoo containers are crushed, and metal magnetic materials such as spring materials and screw materials used in the molded bodies can be more reliably removed.

[0032] The non-magnetic metal removal process S13 is a process for removing and recovering non-magnetic metals contained in the plastic pieces. The non-magnetic metal removal process S13 is performed using a non-magnetic metal separator 13.

[0033] The water washing process S14 is a process in which the plastic pieces are crushed into coarse plastic particles while washing and removing any deposits adhering to the coarse plastic particles. The water washing process S14 is carried out using a washer 14. By carrying out the water washing process S14, it is possible to prevent adverse effects in the crushing process S16, such as organic matter such as detergent, food stains, and oil stains melting and adhering to the blades inside the crusher, which would reduce the crushing efficiency, or organic matter melting and adhering to the sieve of the crusher, which would cause the sieve to become clogged.

[0034] The volume reduction process S15 is a process for removing moisture adhering to the coarse plastic particles and reducing their volume to obtain coarse plastic powder. The volume reduction process S15 is performed using a compression volume reduction machine 15.

[0035] The pulverization step S16 is a step in which the plastic coarse powder is pulverized to obtain a resin composition powder. In the method for producing a resin composition powder of this embodiment, in the pulverization step S16, the low-melting point resin and the non-low-melting point resin contained in the plastic waste are pulverized simultaneously without being separated. The pulverization step S16 is performed using a pulverizer 16. The resin composition powder obtained by pulverization is sent to a storage tank 17.

[0036] If the plastic waste is in the form of bales or lumps, the bales or lumps may be crushed using a crusher before the crushing step S11. Furthermore, the plastic waste may contain various bulky magnetic waste items, such as batteries, lighters, spray cans, razors, and syringe needles. Therefore, the bulky magnetic waste items may be removed and collected using a magnetic separator before the crushing step S11.

[0037] The wood powder supply unit 20 produces and stores wood powder to be used as a raw material for resin composition molded bodies from waste wood. The wood powder supply unit 20 has a crusher 21, a magnetic separator 22, a grinder 23, a storage tank 24, and a measuring tank 25.

[0038] Examples of waste wood that can be used include waste construction wood, thinned wood, and sawdust.

[0039] The crusher 21 is a device that crushes waste wood to obtain wood chips. For example, a uniaxial crusher can be used as the crusher 21. The size of the wood chips obtained by the crusher 21 is not particularly limited, but may be, for example, a size that passes through a sieve with an opening of 20 to 50 mm. The opening of the sieve may be 50 mm, 40 mm, or 30 mm.

[0040] The magnetic separator 22 is a device that removes and recovers magnetic materials contained in wood pieces. As the magnetic separator 22, for example, a hanging type magnetic separator, a pulley type magnetic separator, a drum type magnetic separator, or a roll type magnetic separator can be used. Examples of magnetic materials include nails and bolts. The magnetic separator 22 may be used alone or in combination of two or more types.

[0041] The crusher 23 is a device that crushes wood pieces to generate fine wood powder. A fine crusher (cutter mill), a hammer mill, or a pin mill can be used as the crusher 23. One type of crusher 23 may be used alone, or two or more types may be used in combination.

[0042] A sieve may be provided at the wood powder outlet of the pulverizer 23. The pulverizer 16 may be configured to retain, for example, coarse-sized plastic coarse powder inside the pulverizer 16 and discharge only the fine resin composition powder that passes through the sieve to the outside. As the sieve, for example, a sieve with a mesh size in the range of 300 μm to 3 mm can be used. The sieve mesh size may be 2 mm, 1 mm, or 500 μm.

[0043] The storage tank 24 is a tank that temporarily stores the wood powder generated by the crusher 23. The measuring tank 25 is a tank that measures the wood powder sent from the storage tank 24 and temporarily stores a predetermined amount of wood powder.

[0044] The low-melting-point resin powder supplying section 30 stores the low-melting-point resin powder to be used as a raw material for the resin composition molded article as needed. The low-melting-point resin powder supplying section 30 has a storage tank 31 and a measuring tank 32.

[0045] The low-melting point resin powder includes a low-melting point resin. Examples of low-melting point resins include PS, ABS, PE, PMMA, PC, PP, PA12, and POM. The low-melting point resins may be used alone or in combination. The low-melting point resin powder may also include a non-low-melting point resin. The low-melting point resin content of the low-melting point resin powder may be, for example, 60% by mass or more, or 80% by mass or more. The low-melting point resin powder may be obtained by crushing plastic waste containing 60% by mass or more of a low-melting point resin. The low-melting point resin powder may be one that passes through a sieve with a mesh size of 3 mm. For example, waste materials such as shrink film (PE), cable ties (PP), and polystyrene foam (PS) that have been used for packaging, bundling, and curing products and crushed to 3 mm or less can be used as the low-melting point resin powder. In addition, recycled plastics (PP, PE, PS) collected and produced in accordance with the Containers and Packaging Recycling Law can also be crushed to 3 mm or less.

[0046] The storage tank 31 is a tank for temporarily storing the low-melting-point resin powder. The measuring tank 32 is a tank for measuring the low-melting-point resin powder sent from the storage tank 31 and temporarily storing a predetermined amount of the low-melting-point resin powder.

[0047] The non-low melting point resin powder supply unit 40 stores the non-low melting point resin powder used as a raw material for the resin composition molded article as needed. The non-low melting point resin powder supply unit 40 has a storage tank 41 and a measuring tank 42.

[0048] The non-low melting point resin powder includes a non-low melting point resin. Examples of the non-low melting point resin include PET, PA6, PBT, PPS, PEEK, PI, PU, ​​and PF. The non-low melting point resin may be used alone or in combination of two or more. The non-low melting point resin powder may contain a non-low melting point resin. The content of the non-low melting point resin in the non-low melting point resin powder may be, for example, 60% by mass or more, or 80% by mass or more. The non-low melting point resin powder may be obtained by crushing plastic waste containing 60% by mass or more of a non-low melting point resin. The non-low melting point resin powder may be one that passes through a sieve with a mesh size of 3 mm. Recycled materials such as PET waste used as egg containers or food packaging materials crushed to 3 mm or less can be used as the non-low melting point resin powder.

[0049] The storage tank 41 is a tank for temporarily storing the non-low melting point resin powder. The measuring tank 42 is a tank for measuring the non-low melting point resin powder sent from the storage tank 41 and temporarily storing a predetermined amount of the non-low melting point resin powder.

[0050] The additive supply unit 50 stores additives to be added to the resin composition molded article as desired. The additive supply unit 50 includes a storage tank 51 and a measuring tank 52.

[0051] Additives that can be used include various additives commonly used in conventional resin composition molded products, such as pigments, compatibilizers for improving the affinity between the resin and wood flour, fillers, lubricants, weathering agents, heat stabilizers, foaming agents, and antistatic agents. Pigments are used to color the resin composition molded product. Examples of pigments that can be used include inorganic pigments, organic pigments, and mixtures thereof. Compatibilizers are used to increase the adhesion between the wood flour and the resin component, improving the strength and water resistance of the resin composition molded product. Examples of compatibilizers that can be used include maleic anhydride-modified polypropylene compatibilizers. Lubricants are added to improve the sliding properties with the mold. Examples of lubricants that can be used include oxidized polyolefin wax, acid-modified polyolefin wax, calcium stearate, and zinc stearate. Examples of weathering agents that can be used include ultraviolet absorbers (UVA), light absorbers (HALS), and antioxidants.

[0052] The storage tank 51 is a tank for temporarily storing the additive. The metering tank 52 is a tank for measuring the additive sent from the storage tank 51 and temporarily storing a predetermined amount of the additive. The storage tank 51 and the metering tank 52 may be provided one for each type of additive, or one for an additive mixture containing two or more types of additives.

[0053] The molded body production section 60 produces a resin composition molded body. The molded body production section 60 includes a mixer 61, a storage tank 62, and an extruder 63.

[0054] The mixer 61 is a device that mixes a resin composition powder, which is a raw material for the resin composition molded body, at least one of a low-melting-point resin-containing powder and a non-low-melting-point resin-containing powder, wood flour, and additives to obtain a raw material mixture. A heater mixer, for example, can be used as the mixer 61. By using the heater mixer to mix the raw materials while heating, a mixture in which the raw materials are uniformly dispersed can be obtained. The heating temperature of the heater mixer varies depending on the resins contained in the raw material mixture, but may be in the range of 100 to 150°C, for example, when the resin with the lowest melting point is PE.

[0055] The storage tank 62 is a tank for temporarily storing the raw material mixture, and supplies a predetermined amount of the raw material mixture to the extruder 63.

[0056] The extruder 63 is a device that molds the raw material mixture into a predetermined shape. Examples of the extruder 63 that can be used include a single-screw extruder and a twin-screw extruder. The molding temperature of the extruder 63 varies depending on factors such as the type and content of the low-melting-point resin contained in the raw material mixture, but is, for example, 150°C or higher when PE is included. On the other hand, wood flour decomposes and gasifies at temperatures above 190°C, which can cause bubbles to form in the resin composition molded product, so the molding temperature is preferably below 190°C.

[0057] Next, a method for producing a resin composition molded product using the resin composition molded product production system 100 will be described. Fig. 3 is a flow diagram of the method for producing a resin composition molded product according to one embodiment of the present disclosure. The method for producing a resin composition molded product according to this embodiment includes an analysis step S21, a mixing step S22, and a molding step S23.

[0058] The analysis step S21 is a step of analyzing the composition of the resin composition powder. The ratio of the content of the low-melting point resin to the content of the non-low-melting point resin in the resin composition powder can be used as the composition of the resin composition powder. The resin composition powder (sample powder) to be analyzed may be, for example, the resin composition powder stored in the storage tank 17 of the resin composition powder supply unit 10.

[0059] The content of low-melting-point resin and non-low-melting-point resin in a resin composition powder can be analyzed by, for example, separating the low-melting-point resin and the non-low-melting-point resin using the difference in specific gravity between them and measuring the content of each separated resin. In this embodiment, the analysis was performed as follows: The resin composition powder was immersed in an aqueous sodium chloride solution as a sample powder. Next, the amount of floating matter rising to the surface of the sodium chloride solution and the amount of sediment that settled were measured. The floating matter was scooped out of the aqueous sodium chloride solution. The sediment was recovered by filtering the aqueous sodium chloride solution after all the floating matter had been scooped out. The recovered floating matter and sediment were washed with water and then dried, and the amounts of the floating matter and sediment were measured. The amount of floating matter was determined as the content of the low-melting-point resin, and the amount of sediment was determined as the content of the non-low-melting-point resin. The specific gravity of the aqueous sodium chloride solution can be, for example, 1.08 to 1.13.

[0060] The mixing step S22 is a step of obtaining a raw material mixture by mixing the resin composition powder, at least one of a low-melting-point resin-containing powder and a non-low-melting-point resin-containing powder, wood flour, and additives. The mixing step S22 is performed by mixing the raw materials sent from the measuring tanks 18, 25, 32, 42, and 52 using a mixer 61. The obtained raw material mixture is sent to a storage tank 62.

[0061] In the mixing step S22, the mixing ratio of the resin composition powder and the melting point resin-containing powder and / or the non-low melting point resin-containing powder is adjusted based on the ratio of the low melting point resin content to the non-low melting point resin content of the resin composition powder obtained in the analysis step S21. The total content of the low melting point resin and the non-low melting point resin in the raw material mixture obtained in the mixing step S22 may be, for example, in the range of 50 to 90 mass%. The wood flour content may be, for example, in the range of 5 to 40 mass%. The additive content may be, for example, in the range of 5 to 40 mass%. Furthermore, the ratio of the low melting point resin content to the non-low melting point resin content of the resin composition powder mixture may be, by mass, in the range of 1 / 3 to 5, or in the range of 1 / 3 to 1.40.

[0062] The molding step S23 is a step in which the raw material mixture obtained in the mixing step S22 is molded to obtain a wood resin composition molded body. The molding step S23 is performed by extruding the raw material mixture sent from the storage tank 62 using an extruder 63. By extrusion molding, the low-melting-point resin in the resin composition powder melts, resulting in a wood resin composition molded body in which a non-low-melting-point resin and wood flour are dispersed in the low-melting-point resin. There are no particular restrictions on the shape of the wood resin composition molded body, and it may be, for example, a plate-like shape.

[0063] In the molding step S23, the non-low melting point resin is not melted but left unmelted, so that the non-low melting point resin is dispersed in an island-like manner in the molded body and behaves like 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 has a sea-like and low elastic modulus. Therefore, the resin composition molded body as a whole has high elasticity and strength. From the viewpoint of improving the elasticity and strength of the resin composition molded body, it is preferable that the resin composition powder is fine, and more preferably, it has passed through a sieve with a mesh size of 1 mm.

[0064] The woody resin composition formed body obtained as described above contains wood flour and has a texture similar to that of wood, so it can be used as a wood substitute. The resin composition formed body can be used, for example, as a civil engineering material, a building material, or a gardening material. Examples of civil engineering materials include paving materials. Examples of building materials include flooring materials, particularly bathroom flooring materials, roofing materials, wall materials, handrails, sashes, wood decks, fences, etc. Examples of gardening materials include flower beds.

[0065] In the method for producing a resin composition molded product of this embodiment configured as described above, plastic waste containing a low-melting point resin and a non-low-melting point resin is crushed in a crushing step S11 to obtain crushed material, and the crushed material is then subjected to a magnetic substance removal process S12, a non-magnetic metal removal process S13, and a water washing process S14, followed by a pulverization process S16, thereby efficiently removing inorganic matter, oils and fats, food residues, surfactants, and other organic matter mixed in the plastic waste. Therefore, according to the method for producing a resin composition molded product of this embodiment, a resin composition molded product can be produced industrially and stably using plastic waste containing a low-melting point resin and a non-low-melting point resin.

[0066] In the method for producing a resin composition molded product of this embodiment, by using a fine pulverizer (cutter mill) as the pulverizer 16 in the pulverization step S16, it is possible to industrially produce a resin composition powder derived from plastic waste more efficiently. Furthermore, in the method for producing a resin composition molded product of this embodiment, if the resin composition powder derived from plastic waste has been passed through a sieve with a mesh size of 3 mm, the non-low melting point resin is fine, so that the non-low melting point resin can be coated with a molten low melting point resin during the production of the resin composition molded product. This further improves the water resistance of the resulting resin composition molded product. Furthermore, in the method for producing a resin composition molded product of this embodiment, after the water washing treatment step S14, a compression volume reducer 15 is used in the volume reduction treatment step S15 to remove moisture and fuse plastic coarse particles together to reduce the volume, thereby improving the pulverization efficiency in the pulverization step S16.

[0067] In the method for producing a resin composition molded article of this embodiment, when waste plastic residue derived from municipal waste is used as the plastic waste, the resin composition of the waste plastic residue is prone to change. Therefore, when using a resin composition powder derived from waste plastic residue, at least one of a low-melting-point resin-containing powder and a non-low-melting-point resin-containing powder prepared in advance may be added and mixed to obtain a resin composition powder mixture, which may then be molded. This allows the contents of the low-melting-point resin and non-low-melting-point resin in the resin composition powder mixture to be adjusted, thereby enabling the stable production of resin composition molded articles.

[0068] In the method for producing a resin composition molded product of this embodiment, when the low-melting point resin-containing powder added to the resin composition powder derived from plastic waste contains 60% by mass or more of the low-melting point resin, the low-melting point resin content of the low-melting point resin-containing powder is high, so that when the resin composition powder contains a small amount of low-melting point resin, it is easy to adjust the amount of the low-melting point resin-containing powder added. Also, in the method for producing a resin composition molded product of this embodiment, when the non-low-melting point resin-containing powder added to the resin composition powder derived from plastic waste contains 60% by mass or more of the non-low-melting point resin, the non-low-melting point resin content of the non-low-melting point resin-containing powder is high, so that when the resin composition powder contains a small amount of non-low-melting point resin, it is easy to adjust the amount of the non-low-melting point resin-containing powder added.

[0069] In the method for producing a resin composition molded article of this embodiment, wood flour is added to and mixed with a resin composition powder derived from plastic waste to obtain a wood-flour-containing resin composition powder mixture, and the wood flour-containing resin composition powder mixture is molded to obtain a resin composition molded article having a texture similar to that of wood. A cellulose-based material powder such as pulp powder can be used instead of wood flour. The particle size of the wood flour correlates with the water resistance of the resulting resin composition molded article, and finer wood flour particle size tends to improve the water resistance of the resin composition molded article. From the perspective of improving the water resistance of the resin composition molded article, the wood flour is preferably passed through a sieve with a mesh size in the range of 300 μm to 3 mm, and more preferably passed through a sieve with a mesh size of 500 μm.

[0070] In the method for producing a resin composition powder for producing a resin composition molded product of this embodiment, plastic waste is crushed in a crushing step S11 to obtain crushed material, and the crushed material is then subjected to a magnetic substance removal treatment step S12, a non-magnetic metal removal treatment step S13, and a water washing treatment step S14, followed by pulverization, so that inorganic matter, oils and fats, food residues, surfactants, and other organic matter mixed in the plastic waste can be efficiently removed. Therefore, according to the method for producing a resin composition powder of this embodiment, a resin composition powder that can be used for producing a resin composition molded product can be industrially and stably produced using waste plastic residues derived from municipal waste or waste plastics derived from industrial waste.

[0071] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited thereto. For example, in this embodiment, plastic waste is crushed in the crushing step S11, but the crushing step S11 may be omitted depending on the shape of the plastic waste. In this embodiment, non-magnetic metals contained in the plastic fragments are removed and recovered in the non-magnetic metal removal treatment step S13, but the non-magnetic metal removal treatment step S13 may be omitted, for example, if the amount of non-magnetic metal contained in the plastic fragments is small. In the method for producing a resin composition powder of this embodiment, the plastic coarse particles after washing in the water washing treatment step S14 are reduced in volume in the volume reduction treatment step S15, but the washed plastic coarse particles may be crushed in the crushing step S16 without being reduced in volume.

[0072] In this embodiment, the content of the low-melting point resin and the non-low-melting point resin in the resin composition powder derived from plastic waste is measured in the analysis step S21, but the analysis step S21 is not an essential component. For example, if the content of the low-melting point resin and the non-low-melting point resin in the plastic waste is known, the analysis step S21 may be omitted. Furthermore, in this embodiment, the content of the low-melting point resin and the non-low-melting point resin in the resin composition powder is measured in the analysis step S21. However, it is also possible to measure only the low-melting point resin and subtract the content of the low-melting point resin from the content of the resin composition powder to determine the content of the non-low-melting point resin, or to measure only the non-low-melting point resin and subtract the content of the non-low-melting point resin from the content of the resin composition powder to determine the content of the low-melting point resin. Furthermore, in this embodiment, the content of the low-melting point resin and the non-low-melting point resin in the resin composition powder is measured using the difference in specific gravity in the analysis step S21, but the measurement method is not limited thereto. For example, DSC (differential scanning calorimetry), GC-MS (gas chromatography-mass spectrometry), infrared absorption spectroscopy, or elemental analysis (CHN coder) may be used. When DSC is used, the content of the non-low melting point resin may be measured, and the amount obtained by subtracting the content of the non-low melting point resin from the content of the resin composition powder may be used as the content of the low melting point resin.

[0073] In this embodiment, the molding step S23 is performed by extrusion molding, but the molding method for the resin composition molded body is not limited to this. The molding method for the resin composition molded body may be any method that melts the low-melting-point resin of the resin composition powder to form a molten resin composition. The molding method for the resin composition molded body may be, for example, injection molding, press molding, cast molding, or laminate molding using a 3D printer.

[0074] In this embodiment, the coarse plastic powder is crushed in crusher 16, and the wood chips are crushed in crusher 23. However, the coarse plastic powder and the wood chips may be crushed simultaneously using the same crusher to produce a powder mixture containing a resin composition powder and wood flour. While the resin composition molded body has been described using a wood-based resin composition molded body containing wood flour as an example, it does not have to contain wood flour, as long as it contains a resin composition powder derived from plastic waste. Furthermore, in this embodiment, waste wood is used as the raw material for the wood flour, but the raw material for the wood flour is not limited to waste wood.

[0075] The present disclosure will be described in more detail below based on examples. The present disclosure is not limited to these examples. In these examples, waste plastics 1 and 2 were used, each containing the amounts of low-melting point resin and non-low-melting point resin shown in Table 1 below. Waste plastics 1 and 2 were waste plastic residues derived from general waste.

[0076]

[0077] Example 1 (Production of Resin Composition Powder) Waste 1 was placed in a crusher and crushed. The crushed material obtained was passed through a high-magnetic pulley-type magnetic separator with a magnetic force of 2000 Gauss on the belt surface to remove iron-containing materials. Next, the crushed material from which the iron-containing materials had been removed was crushed in a uniaxial coarse crusher until it passed through a 50 mm mesh sieve, thereby obtaining plastic fragments (crushing step). The magnetic materials contained in the obtained plastic fragments were removed and recovered using a hanging magnetic separator and a pulley-type magnetic separator (magnetic material removal processing step). Next, non-magnetic metals contained in the plastic fragments were removed and recovered using a non-magnetic metal separator (non-magnetic metal removal processing step). Next, the deposits adhering to the plastic fragments were washed while being crushed using a wet crushing and washing machine until they passed through a 12 mm mesh sieve, thereby obtaining coarse plastic particles (water washing processing step). Next, the coarse plastic particles obtained in the wet grinding and washing machine were compressed and dehydrated using a volume reduction and compression dehydrator to reduce the volume, resulting in a coarse plastic powder with a moisture content of 0.5% by mass (volume reduction process). Finally, the coarse plastic powder was pulverized using a cutter mill-type pulverizer until it passed through a sieve with 2 mm openings (pulverization process). In this way, a resin composition powder was obtained. The presence or absence of the magnetic substance removal process, non-magnetic metal removal process, water washing process, and volume reduction process, and the opening diameter of the sieve used in the pulverization process are shown in Table 2 below.

[0078] In the grinding process, the long-term stability of the processing capacity of the cutter mill type grinder was evaluated by the following method, and the results are shown in Table 2 below.

[0079] (Long-term stability of processing capacity) The pulverization process was carried out continuously for 12 hours, and the degree of decrease in pulverization processing capacity was evaluated. The raw materials were fed into the cutter mill-type pulverizer while adjusting the current value of the main shaft motor of the pulverizer to be constant. The weight of the resin composition powder obtained in the 30 minutes from 30 minutes after the start of operation to 1 hour after the start of operation was defined as the initial processing amount. The weight of the resin composition powder obtained in the 30 minutes from 11 hours 30 minutes after the start of operation to 12 hours after the start of operation was measured, and the obtained weight was converted into a percentage of the initial processing amount, and the obtained value was defined as the processing capacity maintenance rate. A processing capacity maintenance rate of 90% or more was defined as "A," a rate of 70% or more but less than 90% was defined as "B," and a rate of less than 70% was defined as "C." The blades of the cutter mill-type pulverizer were re-sharpened for each Example and Comparative Example and used for evaluation.

[0080] (Production of wood flour) Waste wood was fed into a crusher and crushed using a uniaxial coarse crusher until it passed through a sieve with 50 mm openings, obtaining wood chips (crushing process). Magnetic materials contained in the obtained wood chips were removed and recovered using a hanging magnetic separator and a pulley magnetic separator (magnetic material removal process). Next, the wood chips were crushed using a cutter mill-type crusher until they passed through a sieve with 1 mm openings (crushing process). In this way, wood powder was obtained. The opening diameters of the sieves used in the crushing process are shown in Table 2 below.

[0081] (Method for producing resin composition molded body) 60 parts by mass of resin composition powder, 30 parts by mass of wood powder, and 10 parts by mass of additives (a mixture containing a pigment, a compatibilizer, an inorganic filler, a lubricant, and a weathering material) were mixed at 150 ° C using a heat mixer. The resulting mixture was molded using an extruder with a rectangular cross-sectional mold 30 mm thick and 300 mm wide to obtain a plate-shaped resin composition molded body. The composition of the obtained resin composition molded body is shown in Table 3 below.

[0082] The resulting molded resin composition articles were evaluated for bending strength, water resistance, and mildew resistance by the following methods, and the results are shown in Table 3 below.

[0083] (Bending strength) Bending strength (three-point bending) is measured using a full-scale test specimen in accordance with Method B specified in JIS A 5741:2016 (recycled wood-plastic composite material). Bending strength of 20 MPa or more is rated as "S", 15 MPa or more but less than 20 MPa is rated as "A", 10 MPa or more but less than 15 MPa is rated as "B", and less than 10 MPa is rated as "C".

[0084] (Water Resistance) The sample is immersed in warm water adjusted to 60°C. The sample is taken out of the warm water every day and the thickness of the sample is measured. The change rate of the thickness of the sample from the previous day is calculated using the following formula (1): Change rate of sample thickness (%) = (sample thickness - sample thickness on the previous day) / sample thickness on the previous day x 100 (1)

[0085] When the change in thickness of the sample becomes 0.5% or less, it is assumed that the expansion rate of the sample's thickness due to water absorption has reached equilibrium, and the equilibrium expansion rate of the sample's thickness is calculated using the following formula (2). The sample thickness was determined as the average of the thicknesses at five locations: the center of the plane and the areas near each of the four corners. Equilibrium expansion rate (%) = {(Tf - Ti) / Ti} × 100 (2) In formula (2), Tf (unit: mm) is the thickness of the resin composition molded article when the change in thickness becomes 0.5% or less, and Ti (unit: mm) is the thickness of the resin composition molded article before immersion in warm water. Water resistance is evaluated as "S" when the equilibrium expansion rate is 5% or less, "A" when it is 10% or less, "B" when it is more than 10% and 20% or less, and "C" when it is more than 20%.

[0086] (Mold resistance) According to Method A specified in Appendix A (Testing of plastic products) of JIS Z 2911:2018 (Mold resistance test method), the area of ​​the sample on which mycelia have grown after two weeks is measured. Mold resistance is rated as "A" if the growth area is less than 25%, "B" if it is 25% or more but less than 50%, and "C" if it is 50% or more.

[0087] Examples 2 to 8, Comparative Examples 1 to 3 Resin composition powders and wood flour were produced in the same manner as in Example 1, except that the conditions for producing the resin composition powder and the wood flour were changed as shown in Table 2, and resin composition molded articles were produced using the obtained resin composition powders and wood flour. Table 2 shows the processing capacity and long-term stability of the pulverizer used in producing the resin composition powder, and Table 3 shows the bending strength, water resistance, and mold resistance of the obtained resin composition molded articles.

[0088]

[0089]

[0090] The results shown in Tables 2 and 3 demonstrate that resin composition molded articles with excellent bending strength, water resistance, and mold resistance can be obtained by using the resin composition powders obtained in Examples 1 to 8, which were subjected to the magnetic material removal treatment, non-magnetic metal removal treatment, water washing treatment, and volume reduction treatment. In particular, the resin composition molded articles obtained in Example 2, in which the sieve used in the pulverizer to produce the resin composition powder had a mesh size of 1 mm, and Example 8, in which the sieve used in the pulverizer to produce the resin composition powder had a mesh size of 500 μm, exhibited improved bending strength. This is because the use of resin composition powder that passed through a sieve with a mesh size of 1 mm or 500 μm resulted in the dispersion of fine, non-low-melting-point resin particles in the resin composition molded article in an island-like pattern. These results demonstrate that, from the perspective of bending strength of the resin composition molded article, it is preferable for the resin composition powder to be fine, i.e., to be finely pulverized. On the other hand, pulverizing the resin composition powder finely tends to reduce the long-term stability of the pulverizer's processing capacity, and it is therefore preferable to use a sieve with a mesh size of 1 mm or more in the case of a cutter mill-type pulverizer. Furthermore, the resin composition molded product obtained in Example 4, in which the sieve used in the mill to produce the wood flour had a mesh size of 500 μm, had improved water resistance. This is because the use of fine wood flour that passed through a sieve with a mesh size of 500 μm as the wood flour, which is a water absorption factor in the water resistance test, allows the wood flour to be efficiently mixed and dispersed in the low-melting-point resin, thereby suppressing the change in water absorption of the resin composition molded product.

[0091] In contrast, Comparative Example 1, in which the water-washing treatment step and the volume-reducing treatment step were not performed, exhibited a decrease in the long-term stability of the crusher's processing capacity. This was because organic matter such as detergent, food stains, and oil stains was not removed and mixed into the crusher, melting and adhering to the cutters inside the crusher, reducing the crushing efficiency, and the organic matter melting and adhering to the crusher's sieve, clogging it. Furthermore, the resin composition molded body obtained in Comparative Example 1 exhibited a decrease in water resistance. This was due to the incorporation of organic matter into the resin composition molded body. Comparative Example 2, in which the magnetic substance removal treatment step and the non-magnetic metal removal treatment step were not performed, exhibited a decrease in the long-term stability of the crusher's processing capacity. This was due to the magnetic substances and non-magnetic metals not being removed and mixing into the crusher, causing wear on the cutters inside the crusher. Comparative Example 3, in which the magnetic substance removal treatment step, non-magnetic metal removal treatment step, water-washing treatment step, and volume-reducing treatment step were not performed, exhibited a significant decrease in the long-term stability of the crusher's processing capacity. This is because organic matter, magnetic materials and non-magnetic metals were not removed and were mixed in the grinder.

[0092] The following additional notes apply to aspects of the present disclosure: (Additional Note 1) A method for producing a resin composition molded body, comprising: preparing plastic waste containing at least one of waste plastic residue derived from municipal waste, waste plastic derived from industrial waste, and waste plastic derived from marine plastic waste, the plastic waste containing a low-melting-point resin having a melting point in the range of 80°C to less than 190°C, and a non-low-melting-point resin containing at least one of a high-melting-point resin and a thermosetting resin having a melting point of 190°C or more; subjecting the plastic waste or crushed material obtained by crushing the plastic waste to a treatment for removing magnetic substances and a water-washing treatment; pulverizing the plastic waste or the crushed material after the water-washing treatment to obtain a resin composition powder; and molding the resin composition powder to obtain a resin composition molded body.

[0093] (Appendix 2) The method for producing a resin composition molded article according to Appendix 1, wherein the ignition residue of the plastic waste is in the range of 0.5% by mass to 10% by mass.

[0094] (Appendix 3) The method for producing a resin composition molded body according to Appendix 1 or 2, wherein the content of the low-melting point resin in the synthetic resin contained in the waste plastic residue derived from municipal waste and the waste plastic derived from marine plastic waste is 95% by mass or less, and the content of the non-low-melting point resin in the synthetic resin is 5% by mass or more.

[0095] (Appendix 4) The method for producing a resin composition molded body according to any one of Appendices 1 to 3, wherein the waste plastic residue derived from municipal waste is a residue remaining after separating and recovering a portion of a low-melting point resin contained in the waste plastic contained in the municipal waste.

[0096] (Appendix 5) The method for producing a resin composition molded body according to Appendix 4, wherein the waste plastic residue derived from municipal waste is the residue remaining after separating and recovering 5% by mass or more of the low-melting point resin contained in the waste plastic contained in the municipal waste.

[0097] (Appendix 6) The method for producing a resin composition molded body according to any one of Appendices 1 to 5, wherein the waste plastic residue derived from municipal waste contains at least one of polyethylene and polypropylene, and the total content of the polyethylene and polypropylene relative to the total amount of the low-melting point resin is 90 mass% or less.

[0098] (Appendix 7) The method for producing a resin composition molded body according to any one of Appendices 1 to 6, wherein the content of the high-melting point resin in the synthetic resin contained in the waste plastic residue derived from municipal waste is in the range of 10% by mass or more and 90% by mass or less.

[0099] (Appendix 8) The method for producing a resin composition molded body according to any one of Appendices 1 to 7, wherein the content of the thermosetting resin in the synthetic resin contained in the waste plastic residue derived from municipal waste is in the range of 0% by mass or more and 20% by mass or less.

[0100] (Appendix 9) The method for producing a resin composition molded body according to any one of Appendices 1 to 8, wherein the ratio of the content of the thermosetting resin to the high-melting point resin in the waste plastic residue derived from municipal waste is in the range of 0.01 or more and 100 or less in mass ratio.

[0101] (Appendix 10) The method for producing a resin composition molded body according to any one of Appendices 1 to 9, wherein the production units of the resin composition molded body are divided according to the type of the plastic waste, and the standard deviation of the content of the low-melting point resin in the plastic waste used in each production unit is 2 mass% or more.

[0102] (Appendix 11) The method for producing a resin composition molded article according to any one of Appendices 1 to 10, wherein the magnetic substance removal treatment is carried out on crushed material obtained by crushing the plastic waste.

[0103] (Appendix 12) The method for producing a resin composition molded article according to any one of Appendices 1 to 11, wherein a treatment for removing non-magnetic metals is carried out between the treatment for removing the magnetic material and the water washing treatment.

[0104] (Appendix 13) The method for producing a resin composition molded article according to any one of Appendices 1 to 12, wherein the crushed material is crushed using a fine crusher.

[0105] (Appendix 14) The method for producing a resin composition molded product according to any one of Appendices 1 to 13, wherein the crushed material is pulverized under conditions that allow the resin composition powder to pass through a sieve with a mesh size of 3 mm.

[0106] (Appendix 15) The method for producing a resin composition molded article according to any one of Appendices 1 to 14, wherein the resin composition molded article is molded by extrusion molding the resin composition powder.

[0107] (Appendix 16) The method for producing a resin composition molded body according to any one of Appendices 1 to 15, wherein the crushed material after the water washing treatment is dehydrated using a compression reducer, and the crushed material after the dehydration treatment is pulverized.

[0108] (Appendix 17) The method for producing a resin composition molded product according to any one of Appendices 1 to 16, further comprising: adding at least one of a low-melting-point resin-containing powder and a non-low-melting-point resin-containing powder, which have been prepared in advance, to the resin composition powder and mixing them to obtain a resin composition powder mixture; and molding the resin composition powder mixture.

[0109] (Appendix 18) The method for producing a resin composition molded article according to any one of Appendices 1 to 17, wherein the low-melting-point resin-containing powder contains 60 mass % or more of a low-melting-point resin.

[0110] (Appendix 19) The method for producing a resin composition molded article according to any one of Appendices 1 to 18, wherein the non-low melting point resin-containing powder contains 60 mass % or more of a non-low melting point resin.

[0111] (Appendix 20) A method for producing a resin composition molded body according to any one of Appendices 1 to 19, comprising adding a cellulose-based material powder prepared in advance to the resin composition powder and mixing them to obtain a cellulose-based material-containing resin composition powder mixture, and molding the cellulose-based material-containing resin composition powder mixture.

[0112] (Appendix 21) The method for producing a resin composition molded product according to any one of Appendices 1 to 20, wherein the resulting resin composition molded product has a bending strength of 20 MPa or more as measured in accordance with Method B specified in JIS A 5741:2016.

[0113] (Appendix 22) The method for producing a resin composition molded product according to any one of Appendices 1 to 21, wherein the area of ​​the mycelium-grown portion of the obtained resin composition molded product after two weeks, as measured by Method A specified in Appendix A of JIS Z 2911:2018, is less than 25% of the total area.

[0114] (Appendix 23) A method for producing a resin composition powder for use in producing a resin composition molded product, comprising: preparing plastic waste containing at least one of waste plastic residue derived from municipal waste, waste plastic derived from industrial waste, and waste plastic derived from marine plastic waste, the plastic waste containing a low-melting-point resin having a melting point in the range of 80°C or higher but lower than 190°C, and a non-low-melting-point resin containing one or both of a high-melting-point resin having a melting point of 190°C or higher and a thermosetting resin; subjecting the plastic waste or crushed material obtained by crushing the plastic waste to a treatment for removing magnetic substances and a water-washing treatment; and pulverizing the plastic waste or the crushed material after the water-washing treatment to obtain a resin composition powder.

[0115] 10...resin composition powder supply section, 11...crusher, 12...magnetic separator, 13...non-magnetic metal separator, 14...washer, 15...compression volume reducer, 16...crusher, 17...storage tank, 18...measuring tank, 20...wood powder supply section, 21...crusher, 22...magnetic separator, 23...crusher, 24...storage tank, 25...measuring tank, 30...low melting point resin powder supply section, 31...storage tank, 32...measuring tank, 40...non-low melting point resin powder supply section, 41...storage tank, 42...measuring tank, 50...additive supply section, 51...storage tank, 52...measuring tank, 60...molded body production section, 61...mixer, 62...storage tank, 63...extruder, 100...resin composition molded body production system

Claims

1. A method for producing a resin composition molded body, comprising the steps of: preparing plastic waste containing at least one of waste plastic residues derived from general waste, waste plastics derived from industrial waste, and waste plastics derived from marine plastic waste, the plastic waste containing a low-melting point resin having a melting point in the range of 80°C to 190°C, and a non-low-melting point resin containing at least one of a high-melting point resin and a thermosetting resin having a melting point of 190°C or higher; performing a process for removing magnetic substances and a water-washing process on the plastic waste or crushed material obtained by crushing the plastic waste; pulverizing the plastic waste or the crushed material after the water-washing process to obtain a resin composition powder; and molding the resin composition powder to obtain a resin composition molded body.

2. The method for producing a resin composition molded product according to claim 1, wherein the ignition residue of the plastic waste is in the range of 0.5% by mass or more and 10% by mass or less.

3. A method for producing a resin composition molded body described in claim 1 or 2, wherein the content of the low melting point resin in the synthetic resin contained in the waste plastic residue derived from general waste and the waste plastic derived from marine plastic waste is 95 mass% or less, and the content of the non-low melting point resin in the synthetic resin is 5 mass% or more.

4. A method for producing a resin composition molded body described in any one of claims 1 to 3, wherein the waste plastic residue derived from general waste is a residue remaining after separating and recovering a portion of the low-melting point resin contained in the waste plastic contained in the general waste.

5. A method for producing a resin composition molded body as described in claim 4, wherein the waste plastic residue derived from the general waste is the residue remaining after separating and recovering 5% by mass or more of the low-melting point resin contained in the waste plastic contained in the general waste.

6. A method for producing a resin composition molded body described in any one of claims 1 to 5, wherein the waste plastic residue derived from general waste contains at least one of polyethylene and polypropylene, and the total content of the polyethylene and polypropylene relative to the total amount of the low melting point resin is 90 mass% or less.

7. A method for producing a resin composition molded body described in any one of claims 1 to 6, wherein the content of the high melting point resin in the synthetic resin contained in the waste plastic residue derived from general waste is in the range of 10 mass% or more and 90 mass% or less.

8. A method for producing a resin composition molded body described in any one of claims 1 to 7, wherein the content of the thermosetting resin in the synthetic resin contained in the waste plastic residue derived from general waste is in the range of 0 mass% or more and 20 mass% or less.

9. A method for producing a resin composition molded body described in any one of claims 1 to 8, wherein the ratio of the content of the thermosetting resin to the high melting point resin in the waste plastic residue derived from general waste is in the range of 0.01 or more and 100 or less in mass ratio.

10. A method for producing a resin composition molded body described in any one of claims 1 to 9, wherein the production units of the resin composition molded body are divided according to the type of the 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 production unit is 2 mass% or more.

11. A method for producing a resin composition molded product according to any one of claims 1 to 10, wherein the magnetic substance removal treatment is carried out on crushed material obtained by crushing the plastic waste.

12. A method for producing a resin composition molded article according to any one of claims 1 to 11, further comprising a step of removing non-magnetic metals between the step of removing the magnetic material and the step of washing with water.

13. A method for producing a resin composition molded article according to any one of claims 1 to 12, wherein the crushed material is pulverized using a fine grinder.

14. A method for producing a resin composition molded product according to any one of claims 1 to 13, wherein the crushed material is pulverized under conditions that allow the resin composition powder to pass through a sieve with a mesh size of 3 mm.

15. A method for producing a resin composition molded article according to any one of claims 1 to 14, wherein the resin composition molded article is molded by extrusion molding the resin composition powder.

16. A method for producing a resin composition molded product according to any one of claims 1 to 15, comprising dehydrating the crushed material after the water-washing treatment using a compression reducer, and pulverizing the crushed material after the dehydration treatment.

17. A method for producing a resin composition molded product described in any one of claims 1 to 16, comprising adding and mixing at least one of a low melting point resin-containing powder and a non-low melting point resin-containing powder that have been prepared in advance to the resin composition powder to obtain a resin composition powder mixture, and molding the resin composition powder mixture.

18. A method for producing a resin composition molded body described in any one of claims 1 to 17, wherein the low-melting point resin-containing powder contains 60 mass% or more of a low-melting point resin.

19. A method for producing a resin composition molded product described in any one of claims 1 to 18, wherein the non-low melting point resin-containing powder contains 60 mass% or more of a non-low melting point resin.

20. A method for producing a resin composition molded body described in any one of claims 1 to 19, comprising adding and mixing a previously prepared cellulose-based material powder to the resin composition powder mixture to obtain a cellulose-based material-containing resin composition powder mixture, and molding the cellulose-based material-containing resin composition powder mixture.

21. A method for producing a resin composition molded product described in any one of claims 1 to 20, wherein the resulting resin composition molded product has a bending strength of 20 MPa or more, measured in accordance with Method B specified in JIS A 5741:2016.

22. A method for producing a resin composition molded product described in any one of claims 1 to 21, wherein the area of ​​the mycelium grown portion of the obtained resin composition molded product after two weeks, as measured by method A specified in Annex A of JIS Z 2911:2018, is less than 25% of the total area.

23. A method for producing a resin composition powder for producing a resin composition molded product, comprising: preparing plastic waste containing at least one of waste plastic residues derived from general waste, waste plastics derived from industrial waste, and waste plastics derived from marine plastic waste, the plastic waste containing a low-melting point resin having a melting point in the range of 80°C or higher but lower than 190°C, and a non-low-melting point resin containing at least one of a high-melting point resin and a thermosetting resin having a melting point of 190°C or higher; performing a process for removing magnetic substances and a water-washing process on the plastic waste or crushed material obtained by crushing the plastic waste; and pulverizing the plastic waste or the crushed material after the water-washing process to obtain a resin composition powder.

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