(METH)acrylic polymer regeneration device, method for regenerating (METH)acrylic polymer, and method for producing monomer having (METH)acrylic group

Abstract

To provide a (meth)acrylic polymer regeneration device, a (meth)acrylic polymer regeneration treatment method, and a (meth)acrylic acid ester production method with which it is possible to effectively suppress water from being mixed into a thermal decomposition product of a (meth)acrylic polymer.SOLUTION: A (meth)acrylic polymer regeneration device 100 includes a dehydration unit 1 that removes water contained in a (meth)acrylic polymer, and a thermal decomposition unit 2 that thermally decomposes the (meth)acrylic polymer from which water has been removed by the dehydration unit 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an apparatus for recycling a (meth)acrylic polymer, a method for recycling a (meth)acrylic polymer, and a method for producing a monomer having a (meth)acrylic group. [Background technology]

[0002] (Meth)acrylic polymers obtained by polymerizing monomers having a (meth)acrylic group have excellent transparency and weather resistance, and are therefore widely used as materials for components constituting automobile parts, signboards, display devices, etc.

[0003] Along with the recent rise in resource prices and growing awareness of environmental issues, there has been a growing trend to collect and recycle products (molded articles) containing (meth)acrylic polymers used for various applications as described above.

[0004] Methods for recycling molded articles containing (meth)acrylic polymers include, for example, material recycling, in which recovered molded articles are subjected to a molding process again to produce new molded articles; chemical recycling, in which recovered molded articles are thermally decomposed (depolymerized) to recover monomers having (meth)acrylic groups, and new molded articles are produced using these monomers; and thermal recycling, in which recovered molded articles are combusted and the resulting combustion energy is used as a direct heat source or as electricity converted by a generator.

[0005] (Meth)acrylic polymers are suitable for chemical recycling because the pyrolysis product, the monomer, can be recovered in high yield by heating at a relatively low temperature of about 300 to 500°C.

[0006] For example, Patent Document 1 describes a method for recovering a monomer having a (meth)acrylic group, which comprises heating a resin product containing a (meth)acrylic polymer in a heating furnace, cooling and liquefying the resulting gaseous pyrolysate, and then purifying the liquefied pyrolysate by distillation. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-321571 Summary of the Invention [Problem to be solved by the invention]

[0008] Since (meth)acrylic polymers have the property of absorbing water, the pyrolysate of the (meth)acrylic polymer may contain water. From the viewpoint of quality control of the pyrolysate of the (meth)acrylic polymer, it is desirable to prevent water from being mixed into the pyrolysate. One method for reducing the amount of water contained in the thermal decomposition product of a (meth)acrylic polymer is to remove water during the purification process of the thermal decomposition product of the (meth)acrylic polymer. However, if the amount of water to be removed is large, the amount of energy required for the purification process may increase. In view of the above circumstances, an object of one embodiment of the present disclosure is to provide a (meth)acrylic polymer recycling device, a (meth)acrylic polymer recycling method, and a (meth)acrylic acid ester manufacturing method that can effectively suppress the incorporation of water into a thermal decomposition product of a (meth)acrylic polymer. [Means for solving the problem]

[0009] Means for solving the above problems include the following embodiments. <1> a dehydration section for removing water contained in the (meth)acrylic polymer; a thermal decomposition section for thermally decomposing the (meth)acrylic polymer from which water has been removed in the dehydration section. <2> The dehydration section removes water contained in the solid (meth)acrylic polymer. <1> The playback device described in <3> The dehydration section removes water contained in the (meth)acrylic polymer in a softened or molten state. <1> The playback device described in <4> An extruder having at least one function of the dehydration section or the thermal decomposition section, <1> ~ <3> 10. The playback device according to claim 9, wherein: <5> a dehydration step of removing water contained in the (meth)acrylic polymer; a thermal decomposition step of thermally decomposing the (meth)acrylic polymer from which water has been removed in the dehydration step. <6> In the dehydration step, water contained in the solid (meth)acrylic polymer is removed. <5> The regeneration method described in <7> In the dehydration step, water contained in the (meth)acrylic polymer in a softened or molten state is removed. <5> The regeneration method described in <8> At least one of the dehydration step and the pyrolysis step is carried out using an extruder. <5> ~ <7> The regeneration method according to any one of the preceding claims. <9> a dehydration step of removing water contained in the (meth)acrylic polymer; and a thermal decomposition step of thermally decomposing the (meth)acrylic polymer from which water has been removed in the dehydration step. <10> In the dehydration step, water contained in the solid (meth)acrylic polymer is removed. <9> The manufacturing method described in <11> In the dehydration step, water contained in the (meth)acrylic polymer in a softened or molten state is removed. <9> The manufacturing method described in <12> At least one of the dehydration step and the pyrolysis step is carried out using an extruder. <9> ~ <11> The manufacturing method according to any one of the above. [Effects of the Invention]

[0010] According to the present disclosure, there are provided a (meth)acrylic polymer recycling device, a (meth)acrylic polymer recycling method, and a (meth)acrylic acid ester manufacturing method that can effectively suppress the incorporation of water into the thermal decomposition product of the (meth)acrylic polymer. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing an example of the configuration of a playback device. [Figure 2] FIG. 1 is a schematic diagram showing an example of the configuration of an extruder having the functions of a dehydration section and a thermal decomposition section. DETAILED DESCRIPTION OF THE INVENTION

[0012] First Embodiment The first embodiment of the present disclosure is a dehydration section for removing water contained in the (meth)acrylic polymer; and a thermal decomposition section for thermally decomposing the (meth)acrylic polymer from which water has been removed in the dehydration section.

[0013] The recycling apparatus of this embodiment converts a (meth)acrylic polymer supplied to the recycling apparatus into a monomer having a (meth)acrylic group, which is a thermal decomposition product thereof. A thermal decomposition product obtained from a water-containing (meth)acrylic polymer may contain water as an impurity. The boiling point of water is 100°C, which is slightly different from the boiling point of methyl methacrylate, 101°C. Therefore, if methyl methacrylate and water contained in the thermal decomposition product are separated from each other through a purification process, the number of distillations may increase, which may increase energy consumption. The regeneration device of this embodiment removes at least a portion of the water contained in the (meth)acrylic polymer before the thermal decomposition. The regeneration device of this embodiment can suppress the incorporation of water into the thermal decomposition product of the (meth)acrylic polymer with less energy consumption than when removing water contained in the thermal decomposition product in a purification step.

[0014] In the present disclosure, the term "(meth)acrylic polymer" refers to a polymer having structural units derived from a monomer having a (meth)acrylic group. In the present disclosure, "(meth)acrylic" includes acrylic, methacrylic, and combinations thereof.

[0015] The (meth)acrylic polymer may be a (meth)acrylic homopolymer or a (meth)acrylic copolymer. An example of the (meth)acrylic homopolymer is a (meth)acrylic homopolymer containing only monomer units derived from alkyl (meth)acrylate having an alkyl group having 1 to 4 carbon atoms. Examples of the (meth)acrylic copolymer include a (meth)acrylic copolymer in which the proportion of monomer units derived from alkyl (meth)acrylate having an alkyl group with 1 to 4 carbon atoms is 85% by mass or more and less than 100% by mass, and the proportion of monomer units derived from other vinyl monomers copolymerizable with the monomer units derived from alkyl (meth)acrylate having an alkyl group with 1 to 4 carbon atoms is more than 0% by mass and 15% by mass or less.

[0016] The "alkyl (meth)acrylate having an alkyl group with 1 to 4 carbon atoms" refers to a compound represented by, for example, CH2=C(CH3)COOR (wherein R is an alkyl group with 1 to 4 carbon atoms).

[0017] The vinyl monomer copolymerizable with an alkyl (meth)acrylate having an alkyl group with 1 to 4 carbon atoms is a monomer that is copolymerizable with an alkyl methacrylate having an alkyl group with 1 to 4 carbon atoms and has a vinyl group.

[0018] Examples of alkyl (meth)acrylates having an alkyl group of 1 to 4 carbon atoms include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, sec-butyl methacrylate, and isobutyl methacrylate. The alkyl methacrylate having an alkyl group of 1 to 4 carbon atoms is preferably methyl methacrylate.

[0019] Examples of vinyl monomers copolymerizable with alkyl (meth)acrylates having an alkyl group of 1 to 4 carbon atoms include methacrylate esters such as cyclohexyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, and monoglycerol methacrylate (excluding alkyl methacrylates having an alkyl group of 1 to 4 carbon atoms); methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, Examples of suitable monomers include acrylic acid esters such as 2-hydroxypropyl acrylate and monoglycerol acrylate; unsaturated carboxylic acids or anhydrides thereof such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, maleic anhydride and itaconic anhydride; nitrogen-containing monomers such as acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, diacetone acrylamide and dimethylaminoethyl methacrylate; epoxy group-containing monomers such as allyl glycidyl ether, glycidyl acrylate and glycidyl methacrylate; and styrene-based monomers such as styrene and α-methylstyrene.

[0020] The (meth)acrylic polymer may be polymethyl(meth)acrylate (PMMA or PMA), which is a polymer of methyl(meth)acrylate (MMA or MA).

[0021] The (meth)acrylic polymer supplied to the recycling device may be in the form of a molded product of the (meth)acrylic polymer. The type of molded product is not particularly limited and can be selected from known molded products such as cast molded products, extrusion molded products, and injection molded products.

[0022] The molded article of the (meth)acrylic polymer may consist of only the (meth)acrylic polymer, or may contain the (meth)acrylic polymer and a component different from the (meth)acrylic polymer. Examples of the component different from the (meth)acrylic polymer include polymers different from the (meth)acrylic polymer, such as polyvinyl chloride, polyolefin, and polyester, and additives. Examples of additives include fillers, colorants, ultraviolet inhibitors, and mold release agents.

[0023] The (meth)acrylic polymer supplied to the recycling device may be in the form of scrap or compressed material. In this disclosure, "scrap" refers to waste products collected after being used for a specific purpose, defective products and offcuts generated in the product manufacturing process, and pulverized waste products, defective products, and offcuts. "Compressed material" refers to a material obtained by compressing the material described as scrap. The scrap and compressed material may be adjusted in shape and size to be suitable for pyrolysis treatment.

[0024] The components included in the playback device of this embodiment will be described below.

[0025] (pyrolysis section) The regeneration device of this embodiment includes a thermal decomposition unit that thermally decomposes the (meth)acrylic polymer to convert it into a gaseous pyrolyzed product (hereinafter also referred to as pyrolysis gas). In the present disclosure, the thermal decomposition of a (meth)acrylic polymer means decomposing the (meth)acrylic polymer into monomers by heating.

[0026] As the thermal decomposition section, any device having a function of thermally decomposing a (meth)acrylic polymer can be used without any particular limitation. Processes used for the thermal decomposition of (meth)acrylic polymers include a molten metal bath process, a kneader process, a fluidized bed process, a microwave process, an extruder process, and the like.

[0027] The material of the thermal decomposition section is not particularly limited, and any known material can be used without any particular limitation. When the (meth)acrylic polymer supplied to the thermal decomposition section contains chlorine and water, hydrochloric acid may be generated by the reaction between the chlorine and water. Therefore, the (meth)acrylic polymer in the thermal decomposition section or the portion that comes into contact with the thermal decomposition gas is preferably made of a material that is highly corrosion-resistant. Examples of materials that are highly corrosion-resistant include Ti, Zr, Ta, and Hastelloy (registered trademark).

[0028] The conditions for carrying out the thermal decomposition of the (meth)acrylic polymer in the thermal decomposition section are not particularly limited, and can be set in consideration of the properties, composition, etc. of the (meth)acrylic polymer to be treated.

[0029] When a microwave process is used as the thermal decomposition method, for example, microwaves are irradiated from outside the reactor to thermally decompose the (meth)acrylic polymer. Unlike conventional heating processes, the use of microwaves allows energy to be applied directly and selectively to the target object at the speed of light. Plastics such as (meth)acrylic polymers generally have low microwave absorption capacity. For this reason, a component with high microwave absorption capacity may be added to the (meth)acrylic polymer to promote thermal decomposition.

[0030] From the viewpoint of the efficiency of the thermal decomposition process, the thermal decomposition section is preferably an extruder. In this disclosure, "extruder" refers to a device equipped with a mechanism that rotates a screw arranged inside a cylindrical member (cylinder) to melt raw materials fed from the upstream side of the cylinder and transport them downstream.

[0031] The type of extruder is not particularly limited, and a known twin-screw extruder or single-screw extruder can be used. From the viewpoint of efficiently carrying out the thermal decomposition of the (meth)acrylic polymer, the extruder is preferably a twin-screw extruder such as a twin-screw co-rotating extruder or a twin-screw counter-rotating extruder. As components of the extruder such as a cylinder and a screw, known components can be used without any particular limitation.

[0032] The pressure of the extruder is preferably 0.005 MPa to 1.5 MPa, more preferably 0.01 MPa to 0.3 MPa, from the viewpoint of preventing air from leaking into the system and pyrolysis gas from leaking out of the system.

[0033] From the viewpoint of thermal decomposition efficiency, the temperature inside the cylinder of the extruder can usually be set to 400° C. to 500° C. When the target of thermal decomposition is a pure (meth)acrylic polymer, the temperature is preferably 450° C. to 470° C.

[0034] From the viewpoint of stable operation of the extruder, the screw rotation speed of the extruder can usually be set to 500 rpm to 1500 rpm. When the target of thermal decomposition is a pure (meth)acrylic polymer, it is preferably 500 rpm to 1000 rpm.

[0035] The amount of (meth)acrylic polymer fed to the extruder varies depending on the scale of the extruder, but is usually 10 kg / hour to 5,000 kg / hour. For example, when the diameter of the extruder cylinder is 47 mm, the amount is preferably 40 kg / hour to 90 kg / hour.

[0036] (Dehydration section) The regeneration apparatus of this embodiment includes a dehydration section that removes water contained in the (meth)acrylic polymer. Hereinafter, the treatment for removing water contained in the (meth)acrylic polymer may also be referred to as "dehydration treatment of the (meth)acrylic polymer." In the present disclosure, the dehydration treatment of a (meth)acrylic polymer includes a treatment for partially removing water contained in the (meth)acrylic polymer and a treatment for completely removing water contained in the (meth)acrylic polymer.

[0037] The water content of the (meth)acrylic polymer before dehydration treatment is not particularly limited. For example, when the water content of the (meth)acrylic polymer before dehydration treatment is 5% by mass or more, 10% by mass or more, or 15% by mass or more, the effect of performing the dehydration treatment is greater. The dehydration treatment of the (meth)acrylic polymer is preferably carried out so that the water content of the (meth)acrylic polymer after the dehydration treatment is 1% by mass or less.

[0038] The (meth)acrylic polymer to be subjected to the dehydration treatment is not particularly limited as long as it is in a state before it becomes a pyrolysis gas, and may be in a solid state or in a softened or molten state.

[0039] Examples of a method for dehydrating a (meth)acrylic polymer in a solid state include a method of drying the (meth)acrylic polymer, a method of compressing the (meth)acrylic polymer, and a method of irradiating the (meth)acrylic polymer with electromagnetic waves. That is, the dehydration section may have at least one function selected from the group consisting of a function of drying the (meth)acrylic polymer, a function of compressing the (meth)acrylic polymer, and a function of irradiating the (meth)acrylic polymer with electromagnetic waves. When drying a (meth)acrylic polymer, evaporation of water contained in the (meth)acrylic polymer may be promoted by adjusting one or more of the environmental conditions surrounding the (meth)acrylic polymer, such as temperature, relative humidity, airflow, air pressure, etc. From the viewpoint of easily controlling the moisture content of the (meth)acrylic polymer after drying, a method employing at least one of adjusting the temperature or airflow is preferred, and a method employing both adjusting the temperature and airflow may also be employed. When the (meth)acrylic polymer is dried, the (meth)acrylic polymer may or may not be heated, but a heating method is more preferred. The (meth)acrylic polymer may be heated using a heating fuel.

[0040] A specific example of a method for compressing a (meth)acrylic polymer is a volume reduction and dehydration method. The pressure applied to the (meth)acrylic polymer is not particularly limited and can be adjusted taking into consideration the shape, water content, and shape after compression of the (meth)acrylic polymer to be compressed.

[0041] When the (meth)acrylic polymer contains a large amount of water (for example, the water content is 10% by mass or more), it is preferable to perform the dehydration treatment of the (meth)acrylic polymer by compression from the viewpoint of the efficiency of the dehydration treatment. In this case, the (meth)acrylic polymer may be further dried after being compressed and dehydrated.

[0042] Examples of a method for dehydrating a (meth)acrylic polymer in a softened or molten state due to plasticization include a method of separating water vapor from a (meth)acrylic polymer in a softened or molten state by heating or the like. That is, the dehydration section may have a function of melting the (meth)acrylic polymer. When separating water vapor from a softened or molten (meth)acrylic polymer, the softened or molten (meth)acrylic polymer may be kneaded to efficiently separate the water vapor. That is, the dehydration section may have a function of kneading the softened or molten (meth)acrylic polymer.

[0043] The dehydration treatment of the softened or molten (meth)acrylic polymer may be carried out using an extruder. The configuration of the extruder is not particularly limited, and any known extruder can be used.

[0044] When the dehydration treatment of the (meth)acrylic polymer is performed using an extruder, the extruder used for the dehydration treatment may be the same as the extruder used for the thermal decomposition of the (meth)acrylic polymer. That is, the recycling device of this embodiment may include an extruder having the function of a dehydration section and a different thermal decomposition section, or may include an extruder having the functions of a dehydration section and a thermal decomposition section. An example of an extruder having the functions of a dehydration section and a pyrolysis section is an extruder equipped, in this order: a feed port for feeding the (meth)acrylic polymer to be dehydrated and pyrolyzed into the extruder; a first outlet for discharging, to the extruder, water vapor contained in the (meth)acrylic polymer in a softened or molten state after being fed to the extruder; and a second outlet for discharging, to the extruder, pyrolysis gas obtained by pyrolysis of the (meth)acrylic polymer.

[0045] The first discharge outlet may be provided at any position between the raw material inlet and the second discharge outlet. From the viewpoint of suppressing mixing of steam and pyrolysis gas, it is preferable that the first outlet be disposed with a sufficient distance between it and the second outlet, and that the first outlet be oriented upward in the direction of gravity. The number of first discharge ports provided in one extruder may be one or more.

[0046] The discharge of water vapor from the first discharge port may be performed under negative pressure conditions. By discharging water vapor under negative pressure conditions, water vapor can be more reliably removed from the (meth)acrylic polymer in a softened or molten state. An example of a method for discharging water vapor from the first outlet under negative pressure conditions is to create a negative pressure inside a container connected to the first outlet and from which water vapor is collected using a vacuum pump or the like, making the pressure lower than the pressure inside the extruder.

[0047] The second outlet may be provided at any position in the region downstream of the first outlet. From the viewpoint of the efficiency of recovering the pyrolysis gas, the second outlet is preferably disposed near the downstream end of the pyrolysis section, and the second outlet is preferably oriented upward in the direction of gravity.

[0048] From the viewpoint of suppressing mixing of the water vapor and the pyrolysis gas, the extruder may be capable of independently adjusting the temperature of the region between the supply port and the first outlet and the temperature of the region between the first outlet and the second outlet. That is, the temperature of the region between the supply port and the first outlet and the temperature of the region between the first outlet and the second outlet can be set to different temperatures. It is preferable that the temperature of the region between the first outlet and the second outlet is set to a higher temperature than the temperature of the region between the supply port and the first outlet.

[0049] For example, the temperature of the region between the supply inlet and the first discharge outlet can be set to a temperature equal to or higher than the boiling point of water. In another embodiment, the temperature of the region between the supply inlet and the first discharge outlet may be adjusted to a temperature equal to or higher than the glass transition temperature of the (meth)acrylic polymer and lower than the temperature at which thermal decomposition of the (meth)acrylic polymer begins, and the temperature of the region between the first discharge outlet and the second discharge outlet may be adjusted to the temperature at which thermal decomposition of the (meth)acrylic polymer begins.

[0050] By adjusting the temperature of the region between the supply port and the first outlet to be equal to or higher than the boiling point of water, or equal to or higher than the glass transition temperature of the (meth)acrylic polymer and lower than the temperature at which thermal decomposition of the (meth)acrylic polymer begins, water vapor can be efficiently removed from the softened or melted (meth)acrylic polymer in that region, which effectively prevents water vapor from being mixed into the pyrolysis gas discharged from the second outlet. As a means for adjusting the temperature of the extruder, any known means can be used without any particular limitation.

[0051] The temperature of the extruder may be set in consideration of the pressure conditions inside the extruder. When the inside of the extruder is at normal pressure, the temperature of the region between the supply port and the first outlet is preferably 200°C or higher, and more preferably set in the temperature range of 230°C to 350°C. Furthermore, the temperature of the region between the first outlet and the second outlet is preferably set in the temperature range of 330°C to 500°C, and more preferably 350°C to 500°C. When the inside of the extruder is at negative pressure, the temperature range may also be within the above range.

[0052] In order to prevent water vapor from being mixed into the pyrolysis gas, the extruder may have a sealing member disposed between the first discharge port and the second discharge port. The sealing member is provided around the axis of the screw at a location between the first and second outlets of the cylinder of the extruder, for example, and can prevent water vapor remaining in the cylinder without being discharged from the first outlet from moving to the second outlet. The sealing member can be a screw element. Examples of the screw element include a seal ring, an element with a reverse flight structure, and an element with a reverse kneading structure. These elements form a resin pool by retaining or reversing the flow of resin inside the cylinder, making it easier to discharge water vapor from the first outlet. Commercially available sealing members can be used, taking into consideration the size and material.

[0053] From the viewpoint of efficiently discharging water vapor from the first discharge port while suppressing mixing of water vapor with the pyrolysis gas, the outer diameter of the seal member is preferably 90% to 99% of the inner diameter of the cylinder.

[0054] The extruder may include components other than those described above. For example, the extruder may further include a residue discharge port through which residue containing undecomposed components produced by the thermal decomposition treatment of the (meth)acrylic polymer is discharged to the outside of the extruder. The residue discharge port is preferably provided near the downstream end of the extruder, and is preferably oriented downward in the direction of gravity.

[0055] (Raw material supply department) The recycling device of the present disclosure may further include a raw material supply section that supplies a (meth)acrylic polymer as a raw material to the pyrolysis section. The method for supplying the raw materials is not particularly limited and can be selected from known methods. The raw material supply unit may include a processing device for processing the raw material, such as crushing the raw material, a detector for detecting foreign matter contained in the raw material, a measuring device for controlling the amount of raw material fed in, and the like. The dehydration section may be provided before the raw material supply section or after the raw material supply section.

[0056] (Pyrolysis gas treatment section) The regeneration device of the present disclosure may include a pyrolysis gas treatment unit that treats the pyrolysis gas generated in the pyrolysis unit. The method for treating the pyrolysis gas is not particularly limited and can be selected from known methods. As a means for treating the pyrolysis gas, known means such as a cooler for cooling and liquefying the pyrolysis gas, a purifier for increasing the purity of the monomer having a (meth)acrylic group contained in the pyrolysis product gas, and a tank for storing the monomer having a (meth)acrylic group liquefied by cooling can be used without any particular limitation, and can be combined as needed.

[0057] (Impurity gas treatment unit) The regeneration device of the present disclosure may include an impurity gas treatment section that treats the impurity gas generated in the thermal decomposition section. The method for treating the impurity gas is not particularly limited and can be selected from known methods. As a means for treating impurity gases, known means such as adsorbents, absorbents, metal catalysts, filters, etc. can be used without any particular limitation, and can be combined as necessary. Specific examples of the adsorbent include alumina, calcium oxide, calcium carbonate, iron oxide, iron hydroxide, carbon, zeolite, a complex of iron oxide and / or metallic iron with carbon, a complex of calcium oxide and carbon, and a complex of iron oxide and / or metallic iron with calcium carbonate and / or calcium oxide and carbon. A specific example of the absorbent is an aqueous solution containing a reducing agent and a base. By contacting this aqueous solution with the pyrolysis gas, impurities in the pyrolysis gas can be absorbed. The base is preferably selected from the group consisting of sodium hydroxide, sodium carbonate, and sodium bicarbonate (NaHCO3). The reducing agent is preferably selected from the group consisting of sodium sulfite, hydrogen peroxide, sodium thiosulfate, and sodium bisulfite (or hydrogen sulfite) (NaHSO3). The adsorbent or absorbent used in the impurity gas treatment section may be one type or two or more types.

[0058] From the viewpoint of increasing the efficiency of removing impurity gases from pyrolysis gases, it is preferable that the adsorbent or absorbent has a large contact area with the pyrolysis gas, and from this viewpoint, the adsorbent or absorbent is preferably in particulate form.

[0059] (cooling section) The regeneration device of the present disclosure may further include a cooling section that cools the pyrolysis gas discharged from the pyrolysis section. By providing the cooling section in the regeneration device, for example, it is possible to effectively prevent ignition or explosion of the pyrolysis gas discharged from the pyrolysis section.

[0060] The configuration of the cooling unit is not particularly limited as long as it can cool the pyrolysis gas. In one embodiment, for example, the cooling unit can cool the pyrolysis gas to a temperature equal to or higher than the condensation point of the pyrolysis gas and lower than the ignition point of the pyrolysis gas. Specifically, it is preferable that the cooling unit can cool the pyrolysis gas to a temperature equal to or higher than the condensation point of the pyrolysis gas containing methyl (meth)acrylate (about 100°C) and lower than the ignition point of the pyrolysis gas containing methyl (meth)acrylate (about 421°C). The temperature of the pyrolysis gas after being cooled by the cooling section is, for example, preferably 200°C to 410°C, and more preferably 300°C to 400°C.

[0061] In other embodiments of the cooling unit, a refrigerant may be in contact with the outer surface of the pipe through which the pyrolysis gas flows, or a refrigerant may pass through the inside of the pipe to cool the pyrolysis gas flowing outside the pipe. A specific example of the cooling unit is a double-pipe heat exchanger through which a refrigerant can flow. The refrigerant may be at least one selected from the group consisting of water, air, oil, molten salt, and water vapor.

[0062] (Residue storage area) The regeneration device of the present disclosure may further include a residue storage section that stores the residue discharged from the pyrolysis section. The method for storing the residue is not particularly limited and can be selected from known methods. The residue storage unit may include a processing device or the like that processes the residue into a disposable state. The method for storing the residue is not particularly limited and can be selected from known methods.

[0063] Second Embodiment A second embodiment of the present disclosure is a dehydration step of removing water contained in the (meth)acrylic polymer; and a thermal decomposition step of thermally decomposing the (meth)acrylic polymer from which water has been removed in the dehydration step.

[0064] According to the recycling method of the present embodiment, the (meth)acrylic polymer can be efficiently recycled while suppressing the inclusion of water in the pyrolyzed product obtained by pyrolyzing the (meth)acrylic polymer.

[0065] The (meth)acrylic polymer may be regenerated using the regeneration device of the first embodiment. That is, the dehydration step and the pyrolysis step may be performed using the dehydration section and the pyrolysis section of the regeneration device of the first embodiment.

[0066] According to the recycling method of the present embodiment, the (meth)acrylic polymer contained in the raw material is recycled into a monomer having a (meth)acrylic group by thermal decomposition. The reproduced monomer having a (meth)acrylic group is used, for example, as a raw material monomer for a (meth)acrylic polymer.

[0067] The monomer having a (meth)acrylic group obtained by the recycling method of this embodiment may contain methyl (meth)acrylate. The monomer having a (meth)acrylic group obtained by the recycling method of this embodiment may be a mixture of methyl (meth)acrylate and unavoidably contained monomers other than methyl (meth)acrylate (e.g., methyl isobutyrate, methyl propionate, methyl acrylate, etc.). In this case, the monomers other than methyl (meth)acrylate in the mixture may or may not be removed.

[0068] <Third embodiment> A third embodiment of the present disclosure is a dehydration step of removing water contained in the (meth)acrylic polymer; and a thermal decomposition step of thermally decomposing the (meth)acrylic polymer from which water has been removed in the dehydration step.

[0069] According to the production method of the present disclosure, a monomer having a (meth)acrylic group can be efficiently produced while suppressing the inclusion of water in the pyrolyzed product obtained by pyrolyzing a (meth)acrylic polymer.

[0070] The production of a monomer having a (meth)acrylic group may be carried out using the recycling apparatus of the first embodiment. That is, the dehydration step and the pyrolysis step for removing water contained in the (meth)acrylic polymer may be carried out using the dehydration section and the pyrolysis section of the recycling apparatus of the first embodiment.

[0071] According to the production method of this embodiment, a monomer having a (meth)acrylic group is obtained as a thermal decomposition product of a (meth)acrylic polymer contained in the raw material. The monomer having a (meth)acrylic group obtained as a pyrolyzate is used, for example, as a raw material monomer for a (meth)acrylic polymer.

[0072] The monomer having a (meth)acrylic group obtained by the production method of this embodiment is used, for example, as a raw material monomer for a (meth)acrylic polymer.

[0073] The monomer having a (meth)acrylic group obtained by the production method of this embodiment may contain methyl (meth)acrylate. The monomer having a (meth)acrylic group obtained by the production method of this embodiment may be a mixture of methyl (meth)acrylate and a monomer other than methyl (meth)acrylate that may be inevitably contained (e.g., methyl isobutyrate, methyl propionate, methyl acrylate, etc.). In this case, the monomer other than methyl (meth)acrylate in the mixture may or may not be removed.

[0074] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the components shown in each drawing can be modified without departing from the scope of the present disclosure.

[0075] FIG. 1 is a diagram schematically illustrating an example of the configuration of a playback device according to the first embodiment. As shown in FIG. 1, the regeneration device 100 includes a dehydration section 1, a pyrolysis section 2, and a pyrolysis gas treatment section 3.

[0076] In the dehydration section 1, water is removed from the (meth)acrylic polymer supplied to the regenerating apparatus 100. The (meth)acrylic polymer from which water is removed in the dehydration section 1 may be in a solid state or a liquid state. In the thermal decomposition section 2, the (meth)acrylic polymer from which water has been removed in the dehydration section 1 is thermally decomposed to obtain a thermal decomposition gas. In the pyrolysis gas treatment section 3, the pyrolysis gas obtained in the pyrolysis section 2 is liquefied, purified, stored, and so on. In the regeneration apparatus 100, there are no particular limitations on the specific configurations of the dehydration section 1 and the pyrolysis section 2. The regeneration apparatus 100 may include, for example, an extruder having the function of at least one of the dehydration section 1 and the pyrolysis section 2.

[0077] FIG. 2 is a diagram showing an example of the configuration of the dehydration section 1 and the pyrolysis section 2 included in the regeneration device 100, and is a schematic diagram showing an example of the configuration of an extruder having the functions of the dehydration section 1 and the pyrolysis section 2. As shown in FIG. 2, the extruder 10 includes a cylinder 10A and a screw 10B disposed inside the cylinder 10A. The extruder 10 is provided with a raw material inlet 12, a first outlet 14, and a second outlet 16 in this order. The (meth)acrylic polymer introduced through the raw material inlet 12 is softened or molten in a region R1 upstream of the first outlet, and water vapor separated from the softened or molten (meth)acrylic polymer is discharged from the first outlet 14. Next, the (meth)acrylic polymer is thermally decomposed in a region R2 upstream of the first outlet, and pyrolysis gas is discharged from the second outlet 16. [Explanation of symbols]

[0078] 100 playback equipment 1 Dehydration section 2 Pyrolysis section 3. Pyrolysis gas treatment section 10. Extruder 10A cylinder 10B screw 12 Raw material input port 14 1st outlet 16 2nd outlet

Claims

1. a dehydration section for removing water contained in the (meth)acrylic polymer; a thermal decomposition section for thermally decomposing the (meth)acrylic polymer from which water has been removed in the dehydration section.

2. The regenerating apparatus according to claim 1 , wherein the dehydration section removes water contained in the (meth)acrylic polymer in a solid state.

3. The recycling apparatus according to claim 1 , wherein the dehydration section removes water contained in the (meth)acrylic polymer in a softened or molten state.

4. The recycling apparatus according to any one of claims 1 to 3, further comprising an extruder having the function of at least one of the dehydration section and the pyrolysis section.

5. a dehydration step for removing water contained in the (meth)acrylic polymer; a thermal decomposition step of thermally decomposing the (meth)acrylic polymer from which water has been removed in the dehydration step.

6. The regeneration method according to claim 5, wherein the dehydration step removes water contained in the (meth)acrylic polymer in a solid state.

7. The regeneration method according to claim 5, wherein the dehydration step removes water contained in the (meth)acrylic polymer in a softened or molten state.

8. The regeneration method according to any one of claims 5 to 7, wherein at least one of the dehydration step and the pyrolysis step is carried out using an extruder.

9. a dehydration step for removing water contained in the (meth)acrylic polymer; and a thermal decomposition step of thermally decomposing the (meth)acrylic polymer from which water has been removed in the dehydration step.

10. The method according to claim 9 , wherein the dehydration step removes water contained in the (meth)acrylic polymer in a solid state.

11. The method according to claim 9 , wherein the dehydration step removes water contained in the (meth)acrylic polymer in a softened or molten state.

12. The method according to any one of claims 9 to 11, wherein at least one of the dehydration step and the pyrolysis step is carried out using an extruder.

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