Recycled plastic materials and manufacturing method thereof

Abstract

To provide a manufacturing method for RP material for food packaging containers from used packaging containers.SOLUTION: This manufacturing method includes a detection step (S14) for detecting the content of PP resin material obtained from RP material for food packaging containers. This manufacturing method includes a comparison step (S15) that compares the detection result of the PP resin material content detected in the detection step with a mixing ratio for food packaging containers, in which PP resin material, PE resin material, and talc are mixed at a predetermined ratio. This manufacturing method includes an addition step (S15) that adds a predetermined amount of one or more of the deficient components among the PP resin material, PE resin material, and talc, based on the comparison result of the comparison step, so that the detected result of the PP resin material content matches the mixed ratio for food packaging containers.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a recycled plastic material (hereinafter also simply referred to as "RP material"), a method for producing the same, and a food packaging sheet or food packaging container produced using the RP material and the production method. [Background technology]

[0002] In the manufacture of products using plastic materials (hereinafter referred to simply as "P materials"), in addition to using so-called virgin plastic resin materials, the use of RP materials is desired. According to Non-Patent Document 1, packaging containers etc. account for 47.5% (3.9 million tons) of the total amount of waste plastic generated, and packaging containers etc. account for 77.1% (3.16 million tons) of general waste by category. As packaging containers etc. account for such a large amount of distribution of waste, there is a desire to reuse RP materials from packaging containers etc. However, RP materials vary in quality depending on the origin of the resin material. Furthermore, there is a considerable amount of unshipped RP material due to production and processing losses during the P material manufacturing stage. On the other hand, there is also a considerable amount of P material waste that has been used in the market (in the case of P material waste used in the market, foreign matter may be mixed in even after cleaning). Therefore, unlike virgin materials, which have a consistent material quality, RP materials tend to be contaminated with a variety of materials and foreign matter, resulting in a decline in material properties. Furthermore, material bias and variation are likely to occur, making it difficult to promote reuse. [Prior art documents] [Non-patent literature]

[0003] Publisher: Japan Industrial Publishing Co., Ltd. Published June 10, 2022 Japan Plastics Industry Federation Magazine Plastics June 2022 Issue Pages 79-83 Author: Masashi Hanba

[0004] Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, the use of RP materials has also been desired in the field of food packaging containers. However, containers for packaging food for the general public are subject to regulations such as the Food Sanitation Act, and product development of food packaging containers using RP materials is bound by different constraints than product development in other general fields (e.g., daily necessities, shipping pallets, containers, etc.). For example, in the case of food packaging containers, since they package ingredients for the general consumer, it is desirable to consider purchasing from a wide consumer base and keep manufacturing costs low. Furthermore, from the perspective of mass production, mass consumption, and mass disposal, it is desirable to avoid environmental impact despite mass production, and therefore limited RP resin materials are often used. Under these constraints, when manufacturing RP materials for food packaging containers removed from used packaging containers, it is necessary to meet the requirements (needs) of consumers, product providers, manufacturers, etc. who actually use the materials in terms of heat resistance, impact resistance, rigidity, etc. The present invention has been made to solve the above-mentioned problems. Its purpose is to provide an excellent RP material or a method for manufacturing an excellent RP material when manufacturing RP materials for food packaging containers by removing them from used packaging containers. Another object is to provide an excellent food packaging sheet or food packaging container using the RP material or the manufacturing method for the RP material. [Means for solving the problem]

[0006] In order to achieve the above objects, the present invention has the following means: That is, as Means 1, a method for producing an RP material for food packaging containers by removing used packaging containers and producing the RP material for food packaging containers, characterized by comprising: a detection step of detecting the content of polypropylene (hereinafter referred to as "PP") resin material obtained from the RP material for food packaging containers, a comparison step of comparing the detection result of the PP resin content detected in the detection step with a food packaging container mixing ratio in which the PP resin component, polyethylene (hereinafter referred to as "PE") resin component, and inorganic filler component are mixed in a predetermined ratio, and an addition step of adding a predetermined amount of one or more of the missing components from the PP resin component, the PE resin component, and the inorganic filler component based on the comparison result of the comparison step so that the detection result becomes the food packaging container mixing ratio.

[0007] As a second measure, in the first measure, the target mixing ratios of the PP resin component, the PE resin component, and the inorganic filler component in the mixing ratios for food packaging containers are preferably PP resin: 35-50%, PE resin: 5-35%, and inorganic filler: 30-55%. When the target mixing ratios of the PP resin component, the PE resin component, and the inorganic filler component are within the above ranges, the requirements (needs) of consumers who actually use the product, product providers, manufacturers, etc. can be met in terms of heat resistance, impact resistance, rigidity, etc.

[0008] As a third measure, in the first or second measures, it is desirable that the target density of the RP material after the addition step is completed, melt-kneaded, is 1 gram per cubic centimeter or more. When the target density is 1 gram per cubic centimeter or more, gravity separation becomes easier. The target density may be 1.1 grams per cubic centimeter or more or 1.05 grams per cubic centimeter or more. Means 4: A food packaging sheet or food packaging container manufactured using the RP material manufacturing method of any one of means 1 to 3.

[0009] As means 5, the RP material for food packaging containers removed from used packaging containers is characterized in that it comprises polypropylene resin material, polyethylene resin material and inorganic filler, which are obtained from the RP material for food packaging containers and whose content is detected, and a predetermined amount of one or more of the missing components is added so that the detection result becomes the mixing ratio for food packaging containers based on the comparison result of comparing the detection result of the PP resin material whose content is detected with the mixing ratio for food packaging containers in which the PP resin material, PE resin material and inorganic filler material are mixed in a predetermined ratio.

[0010] As a sixth aspect, in the fifth aspect, it is desirable that the target mixing ratios of the PP resin component, the PE resin component, and the inorganic filler component in the mixing ratios for food packaging containers are PP resin: 35-50%, PE resin: 5-35%, and inorganic filler: 30-55%. When the target mixing ratios of the PP resin component, the PE resin component, and the inorganic filler component are within the above ranges, when manufacturing RP materials for food packaging containers removed from used packaging containers, the requirements (needs) of consumers, product providers, manufacturers, etc. who actually use the materials can be met in terms of heat resistance, impact resistance, rigidity, etc.

[0011] As a seventh measure, it is desirable that in the fifth or sixth measure, the target density of the RP material after melt-kneading is 1 gram per cubic centimeter or more. The target density may be 1.1 grams per cubic centimeter or greater, or 1.05 grams per cubic centimeter or greater.

[0012] Means 8: A food packaging sheet or food packaging container produced using the RP material of any one of means 5 to 7. [Effects of the Invention]

[0013] According to the present invention, an excellent RP material or a method for producing an excellent RP material can be provided when producing an RP material for food packaging containers removed from used packaging containers. Furthermore, when the above-mentioned excellent RP material or the method for producing an excellent RP material is used, the food packaging sheet or food packaging container produced will be excellent. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a flowchart showing an outline of a recycling process for RP materials according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing a sorting and treatment device for RP materials for food packaging containers taken out from used food packaging containers according to an embodiment of the present invention. [Figure 3] 3 is a flowchart for detecting and processing the PP resin material, PE resin material, and talc in the RP material removed from the used packaging container of FIG. 2, as well as the amount of each component. [Figure 4] 4 is a diagram showing the results of the process shown in FIG. 3 when the RP material (recycled material) extracted from the used packaging container of FIG. 2 is made of PP resin material alone. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described. In this embodiment, a food packaging sheet (for example, thickness: 0.4 mm, layer structure: surface layer / middle layer (base layer) / surface layer, layer ratio 1.0 / 98.0 / 1.0) is first produced by extrusion molding. The food packaging sheet may be a single layer other than those described above, or a laminate of four or more layers. Furthermore, the thickness and layer ratio are not limited to those described above. Here, the sheet also includes a film-like sheet. The food packaging sheet described above is formed by vacuum forming or vacuum pressure forming into lunch boxes (containers for storing food (container dimensions: approximately 235mm long x 174mm short x 34mm deep) and a transparent lid to cover it) that are sold in supermarkets (retail stores) etc. Note that the use is not necessarily limited to lunch box containers, and other containers such as salad containers can also be used.

[0016] The food packaging sheet may be configured as a single-layer sheet, but in the case of a food packaging sheet that directly packages food, the sheet layer that comes into contact with the food is preferably a sheet layer made of virgin resin material (e.g., PP resin material) (i.e., a sheet that does not use recycled material). A typical food packaging sheet that directly packages food is preferably configured in such a way that a sheet layer made of RP resin material is placed in the middle (intermediate layer), and sheet layers made of virgin resin material (e.g., PP resin material) are placed as surface layers (surface sheet layers) so as to sandwich the sheet layer (intermediate layer) from above and below.

[0017] Examples of molding methods for food packaging sheets and containers include known molding methods commonly used for known resin materials, etc. Specific examples include extrusion molding, vacuum molding (vacuum pressure molding, plug-assist molding, etc.), injection molding, ultra-high speed injection molding, injection compression molding, two-color molding, gas-assisted and other blow molding methods, molding using an insulated mold, molding using a rapidly heated mold, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding), thermoforming, rotational molding, laminate molding, press molding, and blow molding. Furthermore, the molding conditions for molding the resin material, etc., are not particularly limited, and can be determined appropriately depending on the type of resin material.

[0018] Next, the resin material of the food packaging container of this embodiment will be described. Resin materials for food packaging containers are assumed to be PP resin, PE resin, or talc (an example of an inorganic filler) in addition to being used under regulations such as the Food Sanitation Act, in order to reduce the manufacturing cost of the container and to facilitate mass production, mass consumption, and mass disposal. PP resin generally has low manufacturing costs, excellent mechanical properties, transparency, and excellent chemical resistance and processability. However, it has drawbacks such as poor impact resistance and low-temperature embrittlement.

[0019] Many methods have been proposed to address these drawbacks of PP resin, including blending PP with PE resin. This is based on the idea that compounding PO-based resins (combining PP with PE) improves the mechanical properties of the composite material as a whole. However, there is a concern that PO-based resins (combining PP with PE) may become too hot during incineration, potentially damaging incinerators. To address this concern, inorganic fillers are sometimes added to PO-based resins (combining PP with PE) to reduce combustion calories and prevent incinerator damage. When inorganic fillers are added to PO-based resins (combining PP with PE), the elastic modulus, electrical conductivity, heat resistance, and flame retardancy of molded products made from these resins are improved, increasing safety even when heated in a microwave oven or other device.

[0020] Under these circumstances, if the inorganic filler content is low, the rigidity of molded articles made from resin materials, etc. tends to decrease. On the other hand, if the inorganic filler content is high, the weight of molded articles made from resin materials, etc. increases, making it impossible to meet the demand for lightweight food packaging containers during mass transportation. Under these circumstances, the inventors conducted extensive trial and error research into the content when molding from PO resin materials (PP resin blended with PE resin materials), etc., and found that when the mixing ratios of the PP resin component, PE resin component, and inorganic filler component were 0%, 30%, and 30%, they exhibited excellent results in terms of the above-mentioned manufacturing cost, mechanical properties, electrical properties, light weight, chemical resistance, processing properties, etc., and were therefore suitable as mixing ratios of the PP resin component, PE resin component, and inorganic filler component for food packaging containers. Examples of inorganic fillers include powders of carbonates, sulfates, silicates, phosphates, borates, oxides, or hydrates of calcium, magnesium, titanium, aluminum, iron, zinc, etc. Specific examples include calcium carbonate, magnesium carbonate, zinc oxide, titanium oxide, silica, alumina, clay, talc, potassium hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, calcium silicate, aluminum sulfate, magnesium sulfate, calcium sulfate, magnesium phosphate, barium sulfate, silica sand, carbon black, zeolite, molybdenum, diatomaceous earth, sericite, shirasu, calcium sulfite, sodium sulfate, potassium titanate, bentonite, wollastonite, dolomite, and graphite. These may be contained alone or in combination of two or more.

[0021] In this embodiment, FIG. 1 shows an overview of the recycling process for RP materials. First, used packaging containers (hereinafter simply referred to as "containers" in FIG. 1) are collected from the market (S1). Various plastic resin materials are used for food packaging containers, such as polypropylene (PP)-based resin, polyethylene terephthalate (PET)-based resin, and polystyrene (PS)-based resin. This application assumes that used packaging containers primarily composed of polypropylene (PP)-based resin have already been sorted and collected at the time of collection. If food packaging containers made of different materials are mixed, they may be appropriately sorted using infrared spectroscopy or the like. The collected used packaging containers must be debrided to determine the material composition and performance of the resin material (S2). The method for debriding is not particularly limited, and may include visual debriding or wind power debriding. Furthermore, the collected packaging containers must be washed (S3) in order to detect the material components and material properties of the resin material. The used packaging containers that have been cleaned and washed must be finely crushed (S4) in order to detect the material components and material properties. It does not matter which step (S3) of washing the containers and the step (S4) of crushing the containers are performed first. Furthermore, the washed containers or crushed material may be subjected to a process to remove moisture by natural drying or using a dryer. Generally, crushing requires reducing the size to a predetermined size (for example, about 30 mm). Specifically, if the crushed recycled material is larger than the screen mesh, it will be stopped by the screen mesh, while crushed recycled material smaller than the screen mesh can pass through the screen mesh. When the crushed recycled material reaches a size that roughly matches the mesh size, the size of the crushed recycled material is standardized. In the case of resin material (crushed recycled material) with a standardized size, if the components and component ratios of the resin material (crushed recycled material) are known, the weight of each component contained in the resin material can be determined because the size and specific gravity are known in advance.

[0022] Crushed recycled plastic materials (including resin materials, etc.) (hereinafter also referred to as "crushed RP materials, etc.") obtained from crushed food packaging containers are sorted in a sorting processing device 1 shown in Figure 2. (In Figure 1, this sorting process is referred to as primary sorting (S5).) Then, after the primary sorting (S5) shown in Figure 1, secondary sorting (S6) is carried out. In the case of this embodiment, secondary sorting (S6) involves processing of PP resin materials, PE resin materials, and talc, etc., as shown in Figure 3.

[0023] The pulverized RP material A1 proceeds to step S5 (sorting process shown in FIG. 2) immediately after step S4 shown in FIG. 1. However, prior to step S5, a density-difference sorting method (liquid specific gravity sorting, wet specific gravity sorting) or other process may be performed. For liquid specific gravity sorting, it is desirable to use water, which has a specific gravity of 1, to sort the pulverized RP material. By performing liquid specific gravity sorting using water, pulverized RP material with a specific gravity less than 1 floats to the surface, while pulverized RP material with a specific gravity greater than 1 sinks, making sorting possible. Alternatively, a liquid with a specific gravity less than 1 can be obtained by mixing water with alcohol. Increasing the ratio of alcohol to water reduces the specific gravity of the mixed liquid; alcohol alone has a specific gravity of approximately 0.80. The liquid used for liquid specific gravity sorting is not particularly limited; it may have a specific gravity greater than or equal to 1. Furthermore, when performing liquid gravity separation, applying vertical vibration to the water tank tends to move heavy crushed RP materials to the bottom and lighter materials to the top, improving separation accuracy. Note that, from the perspective of improving separation accuracy (target density), the density may be set to 1.05 grams per cubic centimeter or more, or 1.1 grams per cubic centimeter or more.

[0024] Crushed RP materials, etc. are processed using a sorting and processing device 1 shown in Figure 2 (this process is the primary sorting). Note that devices other than the sorting and processing device 1 may also be used to separate crushed RP materials, etc. Note that used crushed RP materials, etc. are assumed to be food packaging containers collected from the market, but may also include food packaging containers generated within factories and collected before being released to the market. Depending on the recycling situation, used crushed RP materials, etc. may be obtained only from food packaging containers collected before being released to the market.

[0025] As shown in Figure 2, the sorting device 1 includes a conveyor belt 10 that receives pulverized RP materials A1 falling in the direction of arrow B0. As the conveyor belt 10 moves in the direction of arrow B1, the pulverized RP materials A1 are placed on a loading surface 10A and move in the direction of arrow B1. That is, a belt conveyor system is used in which the conveyor belt 10 moves at a predetermined speed to transport a large amount of pulverized RP materials A1 falling in the direction of arrow B0 within a predetermined time. However, other conveyor systems may also be used to move pulverized RP materials A1 at a predetermined speed in the direction of arrow B1.

[0026] Specifically, the conveyor belt 10 is stretched between a rotating roller 11 on one side (upstream side) and a rotating roller 12 on the other side (downstream side), and both rotating rollers 11 and 12 rotate in a predetermined direction so that the loading surface 10A of the conveyor belt 10 moves in the direction of arrow B1. In this case, both rotating rollers 11 and 12 rotate at a predetermined speed under the control of a sorting control device (not shown), and thereby the loading surface 10A of the conveyor belt 10 moves in the direction of arrow B1 at the predetermined speed.

[0027] In this way, as the loading surface 10A of the conveyor belt 10 moves in the direction of arrow B1, the pulverized RP material A1 loaded on the loading surface 10A moves at a predetermined speed from the rotating roller 11 on one side (upstream side) to the rotating roller 12 on the other side (downstream side). A plastic sorting device 13 (hereinafter also referred to as P sorting device 13 for short) is disposed above the loading surface 10A of the conveyor belt 10, between the rotating rollers 11 and 12. The P sorting device 13 is configured to determine the components (materials) and component ratios of the pulverized RP material A1.

[0028] In this case, the P sorting device 13 preferably employs Raman spectroscopy, but an image identification method or the like may also be used in combination. Raman spectroscopy evaluates substances using Raman scattered light, and utilizes the principle that when light (laser light) is irradiated onto a substance, the light interacts with the substance, causing the emission of Raman scattered light with a different wavelength from the incident light. Identification devices using Raman spectroscopy generally consist of a light source, a spectroscope, and a detector, but as these are well known, detailed explanations will be omitted. The signal obtained by spectroscopy is a Raman spectrum, with the horizontal axis representing wavelength and the vertical axis representing intensity, and the sharp peaks that appear in the Raman spectrum are clearly detectable even with short exposure times. Therefore, by analyzing the Raman spectrum, it is possible to detect the P resin material to be measured (for example, P resin materials containing PP resin materials, PE resin materials, and other resin materials, P resin materials containing talc and PP resin materials, and other resin materials, P resin materials containing talc and PE resin materials, and other P resin materials, etc.).

[0029] In this embodiment, talc is often added to PP resin materials and PE resin materials, and component information of these PP resin materials, PE resin materials, and resin materials containing talc is indicated by the phenomenon of peaks in the Raman spectrum. For example, when talc is mixed only with PP resin material, when talc is mixed only with PE resin material, or when talc is mixed into a mixture of PP resin material and PE resin material, each piece of information about the mixture is detected as a unique peak in the Raman spectrum, making it possible to detect detailed component information (i.e., information such as the component ratios of PP resin material, PE resin material, and talc).

[0030] In this case, detailed information on each mixed amount (component ratio) of PP resin material and talc (hereinafter referred to as "information on PP resin material, talc, and component ratio") is detected (hereinafter this detection is referred to as "first detection"). Also, detailed information on each mixed amount (component ratio) of PE resin material and talc (hereinafter referred to as "information on PE resin material, talc, and component ratio") is detected (hereinafter this detection is referred to as "second detection"). Furthermore, detailed information on each mixed amount (component ratio) of PP resin material, PE resin material, and talc (hereinafter referred to as "information on PP resin material, PE resin material, talc, and component ratio") is detected (hereinafter this detection is referred to as "third detection"). To achieve high-precision detection in these first to third detection processes, multivariate analysis is used, which enables comprehensive judgment from the entire spectrum. Discriminant analysis using multivariate analysis uses previously established training data as a basis for classification. In other words, this method sequentially compares the Raman spectrum of reflected light from the resin material to be detected with the Raman spectra of reflected light based on various resin materials registered in advance, and by referencing the matching Raman spectrum, the resin material to be detected (the object to be detected) can be found. Here, analytical methods that utilize molecular vibrations, such as Raman spectroscopy and mid-infrared absorption spectroscopy, are collectively referred to as vibrational spectroscopy.

[0031] An air jet 14 capable of blowing away the pulverized RP material A1 in the direction of arrow B2 is disposed downstream of the P sorting device 13. In this case, the two rotating rollers 11, 12, the P sorting device 13, and the air jet 14 are controlled by a sorting control device (not shown) so as to cooperate with each other. On the arrow B2 side of the rotating roller 12, a proximity sorting area 15 (hereinafter also simply referred to as area 15) is arranged at a position close to the rotating roller 12, and further, a distant sorting area 16 (hereinafter also simply referred to as area 16) is arranged at a position farther from the rotating roller 12. In the proximity sorting area 15, three (multiple) small areas 15A, 15B, 15C are arranged in order according to the distance from the rotating roller 12. In this case, the pulverized RP material A2 blown in the direction of arrow B2 is sorted and controlled by the adjacent area sorting device 18A (described later), and distributed by component and weight to small areas 15A, 15B, and 15C (hereinafter simply referred to as area 15). Note that area 15 does not necessarily have to be in this form (three small areas), and may be, for example, two areas, or four or more areas. Meanwhile, in the remote sorting area 16, three (or more) small areas 16A, 16B, and 16C (hereinafter collectively referred to as simply areas 16) are arranged in order according to the distance from the rotating roller 12. In this case, the remote area sorting device 19A (described later) is sorting controlled, and the pulverized RP material A3 blown in the direction of arrow B2 is distributed to the small areas 16A, 16B, and 16C by component and weight. Note that area 16 does not necessarily have to be in this form (three small areas), and may be, for example, two areas or four or more areas.

[0032] In the near sorting area 15, a near area control device 18 and a near area sorting device 18A are arranged to process the pulverized RP material, etc. A2 that falls into the area 15. Meanwhile, in the far sorting area 16, a far area control device 19 and a far area sorting device 19A are arranged to process the pulverized RP material, etc. A3 that falls into the area 16. The near area control device 18 and the near area selection device 18A are described in a simplified manner for ease of understanding. Similarly, the far area control device 19 and the far area selection device 19A are also described in a simplified manner for ease of understanding. The near area control device 18 and the far area control device 19 may be collectively referred to as a control device. Furthermore, the near area sorting device 18A and the far area sorting device 19A, each controlled by the control device, may be referred to as the sorting device for short. If the configuration is changed to use only crushed RP materials A2 and A3 using the P sorting device 13 and not material A4 (described later), areas 15 and 16 may be configured not to be equipped with control devices 18 and 19 and sorting devices 18A and 19A.

[0033] The near area sorting device 18A is preferably equipped with a Raman spectroscopy device to distribute the pulverized RP material A2 and other materials by component and weight. The far area sorting device 19A is preferably equipped with a Raman spectroscopy device to distribute the pulverized RP material A3 and other materials by component and weight. The sorting devices 18A and 19A may use both Raman spectroscopy and an image identification method, or may use a mid-infrared absorption optical identification method or a near-infrared absorption optical identification method (either one or a combination thereof) in addition to Raman spectroscopy. Further, the near area sorting device 18A is equipped with an air jet type distributor (not shown) to distribute the pulverized RP material, etc. A2 to area 15 by component and weight, but a distributor other than an air jet may also be equipped. The far area sorting device 19A is equipped with an air jet type distributor (not shown) to distribute the pulverized RP material, etc. A3 to area 16 by component and weight, but a distributor other than an air jet may also be equipped.

[0034] In detail, when pulverized RP material etc. A1 moves at a predetermined speed in the direction of arrow B1 on the conveyor belt 10, the P sorting device 13 identifies the material and weight of the pulverized RP material etc. A1 and controls the air jet 14 to spray an appropriate amount of air. In this case, the pulverized RP material etc. A1 moves at a predetermined speed in the direction of arrow B2, and by spraying a small amount of air from the air jet 14, the pulverized RP material etc. A1 falls into the proximity sorting area 15 close to the rotating roller 12 on the other side (downstream side) as pulverized RP material etc. A2 due to its weight (load depending on the components, etc.) and moving speed, etc. Then, based on the first to third detections (i.e., based on information on the component proportions and weights of PP resin material, PE resin material, and talc (inorganic filler material)), the nearby area sorting device 18A distributes the crushed RP material etc. A2 into each of the three areas 15A, 15B, and 15C according to component and weight.

[0035] When a large amount of air is sprayed from the air jet 14, the pulverized RP material A1 is blown far in the direction of arrow B2. In this case, depending on the weight (which depends on the components, etc.) of the pulverized RP material A1 and the moving speed, the pulverized RP material A1 falls as pulverized RP material A3 into the far sorting area 16 (areas 16A, 16B, 16C) far away from the rotating roller 12 on the other side (downstream side). Then, based on the first to third detections (i.e., based on information on the component ratios and weights of PP resin material, PE resin material, and talc), the remote area sorting device 19A distributes the crushed RP material, etc. A3 to each of the three areas 16A, 16B, and 16C according to component and weight. In this way, air from the air jet 14 and the air jet type distributor (not shown) can be used to separate the pulverized RP materials A2, A3 into the near sorting area 15 and the far sorting area 16. As a result, separation of the pulverized RP materials A2, A3 based on information on the component ratio and weight of the resin materials etc. results in a large amount of processing per hour, and the processing efficiency per hour of the pulverized RP materials A2, A3 is high.

[0036] In this case, the pulverized RP material A2 contains a large amount of talc (inorganic filler material), which is heavier than the pulverized RP material A3, and therefore, due to its weight, it falls into the nearby sorting area 15 (15A, 15B, 15C) even when air is sprayed from the air jet 14. On the other hand, if the pulverized RP material A3 is made of a RP resin material with a low specific gravity, when air is sprayed from the air jet 14, it falls into the distant sorting area 16 (areas 16A, 16B, 16C) away from the rotating roller 12 on the other side (downstream) because of its light weight. An RP resin material with a low specific gravity is, for example, one that contains a large amount of PP resin material and PE resin material and contains only a small amount of talc (inorganic filler material), which is heavy, or one that contains almost no talc (inorganic filler material), which is heavy.

[0037] In this embodiment, the proximity area control device 18 can control the operation of the proximity area sorting device 18A to process the pulverized RP material, etc. A2. That is, the proximity area sorting device 18A can sort out the PP resin material components, PE resin material components, and talc contained in the pulverized RP material, etc. A2, and detect the amounts of each of the PP resin material components, PE resin material components, and talc components. At this time, the proximity area control device 18 is configured to supply the required amount of material A4 (described below) in the direction of arrow B3 depending on the processing status (necessary). That is, material A4 falling in the direction of arrow B3 is supplied in a form in which the PP resin material, PE resin material, and talc are separated, and therefore, by controlling the operation of the proximity area sorting device 18A by the proximity area control device 18, it is possible to feed a predetermined amount of each of the PP resin material, PE resin material, and talc into each of the areas 15A, 15B, and 15C. In this case, the material A4 fed into each area 15 is based on the information on the component proportions and weights of the pulverized RP material etc. A2, and is fed with the goal of ultimately achieving a predetermined mixing ratio of each component of PP resin material, PE resin material, and talc (inorganic filler material) (PP resin material: 35-50%, PE resin material: 5-35%, inorganic filler material: 30-55%) for all the resin material stored in each area 15. Here, the PE resin material and talc (inorganic filler material) of the fed material A4 may be in a separate state, or may be pre-mixed (blended) in a so-called master batch (MB) state.

[0038] Furthermore, the remote area control device 19 can control the operation of the remote area sorting device 19A to process the pulverized RP material, etc. A3. That is, the remote area sorting device 19A can sort out the PP resin material, PE resin material, and talc contained in the pulverized RP material, etc. A3, and detect the amounts of each of the PP resin material, PE resin material, and talc components.

[0039] At this time, the remote area control device 19 is configured to be able to supply the required amount of material A4 in the direction of arrow B3 according to the processing status (necessary). That is, material A4 falling in the direction of arrow B3 is supplied in a form in which the PP resin material, PE resin material, and talc are separated along the direction of arrow B3, and therefore the remote area control device 19 can control the operation of the remote area sorting device 19A to feed a predetermined amount of each of the PP resin material, PE resin material, and talc into each of areas 16A, 16B, and 16C.

[0040] In this case, the material A4 fed into each area 16 is based on the information on the component ratio and weight of the crushed RP material etc. A3, with the goal that the components of the PP resin material, PE resin material and inorganic filler material will ultimately reach a predetermined mixing ratio (for example, the mixing ratio in the embodiment) for all the resin material stored in each area 16. As a result, the pulverized RP materials A2 and A3 are sorted and fed into areas 15 and 16 (sorting process) based on the information on component proportions and weights. Furthermore, when the pulverized RP materials A2 and A3 are mixed with material A4 (virgin resin material and new material), the content of each of the materials (PP resin material, PE resin material, and talc) stored in areas 15 and 16 is detected (detection process) based on the information on component proportions and weights.

[0041] Here, the examples of Fig. 4 will be described. Example 1 is a condition in which containers collected from the market are crushed, washed, and dried, and then subjected to liquid gravity sorting with water, without performing vibrational spectroscopy (Raman spectroscopy, mid-infrared absorption). On the other hand, Example 2 is a condition in which containers collected from the market are crushed, washed, and dried, and then subjected to vibrational spectroscopy (Raman spectroscopy, mid-infrared absorption) without performing liquid gravity sorting with water.

[0042] In Example 1, the predetermined mixing ratio for food packaging containers is set to 50%, 20%, and 30% for PP resin material, PE resin material, and talc (inorganic filler material), respectively. In Example 1 (RP resin 20%) shown in Figure 4, the detected content of PP resin (recycled material) is 20%. In this case, by comparing the detection result (PP resin 20%) with the mixing ratios for food packaging containers (50%, 20%, and 30%), which are predetermined mixing ratios of PP resin, PE resin, and talc (inorganic filler), it is possible to add a predetermined amount of missing PP resin (virgin resin), a predetermined amount of missing PE resin (virgin resin), and a predetermined amount of missing inorganic filler (new material) based on the comparison result. That is, a predetermined amount of one or more of the missing components (PP resin, PE resin, and talc) is added so that the detection result (20% PP resin) becomes the mixing ratio for food packaging containers (50%, 20%, and 30%), and the final mixing ratio approaches a target mixing ratio of 50% PP resin, 20% PE resin, and 30% talc. Note that the above-mentioned comparing and adding modes correspond to the comparing step and adding step, but other modes may also be adopted.

[0043] In Example 1 (RP resin material 20%), the sorting devices 18A and 19A supply a predetermined amount of missing PP resin material (virgin resin material), a predetermined amount of missing PE resin material (virgin resin material), and a predetermined amount of missing talc (new material) from the material A4 supplied in the direction of arrow B3. In this case, the amount of PP resin material (virgin resin material) is 30%, the amount of PE resin material (virgin resin material) is 20%, and the amount of talc (new material) is 30%.

[0044] Areas 15 and 16 shown in FIG. 2 store predetermined amounts of PP resin material, PE resin material, and talc, so that the predetermined amount of PP resin material is 50%, the predetermined amount of PE resin material is 20%, and the predetermined amount of talc is 30%. As a result, the resin materials stored in areas 15 and 16 have a mixture ratio of 50% PP resin material component, 20% PE resin material component, and 30% talc component, which is a desirable mixture ratio for resin materials contained in food packaging containers.

[0045] In Example 2, the predetermined mixing ratio for food packaging containers is set to 50%, 20%, and 30% for PP resin material, PE resin material, and talc (inorganic filler material), respectively. In Example 2 (40% RP resin) shown in Figure 4, the PP resin (recycled material) is 40%. In this case, by comparing the detection result (40% PP resin) with the mixing ratios for food packaging containers (50%, 20%, and 30%), which are predetermined mixing ratios of PP resin, PE resin, and talc, it is possible to add a predetermined amount of missing PP resin (virgin resin), a predetermined amount of missing PE resin (virgin resin), and a predetermined amount of missing talc (new material) based on this comparison result.

[0046] That is, in the case of Example 2 (40% RP resin material), sorting devices 18A and 19A supply material A4 along the direction of arrow B3 so that the material A4 is supplied in a predetermined amount of the missing PP resin material (virgin resin material), the missing PE resin material (virgin resin material), and the missing talc (new material) (i.e., the content of PP resin material is 50%, the content of PE resin material is 20%, and the content of talc is 30%).

[0047] In this case, areas 15 and 16 will contain predetermined amounts of PP resin (a mixture of new and recycled materials), PE resin (a mixture of new and recycled materials), and talc (a mixture of new and recycled materials) so that the PP resin component (a mixture of new and recycled materials) is 50%, the PE resin (a mixture of new and recycled materials) is 20%, and the talc (a mixture of new and recycled materials) is 30%. As a result, the resins, etc. stored in areas 15 and 16 will have the desired mixture ratios (50%, 20%, and 30%) for use in resins, etc. for food packaging containers.

[0048] In Example 3, the predetermined mixing ratio for food packaging containers is set to 40%, 5%, and 55% for PP resin material, PE resin material, and talc (inorganic filler material), respectively. In Example 3 (RP resin 20%) shown in Figure 4, the detected content of PP resin (recycled material) is 20%. In this case, by comparing the detection result (PP resin 20%) with the mixing ratios for food packaging containers (40%, 5%, and 55%), which are predetermined mixing ratios of PP resin, PE resin, and talc (inorganic filler), it is possible to add a predetermined amount of missing PP resin (virgin resin), a predetermined amount of missing PE resin (virgin resin), and a predetermined amount of missing inorganic filler (new material) based on the comparison result. That is, a predetermined amount of one or more of the missing components (PP resin, PE resin, and talc) is added so that the detection result (20% PP resin) becomes the mixing ratio for food packaging containers (40%, 5%, and 55%), and the final mixing ratio approaches a target mixing ratio of 50% PP resin, 5% PE resin, and 55% talc. Note that the above-mentioned comparing and adding modes correspond to the comparing step and adding step, but other modes may also be adopted.

[0049] In Example 3 (RP resin material 20%), the sorting devices 18A and 19A supply a predetermined amount of missing PP resin material (virgin resin material), a predetermined amount of missing PE resin material (virgin resin material), and a predetermined amount of missing talc (new material) from the material A4 supplied in the direction of arrow B3. In this case, the amount of PP resin material (virgin resin material) is 20%, the amount of PE resin material (virgin resin material) is 5%, and the amount of talc (new material) is 55%.

[0050] Areas 15 and 16 shown in FIG. 2 store predetermined amounts of PP resin material, PE resin material, and talc, so that the predetermined amount of PP resin material is 40%, the predetermined amount of PE resin material is 5%, and the predetermined amount of talc is 55%. As a result, the resin materials stored in areas 15 and 16 have a mixture ratio of 40% PP resin material component, 5% PE resin material component, and 55% talc component, which is a desirable mixture ratio for resin materials contained in food packaging containers.

[0051] In Example 4, the predetermined mixing ratio for food packaging containers is set to 40%, 5%, and 55% for PP resin material, PE resin material, and talc (inorganic filler material), respectively. In Example 4 (RP resin 40%) shown in Figure 4, the detected content of PP resin (recycled material) is 40%. In this case, by comparing the detection result (PP resin 40%) with the mixing ratios for food packaging containers (40%, 5%, and 55%), which are predetermined mixing ratios of PP resin, PE resin, and talc (inorganic filler), it is possible to add a predetermined amount of missing PP resin (virgin resin), a predetermined amount of missing PE resin (virgin resin), and a predetermined amount of missing inorganic filler (new material) based on the comparison result. That is, a predetermined amount of one or more of the missing components (PP resin, PE resin, and talc) is added so that the detection result (40% PP resin) becomes the mixing ratio for food packaging containers (40%, 5%, and 55%), and the final mixing ratio approaches a target mixing ratio of 40% PP resin, 5% PE resin, and 55% talc. Note that the above-mentioned comparing and adding modes correspond to the comparing step and adding step, but other modes may also be adopted.

[0052] In Example 4 (RP resin material 40%), the sorting devices 18A and 19A supply a predetermined amount of missing PP resin material (virgin resin material), a predetermined amount of missing PE resin material (virgin resin material), and a predetermined amount of missing talc (new material) from the material A4 supplied in the direction of arrow B3. In this case, the amount of PP resin material (virgin resin material) is 40%, the amount of PE resin material (virgin resin material) is 5%, and the amount of talc (new material) is 55%.

[0053] Areas 15 and 16 shown in FIG. 2 store predetermined amounts of PP resin material, PE resin material, and talc, so that the predetermined amount of PP resin material is 40%, the predetermined amount of PE resin material is 5%, and the predetermined amount of talc is 55%. As a result, the resin materials stored in areas 15 and 16 have a mixture ratio of 40% PP resin material component, 5% PE resin material component, and 55% talc component, which is a desirable mixture ratio for resin materials contained in food packaging containers.

[0054] The above-described comparison and addition modes correspond to the comparison step and addition step, but other modes may also be employed.

[0055] It is desirable to crush and wash the containers collected from the market, and then perform liquid gravity sorting and vibrational spectroscopy (Raman spectroscopy, mid-infrared absorption). The sheets and / or containers for which physical properties such as flexural modulus have been measured may be crushed again, washed, and then subjected to liquid gravity sorting and vibrational spectroscopy (Raman spectroscopy, mid-infrared absorption).

[0056] When the RP resin content is 100%, comparative experiments have shown that situations can occur where the food packaging mix ratio is not achieved, i.e., the PP resin component is not at the specified ratio (e.g., 50%), the PE resin component is not at the specified ratio (e.g., 30%), and the talc component is not at the specified ratio (e.g., 30%). In these situations where the food packaging mix ratio is not achieved, new material A4 (PP resin, PE resin, and talc) is not supplied along the direction of arrow B3, so new PP resin, new PE resin, and new talc are not supplied to areas 15 and 16. In this case, the PP resin, PE resin, and talc contained in areas 15 and 16 do not achieve the desired mix ratio.

[0057] Regarding the crushed RP materials A2, A3 that fall into the above-mentioned sorting areas 15, 16, the sorting devices 18A, 19A can grasp the components and amounts of PP resin material, PE resin material, and talc under the control of the control devices 18, 19. Furthermore, the sorting devices 18A, 19A are configured to be able to grasp the components of PP resin material, PE resin material, and talc, respectively, in a state where the crushed RP materials A2, A3 are mixed with new material A4 (mixed state), as well as to grasp the amounts of the components of PP resin material, PE resin material, and talc, respectively.

[0058] Next, the control of the control devices 18 and 19 will be explained using Fig. 3. In Fig. 3, in the processing of the pulverized RP material A2 and A3, the area control devices 18 and 19 first detect whether or not the material contains a PP resin component (S11) in order to separate the PP resin component, the PE resin component, and the talc component. This detection process corresponds to the PP sorting process.

[0059] That is, it is determined whether or not the pulverized RP materials A2, A3 contain PP resin components, and if it is determined that the pulverized RP materials A2, A3 do not contain PP resin components (NO in S11), it is detected whether or not the pulverized RP materials A2, A3 contain PE resin components (S12). This detection process corresponds to the PE sorting process.

[0060] If it is determined that the pulverized RP material A2, A3 does not contain talc components (NO in S12), it is detected whether the pulverized RP material A2, A3 contains talc components (NO in S13), and it is detected whether the pulverized RP material A2, A3 contains PP resin components (S11).

[0061] Here, if the crushed RP materials A2, A3 contain PP resin material components (YES in S11), the control devices 18, 19 can detect the amount of PP resin material components (S14) and can perform a comparison and addition process regarding the amount of PP resin material components (S15).

[0062] Similarly, if the pulverized RP materials A2, A3 contain a PE resin component (YES in S12), the control devices 18, 19 can detect the amount of the PE resin component (S16) and perform a comparison and addition process for the amount of the PE resin component (S17). Also, if the pulverized RP materials A2, A3 contain talc (YES in S13), the control devices 18, 19 can detect the amount of the talc component (S18) and perform a comparison and addition process for the amount of the talc component (S19).

[0063] The order of determining whether or not the material contains a PP resin component (S11), whether or not the material contains a PE resin component (S12), and whether or not the material contains a talc component (S13) is not limited to this order. That is, the order may be the PP sorting step, the talc sorting step, and the PE sorting step. The order may also be the PE sorting step, the talc sorting step, and the PP sorting step, or the PE sorting step, the PP sorting step, and the talc sorting step. The order may also be the talc sorting step, the PE sorting step, and the PP sorting step, or the talc sorting step, the PP sorting step, and the PE sorting step.

[0064] The performance evaluation of the food packaging containers and food packaging sheets yielded the results shown in Figure 4. The sheet flexural modulus was measured using an Autograph AGS-X manufactured by Shimadzu Corporation in accordance with JIS (Japanese Industrial Standards) K7171 under the following measurement conditions: distance between supports: 30 mm, bending speed: 20 mm / min. Regarding the flexural modulus, the flexural modulus (MD) of Examples 1 to 4 in FIG. 4 was 3451, 3170, 3829, and 3763 MPa, respectively. As a result, it was found that the flexural modulus was over 1100 MPa, providing sufficient mechanical strength. In contrast, in a comparative experiment, when the RP resin material was 100%, the flexural modulus (MD) was 800 MPa, below 1100 MPa, indicating insufficient mechanical strength. Here, MD refers to the flow direction in which the resin (sheet) is extruded during extrusion molding.

[0065] The material density can be measured using an electronic hydrometer SD-200L (manufactured by Alpha Mirage Co., Ltd.) according to the density and specific gravity measurement method (JIS K7112). The densities of Examples 1 to 4 in Figure 4 were 1.15, 1.14, 1.42, and 1.41 grams per cubic centimeter, respectively, and since the densities (target densities) were 1 or more, it was found that specific gravity separation using water was possible from materials with densities less than 1.

[0066] A drop test was conducted to assess the container's physical properties. A 250 g weight was placed inside the container, and the thermoformed lid was placed on top. The container was then stored for 24 hours at 23°C. Then, the containers were dropped from a height of 1 m (n=10) in the same atmosphere, and the containers were visually inspected for cracks and the number of broken pieces was counted. In the experimental results of Examples 1 to 4 regarding the drop test shown in Figure 4, none of them were broken. On the other hand, in a comparative experiment, when the RP resin material was 100%, and the PP resin material component, PE resin material component, and inorganic filler material component were not in the specified ratio (i.e., the mixture ratio for food packaging was not reached), 5 out of 10 pieces were broken. This shows that Examples 1 and 2 have excellent impact resistance.

[0067] According to the above-described embodiment, the method includes a detection step (S14) for detecting the amount of PP resin in the pulverized RP materials A2 and A3 obtained from used packaging containers, a comparison step (S15, S17, S19) for comparing the result of the detection step (S14) with a predetermined mixing ratio for food packaging containers (e.g., an example formulation) of PP resin, PE resin, and talc (inorganic filler), and an addition step (S15, S17, S19) for adding a predetermined amount of one or more of the missing components of PP resin, PE resin, and talc (inorganic filler) based on the comparison results of the comparison steps (S15, S17, S19) so that the result of the detection step (S14) matches the mixing ratio for food packaging containers (e.g., an example formulation). As a result, the final resin materials melted and molded after the addition step exhibit excellent manufacturing costs (low), mechanical and electrical properties, chemical resistance, and processability. Therefore, according to this embodiment, when manufacturing RP materials for food packaging containers removed from used packaging containers, the manufacturing method of the RP material is excellent. Furthermore, by using the excellent manufacturing method of the RP material, the food packaging sheets or food packaging containers manufactured are excellent.

[0068] Furthermore, according to the above embodiment, the RP material for food packaging containers removed from a used packaging container comprises PP resin material, PE resin material and inorganic filler, to which a predetermined amount of one or more of the missing components is added, so that the detection result becomes the mixing ratio for food packaging containers (for example, an example), based on the comparison result of the PP resin material whose content obtained from the RP material for food packaging containers is detected and the detection result of the PP resin material whose content is detected with the mixing ratio for food packaging containers, which is a predetermined mixing ratio of PP resin material, PE resin material and talc (inorganic filler material). Such RP materials for food packaging containers, when melted and molded, exhibit excellent manufacturing costs (low cost), mechanical and electrical properties, chemical resistance, and processing properties. Therefore, the RP materials for food packaging containers removed from used packaging containers are excellent, and the use of such excellent RP materials results in excellent food packaging sheets or food packaging containers. The preferred range of material composition for the final container in the present invention is preferably PP resin material: 35-50%, PE resin material: 5-35%, inorganic filler material: 30-55%, but is not limited to this range. [Explanation of symbols]

[0069] 1... Separation processing device, 10... Conveyor belt, 13... P sorting device, 14. Air jet, 15. Close-up sorting area, 16···Far-field sorting area, 18···Proximity area control device, 19.... Remote area control device, A1, A2, A3...Crushed RP materials, etc. (mixed resin materials, RP materials for food packaging containers), A4... Materials (virgin PP resin, virgin PE resin, virgin talc) B1, B2, B3...arrows, S1: Container collection, S2: Collection container removal, S3: Container cleaning, S4: Crushing of containers, S5: Primary sorting, S6: Secondary sorting, S11: PP detection (PP component detection process) S12: PE detection (PE component detection process), S13: Talc detection (inorganic filler detection process), S14: PP resin component content detection (PP content detection process) S16: PE resin component content detection (PE content detection process) S18: Talc content detection (inorganic filler detection process) S15...Comparison / additional process (comparison process / additional process), S17...Comparison / additional process (comparison process / additional process), S19...Comparison / additional process (comparison process / additional process), PO···Polyolefin (polyolefin-based material component·PO-based material component), PP··· Polypropylene (polypropylene resin material, PP resin material), PE···Polyethylene (polyethylene resin material, PE resin material),

Claims

1. A method for producing recycled plastic materials for food packaging containers by removing the plastic materials from used packaging containers, comprising: a detection step of detecting the content of polypropylene resin material obtained from the recycled plastic material for food packaging containers; a comparison step of comparing the detection result of the polypropylene resin material detected in the detection step with a mixing ratio for a food packaging container in which the polypropylene resin material, the polyethylene resin material, and the inorganic filler material are mixed in a predetermined ratio; and an additional step of adding a predetermined amount of one or more of the missing components from among polypropylene resin material, polyethylene resin material, and inorganic filler material, based on the comparison result of the comparison step, so that the detection result becomes the mixing ratio for food packaging containers.

2. 3. The method for producing recycled plastic materials according to claim 2, wherein the target density of the recycled plastic material after the addition step is completed and the melt-kneaded material is 1 gram per cubic centimeter or more.

3. A food packaging sheet or food packaging container manufactured using the method for manufacturing recycled plastic material according to any one of claims 1 and 2.

4. A recycled plastic material for food packaging containers removed from used packaging containers, a polypropylene resin material obtained from the recycled plastic material for food packaging containers, the content of which is detectable; and A recycled plastic material characterized by comprising polypropylene resin material, polyethylene resin material and inorganic filler, in which a predetermined amount of one or more of the missing components is added so that the detection result becomes the mixing ratio for food packaging containers, based on the comparison result obtained by comparing the detection result of the polypropylene resin material whose content has been detected with a mixing ratio for food packaging containers in which polypropylene resin material, polyethylene resin material and inorganic filler material are mixed in a predetermined ratio.

5. 5. The recycled plastic material according to claim 4, wherein the target density of the recycled plastic material after melt-kneading is 1 gram per cubic centimeter or more.

7. A food packaging sheet or food packaging container manufactured using the recycled plastic material of any one of claims 4 and 5.

Images