Polyester recycling system and polyester recycling method

Abstract

To provide a polyester recycling system and a polyester recycling method capable of effectively utilizing a polyester solution after removing impurities.SOLUTION: A polyester recycling system according to the present disclosure comprises: a dissolution unit that supplies a monomer solution generated by decomposing polyester to a polyester raw material, which is a substance containing a polyester, to generate a polyester solution in which the polyester of the polyester raw material is dissolved; a separation unit that removes impurities, which are components other than the polyester contained in the polyester raw material, from the polyester solution; a processing unit that executes a prescribed process on the polyester solution that has passed through the separation unit; and a pellet production unit that produces recycled polyester pellets using the polyester solution on which the prescribed treatment has been executed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] There are known techniques for separating impurities from polyesters (PEs) in order to recycle polyesters. For example, Patent Document 1 below describes that polyethylene terephthalate (PET) waste is introduced into ethylene glycol (EG) and depolymerized to obtain bis(2-hydroxyethyl) terephthalate (BHET), and that foreign matter other than PET is removed using a filter during or after the depolymerization reaction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4065659 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technology described in Patent Document 1 requires complex depolymerization and purification steps, which is expected to require huge capital investment costs, and the utility costs for operating the plant are also high, which is a problem.

[0005] In view of the above problems, the present disclosure aims to provide a polyester recycling system and a polyester recycling method that can effectively utilize a polyester solution after impurities have been removed. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the objectives, the polyester recycling system of the present disclosure comprises a dissolution section that supplies a solution of monomers produced by decomposing polyester to a polyester raw material, which is a substance containing polyester, to produce a polyester solution in which the polyester from the polyester raw material is dissolved; a separation section that removes impurities, which are components other than polyester contained in the polyester raw material, from the polyester solution; a processing section that performs a predetermined process on the polyester solution that has passed through the separation section; and a pellet production section that produces recycled polyester pellets using the polyester solution that has been subjected to the predetermined process.

[0007] In order to solve the above-mentioned problems and achieve the objectives, the polyester recycling method of the present disclosure includes the steps of supplying a solution of monomers produced by decomposing polyester to a polyester raw material, which is a substance containing polyester, to produce a polyester solution in which the polyester from the polyester raw material is dissolved; removing impurities, which are components other than polyester contained in the polyester raw material, from the polyester solution; and performing a predetermined process on the polyester solution from which the impurities have been removed. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a polyester recycling system and a polyester recycling method that can effectively utilize a polyester solution after impurities have been removed. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a flowchart showing an overview of a polyester recycling system according to the present disclosure. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a separation system according to the present disclosure. [Figure 3] FIG. 3 is a diagram illustrating an example of the configuration of a control device according to the present disclosure. [Figure 4]FIG. 4 is a flowchart showing the flow of the separation method according to the present disclosure. [Figure 5] FIG. 5 is a diagram showing an example of the configuration of a polyester recycling system according to the present disclosure. [Figure 6] FIG. 6 is a flowchart showing the process flow of the first embodiment of the polyester recycling system according to the present disclosure. [Figure 7] FIG. 7 is a flowchart showing a process flow of the second embodiment of the polyester recycling system according to the present disclosure. [Figure 8] FIG. 8 is a flowchart showing a process flow of a third embodiment of a polyester recycling system according to the present disclosure. [Figure 9] FIG. 9 is a flowchart showing a process flow of a fourth embodiment of the polyester recycling system according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present disclosure is not limited to the embodiments described below.

[0011] (Outline of polyester recycling system processing) First, an overview of the processing by the polyester recycling system 100 according to the present disclosure will be described using Fig. 1. Fig. 1 is a flowchart showing an overview of the polyester recycling system according to the present disclosure. The overview of the processing by the polyester recycling system 100 according to the present disclosure will be described along the flow shown in Fig. 1.

[0012] First, the polyester recycling system 100 flaks the PET raw material Pm (Step S1). Flaking is a process in which the PET raw material is fed into a cleaning and crushing device and mechanically crushed into small pieces. Next, the polyester recycling system 100 dissolves the flaked PET raw material Pm in a carboxylic acid-derived monomer D to produce a PET solution (Step S2). Next, the polyester recycling system 100 removes foreign matter from the produced PET solution and separates it into a PET solution and impurities (Step S3). Next, the polyester recycling system 100 performs a predetermined process on the PET solution (Step S4). Next, the polyester recycling system 100 uses the PET solution after the predetermined process to produce recycled PET pellets (Step S5). Next, the polyester recycling system 100 uses the recycled PET pellets to mold recycled PET products (Step S6).

[0013] Among the processes of the polyester recycling system 100, steps S1 to S3 are performed by a separation system 1 of the polyester recycling system 100. A detailed description of the separation system 1 will be given later prior to a detailed description of other components of the polyester recycling system 100.

[0014] In this way, the polyester recycling system 100 according to the present disclosure separates the PET raw material into a PET solution and impurities, then performs a predetermined process on the PET solution, produces recycled PET pellets, and molds the recycled PET pellets into recycled PET products. This allows for effective use of the PET solution from which impurities have been removed.

[0015] Next, the meanings of terms used in this specification will be explained below.

[0016] (PET raw material) PET raw material Pm is a substance containing PET. PET raw material Pm can also be considered mixed plastic waste, and may be material collected at a municipal recycling facility or the like. In other words, PET raw material Pm does not contain only PET components, but also many other components. Examples of components other than PET contained in PET raw material Pm include plastics other than PET, such as polyethylene (PE), polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC), as well as metals, pigments, and polymerization catalysts. Hereinafter, components other than PET contained in PET raw material Pm will be referred to as impurities R.

[0017] In this embodiment, the raw material to be depolymerized is a PET-containing material. However, other polyester-containing materials can also be used. Examples of polyester raw materials include, but are not limited to, polyethylene terephthalate (PET), polyethylene butylene terephthalate (PEBT), polybutylene terephthalate (PBT), polycyclohexane dimethyl terephthalate (PCT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), and polycarbonate (PC). The most typical application is the recycling of PET bottles. Other examples include PET film, such as photographic film; PET tape, such as magnetic tape; PET fiber, which is used as polyester fiber; and PET sheet, which is used for cups, trays, and transparent packaging.

[0018] (Reaction solvent) The reaction solvent M is a solvent that reacts with PET to depolymerize the PET. The reaction solvent M may be, for example, at least one of methanol, ethanol, water, and ethylene glycol (EG).

[0019] (carboxylic acid monomer) The carboxylic acid-derived monomer D is a monomer having a carboxyl group produced by the depolymerization reaction of PET. Monomer D is preferably, for example, a terephthalic acid monomer, and specifically may be dimethyl terephthalate (DMT).

[0020] (Alcohol monomer) The alcohol monomer E is an alcohol monomer produced by the depolymerization reaction of PET. The alcohol monomer E may be, for example, a dihydroxy compound (dihydric alcohol), or more specifically, ethylene glycol (EG).

[0021] (About the separation system) Next, a separation system 1 according to the present disclosure will be described with reference to FIG. 2. FIG. 2 is a diagram showing an example of the configuration of the separation system according to the present disclosure. The separation system 1 according to the present disclosure is a system that separates a PET raw material Pm into a PET solution and impurities. As shown in FIG. 2, the separation system 1 has a raw material storage section 10, a dissolving section 12, a solid-liquid separation section 13, a foreign matter recovery section 16, a storage section 20, a removal section 26, and a control device 30. The solid-liquid separation section 13, the foreign matter recovery section 16, the storage section 20, and the removal section 26 are collectively referred to as the separation section. The configuration of these sections will be described in order below.

[0022] (Regarding the raw material storage section) The raw material storage section 10 receives the PET raw material Pm, stores the PET raw material Pm, and distributes the PET raw material Pm. Specifically, the raw material storage section 10 may be, for example, a hopper. The hopper holds any type of particulate or flowable material and distributes it from the bottom as needed. The raw material storage section 10 stores flaked PET raw material Pm, and the PET raw material Pm may be of any shape or size. The raw material storage section 10 is connected to the melting section 12, which will be described later, via an inlet pipe 10a. That is, the PET raw material Pm introduced into the raw material storage section 10 is supplied to the melting section 12 through the inlet pipe 10a.

[0023] The inlet pipe 10a is provided with an adjusting unit 10b that adjusts the amount of PET raw material Pm supplied from the raw material storage unit 10 to the melting unit 12. The adjusting unit 10b is, for example, an on-off valve, and specifically may be realized by a ball valve, a diaphragm valve, a butterfly valve, or the like. When the valve is open, the adjusting unit 10b supplies the PET raw material Pm in the raw material storage unit 10 to the melting unit 12, and when the valve is closed, the adjusting unit 10b stops the supply of the PET raw material Pm in the raw material storage unit 10 to the melting unit 12. However, the adjusting unit 10b is not limited to an on-off valve and may be any mechanism that can adjust the supply of the PET raw material Pm to the melting unit 12.

[0024] (About the melting part) The dissolving unit 12 is a tank that stores the dissolving solution Pd. The dissolving solution Pd is a solution generated by mixing the PET raw material Pm with a monomer D. Here, the PET components contained in the PET raw material Pm dissolve in the monomer D, but impurities R, which are components other than PET contained in the PET raw material Pm, remain without dissolving in the monomer D. Therefore, the dissolving solution Pd contains a PET solution P in which the PET contained in the PET raw material Pm is dissolved in the monomer D, and the impurities R contained in the PET raw material Pm. In this embodiment, the PET raw material Pm is mixed with the monomer D, but instead of the monomer D, a monomer E, which is an alcohol component generated by depolymerizing the PET raw material Pm, may be used.

[0025] Monomer D and PET raw material Pm are supplied to dissolving section 12. Inside dissolving section 12, PET contained in PET raw material Pm dissolves in monomer D, while impurities R remain undissolved in monomer D, producing PET solution P and solution Pd containing impurities R. By dissolving PET contained in PET raw material Pm in monomer D in this way, the viscosity of PET can be reduced and fluidity can be improved. Note that the PET solution P does not necessarily have to be entirely dissolved in monomer D; at least a portion of PET may be insoluble in monomer D. Furthermore, if there is a component soluble in monomer D among the components other than PET contained in PET raw material Pm, the PET solution P may also contain that component dissolved in monomer D.

[0026] The melting section 12 is provided with a heating section 12A. The heating section 12A heats the interior of the melting section 12, thereby heating the monomer D and the PET raw material Pm supplied to the melting section 12 to a predetermined temperature. The heating section 12A may be realized, for example, by a method in which a heat medium (steam or hot oil) is passed through the inside of a jacket, an electric heater, a microwave heater, or the like. The predetermined temperature is a temperature at which the PET can be dissolved in the monomer D. By heating at this predetermined temperature, the PET contained in the PET raw material Pm can be properly dissolved in the monomer D.

[0027] The predetermined temperature is preferably 140°C or higher and 300°C or lower, more preferably 160°C or higher and 280°C or lower, and even more preferably 190°C or higher and 250°C or lower. The impurities R contain components that melt when heated to the predetermined temperature (the temperature at which PET can be dissolved in the monomer D). Therefore, the impurities R are contained in the solution Pd in ​​an at least partially melted state.

[0028] (About the solid-liquid separation section) The solid-liquid separation section 13 is disposed inside the dissolving section 12. The solid-liquid separation section 13 collects solid impurities R contained in the solution Pd stored in the dissolving section 12 and separates the solid impurities R from the solution Pd. The solid-liquid separation section 13 may be, for example, a mesh filter that collects solids larger than the size of the pores by allowing the liquid to pass through a large number of pores. The solid-liquid separation section 13 may be, for example, a container-shaped structure with an open top and may be disposed at a predetermined distance from the side and bottom of the dissolving section 12. The solid-liquid separation section 13 is disposed downstream of the inlet pipe 10a and the supply pipe through which the monomer D is supplied, and upstream of the inlet pipe 12a that supplies the solution Pd from the dissolving section 12 to the downstream storage section 20. That is, the solution Pd flowing into the inlet pipe 12a from the dissolving section 12 passes through the solid-liquid separation section 13 before flowing into the inlet pipe 12a. This allows the solids larger than the opening diameter of the mesh to be collected in the solid-liquid separation section 13. The opening diameter of the mesh in the solid-liquid separation section 13 is preferably set to 1 mm or more and 50 mm or less.

[0029] The solid-liquid separation unit 13 employs a filtering method using a mesh filter, but is not limited to this. The solid-liquid separation unit 13 may separate the impurities R from the solution Pd by centrifugal separation, which stirs the interior of the dissolving unit 12 around a predetermined axis and moves the impurities radially outward from the rotating shaft. The solid-liquid separation unit 13 is not limited to filtration or centrifugal separation as long as it can separate solid impurities of a predetermined size or larger from the solution Pd.

[0030] (Foreign object collection section) The foreign matter recovery unit 16 recovers solid impurities collected by the solid-liquid separation unit 13. The foreign matter recovery unit 16, for example, moves the filter of the solid-liquid separation unit 13 to recover the adhering impurities. The solid-liquid separation unit 13 may also include a press device that presses impurities adhering to a mesh filter against the filter and squeezes out the solution Pd contained in the impurities. By squeezing the solution with the press device before the foreign matter recovery unit 16 recovers the impurities, it is possible to leave more solution Pd inside the separation system 1. When the solid-liquid separation unit 13 separates impurities by centrifugation, the foreign matter recovery unit 16 recovers the impurities from a region where the impurities accumulate by centrifugation.

[0031] After discharging the dissolving solution Pd from the dissolving unit 12, methanol can be supplied to the dissolving unit 12 to wash the remaining waste clothing, etc., and the DMT adhering to the waste clothing, etc. can be dissolved and recovered in the methanol. The DMT recovery solution can be separated into methanol and DMT by distillation in a methanol purification system, and the DMT can be recovered.

[0032] (Regarding the storage section) The reservoir 20 is a tank in which the dissolving liquid Pd is stored. The reservoir 20 is connected to the dissolving unit 12 via an inlet pipe 12a. That is, the dissolving liquid Pd inside the dissolving unit 12 is supplied to the reservoir 20 from the dissolving unit 12 through the inlet pipe 12a. The inlet pipe 12a is provided with an adjustment unit 12a1 that adjusts the amount of the dissolving liquid Pd supplied from the dissolving unit 12 to the reservoir 20. The adjustment unit 12a1 is, for example, an on-off valve (which may be realized by the above-mentioned valve). When the valve is open, the adjustment unit 12a1 supplies the dissolving liquid Pd inside the dissolving unit 12 to the reservoir 20, and when the valve is closed, the adjustment unit 12a1 stops supplying the dissolving liquid Pd inside the dissolving unit 12 to the reservoir 20. However, the adjustment unit 12a1 is not limited to an on-off valve and may be any mechanism that can adjust the supply of the dissolving liquid Pd to the reservoir 20. The reservoir 20 may be connected to the dissolving section 12 via an introduction pipe 12a, but a temporary reservoir for temporarily storing the dissolving liquid Pd may also be provided between the dissolving section 12 and the reservoir 20.

[0033] In the storage unit 20, the stored solution Pd is separated by gravity into the PET solution P and impurities R according to the difference in density of the components contained in the solution Pd. Here, the impurities R separated in the storage unit 20 are impurities that were not recovered by the solid-liquid separation unit 13 described above and moved to the storage unit 20 together with the solution Pd. By leaving the solution Pd stored inside the storage unit 20 to stand, the solution Pd is separated into the PET solution P and the impurities R according to their respective densities.

[0034] Specifically, the solution Pd stored in the storage unit 20 is separated by gravity into a layer of first impurities R1, a layer of PET solution P, and a layer of second impurities R2 according to the density differences of the individual components. The layer of first impurities R1 is formed vertically below the layer of PET solution P. That is, the first impurities R1 are impurities R that do not dissolve in monomer D and have a higher density than the PET solution P. The first impurities R1 settle within the PET solution P inside the storage unit 20 to form the layer of first impurities R1. Meanwhile, the layer of second impurities R2 is formed vertically above the layer of PET solution P. That is, the second impurities R2 are impurities R that do not dissolve in monomer D and have a lower density than the PET solution P. The second impurities R2 rise within the PET solution P inside the storage unit 20 to form the layer of second impurities R2.

[0035] The dissolving liquid Pd inside the reservoir 20 is maintained at a predetermined temperature or higher (a temperature at which PET can be dissolved in the monomer D). The first impurity R1 and the second impurity R2 are components of the impurities R that melt when heated to a predetermined temperature, and therefore exist in a molten state inside the reservoir 20. The first impurities R1 and the second impurities R2 are, for example, plastics other than PET (polyethylene other than PET, polystyrene, polypropylene, polyvinyl chloride, etc.).

[0036] The layer of PET solution P contains a third impurity R3. The third impurity R3 is a component of impurities R that is insoluble in monomer D and does not melt even at a predetermined temperature (the temperature at which PET can be dissolved in monomer D). In other words, the third impurity R3 is not separated from the PET solution P even by gravity separation, and exists in the PET solution P in an unmelted solid state. The third impurity R3 is dispersed in the PET solution P. The third impurity R3 is, for example, a dye, a pigment, or a polymerization catalyst.

[0037] A discharge pipe 20a is connected to the storage section 20. The discharge pipe 20a is a pipe for discharging the first impurities R1 separated into a layer below the PET solution P from the storage section 20. The discharge pipe 20a is connected to a position in the storage section 20 where a layer of the first impurities R1 is formed, for example, connected to the bottom of the storage section 20. A first discharge section 22a is provided in the discharge pipe 20a. The first discharge section 22a discharges the first impurities R1 inside the storage section 20 from the storage section 20. The first discharge section 22a is, for example, a pump.

[0038] A discharge pipe 20b is connected to the storage part 20. The discharge pipe 20b is a pipe for discharging the second impurity R2, which has separated into an upper layer above the PET solution P, from the storage part 20. The discharge pipe 20b is connected to a position in the storage part 20 where a layer of the second impurity R2 is formed, and is connected vertically above the discharge pipe 20a. The storage part 20 is fitted with second discharge parts 22b1, 22b2 that discharge the second impurity R2 in the storage part 20 from the storage part 20.

[0039] The second discharge unit 22b1 is a skimmer provided at the liquid surface of the PET solution P, and collects (scrapes off) the second impurities R2 floating on the liquid surface of the PET solution P. The second discharge unit 22b2 is provided in the discharge pipe 20b and is a mechanism, such as a pump, that discharges the second impurities R2 collected in the second discharge unit 22b1 via the discharge pipe 20b. In this way, the second discharge units 22b1 and 22b2 are provided as mechanisms for discharging the second impurities R2, but the configuration of the second discharge unit that discharges the second impurities R2 is not limited to this and may be any configuration.

[0040] The first impurity R1 and the second impurity R2 separated from the PET solution P in the storage unit 20 are discharged to the outside of the storage unit 20 by the first discharge unit 22a and the second discharge units 22b1 and 22b2. This removes the first impurity R1 and the second impurity R2 from the PET solution P. Hereinafter, when there is no need to distinguish between the first discharge unit 22a and the second discharge units 22b1 and 22b2, they will be referred to as discharge units 22. Note that in the above description, an example has been described in which the impurities R include the first impurity R1, which has a density greater than that of the PET solution P, and the second impurity R2, which has a density less than that of the PET solution P. However, this is not limiting, and the impurities R may include only one of the first impurity R1 and the second impurity R2.

[0041] An inlet pipe 20c is connected to the storage section 20. The inlet pipe 20c is a pipe for introducing the PET solution P, from which the impurities R have been separated, that is discharged from the storage section 20 into the removal section 26, which will be described later. The inlet pipe 20c is connected to a position in the storage section 20 where a layer of the PET solution P is formed, and may be connected, for example, to a position between the discharge pipes 20a and 20b in the vertical direction. The inlet pipe 20c is provided with an outlet section 24. The outlet section 24 discharges the PET solution P from inside the storage section 20 and leads it to the inlet pipe 20c. The outlet section 24 may be realized, for example, by a pump.

[0042] (Regarding the removal part) The removal unit 26 removes the third impurity R3 contained in the PET solution P from the PET solution P. The removal unit 26 is connected to the introduction pipe 20c through which the PET solution P is drawn out from the storage unit 20 described above. The removal unit 26 includes a first removal unit 26a and a second removal unit 26b.

[0043] The first removal unit 26a collects solid components contained in the PET solution P. The first removal unit 26a may be realized by, for example, a filter.

[0044] The second removal unit 26b adsorbs solid components contained in the PET solution P that were not repaired by the first removal unit 26a. The second removal unit 26b may be realized by an adsorption tower. The second removal unit 26b also filters the solid components contained in the PET solution P that were not repaired by the first removal unit 26a through a packed bed in the packed tower. The second removal unit 26b may perform at least one of adsorption and filtration of the solid components.

[0045] The PET solution P introduced from the reservoir 20 to the inlet pipe 20c is introduced into the first removal unit 26a, where at least a portion of the third impurities R3 contained in the PET solution P is collected by the first removal unit 26a. The third impurities R3 collected in the first removal unit 26a are then discharged to the outside through the discharge pipe 26a1 connected to the first removal unit 26a. In the example of FIG. 2, the discharge pipe 26a1 merges with the discharge pipe 20a, but it does not have to merge with the discharge pipe 20a.

[0046] Meanwhile, the PET solution P from which at least a portion of the third impurity R3 has been removed by the first removal unit 26a is discharged from the first removal unit 26a and introduced into the second removal unit 26b. In the second removal unit 26b, the third impurity R3 remaining in the PET solution P is adsorbed by or filtered out of the second removal unit 26b and removed from the PET solution P. The third impurity R3 adsorbed by or filtered out of the second removal unit 26b is, for example, a pigment or a polymerization catalyst. The PET solution P from which the third impurity R3 has been removed by the second removal unit 26b is discharged from the second removal unit 26b and introduced into a processing unit 40, which will be described later.

[0047] In this way, the first removal unit 26a and the second removal unit 26b are provided as a mechanism for removing the third impurity R3 from the PET solution P, but the configuration of the removal unit 26 that discharges the third impurity R3 is not limited to this and may be any configuration. Also, since the impurity R may not contain the third impurity R3, the removal unit 26 is not an essential configuration.

[0048] (Regarding the control device) The control device 30 is an information processing device that manages the separation system 1 and supervises and controls the various devices and apparatuses that make up the separation system 1. The control device 30 may be realized by a computer such as a PC (Personal Computer) or a WS (Work Station). The configuration of the control device 30 will be described with reference to FIG. 3. FIG. 3 is a diagram showing an example configuration of a control device according to the present disclosure. As shown in FIG. 3, the control device 30 includes a communication unit 31, a storage unit 32, a control unit 33, an input unit 34, and a display unit 35. These components will be described in order below.

[0049] The communication unit 31 is responsible for exchanging information with the devices and apparatuses of the separation system 1. The communication unit 31 may be equipped with an antenna and exchange information wirelessly using radio waves. The communication unit 31 may also be realized by various types of electrical wiring, such as a control signal cable formed by bundling multiple electric wires, each wire having a conductor such as copper covered with an insulator, and covering the bundled wires with an electrically insulating polyvinyl chloride (PVC) sheath, and may be connected to the devices of the separation system 1 to exchange information via wired communication.

[0050] The storage unit 32 is a storage device that stores various types of information. The storage unit 32 includes a main storage device and an auxiliary storage device. The main storage device may be realized by a semiconductor memory element such as a random access memory (RAM), a read only memory (ROM), or a flash memory. The auxiliary storage device may be realized by a hard disk or a solid state drive (SSD), for example.

[0051] The control unit 33 is realized by a CPU (Central Processing Unit), an MPU (Micro Processing Unit), or the like executing various programs stored in the storage unit 32 using RAM as a work area. The control unit 33 may also be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0052] 3, the control unit 33 includes a reception unit 331, a control signal generation unit 332, and a control signal transmission unit 333. The control unit 33 realizes these functions and executes these processes by reading and executing a program (software) from the storage unit 32. Note that at least some of these functions of the control unit 33 may be realized by various electronic circuits. The control unit 33 may execute these processes using one CPU, or may be provided with multiple CPUs and execute these processes using the multiple CPUs.

[0053] The reception unit 331 receives operation information from an administrator or the like. Specifically, the reception unit 331 receives the operation information by acquiring the operation information input to the input unit 34. Upon receiving the operation information, the reception unit 331 outputs the received operation information to the control signal generation unit 332.

[0054] The control signal generating unit 332 generates a control signal to operate devices of the separation system 1. Based on the operation information received by the receiving unit 331, the control signal generating unit 332 generates a control signal to operate the adjustment unit 10b, the adjustment unit 12a1, the discharge unit 22 (the second discharge unit 22b1 and the second discharge unit 22b2), and the lead-out unit 24 of the separation system 1.

[0055] Specifically, the control signal generating unit 332 controls the adjusting unit 10b to generate a control signal for controlling the amount of polyester raw material PE supplied from the raw material storage unit 10 to the dissolving unit 12. The control signal generating unit 332 controls the adjusting unit 12a1 to generate a control signal for controlling the amount of dissolving liquid Pd supplied from the dissolving unit 12 to the storage unit 20. The control signal generating unit 332 controls the discharge unit 22 (second discharge unit 22b1 and second discharge unit 22b2) to generate a control signal for discharging, from the storage unit 20, the impurities R separated from the PET solution P in the storage unit 20. The control signal generating unit 332 controls the discharge unit 24 to generate a control signal for discharging, from the storage unit 20, the PET solution P separated from the impurities R in the storage unit 20.

[0056] The control signal transmission unit 333 transmits the control signal generated by the control signal generation unit 332 to the devices of the separation system 1. Specifically, the control signal transmission unit 333 transmits the control signal to the devices of the separation system 1 via the communication unit 31. Note that the control signal transmission unit 333 may also receive information indicating the status of the devices of the separation system 1 via the communication unit 31.

[0057] The input unit 34 receives various types of operation information from, for example, an administrator of the separation system 1. For example, the input unit 34 may receive various types of operation information using various switches, a mouse, a keyboard, a lever, a button, etc. Alternatively, the input unit 34 may receive various types of operation information from, for example, an administrator via a display surface of a touch panel.

[0058] The display unit 35 displays various types of information. For example, the display unit 35 may display a GUI (Graphical User Interface) for receiving operations related to various processes from an administrator or the like, or the status of devices in the separation system 1. The display unit 35 may be realized by a liquid crystal display, an organic EL (Electro Luminescence) display, a micro LED (Light Emitting Diode) display, or the like. The display unit 35 may also be realized by a touch panel of various types, such as a capacitive type.

[0059] (About the operation of the separation system) The operation of the separation system described above will be described with reference to FIG. 4. FIG. 4 is a flowchart illustrating the flow of the separation method according to the present disclosure. As shown in FIG. 4, the control device 30 causes the PET raw material Pm and the monomer D to be introduced into the dissolving unit 12 to generate a solution Pd (step S10). The control device 30 then supplies the solution Pd to the storage unit 20, and causes the solution Pd to be separated by gravity into a first impurity R1, a second impurity R2, and the PET solution P (step S12). The control device 30 then discharges the first impurity R1, the second impurity R2, and the PET solution P from the storage unit 20 (step S14). The control device 30 then causes the removal unit 26 to remove the third impurity R3 from the PET solution P (step S16).

[0060] This allows impurities to be appropriately removed from PET raw materials containing components other than PET, allowing the PET raw materials containing components other than PET to be recycled as raw materials for producing high-purity recycled PET products.

[0061] (About the polyester recycling system) Next, a polyester recycling system 100 according to the present disclosure will be described. FIG. 5 is a diagram showing an example of the configuration of a polyester recycling system according to the present disclosure. As shown in FIG. 5, the polyester recycling system 100 according to the present disclosure includes a separation system 1, a processing unit 40, a pellet production unit 50, and a molding unit 60. The separation system 1 is the same as that described above, and therefore a description thereof will be omitted. The processing unit 40, the pellet production unit 50, and the molding unit 60 will be described later.

[0062] (First embodiment) Next, the process of the first embodiment of the polyester recycling system 100 will be described with reference to FIG. 6. FIG. 6 is a flowchart showing the process flow of the first embodiment of the polyester recycling system according to the present disclosure. As shown in FIG. 6, in the polyester recycling system 100, PET raw material is input into a separation system 1, which removes foreign matter (step S101). The PET raw material from which the foreign matter has been removed is then introduced into a processing unit 40 of the polyester recycling system 100, where DMT is removed (step S102). The PET raw material from which DMT has been removed is then pelletized in a pellet production unit 50 (step S103). Optionally, the PET raw material is then solid-state polymerized in the pellet production unit 50 (step S104).

[0063] The solid-state polymerized recycled PET resin may be molded into recycled PET products in the molding unit 60. The process by which the molding unit 60 molds the recycled PET resin into recycled PET products will be described later. The processes in the processing unit 40 and the pellet production unit 50 of the polyester recycling system 100 will be specifically described below.

[0064] The processing unit 40 performs a predetermined process to remove DMT from the PET solution. Specifically, the PET solution is placed in a distillation furnace and heated to separate the DMT. Since the boiling point of DMT at atmospheric pressure is 288°C, heating the PET solution to a temperature of 288°C or higher evaporates the DMT, allowing the PET and DMT to be separated. The processing unit 40 may be realized, for example, by a separation tower, which separates the PET solution into a low-boiling component and a high-boiling component having a higher boiling point than the low-boiling component. For example, the PET solution may be heated to a predetermined temperature in the separation tower, with the gaseous component being the low-boiling component and the liquid component being the high-boiling component. The separation tower may be provided with an outlet pipe through which the low-boiling component is discharged.

[0065] The pellet production unit 50 pelletizes the PET solution from which DMT has been removed, thereby producing recycled PET pellets as recycled PET resin. The method for producing recycled PET pellets by the pellet production unit 50 may include a strand cutting method in which molten PET solution is slowly extruded from a nozzle into strands of a predetermined thickness, and the molten PET solution is brought into contact with cooling water using a slider or the like to cool the molten PET solution below its glass transition point, and then the strands are cut to produce pellets.

[0066] Alternatively, the pellet production unit 50 may pelletize the PET solution from which DMT has been removed and then solid-state polymerize the pellets to produce recycled PET pellets with an increased degree of polymerization. Solid-state polymerization of pellets may be performed, for example, through five steps: a crystallization step, a drying step, a heating step, a polymerization step, and a cooling step. The crystallization step is a step of generating uniform crystals in the pellets by raising the temperature of the pellets. The drying step is a step of drying the uniformly crystallized pellets using a low-dew-point gas. The heating step is a step of raising the temperature of the dried pellets to a polymerization temperature. The polymerization step is a step of solid-state polymerizing the pellets by maintaining them at the polymerization temperature for a predetermined time. The cooling step is a step of cooling the solid-state polymerized pellets to stop the solid-state polymerization of the pellets. Through these steps, recycled PET pellets with an increased degree of polymerization can be produced.

[0067] According to this, recycled PET pellets can be produced by removing DMT from the PET solution separated by the separation system 1 and then pelletizing it. Therefore, a polyester recycling system 100 can be provided that can effectively utilize the PET solution after impurities have been removed.

[0068] Second Embodiment Next, a polyester recycling system 100 according to a second embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart showing the flow of processing in the second embodiment of the polyester recycling system according to the present disclosure. As shown in Fig. 7, the processing in the second embodiment of the polyester recycling system 100 is the same as the processing in the first embodiment of the polyester recycling system 100 up to steps S201 and S202, and therefore description thereof will be omitted.

[0069] Next, in the pellet production unit 50 of the polyester recycling system 100, melt polymerization is performed using the PET solution from which DMT has been removed (step S203). Next, the pellet production unit 50 of the polyester recycling system 100 may pelletize the melt-polymerized PET solution (step S204) and then perform solid-state polymerization (step S205), similar to the first embodiment of the polyester recycling system 100. The processes from step S204 onwards are the same as those in the first embodiment of the polyester recycling system 100, and therefore will not be described here. Below, the processes in the pellet production unit 50 of the second embodiment of the polyester recycling system 100 will be specifically described.

[0070] The pellet production unit 50 melt-polymerizes the PET solution from which DMT has been removed. Melt polymerization is a polycondensation reaction that occurs in a molten state, and the reaction rate of the polycondensation reaction can be increased by increasing the temperature of the PET solution from which DMT has been removed. For example, the pellet production unit 50 can accelerate the melt polymerization reaction by heating the PET solution to 270°C or higher.

[0071] According to this, after removing DMT from the PET solution separated by the separation system 1, melt polymerization can be performed to produce recycled PET resin with a higher degree of polymerization. Therefore, a polyester recycling system 100 can be provided that can effectively utilize the PET solution after impurities have been removed. When EG is used instead of DMT, i.e., when monomer E is used instead of monomer D, the polyester recycling system 100 removes monomer E in the treatment unit 40. Furthermore, the treatment unit 40 is only required to remove and reduce the monomer from the PET solution, and some monomer may remain in the PET solution.

[0072] (Third embodiment) Next, a polyester recycling system 100 according to a third embodiment will be described with reference to Fig. 8. Fig. 8 is a flowchart showing the process flow of the third embodiment of the polyester recycling system according to the present disclosure. As shown in Fig. 8, the process of the second embodiment of the polyester recycling system 100 is the same as the process of the first embodiment of the polyester recycling system 100 up to step S301, and therefore description thereof will be omitted.

[0073] Next, in the processing unit 40 of the polyester recycling system 100, EG is added to the PET raw material from which foreign matter has been removed to cause transesterification (step S302). Next, in the third embodiment of the polyester recycling system 100, similar to the second embodiment of the polyester recycling system 100, melt polymerization (step S303), pelletization (step S304), and then selective solid-state polymerization (step S304) are sequentially performed.

[0074] The processing unit 40 of the third embodiment of the polyester recycling system 100, which performs processing different from that of the first and second embodiments of the polyester recycling system 100, will be specifically described below.

[0075] The processing unit 40 performs a predetermined process by adding EG to the PET solution. When EG is added to the PET solution, the remaining DMT and EG undergo a chemical reaction, resulting in transesterification. The final product is a compound called bis-hydroxyethyl terephthalate (BHET). BHET can be directly repolymerized into PET.

[0076] According to this system, recycled PET resin can be obtained by adding EG to the PET solution separated by the separation system 1 to cause transesterification, melt-polymerizing the PET solution, and pelletizing the PET solution. Therefore, a polyester recycling system 100 can be provided that can effectively utilize the PET solution after removing impurities.

[0077] (Fourth embodiment) Next, a polyester recycling system 100 according to a fourth embodiment will be described with reference to Fig. 9. Fig. 9 is a flowchart showing the flow of processing in the fourth embodiment of the polyester recycling system according to the present disclosure. As shown in Fig. 9, the processing in the fourth embodiment of the polyester recycling system 100 is the same as the processing in the first embodiment of the polyester recycling system 100 up to step S401, and therefore description thereof will be omitted.

[0078] Next, in the treatment unit 40 of the polyester recycling system 100, the PET raw material from which foreign matter has been removed is esterified by adding pure terephthalic acid (PTA) and EG (step S402). Next, in the fourth embodiment of the polyester recycling system 100, similar to the second and third embodiments of the polyester recycling system 100, melt polymerization (step S403), pelletization (step S404), and then, optionally, solid-state polymerization (step S405) are sequentially performed.

[0079] The processing of the processing unit 40 of the fourth embodiment of the polyester recycling system 100, which has a configuration different from that of the first to third embodiments of the polyester recycling system 100, will be specifically described below.

[0080] The processing unit 40 performs a predetermined process of adding PTA and EG to the PET solution. Specifically, the processing unit 40 adds PTA and EG to the PET solution after placing it in a reactor. The PET then reacts with the PTA and EG, resulting in esterification, a chemical reaction that directly converts carboxylic acid into ester.

[0081] According to this, PTA and EG are added to the PET solution separated by the separation system 1 to cause esterification, followed by melt polymerization and pelletization, thereby obtaining recycled PET resin. Therefore, a polyester recycling system 100 can be provided that can effectively utilize the PET solution after impurities have been removed.

[0082] (Regarding processing of molded parts) The following describes the process by which the molding unit 60 of the polyester recycling system 100 obtains various recycled PET products from recycled PET resin. The recycled PET products may be recycled PET containers, recycled PET fibers, recycled PET films, recycled PET sheets, etc.

[0083] The molding unit 60 may spin recycled PET resin to produce recycled polyester fiber. Spinning recycled polyester fiber using recycled PET resin may be performed, for example, by melt spinning. Melt spinning is a method in which recycled PET resin, a thermoplastic resin, is melted into a liquid, extruded through a nozzle with small holes, and cooled with air to solidify into a thread-like fiber. As the resin solidifies, it is pulled and wound up to produce a thin, long thread. The molding unit 60 may be realized, for example, by a spinning machine that extrudes liquid recycled PET resin through small holes to produce fiber, and a winding machine that pulls and winds up the fiber.

[0084] The molding unit 60 may stretch recycled PET resin to produce a film. In the film manufacturing method using the molding unit 60, a base film is first formed. The base film may be formed by an extrusion molding method in which molten recycled PET resin is extruded through a nozzle, or by a solution casting method in which a solution of recycled PET resin melted in a solvent to give it fluidity is poured onto a smooth-surfaced drum or a smooth stainless steel belt, and then heated to evaporate the solvent and form a film. Next, in the stretching process, the base film is stretched by processes such as longitudinal stretching in the film's travel direction, transverse stretching in the width direction, and diagonal stretching to change the size and thickness of the film.

[0085] The molding unit 60 may mold recycled PET containers using recycled PET resin. When using recycled PET resin to make recycled PET containers, the molding unit 60 may manufacture the recycled PET containers by pouring a molten PET solution into a mold that has been molded into the shape of the container by an injection molding machine, and then cooling the recycled PET resin.

[0086] This allows various recycled PET products to be obtained from recycled PET resin, and therefore provides a polyester recycling system 100 that can effectively utilize the PET solution after removing impurities.

[0087] (Composition and Effects) The polyester recycling system (polyester recycling system) 100 according to the first embodiment includes a dissolution section 12 that supplies a solution of monomers produced by decomposing polyester to a polyester raw material, which is a substance containing polyester, to produce a polyester solution in which the polyester from the polyester raw material is dissolved; a separation section that removes impurities, which are components other than polyester contained in the polyester raw material, from the polyester solution; a processing section 40 that performs a predetermined process on the polyester solution that has passed through the separation section; and a pellet production section 50 that produces recycled polyester pellets using the polyester solution that has been subjected to the predetermined process.

[0088] According to this configuration, after performing a predetermined process on the polyester solution separated by the separation system 1, the polyester solution can be used to produce recycled polyester pellets, and the recycled polyester pellets can be used to mold recycled polyester products. Therefore, it is possible to provide a polyester recycling system 100 that can effectively utilize the polyester solution after removing impurities.

[0089] The polyester recycling system 100 according to the second embodiment is the polyester recycling system 100 according to the first embodiment, and the processing unit 40 performs a process of removing the monomer D or the monomer E from the polyester solution as the predetermined process.

[0090] According to this configuration, recycled pellets can be produced by pelletizing the polyester solution after removing the monomers from the polyester solution separated by the separation system 1. Therefore, it is possible to provide a polyester recycling system 100 that can effectively utilize the polyester solution after removing the impurities.

[0091] The polyester recycling system 100 according to the third embodiment is the polyester recycling system 100 according to the first or second embodiment, and the pellet production unit 50 further performs solid-state polymerization on the pelletized recycled polyester resin.

[0092] According to this configuration, after removing the monomer from the polyester solution separated by the separation system 1, the pelletized recycled polyester resin can be solid-phase polymerized to produce recycled polyester pellets with an increased degree of polymerization. Therefore, it is possible to provide a polyester recycling system 100 that can effectively utilize the polyester solution after removing impurities.

[0093] The polyester recycling system 100 according to the fourth embodiment is the polyester recycling system 100 according to any one of the first to third embodiments, in which the processing unit 40 performs a process of removing monomers from the polyester solution as a predetermined process, and the pellet production unit 50 melt-polymerizes the polyester solution from which the monomers have been removed, and then pelletizes the melt-polymerized polyester solution.

[0094] According to this configuration, recycled pellets can be produced by pelletizing the melt-polymerized polyester solution after removing the monomers from the polyester solution separated by the separation system 1. Therefore, it is possible to provide a polyester recycling system 100 that can effectively utilize the polyester solution after removing the impurities.

[0095] The polyester recycling system 100 according to the fifth embodiment is the polyester recycling system 100 according to any one of the first to fourth embodiments, and the pellet production unit 50 further performs solid-state polymerization on the pelletized recycled polyester resin.

[0096] This configuration allows for the production of recycled polyester pellets with a higher degree of polymerization by solid-state polymerization of pelletized recycled polyester resin, thereby providing a polyester recycling system 100 that can effectively utilize the polyester solution after removing impurities.

[0097] The polyester recycling system 100 according to the sixth embodiment is the polyester recycling system 100 according to any one of the first to fifth embodiments, in which the processing unit 40 performs a predetermined process of adding ethylene glycol to the polyester solution to esterify it, and the pellet production unit 50 melt-polymerizes the transesterified polyester solution and then pelletizes the melt-polymerized polyester solution.

[0098] According to this configuration, recycled polyester pellets can be produced by adding ethylene glycol to the polyester solution separated by the separation system 1 to cause transesterification, melt-polymerizing the polyester solution, and then pelletizing the melt-polymerized polyester solution. Therefore, a polyester recycling system 100 can be provided that can effectively utilize the polyester solution after removing impurities.

[0099] The polyester recycling system 100 according to the seventh aspect is the polyester recycling system 100 according to any one of the first to sixth aspects, and the pellet production unit 50 further performs solid-state polymerization on the pelletized recycled polyester resin.

[0100] This configuration allows for the production of recycled polyester pellets with a higher degree of polymerization by solid-state polymerization of pelletized recycled polyester resin, thereby providing a polyester recycling system 100 that can effectively utilize the polyester solution after removing impurities.

[0101] The polyester recycling system 100 according to the eighth embodiment is the polyester recycling system 100 according to any one of the first to seventh embodiments, in which the processing unit 40 performs a predetermined process of adding high-purity terephthalic acid and ethylene glycol to the polyester solution to esterify it, and the pellet production unit 50 melt-polymerizes the esterified polyester solution and then pelletizes the melt-polymerized polyester solution to produce recycled polyester pellets.

[0102] According to this configuration, recycled polyester pellets can be produced by adding high-purity terephthalic acid and ethylene glycol to the polyester solution separated by the separation system 1 to esterify it, melt-polymerizing it, and then pelletizing the melt-polymerized polyester solution. Therefore, a polyester recycling system 100 can be provided that can effectively utilize the polyester solution after removing impurities.

[0103] The polyester recycling system 100 according to the ninth embodiment is the polyester recycling system 100 according to any one of the first to eighth embodiments, and the pellet manufacturing unit 50 further performs solid-state polymerization on the pelletized recycled polyester resin.

[0104] This configuration allows for the production of recycled polyester pellets with a higher degree of polymerization by solid-state polymerization of pelletized recycled polyester resin, thereby providing a polyester recycling system 100 that can effectively utilize the polyester solution after removing impurities.

[0105] The polyester recycling method according to the tenth aspect includes the steps of: supplying a solution of monomers produced by decomposing polyester to a polyester raw material, which is a substance containing polyester, to produce a polyester solution in which the polyester from the polyester raw material is dissolved; removing impurities, which are components other than polyester contained in the polyester raw material, from the polyester solution; and performing a predetermined process on the polyester solution from which the impurities have been removed.

[0106] According to this configuration, after performing a predetermined process on the polyester solution separated by the separation system 1, the polyester solution can be used to produce recycled polyester pellets, and the recycled polyester pellets can be used to mold a recycled polyester product. Therefore, it is possible to provide a polyester recycling method that can effectively utilize the polyester solution after removing impurities.

[0107] Although the embodiments of the present disclosure have been described above, the embodiments are not limited to the contents of these embodiments. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-described embodiments. [Explanation of symbols]

[0108] 1 Separation System 10 Raw material storage section 12 Melting part 13 Solid-liquid separation section 16 Foreign object collection section 20 Storage section 22 Discharge section 26 Removal section 30 Control device 100 Polyester Recycling System 40 Processing section 50 Pellet Manufacturing Department 60 Molding section D and E monomers M reaction solvent P PET solution Pd solution Pm PET raw material R impurity R1 First impurity R2 Second impurity R3 Third impurity

Claims

1. a dissolving section that supplies a solution of monomers produced by decomposing polyester to a polyester raw material, which is a substance containing polyester, to produce a polyester solution in which the polyester of the polyester raw material is dissolved; a separation section for removing impurities, which are components other than polyester contained in the polyester raw material, from the polyester solution; a processing unit that performs a predetermined process on the polyester solution that has passed through the separation unit; and a pellet manufacturing unit that manufactures recycled polyester pellets using the polyester solution that has been subjected to a predetermined process. Polyester recycling system.

2. the processing unit performs a process of removing the monomer from the polyester solution as the predetermined process. The polyester recycling system according to claim 1 .

3. The pellet production unit performs solid-state polymerization on the pelletized recycled polyester resin. The polyester recycling system according to claim 2.

4. the processing unit performs a process of removing the monomer from the polyester solution as the predetermined process. the pellet producing unit melt-polymerizes the polyester solution from which the monomer has been removed, and then pelletizes the melt-polymerized polyester solution. The polyester recycling system according to claim 1 .

5. The pellet production unit performs solid-state polymerization on the pelletized recycled polyester resin. The polyester recycling system according to claim 4.

6. the processing unit performs the predetermined treatment by adding ethylene glycol to the polyester solution to cause transesterification, The pellet production unit melt-polymerizes the transesterified polyester solution and then pelletizes the melt-polymerized polyester solution. The polyester recycling system according to claim 1 .

7. The pellet production unit performs solid-state polymerization on the pelletized recycled polyester resin. The polyester recycling system according to claim 6.

8. the processing unit performs the predetermined treatment by adding high-purity terephthalic acid and ethylene glycol to the polyester solution to esterify the polyester solution; The pellet production unit melt-polymerizes the esterified polyester solution and then pelletizes the melt-polymerized polyester solution. The polyester recycling system according to claim 1 .

9. The pellet production unit further performs solid-state polymerization on the pelletized recycled polyester resin. The polyester recycling system according to claim 8.

10. A step of supplying a solution of a monomer produced by decomposing a polyester to a polyester raw material, which is a substance containing a polyester, to produce a polyester solution in which the polyester of the polyester raw material is dissolved; removing impurities, which are components other than polyester contained in the polyester raw material, from the polyester solution; and performing a predetermined treatment on the polyester solution from which the impurities have been removed. How to recycle polyester.

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