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

Abstract

The present invention addresses the problem of providing 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.　The present invention relates to a (meth)acrylic polymer regeneration device 100 that 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.

Description

(Meth)acrylic polymer recycling device, (meth)acrylic polymer recycling method, and (meth)acrylic group-containing monomer manufacturing method

[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.

[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 (recycle) products (molded articles) containing (meth)acrylic polymers used for various applications as described above.

[0004] Methods for recycling molded articles containing a (meth)acrylic polymer 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 pyrolyzed monomers can be recovered in high yield by heating at a relatively low temperature of about 300°C to 500°C.

[0006] For example, Patent Document 1 describes a method for recovering a monomer having a (meth)acrylic group through a step of 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.

[0007] Japanese Patent Application Laid-Open No. 2003-321571

[0008] Because (meth)acrylic polymers have the property of absorbing water, pyrolysates of (meth)acrylic polymers may contain water. From the viewpoint of quality control of pyrolysates of (meth)acrylic polymers, it is desirable to prevent water from being mixed into the pyrolysates. One method for reducing the amount of water contained in the pyrolysates of (meth)acrylic polymers is to remove water during the purification process of the pyrolysates of (meth)acrylic polymers. However, if a large amount of water needs to be removed, the energy consumption 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 prevent water from being mixed into the pyrolysates of (meth)acrylic polymers.

[0009] Means for solving the above problems include the following embodiments. <1> A recycling device for a (meth)acrylic polymer, comprising: a dehydration section that removes water contained in the (meth)acrylic polymer; and a thermal decomposition section that thermally decomposes the (meth)acrylic polymer from which water has been removed in the dehydration section. <2> The recycling device according to <1>, in which the dehydration section removes water contained in the solid (meth)acrylic polymer. <3> The recycling device according to <1>, in which the dehydration section removes water contained in the softened or molten (meth)acrylic polymer. <4> The recycling device according to any one of <1> to <3>, comprising an extruder that has the functions of at least one of the dehydration section and the thermal decomposition section. <5> A recycling method for a (meth)acrylic polymer, comprising: a dehydration step that removes water contained in the (meth)acrylic polymer; and a thermal decomposition step that thermally decomposes the (meth)acrylic polymer from which water has been removed in the dehydration step. <6> The recycling method according to <5>, in which the dehydration step removes water contained in the solid (meth)acrylic polymer. <7> The recycling method according to <5>, wherein the dehydration step removes water contained in the (meth)acrylic polymer in a softened or molten state. <8> The recycling method according to any one of <5> to <7>, wherein at least one of the dehydration step and the thermal decomposition step is carried out using an extruder. <9> A method for producing a monomer having a (meth)acrylic group, comprising: a dehydration step for removing water contained in the (meth)acrylic polymer; and a thermal decomposition step for thermally decomposing the (meth)acrylic polymer from which water has been removed in the dehydration step. <10> The manufacturing method according to <9>, wherein the dehydration step removes water contained in the (meth)acrylic polymer in a solid state. <11> The manufacturing method according to <9>, wherein the dehydration step removes water contained in the (meth)acrylic polymer in a softened or molten state. <12> The manufacturing method according to any one of <9> to <11>, wherein at least one of the dehydration step and the thermal decomposition step is carried out using an extruder.

[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 production method that can effectively suppress the incorporation of water into the pyrolysis product of the (meth)acrylic polymer.

[0011] 1 is a schematic diagram showing an example of the configuration of a regeneration device.

[0023] FIG. 2 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.

[0012] <First embodiment> A first embodiment of the present disclosure is a (meth)acrylic polymer regeneration device including: a dehydration section that removes water contained in a (meth)acrylic polymer; and a thermal decomposition section that thermally decomposes the (meth)acrylic polymer from which water has been removed in the dehydration section.

[0013] The recycling device of this embodiment converts a (meth)acrylic polymer supplied to the recycling device into its pyrolysis product, a monomer having a (meth)acrylic group. The pyrolysis 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, attempting to separate the methyl methacrylate and water contained in the pyrolysis product through a purification process may increase energy consumption due to an increase in the number of distillations, etc. The recycling device of this embodiment removes at least a portion of the water contained in the (meth)acrylic polymer before it is pyrolyzed. The recycling device of this embodiment can suppress water contamination of the pyrolysis product of the (meth)acrylic polymer with less energy consumption than when removing water from the pyrolysis product through a purification process.

[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. Examples of (meth)acrylic homopolymers include (meth)acrylic homopolymers containing only monomer units derived from alkyl (meth)acrylates having an alkyl group with 1 to 4 carbon atoms. Examples of (meth)acrylic copolymers include (meth)acrylic copolymers in which the proportion of monomer units derived from alkyl (meth)acrylates having an alkyl group with 1 to 4 carbon atoms is 85% by mass or more but 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)acrylates having an alkyl group with 1 to 4 carbon atoms is more than 0% by mass but not more than 15% by mass.

[0016] The term "(meth)acrylic acid alkyl having an alkyl group having 1 to 4 carbon atoms" refers to, for example, CH ２ =C(CH ３ )COOR (wherein R is an alkyl group having 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 which is copolymerizable with an alkyl methacrylate having an alkyl group with 1 to 4 carbon atoms and which 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); acrylate esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and monoglycerol acrylate; unsaturated carboxylic acids 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 be composed of only the (meth)acrylic polymer, or may contain the (meth)acrylic polymer and a component other than the (meth)acrylic polymer. Examples of the component other than the (meth)acrylic polymer include polymers other than the (meth)acrylic polymer, such as polyvinyl chloride, polyolefin, and polyester, and additives. Examples of the 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] (Thermal Decomposition Unit) The recycling device of this embodiment includes a thermal decomposition unit. The thermal decomposition unit thermally decomposes the (meth)acrylic polymer to convert it into a gaseous pyrolyzate (hereinafter also referred to as pyrolysis gas). In the present disclosure, the thermal decomposition of the (meth)acrylic polymer refers to the decomposition of the (meth)acrylic polymer into monomers by heating.

[0026] The thermal decomposition section can be any device capable of thermally decomposing a (meth)acrylic polymer, and processes that can be used for the thermal decomposition of a (meth)acrylic polymer include the molten metal bath process, kneader process, fluidized bed process, microwave process, and extruder process.

[0027] The material of the thermal decomposition section is not particularly limited, and known materials can be used without particular limitation. When the (meth)acrylic polymer supplied to the thermal decomposition section contains chlorine and water, hydrochloric acid may be generated by reaction between the chlorine and water. Therefore, the part of the thermal decomposition section that comes into contact with the (meth)acrylic polymer or its pyrolysis gas is preferably made of a material with excellent corrosion resistance. Examples of materials with excellent corrosion resistance 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 the outside of 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 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 pyrolysis process, the pyrolysis section is preferably an extruder. In the present disclosure, the term "extruder" refers to a device having a mechanism for rotating a screw disposed inside a cylindrical member (cylinder) to melt raw materials introduced from the upstream side of the cylinder and transport the melted raw materials to the downstream side.

[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 constituting the extruder, such as a cylinder and a screw, known configurations can be used without 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 the efficiency of thermal decomposition, 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, the rotation speed is preferably 500 rpm to 1000 rpm.

[0035] The amount of the (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 cylinder of the extruder is 47 mm, the amount is preferably 40 kg / hour to 90 kg / hour.

[0036] (Dehydration Section) The regeneration device of this embodiment includes a dehydration section. The dehydration section removes water contained in the (meth)acrylic polymer. From the viewpoint of suppressing water contamination into the pyrolyzed product of the (meth)acrylic polymer, the dehydration section is preferably provided with a configuration different from that of the pyrolyzed section. Hereinafter, the process of removing water contained in the (meth)acrylic polymer is also referred to as "dehydration treatment of the (meth)acrylic polymer." In the present disclosure, the dehydration treatment of the (meth)acrylic polymer includes a process of partially removing water contained in the (meth)acrylic polymer and a process of completely removing water contained in the (meth)acrylic polymer.

[0037] The water content of the (meth)acrylic polymer before dehydration is not particularly limited. For example, when the water content of the (meth)acrylic polymer before dehydration 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 performed, for example, so that the water content of the (meth)acrylic polymer after dehydration 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 methods for dehydrating a solid (meth)acrylic polymer 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 unit 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 the (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, and atmospheric pressure. 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 the temperature and airflow may also be employed. When drying the (meth)acrylic polymer, 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 in consideration of the shape of the (meth)acrylic polymer to be compressed, the water content, the shape after compression, etc.

[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 the function of melting the (meth)acrylic polymer. When separating water vapor from a (meth)acrylic polymer in a softened or molten state, the (meth)acrylic polymer in a softened or molten state may be kneaded to efficiently separate the water vapor. That is, the dehydration section may have the function of kneading the (meth)acrylic polymer in a softened or molten state.

[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 functions of a dehydration section and a different thermal decomposition section, or 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 thermal decomposition section is an extruder having, in this order, a feed port for feeding the (meth)acrylic polymer to be dehydrated and thermally decomposed into the extruder, a first outlet for discharging water vapor contained in the (meth)acrylic polymer in a softened or molten state after being fed into the extruder, and a second outlet for discharging pyrolysis gas obtained by thermal decomposition of the (meth)acrylic polymer.

[0045] The first outlet may be provided at any position between the raw material inlet and the second outlet. From the viewpoint of suppressing mixing of steam and pyrolysis gas, the first outlet is preferably provided with a sufficient distance between it and the second outlet. The first outlet is preferably oriented upward in the direction of gravity. The number of first outlets 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 performing the discharge of water vapor under negative pressure conditions, it is possible to more reliably remove water vapor from the (meth)acrylic polymer in a softened or molten state. An example of a method for performing the discharge of water vapor from the first discharge port under negative pressure conditions is a method in which the internal pressure of a container connected to the first discharge port and from which water vapor is collected is made negative using a vacuum pump or the like, thereby making the internal pressure lower than the internal pressure of the extruder.

[0047] The second outlet may be located anywhere downstream of the first outlet. From the viewpoint of pyrolysis gas recovery efficiency, the second outlet is preferably located near the downstream end of the pyrolysis section. 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 temperature higher 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 may 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. As a result, mixing of water vapor into the pyrolysis gas discharged from the second outlet can be effectively prevented. Known means can be used to adjust the temperature of the extruder 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 discharge port 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 discharge port and the second discharge port 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 be within the above range.

[0052] To prevent water vapor from being mixed into the pyrolysis gas, the extruder may have a sealing member disposed between the first and second outlets. The sealing member is provided, for example, around the screw shaft at any location between the first and second outlets provided in the cylinder of the extruder. The sealing member can, for example, prevent water vapor remaining in the cylinder without being discharged from the first outlet from moving to the second outlet. Examples of the sealing member include the introduction of 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 in the cylinder, making it easier to discharge water vapor from the first outlet. Commercially available sealing members may be used, taking into consideration their 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. The residue discharge port discharges the residue containing undecomposed components generated by the thermal decomposition treatment of the (meth)acrylic polymer to the outside of the extruder. The residue discharge port is preferably provided near the downstream end of the extruder. The orientation of the residue discharge port is preferably downward in the direction of gravity.

[0055] (Raw material supply unit) The recycling device of the present disclosure may further include a raw material supply unit that supplies a (meth)acrylic polymer as a raw material to the pyrolysis unit. The method of supplying the raw material is not particularly limited and can be selected from known methods. The raw material supply unit may include a processing device that processes the raw material, such as crushing, a detector that detects foreign matter contained in the raw material, a measuring device that controls the amount of raw material input, etc. The dehydration unit described above may be provided before the raw material supply unit or after the raw material supply unit.

[0056] (Pyrolysis Gas Treatment Unit) The regeneration device of the present disclosure may be equipped with 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 that cools and liquefies the pyrolysis gas, a purifier that increases the purity of the monomer having a (meth)acrylic group contained in the pyrolysis product gas, and a tank that stores the monomer having a (meth)acrylic group liquefied by cooling can be used in combination as needed without particular limitation.

[0057] (Impurity Gas Treatment Unit) The regeneration device of the present disclosure may be equipped with an impurity gas treatment unit for treating impurity gas generated in the pyrolysis unit. The method for treating impurity gas is not particularly limited and can be selected from known methods. Known means for treating impurity gas, such as adsorbents, absorbents, metal catalysts, and filters, can be used in combination as needed without particular limitation. Specific examples of adsorbents 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. Specific examples of absorbents include 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 can be sodium hydroxide, sodium carbonate, or sodium bicarbonate (NaHCO ３ The reducing agent is preferably selected from the group consisting of sodium sulfite, hydrogen peroxide, sodium thiosulfate, and sodium bisulfite (or hydrogen sulfite) (NaHSO ３ 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 including the cooling section in the regeneration device, for example, it is possible to effectively prevent the pyrolysis gas discharged from the pyrolysis section from igniting or exploding.

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

[0061] In another embodiment 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 section) 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 section 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 method for regenerating a (meth)acrylic polymer, the method including: a dehydration step of removing water contained in the (meth)acrylic polymer; and a pyrolysis 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 by thermal decomposition into a monomer having a (meth)acrylic group. The recycled monomer having a (meth)acrylic group is used, for example, as a raw material monomer for the (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 monomers other than methyl (meth)acrylate that may be inevitably contained (such as 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 method for producing a monomer having a (meth)acrylic group, the method including: a dehydration step of removing water contained in a (meth)acrylic polymer; and a pyrolysis step of pyrolyzing 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 a 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 a raw material. The monomer having a (meth)acrylic group obtained as a thermal decomposition product 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). 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 regeneration device according to the first embodiment. As shown in Fig. 1, the regeneration device 100 includes a dehydration unit 1, a pyrolysis unit 2, and a pyrolysis gas treatment unit 3.

[0076] In the dehydration section 1, water is removed from the (meth)acrylic polymer supplied to the regeneration device 100. The (meth)acrylic polymer from which water is removed in the dehydration section 1 may be in a solid or liquid state. In the pyrolysis section 2, pyrolysis is carried out on the (meth)acrylic polymer from which water has been removed in the dehydration section 1 to obtain a pyrolysis gas. In the pyrolysis gas treatment section 3, the pyrolysis gas obtained in the pyrolysis section 2 is liquefied, purified, stored, etc. In the regeneration device 100, the specific configurations of the dehydration section 1 and the pyrolysis section 2 are not particularly limited. The regeneration device 100 may include, for example, an extruder having the function of at least one of the dehydration section 1 or the pyrolysis section 2.

[0077] FIG. 2 is a schematic diagram illustrating an example of the configuration of the dehydration section 1 or the pyrolysis section 2 included in the recycling apparatus 100, and is 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. When the extruder 10 functions as the dehydration section 1, the extruder 10 is provided with a raw material inlet 12 and a first outlet 14, in that order, and may optionally be provided with a second outlet 16. When the extruder 10 functions as the dehydration section 1, the (meth)acrylic polymer introduced through the raw material inlet 12 is softened or molten and transported from the tip of the extruder 10 to the pyrolysis section. In this case, the (meth)acrylic polymer 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. When the second outlet 16 is provided, water vapor may be discharged from the second outlet 16. When the extruder 10 is the pyrolysis section 2, it is provided with a raw material inlet 12 and a second outlet 16, and may optionally be provided with a first outlet 14. When the extruder 10 is the pyrolysis section 2, the (meth)acrylic polymer introduced through the raw material inlet 12 is pyrolyzed, and pyrolysis gas is discharged from the second outlet 16. As an example of one embodiment, when the extruder 10 is provided with the first outlet 14, the (meth)acrylic polymer may be softened or melted in a region R1 upstream of the first outlet, and water vapor separated from the softened or melted (meth)acrylic polymer may be discharged from the first outlet 14. In this case, the (meth)acrylic polymer is pyrolyzed in a region R2 upstream of the first outlet, and pyrolysis gas is discharged from the second outlet 16.

[0078] REFERENCE SIGNS LIST 100 Regeneration device 1 Dehydration section 2 Pyrolysis section 3 Pyrolysis gas treatment section 10 Extruder 10A Cylinder 10B Screw 12 Raw material inlet 14 First outlet 16 Second outlet

Claims

1. A (meth)acrylic polymer regeneration device comprising: a dehydration section that removes water contained in a (meth)acrylic polymer; and a thermal decomposition section that thermally decomposes 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 device according to any one of claims 1 to 3, comprising an extruder having the function of at least one of the dehydration section and the thermal decomposition section.

5. A method for regenerating a (meth)acrylic polymer, comprising: 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.

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 softened or molten (meth)acrylic polymer.

8. A 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 method for producing a monomer having a (meth)acrylic group, comprising: a dehydration step of removing water contained in a (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 softened or molten (meth)acrylic polymer.

12. The method of 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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