Polymerization system, method for producing polymer, and chemical recycling system

Abstract

This polymerization system 700 comprises: a polymerization reaction unit 710 for synthesizing a depolymerization product of a polyester into a polymer by a polymerization reaction; and a terephthalic acid supply unit 730 for supplying terephthalic acid to the polymerization reaction unit 710 after the polymerization reaction has progressed to a predetermined degree or more and before the polymerization reaction is completed. The polymerization system is provided with a polymerization reaction progress rate detection unit 720 for detecting the progress rate of the polymerization reaction, and the terephthalic acid supply unit 730 supplies terephthalic acid to the polymerization reaction unit 710 after the progress rate becomes equal to or higher than a predetermined progress rate that is larger than 0%, and before the progress rate reaches 100%.

Description

Polymerization system, polymer manufacturing method, chemical recycling system

[0001] The present disclosure relates to polymerization systems and the like.

[0002] Patent Document 1 discloses a method for producing PET (polyethylene terephthalate) by polymerization of bis(2-hydroxyethyl) terephthalate (BHET). Terephthalic acid (TPA) is added to remove ethylene glycol (EG), a by-product produced by the polymerization of BHET (see, for example, paragraphs 0053 to 0054).

[0003] JP 2004-231855 A JP 2022-27158 A

[0004] As described above, the addition of TPA in the polymerization reaction of BHET (production of PET) is known, but the present inventors have independently discovered a more effective method for using TPA.

[0005] The present disclosure has been made in view of the above circumstances, and aims to provide a polymerization system and the like that can efficiently proceed with a polymerization reaction using terephthalic acid.

[0006] In order to solve the above problems, a polymerization system according to an embodiment of the present disclosure includes a polymerization reaction section that synthesizes a depolymerized polyester into a polymer through a polymerization reaction, and a terephthalic acid supply section that supplies terephthalic acid to the polymerization reaction section after the polymerization reaction has progressed to a predetermined extent or more but before the polymerization reaction is completed.

[0007] In this embodiment, terephthalic acid is not supplied simultaneously with the start of the polymerization reaction, but is supplied after the polymerization reaction has progressed to a predetermined extent or more (and before the polymerization reaction is completed, i.e., before the polymerization end point is reached). As will be described in detail later, it has been found that supplying terephthalic acid at a stage when the polymerization reaction has not yet progressed sufficiently inhibits the progress of the polymerization reaction. Therefore, in this embodiment, terephthalic acid is supplied at an "intermediate" stage after the polymerization reaction has progressed to a predetermined extent or more, thereby accelerating the polymerization reaction toward completion.

[0008] Another aspect of the present disclosure is a method for producing a polymer, which includes synthesizing a depolymerized polyester into a polymer by a polymerization reaction in a polymerization reaction section, and supplying terephthalic acid to the polymerization reaction section after the polymerization reaction has progressed to a predetermined extent or more but before the polymerization reaction is completed.

[0009] Yet another aspect of the present disclosure is a chemical recycling system including a depolymerization reaction tank that decomposes a polyester polymer into depolymers by a depolymerization reaction, a polymerization reaction unit that synthesizes the depolymers into polymers by a polymerization reaction, and a terephthalic acid supply unit that supplies terephthalic acid to the polymerization reaction unit after the polymerization reaction has progressed to a predetermined extent or more but before the polymerization reaction is completed.

[0010] Any combination of the above components, or any conversion of these expressions into methods, devices, systems, recording media, computer programs, etc., are also encompassed within the present disclosure.

[0011] According to the present disclosure, the polymerization reaction can be efficiently carried out using terephthalic acid.

[0012] Schematic diagram of the configuration of a chemical recycling molding system. Schematic diagram of the polymerization reaction and depolymerization reaction of PET. A modified example of a by-product removal device is shown. A simplified schematic functional block diagram of the chemical recycling molding system of FIG. 1. Schematic diagram of the adhesive function of terephthalic acid. Transition data of the BHET conversion rate over time depending on whether or not TPA is added and the timing of addition. Transition data of the BHET conversion rate over time depending on whether or not TPA is added and the amount added. Chemical properties of the final product in the experimental example of FIG. 7 are shown.

[0013] Hereinafter, with reference to the drawings, a detailed description of embodiments of the present disclosure (hereinafter also referred to as "embodiments") will be given. In the description and / or drawings, identical or equivalent components, members, processes, etc. will be designated by the same reference numerals, and redundant description will be omitted. The scale and shape of each part shown in the drawings are set for convenience to simplify the description and should not be interpreted as limiting unless otherwise specified. The embodiments are merely examples and do not limit the scope of the present disclosure in any way. Not all features and combinations thereof presented in the embodiments are necessarily essential to the present disclosure. For convenience, the embodiments are presented broken down into components for each function and / or functional group that realizes the features. However, one component in an embodiment may actually be realized by a combination of multiple separate components, or multiple components in an embodiment may actually be realized by a single integrated component. Furthermore, although multiple embodiments and variants may be disclosed in parallel, any components of each embodiment and / or each variant may be combined in any manner as long as they do not interfere with each other's functions.

[0014] 1 schematically illustrates the configuration of a chemical recycling molding system as a chemical recycling system to which a polymerization system according to an embodiment of the present disclosure can be applied. The chemical recycling molding system includes a chemical recycling apparatus 100 and an injection molding machine 1. The chemical recycling apparatus 100 includes a polymer adjustment apparatus 200, a depolymerization reaction tank 300, a polymerization reaction tank 400, a by-product removal apparatus 500, and a polymer supply unit 600. In this embodiment, all or any part of the polymerization reaction tank 400, the by-product removal apparatus 500, and the polymer supply unit 600 constitute the polymerization system or polymerization reaction unit according to the present disclosure.

[0015] Any number of injection molding machines 1 (two are shown schematically in FIG. 1 ), polymer adjustment devices 200, depolymerization reaction tanks 300, polymerization reaction tanks 400, by-product removal devices 500, and polymer supply units 600 may be installed. In particular, by increasing the number of injection molding machines 1 and polymerization reaction tanks 400, which typically have slower processing speeds or reaction rates than other processing units, compared to other processing units, it is possible to prevent these processing units from becoming serious bottlenecks and improve processing performance.

[0016] The polymer preparation apparatus 200 prepares a polymer such as PET constituting a first molded article such as a PET bottle for the subsequent depolymerization reaction tank 300. Specifically, the polymer preparation apparatus 200 subjects the first molded article such as a PET bottle to treatments such as pulverization, heat melting, and mixing, thereby adjusting 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 article may be any molded article other than a bottle, such as a sheet, film, or fiber. The polymer constituting the first molded article may be any polymer or polymers other than PET, such as polyester (including PET), polyamide, or polyurethane.

[0017] The depolymerization reaction tank 300 decomposes the polymer, such as PET, prepared by the polymer preparation apparatus 200 into depolymers through a depolymerization reaction. When the polymer supplied from the polymer preparation apparatus 200 is PET, the intermediate BHET is obtained as a depolymer through the depolymerization reaction in the depolymerization reaction tank 300. The depolymer obtained in the depolymerization reaction tank 300 may contain a monomer or monomers of the polymer. When the polymer is PET, examples of the monomer include ethylene glycol, terephthalic acid, dimethyl terephthalate, and ethylene terephthalate.

[0018] As shown schematically 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 a depolymerization agent supply unit 310 ( FIG. 1 ) to the depolymerization reaction tank 300, to obtain BHET as a depolymerized product. Instead of or in addition to the depolymerization agent supply unit 310, EG may be supplied from the polymer preparation apparatus 200. To promote this 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 adjacent to the depolymerization reaction tank 300. The temperature suitable for the depolymerization reaction of PET to BHET in FIG. 2 is between 180° C. and 250° C., preferably between 230° C. and 245° C., and more preferably between 235° C. and 240° C. 2 is suitable for a depolymerization reaction of PET to BHET between atmospheric 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. The pressure unit MPa, G is gauge pressure. The pressure inside depolymerization reaction tank 300 is adjusted by a pump (not shown) or the like that is provided in addition to depolymerization reaction tank 300.

[0019] The viscosity of the fluid in the depolymerization reaction tank 300, where 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, which will be described later, where PET, which has a larger molecular weight, is produced. Therefore, 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.

[0020] Foreign matter removal devices 340, 350, and 360 are provided downstream of the depolymerization reaction tank 300 to remove foreign matter from the fluid containing BHET as the main component of the depolymerization. The foreign resin removal device 340 removes resins other than the target resin, such as PET, and / or depolymerized resins thereof using 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 using the principles of ion exchange or the like. A buffer tank 370 may be provided downstream of the foreign matter removal devices 340, 350, and 360 to temporarily store the fluid containing BHET and other components after the foreign matter has been removed before supplying it to the polymerization reaction tank 400.

[0021] The buffer tank 370 may be provided with a first preheater 371 that heats or keeps warm the depolymerized polymer (a fluid mainly composed of BHET, etc.) before it is supplied to the downstream polymerization reaction tank 400. The first preheater 371 may maintain the depolymerized polymer at a temperature (between 180°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 the polymerization reaction similar to that of the heater 410 provided in the polymerization reaction tank 400 described below. In this way, by providing the buffer tank 370 equipped with a preheating mechanism (first preheater 371) as needed upstream of the polymerization reaction tank 400, the depolymerized polymer can be stored at an appropriate temperature while being fed into the polymerization reaction tank 400, which typically has a slower processing speed or reaction rate than other processing units such as the depolymerization reaction tank 300 and the by-product removal device 500 described below. 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 running out of resin) while supplying appropriate amounts of reactants in a timely manner to each processing section, such as the depolymerization reaction tank 300, the polymerization reaction tank 400, the by-product removal device 500, and the polymer supply section 600. Note that the preheating mechanism such as the first preheater 371 is not limited to being provided in the buffer tank 370, but may be provided in any location between the depolymerization reaction tank 300 and the polymerization reaction tank 400 (for example, in the foreign matter removal devices 340, 350, 360) in any manner.

[0022] The polymerization reactor 400 polymerizes depolymerized materials such as BHET 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 a polymer through a polymerization reaction. When the depolymerized material produced in the depolymerization reactor 300 is BHET, the polymer PET is re-obtained through a polymerization reaction in the polymerization reactor 400. The polymerization reactor 400, to which the depolymerized material such as BHET is supplied and the polymerization reaction is initiated, constitutes a polymerization reaction section according to the present disclosure, which synthesizes a depolymerized material (such as BHET) of polyester (such as PET) into a polymer (such as PET) through a polymerization reaction.

[0023] As schematically shown in FIG. 2 , the polymerization reaction (400) of BHET as a depolymerization product produces PET as a main polymer product and EG as a by-product. This EG may be recycled to the depolymerization agent supply unit 310 and used in the depolymerization reaction of PET in the depolymerization reaction tank 300. In this case, the EG produced in the polymerization reaction tank 400 can be reused on site (in the depolymerization reaction tank 300) without being wasted, thereby improving the operating efficiency of the chemical recycling apparatus 100. In particular, the amount of EG purchased or procured for the depolymerization reaction of PET in the depolymerization reaction tank 300 can be significantly reduced, leading to a reduction in the operating costs of the chemical recycling apparatus 100.

[0024] To promote the above-described polymerization reaction, the interior of the polymerization reactor 400 is maintained at a temperature suitable for the polymerization reaction by a heater 410 ( FIG. 1 ) or a warmer attached to the polymerization reactor 400 as a second heater. 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. The polymerization heating temperature by the heater 410 attached to the polymerization reactor 400 is higher than the depolymerization heating temperature by the heater 320 attached to the depolymerization reactor 300. The polymerization reactor 400 produces PET with a high molecular weight and a high melting point. By maintaining the temperature higher than that of the depolymerization reactor 300, which produces BHET with a low molecular weight and a low melting point, the PET, the main product of the polymerization reactor 400, is maintained in a molten state. As will be described later, it is preferable that at least the final stage of the polymerization reaction of BHET to PET in Fig. 2 be carried out under vacuum or reduced pressure. For this reason, a vacuum pump or the like (not shown) is provided as a pressure reducing unit in the polymerization reaction vessel 400.

[0025] The viscosity of the fluid in the polymerization reaction tank 400, where PET having a high molecular weight is produced, is higher than the viscosity of the fluid in the depolymerization reaction tank 300, where BHET having a lower molecular weight than PET, which is a polymer, is produced. Therefore, 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.

[0026] The IV (intrinsic viscosity) value or inherent viscosity is known as a value correlated with the degree of polymerization of polymers such as PET. The IV value (dL / g) is also used as an indicator of polymer applications. For PET, an IV value of approximately 0.72 or higher is suitable for bottles, an IV value of approximately 0.65 or higher is suitable for sheets and films, and an IV value of approximately 0.58 or higher is suitable for fibers. The objective of this embodiment is to ultimately obtain PET with an IV value suitable for bottles and sheets. As described below, the IV value is also increased in the by-product removal device 500 downstream of the polymerization reactor 400, so the IV value of the PET synthesized in the polymerization reactor 400 may be relatively low. Specifically, the IV value of the PET synthesized in the polymerization reactor 400 is between 0.2 and 0.7, preferably between 0.3 and 0.7, and more preferably between 0.3 and 0.55. However, as described below, it has been confirmed that when the amount of TPA added during the polymerization reaction exceeds the amount (equivalent) required for bonding or adhesion between PET oligomers, the IV value is low despite a high conversion rate. Therefore, in the context of the present embodiment described below, the conversion rate and the IV value are considered to have no correlation.

[0027] 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 downstream by-product removal device 500 and / or polymer supply unit 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 downstream by-product removal device 500 and / or polymer supply unit 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 adjacent 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 adjacent to the by-product removal device 500 described below, or may maintain the polymer at a temperature (between 250°C and 290°C) similar to that of the heater 620 provided adjacent to the polymer supply unit 600 described below.

[0028] In this way, by providing a buffer tank 430 equipped with a preheating mechanism (second preheater 431) as needed upstream of the by-product removal apparatus 500 and / or the polymer supply unit 600, polymers waiting to be introduced into the by-product removal apparatus 500 and / or the polymer supply unit 600 can be stored while being maintained 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 appropriately supplying appropriate amounts of reactants to each processing unit, such as the depolymerization reaction tank 300, the polymerization reaction tank 400, the by-product removal apparatus 500, and the polymer supply unit 600, in a timely manner (without running out of resin). Note that a preheating mechanism such as the second preheater 431 is not limited to the buffer tank 430, but can be provided in any manner at any location between the polymerization reaction tank 400 and the by-product removal apparatus 500 and / or at any location between the by-product removal apparatus 500 and the polymer supply unit 600.

[0029] A by-product removal device 500 is provided downstream of the polymerization reaction tank 400 (and upstream of the polymer supply section 600, which will be described later), through which PET (main product) and EG (by-product) produced by the polymerization reaction in the polymerization reaction tank 400 are passed, and which removes the EG as a by-product. The by-product removal device 500 in the illustrated example includes a number of linear members 510 extending from above to below. The increased surface area provided by the number of linear members 510 promotes the volatilization of EG adhering to the surface of each linear member 510, thereby effectively separating and removing the EG from the highly viscous PET.

[0030] This EG may be recycled to the depolymerization agent supply unit 310 and used in the depolymerization reaction of PET in the depolymerization reaction tank 300. The EG separated and removed in the by-product removal device 500 can be reused on site (in the depolymerization reaction tank 300) without being wasted, thereby improving the operating efficiency of the chemical recycling apparatus 100. In particular, the amount of EG purchased or procured for the PET depolymerization reaction in the depolymerization reaction tank 300 can be significantly reduced, leading to a reduction in the operating costs of the chemical recycling apparatus 100.

[0031] Furthermore, PET with a relatively low degree of polymerization (or IV value) and BHET that remains unreacted in the polymerization reactor 400 also adhere to the surface of each linear member 510, allowing the large surface area to effectively promote a polymerization reaction similar to that in the polymerization reactor 400. Therefore, the IV value of the PET as the main product is increased by passing through the by-product removal device 500. Specifically, the IV value of the PET after passing through the by-product removal device 500 is 0.7 or higher, preferably 0.8 or higher, and more preferably 0.85 or higher. Thus, the by-product removal device 500, which is provided downstream of the polymerization reactor 400 and removes by-products (such as EG) generated by the polymerization reaction, continues the polymerization reaction initiated in the polymerization reactor 400, and thus constitutes a polymerization reaction section according to the present disclosure, similar to the polymerization reactor 400.

[0032] To promote this polymerization reaction, the inside of the by-product removal apparatus 500 can be maintained at a temperature suitable for the polymerization reaction by a heater 520 ( FIG. 1 ) or a warmer attached to the by-product removal apparatus 500 as a second heater. 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 attached to the by-product removal apparatus 500 is preferably higher than the polymerization heating temperature by the heater 410 attached to the polymerization reaction tank 400. Since the polymerization reaction proceeds more rapidly in the by-product removal apparatus 500 than in the polymerization reaction tank 400, the molecular weight of the PET polymer increases and the melting point increases. Therefore, by maintaining the inside of the by-product removal apparatus 500 at a higher temperature than in the polymerization reaction tank 400, the PET product of the by-product removal apparatus 500 can be maintained in a molten state. A heater or a warmer may be provided as a second heater around the piping between the polymerization reaction tank 400 and the by-product removal apparatus 500, which heats or keeps the temperature at least to the polymerization heating temperature of the heater 410 provided next to the polymerization reaction tank 400. The polymerization reaction in the by-product removal apparatus 500 is preferably carried out in a vacuum state, similar to the polymerization reaction in the polymerization reaction tank 400. For this reason, the by-product removal apparatus 500 is provided with a vacuum pump or the like (not shown) as a decompression section. By creating a vacuum state (decompressed state) inside the by-product removal apparatus 500, EG as a by-product can be efficiently removed.

[0033] The configuration of the by-product removal apparatus 500 is not limited to the "vertical" type shown in FIG. 1 . For example, a "horizontal two-axis" agitator as shown in FIG. 3 may be used as the by-product removal apparatus 500. This agitator includes two rotating shafts extending perpendicular to the plane of FIG. 3 and two agitating blades that rotate around the two rotating shafts to agitate the PET and EG as the agitation targets. Agitation by the two agitating blades promotes the evaporation of EG, thereby effectively separating and removing EG from the highly viscous PET. Details of the agitator shown in FIG. 3 are disclosed in Japanese Patent No. 2925599, which is incorporated herein by reference.

[0034] The polymer supply section 600, which constitutes the final stage or output stage of the polymerization reaction section according to the present disclosure and includes the polymerization reaction tank 400 and the by-product removal device 500, supplies a 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 that molds a second molded product such as a PET bottle. The polymer supply section 600 is equipped with a transfer pump 610, such as a gear pump or a screw pump, that is suitable for supplying the PET, in a molten state, to the injection molding machine 1, from which EG as a by-product has been removed in the by-product removal device 500 and which has high purity and high viscosity (i.e., high degree of polymerization or high IV value).

[0035] The polymer supply section 600 may be provided with a heater 620 or a warmer as a first heater that heats or keeps warm the polymer such as PET transferred to the injection molding machine 1 by the transfer 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 section 600 is preferably higher than the second heating temperature by a second heater such as the heater 410 provided adjacent to the polymerization reaction tank 400, the heater 520 provided adjacent to 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 initiated in the polymerization reaction tank 400 gradually progresses and is completed in the by-product removal device 500. As a result, the molecular weight of the polymer, such as PET, becomes larger and the melting point becomes higher in the polymer supply section 600 than in the polymerization reaction tank 400 and the by-product removal device 500. Therefore, by setting the first heating temperature in the polymer supply section 600 higher than the previous second heating temperature, the polymer, such as PET, which has a high viscosity (or a high degree of polymerization) and a high melting point, can be maintained in a molten state.

[0036] A temperature gradient may be provided so that the heating temperature increases stepwise from the polymerization reaction tank 400 to the polymer supply unit 600. For example, the heating temperature by a heater (not shown) provided between the polymerization reaction tank 400 and the by-product removal device 500 may be made higher than the heating temperature by the heater 410 provided adjacent to the polymerization reaction tank 400, the heating temperature by the heater 520 provided adjacent to the by-product removal device 500 may be made higher than the heating temperature by the heater (not shown), and the heating temperature by the heater 620 provided in the polymer supply unit 600 may be made higher than the heating temperature by the heater 520. This ensures that a polymer such as PET, whose melting point increases from the polymerization reaction tank 400 to the polymer supply unit 600, can be maintained in a molten state. Note that a heater may be provided between the polymer supply unit 600 and the injection molding machine 1 to heat or keep the polymer such as PET warm and maintain it in a molten state.

[0037] The injection molding machine 1 molds a polymer such as molten PET produced in the chemical recycling apparatus 100 into a second molded product. In this way, the injection molding machine 1 as a molding machine is connected to a polymerization reaction section in which the polymer supply section 600 is the final stage, and molds the polymer after the polymerization reaction is completed into a second molded product. The second molded product may be the same type as or different from the first molded product that is subjected to processing such as pulverization 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 recycled second molded product is lower than that of the first molded product before recycling, but the chemical recycling apparatus 100 according to this embodiment, which is equipped with mechanisms for increasing the IV value, such as the foreign matter removal devices 340, 350, 360 and the by-product removal device 500, can increase the IV value of the recycled second molded product to be higher than that of the first molded product before recycling. For example, according to this embodiment, PET fibers with a low IV value as the first molded product can be recycled into PET bottles with a high IV value as the second molded product.

[0038] The injection molding machine 1 molds a molten resin such as PET into a second molded product. An injection molding machine using a 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 Patent Application No. 2020-130985), filed on July 31, 2020. As schematically 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 is not limited to an injection molding machine, and may be any molding machine (e.g., a compression molding machine).

[0039] 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 by the polymer supply unit 600 to the injection molding machine 1. 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 than conventional methods.

[0040] 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 it is necessary to quickly achieve the polymer IV value required for the molded product (second molded product). In this embodiment, a by-product removal device 500 having the function of accelerating the polymerization reaction and increasing the IV value of the polymer is provided in addition to the polymerization reaction tank 400, so this requirement can be fully met.

[0041] In the example of Fig. 1, only one of each of the polymer adjustment apparatus 200, depolymerization reaction tank 300, polymerization reaction tank 400, by-product removal apparatus 500, polymer supply unit 600, etc. is provided, but a plurality of each may be provided. Such a plurality of treatment units can perform equivalent treatments in parallel, thereby improving the treatment performance of the treatment unit group. Furthermore, the difference in treatment speed or reaction rate between treatment units can be reduced by increasing the number of slower treatment units.

[0042] Furthermore, one or more treatment sections may accept external materials procured from a location or facility different from the chemical recycle molding system shown in FIG. 1 , instead of or in addition to materials from the preceding treatment section. For example, when multiple polymerization reaction vessels 400 are provided, some of them may be supplied with depolymerized polymer from the depolymerization reaction vessel 300, and the rest may be supplied with depolymerized polymer procured from an external source. Similarly, when multiple by-product removal devices 500 and / or polymer supply sections 600 are provided, some of them may be supplied with polymer from the polymerization reaction vessel 400, and the rest may be supplied with polymer procured from an external source. In this way, by allowing the acceptance of external materials at each stage of processing in the chemical recycle molding system, the chemical recycle molding system can be operated flexibly and efficiently.

[0043] 4 is a schematic functional block diagram that simplifies the chemical recycling molding system of FIG. 1 , and schematically illustrates details of a polymerization system 700 according to this embodiment. The polymerization system 700 of the illustrated example includes the above-described polymerization reaction section 710, a polymerization reaction progress rate detection section 720, a terephthalic acid supply section 730, and a pressure reduction section 740. Some of these functional blocks may be omitted as long as the polymerization system 700 can achieve at least some of the actions and / or effects described below.

[0044] The polymerization reaction section 710 synthesizes a polymer through a polymerization reaction from the polyester depolymerization supplied from the depolymerization reaction tank 300 or the like. As described above, the polymerization reaction section 710 includes the polymerization reaction tank 400 to which the polyester depolymerization is supplied and the polymerization reaction is initiated, and at least one of the by-product removal device 500 and / or the polymer supply section 600, which are provided downstream of the polymerization reaction tank 400 and in which the polymerization reaction continues.

[0045] In this embodiment, similar to FIG. 2, the polyester or polymer is polyethylene terephthalate (PET) and the depolymerized product is bis(2-hydroxyethyl) terephthalate (BHET). However, the present disclosure is also applicable to combinations of different polyesters or polymers and depolymerized products. For example, the polyester or polymer may be polypropylene terephthalate (PPT) and the depolymerized product may be bis(2-hydroxypropyl) terephthalate (BHPT). Alternatively, the polyester or polymer may be polybutylene terephthalate (PBT) and the depolymerized product may be bis(2-hydroxybutyl) terephthalate (BHBT).

[0046] The catalyst used in the polymerization reaction in the polymerization reaction section 710 (particularly the polymerization reaction tank 400) preferably contains at least one element (preferably a metal) from Groups 3 to 15 of the periodic table. As the metal, cobalt, antimony, germanium, and titanium are preferred, with cobalt, antimony, and germanium being more preferred, and cobalt being most preferred. The metal may be used as the catalyst in the form of an oxide, hydroxide, or acetate. The concentration of such a catalyst is preferably 0.010 mol % to 1 mol %, more preferably 0.015 mol % to 0.500 mol %, and even more preferably 0.017 mol % to 0.340 mol %, based on the amount of depolymerized polymer (e.g., BHET) supplied to the polymerization reaction section 710.

[0047] The polymerization reaction progress rate detection unit 720 detects the progress rate of the polymerization reaction in the polymerization reaction unit 710. For example, the polymerization reaction progress rate detection unit 720 preferably detects the progress rate of the polymerization reaction in the polymerization reaction tank 400, which is the main part of the polymerization reaction unit 710, but may also detect the progress rate of the polymerization reaction in the by-product removal unit 500 and / or the polymer supply unit 600, which are located downstream.

[0048] Here, the progress rate of the polymerization reaction may be defined as the ratio of the number or amount of substances bonded together as a polymer or oligomer by the polymerization reaction to the number or amount of substances of the depolymerized polymer (BHET in FIG. 2 ) that is the reactant of the polymerization reaction before the start of the polymerization reaction. For example, if 60% of the BHET, which is the raw material for the polymerization reaction to PET, is bonded together and converted into PET as a polymer or oligomer, the progress rate of the polymerization reaction is 60%. In this way, the progress rate of the polymerization reaction may be expressed as the conversion rate or conversion rate of the depolymerized polymer to a polymer (or oligomer).

[0049] The polymerization reaction progress rate detection unit 720 may detect the progress rate of the polymerization reaction by measuring by-products (EG in FIG. 2 ) generated as the polymerization reaction progresses. For example, as shown in FIG. 2 , one EG is generated for each bond between depolymerized BHETs. Therefore, the number of bonds formed between BHETs can be detected by measuring the EG. The progress rate of the polymerization reaction can be obtained by dividing the number of bonds formed by the initial number or amount of BHET. The sensor for measuring the by-products of the polymerization reaction as described above may be installed at any location within the polymerization reaction unit 710 (e.g., polymerization reaction tank 400) or on the path through which the by-products are discharged from the polymerization reaction unit 710 (e.g., the EG discharge path indicated by the dotted line in FIG. 1 ).

[0050] After the terephthalic acid supply unit 730 (described later) starts supplying terephthalic acid (TPA), in addition to EG formed by the bond between BHETs, water is also generated as a by-product of the polymerization reaction by the bond between BHET and TPA. Therefore, if the polymerization reaction progress rate detection unit 720 is configured to measure only EG, it will be impossible to accurately grasp the progress rate of the polymerization reaction after the start of TPA supply. However, since the main purpose of the polymerization reaction progress rate detection unit 720 in this embodiment is to determine the timing for starting the supply of TPA by the terephthalic acid supply unit 730, there is no practical problem even if it becomes impossible to track the progress rate of the polymerization reaction after the start of TPA supply. Thus, the polymerization reaction progress rate detection unit 720 according to this embodiment may detect the progress rate of the polymerization reaction by measuring at least the by-products (e.g., EG) generated by the polymerization reaction before the terephthalic acid supply unit 730 supplies terephthalic acid.

[0051] Alternatively, the polymerization reaction progress rate detection unit 720 may detect the progress rate of the polymerization reaction through direct measurement of unreacted or unbonded depolymerization products and reacted or bonded polymers or oligomers in the polymerization reaction unit 710 (e.g., polymerization reaction tank 400). For example, the polymerization reaction progress rate detection unit 720 may detect the progress rate of the polymerization reaction through measurement of the average molecular weight of a monomer such as PET (i.e., BHET or the like as a depolymerization product), oligomer, and polymer present in the polymerization reaction unit 710 (e.g., polymerization reaction tank 400).

[0052] Alternatively, the polymerization reaction progress rate detection unit 720 may detect the progress rate of the polymerization reaction through various changes that occur as the polymerization reaction progresses. For example, as the polymerization reaction progresses in the polymerization reaction tank 400, the amount of polymers and oligomers with high molecular weights increases, causing the viscosity of the fluid in the polymerization reaction tank 400 to increase. This increases the torque required to stir the fluid at a desired rotation speed. Therefore, the progress rate of the polymerization reaction can be indirectly detected by monitoring the torque of a motor or the like that rotates the stirring blades 420 that stir the fluid in the polymerization reaction tank 400. Alternatively, the polymerization reaction progress rate detection unit 720 may indirectly detect the progress rate of the polymerization reaction through, for example, measuring the viscosity or IV value of the fluid in the polymerization reaction tank 400.

[0053] The terephthalic acid supply unit 730 supplies terephthalic acid to the polymerization reaction unit 710 (at least one of the polymerization reaction tank 400, by-product removal device 500, polymer supply unit 600, and the path connecting them). The main purpose of the terephthalic acid here is to bond (adhere) oligomers such as PET produced during the polymerization reaction in the polymerization reaction unit 710 through an esterification reaction. The terephthalic acid is preferably introduced in the form of a powder with a large surface area to promote the polymerization reaction. Furthermore, the terephthalic acid is preferably introduced uniformly into the polymerization reaction tank 400, etc. For example, if non-uniform terephthalic acid, in which the powder particles have bonded together to form large clumps, is introduced, the degree of adhesion between the oligomers may vary from place to place, which may impair the properties of the resulting resin, which is undesirable.

[0054] Figure 5(B) schematically illustrates the adhesive function of terephthalic acid (TPA). Figure 5(A) schematically illustrates a comparative example in which PET oligomers bond directly to each other in the absence of TPA (a reaction occurring before the addition of TPA). The reaction shown in Figure 5(A) is essentially the same as the "(re)polymerization" shown in Figure 2. Specifically, Figure 5(A) illustrates two PET oligomers formed by the bonding of n units of BHET (n is a natural number significantly greater than 1), and the ends of these two PET oligomers bond to produce a PET polymer derived from 2n units of BHET. Although omitted in Figure 5(A), this reaction (transesterification) also produces EG as a by-product (see Figure 2). The PET oligomers, which are the reactants of this reaction, have a larger molecular weight than the monomer BHET, resulting in slower molecular motion and less chance of their ends coming into contact with each other. Furthermore, the large molecular weight of the PET oligomer makes it more likely that EG produced as a by-product will remain in the polymer / oligomer matrix or bulk of the polymer / oligomer, leading to elimination inhibition. As described above, the slowing of molecular motion due to the increase in molecular weight and the increased likelihood of EG elimination inhibition combine to significantly decrease the reaction rate in Figure 5(A) as the PET oligomer becomes larger (n becomes larger).

[0055] In contrast, in Figure 5(B), TPA, which has a significantly smaller molecular weight than the PET oligomer, moves (moves around) quickly within the PET oligomer group, increasing the frequency of contact with the terminals of each PET oligomer, allowing for efficient bonding. As a result, the PET oligomers, which are difficult to bond directly as in Figure 5(A), are efficiently bonded or adhered by TPA, which functions as an adhesive. This can solve the problem of reduced reaction rate as in Figure 5(A). Note that, although not shown in Figure 5(B), water is produced as a by-product by this reaction (esterification reaction).

[0056] Unlike in FIG. 5(A), the "PET polymer" as the product of the reaction in FIG. 5(B) contains a structure derived from TPA. However, as long as the proportion of the TPA-derived structure in the final product (PET polymer) is not excessively large, the impact of the TPA-derived structure on the quality of the final product can be ignored. Therefore, the product in FIG. 5(B) can be considered the same as the general PET polymer in FIG. 5(A). As described below, this embodiment has the advantage that TPA is supplied "during" the polymerization reaction, thereby naturally suppressing the proportion of TPA-derived structures in the final product. For example, by supplying TPA after 60% of BHET has bonded in the transesterification reaction in FIG. 5(A), the proportion of TPA-derived structures introduced by the esterification reaction in FIG. 5(B) can be limited to a maximum of 40% in terms of BHET.

[0057] As described above, the TPA supplied by the terephthalic acid supply unit 730 can increase the reaction rate of the polymerization reaction in the polymerization reaction unit 710. However, as shown in the experimental example in FIG. 6, it has been found that supplying TPA at a stage when the polymerization reaction has not progressed sufficiently inhibits the progress of the polymerization reaction.

[0058] 6 shows the time course of the BHET conversion rate (i.e., the rate of progress of the polymerization reaction) depending on whether or not TPA was added and the timing of its addition. "No TPA added" represents the conversion rate when no TPA was added (the reaction shown in FIG. 5A mainly proceeded over the entire period). "Initial TPA addition" represents the conversion rate when TPA is supplied simultaneously with the start of the polymerization reaction. (At the beginning of the reaction, because n of BHET or the oligomer is small, the reactions of Figure 5(A) and Figure 5(B) mainly proceed simultaneously as competitive reactions, and a BHET-TPA-like product is also produced. With the passage of reaction time, the molecular weight of the product increases, and the reaction in which TPA is inserted between oligomers as shown in Figure 5(B) becomes dominant. However, because TPA is consumed in the competitive reactions at the beginning of the reaction, the reaction of Figure 5(B) becomes less likely to occur from the middle of the reaction onwards. "Mid-stage TPA addition" represents the conversion rate when TPA is supplied a predetermined time T after the start of the polymerization reaction (or after the conversion rate or progress rate reaches a predetermined progress rate C). (Before the predetermined time T, the reaction of Figure 5(A) mainly proceeds, and after the predetermined time T, the reaction of Figure 5(B) mainly proceeds.)

[0059] As shown in the graph for "Initial TPA Addition," when TPA was added simultaneously with the start of the polymerization reaction, the reaction rate (rate of increase in conversion rate) of the polymerization reaction was observed to be inferior even to the "No TPA Added" case, in which no TPA was added at all. On the other hand, as shown in the graph for "Mid-Term TPA Addition," when TPA was added after the polymerization reaction had progressed to a certain extent (after reaching a predetermined time T or a predetermined progress rate C), the effect of boosting or accelerating the reaction rate compared to the "No TPA Added" case was observed. Thus, in order to efficiently advance the polymerization reaction, it is preferable to add TPA at a stage midway through the polymerization reaction, once the polymerization reaction has progressed to a certain extent. Note that the addition of TPA accelerates the polymerization reaction and increases the viscosity of the fluid in the polymerization reaction vessel 400, so the rotation speed and torque of the agitator blade 420 may be increased in conjunction with the timing of the TPA addition.

[0060] Therefore, the terephthalic acid supply unit 730 according to the present embodiment supplies terephthalic acid to the polymerization reaction unit 710 after the polymerization reaction in the polymerization reaction unit 710 has progressed to a predetermined extent or more but before the polymerization reaction is completed. As in the example of FIG. 4 , when the polymerization reaction progress rate detection unit 720 is provided, the terephthalic acid supply unit 730 may supply terephthalic acid to the polymerization reaction unit 710 after the progress rate of the polymerization reaction detected by the polymerization reaction progress rate detection unit 720 has reached a predetermined progress rate C or more that is significantly greater than 0% (e.g., 30% or more) but before it reaches 100%. Alternatively, when the polymerization reaction progress rate detection unit 720 is not provided, the terephthalic acid supply unit 730 may supply terephthalic acid to the polymerization reaction unit 710, for example, after a predetermined time T has elapsed since the polymerization reaction started in the polymerization reaction tank 400. In this case, the predetermined time T may be, for example, a time that is reasonably expected to allow the polymerization reaction to proceed to a predetermined extent (e.g., a predetermined progress rate C) or more under the reaction conditions in the polymerization reaction tank 400.

[0061] Also important is the amount of terephthalic acid to be supplied through the terephthalic acid supply unit 730. Specifically, the terephthalic acid supply unit 730 preferably supplies to the polymerization reaction unit 710 an amount of terephthalic acid that is equal to or less than a reference amount-of-substance rate M, which is obtained by subtracting the aforementioned predetermined progress rate C from 100%, relative to the amount of depolymerized polymer (BHET, etc.) supplied from the depolymerization reaction tank 300, etc. to the polymerization reaction unit 710 (strictly speaking, the polymerization reaction tank 400 constituting the front or input stage thereof).

[0062] The predetermined progress rate C for determining the timing of TPA addition can be set arbitrarily as long as it significantly accelerates the polymerization reaction as shown in FIG. 6 . For example, it is between 30% and 95%, preferably between 40% and 85%, and more preferably between 60% and 80%. At the aforementioned preferred predetermined progress rate C, the molecular weight of the product is sufficiently large, and the reaction in which TPA is inserted between oligomers, as shown in FIG. 5(B), prevails. Furthermore, the increase in progress rate with reaction time slows. Therefore, adding TPA at the predetermined progress rate C can further enhance the effect of boosting or accelerating the reaction rate. In this case, the reference substance amount ratio M, which is the ratio obtained by subtracting the predetermined progress rate C from 100%, is between 5% and 70%, preferably between 15% and 60%, and more preferably between 20% and 40%. In the following, the predetermined progress rate C is assumed to be 60% as an example. In this case, the reference substance amount ratio M is 40%.

[0063] FIG. 7 shows data on the time course of the BHET conversion (i.e., the progress rate of the polymerization reaction) depending on whether or not TPA was added and the amount of TPA added. "BHET" represents the conversion rate when no TPA was added. "BHET + TPA 20 mol%" represents the conversion rate when an appropriate amount (20%) of TPA not greater than the reference substance amount M (about 40%) was added a predetermined time T after the start of the polymerization reaction (or after the conversion rate or progress rate reached a predetermined progress rate C (about 60%)). "BHET + TPA over amount" represents the conversion rate when an excess amount (55%) of TPA exceeding the reference substance amount M (about 40%) was added a predetermined time T after the start of the polymerization reaction (or after the conversion rate or progress rate reached a predetermined progress rate C (about 60%)).

[0064] As shown in the graph for "BHET + TPA over amount," the polymerization reaction rapidly accelerates when an excess amount of TPA is supplied, and the conversion rate quickly reaches its maximum of 100%. Thus, from the perspectives of conversion rate and reaction rate, adding an excess amount of TPA appears to be ok. However, as shown in Figure 8, in reality, significant deterioration in the chemical properties related to the quality of the final product (PET) was observed. Specifically, as shown in Figure 8, when an excess amount of TPA was supplied, the IV value, number average molecular weight, and average degree of polymerization of "TPA over amount" were all inferior to those of "TPA 20 mol%," when an appropriate amount of TPA was supplied. Thus, from the perspectives of both the reaction rate shown in Figure 7 and the chemical properties of the final product shown in Figure 8, it is desirable to supply an appropriate amount of TPA at or below the reference substance ratio M (approximately 40%).

[0065] Here, the reference substance amount ratio M, which serves as the basis for "appropriate amount" and "excessive amount," is 100% minus the predetermined progress ratio C, as described above. For example, if the predetermined progress ratio C is 60%, when the polymerization reaction progresses to that ratio, 40% (reference substance amount ratio M) of the depolymerized BHET or other polymers remains unreacted. Even if TPA exceeding 40% is supplied under this condition, at least a portion of the unreacted TPA will not react with BHET or other polymers. Furthermore, such excess TPA significantly increases the number of undesirable carboxylic acid terminals in the final product, such as PET. Thus, the excess TPA remaining unreacted in the final product and the resulting excess carboxylic acid terminals are thought to deteriorate the chemical properties of the final product. On the other hand, if the amount of TPA is less than the reference substance amount M (equivalent to 40%), theoretically all of it can react with BHET or other polymers. Therefore, no significant amount of TPA remains in the final product, and the desired chemical properties are likely to be achieved.

[0066] The pressure reduction section 740 reduces the pressure inside the polymerization reaction section 710 (particularly, the polymerization reaction tank 400) while terephthalic acid is being supplied from the terephthalic acid supply section 730. The pressure reduction section 740 may be configured as a vacuum pump or the like attached to the polymerization reaction tank 400. In the reduced pressure or vacuum environment created by the pressure reduction section 740, a reaction involving terephthalic acid, such as that shown in FIG. 5(B), proceeds efficiently. Reactions not involving terephthalic acid, such as those shown in FIG. 5(A), can also be accelerated in a reduced pressure environment. However, as mentioned above, at the initial stage of the reaction, for example, when the conversion rate is less than 60%, large amounts of volatile EG and the like are generated, making it difficult to achieve sufficient pressure reduction with a vacuum pump of a practical size. On the other hand, in the reaction shown in FIG. 5(B), if TPA is added during the polymerization reaction, as shown in FIG. 6, oligomers with a certain n are produced. When oligomer adhesion (FIG. 5(B)) is performed by adding TPA under this condition, the amount of water generated as a by-product is limited, thereby preventing excessive load on the vacuum pump. Before terephthalic acid is supplied by the terephthalic acid supply unit 730, an inert gas such as a rare gas such as nitrogen or argon may be supplied into the polymerization reaction unit 710 (particularly, the polymerization reaction tank 400) instead of using a pressure reduction unit 740 such as a vacuum pump.

[0067] 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.

[0068] The configuration, operation, and function of each device and method described in the embodiments can be realized by hardware resources, software resources, or a combination of hardware and software resources. Examples of hardware resources include processors, ROM, RAM, and various integrated circuits. Examples of software resources include operating systems, applications, and other programs.

[0069] The present disclosure relates to polymerization systems and the like.

[0070] 1 injection molding machine, 100 chemical recycling device, 300 depolymerization reaction tank, 400 polymerization reaction tank, 500 by-product removal device, 600 polymer supply unit, 700 polymerization system, 710 polymerization reaction unit, 720 polymerization reaction progress rate detection unit, 730 terephthalic acid supply unit, 740 pressure reduction unit.

Claims

1. A polymerization system comprising: a polymerization reaction section that synthesizes a polyester depolymer into a polymer through a polymerization reaction; and a terephthalic acid supply section that supplies terephthalic acid to the polymerization reaction section after the polymerization reaction has progressed to a predetermined extent or more but before the polymerization reaction is completed.

2. The polymerization system according to claim 1, further comprising a polymerization reaction progress rate detection unit that detects the progress rate of the polymerization reaction, and wherein the terephthalic acid supply unit supplies terephthalic acid to the polymerization reaction unit after the progress rate reaches or exceeds a predetermined progress rate greater than 0% but before it reaches 100%.

3. The polymerization system according to claim 2, wherein the terephthalic acid supply unit supplies to the polymerization reaction unit an amount of terephthalic acid equal to or less than a reference amount of substance rate, which is 100% minus the predetermined progress rate, relative to the amount of substance of the depolymerization supplied to the polymerization reaction unit.

4. The polymerization system of claim 3, wherein the predetermined progress rate is 60% and the reference substance amount rate is 40%.

5. The polymerization system according to claim 2, wherein the polymerization reaction progress rate detection unit detects the progress rate of the polymerization reaction through measurement of by-products produced by the polymerization reaction at least before terephthalic acid is supplied by the terephthalic acid supply unit.

6. The polymerization system according to any one of claims 1 to 5, further comprising a pressure reducing section that reduces the pressure inside the polymerization reaction section when terephthalic acid is being supplied by the terephthalic acid supply section.

7. The polymerization system according to any one of claims 1 to 5, wherein the polymerization reaction section comprises a polymerization reaction tank into which the depolymerization is supplied and the polymerization reaction is initiated, and a by-product removal device that is provided downstream of the polymerization reaction tank and removes by-products generated by the polymerization reaction, the by-product removal device allowing the polymerization reaction to continue, and the terephthalic acid supply section supplies terephthalic acid to at least one of the polymerization reaction tank and the by-product removal device.

8. The polymerization system of any one of claims 1 to 5, wherein the polyester is polyethylene terephthalate and the depolymerized polymer is bis(2-hydroxyethyl) terephthalate.

9. A method for producing a polymer, comprising: synthesizing a depolymerized polyester into a polymer by a polymerization reaction in a polymerization reaction section; and supplying terephthalic acid to the polymerization reaction section after the polymerization reaction has progressed to a predetermined extent or more but before the polymerization reaction is completed.

10. A chemical recycling system comprising: a depolymerization reaction tank that decomposes polyester polymers into depolymers by a depolymerization reaction; a polymerization reaction section that synthesizes the depolymers into polymers by a polymerization reaction; and a terephthalic acid supply section that supplies terephthalic acid to the polymerization reaction section after the polymerization reaction has progressed to a predetermined extent or more but before the polymerization reaction is completed.

11. The chemical recycling system according to claim 10, further comprising a molding machine connected to the polymerization reaction section for molding the polymer after the polymerization reaction is completed.

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