Depolymerization reaction monitoring device, depolymerization reaction monitoring method, and depolymerization reaction monitoring program

Abstract

The present invention relates to a depolymerization reaction monitoring device, a depolymerization reaction monitoring method, and a depolymerization reaction monitoring program, the depolymerization reaction monitoring device (30) comprising: a depolymerization reaction tank (300) for initiating a depolymerization reaction in which a polyester such as polyethylene terephthalate is decomposed into a depolymerized product such as bis (2-hydroxyethyl) terephthalate by a depolymerization material such as ethylene glycol; a characteristic measurement unit (33) that measures the characteristics of the depolymerization material in which the depolymerized substance is dissolved in the depolymerization reaction tank (300); and a progress monitoring unit (37) that monitors the progress of the depolymerization reaction on the basis of the characteristics of the depolymerization material measured by the characteristic measuring unit (33). The depolymerization reaction tank (300) is provided with a tank main body (31) that initiates a depolymerization reaction, and a depolymerization material circulation unit (32) that circulates a depolymerization material between the tank main body (31) and the depolymerization material circulation unit (32). The characteristic measurement unit (33) measures the characteristics of the depolymerization material in the depolymerization material circulation unit (32).

Description

Technical Field

[0001] The present invention relates to a depolymerization reaction monitoring device and the like. Background Art

[0002] Patent Document 1 discloses a method for recycling PET (polyethylene terephthalate) bottles by crushing the PET bottles to produce PET sheets that are raw materials for new PET bottles. Specifically, there are known methods of mechanical recycling in which the crushed PET bottles are heated and melted and then solid-phase polymerized to obtain PET sheets, and chemical recycling in which the crushed PET bottles are decomposed into intermediates or depolymerized products such as bis(2-hydroxyethyl)terephthalate (BHET) by depolymerization reaction and then repolymerized to obtain PET sheets.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-153176

[0006] Patent Document 2: Japanese Patent Application Publication No. 2022-27158 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In order to effectively carry out chemical recovery of PET, it is important to timely grasp the progress of chemical reactions such as depolymerization reaction and repolymerization reaction. The progress of chemical reactions can be grasped by measuring the reactants and / or products collected from the reaction tank. However, there are inconveniences such as the need for a special collection device for collecting reactants and / or products and the need to stop the chemical reaction during the collection.

[0009] The present invention has been made in view of such circumstances, and an object of the present invention is to provide a depolymerization reaction monitoring device and the like which can effectively grasp the progress of the depolymerization reaction.

[0010] Means for solving problems

[0011] In order to solve the above-mentioned problems, a depolymerization reaction monitoring device according to one embodiment of the present invention comprises: a depolymerization reaction tank for inducing a depolymerization reaction in which a depolymerization material decomposes a polyester into depolymerized products; a property measuring unit for measuring the property of the depolymerization material in which the depolymerized products are dissolved in the depolymerization reaction tank; and a progress monitoring unit for monitoring the progress of the depolymerization reaction based on the property of the depolymerized material measured by the property measuring unit.

[0012] In this method, the progress of the depolymerization reaction of the polyester in which the depolymerized product is dissolved in the depolymerized material as a reactant or catalyst can be effectively grasped by measuring the properties of the depolymerized material in the depolymerization reaction tank.

[0013] Another embodiment of the present invention is a method for monitoring a depolymerization reaction, comprising: initiating a depolymerization reaction in a depolymerization reaction tank to decompose a polyester into depolymerized products by a depolymerization material; measuring the properties of the depolymerization material in which the depolymerized products are dissolved in the depolymerization reaction tank; and monitoring the progress of the depolymerization reaction based on the measured properties of the depolymerized material.

[0014] In addition, any combination of the above-mentioned constituent elements, and forms of converting these elements into methods, devices, systems, storage media, computer programs, etc., are also included in the present invention.

[0015] Effects of the Invention

[0016] According to the present invention, the progress of the depolymerization reaction can be effectively grasped. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematically represents the structure of the chemical recycling molding system.

[0018] Figure 2 Schematic representation of the polymerization and depolymerization reactions of PET.

[0019] Figure 3 A modified example of the by-product removal device is shown.

[0020] Figure 4 A first embodiment of the depolymerization reaction monitoring device is shown.

[0021] Figure 5A as well as Figure 5B An example in which the progress of the depolymerization reaction is monitored by the progress monitoring unit is shown.

[0022] Figure 6 A second embodiment of the depolymerization reaction monitoring device is shown.

[0023] Figure 7 An example in which the depolymerized material is diluted by the depolymerized material diluting unit is shown.

[0024] Figure 8 This is a flowchart of a specific measurement sequence example in the second embodiment.

[0025] Fig. 9 A third embodiment of the depolymerization reaction monitoring device is shown.

[0026] Fig.10 This is a flowchart of a specific measurement sequence example in the third embodiment. DETAILED DESCRIPTION

[0027] Hereinafter, the method for implementing the present invention (hereinafter, also referred to as an embodiment) is described in detail with reference to the accompanying drawings. In the description and / or the accompanying drawings, the same or equivalent components, parts, processes, etc. are marked with the same symbols, and repeated descriptions are omitted. The scale and shape of each part shown in the figure are appropriately set to simplify the description, and no restrictive interpretation is made unless otherwise specified. The embodiment is an example and does not limit the scope of the present invention in any way. All the features described in the embodiment and the combination of these features are not necessarily the essential features of the present invention.

[0028] Figure 1 The structure of a chemical recovery molding system to which the depolymerization reaction monitoring device according to an embodiment of the present invention can be applied is schematically shown. The chemical recovery molding system includes a chemical recovery device 100 and an injection molding machine 1. The chemical recovery device 100 includes a polymer adjustment device 200, a depolymerization reaction tank 300, a polymerization reaction tank 400, a by-product removal device 500, and a polymer supply unit 600. The injection molding machine 1 ( Figure 1 2 are schematically shown in the figure), the polymer adjustment device 200, the depolymerization reaction tank 300, the polymerization reaction tank 400, the by-product removal device 500 and the polymer supply unit 600 are set in any number. In particular, typically, the processing performance is improved by making the number of the injection molding machine 1 and the polymerization reaction tank 400, which have a processing speed or reaction speed slower than other processing units, larger than that of other processing units, so that these processing units do not become serious bottlenecks.

[0029] The polymer adjustment device 200 adjusts the polymer such as PET constituting the first molded product such as a PET bottle for the depolymerization reaction tank 300 in the later stage. Specifically, the polymer adjustment device 200 performs processes such as crushing, heating, melting, mixing, etc. on the first molded product such as a PET bottle to adjust the polymer such as PET to a state (phase, shape, size, etc.) suitable for the depolymerization reaction in the depolymerization reaction tank 300. In addition, the first molded product may be any molded product other than a bottle such as a sheet, a film, a fiber, etc. In addition, the polymer constituting the first molded product may be any polymer or polymer such as polyester (including PET), polyamide, polyurethane, etc. other than PET.

[0030] The depolymerization reaction tank 300 decomposes the polymer such as PET adjusted by the polymer adjustment device 200 into depolymerized products through a depolymerization reaction. When the polymer supplied from the polymer adjustment device 200 is PET, BHET as an intermediate can be obtained as a depolymerized product through the depolymerization reaction in the depolymerization reaction tank 300. In addition, the depolymerized product obtained in the depolymerization reaction tank 300 may include a monomer or a polymer of the polymer. When the polymer is PET, the monomer is, for example, ethylene glycol, terephthalic acid, dimethyl terephthalate, and ethylene terephthalate. The details will be described later, but the depolymerization reaction monitoring device involved in the embodiment of the present invention is configured to include a depolymerization reaction tank 300.

[0031] like Figure 2 Schematically, in the depolymerization reaction (300) of PET as a polymer, by supplying a depolymerization material from a depolymerization material supply unit 310 ( Figure 1 ) is supplied to the depolymerization reaction tank 300 as a depolymerization material to decompose PET to obtain BHET as a depolymerized product. In addition, EG may be supplied to the polymer adjustment device 200 instead of the depolymerization material supply unit 310, or EG may be supplied to the polymer adjustment device 200 in addition to the depolymerization material supply unit 310. In order to promote the depolymerization reaction, a heater 320 ( Figure 1 ) or a heat insulator to maintain the temperature in the depolymerization reaction tank 300 at a temperature suitable for the depolymerization reaction. Figure 2 The temperature suitable for the depolymerization reaction of PET to BHET is between 180°C and 250°C, preferably between 230°C and 245°C, more preferably between 235°C and 240°C. And, Figure 2 The pressure suitable for the depolymerization reaction of PET to BHET is between normal pressure (0 MPa, G) and 0.8 MPa, G, preferably between 0.4 MPa, G and 0.6 MPa, G, and more preferably between 0.45 MPa, G and 0.55 MPa, G. In addition, the unit of pressure MPa, G is a gauge pressure. The pressure in the depolymerization reaction tank 300 is adjusted by a pump (not shown) and the like provided in parallel with the depolymerization reaction tank 300.

[0032] Since the viscosity of the fluid in the depolymerization reaction tank 300 that produces BHET having a smaller molecular weight than PET as a polymer is lower than the viscosity of the fluid in the polymerization reaction tank 400 described later that produces PET having a larger molecular weight, a low-viscosity stirring blade is used as the stirring blade 330 for stirring the fluid in the depolymerization reaction tank 300 to promote the depolymerization reaction. Examples of the low-viscosity stirring blade 330 include a propeller blade, a disk turbine blade, and a paddle blade.

[0033] At the rear section of the depolymerization reaction tank 300, there are provided impurity removal devices 340, 350, 360 for removing impurities from the fluid containing BHET as the depolymerized product as the main component. The foreign resin removal device 340 removes resins different from the target resin such as PET and / or their depolymerized products by the principle of floating separation and sedimentation removal. The coloring matter removal device 350 removes coloring matter by activated carbon or the like. The metal ion removal device 360 ​​removes metal ions by the principle of ion exchange or the like. At the rear section of the impurity removal devices 340, 350, 360, there is provided a buffer tank 370 for temporarily storing the fluid containing BHET or the like as the main component after the impurities have been removed before supplying it to the polymerization reaction tank 400.

[0034] The buffer tank 370 may be provided with a first preheater 371 for heating or keeping the depolymerized product (fluid containing BHET or the like as a main component) warm before being supplied to the polymerization reaction tank 400 at the subsequent stage. The first preheater 371 may maintain the depolymerized product at the same temperature (between 180° C. and 250° C.) as that of the heater 320 provided in parallel with the depolymerization reaction tank 300, or may maintain the depolymerized product at the same temperature (between 250° C. and 300° C.) suitable for polymerization reaction as that of the heater 410 provided in parallel with the polymerization reaction tank 400 described later. In this way, the buffer tank 370 having a preheating mechanism (first preheater 371) is provided at the upstream of the polymerization reaction tank 400 as needed, thereby typically being able to store the depolymerized product to be supplied to the polymerization reaction tank 400 whose processing speed or reaction speed is slower than that of the depolymerization reaction tank 300, the byproduct removal device 500 described later, and other processing parts while being kept at an appropriate temperature. As a result, the overall capacity of the chemical recovery device 100 is increased, and the chemical recovery device 100 can be operated stably and continuously while supplying appropriate amounts of reactants to each processing unit such as the depolymerization reaction tank 300, the polymerization reaction tank 400, the byproduct removal device 500, and the polymer supply unit 600 at an appropriate time (without causing the so-called "resin supply failure"). In addition, the preheating mechanism such as the first preheater 371 is not limited to the buffer tank 370, and can be installed in any position between the depolymerization reaction tank 300 and the polymerization reaction tank 400 (for example, the impurity removal devices 340, 350, 360) in any manner.

[0035] The polymerization reaction tank 400 synthesizes the depolymerized product such as BHET generated in the depolymerization reaction tank 300 and from which impurities have been removed by the impurity removal devices 340, 350, and 360 into a polymer by a polymerization reaction. When the depolymerized product generated in the depolymerization reaction tank 300 is BHET, PET can be obtained again as a polymer by the polymerization reaction in the polymerization reaction tank 400.

[0036] like Figure 2It is schematically shown that in the polymerization reaction (400) of BHET as a depolymerized product, EG is generated as a by-product together with PET as a polymer, i.e., a main product. This EG can be circulated to the depolymerization material supply unit 310 and used in the depolymerization reaction of PET in the depolymerization reaction tank 300. Since the EG generated in the polymerization reaction tank 400 is not wasted and can be reused on the spot (depolymerization reaction tank 300), the operation efficiency of the chemical recovery device 100 can be improved. In particular, since the purchase amount of EG used for the depolymerization reaction of PET in the depolymerization reaction tank 300 can be significantly reduced, the operation cost of the chemical recovery device 100 is reduced.

[0037] In order to promote the above-mentioned polymerization reaction, a heater 410 ( Figure 1 ) or a heat insulator to maintain the polymerization reaction tank 400 at a temperature suitable for the polymerization reaction. Figure 2 The temperature suitable for the polymerization reaction of BHET to PET 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 based on the heater 410 arranged in parallel in the polymerization reaction tank 400 is higher than the depolymerization heating temperature based on the heater 320 arranged in parallel in the depolymerization reaction tank 300. PET with a larger molecular weight and a higher melting point is generated in the polymerization reaction tank 400, but by maintaining a temperature higher than that of the depolymerization reaction tank 300 where BHET with a smaller molecular weight and a lower melting point is generated, the main product of the polymerization reaction tank 400, namely PET, is maintained in a molten state. In addition, Figure 2 The polymerization reaction of BHET to PET is preferably carried out in a vacuum state. Therefore, a vacuum pump (not shown) is provided in parallel to the polymerization reaction tank 400.

[0038] Since the viscosity of the fluid in the polymerization reaction tank 400 that produces PET having a relatively large molecular weight is higher than the viscosity of the fluid in the depolymerization reaction tank 300 that produces BHET having a smaller molecular weight than PET as a polymer, a high-viscosity stirring blade is used as a stirring blade 420 for stirring the fluid in the polymerization reaction tank 400 to promote the polymerization reaction. Examples of the high-viscosity stirring blade 420 include an anchor blade and a helical ribbon blade.

[0039] As a numerical value associated with the degree of polymerization of polymers such as PET, IV (Intrinsic viscosity) value or intrinsic viscosity is known. The IV value (dL / g) is also used as an indicator of the use of the polymer. In PET, if the IV value is about 0.72 or more, it can be used for bottles, if the IV value is about 0.65 or more, it can be used for sheets, films, etc., and if the IV value is about 0.58 or more, it can be used for fibers. In this embodiment, the purpose is to finally obtain PET with an IV value that can be used for bottles and sheets. As described later, since the IV value is also increased in the by-product removal device 500 at the rear stage of the polymerization reaction tank 400, the IV value of the PET synthesized in the polymerization reaction tank 400 can 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.

[0040] A buffer tank 430 for temporarily storing the polymer synthesized in the polymerization reaction tank 400 before supplying to the by-product removal device 500 and / or the polymer supply unit 600 at the subsequent stage may be provided at the subsequent stage. A second preheater 431 for heating or keeping the polymer warm before supplying to the by-product removal device 500 and / or the polymer supply unit 600 at the subsequent stage may be provided to the buffer tank 430. The second preheater 431 may maintain the polymer at the same temperature (between 250° C. and 300° C.) as the heater 410 provided in parallel with the polymerization reaction tank 400, or at the same temperature (between 250° C. and 290° C.) suitable for polymerization reaction as the heater 520 provided in parallel with the later-described by-product removal device 500, or at the same temperature (between 250° C. and 290° C.) as the heater 620 provided in parallel with the later-described polymer supply unit 600.

[0041] Thus, by installing the buffer tank 430 having a preheating mechanism (second preheater 431) at the front stage of the byproduct removal device 500 and / or the polymer supply unit 600 as needed, the polymer to be fed to the byproduct removal device 500 and / or the polymer supply unit 600 can be stored while being kept at an appropriate temperature. As a result, the capacity of the chemical recovery device 100 as a whole is increased, and the chemical recovery device 100 can be operated stably and continuously while supplying an appropriate amount of reactants to each processing unit such as the depolymerization reaction tank 300, the polymerization reaction tank 400, the byproduct removal device 500, and the polymer supply unit 600 in a timely manner (without causing the so-called "resin supply cut"). In addition, the preheating mechanism such as the second preheater 431 is not limited to the buffer tank 430, and can be installed in any manner at any position between the polymerization reaction tank 400 and the byproduct removal device 500 and / or any position between the byproduct removal device 500 and the polymer supply unit 600.

[0042] A by-product removal device 500 is provided at the rear section of the polymerization reaction tank 400 (and at the front section of the polymer supply unit 600 described later) for passing PET (main product) and EG (by-product) generated by the polymerization reaction in the polymerization reaction tank 400 and removing EG as a by-product. The by-product removal device 500 shown in the figure is provided with a plurality of linear members 510 extending from the top to the bottom. Due to the increased surface area due to the plurality of linear members 510, the volatilization of EG attached to the surface of each linear member 510 is promoted, and EG is effectively separated and removed from the high-viscosity PET.

[0043] This EG can be circulated to the depolymerization material supply unit 310 and used in the depolymerization reaction of PET in the depolymerization reaction tank 300. Since the EG separated and removed in the by-product removal device 500 is not wasted but can be reused on site (depolymerization reaction tank 300), the operation efficiency of the chemical recovery device 100 can be improved. In particular, since the purchase amount of EG used for the depolymerization reaction of PET in the depolymerization reaction tank 300 can be significantly reduced, the operation cost of the chemical recovery device 100 is reduced.

[0044] Furthermore, since PET with a relatively low degree of polymerization (i.e., IV value) and BHET that has not reacted in the polymerization reaction tank 400 are also attached to the surface of each linear member 510, the same polymerization reaction as in the polymerization reaction tank 400 can be efficiently performed through a large surface area. Therefore, the IV value of PET, which is a main product, is increased by passing through the by-product removal device 500. Specifically, the IV value of PET after passing through the by-product removal device 500 is 0.7 or more, preferably 0.8 or more, and more preferably 0.85 or more.

[0045] In order to promote the polymerization reaction, a heater 520 ( Figure 1 ) or a heat insulator, the temperature inside the byproduct removal device 500 is maintained at a temperature suitable for the polymerization reaction. Specifically, the heating temperature by the heater 520 is between 250°C and 290°C, preferably between 260°C and 280°C. Here, the heating temperature by the heater 520 provided in parallel in the byproduct removal device 500 is preferably higher than the polymerization heating temperature by the heater 410 provided in parallel in the polymerization reaction tank 400. In the byproduct removal device 500, the polymerization reaction progresses further than in the polymerization reaction tank 400, and as a result, the molecular weight of PET as a polymer becomes larger and the melting point becomes higher. Therefore, by maintaining the temperature inside the byproduct removal device 500 higher than that inside the polymerization reaction tank 400, the PET as a product of the byproduct removal device 500 can be maintained in a molten state. In addition, around the piping etc. between the polymerization reaction tank 400 and the by-product removal device 500, at least a heater or a heat retainer as a second heater that heats or retains the temperature to the polymerization heating temperature based on the heater 410 provided in parallel with the polymerization reaction tank 400 may be provided. Also, similarly to the polymerization reaction in the polymerization reaction tank 400, the polymerization reaction in the by-product removal device 500 is preferably performed in a vacuum state. Therefore, a vacuum pump etc. not shown in the figure may be provided in parallel with the by-product removal device 500. By placing the by-product removal device 500 in a vacuum state (decompressed state), EG as a by-product can be effectively removed.

[0046] In addition, the structure of the by-product removal device 500 is not limited to Figure 1 For example, Figure 3 The "horizontal double-shaft" stirring device shown can also be used as the by-product removal device 500. The stirring device has a vertical axis. Figure 3 The two stirring blades rotate around the two rotating shafts to stir the PET and EG as stirring objects. The two stirring blades promote the volatilization of EG, so that EG can be effectively separated and removed from the high-viscosity PET. Figure 3 The details of the stirring device are disclosed in Japanese Patent No. 2925599 which is incorporated herein by reference.

[0047] The polymer supply unit 600 supplies the polymer such as PET synthesized in the polymerization reaction tank 400 (or the polymerization reaction tank 400 and the by-product removal device 500) to the injection molding machine 1 for molding the second molded product such as the PET bottle. The polymer supply unit 600 is equipped with a delivery pump 610 such as a gear pump or a screw pump, and the delivery pump 610 is suitable for supplying the high-purity and high-viscosity (i.e., high degree of polymerization or high IV value) PET after the EG as a by-product in the by-product removal device 500 is removed to the injection molding machine 1 while maintaining the molten state.

[0048] The polymer supply unit 600 is provided with a heater 620 or a heat retainer as a first heater for heating or heat retaining the polymer such as PET delivered to the injection molding machine 1 by the delivery pump 610 to maintain it in a molten state. Specifically, the heating temperature by the heater 620 is between 250° C. and 290° C., 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 unit 600 is preferably higher than the second heating temperature by the second heater such as the heater 410 provided in parallel with the polymerization reaction tank 400, the heater 520 provided in parallel with the by-product removal device 500, or a heater (not shown) provided between the polymerization reaction tank 400 and the by-product removal device 500. The polymerization reaction started in the polymerization reaction tank 400 gradually proceeds and is completed in the by-product removal device 500. As a result, the molecular weight of the polymer such as PET in the polymer supply unit 600 becomes larger and the melting point becomes higher than that in the polymerization reaction tank 400 and the by-product removal device 500. Therefore, by setting the first heating temperature in the polymer supply unit 600 higher than the previous second heating temperature, a polymer such as PET having a high viscosity (i.e., a high degree of polymerization or a high IV value) and a high melting point can be maintained in a molten state.

[0049] A temperature gradient may be provided so that the heating temperature gradually increases from the polymerization reaction tank 400 to the polymer supply unit 600. For example, by increasing the heating temperature of a heater (not shown) provided between the polymerization reaction tank 400 and the by-product removal device 500 compared to the heating temperature of a heater 410 provided in parallel with the polymerization reaction tank 400, increasing the heating temperature of a heater 520 provided in parallel with the by-product removal device 500 compared to the heating temperature of the heater (not shown), and increasing the heating temperature of a heater 620 provided in the polymer supply unit 600 compared to the heating temperature of the heater 520, it is possible to reliably maintain a polymer such as PET having a high melting point in a molten state from the polymerization reaction tank 400 to the polymer supply unit 600. In addition, a heater that heats or keeps a polymer such as PET warm to maintain it in a molten state may be provided between the polymer supply unit 600 and the injection molding machine 1.

[0050] The injection molding machine 1 molds the polymer such as PET in a molten state generated in the chemical recovery device 100 into a second molded product. The second molded product may be of the same type or different type as the first molded product that has been subjected to a treatment such as pulverization in the polymer adjustment device 200. For example, both the first molded product and the second molded product may be PET bottles. In addition, 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, a film, or a fiber. Generally, in mechanical recovery, the IV value of the second molded product after recovery will be lower than the IV value of the first molded product before recovery, but according to the chemical recovery device 100 involved in this embodiment, which is equipped with devices for increasing the IV value such as the impurity removal device 340, 350, 360 and the by-product removal device 500, the IV value of the second molded product after recovery can be made higher than the IV value of the first molded product before recovery. For example, according to this embodiment, it is also possible to recover the PET fiber with a low IV value as the first molded product into a PET bottle with a high IV value as the second molded product.

[0051] The injection molding machine 1 molds a 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 the entire contents of the document (Japanese Patent Application No. 2020-130985) filed on July 31, 2020 by reference. Figure 1 As schematically shown, a plurality of injection molding machines 1 may be installed in parallel. In addition, the molding machine to which the molten resin and the like are supplied from the chemical recovery device 100 is not limited to an injection molding machine, but may be any molding machine (for example, a compression molding machine).

[0052] In the present embodiment as described above, the polymer resynthesized in the polymerization reaction tank 400 is not made into sheets or pellets, but is supplied as it is to the injection molding machine 1 through the polymer supply unit 600. Since the cooling process and heating process associated with the sheets or pellets as in the past are not required, the molded products such as PET bottles can be recovered with less energy than in the past.

[0053] In the chemical recovery device 100 of this embodiment, since the polymer resynthesized in the polymerization reaction tank 400 is supplied as it is to the injection molding machine 1, it is necessary to quickly achieve the IV value of the polymer required for its molded product (second molded product). In this embodiment, in addition to the polymerization reaction tank 400, a byproduct removal device 500 having a function of promoting the polymerization reaction and increasing the IV value of the polymer is provided, so that this requirement can also be fully met.

[0054] exist Figure 1In the example of FIG. 1 , only one of each of the polymer adjustment device 200, the depolymerization reaction tank 300, the polymerization reaction tank 400, the byproduct removal device 500, and the polymer supply unit 600 is provided, but multiple of each may be provided. Such multiple processing units can perform the same processing in parallel, so the processing performance of the processing unit group can be improved. In addition, the difference in processing speed or reaction speed between the processing units can be reduced by increasing the number of slower processing units.

[0055] Furthermore, one or more processing units may receive materials from the preceding processing unit instead of or in addition to receiving materials from the preceding processing unit. Figure 1 The chemical recovery molding system shown can be supplied with external materials at different places or facilities. For example, when a plurality of polymerization reaction tanks 400 are provided, a portion of them can be supplied with depolymers from the depolymerization reaction tank 300, while another portion can be supplied with depolymers prepared from the outside (synonymous with depolymers supplied from the depolymer supply unit 300A described later). Similarly, when a plurality of by-product removal devices 500 and / or polymer supply units 600 are provided, a portion of them can be supplied with polymers from the polymerization reaction tank 400, while another portion can be supplied with polymers prepared from the outside (synonymous with polymers supplied from the polymer supply unit 400A described later). In this way, by allowing the reception of external materials at each stage of the processing in the chemical recovery molding system, the flexibility of the chemical recovery molding system can be ensured and the efficient operation can be ensured.

[0056] Figure 4 The first embodiment of the depolymerization reaction monitoring device 30 according to the present invention is shown. The depolymerization reaction monitoring device 30 is configured to include the above-mentioned depolymerization reaction tank 300. The depolymerization reaction tank 300 initiates a depolymerization reaction in which the polyester is decomposed into depolymerized products by the depolymerization material. Figure 2 Likewise, the polyester is polyethylene terephthalate (PET), the depolymerized material is ethylene glycol (EG), and the depolymer is bis(2-hydroxyethyl)terephthalate (BHET).

[0057] However, the present invention can also be applied to combinations of different polyesters, depolymerization materials and depolymers. For example, the polyester can be polybutylene acrylate (PPT), the depolymerization material can be propylene glycol (PG), and the depolymerization product can be bis (2-hydroxypropyl) terephthalate (BHPT). In addition, the polyester can be polybutylene terephthalate (PBT), the depolymerization material can be butanediol (BG), and the depolymerization product can be bis (2-hydroxybutyl) terephthalate (BHBT). Such a combination of polyesters, depolymerization materials and depolymers has the following common characteristics: the product of the depolymerization reaction, i.e., the depolymerization product (BHET, BHPT, BHBT, etc.) is soluble in the reactant or catalyst of one side of the depolymerization reaction, i.e., the depolymerization material (EG, PG, BG, etc.), and on the other hand, the reactant of the other side of the depolymerization reaction, i.e., the polyester (PET, PPT, PBT, etc.), is insoluble in the depolymerization material (EG, PG, BG, etc.).

[0058] Furthermore, as long as the same characteristics can be observed, the depolymerization reaction monitoring device 30 according to the present embodiment can also be used to monitor the progress of the depolymerization reaction of polymers other than polyesters such as polyamide and polyurethane. That is, as long as the depolymerization product, i.e., the depolymerization product, is dissolved in the depolymerization material, i.e., the reactant or catalyst of one side of the depolymerization reaction, and the polymer, i.e., the reactant of the other side of the depolymerization reaction, is not dissolved in the depolymerization material, the depolymerization reaction monitoring device 30 according to the present embodiment can be applied.

[0059] Thus, the depolymerization reaction monitoring device 30 according to the present embodiment is not limited to being set Figure 1 The depolymerization reaction tank 300 in the chemical recycling molding system shown can be applied to the depolymerization reaction tank 300 set in any system and the depolymerization reaction tank 300 of any monomer. Figure 4 In the example, only one depolymerization reaction monitoring device 30 is provided at the side of the depolymerization reaction tank 300, but any number (for example, multiple) may be provided at any position (for example, the bottom surface) other than the side of the depolymerization reaction tank 300. In addition, the depolymerization reaction monitoring device 30 may be provided at the rear section of the depolymerization reaction tank 300 and the front section of the polymerization reaction tank 400. For example, the depolymerization reaction monitoring device 30 may be provided at a position other than the depolymerization reaction tank 300. Figure 1 The piping between the depolymerization reaction tank 300 and the polymerization reaction tank 400, the buffer tank 370, or the buffer tank 370 may be installed in the depolymerization reaction tank 300 instead of being installed in the depolymerization reaction tank 300. Figure 1 The piping between the depolymerization reaction tank 300 and the polymerization reaction tank 400, and the buffer tank 370. When a plurality of depolymerization reaction tanks 300 are connected in parallel, the average value of the progress of the depolymerization reaction in the plurality of depolymerization reaction tanks 300 can be grasped in the buffer tank 370 or the like in the subsequent stage for collecting the depolymerization product liquid.

[0060] When a plurality of depolymerization reaction tanks 300 are connected in series or in parallel, any number of depolymerization reaction monitoring devices 30 may be provided at any position of each depolymerization reaction tank 300. The monitoring results of each depolymerization reaction monitoring device 30 in the depolymerization reaction tank 300 (particularly, the measurement results of the characteristic measurement unit 33 and the monitoring results of the progress monitoring unit 37 described later) are preferably shared or summarized among the plurality of depolymerization reaction tanks 300. For example, when a plurality of depolymerization reaction tanks 300 are connected in series, the progress of each stage of the depolymerization reaction can be accurately grasped by each depolymerization reaction monitoring device 30 provided in each corresponding depolymerization reaction tank 300. According to the progress of the depolymerization reaction at each stage, the retention time of the reaction solution and / or the product solution in each depolymerization reaction tank 300, and the movement timing and movement speed of the reaction solution and / or the product solution between adjacent depolymerization reaction tanks 300 can be accurately adjusted.

[0061] The depolymerization reaction tank 300 includes a tank body 31 for initiating a depolymerization reaction of a polyester or a polymer, and a depolymerization material flow section 32 for flowing a depolymerization material such as EG between the tank body 31 and the like. The depolymerization material flow section 32 constitutes a flow path for the depolymerization material such as EG outside the tank body 31. As shown in the figure, one end 321 and the other end 322 of the tubular depolymerization material flow section 32 are connected to different parts of the tank body 31. As described later, the depolymerization material such as EG can flow from the one end 321 to the other end 322 of the depolymerization material flow section 32, or can flow from the other end 322 to the one end 321 of the depolymerization material flow section 32.

[0062] The depolymerized material flow section 32 is provided with a property measuring section 33 , an intrusion preventing section 34 , a direction switching section 35 , and a cooling section 36 .

[0063] The property measuring unit 33 measures the property of the depolymerization material such as EG in which the depolymerized product such as BHET is dissolved in the depolymerization reaction tank 300. Specifically, the property measuring unit 33 measures the property of the depolymerization material such as EG in the depolymerization material flow unit 32.

[0064] Figure 4The characteristic measuring unit 33 in the example measures the optical characteristics of the depolymerization material such as EG in the depolymerization material circulation unit 32. The characteristic measuring unit 33 includes a light source 331, a light receiving unit 332, and a window 333. The light source 331 emits light of any intensity, pattern, wave number, wavelength, frequency, and other forms suitable for measuring the optical characteristics of the depolymerization material such as EG in which the depolymerization material such as BHET is dissolved. The light from the light source 331 enters the interior of the depolymerization material circulation unit 32 through the light-transmitting window 333 constituting a part of the tube wall of the tubular depolymerization material circulation unit 32 and irradiates the depolymerization material such as EG. The light is subjected to optical effects such as reflection, refraction, absorption, scattering, diffraction, polarization, interference, and dispersion according to the optical characteristics of the depolymerization material such as EG in which the depolymerization material such as BHET is dissolved. The light receiving unit 332 receives the light subjected to such optical effects through the window 333. In addition, borosilicate glass, cobalt glass, quartz, and aluminate glass are exemplified as preferred materials for the window 333. The light received by the light receiving unit 332 shows the optical properties of the depolymerized material such as EG in which the depolymerized product such as BHET is dissolved. In this way, the refractive index and the spectrum are exemplified as the optical properties that can be measured by the property measuring unit 33. In this embodiment, an example in which the property measuring unit 33 measures the refractive index of the depolymerized material such as EG in which the depolymerized product such as BHET is dissolved is described.

[0065] The refractive index measured by the characteristic measuring unit 33 is provided to the progress monitoring unit 37 composed of a computer and a processor. The progress monitoring unit 37 monitors the progress of the depolymerization reaction in the depolymerization reaction tank 300 (especially the tank body 31) based on the optical characteristics such as the refractive index and other characteristics of the depolymerization material such as EG measured by the characteristic measuring unit 33.

[0066] Figure 5A as well as Figure 5B FIG. 4 shows an example of monitoring the progress of the depolymerization reaction by the progress monitoring unit 37. Figure 5A As shown, there is a correlation such as a proportional relationship between the refractive index measured by the characteristic measuring unit 33 and the concentration of the depolymerized product such as BHET in the depolymerized material such as EG to be measured ( Figure 5A The points (○) in the figure are examples of measured values. As described above, in the depolymerization reaction tank 300 (particularly the tank body 31), PET is decomposed by EG as a depolymerization material, thereby obtaining BHET as a depolymerization product. Therefore, the concentration of BHET indicates the progress of the depolymerization reaction of PET. That is, the progress monitoring unit 37 can monitor the progress of the depolymerization reaction of PET based on the refractive index measured by the characteristic measuring unit 33. Figure 5A By understanding the concentration of depolymerized products such as BHET through such correlation, the progress of the depolymerization reaction of polymers such as PET can be identified. Figure 5B As shown, the progress monitoring unit 37 can Figure 5AThe total amount of BHET generated in the depolymerization reaction tank 300 was calculated based on the concentration of BHET identified in the reaction tank 300 and expressed as a time-dependent change relative to the reaction time ( Figure 5B The points (○) in the figure are examples of measured values). Figure 5A , Figure 5B The monitoring results of the progress monitoring unit 37 can be provided to Figure 1 The controller of the chemical recovery molding system and the chemical recovery device 100 can also be displayed on a management screen and an operation screen that can be browsed by their managers and operators to control them.

[0067] In addition, the property measuring unit 33 may also measure the non-optical properties of the depolymerized material such as EG in which the depolymerized product such as BHET is dissolved. For example, the property measuring unit 33 may measure the electrical properties of the depolymerized material such as EG in which the depolymerized product such as BHET is dissolved in the depolymerization reaction tank 300. In this case, instead of Figure 4 Instead of the optical characteristic measuring section 33 in the depolymerization material flow section 32, a characteristic measuring section having an electrode that electrically interacts with (for example, contacts) the depolymerization material such as EG in the depolymerization material flow section 32 is provided. Furthermore, as long as the characteristics of the depolymerization material such as EG can be measured without collecting the depolymerization material from the depolymerization material flow section 32 (depolymerization reaction tank 300), the method of the characteristic measuring section 33 is not limited.

[0068] Furthermore, if the polymers such as PET which are not dissolved in the depolymerized material such as EG and remain in the tank body 31 do not interfere with the measurement, the characteristic measurement section 33 may be provided in parallel with the tank body 31 instead of the depolymerized material flow section 32. Figure 4 Such an optical characteristic measuring section 33 has an undesirable effect on the measuring light such as diffuse reflection caused by residual polymers such as PET. Therefore, the characteristic measuring section 33 is preferably provided in the depolymerized material flow section 32 outside the tank body 31, and is more preferably provided with an intrusion prevention section 34 described below.

[0069] The intrusion prevention section 34 includes a first filter 341 provided on the side of one end 321 of the tubular depolymerization material flow section 32 and a second filter 342 provided on the side of the other end 322 of the tubular depolymerization material flow section 32. The first filter 341 and the second filter 342 prevent insoluble matter that is not dissolved in the depolymerization material such as EG from intruding from the tank body 31 into the depolymerization material flow section 32. As described above, examples of insoluble matter that is insoluble in the depolymerization material such as EG include polyesters such as PET, which are reactants of the depolymerization reaction, polymers, and oligomers generated by partial depolymerization of these. In this way, the insoluble matter that may hinder the optical measurement of the characteristic measurement section 33 in the depolymerization material flow section 32 can be effectively removed by the first filter 341 and / or the second filter 342.

[0070] The direction switching section 35 is composed of a backwash pump or the like that can switch the flow direction of the depolymerized material such as EG in the tubular depolymerized material flow section 32 between a first direction from the one end 321 toward the other end 322 and a second direction from the other end 322 toward the one end 321, so as to prevent clogging of the first filter 341 and / or the second filter 342. The direction switching section 35 allows the depolymerized material such as EG to flow in the first direction, thereby returning the insoluble matter captured by the second filter 342 at the other end 322 to the tank body 31, thereby eliminating clogging of the second filter 342. Furthermore, the direction switching section 35 allows the depolymerized material such as EG to flow in the second direction, thereby returning the insoluble matter captured by the first filter 341 at the one end 321 to the tank body 31, thereby eliminating clogging of the first filter 341. In order to avoid clogging of both the first filter 341 and the second filter 342 , the direction switching unit 35 preferably repeatedly or periodically switches the flow direction of the depolymerized material such as EG in the depolymerized material flow unit 32 between the first direction and the second direction.

[0071] In addition, the backwash pump and the like constituting the direction switching section 35 may be operated only before or during the measurement by the characteristic measuring section 33, and may be stopped at other times. When the backwash pump and the like constituting the direction switching section 35 are operated, the depolymerized material such as EG, which is the measurement object to be measured by the characteristic measuring section 33, is input from the tank body 31 at one of the one end 321 and the other end 322 of the depolymerized material flow section 32. At this time, the "old" depolymerized material originally existing in the depolymerized material flow section 32 is discharged from the other of the one end 321 and the other end 322 of the depolymerized material flow section 32 into the tank body 31, so that the clogging of the other of the first filter 341 and the second filter 342 provided therein is eliminated. Furthermore, the characteristic measuring section 33 can perform measurement on the "new" depolymerized material newly input from the tank body 31.

[0072] The cooling section 36 cools the depolymerized material such as EG in the tubular depolymerized material flow section 32. The optical characteristics such as the refractive index and other characteristics that can be measured by the characteristic measuring section 33 depend on the temperature of the depolymerized material such as EG to be measured. Therefore, the cooling section 36 stabilizes the measurement accuracy of the characteristic measuring section 33 by cooling the depolymerized material such as EG before being measured by the characteristic measuring section 33 to a predetermined temperature. As described above, the depolymerized material such as EG in the depolymerized material flow section 32 can flow in either the first direction or the second direction through the direction switching section 35, so the cooling section 36 preferably includes a first cooling section 361 on the one end 321 side of the characteristic measuring section 33 and a second cooling section 362 on the other end 322 side of the characteristic measuring section 33.

[0073] In addition, a heating unit for heating the depolymerized material such as EG to a predetermined temperature may be provided instead of the cooling unit 36. However, generally, the operating temperature of the components such as sensors constituting the characteristic measuring unit 33 is relatively low (e.g., below 150°C), and therefore it may not be possible to directly measure the depolymerized material such as EG in the tank body 31 at, for example, between 180°C and 250°C. Therefore, it is preferred that the temperature of the depolymerized material such as EG be lowered to a measurable temperature (operating temperature) of the characteristic measuring unit 33 by the cooling unit 36. Figure 4 As shown in the figure, the cooling unit 36 ​​provided before and after (or above and below) the characteristic measuring unit 33 can also cool the characteristic measuring unit 33 itself. In addition, by providing a temperature sensor (not shown) facing the characteristic measuring unit 33 and measuring the temperature of the depolymerized material such as EG, the cooling unit 36 ​​and / or the heating unit are controlled so that the measured temperature of the temperature sensor approaches the predetermined measurable temperature of the characteristic measuring unit 33.

[0074] According to the depolymerization reaction monitoring device 30 or the progress monitoring unit 37 according to the first embodiment as described above, by measuring the properties of the depolymerization material such as EG by the property measuring unit 33 in the depolymerization reaction tank 300 (depolymerization material flow section 32), the progress of the depolymerization reaction of the polyester or polymer obtained by dissolving the depolymerized product such as BHET as a product in the depolymerization material such as EG as a reactant or catalyst can be effectively grasped. Since it is not necessary to collect the depolymerization material such as EG as a measurement object from the depolymerization reaction tank 300 (depolymerization material flow section 32), the progress of the depolymerization reaction can be grasped in real time.

[0075] Figure 6 A second embodiment of the depolymerization reaction monitoring device 30 according to the present invention is shown. Figure 4 The same structures as in the first embodiment are marked with the same symbols, and repeated descriptions are omitted.

[0076] The depolymerization material circulation section 32 is provided with a depolymerization material diluting section 38 for further adding a depolymerization material such as EG to the depolymerization material circulation section 32 to dilute the depolymerization material. The depolymerization material diluting section 38 includes a dilution depolymerization material supply section 381 for supplying a depolymerization material such as EG for dilution, a dilution pipe 382 for connecting the dilution depolymerization material supply section 381 and the depolymerization material circulation section 32, a dilution valve 383 provided in the dilution pipe 382, ​​a first valve 384 provided in the depolymerization material circulation section 32, which is closer to the one end 321 side than the connection section connected to the dilution pipe 382 and the characteristic measuring section 33 and closer to the other end 322 side than the first cooling section 361, and a second valve 385 provided in the depolymerization material circulation section 32, which is closer to the other end 322 side than the connection section connected to the dilution pipe 382 and the characteristic measuring section 33 and closer to the one end 321 side than the second cooling section 362.

[0077] Figure 72 shows an example in which the depolymerized material is diluted by the depolymerized material diluting unit 38. Figure 5A As shown in FIG. 1 , there is a correlation such as a proportional relationship between the refractive index of the depolymerized material such as EG in which the depolymerized product such as BHET is dissolved and the concentration of the depolymerized product such as BHET in the depolymerized material such as EG. Figure 7 As shown in FIG. 1 (before dilution), this correlation does not hold when the concentration of BHET or the like exceeds the predetermined value A. Therefore, the progress monitoring unit 37 may not be able to accurately grasp the concentration of BHET or the like based on the refractive index measured by the characteristic measuring unit 33 .

[0078] Therefore, the depolymerization material diluting section 38 additionally supplies the depolymerization material such as EG from the diluted depolymerization material supplying section 381 to the high concentration BHET solution such as the one that destroys the linearity of the measurement in the characteristic measuring section 33. As a result, the concentration of the depolymerized product such as BHET in the depolymerization material flowing section 32 (between the first valve 384 and the second valve 385) decreases, as shown in FIG. Figure 7 As shown in (after dilution), the correlation or linearity can be maintained even in the high concentration region. That is, by reducing the concentration of depolymerized products such as BHET in the depolymerized material flow section 32, the refractive index measured by the characteristic measurement section 33 converges to Figure 7 In addition, the progress monitoring unit 37 can accurately grasp the original (undiluted) concentration of BHET, etc. in the tank body 31 based on the refractive index normally measured by the characteristic measuring unit 33 within the linear range and the amount of EG, etc. used for dilution by the dilution and depolymerization material supply unit 381 (adjusted by the dilution valve 383 as described later). Figure 7 concentration on the “after dilution” line in the equation).

[0079] In addition, the diluted depolymerization material supply unit 381 may also supply Figure 1 The depolymerized EG or the like recovered by the depolymerized material supply unit 310, the depolymerization reaction tank 300, the polymerization reaction tank 400, the by-product removal device 500, etc. in the chemical recovery device 100 can be used as the diluted depolymerized material. Alternatively, the depolymerized EG or the like that is not used in the main process of the chemical recovery device 100 such as the depolymerized material supply unit 310, the depolymerization reaction tank 300, the polymerization reaction tank 400, the by-product removal device 500, etc. can also be used as the diluted depolymerized material. The diluted depolymerized material can be any material as long as it is a material containing the depolymerized EG or the like as a main component, and can contain impurities. Such impurities preferably do not have an adverse effect on the depolymerization reaction and / or repolymerization reaction, the characteristic measurement of the characteristic measurement unit 33, the progress monitoring of the progress monitoring unit 37, the by-product removal of the by-product removal device 500, etc.

[0080] In order to improve the measurement accuracy of the characteristic measuring unit 33 when using the depolymerized material diluting unit 38 as described above, various valves such as the dilution valve 383, the first valve 384, and the second valve 385 are provided. Figure 8The flowchart of the specific measurement sequence example shown in the figure explains the opening and closing operation of each valve. "S" in the description of the flowchart represents a step or a process.

[0081] In S1 at the start of measurement, the first valve 384 and the second valve 385 are in an open state, and the dilution valve 383 is in a closed state. In S2, the backwash pump and the like constituting the direction switching unit 35 are operated, and the depolymerized material such as EG to be measured is input from the tank body 31 to the depolymerized material flow unit 32. At this time, as described above, the first cooling unit 361 and / or the second cooling unit 362 cool the input depolymerized material such as EG to a predetermined measurable temperature of the characteristic measuring unit 33. As a result, the depolymerized material such as EG cooled by the first cooling unit 361 and / or the second cooling unit 362 enters the space between the first valve 384 and the second valve 385 which are in an open state in S1. In S3, the first valve 384 and the second valve 385 are switched to a closed state. As a result, a closed space is temporarily formed between the first valve 384 and the second valve 385, and the total amount of BHET and the like in the closed space can be determined.

[0082] In S4, the characteristic measuring unit 33 performs a primary measurement of the refractive index of the depolymerized material such as EG in the closed space formed in S3. In S5, it is determined whether the refractive index measured in S4 exceeds Figure 7 The saturation threshold B is shown. If the determination in S5 is "No", the refractive index measured in S4 is within the linear range below the saturation threshold B, and therefore is directly adopted as the measurement result of the characteristic measurement unit 33 in S6. In S7, the progress monitoring unit 37 calculates the concentration of the depolymer such as BHET based on the measurement result of the refractive index obtained in S6.

[0083] If it is determined as "yes" in S5, the refractive index measured in S4 is out of the linear range of the characteristic measuring section 33, so even if it proceeds directly to S6 and S7, it is impossible to obtain the accurate concentration of the depolymerized product such as BHET. Therefore, in S8, the dilution valve 383 is switched to an open state. In the subsequent S8 (2), the second valve 385 is switched to an open state in order to introduce the EG for dilution into the characteristic measuring section 33. In S9, the backwash pump and the like constituting the direction switching section 35 are operated, and the EG for dilution is supplied from the dilution depolymerized material supply section 381 to the space between the first valve 384 and the second valve 385 through the dilution valve 383 in the open state. In S9, the amount of EG for dilution is measured by a flow sensor (not shown) provided in the dilution valve 383 and the like. The dilution valve 383 is switched to the closed state in S10 , and the second valve 385 is switched to the closed state in S10 ( 2 ), thereby forming a closed space between the first valve 384 and the second valve 385 again.

[0084] In S11, the characteristic measuring unit 33 performs a secondary measurement of the refractive index of the depolymerized material such as EG in the closed space formed in S3 and S10 (2), and returns to S5. In the case of "No" in S5, the refractive index of the diluted EG measured in S11 is within the linear range below the saturation threshold B, so it is directly adopted as the measurement result of the characteristic measuring unit 33 in S6. In S7, the progress monitoring unit 37 calculates the concentration ( ) of BHET etc. in the original (undiluted) tank body 31 based on the secondary measurement result of the refractive index within the linear range obtained in S11 and the amount of EG etc. used for dilution in S9. Figure 7 That is, as described above, the amount of depolymerization material such as EG entering the closed space (space divided by three valves) formed in S3 from the tank body 31 and the diluted depolymerization material supply unit 381 can be controlled by the dilution valve 383, the first valve 384 and the second valve 385, so that the progress monitoring unit 37 can calculate the concentration of BHET and the like in the tank body 31 while grasping the quantitative effect of the dilution by the depolymerization material dilution unit 38.

[0085] If it is determined as "yes" in S5, the process proceeds to S8 to S11 again, and the dilution in S9 and the secondary measurement in S11 are repeated until it is determined as "no" in S5, that is, until the secondary measurement result of the refractive index in S11 converges to a linear range below the saturation threshold value B. In S7 when the measurement is completed, the first valve 384, the second valve 385, and the dilution valve 383 are in a closed state.

[0086] Not only the amount of the dilution EG etc. supplied by the dilution depolymerization material supply unit 381 can be controlled by the dilution valve 383 etc., but also the temperature thereof can be controlled. For example, by supplying the dilution EG etc. whose temperature is controlled in S9 to the closed space formed in S3, the EG etc. in the closed space can be cooled to a predetermined measurable temperature of the characteristic measuring unit 33. In this way, at least a part of the functions of the cooling unit 36 ​​can be realized by the dilution EG etc. supplied by the dilution depolymerization material supply unit 381. In this case, it is not necessary to provide a cooling valve 383. Figure 6 At least a portion of the first cooling section 361 and the second cooling section 362.

[0087] Fig. 9 A third embodiment of the depolymerization reaction monitoring device 30 according to the present invention is shown. Figure 4 The first embodiment and / or Figure 6 The same structures as in the second embodiment are marked with the same symbols, and repeated descriptions are omitted.

[0088] The depolymerization material circulation section 32 is provided with an extraction section 39 capable of extracting a specified amount of depolymerization material such as EG circulating therein. The extraction section 39 includes, for example, a syringe pump 391 and an extraction valve 392. The syringe pump 391 extracts, inputs, or discharges depolymerization material such as EG according to the position of a movable piston contained therein. The extraction valve 392 is provided between the main body of the tubular depolymerization material circulation section 32 and the syringe pump 391. In addition, the extraction section 39 may include other types of pumps instead of the syringe pump 391. For example, a gear pump, a suction pump, a plunger pump, or a vane pump may be provided in the extraction section 39 instead of the syringe pump 391.

[0089] The characteristic measuring unit 33 is provided in the syringe pump 391. Specifically, as schematically shown in the figure, the above-mentioned optical measurement is performed through a window 333 provided in the syringe pump 391 (illustration of the light source 331 and the light receiving unit 332 is omitted). Such a characteristic measuring unit 33 measures the characteristics of the depolymerized material such as EG extracted by the extraction unit 39 (syringe pump 391).

[0090] and Figure 6 Similar to the second embodiment in the above, the depolymerization material diluting section 38 is provided in the depolymerization material circulation section 32 for further adding depolymerization material such as EG to the depolymerization material extracted by the extraction section 39 (syringe pump 391) to dilute the depolymerization material. The property measuring section 33 measures the property of the depolymerization material such as EG diluted by the depolymerization material diluting section 38.

[0091] Fig.10 2 is a flowchart of a specific measurement sequence example. Figure 8 The same steps or processes are marked with the same symbols, and repeated descriptions are omitted.

[0092] In S1 at the start of measurement, the extraction valve 392 is in an open state and the dilution valve 383 is in a closed state. In S2, the backwash pump and the like constituting the direction switching unit 35 are operated, and the depolymerized material such as EG to be measured is input from the tank body 31 to the depolymerized material circulation unit 32. In S12, the extraction unit 39 extracts (extracts once) a specified amount (first specified amount) of the depolymerized material such as EG input to the depolymerized material circulation unit 32 in S2. In S3, the extraction valve 392 is switched to a closed state. As a result, the first specified amount of the depolymerized material such as EG is secured in the extraction unit 39 (syringe pump 391).

[0093] In S4, the characteristic measuring unit 33 measures the refractive index of the first designated amount of the depolymerized material such as EG secured in the extraction unit 39 (syringe pump 391) in S3. In S5, it is determined whether the refractive index measured in S4 exceeds Figure 7The saturation threshold B is shown. If the determination in S5 is "No", the refractive index measured in S4 is within the linear range below the saturation threshold B, and therefore is directly adopted as the measurement result of the characteristic measurement unit 33 in S6. In S7, the progress monitoring unit 37 calculates the concentration of the depolymer such as BHET based on the measurement result of the refractive index obtained in S6.

[0094] If it is determined to be "yes" in S5, the refractive index measured in S4 is out of the linear range of the characteristic measuring unit 33, so even if it directly proceeds to S6 and S7, it is impossible to obtain the accurate concentration of the depolymerized product such as BHET. Therefore, in S8, the dilution valve 383 is switched to an open state. In S13, the extraction unit 39 extracts (secondarily extracts) a specified amount (second specified amount) of EG for dilution from the dilution depolymerization material supply unit 381 through the dilution valve 383 in the open state. And, in S9, the EG in the extraction unit 39 (syringe pump 391) is diluted by the EG for dilution extracted in S13. In S10, the dilution valve 383 is switched to a closed state. As a result, in addition to the first specified amount of EG and other depolymerized materials (BHET and other depolymerized products dissolved) extracted once in S12, the second specified amount of EG and other depolymerized materials (BHET and other depolymerized products not dissolved) extracted for the second time in S13 is ensured in the extraction section 39 (syringe pump 391).

[0095] In S11, the characteristic measuring unit 33 performs a secondary measurement of the refractive index of the first designated amount and the second designated amount of the depolymerized material such as EG secured in the extraction unit 39 (syringe pump 391) in S3 and S10, and returns to S5. In a case where the determination in S5 is "No", the refractive index of the diluted EG measured in S11 converges within the linear range below the saturation threshold value B, and therefore is directly adopted as the measurement result of the characteristic measuring unit 33 in S6. In S7, the progress monitoring unit 37 calculates the concentration ( ) of BHET etc. in the original (undiluted) tank body 31 based on the secondary measurement result of the refractive index within the linear range obtained in S11, the first designated amount extracted once in S12 (obtained from the syringe pump 391 and the extraction valve 392), and the second designated amount extracted twice in S13 (obtained from the syringe pump 391 and the dilution valve 383). Figure 7 That is, as described above, the amount of depolymerization material such as EG entering the extraction section 39 (syringe pump 391) from the tank body 31 (or the depolymerization material circulation section 32) and the diluted depolymerization material supply section 381 can be controlled by the syringe pump 391, the extraction valve 392 and the dilution valve 383, so that the progress monitoring section 37 can calculate the concentration of BHET and the like in the tank body 31 while grasping the quantitative effect of the dilution by the depolymerization material dilution section 38.

[0096] If the determination result in S5 is "yes", the process proceeds to S8 to S11 again, and the secondary extraction in S13, the dilution in S9, and the secondary measurement in S11 are repeated until the determination result in S5 is "no", that is, until the secondary measurement result of the refractive index performed in S11 converges to a linear range below the saturation threshold value B. In S7 when the measurement is completed, the extraction valve 392 and the dilution valve 383 are closed.

[0097] The present invention has been described above based on the embodiments. It is obvious to those skilled in the art that various modifications can be implemented in the combination of the constituent elements or the processes in the embodiments described as examples, and such modifications are included in the scope of the present invention.

[0098] In addition, the configuration, function, 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. As hardware resources, for example, processors, ROM, RAM, and various integrated circuits can be used. As software resources, for example, programs such as operating systems and application programs can be used.

[0099] Industrial Applicability

[0100] The present invention relates to a depolymerization reaction monitoring device and the like.

[0101] Explanation of symbols

[0102] 1-injection molding machine, 30-depolymerization reaction monitoring device, 31-tank body, 32-depolymerization material circulation part, 33-characteristic measuring part, 34-intrusion blocking part, 35-direction switching part, 36-cooling part, 37-progress monitoring part, 38-depolymerization material dilution part, 39-extraction part, 100-chemical recovery device, 300-depolymerization reaction tank, 321-one end, 322-other end, 331-light source, 332-light receiving part, 333-window, 341-first filter, 342-second filter, 361-first cooling part, 362-second cooling part, 381-dilution depolymerization material supply part, 382-dilution tube, 383-dilution valve, 384-first valve, 385-second valve, 391-injection pump, 392-extraction valve.

Claims

1. A depolymerization reaction monitoring device, comprising: a depolymerization reaction tank for initiating a depolymerization reaction of decomposing the polyester into depolymerized products by a depolymerization material; a property measuring unit for measuring the property of the depolymerized material in which the depolymerized product is dissolved in the depolymerization reaction tank; and The progress monitoring unit monitors the progress of the depolymerization reaction based on the property of the depolymerization material measured by the property measuring unit.

2. The depolymerization reaction monitoring device according to claim 1, wherein: The depolymerization reaction tank comprises a tank body for initiating the depolymerization reaction and a depolymerization material flow section for flowing the depolymerization material between the tank body and the tank body. The property measuring unit measures the property of the depolymerized material in the depolymerized material flowing section.

3. The depolymerization reaction monitoring device according to claim 2, wherein: One end and the other end of the depolymerized material flow portion are connected to different locations of the tank body.

4. The depolymerization reaction monitoring device according to claim 3, wherein: Intrusion prevention portions for preventing insoluble substances insoluble in the depolymerization material from intruding from the tank body into the depolymerization material passage portion are provided at one end side and the other end side of the depolymerization material passage portion.

5. The depolymerization reaction monitoring device according to claim 4, comprising: The direction switching section is capable of switching the flow direction of the depolymerized material in the depolymerized material flowing section between a first direction from the one end toward the other end and a second direction from the other end toward the one end.

6. The depolymerization reaction monitoring device according to any one of claims 2 to 5, comprising: The depolymerization material diluting section further adds the depolymerization material to the depolymerization material in the depolymerization material flowing section to dilute the depolymerization material.

7. The depolymerization reaction monitoring device according to any one of claims 2 to 5, wherein: The depolymerized material circulation unit includes an extraction unit capable of extracting a predetermined amount of the depolymerized material circulating therein. The property measuring unit measures the property of the depolymerized material extracted by the extraction unit.

8. The depolymerization reaction monitoring device according to claim 7, comprising: a depolymerization material diluting section for further adding the depolymerization material to the depolymerization material extracted by the extraction section to dilute the depolymerization material, The property measuring unit measures the property of the depolymerized material diluted by the depolymerized material diluting unit.

9. The depolymerization reaction monitoring device according to any one of claims 2 to 5, comprising: A cooling unit cools the depolymerized material in the depolymerized material flowing unit.

10. The depolymerization reaction monitoring device according to any one of claims 1 to 5, wherein: The property measuring unit measures the optical property of the depolymerized material in which the depolymerized product is dissolved in the depolymerization reaction tank.

11. The depolymerization reaction monitoring device according to claim 10, wherein: The optical property is the refractive index.

12. The depolymerization reaction monitoring device according to any one of claims 1 to 5, wherein: The property measurement unit measures the electrical property of the depolymerized material in which the depolymerized product is dissolved in the depolymerization reaction tank.

13. The depolymerization reaction monitoring device according to any one of claims 1 to 5, wherein: The polyester is polyethylene terephthalate, The depolymerization material is ethylene glycol, The depolymerized product is bis(2-hydroxyethyl)terephthalate.

14. A method for monitoring a depolymerization reaction, comprising: A step of initiating a depolymerization reaction in a depolymerization reaction tank to decompose the polyester into depolymerized products by a depolymerization material; The step of measuring the properties of the depolymerized material in which the depolymerized product is dissolved in the depolymerization reaction tank; and The step of monitoring the progress of the depolymerization reaction based on the measured properties of the depolymerized material.

15. A depolymerization reaction monitoring program, which causes a computer to execute: A step of initiating a depolymerization reaction in the depolymerization reaction tank to decompose the polyester into depolymerized products by a depolymerization material; The step of measuring the characteristics of the depolymerized material in which the depolymerized product is dissolved in the depolymerization reaction tank; and The step of monitoring the progress of the depolymerization reaction based on the measured properties of the depolymerized material.

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