Recycling system, recycling method, and storage medium

Abstract

To provide a recycling system capable of stabilizing a quality of a recycled product.SOLUTION: A recycling system comprises: a quality determination section 710 that determines based on predetermined quality determination criteria a quality of a solid material of PET flakes, etc. including a polymer being a recycled object; a material sorting section 720 that sorts the solid material into a high quality material determined to be of a quality above the quality determination criteria and into a low quality material determined to be of a quality below the quality determination criteria; a mechanical recycling device 900 that subjects the high quality material to mechanical recycling processing; and a chemical recycling device 100 that subjects the low quality material to chemical recycling processing. The chemical recycling device 100 includes: a depolymerization reaction tank 300 that decomposes the low quality material into a depolymerized product by a depolymerization reaction; foreign matter elimination devices 340 to 360 that eliminate a foreign matter from the depolymerized product; a polymerization reaction tank 400 that synthesizes a polymer from the depolymerized product by a polymerization reaction; and a polymerization acceleration device 500 that heightens a degree of polymerization of the polymer.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a recycling system. [Background technology]

[0002] Patent Document 1 discloses a method for recycling PET (polyethylene terephthalate) bottles by crushing the PET bottles to produce PET flakes that serve as raw materials for new PET bottles. Specifically, known methods include mechanical recycling, in which crushed PET bottles are heated and melted, and then PET flakes are obtained by solid-phase polymerization, and chemical recycling, in which crushed PET bottles are decomposed into intermediates such as bis(2-hydroxyethyl) terephthalate (BHET) or depolymerized polymers by a depolymerization reaction, and then PET flakes are obtained by a repolymerization reaction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-153176 A [Patent Document 2] Patent Publication No. 2022-27158 Summary of the Invention [Problem to be solved by the invention]

[0004] The quality of the above-mentioned PET flakes and PET pellets (hereinafter referred to simply as flakes and pellets, and also including flakes and pellets that are not made from PET) depends on the quality of their raw materials, PET bottles, etc. Even if the same recycling process (mechanical or chemical recycling process) is applied to flakes and pellets, which can vary in quality, PET bottles, etc. will be produced with unstable quality.

[0005] The present disclosure has been made in consideration of these circumstances, and aims to provide a recycling system etc. that can stabilize the quality of recycled products. [Means for solving the problem]

[0006] In order to solve the above problems, a recycling system according to one embodiment of the present disclosure includes a quality determination unit that determines the quality of a solid material, including a polymer, to be recycled based on predetermined quality determination criteria; a material sorting unit that sorts the solid material into high-quality materials determined to have a higher quality than the quality determination criteria and low-quality materials determined to have a lower quality than the quality determination criteria; a mechanical recycling device that performs a mechanical recycling process on the high-quality materials; and a chemical recycling device that performs a chemical recycling process on the low-quality materials.

[0007] In this embodiment, solid materials are sorted into high-quality materials and low-quality materials based on quality criteria. The high-quality materials are efficiently recycled by mechanical recycling, which has a low quality improvement effect but requires simple equipment, and the low-quality materials are recycled while their quality is improved by chemical recycling, which has a high quality improvement effect. Thus, according to this embodiment, the quality of the recycled products can be stabilized by applying an appropriate recycling process (mechanical recycling or chemical recycling) according to the quality of the solid materials.

[0008] Another aspect of the present disclosure is a recycling method that includes, via a computer, determining the quality of a solid material to be recycled based on a predetermined quality criterion, sorting the solid material into high-quality materials determined to have a quality higher than the quality criterion and low-quality materials determined to have a quality lower than the quality criterion, subjecting the high-quality materials to a mechanical recycling process, and subjecting the low-quality materials to a chemical recycling process.

[0009] Yet another aspect of the present disclosure is a storage medium that stores a recycling program that causes a computer to execute the following operations: determining the quality of solid materials to be recycled based on a predetermined quality criterion; sorting the solid materials into high-quality materials determined to have a quality higher than the quality criterion and low-quality materials determined to have a quality lower than the quality criterion; subjecting the high-quality materials to a mechanical recycling process; and subjecting the low-quality materials to a chemical recycling process.

[0010] Any combination of the above components, or any conversion of these components into a method, device, system, recording medium, computer program, or the like, is also encompassed by the present disclosure. Effect of the Invention

[0011] According to the present disclosure, the quality of recycled products can be stabilized. [Brief description of the drawings]

[0012] [Figure 1] The configuration of the chemical recycling molding system is shown diagrammatically. [Diagram 2] The polymerization and depolymerization reactions of PET are shown diagrammatically. [Diagram 3] 1 shows a schematic diagram of a horizontal stirring device. [Figure 4] 13A and 13B are schematic diagrams showing a configuration of a chemical recycling molding system according to a modified example. [Diagram 5] 2 shows a schematic diagram of a recycling system according to a second embodiment. [Figure 6] 13 shows a schematic diagram of a quality assessment unit and a material selection unit that are substantially integrally configured. [Figure 7] 13 is a schematic diagram showing a recycling system according to a third embodiment. [Figure 8] 1 shows a schematic diagram of a partial depolymerization section and a solid-liquid separation section that are configured substantially integrally. [Figure 9] 9 shows a schematic diagram of a modification of the processing apparatus shown in FIG. 8. [Figure 10]9 shows a schematic diagram of a modification of the processing apparatus shown in FIG. 8. [Figure 11] 9 shows a schematic diagram of a modification of the processing apparatus shown in FIG. 8. [Figure 12] 8 shows a schematic configuration of a recycle system according to a modified example of FIG. 7. [Figure 13] The depolymerization reaction is shown diagrammatically. [Figure 14] 1 shows a schematic diagram of a first embodiment of a mechanical mixer; [Figure 15] 2 illustrates a schematic diagram of a second embodiment of the mechanical mixer; [Figure 16] 13 illustrates a schematic diagram of a third embodiment of the mechanical mixer; [Figure 17] 13 illustrates a fourth embodiment of the mechanical mixer; [Figure 18] 13 shows a schematic diagram of a recycling system according to a fourth embodiment. [Figure 19] 13 shows a schematic diagram of a recycling system according to a fifth embodiment. [Figure 20] 13 is a schematic diagram showing a recycling system according to a sixth embodiment. [Figure 21] 13 is a schematic diagram showing a recycling system according to a seventh embodiment. [Figure 22] 13 is a schematic diagram showing a recycling system according to an eighth embodiment. [Diagram 23] 13 shows a schematic diagram of a recycling system according to a ninth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In the following, a form for carrying out the present disclosure (hereinafter also referred to as an embodiment) will be described in detail with reference to the drawings. In the description and / or drawings, identical or equivalent components, members, processes, etc. will be given the same reference numerals, and duplicated descriptions will be omitted. The scale and shape of each part shown in the drawings are set for convenience in order to simplify the description, and are not to be interpreted as being limiting unless otherwise specified. The embodiment is an example, and does not limit the scope of the present disclosure in any way. All features and their combinations presented in the embodiment are not necessarily essential to the present disclosure. The embodiment is presented for convenience, decomposed into components for each function and / or each functional group that realizes it. However, one component in the embodiment may actually be realized by a combination of multiple components as separate entities, and multiple components in the embodiment may actually be realized by one component as an integrated entity.

[0014] FIG. 1 is a schematic diagram showing the configuration of a chemical recycle molding system as one embodiment of the recycle system according to the present disclosure. As described later, the recycle system according to the present disclosure may be configured as a mechanical recycle molding system, or may be configured as a hybrid recycle molding system equipped with both a chemical recycle device and a mechanical recycle device. In addition, the recycle molding system (chemical recycle molding system) illustrated in FIG. 1 includes a recycle device (chemical recycle device 100) and a molding machine (injection molding machine 1), but the recycle system according to the present disclosure does not have to include a molding machine.

[0015] The chemical recycling molding system shown in Fig. 1 includes a chemical recycling apparatus 100 and an injection molding machine 1. The chemical recycling apparatus 100 performs a chemical recycling process, which will be described in detail below, on a first molded article such as a PET bottle and / or solid materials such as PET flakes and PET pellets derived from various first molded articles.

[0016] The chemical recycling apparatus 100 includes a polymer adjustment apparatus 200, a depolymerization reaction tank 300, a polymerization reaction tank 400, a polymerization promotion apparatus 500, and a polymer supply section 600. The number of each of the injection molding machines 1 (two of which are shown in FIG. 1 ), polymer adjustment apparatus 200, depolymerization reaction tank 300, polymerization reaction tank 400, polymerization promotion apparatus 500, and polymer supply section 600 may be arbitrarily set. In particular, by increasing the number of the injection molding machines 1 and polymerization reaction tanks 400, which typically have a slower processing speed or reaction speed than the other processing sections, the processing performance can be improved so that these processing sections do not become serious bottlenecks.

[0017] The polymer adjustment device 200 adjusts a polymer such as PET constituting a first molded product such as a PET bottle and / or a solid material such as PET flakes for the subsequent depolymerization reaction tank 300. Specifically, the polymer adjustment device 200 performs processing such as crushing, heat melting, mixing, etc. on the first molded product such as a PET bottle and / or a solid material such as PET flakes, and adjusts the polymer such as PET to a state (phase, shape, size, etc.) suitable for the depolymerization reaction in the depolymerization reaction tank 300. The first molded product may be any molded product other than a bottle, such as a sheet, film, fiber, etc. Furthermore, the polymer constituting the first molded product and / or the solid material may be any polymer or polymer other than PET, such as polyester (including PET), polyamide, polyurethane, etc.

[0018] The polymer adjustment apparatus 200 may perform a process such as pulverization on a first molded product such as a PET bottle to generate a solid material such as PET flakes. In addition, when the depolymerization reaction tank 300 can accept the solid material, such as a pre-fabricated solid material such as PET flakes, may be directly charged into the depolymerization reaction tank 300 without passing through the polymer adjustment apparatus 200. Furthermore, as described later, a quality determination unit that determines the quality of the solid material such as PET flakes, a material sorting unit that sorts the solid material into high-quality material and low-quality material, a partial depolymerization unit that partially decomposes the solid material such as PET flakes, a solid-liquid separation unit that separates the solid and liquid components obtained in the partial depolymerization unit, and the like may be provided in the upstream of the polymer adjustment apparatus 200 and / or the depolymerization reaction tank 300.

[0019] The depolymerization reactor 300 decomposes polymers such as PET to be recycled contained in solid materials such as PET flakes into depolymerized polymers through a depolymerization reaction. When the polymer supplied to the depolymerization reactor 300 is PET, an intermediate BHET is obtained as a depolymer through the depolymerization reaction in the depolymerization reactor 300. The depolymerized polymer obtained in the depolymerization reactor 300 may contain a monomer or monomers of the polymer. When the polymer is PET, the monomer is, for example, ethylene glycol, terephthalic acid, dimethyl terephthalate, or ethylene terephthalate.

[0020] As shown in FIG. 2, in the depolymerization reaction (300) of PET as a polymer, PET is decomposed by ethylene glycol (EG) as a depolymerization agent supplied from the depolymerization agent supply unit 310 (FIG. 1) to the depolymerization reaction tank 300, and BHET as a depolymerization polymer is obtained. Note that EG may be supplied in the polymer adjustment device 200 instead of or in addition to the depolymerization agent supply unit 310. In order to promote such a depolymerization reaction, the inside of the depolymerization reaction tank 300 is maintained at a temperature suitable for the depolymerization reaction by a heater 320 (FIG. 1) or a warmer provided next to the depolymerization reaction tank 300. The temperature suitable for the depolymerization reaction of PET to BHET in FIG. 2 is between 220° C. and 250° C., preferably between 230° C. and 245° C., and more preferably between 235° C. and 240° C. 2, the pressure suitable for the depolymerization reaction of PET to BHET is between 0.3 MPa and 0.8 MPa, preferably between 0.4 MPa and 0.6 MPa, and more preferably between 0.45 MPa and 0.55 MPa. The pressure in the depolymerization reaction tank 300 is adjusted by a pump (not shown) or the like provided in the depolymerization reaction tank 300.

[0021] Since the viscosity of the fluid in the depolymerization reaction tank 300, in which BHET, which has a smaller molecular weight than PET, a polymer, is produced, is lower than the viscosity of the fluid in the polymerization reaction tank 400 described below, in which PET, which has a larger molecular weight, is produced, a low-viscosity agitator blade 330 is used to agitate the fluid in the depolymerization reaction tank 300 and promote the depolymerization reaction. Examples of the low-viscosity agitator blade 330 include a propeller blade, a disk turbine blade, and a paddle blade.

[0022] Foreign matter removal devices 340, 350, 360 are provided downstream of the depolymerization reaction tank 300 to remove foreign matter from the fluid mainly composed of BHET as a depolymerization polymer. The foreign resin removal device 340 removes resins other than the target resin such as PET and / or its depolymerization polymers by the principles of flotation separation and sedimentation removal. The colored matter removal device 350 removes colored matter using activated carbon or the like. The metal ion removal device 360 ​​removes metal ions by the principles of ion exchange or the like. A buffer tank 370 is provided downstream of the foreign matter removal devices 340, 350, 360 to temporarily store the fluid mainly composed of BHET and the like after the foreign matter has been removed before it is supplied to the polymerization reaction tank 400.

[0023] The buffer tank 370 may be provided with a first preheater 371 for heating or keeping warm the depolymerized polymer (a fluid mainly composed of BHET or the like) before it is supplied to the polymerization reaction tank 400 in the downstream. The first preheater 371 may maintain the depolymerized polymer at a temperature (between 220°C and 250°C) similar to that of the heater 320 provided in the depolymerization reaction tank 300, or may maintain the depolymerized polymer at a temperature (between 250°C and 300°C) suitable for polymerization reaction similar to that of the heater 410 provided in the polymerization reaction tank 400 described later. In this way, by providing the buffer tank 370 equipped with a preheating mechanism (first preheater 371) as necessary in the upstream of the polymerization reaction tank 400, the depolymerized polymer waiting to be introduced into the polymerization reaction tank 400, which typically has a slower processing speed or reaction speed than other processing units such as the depolymerization reaction tank 300 and the polymerization promotion device 500 described later, can be stored at an appropriate temperature. As a result, the overall capacity of the chemical recycling apparatus 100 can be increased, and the chemical recycling apparatus 100 can be operated stably and continuously (without causing so-called "resin shortage") while supplying appropriate amounts of reactants at appropriate times to each processing section, such as the depolymerization reaction tank 300, the polymerization reaction tank 400, the polymerization promotion device 500, and the polymer supply section 600. Note that the preheating mechanism such as the first preheater 371 is not limited to the buffer tank 370, and may be provided in any position between the depolymerization reaction tank 300 and the polymerization reaction tank 400 (for example, the foreign matter removal devices 340, 350, 360) in any manner.

[0024] The polymerization reactor 400 synthesizes depolymerized materials such as BHET, which are produced in the depolymerization reactor 300 and from which foreign matter has been removed by the foreign matter removal devices 340, 350, and 360, into polymers through a polymerization reaction. When the depolymerized materials produced in the depolymerization reactor 300 are BHET, the polymer PET is reobtained through a polymerization reaction in the polymerization reactor 400.

[0025] As shown in FIG. 2, in the polymerization reaction (400) of BHET as a depolymerization product, PET as a main product, which is a polymer, and EG as a by-product are produced. This EG may be circulated to the depolymerization agent supply section 310 and used for the depolymerization reaction of PET in the depolymerization reaction tank 300. Since the EG produced in the polymerization reaction tank 400 can be reused on the spot (depolymerization reaction tank 300) without being wasted, the operating efficiency of the chemical recycling apparatus 100 can be improved. In particular, the amount of EG purchased for the depolymerization reaction of PET in the depolymerization reaction tank 300 can be significantly reduced, which leads to a reduction in the operating cost of the chemical recycling apparatus 100.

[0026] In order to promote the above-mentioned polymerization reaction, the inside of the polymerization reaction tank 400 is maintained at a temperature suitable for the polymerization reaction by a heater 410 (FIG. 1) or a warmer as a second heater provided next to the polymerization reaction tank 400. The temperature suitable for the polymerization reaction of BHET to PET in FIG. 2 is between 250° C. and 300° C., preferably between 260° C. and 290° C., and more preferably between 270° C. and 280° C. Here, the polymerization heating temperature by the heater 410 provided next to the polymerization reaction tank 400 is higher than the depolymerization heating temperature by the heater 320 provided next to the depolymerization reaction tank 300. In the polymerization reaction tank 400, PET having a high molecular weight and a high melting point is produced, but by maintaining the temperature higher than that of the depolymerization reaction tank 300 in which BHET having a low molecular weight and a low melting point is produced, the PET, which is the main product of the polymerization reaction tank 400, is maintained in a molten state. The polymerization reaction of BHET to PET in FIG. 2 is preferably performed in a vacuum state. For this purpose, the polymerization reaction tank 400 is provided with a vacuum pump or the like (not shown).

[0027] Since the viscosity of the fluid in the polymerization reaction tank 400, where PET having a large molecular weight is produced, is higher than the viscosity of the fluid in the depolymerization reaction tank 300, where BHET having a smaller molecular weight than PET, which is a polymer, is produced, a stirring blade 420 for high viscosity is used to stir the fluid in the polymerization reaction tank 400 and promote the polymerization reaction. Examples of the stirring blade 420 for high viscosity include an anchor blade and a helical ribbon blade.

[0028] IV (intrinsic viscosity) value or inherent viscosity is known as a value that correlates with the degree of polymerization of polymers such as PET. The IV value (dL / g) is also used as an index of the use of polymers, and for PET, an IV value of about 0.72 or more can be used for bottles, an IV value of about 0.65 or more can be used for sheets, films, etc., and an IV value of about 0.58 or more can be used for fibers. In this embodiment, the object is to finally obtain PET with an IV value that can be used for bottles and sheets. As described later, the IV value is also increased in the polymerization promoter 500 and / or the polymer supply section 600 downstream of the polymerization reaction tank 400, so the IV value of the PET synthesized in the polymerization reaction tank 400 may be relatively low. Specifically, the IV value of the PET synthesized in the polymerization reaction tank 400 is between 0.2 and 0.7, preferably between 0.3 and 0.7, and more preferably between 0.3 and 0.55.

[0029] A buffer tank 430 may be provided downstream of the polymerization reaction tank 400 to temporarily store the polymer synthesized in the polymerization reaction tank 400 before supplying it to the polymerization accelerator 500 and / or the polymer supply section 600. The buffer tank 430 may be provided with a second preheater 431 to heat or keep the polymer warm before supplying it to the polymerization accelerator 500 and / or the polymer supply section 600. The second preheater 431 may maintain the polymer at a temperature (between 250°C and 300°C) similar to that of the heater 410 provided next to the polymerization reaction tank 400, or may maintain the polymer at a temperature (between 250°C and 290°C) suitable for polymerization reaction similar to that of the heater 520 provided next to the polymerization accelerator 500 described later, or may maintain the polymer at a temperature (between 250°C and 290°C) similar to that of the heater 620 provided next to the polymer supply section 600 described later.

[0030] In this way, by providing the buffer tank 430 equipped with a preheating mechanism (second preheater 431) as necessary in front of the polymerization accelerator 500 and / or the polymer supply section 600, the polymer waiting to be introduced into the polymerization accelerator 500 and / or the polymer supply section 600 can be stored while being kept at an appropriate temperature. As a result, the overall capacity of the chemical recycling apparatus 100 can be increased, and the chemical recycling apparatus 100 can be operated stably and continuously while supplying appropriate amounts of reactants to each processing section such as the depolymerization reaction tank 300, the polymerization reaction tank 400, the polymerization accelerator 500, and the polymer supply section 600 at appropriate times (without causing so-called "resin shortage"). Note that the preheating mechanism such as the second preheater 431 may be provided in any manner at any position between the polymerization reaction tank 400 and the polymerization accelerator 500 and / or at any position between the polymerization accelerator 500 and the polymer supply section 600, without being limited to the buffer tank 430.

[0031] A by-product removal device or polymerization promotion device 500 may be provided downstream of the polymerization reaction tank 400 (and upstream of the polymer supply section 600 described below), through which PET (main product) and EG (by-product) produced by the polymerization reaction in the polymerization reaction tank 400 are passed to remove EG as a by-product. The polymerization promotion device 500 in the illustrated example includes a number of linear members 510 extending downward. Due to the increased surface area provided by the number of linear members 510, volatilization of EG attached to the surface of each linear member 510 is promoted, and EG is effectively separated and removed from the highly viscous PET.

[0032] This EG may be circulated to the depolymerization agent supply section 310 and used for the depolymerization reaction of PET in the depolymerization reaction tank 300. Since the EG separated and removed in the polymerization promotion device 500 can be reused on the spot (in the depolymerization reaction tank 300) without being wasted, the operating efficiency of the chemical recycling apparatus 100 can be improved. In particular, the amount of EG purchased for the depolymerization reaction of PET in the depolymerization reaction tank 300 can be significantly reduced, which leads to a reduction in the operating cost of the chemical recycling apparatus 100.

[0033] Furthermore, PET with a relatively low degree of polymerization (i.e., IV value) and BHET that did not react in the polymerization reaction tank 400 also adhere to the surface of each linear member 510, and the large surface area allows the same polymerization reaction as in the polymerization reaction tank 400 to proceed effectively. Therefore, the IV value of PET as the main product is increased by passing through the polymerization promoter 500. Specifically, the IV value of PET after passing through the polymerization promoter 500 is 0.7 or more, preferably 0.8 or more, and more preferably 0.85 or more.

[0034] In order to promote such a polymerization reaction, the inside of the polymerization promotion device 500 is maintained at a temperature suitable for the polymerization reaction by a heater 520 (FIG. 1) or a warmer as a second heater provided next to the polymerization promotion device 500. Specifically, the heating temperature by the heater 520 is between 250° C. and 290° C., and preferably between 260° C. and 280° C. Here, the heating temperature by the heater 520 provided next to the polymerization promotion device 500 is preferably higher than the polymerization heating temperature by the heater 410 provided next to the polymerization reaction tank 400. Since the polymerization reaction proceeds more in the polymerization promotion device 500 than in the polymerization reaction tank 400, the molecular weight of the PET as a polymer increases and the melting point increases. Therefore, by maintaining the inside of the polymerization promotion device 500 at a higher temperature than in the polymerization reaction tank 400, the PET as a product of the polymerization promotion device 500 can be maintained in a molten state. A heater or a warmer serving as a second heater for heating or warming at least the polymerization heating temperature by the heater 410 provided adjacent to the polymerization reaction tank 400 may be provided around the piping between the polymerization reaction tank 400 and the polymerization accelerator 500. The polymerization reaction in the polymerization accelerator 500 is preferably carried out in a vacuum state, similar to the polymerization reaction in the polymerization reaction tank 400. For this reason, a vacuum pump (not shown) or the like is provided adjacent to the polymerization accelerator 500. By creating a vacuum state (reduced pressure state) inside the polymerization accelerator 500, EG as a by-product can be efficiently removed.

[0035] The configuration of the polymerization promoter 500 is not limited to the "vertical type" as shown in FIG. 1. For example, a "horizontal type" stirring device as shown in FIG. 3 may be used as the polymerization promoter 500. This stirring device has two rotating shafts extending in a direction perpendicular to the paper surface of FIG. 3 and two stirring blade groups that rotate around the two rotating shafts to stir PET and EG as stirring objects. Stirring by the two stirring blade groups promotes volatilization of EG, so that EG is effectively separated and removed from the highly viscous PET. Details of the stirring device in FIG. 3 are disclosed in Japanese Patent No. 2925599, which is incorporated herein by reference. The configuration or function of such a "vertical type" or "horizontal type" polymerization promoter 500 may be realized as a part of the polymer supply section 600 described later. In this case, it is not necessary to provide the polymerization promoter 500 separately from the polymer supply section 600.

[0036] The polymer supplying section 600 supplies a polymer such as PET synthesized in the polymerization reaction tank 400 and / or the polymerization promoting device 500 to the injection molding machine 1 which molds a second molded product such as a PET bottle. The polymer supplying section 600 is equipped with a transfer pump 610 such as a gear pump or a screw pump which is suitable for supplying the PET with high purity and high viscosity (i.e., high polymerization degree or high IV value) from which EG as a by-product has been removed in the polymerization promoting device 500 in a molten state to the injection molding machine 1.

[0037] The polymer supply section 600 is provided with a heater 620 or a warmer as a first heater for heating or warming a polymer such as PET transferred to the injection molding machine 1 by the transfer pump 610 to maintain the polymer in a molten state. Specifically, the heating temperature by the heater 620 is between 250° C. and 290° C., and preferably between 260° C. and 280° C. Here, the heating temperature (first heating temperature) by the heater 620 (first heater) provided in the polymer supply section 600 is preferably higher than a second heating temperature by a second heater such as the heater 410 provided next to the polymerization reaction tank 400, the heater 520 provided next to the polymerization promotion device 500, or a heater (not shown) provided between the polymerization reaction tank 400 and the polymerization promotion device 500. The polymerization reaction started in the polymerization reactor 400 gradually progresses and is completed in the polymerization accelerator 500, so that the molecular weight of the polymer, such as PET, becomes larger in the polymer supply section 600 than in the polymerization reactor 400 and the polymerization accelerator 500, and the melting point becomes higher. Therefore, by making the first heating temperature in the polymer supply section 600 higher than the previous second heating temperature, the polymer, such as PET, having a high viscosity (i.e., high polymerization degree or high IV value) and a high melting point, can be maintained in a molten state. In addition, the polymer supply section 600 may be provided with a vacuum pump or the like (not shown). By making the inside of the polymer supply section 600 a vacuum state (reduced pressure state), the polymerization degree can be increased in the polymer supply section 600 as well.

[0038] A temperature gradient may be provided so that the heating temperature increases stepwise from the polymerization reaction tank 400 to the polymer supply section 600. For example, the heating temperature by a heater (not shown) provided between the polymerization reaction tank 400 and the polymerization promoter 500 is made higher than the heating temperature by the heater 410 provided next to the polymerization reaction tank 400, the heating temperature by the heater 520 provided next to the polymerization promoter 500 is made higher than the heating temperature by the heater (not shown), and the heating temperature by the heater 620 provided in the polymer supply section 600 is made higher than the heating temperature by the heater 520, so that the polymer such as PET, whose melting point increases from the polymerization reaction tank 400 to the polymer supply section 600, can be reliably maintained in a molten state. Note that a heater may be provided between the polymer supply section 600 and the injection molding machine 1 to heat or keep the polymer such as PET warm and maintain it in a molten state.

[0039] The injection molding machine 1 molds a polymer such as PET in a molten state generated in the chemical recycling apparatus 100 into a second molded product. The second molded product may be the same type as or different from the first molded product to be subjected to processing such as crushing in the polymer adjustment apparatus 200. For example, both the first molded product and the second molded product may be PET bottles. Alternatively, one of the first molded product and the second molded product may be a PET bottle, and the other may be a molded product other than a bottle, such as a sheet, film, or fiber. Generally, in mechanical recycling, the IV value of the second molded product after recycling is lower than the IV value of the first molded product and / or solid material before recycling. However, according to the chemical recycling apparatus 100 according to this embodiment, which is equipped with a mechanism for increasing the IV value such as the foreign matter removal device 340, 350, 360 and the polymerization promotion device 500, the IV value of the second molded product after recycling can be made higher than the IV value of the first molded product and / or solid material before recycling. For example, according to this embodiment, low IV PET fibers as the first molded article and / or solid material can be recycled into high IV PET bottles as the second molded article.

[0040] The injection molding machine 1 molds molten resin such as PET into a second molded product. An injection molding machine using molten resin as a raw material is disclosed in, for example, Patent Document 2. This application incorporates by reference the entire contents of that document (Japanese Application No. 2020-130985) filed on July 31, 2020. As shown in FIG. 1, multiple injection molding machines 1 may be provided in parallel. Note that the molding machine to which the molten resin or the like is supplied from the chemical recycling device 100 may be any molding machine (e.g., a compression molding machine) and is not limited to an injection molding machine.

[0041] In the present embodiment as described above, the polymer resynthesized in the polymerization reaction tank 400 is not made into flakes or pellets, but is supplied as is to the injection molding machine 1 by the polymer supply unit 600. Since the conventional cooling and heating processes for flakes and pellets are no longer necessary, molded products such as PET bottles can be recycled with less energy.

[0042] In the chemical recycling apparatus 100 according to this embodiment, the polymer resynthesized in the polymerization reaction tank 400 is directly supplied to the injection molding machine 1, so that it is necessary to quickly realize the IV value of the polymer required for the molded product (second molded product). In this embodiment, a polymerization promoter 500 and / or a polymer supply section 600 having a function of promoting the polymerization reaction and increasing the IV value of the polymer are provided in addition to the polymerization reaction tank 400, so that such a requirement can be fully met.

[0043] FIG. 4 is a schematic diagram showing the configuration of a chemical recycling molding system according to a modified example. The same components as those in FIG. 1 are given the same reference numerals, and duplicated explanations are omitted. In this modified example, a polymer return section 1000 is provided to return at least a part of the polymer synthesized in the polymerization reaction tank 400 to the polymerization reaction tank 400 and / or the depolymerization reaction tank 300. In the illustrated example, the polymer return section 1000 is provided between the by-product removal device 500 and the polymer supply section 600, but is not limited thereto. The polymer return section 1000 may be provided at any position between the by-product removal device 500 and the injection molding machine 1. The polymer return section 1000 may be provided, for example, between the polymer supply section 600 and the injection molding machine 1.

[0044] The polymer return section 1000 returns at least a portion of the polymer synthesized in the polymerization reaction tank 400 (in the illustrated example, the polymer from which by-products have been further removed by the by-product removal device 500) to the polymerization reaction tank 400 and / or the depolymerization reaction tank 300 instead of sending it to the polymer supply section 600. For example, the polymer return section 1000 may supply the polymer to a buffer tank 370 provided upstream of the polymerization reaction tank 400 in order to return the polymer to the polymerization reaction tank 400, or may supply the polymer to a polymer adjustment device 200 provided upstream of the depolymerization reaction tank 300 in order to return the polymer to the depolymerization reaction tank 300.

[0045] The main purpose of the polymer return section 1000 is to deal with the mismatch in operating time and capacity between the chemical recycling apparatus 100 and the injection molding machine 1. For example, since the chemical recycling apparatus 100 typically operates continuously (continuous operation) and the injection molding machine 1 typically operates intermittently (intermittent operation), the injection molding machine 1 cannot accept the entire amount of polymer from the polymer supply section 600 (unacceptable period), particularly while the injection molding machine 1 is stopped for maintenance of a mold or the like. Even during such an unacceptable period, the excess polymer that cannot be accepted by the injection molding machine 1 is returned in a molten state to the polymerization reaction tank 400 and / or the depolymerization reaction tank 300 so that the chemical recycling apparatus 100 can continue to operate continuously without wasting the excess polymer. In this way, it is no longer necessary to turn the excess polymer in a molten state that cannot be accepted by the injection molding machine 1 into flakes or pellets by cooling or heat dissipation, thereby reducing energy waste.

[0046] The polymer return section 1000 may change the return destination (polymerization reaction tank 400 and / or depolymerization reaction tank 300) or the return ratio of the excess polymer depending on the length of the unacceptable period. For example, before the unacceptable period exceeds a predetermined period threshold, more polymer than the depolymerization reaction tank 300 may be returned to the polymerization reaction tank 400, and after the unacceptable period exceeds the period threshold, more polymer than the polymerization reaction tank 400 may be returned to the depolymerization reaction tank 300.

[0047] If the unacceptable period is short and does not exceed the period threshold, it is believed that the polymer will not deteriorate or the IV value will not increase excessively even if the molten polymer is circulated through the polymerization reaction tank 400 (and the by-product removal device 500) at a high temperature (for example, between 270°C and 280°C as described above). For this reason, it is preferable for the polymer return section 1000 to return most of the excess polymer (for example, 100%, 80%, 60%) to the polymerization reaction tank 400 (buffer tank 370) during a short unacceptable period.

[0048] On the other hand, if the unacceptable period exceeds the period threshold and becomes long, the polymer may deteriorate or the IV value may increase excessively due to the thermal history caused by the molten polymer circulating through the polymerization reactor 400 (and the by-product removal device 500) at a high temperature (for example, between 270°C and 280°C as described above). Therefore, for a long unacceptable period, it is preferable that the polymer return section 1000 returns most of the excess polymer (for example, 100%, 80%, or 60%) to the depolymerization reactor 300 (polymer adjustment device 200). Since the thermal history is substantially reset by the second depolymerization reaction in the depolymerization reactor 300, the deterioration of the polymer supplied to the injection molding machine 1 by the polymer supply section 600 after the unacceptable period and the excessive increase in the IV value are effectively prevented.

[0049] In this modification, since the temperature of the circulating molten polymer is substantially constant (for example, between 270°C and 280°C as described above), the length of the unacceptable period represents the thermal history. On the other hand, when the temperature of the circulating molten polymer can change significantly, the thermal history may be accurately grasped by monitoring the temperature in addition to the length of the unacceptable period. In this case, the polymer return section 1000 may return more polymer to the polymerization reaction tank 400 than the depolymerization reaction tank 300 before the thermal history exceeds a predetermined thermal history threshold, and may return more polymer to the depolymerization reaction tank 300 than the polymerization reaction tank 400 after the thermal history exceeds the thermal history threshold.

[0050] The polymer return section 1000 may change the return destination (polymerization reaction tank 400 and / or depolymerization reaction tank 300) and the return ratio depending on the physical property values ​​such as the IV value of the polymer to be returned. For example, when the IV value is within a predetermined allowable range, more polymer than the depolymerization reaction tank 300 may be returned to the polymerization reaction tank 400, and when the IV value is outside the allowable range (specifically, when it is greater than the upper limit of the allowable range), more polymer than the polymerization reaction tank 400 may be returned to the depolymerization reaction tank 300. In the latter case, the excessively increased IV value is reduced to within the allowable range by a second depolymerization reaction in the depolymerization reaction tank 300.

[0051] Furthermore, the polymer return section 1000 may gradually change the ratio of the polymer returned to the polymerization reaction tank 400 and the depolymerization reaction tank 300 depending on the length of the unacceptable period and physical properties such as the IV value of the polymer to be returned. For example, the ratio of the polymer returned to the depolymerization reaction tank 300 may be gradually increased as the unacceptable period becomes longer, or the ratio of the polymer returned to the depolymerization reaction tank 300 may be gradually increased as the IV value increases.

[0052] Fig. 5 is a schematic diagram showing a second embodiment of the recycle system according to the present disclosure. The same components as those in the first embodiment in Fig. 1 are given the same reference numerals and the description thereof will be omitted. In Fig. 5 and the following similar figures, the components of the recycle system are shown as functional blocks for the sake of convenience.

[0053] The recycling system according to the second embodiment includes a quality determination unit 710, a material sorting unit 720, a chemical recycling apparatus 100, and a mechanical recycling apparatus 900. The chemical recycling apparatus 100 is configured similarly to the first embodiment in Fig. 1, but the polymer adjustment apparatus 200 is omitted in Fig. 5. In the example of Fig. 5, instead of or in addition to the polymer adjustment apparatus 200, the quality determination unit 710 and the material sorting unit 720 are provided.

[0054] The mechanical recycling apparatus 900 performs mechanical recycling processing on solid materials such as PET flakes (specifically, high-quality materials described later). The mechanical recycling apparatus 900 may be configured as a separate apparatus completely independent of the chemical recycling apparatus 100, but in the example of FIG. 5, the polymerization promoter 500 and / or the polymer supply section 600 at the final stage of the chemical recycling apparatus 100 are also used in the mechanical recycling apparatus 900. In such a mechanical recycling apparatus 900, the solid materials (high-quality materials) such as PET flakes are heated and melted by the heater 910, and a polymer such as PET having a desired degree of polymerization or IV value is obtained by a polymerization reaction or the like in the polymerization promoter 500 and / or the polymer supply section 600.

[0055] The heater 910 of the mechanical recycling apparatus 900 may be configured similarly to the buffer tank 430 and the second preheater 431 of the chemical recycling apparatus 100. That is, like the second preheater 431, the heater 910 heats and melts the high-quality material including a polymer such as PET before being supplied to the downstream polymerization promotion apparatus 500 and / or the polymer supply section 600. The heater 910 may heat the high-quality material to a temperature (between 250°C and 300°C) similar to that of the heater 410 provided in the polymerization reaction tank 400 in the chemical recycling apparatus 100, may heat the high-quality material to a temperature (between 250°C and 290°C) suitable for polymerization reaction similar to that of the heater 520 provided in the polymerization promotion apparatus 500, or may heat the high-quality material to a temperature (between 250°C and 290°C) similar to that of the heater 620 provided in the polymer supply section 600. Furthermore, similar to the buffer tank 430, the heater 910 may temporarily store the heated and melted high-quality material such as PET before supplying it to the polymerization promoter 500 and / or polymer supply section 600 in the downstream.

[0056] In this way, by providing the heater 910 having a heating function and a storage function upstream of the polymerization promotion device 500 and / or the polymer supplying section 600, the polymer (such as PET derived from high-quality materials) waiting to be fed into the polymerization promotion device 500 and / or the polymer supplying section 600 can be stored while being kept at an appropriate temperature. As a result, the capacity of the mechanical recycling device 900 or the entire recycling system can be increased, and the mechanical recycling device 900 or the entire recycling system can be operated stably and continuously.

[0057] In the example of Figure 5, where the polymer supply section 600 is shared by the mechanical recycling device 900 and the chemical recycling device 100, PET etc. derived from high-quality materials that have been subjected to mechanical recycling processing in the mechanical recycling device 900 and PET etc. derived from low-quality materials that have been subjected to chemical recycling processing in the chemical recycling device 100 are supplied in a mixed state to the injection molding machine 1.

[0058] The quality determination unit 710 determines the quality of solid materials such as PET flakes based on a predetermined quality determination standard. The material sorting unit 720 sorts solid materials such as PET flakes into high-quality materials determined by the quality determination unit 710 to have a higher quality than the quality determination standard, and low-quality materials determined by the quality determination unit 710 to have a lower quality than the quality determination standard. The quality determination unit 710 and the material sorting unit 720 may be configured as separate entities, but are preferably configured substantially integrally as illustrated in FIG. 6.

[0059] In FIG. 6, PET flakes as solid materials are fed from a supply port at the top left. The PET flakes may include high-quality materials (schematically indicated by a solid circle) whose quality is higher than the quality judgment standard in the quality judgment unit 710, and low-quality materials (schematically indicated by a dashed circle) whose quality is lower than the quality judgment standard. For example, if the PET flakes are derived from a PET bottle, the PET flakes near the outer peripheral surface of the PET bottle may have deteriorated due to the influence of external light or water, and the PET flakes near the inner peripheral surface of the PET bottle may have adsorbed limonene, etc., contained in the contents. These PET flakes may be classified as low-quality materials. On the other hand, PET flakes that are away from the outer peripheral surface and the inner peripheral surface of the PET bottle, or PET flakes that are not deteriorated or contaminated on the outer peripheral surface and the inner peripheral surface, may be classified as high-quality materials.

[0060] In this way, solid materials such as PET flakes, which are a mixture of low-quality material and high-quality material, are conveyed from one end (the left end in FIG. 6) of the belt conveyor 721 to the other end (the right end in FIG. 6) and fall. The sensor 711 measures each PET flake that has fallen from the other end of the belt conveyor 721 in a non-contact manner. Any method of non-contact measurement may be used, and electricity, magnetism, heat, etc. may be used, but light and / or electromagnetic waves are preferably used. In this case, the sensor 711 optically measures each PET flake that has fallen from the other end of the belt conveyor 721. Specifically, the sensor 711 acquires light from each PET flake or an image of each PET flake. The sensor 711 may measure natural light or ambient light reflected by each PET flake, or may measure measurement light of any wavelength emitted by the sensor 711 itself and reflected by each PET flake.

[0061] Among the PET flakes continuously measured by the sensor 711, various characteristics of the low-quality material, such as optical characteristics (e.g., color), change with deterioration of quality, so that a significant difference occurs in the measurement value by the sensor 711 between the low-quality material and the high-quality material. Therefore, the quality determination unit 710 can distinguish the PET flakes into high-quality material and low-quality material by applying an appropriate quality determination standard or quality determination threshold value to the measurement value by the sensor 711. Then, the material sorting unit 720 sorts the PET flakes into high-quality material and low-quality material according to the determination result by the quality determination unit 710. In the example of FIG. 6, the material sorting unit 720, which is realized by an air nozzle, sprays air only on the PET flakes determined to be low-quality material by the quality determination unit 710 (conversely, air may be sprayed only on the PET flakes determined to be high-quality material by the quality determination unit 710), thereby sorting or separating the high-quality material from the high-quality material.

[0062] As described above, the PET flakes supplied to the recycling system shown in FIG. 5 are separated into high-quality materials and low-quality materials in a solid state by the action of the quality determination unit 710 and the material sorting unit 720. As shown in FIG. 5, the high-quality materials in a solid state sorted by the material sorting unit 720 are supplied to the mechanical recycling device 900 and subjected to a mechanical recycling process. The low-quality materials in a solid state sorted by the material sorting unit 720 are supplied to the chemical recycling device 100 and subjected to a chemical recycling process. The high-quality materials and / or low-quality materials sorted by the material sorting unit 720 may be directly input to the mechanical recycling device 900 and / or the chemical recycling device 100, or may be temporarily stored before being input to the mechanical recycling device 900 and / or the chemical recycling device 100.

[0063] In this embodiment, solid materials such as PET flakes are sorted into high-quality materials and low-quality materials based on quality criteria. High-quality materials are efficiently recycled by mechanical recycling processing (mechanical recycling device 900), which has a low quality improvement effect but requires simple equipment, and low-quality materials are recycled while their quality is improved by chemical recycling processing (chemical recycling device 100), which has a high quality improvement effect. Thus, according to this embodiment, the quality of the recycled products can be stabilized by applying an appropriate recycling processing (mechanical recycling processing or chemical recycling processing) according to the quality of the solid materials such as PET flakes.

[0064] Also, according to this embodiment, the high-quality materials selected by the material sorting unit 720 are sorted to the mechanical recycling apparatus 900, so the burden on the chemical recycling apparatus 100 can be reduced. This allows the scale of the chemical recycling apparatus 100, which is generally more complicated and expensive than the mechanical recycling apparatus 900, to be reduced. Furthermore, the high-quality materials selected by the material sorting unit 720 are quickly and efficiently recycled by the mechanical recycling apparatus 900, which has a simpler configuration and lower operating costs than the chemical recycling apparatus 100, so the throughput and efficiency of the entire recycling system can be dramatically improved.

[0065] In addition, the recycling system according to this embodiment includes both the mechanical recycling device 900 for high-quality materials and the chemical recycling device 100 for low-quality materials, so that it can also accept fixed materials such as PET flakes of unstable quality. In this way, according to this embodiment, a highly versatile recycling system capable of handling a wide range of fixed materials can be provided.

[0066] FIG. 7 is a schematic diagram of a third embodiment of the recycling system according to the present disclosure. The same components as those in the above-mentioned embodiments are given the same reference numerals, and the description of the same purpose is omitted. The recycling system according to the third embodiment includes a partial depolymerization section 730, a solid-liquid separation section 740, a degraded material recovery section 750, and a chemical recycling apparatus 100. The chemical recycling apparatus 100 is configured similarly to the first embodiment in FIG. 1, but the polymer adjustment apparatus 200 is omitted in FIG. 7. In the example of FIG. 7, instead of or in addition to the polymer adjustment apparatus 200, a partial depolymerization section 730, a solid-liquid separation section 740, and a degraded material recovery section 750 are provided.

[0067] The partial decomposition polymerization section 730 partially decomposes solid materials such as PET flakes into depolymerized polymers by a depolymerization reaction. When the polymer to be recycled contained in the solid material is PET, PET is decomposed by EG as a depolymerization agent according to the depolymerization reaction (300) shown in FIG. 2, and BHET is obtained as a depolymerized polymer. This depolymerization reaction is substantially the same as that occurring in the depolymerization reaction tank 300 in the chemical recycling device 100, but in the partial decomposition polymerization section 730, only the surface portion of the solid material such as PET flakes is decomposed by the depolymerization reaction. As described above, for example, the quality of the surface of PET flakes derived from PET bottles may be deteriorated due to the influence of light and water from the outside of the PET bottle, or the adsorption of limonene contained in the contents of the PET bottle. The main purpose of the partial decomposition polymerization section 730 is to decompose the surface portion of the solid material such as PET flakes, the quality of which may be deteriorated in this way, by a depolymerization reaction.

[0068] The solid-liquid separation section 740 separates the solid and liquid components obtained in the partial depolymerization section 730. When the solid material is PET flakes, the solid components include high-quality PET flakes or high-quality PET particles that remain in the partial depolymerization section 730 without being decomposed into liquid BHET, and the liquid components are a mixture of BHET generated by decomposition of the surface parts of the PET flakes through a depolymerization reaction, fine particles on the surface parts of the deteriorated PET flakes, unreacted EG, contaminants related to the quality deterioration of the surface parts of the PET flakes, cleaning liquids such as water, etc. The solid components, which are high-quality solid materials, are supplied to the chemical recycling device 100 and subjected to chemical recycling processing. The liquid components that are not suitable for recycling processing and may also contain contaminants are collected in the deteriorated material collection section 750.

[0069] It is not necessary for the solid-liquid separation section 740 according to this embodiment to completely separate solids and liquids. For example, in the solid-liquid separation section 740 specifically illustrated in FIG. 8 to FIG. 11 described later, high-quality PET flakes or high-quality PET particles, which are solids, are taken out from the solid-fraction take-out section 850 at the bottom in a state of slurry or the like mixed with liquid. In this way, the solid fraction separated by the solid-liquid separation section 740 may contain any form of solid, such as high-quality PET flakes or high-quality PET particles, and may contain a liquid that forms a slurry or the like together with the solid. In other words, the solid fraction in this embodiment may contain any form of solid (typically, solid particles) derived from a solid material, regardless of the presence or absence of liquid.

[0070] In this embodiment, the surfaces of solid materials such as PET flakes, which are prone to quality deterioration, are partially decomposed, and solids of relatively high quality are separated. By subjecting the high-quality solids to chemical recycling treatment in this way, the quality of the recycled products can be stabilized.

[0071] In addition, the recycling system according to this embodiment can accept low-quality fixed materials such as PET flakes because the surface parts that are prone to quality deterioration can be effectively removed by the action of the partial depolymerization section 730 and the solid-liquid separation section 740. In this way, according to this embodiment, a highly versatile recycling system that can handle a wide range of fixed materials can be provided.

[0072] Although the partial depolymerization section 730 and the solid-liquid separation section 740 may be configured as separate bodies, it is preferable that they are configured substantially integrally as illustrated in Fig. 8. In Fig. 8, the partial depolymerization section 730 and the solid-liquid separation section 740 are configured by a partial depolymerization reaction tank 810, a solid material supply section 820, a depolymerization agent supply section 830, a depolymerization discharge section 840, and a solid fraction removal section 850.

[0073] In the partial depolymerization reaction tank 810, a partial depolymerization reaction of solid materials such as PET flakes occurs, as described above with respect to the partial depolymerization section 730. The solid material supply section 820 supplies solid materials such as PET flakes into the partial depolymerization reaction tank 810. The depolymerization agent supply section 830 supplies a depolymerization agent such as EG that decomposes polymers such as PET into the partial depolymerization reaction tank 810. As described later, the depolymerization agent supply section 830 may supply a cleaning liquid for cleaning solids (such as high-quality PET) remaining after the depolymerization reaction into the partial depolymerization reaction tank 810. The depolymerization discharge section 840 discharges liquid depolymerized polymers such as BHET generated by the depolymerization reaction. As described later, the depolymerization discharge section 840 is not limited to depolymerized polymers such as BHET, and may discharge any liquid in the partial depolymerization reaction tank 810, and may discharge the above-mentioned cleaning liquid, for example. The solid fraction removal section 850 removes solids (such as high-quality PET) remaining after the depolymerization reaction.

[0074] The configuration of FIG. 8 realizes the functions of the partial depolymerization section 730 and the solid-liquid separation section 740, for example, by the following procedure. First, in a first step, the solid material supply section 820 supplies a solid material such as PET flakes into the partial depolymerization reaction tank 810, and the depolymerization agent supply section 830 supplies a depolymerization agent such as EG into the partial depolymerization reaction tank 810. At this time, the inside of the partial depolymerization reaction tank 810 is maintained at the same temperature (e.g., between 220° C. and 250° C., preferably between 230° C. and 245° C., more preferably between 235° C. and 240° C.) and pressure (e.g., between 0.3 MPa and 0.8 MPa, preferably between 0.4 MPa and 0.6 MPa, more preferably between 0.45 MPa and 0.55 MPa) as those in the above-mentioned depolymerization reaction tank 300. Therefore, in the partial depolymerization reaction tank 810, substantially the same depolymerization reaction as that occurring in the depolymerization reaction tank 300 occurs on the surface portion of the solid material such as PET flakes supplied by the solid material supply unit 820.

[0075] The depolymerization agent supplying unit 830 may supply the depolymerization agent such as EG in a liquid state (e.g., an aqueous solution) into the partial depolymerization reaction tank 810, but it is preferable to supply the vapor of the depolymerization agent such as EG into the partial depolymerization reaction tank 810. For example, as shown in FIG. 8, the depolymerization agent supplying unit 830 provided on the ceiling of the partial depolymerization reaction tank 810 may inject or spray the vapor of EG into the partial depolymerization reaction tank 810. Advantages of supplying the depolymerization agent such as EG as vapor include the following: since the influence of the phase change across the boiling point can be reduced, the depolymerization reaction can proceed stably and quickly in a high-temperature environment; since the reaction temperature can be increased, the need for a catalyst other than EG can be reduced; and in extreme cases, the surface depolymerization reaction can be caused without a catalyst.

[0076] After the depolymerization reaction of the surface portion of the solid material such as PET flakes has sufficiently progressed in the partial depolymerization reaction tank 810 (i.e., after the first step), or while the depolymerization reaction is progressing (i.e., simultaneously with the first step), as a second step, liquid contents including depolymerized materials such as BHET generated by the depolymerization reaction, fine particles on the surface portion of the solid material such as deteriorated PET flakes, depolymerization materials such as unreacted EG, contaminants related to the quality deterioration of the surface portion of the solid material such as PET flakes, etc. are discharged from a depolymerization discharge part 840 provided at the bottom of the partial depolymerization reaction tank 810. The depolymerization discharge part 840 is composed of a strainer and a valve capable of discharging the liquid contents constantly or intermittently.

[0077] After the depolymerization reaction of the surface portion of the solid material such as PET flakes has sufficiently progressed in the partial depolymerization reaction tank 810, as a third step following the first step, a depolymerization agent supplying section 830 provided on the ceiling of the partial depolymerization reaction tank 810 may supply a cleaning liquid into the partial depolymerization reaction tank 810 to clean the solid portion (such as high-quality PET flakes from which deteriorated surface portions have been removed) remaining after the depolymerization reaction. Examples of the cleaning liquid include water and liquid EG (e.g., an aqueous solution) that is also used as a depolymerization agent. In this case, as a fourth step following the third step, a depolymerization discharge section 840 provided on the bottom of the partial depolymerization reaction tank 810 discharges the cleaning liquid. Here, the second step and the fourth step of discharging the liquid from the depolymerization discharge section 840 may be performed simultaneously.

[0078] After the above first to fourth steps are completed, high-quality PET flakes and the like, from which the deteriorated surface portions have been removed in the first and second steps and which have been washed in the third and fourth steps, are deposited and remain as solid matter at the bottom of the partial decomposition polymerization reaction tank 810. In the final fifth step, the solid matter including such high-quality PET flakes and the like is taken out from a solid matter take-out section 850 provided at the bottom of the partial decomposition polymerization reaction tank 810.

[0079] The first to fifth steps as described above may be repeated for each processing unit or batch of solid material to be processed by partial depolymerization (or surface depolymerization) by the partial depolymerization section 730 and solid-liquid separation by the solid-liquid separation section 740, which are executed by these steps. In addition, by providing a plurality of processing devices as shown in Fig. 8, even a large amount of solid material may be processed in parallel at high speed.

[0080] Alternatively, instead of providing a dedicated treatment device as shown in Fig. 8, the depolymerization reaction tank 300, which is also used to cause the depolymerization reaction, may function as the partial depolymerization section 730 and the solid-liquid separation section 740. For example, when PET flakes are first supplied, the depolymerization reaction tank 300 functions as the partial depolymerization section 730 and the solid-liquid separation section 740, and extracts solids consisting of high-quality PET flakes through a surface depolymerization reaction (the liquids are separated and recovered in the deteriorated material recovery section 750). Then, the depolymerization reaction tank 300 functions as the original depolymerization reaction tank 300, and decomposes the entire amount of the solids (high-quality PET flakes) into BHET as a depolymer by the depolymerization reaction.

[0081] Figures 9 to 11 show schematic diagrams of modified examples of the processing apparatus shown in Figure 8. The same components in Figures 8 to 11 are given the same reference numerals and the description thereof will be omitted.

[0082] In the modified example of FIG. 9 , the partial depolymerization section 730 and the solid-liquid separation section 740 are composed of a partial depolymerization reaction tank 810, a solid material supply section 820, a depolymerization agent supply section 830, a depolymerization discharge section 840, a solid fraction removal section 850, and a partition 860.

[0083] The depolymerization agent supplying section 830, which supplies a depolymerization agent such as EG and / or a cleaning solution into the partial depolymerization reaction tank 810, is provided at any location (including, for example, the side or bottom) on the inner wall surface of the partial depolymerization reaction tank 810, not limited to the ceiling part as shown in FIG. 8. A partition 860, which divides the inside of the partial depolymerization reaction tank 810 into upper and lower parts, has holes through which at least a part of solid material such as PET flakes before the depolymerization reaction cannot pass. Such a partition 860 is composed of, for example, a mesh made of a metal such as stainless steel, or a net or plate having holes smaller than those of general PET flakes. At least one of the solid material supplying section 820 and the depolymerization agent supplying section 830 may be provided above the partition 860, and at least one of the depolymerization agent supplying section 830, the depolymerization discharge section 840, and the solid fraction removal section 850 may be provided below the partition 860.

[0084] As shown in FIG. 9, PET flakes before the depolymerization reaction are collected on a partition 860. Then, a plurality of depolymerization agent supplying units 830 spray depolymerization agents such as EG from various directions onto the PET flakes thus collected on the partition 860, so that the surface portions of the PET flakes are efficiently decomposed by the depolymerization reaction. Liquid depolymerized polymers such as BHET generated by the depolymerization reaction pass downward through the holes of the partition 860 and are discharged from the depolymerization discharge unit 840. Furthermore, the cleaning liquid supplied from at least one of the plurality of depolymerization agent supplying units 830 also passes downward through the holes of the partition 860 and is discharged from the depolymerization discharge unit 840. In addition, solids such as high-quality PET flakes that have become smaller due to the depolymerization reaction of the surface portions pass downward through the holes of the partition 860 and are taken out from the solids take-out unit 850.

[0085] In the modified example of FIG. 10 , the partial depolymerization section 730 and the solid-liquid separation section 740 are composed of a partial depolymerization reaction tank 810, a solid material supply section 820, a depolymerization agent supply section 830, a depolymerization discharge section 840, a solid fraction removal section 850, and an agitator 870.

[0086] In this modification, the depolymerization agent supply unit 830 is provided at the bottom of the partial depolymerization reaction tank 810, and the depolymerization discharge unit 840 is provided at the top of the partial depolymerization reaction tank 810 (or above the solid fraction removal unit 850). The liquid depolymerization agent such as EG, the catalyst, and / or the liquid depolymerized material such as BHET produced by the depolymerization reaction supplied from the depolymerization agent supply unit 830 fill the partial depolymerization reaction tank 810 from the bottom to the position where the depolymerization discharge unit 840 is provided. In this manner, the liquid level in the partial depolymerization reaction tank 810 is formed at the position where the depolymerization discharge unit 840 is provided. Excess liquid is discharged from the depolymerization discharge unit 840 constituted by a strainer or a valve. Note that multiple depolymerization discharge units 840 may be provided at different heights. In this case, the depolymerization discharge section 840 provided at the highest position has the function of preventing overflow and forming a liquid level in the partial depolymerization reaction tank 810, and the depolymerization discharge section 840 provided at a lower position discharges depolymerization products such as BHET from an intermediate height position.

[0087] The stirring blade 870 particularly stirs solid materials such as PET flakes and depolymerization agents such as EG as reactants during the depolymerization reaction. This stirring not only efficiently advances the depolymerization reaction, but also breaks down the solid matter (such as high-quality PET) remaining after the depolymerization reaction of the surface portion. The broken down solid matter can pass through the solid matter removal section 850, which is composed of a strainer and a valve, and is removed from the partial depolymerization reaction tank 810.

[0088] The above-mentioned series of processes may be performed as a batch process similar to that shown in Fig. 8 or 9, or may be performed as a continuous process. In the continuous process, while the stirring blade 870 is continuously rotating in the partial depolymerization reaction tank 810, at least one of the supply of solid material from the solid material supply unit 820, the supply of a depolymerization agent from the depolymerization agent supply unit 830, the discharge of depolymerization from the depolymerization agent discharge unit 840, and the removal of solid matter from the solid matter removal unit 850 is performed continuously or intermittently.

[0089] In the modified example of FIG. 11 , the partial depolymerization section 730 and the solid-liquid separation section 740 are composed of a partial depolymerization reaction tank 810, a solid material supply section 820, a depolymerization agent supply section 830, a depolymerization discharge section 840, a solid fraction removal section 850, a stirring blade 870, and a baffle 880.

[0090] In this modified example, the solid matter (such as high-quality PET) remaining after the depolymerization reaction of the surface portion of a solid material such as PET flakes is efficiently broken down into fine particles by colliding with a baffle 880, also known as a baffle plate, as it is stirred by the stirring blade 870.

[0091] Fig. 12 shows a schematic configuration of a recycle system according to a modification of Fig. 7. The same components as those in Fig. 7 are given the same reference numerals and redundant explanations will be omitted. In this modification, the partial depolymerization section 730 is provided with a mechanical mixer 760 that mechanically or physically mixes the depolymerization agent and the polymer at least in the early stage of the depolymerization reaction in which the polymer is decomposed into depolymers by the depolymerization agent.

[0092] As shown in Figure 2, the depolymerization reaction in which a depolymerization agent such as EG decomposes polymers such as PET into depolymerized polymers such as BHET is essentially a chemical process. However, as shown diagrammatically in Figure 13, in the early or protostage of the depolymerization reaction when the degree of polymerization of the polymer is high, polymers such as PET may exist in large chunks such as flakes or pellets, and mechanical actions such as stirring and mixing are dominant over chemical actions (chemical reactions). On the other hand, in the later stages of the depolymerization reaction, the intended chemical actions (chemical reactions) become dominant.

[0093] The mechanical mixer 760 according to this modification example efficiently advances the period by mechanically mixing the depolymerization agent such as EG and the polymer such as PET, particularly in the early or former period of the depolymerization reaction in which mechanical action is dominant, and enables a rapid transition to the later period in which the desired chemical action (chemical reaction) is dominant (mainly proceeding in the depolymerization reaction tank 300 subsequent to the partial depolymerization unit 730). As a result, the depolymerization reaction in the partial depolymerization unit 730 and the depolymerization reaction tank 300 can be efficiently advanced in a short time. The mechanical mixer 760 may continue to mechanically mix the depolymerization agent such as EG and the polymer such as PET not only in the early or former period of the depolymerization reaction in which mechanical action is dominant, but also in the later period of the depolymerization reaction in which chemical action (chemical reaction) is dominant (when proceeding in the partial depolymerization unit 730). The mechanical mixer 760 may be responsible for processes such as pulverization, heating and melting, and mixing, similar to the polymer adjustment device 200 described above. Therefore, the polymer conditioning device 200 may not be provided, or the polymer conditioning device 200 may be integrated into the mechanical mixing section 760 .

[0094] The mechanical mixer 760 as described above may be provided in conjunction with or externally attached to the partial depolymerization section 730 (and solid-liquid separation section 740) having a one-tank configuration as shown in Figures 8 to 11. For example, an ultrasonic device as the mechanical mixer 760, which will be described later, may be attached to the outer wall surface and / or inner wall surface of the partial depolymerization section 730, or a cavitation device as the mechanical mixer 760, which will be described later, may be provided in the upstream of the partial depolymerization section 730.

[0095] The mechanical mixer 760 as described above may be configured in any manner as long as it can achieve the function of mechanically mixing the depolymerization agent such as EG and the polymer such as PET, particularly in the early stage of the depolymerization reaction. In the following, using the partial depolymerization unit 730 and the solid-liquid separation unit 740 shown in Fig. 10 as examples, several non-limiting examples of the mechanical mixer 760 that may be provided therein will be listed.

[0096] Fig. 14 is a schematic diagram of a first embodiment of the mechanical mixer 760. In this embodiment, an ultrasonic device 761 as the first embodiment of the mechanical mixer 760 is additionally provided in the partial depolymerization section 730 and the solid-liquid separation section 740 shown in Fig. 10.

[0097] In the partial depolymerization reaction tank 810, a partial depolymerization reaction of polymers such as PET flakes is carried out, particularly mechanical mixing with a depolymerization agent such as EG in the initial or former stage described above with reference to FIG. 13. The polymer supply unit 820 supplies polymers such as PET flakes into the partial depolymerization reaction tank 810. The depolymerization agent supply unit 830 provided at the bottom of the partial depolymerization reaction tank 810 supplies a depolymerization agent such as EG that decomposes polymers such as PET into the partial depolymerization reaction tank 810. The depolymerization discharge unit 840 provided at the top of the partial depolymerization reaction tank 810 discharges liquid depolymerized polymers such as BHET produced by the depolymerization reaction. The polymer removal unit 850 removes PET slurry and the like remaining after the depolymerization reaction. The PET slurry and the like removed from the polymer removal unit 850 is sent to the subsequent depolymerization reaction tank 300, where it is decomposed into depolymerized polymers such as BHET through further depolymerization reaction (particularly the desired chemical reaction in the latter stage described above with reference to FIG. 13).

[0098] The stirring blade 870 and / or ultrasonic device 761 mechanically mix or stir the polymer such as PET supplied from the polymer supply unit 820 and the depolymerization agent such as EG supplied from the depolymerization agent supply unit 830 in the partial depolymerization reaction tank 810, thereby promoting mechanical mixing in the initial or early stage of the depolymerization reaction carried out by the partial depolymerization unit 730. Such mechanical mixing not only efficiently advances the depolymerization reaction, but also finely disintegrates the PET flakes and the like into a slurry. The finely disintegrated PET slurry can pass through the polymer removal unit 850 composed of a strainer and a valve, and is removed from the partial depolymerization reaction tank 810 and sent to the depolymerization reaction tank 300.

[0099] The ultrasonic device 761 is attached, for example, continuously (for example, annularly) or intermittently to any position on the outer wall surface and / or inner wall surface of the partial decomposition polymerization reaction tank 810. Ultrasonic waves (vibrations) generated by the ultrasonic device 761 mechanically mix the polymer such as PET and the depolymerization agent such as EG in the partial decomposition polymerization reaction tank 810. If it is difficult to attach the ultrasonic device 761 to the wall surface of the partial decomposition polymerization reaction tank 810, another ultrasonic tank incorporating the ultrasonic device 761 may be connected to the partial decomposition polymerization reaction tank 810. In this case, the mechanical mixing by the ultrasonic device 761 is performed in the ultrasonic tank, and the finely divided PET, etc. is taken out from the polymer take-out part 850 of the partial decomposition polymerization reaction tank 810.

[0100] 14, ultrasonic waves generated by ultrasonic device 761 mechanically mix polymers such as PET flakes supplied by polymer supply unit 820 with a depolymerization agent such as EG supplied by depolymerization agent supply unit 830. When PET flakes are too large, it is difficult to mix them with contact-type mixing blade 870, but non-contact ultrasonic device 761 can effectively mix PET flakes regardless of their size.

[0101] After mechanical mixing of polymers such as PET flakes has progressed sufficiently in the partial depolymerization reaction tank 810, or while the mechanical mixing is progressing, a depolymerization liquid containing depolymerized polymers such as BHET generated by the depolymerization reaction is discharged from a depolymerization discharge part 840 provided at the top of the partial depolymerization reaction tank 810. The depolymerization discharge part 840 is configured with a strainer or a valve capable of constantly or intermittently discharging liquid. The liquid depolymerization agent such as EG or a catalyst and / or liquid depolymerized polymers such as BHET generated by the depolymerization reaction supplied from the depolymerization agent supply part 830 fills the partial depolymerization reaction tank 810 from the bottom to the position where the depolymerization discharge part 840 is provided. In this way, a liquid level in the partial depolymerization reaction tank 810 is formed at the position where the depolymerization discharge part 840 is provided. Excess liquid is discharged from a depolymerization discharge part 840 configured with a strainer or a valve. Note that multiple depolymerization discharge parts 840 may be provided at different heights. In this case, the depolymerization discharge section 840 provided at the highest position has the function of preventing overflow and forming a liquid level in the partial depolymerization reaction tank 810, and the depolymerization discharge section 840 provided at a lower position discharges depolymerization products such as BHET from an intermediate height position.

[0102] After sufficient mechanical mixing of polymers such as PET flakes and depolymerization agents such as EG has progressed in the partial depolymerization reaction tank 810, the finely divided and accumulated PET slurry is taken out from the polymer removal section 850 provided at the bottom of the partial depolymerization reaction tank 810.

[0103] Each of the steps described above may be performed continuously by continuing the supply of polymers such as PET flakes by the polymer supply unit 820 and the supply of a depolymerization agent such as EG by the depolymerization agent supply unit 830 (continuous processing), or may be performed for each predetermined processing unit or batch of polymers such as PET flakes and a depolymerization agent such as EG (batch processing). For example, in the continuous processing, while the ultrasonic device 761 is continuously emitting ultrasonic waves and / or the stirring blade 870 is continuously rotating in the partial depolymerization reaction tank 810, at least one of the supply of polymers (PET flakes, etc.) from the polymer supply unit 820, the supply of the depolymerization agent from the depolymerization agent supply unit 830, the discharge of depolymers from the depolymerization discharge unit 840, and the take-out of polymers (PET slurry, etc.) from the polymer take-out unit 850 is performed continuously or intermittently.

[0104] Fig. 15 is a schematic diagram of a second embodiment of the mechanical mixer 760. In this embodiment, a cavitation device 762 as the second embodiment of the mechanical mixer 760 is additionally provided in the partial depolymerization section 730 and the solid-liquid separation section 740 shown in Fig. 10.

[0105] The stirring blades 870 and / or the cavitation device 762 mechanically mix or stir the polymer such as PET supplied from the polymer supply unit 820 and the depolymerization agent such as EG supplied from the depolymerization agent supply unit 830 in the partial depolymerization reaction tank 810, thereby promoting mechanical mixing in the initial or early stage of the depolymerization reaction carried out by the partial depolymerization unit 730. This mechanical mixing not only efficiently advances the depolymerization reaction, but also finely disintegrates the PET flakes and the like into a slurry. The finely disintegrated PET slurry can pass through the polymer removal unit 850 composed of a strainer and a valve, and is removed from the partial depolymerization reaction tank 810 and sent to the depolymerization reaction tank 300.

[0106] The cavitation device 762 is provided, for example, on a supply path through which the depolymerization agent supply unit 830 supplies a depolymerization agent such as EG to the partial depolymerization reaction tank 810. The cavitation device 762 introduces a pressure difference into the liquid depolymerization agent such as EG, causing cavitation (cavitation phenomenon) accompanied by the generation and disappearance of bubbles. Typically, minute bubbles accompanying cavitation mechanically mix the polymer such as PET and the depolymerization agent such as EG in the partial depolymerization reaction tank 810. If it is difficult to provide the cavitation device 762 in the first depolymerization reaction tank 301, another cavitation tank incorporating the cavitation device 762 may be connected to the partial depolymerization reaction tank 810. In this case, mechanical mixing by the cavitation device 762 is performed in the cavitation tank, and the finely divided PET, etc. are taken out from the polymer take-out unit 850 of the partial depolymerization reaction tank 810. In addition, instead of or in addition to the cavitation device 762, a bubble generating device that generates tiny bubbles (also called fine bubbles or microbubbles) using a principle different from cavitation may be used as the mechanical mixer 760.

[0107] 15, the cavitation device 762 generates minute bubbles due to cavitation in the depolymerization agent such as EG supplied by the depolymerization agent supply unit 830 into the partial depolymerization reaction tank 810. These minute bubbles are introduced into the partial depolymerization reaction tank 810 together with the depolymerization agent such as EG, and mechanically mix the polymer such as PET flakes supplied by the polymer supply unit 820 with the depolymerization agent such as EG supplied by the depolymerization agent supply unit 830. Note that when the PET flakes are too large, it is difficult to mix them with the contact type mixing blade 870, but the non-contact type cavitation device 762 can effectively mix the PET flakes regardless of their size.

[0108] FIG. 16 shows a schematic diagram of a horizontal stirring device 763 as a third embodiment of the mechanical mixer 760. The horizontal stirring device 763 constitutes the partial depolymerization section 730 in FIG. 12. The depolymerization reaction tank 300 in FIG. 12 is a vertical stirring device as shown in FIG. 1 or FIG. 4. Here, "horizontal" means that stirring is performed by a rotor that rotates around a rotation axis in a direction intersecting the vertical direction (for example, the horizontal direction), and "vertical" means that stirring is performed by a rotor (for example, a stirring blade) that rotates around a rotation axis in a direction intersecting the horizontal direction (for example, the vertical direction).

[0109] In FIG. 16 (and FIG. 17 described later), for convenience, a three-dimensional coordinate system is set with an X-axis, a Y-axis, and a Z-axis. For example, the X-axis and the Y-axis are horizontal, and the Z-axis is vertical. The horizontal mixer 763 in the illustrated example is elongated in the X-direction.

[0110] The horizontal mixing device 763 includes a container 1010 , a rotating body 1020 , and a rotation drive unit 1040 .

[0111] To the container 1010, for example, polymer PM such as PET derived from the first molded product is supplied in a molten state from the polymer preparation device 200 in FIG. 1 or FIG. 4. The container 1010 includes a polymer supply port 1011 connected to the polymer preparation device 200 and supplying the polymer PM into the container 1010, and a discharge port 1012 for discharging the polymer PM (including the unreacted depolymerization agent and depolymerized polymers such as BHET as a product) stirred (mechanically mixed) with the depolymerization agent such as EG by a rotor 1020 described later to the outside of the container 1010 and supplying it to the solid-liquid separation section 740 and / or the depolymerization reaction tank 300 in the downstream stage. A transfer pump such as a gear pump or a screw pump capable of adjusting the supply amount and supply speed of the polymer PM into the container 1010 may be connected to the polymer supply port 1011, and a transfer pump such as a gear pump or a screw pump capable of adjusting the discharge amount and discharge speed of the polymer PM out of the container 1010 may be connected to the discharge port 1012. Furthermore, the container 1010 may be provided with a temperature control unit such as a heater that controls the inside of the container 1010 to an appropriate temperature so that the polymer PM is maintained in a molten state.

[0112] 16, the container 1010 is elongated in the X direction and has, for example, a substantially rectangular YZ cross section (not shown). When multiple rotating bodies 1020 are arranged with a shift in the Y direction, the YZ cross section of the container 1010 is elongated in the Y direction (i.e., rectangular) in order to accommodate them.

[0113] 16, a polymer supply port 1011 is provided at one end of the container 1010 in the X direction (the left end in FIG. 16), and a discharge port 1012 is provided at the other end of the container 1010 in the X direction (the right end in FIG. 16). In the X direction region between the polymer supply port 1011 and the discharge port 1012, one or more air supply ports 1013 for sending a gas such as nitrogen to the gas phase in the container 1010, and one or more depolymerization agent supply ports 1014 for supplying a depolymerization agent such as EG to be mechanically mixed with the polymer PM to the gas phase in the container 1010 are provided. In addition, in the X direction region between the polymer supply port 1011 and the discharge port 1012, one or more rotors 1020 are provided to stir (mechanically mix) the polymer PM in a molten state supplied from the polymer supply port 1011 and the depolymerization agent such as EG supplied from the depolymerization agent supply port 1014.

[0114] The rotor 1020 rotates in the container 1010 to agitate the polymer PM and the depolymerization agent. The rotor 1020 includes one or more rotor plates 1021 that rotate around a rotation axis 1022 in a direction (X direction perpendicular to the Z direction in the example of FIG. 16) intersecting the vertical direction (Z direction in the example of FIG. 16). The rotor plate 1021 is, for example, a disk having a circular YZ cross section. However, the shape of the YZ cross section of the rotor plate 1021 is arbitrary, and may be, for example, an ellipse, a triangle, a rectangle, or other polygon. It is preferable that the center or center of gravity of the rotor plate 1021 in the YZ plane coincides with the center of the rotation axis 1022. In this case, the one or more rotor plates 1021 and the rotation axis 1022 are arranged coaxially. The rotor 1020 may include a screw instead of or in addition to the rotor plate 1021. When the rotating body 1020 is equipped with a screw, the polymer PM such as PET may be supplied in a solid state.

[0115] In the example of FIG. 16, the rotor 1020 includes a plurality of rotor plates 1021 spaced apart from each other in the axial direction (X direction) of the rotor shaft 1022. The axial distance between two adjacent rotor plates 1021 may be constant or may be different as shown in the figure. When the agitation of the polymer PM and the depolymerization agent progresses and a part of the polymer PM is decomposed into depolymerization polymers such as BHET, the viscosity or degree of polymerization of the polymer PM decreases. On the other hand, the closer to the inlet side of the container 1010 (i.e., the polymer supply port 1011 side), the higher the viscosity or degree of polymerization of the polymer PM, and therefore the more likely the polymer PM is to adhere to the rotor plates 1021. If the interval between the rotor plates 1021 at the inlet side of such a container 1010 is too small, the polymer PM adhered to each of the rotor plates 1021 may interfere with each other, hindering the agitation of the polymer PM (mechanical mixing with the depolymerization agent) and the rotation of the rotor 1020. Therefore, as shown in the figure, it is preferable to make the interval between the rotating plates 1021 smaller from the polymer supply port 1011 (front stage) of the container 1010 toward the discharge port 1012 (rear stage).

[0116] In this way, the polymer PM and the depolymerization agent are efficiently stirred or mixed in the rear stage (the discharge port 1012 side) where the gap between the rotating plates 1021 is narrow. When a plurality of depolymerization agent supply ports 1014 are provided, the efficiency of mechanical mixing of the polymer PM and the depolymerization agent can be further improved by increasing the amount of the depolymerization agent supplied from each depolymerization agent supply port 1014 from the front stage to the rear stage.

[0117] The rotor 1020 is rotationally driven by a rotation drive unit 1040 constituted by a motor or the like. Specifically, the rotation drive unit 1040 is connected to a rotation shaft 1022 of the rotor 1020 and drives it to rotate. When the rotation shaft 1022 is rotationally driven by the rotation drive unit 1040 in this manner, the multiple rotating plates 1021 fixed thereto rotate integrally. Then, the polymer PM supplied from the polymer supply port 1011 into the container 1010 and moving toward the discharge port 1012 is effectively mixed with the depolymerization agent supplied from the depolymerization agent supply port 1014 into the container 1010 by the multiple rotating plates 1021 rotating.

[0118] By stirring by the rotor 1020, not only the polymer PM and the depolymerization agent are mechanically mixed, but also decomposition (chemical reaction) into depolymerized polymers such as BHET progresses partially. As a result, the IV value, viscosity, and degree of polymerization of the polymer PM such as PET in the container 1010 gradually decrease from the polymer supply port 1011 toward the discharge port 1012. The position or height of the polymer PM attached to each rotating plate 1021 of the rotor 1020 indirectly represents the IV value, viscosity, and degree of polymerization of the polymer PM. Therefore, the IV value, viscosity, and degree of polymerization of the polymer PM may be grasped by detecting the highest position in the vertical direction (Z direction) of the polymer PM attached to the rotating plate 1021 by an attachment position detection unit (not shown). For example, the attachment position detection unit may detect the highest position in the vertical direction (Z direction) of the polymer PM attached to the rotating plate 1021 through light traveling in the direction (Y direction) intersecting the vertical direction (Z direction) and the rotation axis 1022 (X direction).

[0119] An agitation mode adjustment unit (not shown) may adjust the agitation mode in the container 1010 so that the deviation of the adhesion position (e.g., the highest reached position) of the polymer PM detected by the adhesion position detection unit from the desired position is reduced. The desired position here corresponds to the desired viscosity or degree of polymerization of the polymer PM in the container 1010. In other words, the agitation mode adjustment unit may adjust the agitation mode in the container 1010 so that the polymer PM in the container 1010 has the desired viscosity or degree of polymerization.

[0120] Specifically, the stirring mode adjustment unit may adjust, as the stirring mode within container 1010, at least any of the following: the amount of polymer PM and / or depolymerization agent supplied into container 1010, the supply rate of polymer PM and / or depolymerization agent supplied into container 1010, the amount discharged out of container 1010 through outlet 1012, the discharge rate out of container 1010 through outlet 1012, the rotation speed of rotor 1020, the pressure within container 1010, and the temperature within container 1010.

[0121] In addition to the adhesion position detection unit that indirectly detects the polymerization degree of the polymer PM, a polymerization degree estimation unit (not shown) that estimates the polymerization degree of the polymer PM based on the adhesion position of the polymer PM detected by the adhesion position detection unit may be provided. In this case, the stirring mode adjustment unit adjusts the stirring mode in the container 1010 so that the deviation of the polymerization degree of the polymer PM estimated by the polymerization degree estimation unit from the desired value becomes small.

[0122] FIG. 17 shows a horizontal stirrer 764 as a fourth embodiment of the mechanical mixer 760. The same components as those in FIG. 16 are given the same reference numerals, and the duplicated description is omitted. The horizontal stirrer 764 constitutes the partial depolymerization section 730 in FIG. 12. While the horizontal stirrer 763 shown in FIG. 16 is a single-tank type, the horizontal stirrer 764 shown in FIG. 17 is a multiple-tank type (two-tank type in the illustrated example). Specifically, the horizontal stirrer 764 includes a first horizontal stirrer 764A on the front or upstream side, and a second horizontal stirrer 764B on the rear or downstream side. Both the first horizontal stirrer 764A and the second horizontal stirrer 764B in the illustrated example are long in the X direction.

[0123] The first horizontal stirrer 764A and the second horizontal stirrer 764B each include the above-mentioned container 1010, a rotor 1020, and a rotation drive unit 1040. The discharge port 1012 of the first horizontal stirrer 764A is connected to the polymer supply port 1011 of the second horizontal stirrer 764B.

[0124] The rotor 1020 in the first horizontal mixer 764A and the second horizontal mixer 764B includes a plurality of rotating plates 1021 spaced apart in the axial direction (X direction) of the rotating shaft 1022. The axial distance between adjacent rotating plates 1021 in the first horizontal mixer 764A is constant, and the axial distance between adjacent rotating plates 1021 in the second horizontal mixer 764B is constant. Here, the constant distance between adjacent rotating plates 1021 in the second horizontal mixer 764B is preferably set smaller than the constant distance between adjacent rotating plates 1021 in the first horizontal mixer 764A. In the second horizontal mixer 764B in the latter stage where the mixing of the polymer PM and the depolymerization agent (and the decomposition into depolymerized substances such as BHET) has progressed, the viscosity or degree of polymerization of the polymer PM is low, so the distance between the rotating plates 1021 can be made smaller than that in the first horizontal mixer 764A.

[0125] In this way, the polymer PM and the depolymerization agent are efficiently stirred or mixed in the second horizontal mixer 764B in the rear stage having a narrow gap between the rotating plates 1021. Here, by increasing the amount of the depolymerization agent supplied from the depolymerization agent supply port 1014 in the second horizontal mixer 764B compared to the amount of the depolymerization agent supplied from the depolymerization agent supply port 1014 in the first horizontal mixer 764A, the efficiency of mechanical mixing of the polymer PM and the depolymerization agent can be further improved.

[0126] FIG. 18 is a schematic diagram showing a fourth embodiment of the recycling system according to the present disclosure. The same components as those in the above-mentioned embodiments are given the same reference numerals, and the description of the same purpose is omitted. The recycling system according to the fourth embodiment includes a partial depolymerization section 730, a solid-liquid separation section 740, a deteriorated material recovery section 750, and a mechanical recycling device 900. The mechanical recycling device 900 is configured similarly to the second embodiment in FIG. 5. Moreover, the partial depolymerization section 730, the solid-liquid separation section 740, and the deteriorated material recovery section 750 are configured similarly to the third embodiment in FIG. 7 to FIG. 12.

[0127] In this embodiment, the surfaces of solid materials such as PET flakes, which are prone to quality deterioration, are partially decomposed, and solids of relatively high quality are separated. By subjecting the high-quality solids to mechanical recycling in this way, the quality of the recycled products can be stabilized.

[0128] Moreover, according to this embodiment, high-quality solid material (solid content) can be stably obtained by effectively removing surface parts that are prone to quality deterioration through the action of the partial depolymerization section 730 and the solid-liquid separation section 740. This eliminates the need to use the chemical recycling apparatus 100 (FIG. 7), which is typically suitable for low-quality solid materials, and allows recycling to be performed quickly and efficiently using the mechanical recycling apparatus 900, which has a simpler configuration and lower operating costs.

[0129] Furthermore, the recycling system according to this embodiment can accept low-quality fixed materials such as PET flakes because the surface parts that are prone to quality deterioration can be effectively removed by the action of the partial depolymerization section 730 and the solid-liquid separation section 740. In this way, according to this embodiment, a highly versatile recycling system that can handle a wide range of fixed materials can be provided.

[0130] FIG. 19 is a schematic diagram showing a fifth embodiment of the recycling system according to the present disclosure. The same components as those in the above-mentioned embodiments are given the same reference numerals, and the description of the same purpose is omitted. In the recycling system according to the fifth embodiment, the quality determination section 710 and the material sorting section 720 in the second embodiment of FIG. 5 are replaced by a partial depolymerization section 730 and a solid-liquid separation section 740.

[0131] The high-quality solid fraction separated by the solid-liquid separation section 740 is efficiently recycled by a mechanical recycling process (mechanical recycling apparatus 900) that has a low quality improvement effect but requires a simple device, and the low-quality liquid fraction separated by the solid-liquid separation section 740 is recycled while its quality is improved by a chemical recycling process (chemical recycling apparatus 100) that has a high quality improvement effect. Since the liquid fraction has already been depolymerized in the partial depolymerization section 730, it may be directly supplied to the foreign matter removal apparatuses 340-360 without passing through the depolymerization reaction tank 300 in the chemical recycling apparatus 100. In the foreign matter removal apparatuses 340-360, contaminants contained in the liquid fraction are effectively removed.

[0132] 20 is a schematic diagram of a sixth embodiment of the recycle system according to the present disclosure. The same components as those in the above-mentioned embodiments are given the same reference numerals, and the description of the same purpose is omitted. In the recycle system according to the sixth embodiment, a first partial decomposition-polymerization section 731 and a second partial decomposition-polymerization section 732 similar to the partial decomposition-polymerization section 730 are provided, and a first solid-liquid separation section 741 and a second solid-liquid separation section 742 similar to the solid-liquid separation section 740 are provided.

[0133] Solid materials such as PET flakes are supplied to a first partial decomposition / polymerization section 731 and a first solid-liquid separation section 741. The low-quality liquid fraction separated by the first solid-liquid separation section 741 is recovered by a deteriorated material recovery section 750. On the other hand, the medium-quality solid fraction separated by the first solid-liquid separation section 741 is supplied to a second partial decomposition / polymerization section 732 and a second solid-liquid separation section 742.

[0134] The high-quality solid fraction separated by the second solid-liquid separation section 742 is efficiently recycled by a mechanical recycling process (mechanical recycling apparatus 900) which has a low quality improvement effect but requires a simple apparatus, and the medium-quality liquid fraction separated by the second solid-liquid separation section 742 is recycled while its quality is improved by a chemical recycling process (chemical recycling apparatus 100) which has a high quality improvement effect. Since the liquid fraction has already been depolymerized in the second depolymerization polymerization section 732, it may be directly supplied to the foreign matter removal apparatuses 340-360 without passing through the depolymerization reaction tank 300 in the chemical recycling apparatus 100. In the foreign matter removal apparatuses 340-360, contaminants contained in the liquid fraction are effectively removed.

[0135] In this embodiment, the low-quality liquid fraction separated by the first solid-liquid separation section 741 is not supplied to the chemical recycling apparatus 100, and the medium-quality liquid fraction separated by the second solid-liquid separation section 742 in the second stage is supplied to the chemical recycling apparatus 100, thereby reducing the burden on the chemical recycling apparatus 100.

[0136] The quality determination section 710 and / or the material sorting section 720 illustrated in the second embodiment in Fig. 5 may be combined with the partial depolymerization section 730 and / or the solid-liquid separation section 740 illustrated in the third embodiment in Fig. 7, the fourth embodiment in Fig. 18, the fifth embodiment in Fig. 19, and the sixth embodiment in Fig. 20 in various ways. Some specific examples of such aspects are shown below. The same components as those in the above-mentioned embodiments are denoted by the same reference numerals, and the description of the same meaning is omitted.

[0137] 21 is a schematic diagram showing a seventh embodiment of the recycling system according to the present disclosure. In this embodiment, high-quality materials sorted by the material sorting section 720 are supplied to the mechanical recycling apparatus 900, and low-quality materials sorted by the material sorting section 720 are supplied to the partial depolymerization section 730 and the solid-liquid separation section 740. Then, the solid content including high-quality PET and the like separated by the solid-liquid separation section 740 is supplied to the mechanical recycling apparatus 900 together with the high-quality materials sorted by the material sorting section 720.

[0138] In this embodiment, the high-quality material selected by the material selection unit 720 is not subjected to partial decomposition polymerization processing by the partial decomposition polymerization unit 730, so that it is possible to prevent removal of high-quality PET and the like in the partial decomposition polymerization processing. Note that a chemical recycling device 100 may be provided instead of the mechanical recycling device 900 in this embodiment.

[0139] 22 is a schematic diagram of an eighth embodiment of the recycling system according to the present disclosure. In this embodiment, solid materials such as PET flakes are supplied to a partial depolymerization section 730 and a solid-liquid separation section 740. The low-quality liquid fraction separated by the solid-liquid separation section 740 is collected by a deteriorated material recovery section 750. Meanwhile, the solid fraction separated by the solid-liquid separation section 740 is supplied to a quality determination section 710 and a material sorting section 720.

[0140] The high-quality materials selected by the material sorting unit 720 are recycled efficiently by a mechanical recycling process (mechanical recycling device 900) which has a low quality improvement effect but requires simple equipment, and the low-quality materials selected by the material sorting unit 720 are recycled while their quality is improved by a chemical recycling process (chemical recycling device 100) which has a high quality improvement effect.

[0141] In this embodiment, the low-quality liquid fraction separated by the solid-liquid separation section 740 is not supplied to the chemical recycling apparatus 100, and the low-quality material sorted by the material sorting section 720 (however, the quality is higher than that of the liquid fraction separated by the solid-liquid separation section 740) is supplied to the chemical recycling apparatus 100, thereby reducing the burden on the chemical recycling apparatus 100.

[0142] FIG. 23 is a schematic diagram of a ninth embodiment of the recycling system according to the present disclosure. In this embodiment, solid materials such as PET flakes are supplied to a quality determination section 710 and a material sorting section 720. The high-quality material sorted by the material sorting section 720 is supplied to a first partial decomposition / polymerization section 731 (high-quality material part decomposition / polymerization section) and a first solid-liquid separation section 741. The solid content separated by the first solid-liquid separation section 741 is supplied to a mechanical recycling apparatus 900, and the liquid content separated by the first solid-liquid separation section 741 is supplied to a chemical recycling apparatus 100. The low-quality material sorted by the material sorting section 720 is supplied to a second partial decomposition / polymerization section 732 (low-quality material part decomposition / polymerization section) and a second solid-liquid separation section 742. The solid component separated by the second solid-liquid separation section 742 is supplied to the chemical recycling apparatus 100, and the liquid component separated by the second solid-liquid separation section 742 is recovered by the deteriorated material recovery section 750.

[0143] The present disclosure has been described above based on the embodiments. Various modifications are possible to the combinations of the components and processes in the exemplary embodiments, and it will be obvious to those skilled in the art that such modifications are included within the scope of the present disclosure.

[0144] The configuration, action, and function of each device and method described in the embodiments can be realized by hardware resources or software resources, or by the cooperation of hardware resources and software resources. For example, a processor, ROM, RAM, and various integrated circuits can be used as hardware resources. For example, programs such as an operating system and applications can be used as software resources. [Explanation of symbols]

[0145] 1 injection molding machine, 100 chemical recycling device, 200 polymer adjustment device, 300 depolymerization reaction tank, 340 foreign resin removal device, 350 colored matter removal device, 360 metal ion removal device, 400 polymerization reaction tank, 500 polymerization promotion device, 600 polymer supply section, 710 quality judgment section, 720 material selection section, 730 part decomposition polymerization section, 731 first part decomposition polymerization section, 732 second part decomposition polymerization section, 740 solid-liquid separation section, 741 first solid-liquid separation section, 742 second solid-liquid separation section, 750 deteriorated material recovery section, 810 part decomposition polymerization reaction tank, 820 solid material supply section, 830 depolymerization material supply section, 840 depolymerization polymer discharge section, 850 solid fraction removal section, 860 partition, 870 stirring blade, 880 baffle, 900 Mechanical recycling equipment, 910 heaters.

Claims

1. a quality determination unit that determines the quality of the polymer-containing solid material to be recycled based on a predetermined quality determination standard; a material sorting unit that sorts the solid material into a high-quality material determined to have a quality higher than the quality criterion and a low-quality material determined to have a quality lower than the quality criterion; a mechanical recycling device for subjecting the high-quality material to a mechanical recycling process; a chemical recycling device for subjecting the low-quality material to a chemical recycling process; A recycling system equipped with

2. 2. The recycling system according to claim 1, wherein the chemical recycling apparatus comprises: a depolymerization reaction tank that decomposes the low-quality material into depolymerized polymers by a depolymerization reaction; a foreign matter removal device that is provided downstream of the depolymerization reaction tank and removes foreign matter from the depolymerized polymers; a polymerization reaction tank that is provided downstream of the foreign matter removal device and synthesizes the depolymerized polymers into the polymers by a polymerization reaction; and a polymerization promotion device that is provided downstream of the polymerization reaction tank and increases a degree of polymerization of the polymers.

3. The recycling system according to claim 2 , wherein the mechanical recycling device uses the polymerization promoter in common with the chemical recycling device to increase the degree of polymerization of the high quality material.

4. The recycling system according to any one of claims 1 to 3, further comprising a polymer supply section provided downstream of the mechanical recycling device and the chemical recycling device, for supplying the high-quality material that has been subjected to the mechanical recycling process and the low-quality material that has been subjected to the chemical recycling process in a mixed state to a molding machine.

5. Between the material sorting unit and the mechanical recycling device, a high-quality material decomposition / polymerization unit is provided for partially decomposing the high-quality material into depolymerized polymers by a depolymerization reaction; The solid fraction obtained in the high-quality material decomposition and polymerization section is supplied to the mechanical recycling device, The liquid obtained in the high-quality material decomposition and polymerization section is supplied to the chemical recycling device. The recycling system according to any one of claims 1 to 3.

6. Between the material sorting unit and the chemical recycling device, a low-quality material decomposition / polymerization unit is provided which partially decomposes the low-quality material into depolymerized polymers by a depolymerization reaction; The solid content obtained in the low-quality material decomposition and polymerization section is supplied to the chemical recycling device. The recycling system according to any one of claims 1 to 3.

7. The recycling system according to any one of claims 1 to 3, wherein the polymer is polyethylene terephthalate.

8. determining the quality of the solid material to be recycled based on a predetermined quality determination criterion; sorting the solid material into high quality material determined to have a quality higher than the quality criterion and low quality material determined to have a quality lower than the quality criterion; subjecting the high quality material to a mechanical recycling process; subjecting the low-quality material to a chemical recycling process; A recycling method that runs through a computer.

9. determining the quality of the solid material to be recycled based on a predetermined quality determination criterion; sorting the solid material into high quality material determined to have a quality higher than the quality criterion and low quality material determined to have a quality lower than the quality criterion; subjecting the high quality material to a mechanical recycling process; subjecting the low-quality material to a chemical recycling process; A storage medium storing a recycling program for executing the above through a computer.

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