Decomposing method and decomposing device for polymer material, and production method and production device for constitutional unit compound of polymer material

Abstract

To provide a method for thermally decomposing a polymer material that lowers the thermal decomposition temperature and enhances energy efficiency.SOLUTION: A decomposing method for a polymer material includes a radiation irradiation step in which a polymer material is irradiated with an electron beam or gamma rays, and a thermal decomposition step in which the polymer material irradiated with the electron beam or gamma rays is thermally decomposed. This decomposing method lowers the thermal decomposition temperature through the application of an electron beam or gamma rays to the polymer material, thereby achieving energy saving.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for decomposing a polymeric material, and also to a method and an apparatus for producing a structural unit compound of a polymeric material. [Background technology]

[0002] Fluorine-containing products such as fluororesin, pharmaceuticals, and liquid crystal displays are essential to our lives, but there are concerns about the depletion of fluorine, the raw material. In addition, the use of fluorine compounds such as fluorocarbons, perfluorooctanoic acid (PFOA), and perfluorooctane sulfonic acid (PFOS) is restricted due to concerns about environmental destruction and their effects on the human body. Therefore, technology is being developed to break down fluororesin and fluorine compounds into useful compounds through heat treatment and recycle them.

[0003] In addition, plastic materials such as polyethylene (PE), polypropylene (PP), and polystyrene (PS) are used in all commercial fields, generating large amounts of waste plastic products. These waste plastics flow into the ocean and become microplastics, raising concerns about their impact on the ecosystem. For this reason, methods for processing and effective use of waste plastics are being considered.

[0004] For example, Patent Document 1 describes a method for obtaining a fluororesin powder by irradiating an unmelted perfluoro melt-processed resin with radiation in the presence of oxygen so that the absorbed dose is 10 to 500 kGy. This method discloses that the obtained fluororesin powder is reused as a surface treatment agent, but there is a problem in that the applicable uses are narrow. Patent Documents 2 to 6 describe methods for obtaining tetrafluoroethylene by pyrolyzing a fluorine-based resin such as polytetrafluoroethylene. Furthermore, Non-Patent Document 1 discloses that waste plastics can be thermally decomposed and the resulting hydrocarbon material can be converted into hydrogen by steam reforming for effective use, and that the temperature for thermal decomposition of waste plastics can be lowered by using a nickel catalyst. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-342379 A [Patent Document 2] Special Publication No. 2012-504633 [Patent Document 3] Special Publication No. 2009-517454 [Patent Document 4] International Publication No. 2003 / 074456 [Patent Document 5] JP 2005-231984 A [Patent Document 6] Special Publication No. 2003-522747 [Non-patent literature]

[0006] [Non-Patent Document 1] Dingding Yao et al., “Co-precipitation, impregnation and so-gel preparation of Ni catalysts for pyrolysis-catalytic steam reforming of waste plastics,” Applied Catalysis B: Environmental, July 29, 2018, 239, pp. 565-577 Summary of the Invention [Problem to be solved by the invention]

[0007] In the methods described in Patent Documents 2 to 6, it is considered to reuse polymeric materials as structural unit compounds by pyrolyzing them. However, pyrolysis requires a high temperature of about 600°C, which is problematic as it requires a large amount of thermal energy. In addition, in the method described in Non-Patent Document 1, it is possible to reduce the thermal energy of pyrolysis by using a catalyst, but further energy saving is required.

[0008] Therefore, an object of the present invention is to provide a method for pyrolyzing a polymer material, which lowers the pyrolysis temperature and is excellent in energy efficiency. [Means for solving the problem]

[0009] As a result of intensive research into the above-mentioned problems, the present inventors have come to the discovery that, in a method for decomposing a polymeric material, the thermal decomposition temperature can be reduced by irradiating the polymeric material with an electron beam or gamma rays, and have completed the present invention. That is, the present invention relates to the following method and apparatus for decomposing a polymeric material, and method and apparatus for producing a structural unit compound of a polymeric material.

[0010] The method for decomposing a polymeric material of the present invention for solving the above problems is characterized by comprising a radiation irradiation step of irradiating the polymeric material with an electron beam or gamma rays, and a pyrolysis step of pyrolyzing the polymeric material irradiated with the electron beam or gamma rays. According to this method for decomposing a polymer material, by irradiating the polymer material with an electron beam or gamma rays, the thermal decomposition temperature in the thermal decomposition step of the polymer material is lowered, thereby providing a method for decomposing a polymer material that is excellent in energy efficiency.

[0011] Moreover, one embodiment of the method for decomposing a polymer material of the present invention is characterized by further comprising a catalyst addition step of adding a metal catalyst to the polymer material. According to this feature, since the pyrolysis temperature in the pyrolysis step of the polymer material can be further lowered, a method for decomposing a polymer material that is particularly excellent in energy efficiency can be provided.

[0012] In one embodiment of the method for decomposing a polymeric material of the present invention, the radiation exposure step is characterized in that the dose of electron beam or gamma ray is 4 MGy or more. According to this feature, since the pyrolysis temperature in the pyrolysis step of the polymer material can be further lowered, a method for decomposing a polymer material that is particularly excellent in energy efficiency can be provided.

[0013] In one embodiment of the method for decomposing a polymeric material of the present invention, the thermal decomposition step is characterized in that the heating temperature is 500° C. or lower. According to the method for decomposing polymeric materials of the present invention, the temperature of the pyrolysis step can be reduced, so that the decomposition process can be performed at 500° C. or less. By carrying out the pyrolysis step at 500° C. or less, it is possible to provide a method for decomposing polymeric materials that is particularly excellent in energy efficiency.

[0014] In one embodiment of the polymer material decomposition method of the present invention, the thermal decomposition step is characterized in that the polymer material is thermally decomposed by heat generated by irradiation with an electron beam in the radiation irradiation step. According to this feature, a separate heating process or heating device can be omitted, which has the effect of improving the efficiency of the work in the method for decomposing a polymer compound and simplifying the device configuration in the device for decomposing a polymer compound.

[0015] Moreover, one embodiment of the method for decomposing a polymeric material of the present invention is characterized in that the radiation irradiation step is carried out while the polymeric material is in a heated state. According to this feature, it is possible to provide a method for decomposing polymeric materials that is particularly excellent in energy efficiency, since the heating temperature and radiation dose can be reduced. In addition, since the radiation irradiation step and the pyrolysis step can be performed simultaneously, it is possible to obtain effects such as improved work efficiency.

[0016] In order to solve the above problems, the polymeric material decomposition device of the present invention is characterized by comprising a radiation irradiation section which irradiates a polymeric material with an electron beam or gamma rays, and a pyrolysis section which pyrolyzes the polymeric material irradiated with the electron beam or gamma rays. According to this polymer material decomposition apparatus, the polymer material is irradiated with electron beams or gamma rays, thereby lowering the thermal decomposition temperature in the thermal decomposition section of the polymer material, thereby providing a polymer material decomposition apparatus with excellent energy efficiency.

[0017] Moreover, one embodiment of the method for decomposing a polymer material of the present invention is characterized by including a catalyst adding section that adds a metal catalyst to the polymer material. According to this feature, the pyrolysis temperature in the pyrolysis section of the polymer material can be further lowered, so that a polymer material decomposition device that is particularly excellent in energy efficiency can be provided.

[0018] In order to solve the above problems, the method for producing a structural unit compound of a polymeric material of the present invention is a method for producing a structural unit compound from a polymeric material, and is characterized by comprising a radiation irradiation step of irradiating the polymeric material with an electron beam or gamma rays, and a pyrolysis step of pyrolyzing the polymeric material irradiated with the electron beam or gamma rays. According to this method for producing a structural unit compound of a polymer material, the polymer material is irradiated with an electron beam or gamma rays to lower the thermal decomposition temperature in the thermal decomposition step of the polymer material, so that a polymer material decomposition device with excellent energy efficiency can be provided. In addition, the polymer material is converted into monomers by thermal decomposition, and the monomers can be reused as raw materials for new polymer materials.

[0019] One embodiment of the method for producing a structural unit compound of a polymer material of the present invention is characterized by further comprising a catalyst addition step of adding a metal catalyst to the polymer material. According to this feature, since the pyrolysis temperature in the pyrolysis step of the polymer material can be further lowered, a method for producing a structural unit compound of a polymer material that is particularly excellent in energy efficiency can be provided.

[0020] In order to solve the above problems, the manufacturing apparatus for a structural unit compound of a polymeric material of the present invention is an apparatus for manufacturing a structural unit compound from a polymeric material, and is characterized in that it comprises a radiation irradiation section which irradiates the polymeric material with an electron beam or gamma rays, and a pyrolysis section which pyrolyzes the polymeric material irradiated with the electron beam or gamma rays. According to this apparatus for producing structural unit compounds of polymer materials, the thermal decomposition temperature in the thermal decomposition section of the polymer material is lowered by irradiating the polymer material with electron beams or gamma rays, so that it is possible to provide an apparatus for producing structural unit compounds of polymer materials with excellent energy efficiency. In addition, the polymer material is converted into monomers by thermal decomposition, which can be reused as raw materials for new polymer materials.

[0021] One embodiment of the apparatus for producing a structural unit compound of a polymer material according to the present invention is characterized in that it further comprises a catalyst adding section for adding a metal catalyst to the polymer material. According to this feature, the thermal decomposition temperature in the thermal decomposition section of the polymer material can be further lowered, so that it is possible to provide an apparatus for producing structural unit compounds of a polymer material that is particularly excellent in energy efficiency. Effect of the Invention

[0022] According to the present invention, in a method for pyrolyzing a polymer material, it is possible to provide a method for decomposing a polymer material which is excellent in energy efficiency by lowering the pyrolysis temperature. [Brief description of the drawings]

[0023] [Figure 1]1 is a graph showing the results of thermogravimetric analysis of PTFE after electron beam irradiation. Fig. 1(a) is a graph showing a comparison of the weight change between unirradiated PTFE and electron beam irradiated PTFE. Fig. 1(b) is a graph showing the relationship between the amount of electron beam irradiation and the 5% weight loss temperature. [Diagram 2] 2 is a graph showing the results of thermogravimetric analysis of PTFE / Ni catalyst after electron beam irradiation. Fig. 2(a) is a graph showing a comparison of weight change with and without Ni catalyst. Fig. 2(b) is a graph showing a comparison of 5% weight loss temperature with and without Ni catalyst. [Diagram 3] 1 is a graph showing the results of evaluating the effect of mixing order on the thermal decomposition behavior of a PTFE / Ni catalyst powder. [Figure 4] The graphs show the relationship between the heating temperature and the weight change of PTFE after irradiating the PTFE with an electron beam while heating the PTFE in a temperature-controllable thermostatic chamber. Figure 4(a) shows the weight change of the entire sample, and Figure 4(b) shows the weight change of PTFE. [Diagram 5] 1 is a graph showing the relationship between the electron beam irradiation time (dose) and the weight loss of PTFE in a method of irradiating with an electron beam while heating at 370° C. [Figure 6] 1 is a graph showing a specific example of a method for heating a polymer compound by irradiation with radiation. [Figure 7] FIG. 1 is a schematic diagram illustrating the configuration of a polymer material decomposition device (a production device for a structural unit compound of a polymer material) according to a first embodiment of the present invention. [Figure 8] FIG. 2 is a schematic diagram illustrating the configuration of a polymer material decomposition device (a production device for a structural unit compound of a polymer material) according to a second embodiment of the present invention. [Figure 9] FIG. 11 is a schematic diagram illustrating the configuration of an apparatus for decomposing a polymer material (an apparatus for producing a structural unit compound of a polymer material) according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, embodiments of the method and apparatus for decomposing a polymeric material, and the method and apparatus for producing a structural unit compound of a polymeric material according to the present invention will be described in detail. It should be noted that the method and apparatus for decomposing a polymeric material, and the method and apparatus for producing a constituent unit compound of a polymeric material described in the embodiments are merely examples for the purpose of explaining the present invention, and the present invention is not limited thereto. In addition, since the manufacturing method and manufacturing apparatus for the constituent unit compounds of polymer materials utilize the decomposition method and decomposition apparatus for polymer materials, the description thereof can be substituted for the description of the decomposition method and decomposition apparatus for polymer materials. Furthermore, the description of the features of the decomposition method and the decomposition apparatus for polymeric materials may be replaced with the description of the features of the corresponding decomposition apparatus and the decomposition method, respectively.

[0025] [Method and device for decomposing polymeric materials] The polymer material decomposition method (decomposition apparatus) of the present invention comprises a catalyst addition step (catalyst addition section) of adding a metal-based catalyst to the polymer material, a radiation irradiation step (radiation irradiation section) of irradiating the polymer material with electron beams or gamma rays, and a pyrolysis step (pyrolysis section) of pyrolyzing the polymer material irradiated with electron beams or gamma rays.

[0026] (polymer material) The polymeric material in the present invention is not particularly limited as long as it is a resin obtained by polymerizing a structural unit compound (monomer, oligomer, etc.), and examples thereof include hydrocarbon resins and fluororesins. Examples of the resin skeleton include polyolefins, polyesters, polyethers, polyamides, and polyurethanes. Since vinyl compounds can be obtained as structural unit compounds by the thermal decomposition of the present invention, polyolefins are preferred.

[0027] Examples of hydrocarbon resins include polyethylene (PE), high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyester resin, phenol resin, melamine resin, urea resin, epoxy resin, and polyurethane resin. Fluorine-based resins are resins that contain fluorine, and examples of such resins include polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polyvinylidene fluoride (PVDF), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinyl fluoride (PVF), polychlorotrifluoroethylene (PCTFE), and polychlorotrifluoroethylene-ethylene copolymer (ECTFE).

[0028] <Catalyst addition step> In the method for decomposing a polymer compound of the present invention, the thermal decomposition temperature of the polymer compound can be lowered by adding a metal catalyst. The order of the catalyst addition step and the radiation irradiation step is not particularly limited, but since the thermal decomposition temperature of the polymer compound is significantly reduced by irradiating the polymer compound with electron beams or gamma rays in the presence of a catalyst, it is preferable to carry out the catalyst addition step before or simultaneously with the radiation irradiation step. When the catalyst addition step is carried out after the radiation exposure step, the amount of raw material to be subjected to the radiation exposure step is reduced, so that the operation of the radiation exposure step can be simplified and the capacity of the radiation exposure unit can be reduced.

[0029] Examples of metals that can be used in the catalyst include scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), lanthanum (La), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), and oxides thereof. These metals can be used alone or in combination of two or more.

[0030] The metal catalyst may be supported on a carrier such as silica, alumina, silica-alumina, silica-calcia, zeolite, carbon, etc. to form a supported catalyst, or may be combined with a complex-forming organic compound to form a complex catalyst.

[0031] The amount of catalyst supported on the carrier is not particularly limited, but is, for example, 1 to 80% by mass in the supported catalyst. The lower limit is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 30% by mass or more, and particularly preferably 50% by mass or more. The upper limit is preferably 70% by mass or less.

[0032] The complex-forming organic compound is an organic compound that forms a complex with a metal atom by coordinating to the metal atom, and examples thereof include pyrrole, porphyrin, tetramethoxyphenylporphyrin, dibenzotetraazaannulene, phthalocyanine, choline, chlorine, phenanthroline, salcomine, benzimidazole, aminobenzimidazole, nicarbazin, diaminomaleonitrile, carbendazim, aminoantipyrine, and other complex-forming organic compounds, or polymers thereof. These complex-forming organic compounds can be used alone or in combination of two or more kinds.

[0033] When decomposing fluororesins such as polytetrafluoroethylene (PTFE), it is preferable to use a silica-alumina support, and a nickel / silica-alumina catalyst in which nickel is supported on a silica-alumina support is particularly preferable.

[0034] The ratio of the amount of metal catalyst added to the mass of the polymer compound (mass of metal catalyst / mass of polymer compound) is not particularly limited, but is, for example, 0.1 to 10. The lower limit is preferably 0.5 or more, and more preferably 0.8 or more. The upper limit is preferably 5 or less, and more preferably 2 or less. By setting it within this range, the mixability of the polymer compound and the metal catalyst becomes good, and the temperature of pyrolysis can be further reduced.

[0035] <Radiation exposure step> The polymer compound decomposition method of the present invention can lower the thermal decomposition temperature of the polymer compound by irradiating with an electron beam or gamma rays. The conditions for the radiation irradiation step are not particularly limited, but are, for example, room temperature (25°C) in an air atmosphere. The radiation irradiation step may be performed together with the thermal decomposition step while heating the polymer material. The method of irradiating with radiation while heating will be described in detail later.

[0036] The dose of electron beam or gamma ray is not particularly limited, but is, for example, 1 kGy to 20 MGy. The lower limit is preferably 100 kGy or more, more preferably 600 kGy or more, even more preferably 1 MGy or more, still more preferably 2 MGy or more, and particularly preferably 4 MGy or more. The upper limit is preferably 15 MGy or less. Irradiation with 4 MGy or more significantly reduces the temperature of pyrolysis.

[0037] The polymer compound may be heated by utilizing heat generated by irradiation with radiation. When electron beams are used as radiation, the polymer compound is easily heated to a high temperature. When gamma rays are used as radiation, the polymer compound is preferably housed in a thermostatic chamber that functions as a heat radiation suppression means, and the thermostatic chamber is preferably irradiated with gamma rays. This makes it possible to omit a separate heating step or heating device, which has the effect of improving the efficiency of the work in the decomposition method for polymer compounds and simplifying the device configuration in the decomposition device for polymer compounds, etc. In addition, heating by irradiation with radiation has the advantage of reducing energy loss because the polymer material can be directly heated.

[0038] When heating is performed by the radiation irradiation step, the irradiation conditions are not particularly limited, and may be, for example, continuous or intermittent irradiation. Intermittent irradiation has the effect of making it easier to control the temperature. Continuous irradiation has the effect of allowing heating in a short time.

[0039] The temperature of the polymer compound may be controlled by changing the current value of the electron beam. For example, it is preferable to control the current value of the electron beam to increase with the increase in the temperature of the polymer compound. Specifically, as shown in FIG. 6, when the temperature of the polymer compound is room temperature (25° C.) to 200° C., the current value of the electron beam is set to 0.5 to 1.5 mA (for example, 1 mA), when the temperature of the polymer compound is 100 to 300° C., the current value of the electron beam is set to 1.5 to 2.5 mA (for example, 2 mA), when the temperature of the polymer compound is 200 to 400° C., the current value of the electron beam is set to 2.5 to 4.5 mA (for example, 3 mA), when the temperature of the polymer compound is 300 to 500° C., the current value of the electron beam is set to 4.5 to 6.5 mA (for example, 5 mA), and when the temperature of the polymer compound is 400° C. or higher, the current value of the electron beam is set to 6.5 mA or higher (for example, 7 mA). This control increases the temperature of the polymer compound, allowing it to be thermally decomposed. The temperature for pyrolysis in the case of heating in the radiation irradiation step is the same as that in the pyrolysis step described below.

[0040] <Pyrolysis step> The polymer compound decomposition method of the present invention involves pyrolyzing the polymer material irradiated with electron beams or gamma rays in the radiation irradiation step. In the pyrolysis step, the polymer material may be decomposed in any state after decomposition as long as it can be decomposed, but from the viewpoint of recycling the polymer material, it is preferable to decompose it into the constituent unit compounds of the polymer material (monomers, oligomers, etc.). For example, when decomposing polytetrafluoroethylene (PTFE), it is preferable to decompose it to tetrafluoroethylene.

[0041] The temperature of the pyrolysis in the pyrolysis step is not particularly limited, but is, for example, 100 to 1000°C. From the viewpoint of improving energy efficiency, it is preferable to lower the pyrolysis temperature, and the upper limit is preferably 600°C or less, more preferably 500°C or less, even more preferably 300°C or less, and particularly preferably 200°C or less. From the viewpoint of promoting the thermal decomposition, it is preferable to increase the thermal decomposition temperature, and the lower limit is preferably 400° C. or higher, more preferably 500° C. or higher, and even more preferably 600° C. or higher.

[0042] The pyrolysis step may be performed while the polymer material is heated. Note that irradiation with radiation while heating is also called "heating irradiation". Heating irradiation can reduce the heating temperature and radiation dose, providing a method for decomposing polymeric materials that is particularly excellent in energy efficiency. In addition, the radiation irradiation step and the thermal decomposition step can be performed simultaneously, resulting in effects such as improved work efficiency.

[0043] The heating temperature in the heat irradiation is not particularly limited, but is, for example, 100 to 1000°C. From the viewpoint of improving energy efficiency, it is preferable to lower the pyrolysis temperature, and the upper limit is preferably 600°C or less, more preferably 400°C or less, even more preferably 300°C or less, and particularly preferably 200°C or less. From the viewpoint of promoting the thermal decomposition, it is preferable to increase the thermal decomposition temperature, and the lower limit is preferably 200° C. or higher, more preferably 300° C. or higher, and even more preferably 400° C. or higher.

[0044] The irradiation dose (dose) of electron beam or gamma ray in the heat irradiation is not particularly limited, but is, for example, 1 kGy to 20 MGy. The lower limit is preferably 100 kGy or more, more preferably 600 kGy or more, even more preferably 1 MGy or more, still more preferably 2 MGy or more, and particularly preferably 4 MGy or more. The upper limit is preferably 15 MGy or less. When irradiated with 2 MGy or more, decomposition due to irradiation occurs significantly.

[0045] [Production method and production device for structural unit compounds of polymer materials] The method and apparatus for producing a structural unit compound of a polymer material of the present invention is a method (apparatus) for producing a structural unit compound of a polymer material as a decomposition product obtained by the above-mentioned method and apparatus for decomposing a polymer material of the present invention. The catalyst addition step (catalyst addition section) of adding a metal-based catalyst to the polymeric material, the radiation irradiation step (radiation irradiation section) of irradiating the polymeric material with an electron beam or gamma rays, and the pyrolysis step (pyrolysis section) of pyrolyzing the polymeric material irradiated with the electron beam or gamma rays are the same as those in the polymeric material decomposition method and decomposition device.

[0046] <First embodiment> FIG. 7 is a schematic diagram illustrating the configuration of a polymer material decomposition apparatus (apparatus for producing structural unit compounds of polymer materials) 1A according to the first embodiment of the present invention. The polymer material decomposition device (production device for a structural unit compound of a polymer material) 1A of the first embodiment includes a radiation irradiation section 2 and a pyrolysis section 3. The polymer material P is irradiated with an electron beam or gamma rays by the radiation irradiation section 2, and is then pyrolyzed in the pyrolysis section 3 to the structural unit compound M.

[0047] <Second embodiment> FIG. 8 is a schematic diagram illustrating the configuration of a polymer material decomposition apparatus (apparatus for producing structural unit compounds of polymer materials) 1B according to the second embodiment of the present invention. The polymer material decomposition device (production device for structural unit compounds of polymer materials) 1B of the second embodiment includes a catalyst adding section 4, a radiation irradiating section 2, and a thermal decomposition section 3. The polymer material P is mixed with a catalyst in the catalyst adding section 4. Next, the polymer material P mixed with the catalyst is irradiated with an electron beam or gamma rays in the radiation irradiating section 2, and then thermally decomposed into structural unit compounds M in the thermal decomposition section 3.

[0048] <Third embodiment> FIG. 9 is a schematic diagram illustrating the configuration of a polymer material decomposition apparatus (apparatus for producing structural unit compounds of polymer materials) 1C according to the third embodiment of the present invention. The polymer material decomposition device (production device for the structural unit compounds of the polymer material) 1C of the third embodiment includes a catalyst addition section 4 and a radiation (electron beam) irradiation section 21. The polymer material P is mixed with the catalyst in the catalyst addition section 4. Next, the radiation (electron beam) irradiation section 21 irradiates the polymer material P mixed with the catalyst with an electron beam, whereby the polymer material P is heated simultaneously with the irradiation of the electron beam, and is decomposed into the structural unit compounds M. EXAMPLES

[0049] Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples.

[0050] (Investigation of the effect of radiation exposure on lowering the thermal decomposition temperature) A fluorine-based resin, polytetrafluoroethylene (PTFE) powder (Fujifilm Wako Pure Chemical Industries, Ltd.), was irradiated with a 2 MeV electron beam up to 15 MGy in air at room temperature. The residue was then subjected to thermogravimetric analysis (TGA) in argon gas to measure the weight loss associated with heating. The results for unirradiated PTFE and electron beam irradiated PTFE are shown in Figure 1(a). It is clear that the electron beam irradiated PTFE started thermal decomposition accompanied by weight loss at a lower temperature, and the 5% weight loss temperature, which is an index indicating the start of thermal decomposition, was 522°C for unirradiated PTFE and 160°C for electron beam irradiated PTFE. The 5% weight loss temperature changed depending on the amount of electron beam irradiation, saturating at about 160°C above 10 MGy (Figure 1(b)). The 100% weight loss temperature was 578°C for 4MGy and 573°C for 10MGy, whereas it was 595°C for the unirradiated case. Based on the results of Fig. 1(a), the amount of electricity required in the PTFE decomposition process was estimated. As a result, the amount of electricity required to decompose unirradiated PTFE was 155 kWh, whereas when electron beam irradiation was performed as a pretreatment, it was 66 kWh, and it was found that the method of the present invention can reduce the amount of electricity by 57% compared to the conventional method.

[0051] (Study on the effect of adding metal catalysts to lower the pyrolysis temperature) A powder (PTFE / Ni) made by mixing PTFE powder with nickel (Ni) catalyst powder (Nickel on silica / alumina, 65 wt% loading, Sigma-Aldrich) in a weight ratio of 1:1 was irradiated with a 2 MeV electron beam up to 10 MGy in air at room temperature, and the residue was subjected to thermogravimetric analysis (TGA) in argon gas to examine the weight change of the PTFE component. As shown in Figure 2 (a), even in the case of unirradiated PTFE / Ni, thermal decomposition begins at a lower temperature than unirradiated PTFE, but in the case of electron beam irradiated PTFE / Ni, thermal decomposition begins at an even lower temperature, and 80% is decomposed by 400°C. With the conventional method, there is no weight loss in this temperature range, which shows that the method of the present invention makes low-temperature treatment possible. Comparing the 5% weight loss temperatures, it was found that unirradiated PTFE: 522°C, electron beam irradiated PTFE: 160°C, unirradiated PTFE / Ni: 340°C, and electron beam irradiated PTFE / Ni: 103°C. It is known that fine particles of transition metals such as Ni, iron (Fe), and cobalt (Co) promote the thermal decomposition of plastic resins (see, for example, non-patent document 1). A similar effect was observed in the present invention, but it was found that the effect could be greatly enhanced by adding an electron beam irradiation treatment.

[0052] (Consideration of the order of catalyst addition step and radiation exposure step) The effect of the mixing order of Ni catalyst on the thermal decomposition behavior of PTFE powder was investigated. The methods examined were (1) mixing unirradiated PTFE with unirradiated Ni catalyst, (2) mixing unirradiated PTFE with electron beam irradiated Ni catalyst, (3) mixing electron beam irradiated PTFE with unirradiated Ni catalyst, (4) mixing electron beam irradiated PTFE with electron beam irradiated Ni catalyst, and (5) irradiating the mixture of PTFE and Ni catalyst with electron beam. Electron beam irradiation was performed in air at room temperature (25°C) with a dose of 10MGy, and the mixing ratio of PTFE and Ni catalyst was 1:1 by weight. From the results of TGA in argon gas shown in Figure 3, it was found that the temperature of thermal decomposition was most reduced by mixing PTFE and Ni catalyst in advance and irradiating them with electron beam. The weight residual ratio (%) in Figure 3 is the weight residual ratio relative to the entire sample including PTFE and Ni catalyst. The weight change of PTFE alone due to electron beam irradiation was examined, and it was found that a weight loss (gasification) of 43% occurred under the conditions of air, room temperature (25°C), and 10MGy. The weight change due to electron beam irradiation was then similarly examined for Ni catalyst alone and PTFE / Ni catalyst (weight ratio 1:1), and the results were -8% (weight increase due to oxidation) for Ni catalyst alone and 23% for PTFE / Ni catalyst. (43 x 0.5) + (-8 x 0.5) = 17.5, which makes it clear that simple additivity does not hold in the PTFE / Ni catalyst mixture, and gasification is promoted.

[0053] (Thermal decomposition of PTFE by heat irradiation) PTFE powder and Ni catalyst / PTFE mixed powder (mixture ratio 50wt:50wt) were placed in a temperature-controllable thermostatic chamber (container for high-temperature electron beam irradiation), and the weight loss of the samples was evaluated after irradiating them with electron beams up to 7.5MGy at a specified temperature under a dry air flow. The electron beam irradiation conditions were as follows. <Electron beam irradiation conditions> Acceleration voltage: 2 MeV, beam current: 1.5 mA (dose rate: 1.23 kGy / sec), irradiation time: 6098 sec

[0054] The results are summarized in Figure 4. Figure 4(a) shows the weight loss rate of the PTFE powder and the Ni-based catalyst / PTFE mixed powder relative to the entire sample. Figure 4(b) shows the weight loss rate of the Ni-based catalyst / PTFE mixed powder converted into the weight loss rate of the PTFE component.

[0055] The relationship between the irradiation temperature and the weight loss rate of the sample, shown in Figure 4(a), revealed that by irradiating the electron beam at 370°C, even PTFE without catalyst was gasified and disappeared almost 100%. From the results of conversion into the weight loss of the PTFE component shown in Fig. 4(b), it was found that the effect of adding a metal catalyst on gasification is not large in the case of heat irradiation. In other words, in the case of heat irradiation, the addition of a catalyst is not an essential requirement of the present invention.

[0056] (Relationship between electron beam irradiation time and weight loss of PTFE in pyrolysis by heating irradiation) The PTFE powder was placed in a temperature-controllable thermostatic chamber, and the weight loss of the sample was evaluated after irradiating it with an electron beam up to 7.5 MGy in a heated state at 370°C under a dry air flow. The electron beam irradiation conditions were as follows: <Electron beam irradiation conditions> Acceleration voltage: 2 MeV, beam current: 1.25 mA (dose rate: 1 kGy / sec), irradiation time: up to 7500 sec (dose: up to 7.5 MGy)

[0057] The results are summarized in Figure 5. 5, the weight loss after irradiation was 93% at 2.5 MGy, but it was revealed that irradiation of 5 MGy or more resulted in 100% gasification of non-catalyst-added PTFE. In the case of room temperature irradiation, the weight loss was only 43% even when irradiated up to 10 MGy, and it was found that decomposition can be promoted by heating irradiation. It was confirmed that when unirradiated PTFE was heated to 370°C at 10°C / min in air and held at that temperature for 2 hours, there was absolutely no weight loss (not shown). In other words, the weight loss upon irradiation at 370°C indicates decomposition due to the combined action of electron beam irradiation and heating.

[0058] Decomposition by heat irradiation has advantages over separate radiation and pyrolysis steps, such as not requiring a catalyst and being able to reduce the heating temperature required to achieve 100% weight reduction. [Industrial Applicability]

[0059] The polymer material decomposition method and decomposition device of the present invention can provide a processing method with low environmental impact by being applied to the processing of waste plastics and waste fluororesins. Furthermore, the method and apparatus for producing a structural unit compound of a polymer material of the present invention is capable of producing a structural unit compound from waste plastics and waste fluororesin, and can reuse the waste plastics and waste fluororesin as raw materials for new polymer materials. [Explanation of symbols]

[0060] 1A, 1B, 1C...Decomposition apparatus for polymeric material (production apparatus for structural unit compounds of polymeric material), 2...Radiation irradiation section, 21...Radiation (electron beam) irradiation section, 3...Pyrolysis section, 4...Catalyst addition section, P...Polymer material, M...Structural unit compound

Claims

1. a radiation exposure step of irradiating the polymer material with an electron beam or a gamma ray; A pyrolysis step of pyrolyzing the polymer material irradiated with electron beams or gamma rays; A method for decomposing a polymeric material, comprising:

2. The method for decomposing a polymer material according to claim 1 , further comprising a catalyst adding step of adding a metal catalyst to the polymer material.

3. 3. The method for decomposing a polymer material according to claim 1, wherein the radiation irradiation step is performed with an electron beam or gamma ray at a dose of 4 MGy or more.

4. 3. The method for decomposing a polymer material according to claim 1, wherein the heating temperature in the thermal decomposition step is 500° C. or less.

5. 3. The method for decomposing a polymer material according to claim 1, wherein the thermal decomposition step comprises thermally decomposing the polymer material with heat generated by irradiation with an electron beam in the radiation irradiation step.

6. 3. The method for decomposing a polymer material according to claim 1, wherein the thermal decomposition step comprises performing the radiation irradiation step while the polymer material is in a heated state.

7. a radiation irradiation unit that irradiates the polymer material with electron beams or gamma rays; a pyrolysis unit that pyrolyzes a polymer material irradiated with an electron beam or a gamma ray; A polymer material decomposition device comprising:

8. 8. The polymer material decomposition device according to claim 7, further comprising a catalyst adding section for adding a metal catalyst to the polymer material.

9. A method for producing a structural unit compound from a polymeric material, comprising the steps of: a radiation exposure step of irradiating the polymer material with electron beams or gamma rays; A pyrolysis step of pyrolyzing the polymer material irradiated with electron beams or gamma rays; A method for producing a structural unit compound of a polymer material, comprising:

10. The method for producing a structural unit compound of a polymer material according to claim 9, further comprising a catalyst addition step of adding a metal catalyst to the polymer material.

11. An apparatus for producing a structural unit compound from a polymer material, comprising: a radiation irradiation unit that irradiates the polymer material with electron beams or gamma rays; a pyrolysis unit that pyrolyzes a polymer material irradiated with an electron beam or a gamma ray; An apparatus for producing a structural unit compound of a polymer material, comprising:

12. 12. The apparatus for producing a structural unit compound of a polymer material according to claim 11, further comprising a catalyst adding section for adding a metal catalyst to the polymer material.

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