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

Abstract

The manufacturing method of the resin composition molded body of the present disclosure is a 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, which is 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 containing at least one of a high melting point resin having a melting point of 190°C or higher and a thermosetting resin are prepared. A plastic waste is prepared, and a magnetic substance removal treatment and a water washing treatment are performed on the plastic waste or a crushed product obtained by crushing the plastic waste. After the water washing treatment, the plastic waste or the crushed product is crushed to obtain a resin composition powder, and the resin composition powder is molded to obtain a resin composition molded body.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a resin composition molded body and a method for manufacturing a resin composition powder for manufacturing a resin composition molded body.

Background Art

[0002] A woody resin composition molded body in which a cellulose-based material powder such as wood powder is dispersed in a resin is also called a wood plastic, and while having a texture similar to wood, it has advantages such as being less likely to corrode, crack, splinter, and being lightweight compared to wood. For this reason, woody resin composition molded bodies are widely used as materials for building materials and the like. As the resin of the woody resin composition molded body, the use of a low melting point resin such as waste-derived polypropylene has been studied (see, for example, Patent Document 1, Patent Document 2, and Non-Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a resin raw material for a resin composition molded body, it is desirable to use plastic waste including waste plastic from the perspective of promoting resource circulation and significantly contributing to the reduction of CO2 emissions due to incineration of waste. However, conventionally, it has been common to separate and recover only low-melting-point resins that are easily thermoformed from plastic waste and use them. Since the separated and recovered low-melting-point resins can be thermoformed, they are used for material recycling as recycled resins. On the other hand, the waste plastic residue remaining after separating and recovering the low-melting-point resin has an increased content ratio of non-low-melting-point resins such as high-melting-point resins and thermosetting resins, making thermoforming difficult. For this reason, it is difficult to utilize the waste plastic residue other than thermal recycling. For this reason, the material recycling rate of plastic waste in Japan is low. In recent years, there has been an increasing demand to increase the material recycling rate of plastic waste. However, according to the study by the present inventor, waste plastic residues derived from general waste, waste plastic derived from industrial waste, and waste plastic derived from marine plastic waste have the problem that thermoforming becomes difficult due to the mixing of inorganic substances such as magnetic substances, oils and fats, food residues, and organic substances such as surfactants. Inorganic substances may damage the manufacturing equipment for manufacturing the resin composition molded body and hinder the continuous production of the resin composition molded body. Since organic substances serve as nutrients for microorganisms such as mold and bacteria and may promote the growth of microorganisms, it is important to reduce the amount of mixing. Since organic substances have a high affinity for waste plastic, a process is required to reduce the amount of organic substances adhering to waste plastic to such an extent that the growth of microorganisms can be suppressed.

[0006] An object of the present disclosure is to provide a method for manufacturing a resin composition molded body that can be effectively utilized even when plastic waste containing a low-melting-point resin and a non-low-melting-point resin is mixed with inorganic substances such as magnetic substances, oils and fats, food residues, and organic substances such as surfactants.

Means for Solving the Problems

[0007] The present disclosure relates to a method for manufacturing a resin composition molded body, which prepares a plastic waste including 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 including 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 including at least one of a high melting point resin having a melting point of 190°C or higher and a thermosetting resin, performs a magnetic substance removal treatment and a water washing treatment on the plastic waste or a crushed product obtained by crushing the plastic waste, crushes the plastic waste or the crushed product after the water washing treatment to obtain a resin composition powder, and molds the resin composition powder to obtain a resin composition molded body.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following embodiments, a wood resin composition molded body containing wood powder is taken as an example of the resin composition molded body, and its manufacturing method will be described.

[0010] FIG. 1 is a block diagram of a resin composition molded body manufacturing system that can be used in the method for manufacturing a resin composition molded body 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.

[0011] The resin composition powder supply unit 10 manufactures and stores the resin composition powder for manufacturing the resin composition molded body from plastic waste. The resin composition powder supply unit 10 has a crusher 11, a magnetic separator 12, a non-magnetic metal separator 13, a washer 14, a compression volume reducer 15, a pulverizer 16, a storage tank 17, and a metering tank 18 for plastic waste.

[0012] The plastic waste includes 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 which is a mixture of one or both of a high melting point resin having a melting point of 190°C or higher and a thermosetting resin. The plastic waste may contain substances other than synthetic resins. The substances other than synthetic resins may be inorganic substances or organic substances. The inorganic substances are, for example, inorganic substances such as magnetic substances, non-magnetic metals, glass, pebbles, metals, shells, sand, drying materials such as silica gel, and iron-based deoxidizers. Examples of magnetic substances include iron, cobalt, and nickel. An example of a non-magnetic metal is aluminum. Examples of organic substances are, for example, oils and fats, food residues, and surfactants.

[0013] 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 the high melting point resin 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). The thermosetting resin is the resin 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 the plastic waste may be of one kind or two or more kinds.

[0014] Plastic waste is any one or a mixture of two or more of the waste plastics including waste plastic residues derived from general waste, waste plastics derived from industrial waste, and waste plastics derived from marine plastic waste. Plastic means a molded product of synthetic resin. For example, plastic waste is waste containing 50% by mass or more of waste plastic. The waste plastic content of the plastic waste may be, for example, in the range of 50% by mass or more and 100% by mass or less, or in the range of 50% by mass or more and 99.5% by mass or less, or in the range of 50% by mass or more and 70% by mass or less.

[0015] The ignition residue of the plastic waste may be in the range of 0.5% by mass or more and 10% by mass or less. The ignition residue is, for example, a value measured by the following method. (Method for measuring ignition residue) Weigh the sample in a crucible before heating. Use a high-temperature electric furnace to hold at 600 °C for 2 hours to completely burn the organic components including synthetic resin. After cooling, divide the weight of the remaining sample by the weight before heating to obtain the ignition residue as a percentage.

[0016] General waste refers to other waste excluding industrial waste and marine plastic waste, and includes household waste discarded from ordinary households. Examples of waste plastics derived from general waste include plastics used as containers and packaging materials for products. Waste plastic residue is the residue after separating and recovering a part of the resin contained in waste plastics derived from general waste, for example, the residue after separating and recovering a part of low-melting-point resin. The low-melting-point resin to be separated and recovered includes, for example, at least any one of PP, PE, and PS, and may include PP and PE. The waste plastic residue may be the residue after separating and recovering 5% by mass or more, or 5% by mass or more and 95% by mass or less, or 5% by mass or more and 50% by mass or less, or 5% by mass or more and 15% by mass or less of the low-melting-point resin contained in the waste plastics. Note that the proportion of the sum of PP and PE in the separated and recovered low-melting-point resin may be 20% by mass or more, may be within the range of 50% by mass or more and 100% by mass or less, or may be within the range of 70% by mass or more and 100% by mass or less.

[0017] Waste plastics derived from industrial waste are waste plastics generated along with business activities. Examples of waste plastics derived from industrial waste include off-spec products and surplus products of products. Waste plastics derived from marine plastic waste are waste plastics accumulated in the ocean by directly discarding plastic products into the sea or by plastic products discarded on land flowing into the sea through rivers, lakes, etc. Plastic products are, for example, plastic pieces, PET bottles, fishing gear, etc. Waste plastics derived from marine plastic waste include, for example, microplastics in which plastic products have deteriorated due to the influence of waves and ultraviolet rays and become 5 mm or less.

[0018] The contents of the low melting point resin and the non-low melting point resin in the plastic waste synthetic resin are not particularly limited. The content of the low melting point resin may be, for example, in the range of 3% by mass or more and 95% by mass or less. The content of the non-low melting point resin may be, for example, in the range of 5% by mass or more and 97% by mass or less. The ratio of the content of the low melting point resin to the non-low melting point resin (low melting point resin / non-low melting point resin content ratio) may be, for example, in the range of 1 / 3 or more and 5.00 or less by mass ratio. The content of the low melting point resin may be 80% by mass or less, or may be 70% by mass or less. The content of the low melting point resin may be in any of the ranges of 5% by mass or more and 80% by mass or less, 25% by mass or more and 80% by mass or less, 25% by mass or more and 75% by mass or less, 30% by mass or more and 70% by mass or less. The content of the non-low melting point resin may be 20% by mass or more, or may be 30% by mass or more. The content of the low melting point resin may be in any of the ranges of 20% by mass or more and 95% by mass or less, 20% by mass or more and 75% by mass or less, 25% by mass or more and 75% by mass or less, 30% by mass or more and 70% by mass or less. The low melting point resin / non-low melting point resin content ratio may be less than 4.00 by mass ratio, or may be in the range of 1 / 3 or more and 3.00 or less.

[0019] 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, and may be, for example, within the range of 25% by mass or more and 95% by mass or less, or may be within the range of 35% by mass or more and 90% by mass or less. The total content of PE, PP and PS in the synthetic resin contained in the waste plastic residue may be 80% by mass or less, or may be 70% by mass or less. The total content of PE, PP and PS may be within any of the ranges of 5% by mass or more and 80% by mass or less, 25% by mass or more and 80% by mass or less, 25% by mass or more and 75% by mass or less, 30% by mass or more and 70% by mass or less. The total content of PE and PP with respect to the total amount of the low melting point resin may be 90% by mass or less, and may be within the range of 20% by mass or more and 80% by mass or less. The content of the non-low melting point resin in the synthetic resin may be, for example, 5% by mass or more, and may be within the range of 5% by mass or more and 75% by mass or less, or may be within the range of 10% by mass or more and 65% by mass or less. The ratio of the content of the low melting point resin to the non-low melting point resin in the synthetic resin (low melting point resin / non-low melting point resin content ratio) may be, for example, within the range of 1 / 3 or more and 5.00 or less by mass ratio, or may be within the range of 0.71 or more and 3.00 or less. The low melting point resin / non-low melting point resin content ratio may be less than 4.00 by mass ratio, or may be within the range of 1 / 3 or more and 3.00 or less. 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, within the range of 0.01 or more and 100 or less by mass ratio, or may be within the range of 0.05 or more and 50 or less. The content of the thermosetting resin in the synthetic resin may be, for example, 0% by mass or more, and may be within the range of 1% by mass or more and 10% by mass or less. The content of the high melting point resin in the synthetic resin may be, for example, 5% by mass or more, and may be within the range of 10% by mass or more and 90% by mass or less.

[0020] The form of the plastic waste is not particularly limited and may be, for example, in the form of a film or a lump. When the production unit (lot) of the resin composition molded body is divided according to the type of plastic waste, the plastic waste used in each production unit may have different places of generation and times of generation. The plastic waste used in each production unit may have, for example, a standard deviation of the content of the low melting point resin of 2% by mass or more, and may be within the range of 2% by mass or more and 23% by mass or less.

[0021] The crusher 11 is a device that crushes plastic waste to obtain plastic pieces. As the crusher 11, for example, a single-screw crusher can be used. The size of the plastic pieces obtained by the crusher 11 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.

[0022] The magnetic separator 12 is a device that removes and recovers magnetic substances contained in the plastic pieces. As the magnetic separator 12, for example, a suspended magnetic separator, a pulley magnetic separator, a drum magnetic separator, or a roll magnetic separator can be used. Examples of magnetic substances include iron, stainless steel, and ferrite. The magnetic separator 12 may be used alone or in combination of two or more kinds.

[0023] The non-magnetic metal separator 13 is a device that removes and recovers non-magnetic metals contained in the plastic pieces. Examples of non-magnetic metals include aluminum, copper, zinc, and brass. As the non-magnetic metal separator 13, an eddy current separator can be used.

[0024] The cleaning machine 14 is a device for cleaning and removing deposits such as detergents, food stains, and oil stains adhering to plastic pieces. As the cleaning machine 14, a wet grinding and cleaning machine equipped with a grinding function can be used. The wet grinding and cleaning machine may grind plastic pieces in water. As the grinding function of the plastic pieces, a grinding machine equipped with a fixed blade and a rotating blade and sandwiching the plastic pieces between the fixed blade and the rotating blade for grinding can be used. By using the wet grinding and cleaning machine to grind the plastic pieces into plastic coarse particles and cleaning them, the deposits adhering to the plastic coarse particles can be removed more efficiently.

[0025] The squeezing and volume reducing machine 15 is a device for squeezing plastic coarse particles to remove the moisture adhering to the plastic coarse particles and reducing the volume to obtain plastic coarse powder. As the squeezing and volume reducing machine 15, a screw type squeezing and volume reducing machine equipped with a screw in a barrel having drain holes can be used. By using the screw type squeezing and volume reducing machine, due to the frictional heat between the screw, the barrel, and the plastic coarse particles, the moisture is removed, and a part of the low melting point resin of the plastic coarse particles melts, and the plastic coarse particles are fused together, thereby reducing the volume of the plastic coarse particles.

[0026] The grinding machine 16 is a device for grinding plastic coarse powder to produce fine resin composition powder. As the grinding machine 16, a fine grinding machine (cutter mill), a hammer mill, or a pin mill can be used. The fine grinding machine (cutter mill) is a device equipped with a fixed blade and a rotating blade and sandwiching plastic pieces between the fixed blade and the rotating blade for grinding. The grinding machine 16 may be used alone or in combination of two or more types.

[0027] The resin composition powder outlet of the crusher 16 may have a sieve arranged. The crusher 16 may be configured to, for example, retain plastic coarse powder of a coarse size inside the crusher 16 and take out only the fine resin composition powder passing 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 mesh size of the sieve may be 3 mm, 2 mm, or 1 mm. If the mesh size of the sieve is, for example, 500 μm or less, there is a risk that the crushed low-melting resin will melt due to the heat generated by the crushing of the plastic coarse powder, and the melted resin will solidify on the surface of the sieve, easily causing the sieve to become clogged.

[0028] The storage tank 17 is a tank for temporarily storing the resin composition powder produced by the crusher 16. The weighing tank 18 is a tank for weighing the resin composition powder sent from the storage tank 17 and temporarily storing a predetermined amount of the resin composition powder.

[0029] The resin composition powder supply unit 10 can produce the resin composition powder from plastic waste, for example, as follows. FIG. 2 is a flowchart of a method for producing a resin composition powder for manufacturing a resin composition molded body according to an embodiment of the present disclosure.

[0030] The method for producing the resin composition powder of the present embodiment includes a crushing step S11, a magnetic substance removal treatment step S12, a non-magnetic metal removal treatment step S13, a water washing treatment step S14, a volume reduction treatment step S15, and a pulverization step S16.

[0031] The crushing step S11 is a step of crushing plastic waste to obtain plastic pieces. The crushing step S11 is performed using the crusher 11.

[0032] The magnetic substance removal process step S12 is a step of removing and recovering the magnetic substances contained in the plastic pieces. The magnetic substance removal process step S12 is carried out using a magnetic separator 12. By performing the magnetic substance removal process step S12, the magnetic substances mixed in the plastic pieces can be surely removed. By removing the magnetic substances, in the pulverization process step S16, it is possible to prevent the adverse effect that the magnetic substances stay inside the pulverizer and wear and damage the blades inside the pulverizer, thereby gradually reducing the pulverization efficiency of the pulverizer. In particular, after the plastic waste is made into plastic pieces by the crushing process step S11, by performing the magnetic substance removal process step S12, molded bodies such as push pumps used in containers for hand soap and shampoo are crushed, so that metal magnetic substances such as spring materials and screw materials used inside the molded bodies can be more surely removed.

[0033] The non-magnetic metal removal process step S13 is a step of removing and recovering the non-magnetic metals contained in the plastic pieces. The non-magnetic metal removal process step S13 is carried out using a non-magnetic metal separator 13.

[0034] The water washing process step S14 is a step of washing and removing the deposits (especially organic substances) adhering to the plastic pieces by washing them with water. In the water washing process step S14, while pulverizing the plastic pieces into plastic coarse particles, the deposits adhering to the plastic coarse particles may be washed and removed. The water washing process step S14 is carried out using a washing machine 14. By performing the water washing process step S14, in the pulverization process step S16, it is possible to prevent the adverse effects that organic substances such as detergents, food stains, and oil stains melt and adhere to the blades inside the pulverizer in the pulverization process step S16, resulting in a decrease in pulverization efficiency, or that organic substances melt and adhere to the sieve of the pulverizer, blocking the sieve. Also, since the amount of organic substances mixed in the obtained resin composition powder is reduced, it becomes difficult for microorganisms to multiply.

[0035] The volume reduction process step S15 is a step of removing the moisture adhering to the plastic coarse particles and reducing the volume to obtain plastic coarse powder. The volume reduction process step S15 is carried out using a squeezing volume reduction machine 15.

[0036] The pulverization step S16 is a step of pulverizing the plastic coarse powder to obtain the resin composition powder. In the method for manufacturing the resin composition powder of the present 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 separation. The pulverization step S16 is performed using the pulverizer 16. The resin composition powder obtained by pulverization is sent to the storage tank 17.

[0037] When the plastic waste is in the form of a bale or a lump, it may be crushed using a crusher before the crushing step S11. In addition, various large magnetic wastes such as batteries, lighters, spray cans, razors, and injection needles may be mixed in the plastic waste. Therefore, before the crushing step S11, the large magnetic waste may be removed and recovered using a magnetic separator.

[0038] The wood powder supply unit 20 manufactures and stores the wood powder used as a raw material for the resin composition molded body from waste wood. The wood powder supply unit 20 includes a crusher 21, a magnetic separator 22, a pulverizer 23, a storage tank 24, and a metering tank 25.

[0039] As the waste wood, for example, construction waste wood, thinned wood, and sawdust can be used.

[0040] The crusher 21 is a device that crushes waste wood to obtain wood pieces. As the crusher 21, for example, a single-shaft pulverizer can be used. The size of the wood pieces obtained by the crusher 21 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.

[0041] The magnetic separator 22 is a device for removing and recovering magnetic substances contained in wood chips. As the magnetic separator 22, for example, a suspension 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 substances include nails and bolts. The magnetic separator 12 may be used alone or in combination of two or more types.

[0042] The crusher 23 is a device for crushing wood chips to produce fine wood powder. As the crusher 23, a fine crusher (cutter mill), a hammer mill, or a pin mill can be used. The crusher 23 may be used alone or in combination of two or more types.

[0043] A sieve may be arranged at the wood powder outlet of the crusher 23. The crusher 16 may be configured to, for example, retain coarse-sized plastic coarse powder inside the crusher 16 and take out only the fine resin composition powder passing 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 mesh size of the sieve may be 2 mm, 1 mm, or 500 μm.

[0044] The particle size of the wood powder is not particularly limited. However, in particles with a major axis of 1.0 mm or more, the content of particles with a major axis of 3.0 mm or more may be 35% by number or less, or 20% by number or less. Also, the content of particles with a major axis of less than 2.0 mm may be 30% by number or more, or 50% by number or less. The content of these particles can be determined by observing the cross-section of the resin composition molded body using an optical microscope and measuring the particle diameter of the wood powder.

[0045] The storage tank 24 is a tank for temporarily storing the wood powder produced by the crusher 23. The weighing tank 25 is a tank for weighing the wood powder sent from the storage tank 24 and temporarily storing a predetermined amount of wood powder.

[0046] The low melting point resin powder supply unit 30 stores the low melting point resin powder used as a raw material for the resin composition molded body as needed. The low melting point resin powder supply unit 30 includes a storage tank 31 and a weighing tank 32.

[0047] The low melting point resin powder contains a low melting point resin. The low melting point resin is, for example, PS, ABS, PE, PMMA, PC, PP, PA12, or POM. The low melting point resin may be used alone or in combination of two or more. The low melting point resin powder may contain a non-low melting point resin. The content of the low melting point resin in 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 pulverizing plastic waste containing 60% by mass or more of the low melting point resin. The low melting point resin powder may pass through a sieve with a mesh size of 3 mm. As the low melting point resin powder, for example, waste such as shrink films (PE), binding bands (PP), and expanded polystyrene (PS) after being used for product packaging, bundling, and curing can be pulverized to 3 mm or less and used. Also, recycled plastics (PP, PE, PS) recovered and manufactured based on the Container Packaging Recycling Law and pulverized to 3 mm or less can be used.

[0048] The storage tank 31 is a tank that temporarily stores the low melting point resin powder. The weighing tank 32 is a tank that weighs the low melting point resin powder sent from the storage tank 31 and temporarily stores a predetermined amount of the low melting point resin powder.

[0049] 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 body as needed. The non-low melting point resin powder supply unit 40 includes a storage tank 41 and a weighing tank 42.

[0050] The non-low melting point resin powder contains a non-low melting point resin. The non-low melting point resin is, for example, PET, PA6, PBT, PPS, PEEK, PI, PU, or 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 pulverizing plastic waste containing 60% by mass or more of the non-low melting point resin. The non-low melting point resin powder may pass through a sieve with an opening of 3 mm. As the non-low melting point resin powder, recycled raw materials such as pulverized waste PET used as a container for selling eggs or a food packaging material to 3 mm or less can be used.

[0051] The storage tank 41 is a tank for temporarily storing the non-low melting point resin powder. The metering tank 42 is a tank that measures the non-low melting point resin powder sent from the storage tank 41 and temporarily stores a predetermined amount of the non-low melting point resin powder.

[0052] The additive supply unit 50 stores additives that are optionally added to the resin composition molded body. The additive supply unit 50 includes a storage tank 51 and a metering tank 52.

[0053] As additives, for example, various additives applied to conventional resin composition molded articles such as pigments, compatibilizers for improving the affinity between the resin and wood powder, fillers, lubricants, weathering agents, heat stabilizers, foaming agents, antistatic agents, etc. can be used. Pigments are used to color the resin composition molded article. As pigments, inorganic pigments, organic pigments, and mixtures thereof can be used. Compatibilizers are used to increase the adhesion between the wood powder and the resin component and improve the strength physical properties and water resistance of the resin composition molded article. As compatibilizers, maleic anhydride-modified polypropylene-based compatibilizers can be used. Lubricants are added to improve the slipperiness with the mold. As lubricants, oxidized polyolefin wax, acid-modified polyolefin wax, calcium stearate, and zinc stearate can be used. As weather-resistant materials, ultraviolet absorbers (UVA), light absorbers (HALS), and antioxidants can be used.

[0054] The storage tank 51 is a tank for temporarily storing additives. The metering tank 52 is a tank that measures the additives sent from the storage tank 51 and temporarily stores a predetermined amount of additives. The storage tank 51 and the metering tank 52 may be provided one for each type of additive, or one may be provided for an additive mixture in which two or more types of additives are mixed.

[0055] The molded article manufacturing unit 60 manufactures a resin composition molded article. The molded article manufacturing unit 60 includes a mixer 61, a storage tank 62, and an extruder 63.

[0056] The mixer 61 is a device that mixes the resin composition powder that is the raw material of the resin composition molded article, at least one of the low-melting-point resin-containing powder and the non-low-melting-point resin-containing powder, wood powder, and additives to obtain a raw material mixture. As the mixer 61, for example, a heater mixer can be used. By using a heater mixer and mixing the above raw materials while heating, a mixture in which each raw material is uniformly dispersed can be obtained. The heating temperature of the heater mixer varies depending on the resin contained in the raw material mixture. For example, when the resin with the lowest melting point in the raw material mixture is PE, it may be in the range of 100 to 150°C.

[0057] The storage tank 62 is a tank that temporarily stores the raw material mixture. The storage tank 62 supplies a predetermined amount of the raw material mixture to the extruder 63.

[0058] The extruder 63 is a device that forms the raw material mixture into a predetermined shape. As the extruder 63, for example, a single-screw extruder or a twin-screw extruder can be used. 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. For example, when containing PE, it is 150°C or higher. On the other hand, since the wood powder decomposes and gasifies at 190°C or higher, which may cause bubbles in the resin composition molded body, the molding temperature is preferably less than 190°C.

[0059] Next, a method for manufacturing a resin composition molded body using the resin composition molded body manufacturing system 100 will be described. FIG. 3 is a flowchart of a method for manufacturing a resin composition molded body according to an embodiment of the present disclosure. The method for manufacturing a resin composition molded body of the present embodiment includes an analysis step S21, a mixing step S22, and a molding step S23.

[0060] The analysis step S21 is a step of analyzing the composition of the resin composition powder. As 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. 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.

[0061] For the analysis of the content of the low-melting-point resin and the non-low-melting-point resin in the resin composition powder, for example, a method of separating the two using the specific gravity difference between the low-melting-point resin and the non-low-melting-point resin and measuring the content of each separated resin can be used. In the present embodiment, the analysis was performed as follows. The resin composition powder is immersed in an aqueous sodium chloride solution as a sample powder. Next, the amount of the floating matter floating on the surface of the aqueous sodium chloride solution and the amount of the sediment that settles are measured. The floating matter is scooped up from the aqueous sodium chloride solution. The sediment is recovered by filtering the aqueous sodium chloride solution after scooping up the total amount of the floating matter. After washing the recovered floating matter and sediment with water, they are dried and the amounts of the floating matter and sediment are measured. Then, the amount of the floating matter is taken as the content of the low melting point resin, and the amount of the sediment is taken 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.

[0062] The mixing step S22 is a step of mixing the resin composition powder, at least one of the low melting point resin-containing powder and the non-low melting point resin-containing powder, wood powder, and an additive to obtain a raw material mixture. The mixing step S22 is performed by mixing each raw material sent from the metering tanks 18, 25, 32, 42, 52 using the mixer 61. The obtained raw material mixture is sent to the storage tank 62.

[0063] In the mixing step S22, based on 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 obtained in the analysis step S21, the mixing ratio of the resin composition powder, the melting point resin-containing powder and / or the non-low melting point resin-containing powder is adjusted. 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, within the range of 50 to 90% by mass. The content of the wood powder may be, for example, within the range of 5 to 40% by mass. The content of the additive may be, for example, within the range of 5 to 40% by mass. The ratio of the content of the wood powder to the content of the low melting point resin (wood powder / low melting point resin content ratio) may be 5.0 or less. Also, 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 mixture may be within the range of 1 / 3 to 5 by mass ratio, or may be within the range of 1 / 3 to 1.40.

[0064] The shaping step S23 is a step of shaping the raw material mixture obtained in the mixing step S22 to obtain a shaped body of the woody resin composition. The shaping 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, and a shaped body of the woody resin composition in which the non-low melting point resin and the wood powder are dispersed in the low melting point resin can be obtained. The shape of the woody resin composition formed body is not particularly limited, and may be, for example, plate-shaped.

[0065] In the shaping step S23, the shaping temperature of the raw material mixture is preferably less than the melting point of the non-low melting point resin contained in the raw material mixture by 10°C. For example, when the melting point of the non-low melting point resin is 250°C, the shaping temperature is preferably less than 240°C. By leaving the non-low melting point resin in an unmelted state without melting it in the woody resin composition formed body, the non-low melting point resin is dispersed in an island shape in the formed 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 non-low melting point resin being dispersed in an island shape can reinforce the low melting point resin that is sea-like and has a low elastic modulus. Therefore, the entire resin composition formed body has high elasticity and high strength. Also, in the formulation system with added wood powder, there is a possibility that the wood powder will carbonize when the shaping temperature becomes 200°C or higher, so it is desirable to perform the shaping at 190°C or lower. The shaping temperature of the raw material mixture is preferably at a temperature equal to or higher than the melting point of the low melting point resin plus 5 to 10°C. The shaping temperature of the raw material mixture may be, for example, within the range of 160°C or higher and 190°C or lower. Note that the melting point of the non-low melting point resin means the lowest temperature among the melting points of the plurality of types of non-low melting point resins contained in the raw material mixture. The melting point of the low melting point resin indicates the highest temperature among the melting points of the plurality of types of low melting point resins contained in the raw material mixture.

[0066] From the viewpoint of improving the elasticity and strength of the resin composition formed body, the resin composition powder is preferably fine, and more preferably passes through a sieve with an opening of 1 mm.

[0067] The formed product of the woody resin composition obtained as described above contains wood powder and has a texture similar to wood, so it can be used as a wood substitute. The formed product of the resin composition can be used, for example, as civil engineering materials, building materials, and gardening materials. Examples of civil engineering materials include paving materials. Examples of building materials include floor materials, especially bathroom floor materials, roofing materials, wall materials, handrails, sashes, wood decks, fences, and the like. Examples of gardening materials include flower beds.

[0068] In the manufacturing method of the resin composition molded body of the present embodiment configured as described above, plastic waste containing a low melting point resin and a non-low melting point resin is crushed in the crushing step S11 to obtain a crushed product. After performing a magnetic substance removal treatment step S12, a non-magnetic metal removal treatment step S13, and a water washing treatment step S14 on the obtained crushed product, the pulverization step S16 is performed. Therefore, it is possible to efficiently remove inorganic substances, oils and fats, food residues, and organic substances such as surfactants mixed in the plastic waste. For this reason, according to the manufacturing method of the resin composition molded body of the present embodiment, the resin composition molded body can be industrially stably manufactured using plastic waste containing a low melting point resin and a non-low melting point resin.

[0069] In the manufacturing method of the resin composition molded body of the present embodiment, by using a fine pulverizer (cutter mill) as the pulverizer 16 in the pulverization step S16, the resin composition powder derived from plastic waste can be manufactured more advantageously industrially. Further, in the manufacturing method of the resin composition molded body of the present embodiment, when the resin composition powder derived from plastic waste passes through a sieve with an opening of 3 mm, since the non-low melting point resin is fine, the non-low melting point resin can be coated with the melt of the low melting point resin during the manufacture of the resin composition molded body. For this reason, the water resistance of the obtained resin composition molded body is further improved. Furthermore, in the manufacturing method of the resin composition molded body of the present embodiment, after the water washing treatment step S14, in the volume reduction treatment step S15, by using a squeezing volume reduction machine 15 to remove moisture and fuse plastic coarse particles together to reduce the volume, the pulverization efficiency in the pulverization step S16 is improved.

[0070] In the method for manufacturing a resin composition molded body according to this embodiment, when using waste plastic residues derived from general waste as plastic waste, the composition of the resin in the waste plastic residues is likely to vary. Therefore, when using resin composition powder derived from waste plastic residues, at least one of the previously prepared low melting point resin-containing powder and non-low melting point resin-containing powder may be added and mixed to obtain a resin composition powder mixture, and the resin composition powder mixture may be molded. By doing so, the contents of the low melting point resin and non-low melting point resin in the resin composition powder mixture can be adjusted, so that it becomes possible to stably manufacture a resin composition molded body.

[0071] In the method for manufacturing a resin composition molded body according to 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, since the content of the low melting point resin in the low melting point resin-containing powder is large, it becomes easier to adjust the addition amount of the low melting point resin-containing powder when the resin composition powder contains less low melting point resin. Further, in the method for manufacturing a resin composition molded body according to 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, since the content of the non-low melting point resin in the non-low melting point resin-containing powder is large, it becomes easier to adjust the addition amount of the non-low melting point resin-containing powder when the resin composition powder contains less non-low melting point resin.

[0072] In the method for manufacturing a resin composition molded body according to this embodiment, by adding wood powder to the resin composition powder derived from plastic waste and mixing it to obtain a wood powder-containing resin composition powder mixture, and molding the wood powder-containing resin composition powder mixture, a resin composition molded body having a texture similar to wood can be obtained. Instead of wood powder, cellulose-based material powders such as pulp powder can be used. Note that the particle size of the wood powder is correlated with the water resistance of the resulting resin composition molded body, and the finer the particle size of the wood powder, the more likely the water resistance of the resin composition molded body is to improve. From the viewpoint of improving the water resistance of the resin composition molded body, it is preferable that the wood powder passes through a sieve having an opening of 300 μm to 3 mm, and more preferably, it passes through a sieve having an opening of 500 μm.

[0073] In the method for producing a resin composition powder for producing a resin composition molded body according to this embodiment, plastic waste is crushed in the crushing step S11 to obtain crushed matter, and for the obtained crushed matter, a magnetic substance removal treatment step S12, a non-magnetic metal removal treatment step S13, and a water washing treatment step S14 are performed, and then it is pulverized. Therefore, it is possible to efficiently remove inorganic substances, fats and oils, food residues, and organic substances such as surfactants mixed in the plastic waste. For this reason, according to the method for producing a resin composition powder of this embodiment, it is possible to industrially and stably produce a resin composition powder that can be used for producing a resin composition molded body using waste plastic residues derived from general waste or waste plastic derived from industrial waste.

[0074] As described above, the embodiments of the present disclosure have been described, but the present disclosure is not limited thereto. For example, in this embodiment, plastic waste is crushed in the crushing step S11, but depending on the shape of the plastic waste, the crushing step S11 may be omitted. In this embodiment, non-magnetic metal contained in the plastic pieces is removed and recovered in the non-magnetic metal removal treatment step S13. However, for example, when the amount of non-magnetic metal contained in the plastic pieces is small, the non-magnetic metal removal treatment step S13 may be omitted. In the method for producing a resin composition powder of this embodiment, the plastic coarse particles after being washed in the water washing treatment step S14 are volume-reduced in the volume reduction treatment step S15, but they may be pulverized in the pulverization step S16 without being volume-reduced.

[0075] In this embodiment, the contents of the low-melting-point resin and the non-low-melting-point resin in the resin composition powder derived from plastic waste are measured in the analysis step S21, but the analysis step S21 is not an essential configuration. For example, when the contents of the low-melting-point resin and the non-low-melting-point resin in the plastic waste are known, the analysis step S21 may be omitted. Further, in this embodiment, the contents of the low-melting-point resin and the non-low-melting-point resin in the resin composition powder are measured in the analysis step S21. However, only the low-melting-point resin may be measured, and the amount obtained by subtracting the content of the low-melting-point resin from the resin composition powder may be used as the content of the non-low-melting-point resin. Alternatively, only 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 resin composition powder may be used as the content of the low-melting-point resin. Furthermore, in this embodiment, in the analysis step S21, the contents of the low-melting-point resin and the non-low-melting-point resin in the resin composition powder are measured using the difference in specific gravity, but the measurement method is not limited to this. For example, DSC (Differential Scanning Calorimeter), GC-MS (Gas Chromatography-Mass Spectrometer), infrared absorption spectroscopy, or elemental analysis (CHN coder) may be used. When using DSC, 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 resin composition powder may be used as the content of the low-melting-point resin.

[0076] In this embodiment, the molding step S23 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 may be any method that melts the low-melting-point resin in the resin composition powder to form a molten resin composition. For example, injection molding, press molding, casting molding, or laminated molding using a 3D printer can be used as the molding method of the resin composition molded body.

[0077] In this embodiment, the plastic coarse powder is pulverized by the pulverizer 16, and the wood chips are pulverized by the pulverizer 23. However, the plastic coarse powder and the wood chips may be simultaneously pulverized using the same pulverizer to produce a powder mixture containing the resin composition powder and the wood powder. Although the woody resin composition formed body containing wood powder has been described as an example of the resin composition formed body, it may not contain wood powder, and any resin composition powder derived from plastic waste may be used. Further, in this embodiment, waste wood is used as the raw material for the wood powder, but the raw material for the wood powder is not limited to waste wood.

Examples

[0078] Hereinafter, the present disclosure will be described in more detail based on examples. The present disclosure is not limited by these examples. In this example, as plastic waste, waste materials 1 to 4, general waste, and recycled resin in which the contents of the low melting point resin and the non-low melting point resin are the amounts shown in Table 1 below were used. Waste materials 1 to 4 are waste plastic residues derived from general waste remaining after separating and recovering the low melting point resin from general waste. Waste materials 1 to 4 have a lower ratio of low melting point resin content / non-low melting point resin content compared to general waste. For this reason, material recycling becomes difficult. In particular, those with a low melting point resin content / non-low melting point resin content ratio of less than 1.00 are difficult to recycle. The recycled resin is a low melting point resin separated and recovered from general waste. The recycled resin has a high ratio of low melting point resin content / non-low melting point resin content and is used for material recycling.

[0079]

Table 1

[0080] [Example 1] (Production of Resin Composition Powder) Waste 1 was put into a crusher and crushed. The obtained crushed material 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 substances. Next, the crushed material from which the iron-containing substances had been removed was crushed in a single-shaft coarse crusher until it passed through a sieve with an opening of 50 mm to obtain plastic pieces (crushing process). The magnetic substances contained in the obtained plastic pieces were removed and recovered using a suspension type magnetic separator and a pulley type magnetic separator (magnetic substance removal treatment process). Next, the non-magnetic metals contained in the plastic pieces were removed and recovered using a non-magnetic metal separator (non-magnetic metal removal treatment process). Next, the deposits adhering to the plastic pieces were pulverized and washed using a wet pulverizing washer until they passed through a sieve with an opening of 12 mm to obtain plastic coarse particles (water washing treatment process). Next, the plastic coarse particles obtained by the wet pulverizing washer were squeezed and dehydrated using a volume reduction press dehydrator to reduce the volume and obtain plastic coarse powder with a moisture content of 0.5% by mass (volume reduction treatment process). And finally, the plastic coarse powder was pulverized using a cutter mill type crusher until it passed through a sieve with an opening of 2 mm (pulverizing process). Thus, a resin composition powder was obtained. The presence or absence of the magnetic substance removal treatment process, the non-magnetic metal removal treatment process, the water washing treatment process, the volume reduction treatment process, and the opening diameter of the sieve used in the pulverizing process are shown in Table 2 below.

[0081] In the pulverizing process, the processing capacity long-term stability of the cutter mill type crusher was evaluated by the following method. The results are shown in Table 2 below.

[0082] (Processing capacity long-term stability) The pulverization process is carried out continuously for 12 hours, and the degree of reduction in pulverization capacity is evaluated. The feeding of the raw material into the cutter mill type pulverizer is adjusted so that the main shaft motor current value of the pulverizer becomes constant. The weight of the resin composition powder obtained during the 30 minutes from 30 minutes after the start of operation to 1 hour after the start of operation is taken as the initial processing amount. The weight of the resin composition powder obtained during the 30 minutes from 11 hours and 30 minutes after the start of operation to 12 hours after the start of operation is measured, converted into a percentage with respect to the initial processing amount, and the obtained value is taken as the processing capacity maintenance rate. When the processing capacity maintenance rate is 90% or more, it is designated as "A", when it is 70% or more and less than 90%, it is designated as "B", and when it is less than 70%, it is designated as "C". Note that the blades of the cutter mill type pulverizer are reground for each example and each comparative example and used for evaluation.

[0083] (Manufacture of Wood Flour) Waste wood was put into a crusher and crushed in a single-shaft coarse pulverizer until it passed through a sieve with an opening of 50 mm to obtain wood chips (crushing step). The magnetic substances contained in the obtained wood chips were removed and recovered using a suspension type magnetic separator and a pulley type magnetic separator (magnetic substance removal treatment step). Next, the wood chips were pulverized using a cutter mill type pulverizer until they passed through a sieve with an opening of 1 mm (pulverization step). Thus, wood powder was obtained. The opening diameter of the sieve used in the pulverization step is shown in Table 2 below.

[0084] (Manufacturing Method of Resin Composition Molding) 60 parts by mass of resin composition powder, 30 parts by mass of wood powder, and 10 parts by mass of an additive (a mixture containing a pigment, a compatibilizer, an inorganic filler, a lubricant, and a weather-resistant material) were mixed at 150 °C using a heat mixer. The obtained mixture was molded using an extruder having a mold with a rectangular cross-section shape of 30 mm in thickness and 300 mm in width to obtain a plate-shaped resin composition molding. The composition of the obtained resin composition molding is shown in Table 3 below.

[0085] The obtained resin composition molding was evaluated for flexural strength, water resistance, and mold resistance by the following methods. The results are shown in Table 3 below.

[0086] (Flexural Strength) In accordance with Method B specified in JIS A 5741:2016 (Wood-Plastic Composite Materials), the flexural strength (three-point bending) of full-scale test specimens is measured. The flexural strength of 20 MPa or more is designated as "S", 15 MPa or more and less than 20 MPa as "A", 10 MPa or more and less than 15 MPa as "B", and less than 10 MPa as "C".

[0087] (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 rate of change in thickness with respect to the thickness of the sample on the previous day is calculated from the following formula (1). Rate of change in sample thickness (%) = (Sample thickness - Sample thickness on the previous day) / Sample thickness on the previous day × 100 (1)

[0088] When the rate of change in sample thickness is 0.5% or less, assuming that the swelling rate of the sample thickness due to water absorption has reached equilibrium, the equilibrium swelling rate of the sample thickness is calculated using the following formula (2). The sample thickness is the average of the thicknesses at a total of five locations: the central part of the plane and the vicinity of each of the four corners. Equilibrium swelling rate (%) = {(Tf - Ti) / Ti} × 100 (2) In formula (2), Tf (unit: mm) is the thickness of the resin composition molded body when the rate of change in thickness is 0.5% or less, and Ti (unit: mm) is the thickness of the resin composition molded body before immersion in warm water. For water resistance, the case where the equilibrium swelling rate is 5% or less is designated as "S", 10% or less as "A", more than 10% and 20% or less as "B", and more than 20% as "C".

[0089] (Mildew resistance) In accordance with Method A specified in Appendix A (Testing of Plastic Products) of JIS Z 2911:2018 (Mildew Resistance Test Method), the area of the mycelium growth part of the sample after two weeks is measured. For mildew resistance, the case where the growth area is less than 25% is designated as "A", 25% or more and less than 50% as "B", and 50% or more as "C".

[0090] [Examples 2 to 16, Comparative Examples 1 to 3] Resin composition powders and wood powders were produced in the same manner as in Example 1, except that the conditions for producing the resin composition powders and the wood powders were changed as shown in Table 2. Resin composition molded articles were produced using the obtained resin composition powders and wood powders. Table 2 shows the long-term stability of the processing capacity of the pulverizer during the production of the resin composition powders, and Table 3 shows the flexural strength, water resistance, and mold resistance of the obtained resin composition molded articles.

[0091] [Comparative Example 4 and Reference Example 1] Instead of Waste 1, the plastic waste described in Table 2 was used. Instead of performing a water washing treatment step and a volume reduction treatment step on the plastic pieces after the non-magnetic metal removal treatment step, the plastic pieces were granulated, and the obtained granules were sprinkled with water and cooled (granulation - water sprinkling step). Resin composition powders and wood powders were produced in the same manner as in Example 1, except that the obtained granules were pulverized using a cutter mill type pulverizer until they passed through a sieve with a mesh size of 2 mm (pulverization step). Resin composition molded articles were produced using the obtained resin composition powders and wood powders.

[0092] [Reference Example 2] Instead of Waste 1, recycled resin was used. Resin composition powders and wood powders were produced in the same manner as in Example 1, except that the steps from the magnetic substance removal treatment step to the volume reduction treatment step were not performed, and the obtained product was pulverized using a cutter mill type pulverizer until it passed through a sieve with a mesh size of 2 mm (pulverization step). Resin composition molded articles were produced using the obtained resin composition powders and wood powders.

[0093]

Table 2

[0094]

Table 3

[0095] From the results shown in Tables 2 and 3, by using the resin composition powders obtained in Examples 1 to 16 in which each of the steps of the magnetic substance removal treatment step, non-magnetic metal removal treatment step, water washing treatment step, and volume reduction treatment step was carried out, it can be seen that it is possible to obtain a resin composition molded body excellent in bending strength, water resistance, and mold resistance. In particular, the resin composition molded bodies obtained in Examples 2 and 11 in which the screen opening of the pulverizer used in the production of the resin composition powder was 1 mm and Examples 8 and 16 in which the screen opening was 500 μm had improved bending strength. This is because by using the resin composition powder that passed through a screen with an opening of 1 mm or 500 μm, fine non-low melting point resin was dispersed in the resin composition molded body in an island shape. From this result, from the viewpoint of the bending strength of the resin composition molded body, it can be seen that the resin composition powder is fine, that is, it is preferable to finely pulverize the resin composition powder. On the other hand, when the resin composition powder is finely pulverized, the processing ability and long-term stability of the pulverizer tend to decrease, and it can be seen that it is preferable to set the screen opening to 1 mm or more in the case of a cutter mill type pulverizer. In addition, the resin composition molded bodies obtained in Examples 4 and 12 in which the screen opening of the pulverizer used in the production of wood powder was 500 μm had improved water resistance. This is because, as wood powder which is a water absorption factor in the water resistance test, by using fine wood powder that passed through a screen with an opening of 500 μm, the wood powder can be efficiently mixed and dispersed in the low melting point resin, thereby suppressing the change in water absorption of the resin composition molded body. From the results of Examples 1 to 16, by carrying out each of the steps of the magnetic substance removal treatment step, non-magnetic metal removal treatment step, water washing treatment step, and volume reduction treatment step according to the present disclosure, it was confirmed that waste plastic residues that were conventionally used as thermal recycling can be used for material recycling.

[0096] In contrast, in Comparative Example 1 where the water washing treatment step and the volume reduction treatment step were not carried out, the long-term stability of the processing capacity of the crusher decreased. This is because organic substances such as detergents, food stains, and oil stains were not removed and mixed into the crusher, the organic substances melted and adhered to the blades inside the crusher, resulting in a decrease in the crushing efficiency, and the organic substances melted and adhered to the sieve of the crusher, blocking the sieve. In addition, the water resistance of the resin composition molded body obtained in Comparative Example 1 decreased. This is because organic substances were mixed into the resin composition molded body. In Comparative Example 2 where the magnetic substance removal treatment step and the non-magnetic metal removal treatment step were not carried out, the long-term stability of the processing capacity of the crusher decreased. This is because the magnetic substances and non-magnetic metals were not removed and mixed into the crusher, causing the blades in the crusher to wear. In Comparative Example 3 where the magnetic substance removal treatment step, the non-magnetic metal removal treatment step, the water washing treatment step, and the volume reduction treatment step were not carried out, the long-term stability of the processing capacity of the crusher decreased significantly. This is because organic substances, magnetic substances, and non-magnetic metals were not removed and mixed into the crusher. In Comparative Example 4 and Reference Example 1 where the granulation - water spraying step was carried out instead of the water washing treatment step and the volume reduction treatment step, the long-term stability of the processing capacity of the crusher decreased, and the obtained resin composition molded body had a reduced mold resistance. This is because in the granulation - water spraying step, the organic substances contained in the plastic waste could not be removed. On the other hand, in Reference Example 2 using recycled resin, a resin composition molded body excellent in flexural strength, water resistance, and mold resistance can be obtained without carrying out each step from the magnetic substance removal treatment step to the volume reduction treatment step.

[0097] Aspects of the present disclosure are appended below. (Appendix 1) Prepare 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 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 containing at least one of a high melting point resin having a melting point of 190°C or higher and a thermosetting resin. Perform a magnetic substance removal treatment and a water washing treatment on the plastic waste or the crushed material obtained by crushing the plastic waste. Crush the plastic waste or the crushed material after the water washing treatment to obtain a resin composition powder, and mold the resin composition powder to obtain a resin composition molded body. A method for manufacturing a resin composition molded body.

[0098] (Appendix 2) The method for manufacturing a resin composition molded body according to Appendix 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.

[0099] (Appendix 3) The method for manufacturing 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 the general waste and the waste plastic derived from the 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.

[0100] (Appendix 4) The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 3, wherein the content of the low melting point resin in the synthetic resin contained in the waste plastic residue derived from the general waste and the waste plastic derived from the marine plastic waste is in the range of 5% by mass or more and 80% by mass or less.

[0101] (Appendix 5) The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 4, wherein the waste plastic residue derived from the general waste is the residue after separating and recovering a part of the low melting point resin contained in the waste plastic contained in the general waste.

[0102] (Appendix 6) The method for manufacturing a resin composition molded body according to Appendix 5, wherein the waste plastic residue derived from the general waste is the residue 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.

[0103] (Appendix 7) The waste plastic residue derived from the general waste contains at least one of polyethylene and polypropylene, and the total content of the polyethylene and the polypropylene with respect to the total amount of the low melting point resin is 90% by mass or less. A method for manufacturing a resin composition molded body according to any one of Supplementary Notes 1 to 6.

[0104] (Supplementary Note 8) The content of the high melting point resin in the synthetic resin contained in the waste plastic residue derived from the general waste is in the range of 10% by mass or more and 90% by mass or less. A method for manufacturing a resin composition molded body according to any one of Supplementary Notes 1 to 7.

[0105] (Supplementary Note 9) The content of the thermosetting resin in the synthetic resin contained in the waste plastic residue derived from the general waste is in the range of 0% by mass or more and 20% by mass or less. A method for manufacturing a resin composition molded body according to any one of Supplementary Notes 1 to 8.

[0106] (Supplementary Note 10) The ratio of the content of the thermosetting resin to the high melting point resin in the waste plastic residue derived from the general waste is in the range of 0.01 to 100 by mass ratio. A method for manufacturing a resin composition molded body according to any one of Supplementary Notes 1 to 9.

[0107] (Supplementary Note 11) The ratio of the content of the low melting point resin to the non-low melting point resin (low melting point resin / non-low melting point resin content ratio) in the waste plastic residue derived from the general waste is less than 4.00 by mass ratio. A method for manufacturing a resin composition molded body according to any one of Supplementary Notes 1 to 10.

[0108] (Supplementary Note 12) The manufacturing unit of the resin composition molded body is divided according to the type of the plastic waste, and the standard deviation of the content of the low melting point resin of the plastic waste used in each manufacturing unit is 2% by mass or more. A method for manufacturing a resin composition molded body according to any one of Supplementary Notes 1 to 11.

[0109] (Supplementary Note 13) The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 12, wherein the removal treatment of the magnetic substance is performed on the crushed material obtained by crushing the plastic waste.

[0110] (Appendix 14) The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 13, wherein a non-magnetic metal removal treatment is performed between the magnetic substance removal treatment and the water washing treatment.

[0111] (Appendix 15) The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 14, wherein the crushing of the crushed material is performed using a fine crusher.

[0112] (Appendix 16) The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 15, wherein the crushing of the crushed material is performed under the condition that the resin composition powder passes through a sieve with an opening size of 3 mm.

[0113] (Appendix 17) The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 16, wherein, in the water washing treatment, while crushing the plastic waste into plastic coarse particles, the attachments adhering to the plastic coarse particles are washed and removed.

[0114] (Appendix 18) The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 17, wherein the resin composition molded body is molded by extrusion molding of the resin composition powder.

[0115] (Appendix 19) After the water washing treatment, the crushed material is dehydrated using a squeezing volume reduction machine, The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 18, wherein the crushed material after the dehydration treatment is crushed.

[0116] (Appendix 20) Adding at least one of a previously prepared low melting point resin-containing powder and a non-low melting point resin-containing powder to the resin composition powder, mixing them to obtain a resin composition powder mixture, and molding the resin composition powder mixture. The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 19.

[0117] (Appendix 21) The method for manufacturing a resin composition molded body according to Appendix 20, wherein the low melting point resin-containing powder contains 60% by mass or more of a low melting point resin.

[0118] (Appendix 22) The method for manufacturing a resin composition molded body according to Appendix 20, wherein the non-low melting point resin-containing powder contains 60% by mass or more of a non-low melting point resin.

[0119] (Appendix 23) Adding a previously prepared cellulose-based material powder to the resin composition powder, mixing them to obtain a cellulose-based material-containing resin composition powder mixture, and molding the cellulose-based material-containing resin composition powder mixture. The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 22.

[0120] (Appendix 24) The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 23, wherein the flexural strength measured in accordance with Method B specified in JIS A 5741:2016 of the obtained resin composition molded body is 20 MPa or more.

[0121] (Appendix 25) The method for manufacturing a resin composition molded body according to any one of Appendices 1 to 24, wherein the area of the developed part of the mycelium after two weeks measured by Method A specified in Annex A of JIS Z 2911:2018 of the obtained resin composition molded body is less than 25% of the total area.

[0122] (Appendix 26) A method for manufacturing a resin composition powder for a resin composition molded body, comprising preparing a 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 and less 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; performing a magnetic substance removal treatment and a water washing treatment on the plastic waste or a crushed product obtained by crushing the plastic waste; and crushing the plastic waste or the crushed product after the water washing treatment to obtain a resin composition powder.

Explanation of reference numerals

[0123] 10…Resin composition powder supply unit, 11…Crusher, 12…Magnetic separator, 13…Non-magnetic metal separator, 14…Washing machine, 15…Pressurized volume reduction machine, 16…Grinder, 17…Storage tank, 18…Measurement tank, 20…Wood powder supply unit, 21…Crusher, 22…Magnetic separator, 23…Grinder, 24…Storage tank, 25…Measurement tank, 30…Low melting point resin powder supply unit, 31…Storage tank, 32…Measurement tank, 40…Non-low melting point resin powder supply unit, 41…Storage tank, 42…Measurement tank, 50…Additive supply unit, 51…Storage tank, 52…Measurement tank, 60…Molded body manufacturing unit, 61…Mixer, 62…Storage tank, 63…Extruder, 100…Resin composition molded body manufacturing system

Claims

1. A 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, 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 containing at least one of a high melting point resin having a melting point of 190°C or higher and a thermosetting resin. Prepare a plastic waste in which the content of the non-low melting point resin in the synthetic resin is 5% by mass or more and 75% by mass or less. Perform a magnetic substance removal treatment and a water washing treatment on the plastic waste or the crushed material obtained by crushing the plastic waste. Crush the plastic waste or the crushed material after the water washing treatment to obtain a resin composition powder. A method for manufacturing a resin composition molded body, which comprises molding the resin composition powder to obtain a resin composition molded body.

2. A 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, 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 containing at least one of a high melting point resin having a melting point of 190°C or higher and a thermosetting resin. Prepare a plastic waste. Perform a magnetic substance removal treatment and a water washing treatment on the plastic waste or the crushed material obtained by crushing the plastic waste. Crush the plastic waste or the crushed material after the water washing treatment to obtain a resin composition powder. Add a cellulose-based material powder prepared in advance to the resin composition powder and mix them to obtain a cellulose-based material-containing resin composition powder mixture in which the content of the cellulose-based material powder is 5% by mass or more and 40% by mass or less. A method for manufacturing a resin composition molded body, which comprises molding the cellulose-based material-containing resin composition powder mixture to obtain a resin composition molded body.

3. The method for manufacturing a resin composition molded body according to Claim 1 or 2, wherein the content of the low melting point resin in the synthetic resin contained in the waste plastic residues derived from general waste and the waste plastics derived from marine plastic waste is in the range of 5% by mass or more and 80% by mass or less.

4. A method for producing a resin composition molded body described in claim 1 or 2, wherein the content of the non-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 in the range of 10 mass% or more and 65 mass% or less.

5. The method for producing a resin composition molded body according to claim 1 or 2, 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.

6. The method for producing a resin composition molded body according to claim 1 or 2, wherein a ratio of a content of the low melting point resin to the non-low melting point resin in the waste plastic residue derived from general waste is less than 4.00 in terms of mass ratio.

7. 3. The method for producing a resin composition molded body according to claim 1 or 2, 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 synthetic resin contained in the plastic waste used in each production unit is 2 mass% or more.

8. The method for producing a resin composition molded article according to claim 1 or 2, wherein the magnetic substance removal treatment is carried out on crushed material obtained by crushing the plastic waste.

9. 3. The method for producing a resin composition molded article according to claim 1, further comprising the steps of: pulverizing the plastic waste into coarse plastic particles in a water washing treatment; and washing and removing any deposits adhering to the coarse plastic particles.

10. The method for producing a resin composition molded article according to claim 1 or 2, further comprising the steps of: dehydrating the crushed material after the water-washing treatment using a compression reducer; and pulverizing the crushed material after the dehydration treatment.

11. The method for producing a resin composition molded product according to claim 1 or 2, wherein the obtained 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.

12. The method for producing a resin composition molded product according to claim 1 or 2, wherein the area of ​​the mycelium-grown portion of the resin composition molded product after 2 weeks, as measured by method A specified in Annex A of JIS Z 2911:2018, is less than 25% of the total area.

13. 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, 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 containing at least one of a high melting point resin having a melting point of 190°C or higher and a thermosetting resin, wherein the content of the non-low melting point resin in the synthetic resin is 5% by mass or more and 75% by mass or less, prepare plastic waste, Perform a magnetic substance removal treatment and a water washing treatment on the plastic waste or the crushed material obtained by crushing the plastic waste, A method for producing a resin composition powder for producing a resin composition molded body, wherein the plastic waste or the crushed material after the water washing treatment is pulverized to obtain a resin composition powder.

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