Gas separation membrane, gas separation device, and method for manufacturing gas separation membrane

Abstract

Provided is a gas separation membrane exhibiting high CO2 / N2 selectivity without being combined with other components. A gas separation membrane according to the present disclosure comprises a separation function layer containing a copolymer, wherein either the copolymer contains an ethylene oxide structure and a propylene oxide structure, the weight-average molecular weight of the copolymer being 13,000 or greater, or the copolymer is a random copolymer.

Description

Gas separation membrane, gas separation device, and method for manufacturing gas separation membrane

[0001] The present invention relates to a gas separation membrane, a gas separation apparatus, and a method for producing a gas separation membrane.

[0002] It is known to use polymer separation membranes as gas separation membranes for separating specific gas components from mixed gases. For example, Patent Document 1 discloses a gas separation membrane containing a polyethylene oxide-polypropylene oxide (PEO-PPO) copolymer as a component.

[0003] Korean Patent Publication No. 10-2022-0131454

[0004] However, the PEO-PPO copolymers used in the above-mentioned conventional techniques are sometimes liquid, and when the copolymers are used alone, they cannot be used to form films. In order to form films using liquid PEO-PPO copolymers, it was necessary to convert the copolymers into powder by combining them with other components. Therefore, it is not necessary to combine them with other components, and the structure is simpler and the film has a high carbon dioxide / nitrogen (CO ２ / N ２ Gas separation membranes that exhibit selectivity are desired.

[0005] One aspect of the present invention is to provide a high CO ２ / N ２ The present invention aims to provide a gas separation membrane that exhibits selectivity.

[0006] In order to solve the above problems, one embodiment of the present invention provides a gas separation membrane having a separation functional layer containing a copolymer, wherein the copolymer contains an ethylene oxide structure and a propylene oxide structure, and the weight average molecular weight of the copolymer is 13,000 or more.

[0007] In order to solve the above problems, a gas separation membrane according to one embodiment of the present invention is a gas separation membrane having a separation functional layer containing a copolymer, wherein the copolymer contains an ethylene oxide structure and a propylene oxide structure, and the copolymer is a random copolymer.

[0008] A method for producing a gas separation membrane according to one embodiment of the present invention is a method for producing a gas separation membrane containing a copolymer having an ethylene oxide structure and a propylene oxide structure and having a weight average molecular weight of 13,000 or more.

[0009] According to one aspect of the present invention, high CO ２ / N ２ It is possible to provide gas separation membranes that exhibit selectivity.

[0010] It is a cross-sectional view showing a gas separation membrane according to one embodiment of the present invention. It is a cross-sectional view showing a gas separation membrane according to another embodiment of the present invention. It is a schematic view showing a gas separation apparatus used in the examples.

[0011] Hereinafter, an example of an embodiment of the present invention will be described in detail, but the present invention is not limited thereto. Unless otherwise specified in this specification, "A to B" representing a numerical range means "A or more and B or less."

[0012] [1. Gas Separation Membrane] A gas separation membrane according to one embodiment of the present invention is a gas separation membrane having a separation functional layer containing a copolymer, wherein the copolymer contains an ethylene oxide structure and a propylene oxide structure, and the weight-average molecular weight of the copolymer is 13,000 or more. Alternatively, a gas separation membrane according to one embodiment of the present invention is a gas separation membrane having a separation functional layer containing a copolymer, wherein the copolymer contains an ethylene oxide structure and a propylene oxide structure, and the copolymer is a random copolymer.

[0013] As described above, the PEO-PPO copolymer used in the prior art may be liquid, and in order to form a membrane using this copolymer, it is necessary to convert the copolymer into a powder by combining it with other components. Furthermore, while powder PEO-PPO copolymers used in the prior art are also known, these copolymers have a low average molecular weight and are block copolymers. Block copolymers tend to crystallize easily and crack during membrane formation. As a result of studies by the present inventors, it has been found that by using, as the copolymer contained in the separation functional layer of a gas separation membrane, (i) a copolymer containing an ethylene oxide structure and a propylene oxide structure and having a weight-average molecular weight of 13,000 or more, or (ii) a copolymer containing an ethylene oxide structure and a propylene oxide structure and being a random copolymer, a high carbon dioxide / nitrogen (CO ) ratio can be achieved without combining it with other components. ２ / N ２ It has been found that a gas separation membrane exhibiting selectivity for carbon dioxide can be provided. A gas separation membrane according to one embodiment of the present invention can be used to selectively permeate carbon dioxide from a mixed gas containing carbon dioxide and nitrogen.

[0014] Facilitated transport membranes and dissolution-diffusion membranes are known as gas separation membranes. Facilitated transport membranes have excellent gas selectivity, but because they contain gas carriers, there is a concern that the gas carriers may leak out of the membrane during use, resulting in a decrease in gas separation ability. Dissolution-diffusion membranes are gas separation membranes that do not use gas carriers. Dissolution-diffusion membranes can selectively allow specific gas components to permeate by utilizing the difference in solubility of gas components contained in a mixed gas in the membrane material and the difference in diffusion coefficients of gas components contained in a mixed gas in the membrane material.

[0015] 1 and 2 are cross-sectional views schematically illustrating a gas separation membrane according to one embodiment of the present invention. The gas separation membrane 10 has a separation functional layer 15. The gas separation membrane 10 may be a solution-diffusion membrane. The separation functional layer 15 comprises a copolymer containing an ethylene oxide structure and a propylene oxide structure. Here, the ethylene oxide structure is a copolymer that is known in the technical field as a copolymer for separating carbon dioxide (CO ２ ) is known to have a high affinity for CO２ and nitrogen (N ２ ) from a mixed gas (raw material gas) containing CO ２ The gas separation membrane 10 can be suitably used for gas separation performed under temperature conditions of 20° C. or higher and 60° C. or lower, and can be used, for example, for gas separation of combustion exhaust gas generated in an incinerator.

[0016] According to the above configuration, carbon dioxide can be efficiently separated and appropriately reused, etc. Such an effect can contribute to achieving, for example, Goal 13 of the Sustainable Development Goals (SDGs) advocated by the United Nations, "Take urgent action to combat climate change."

[0017] 1 and 2, the gas separation membrane 10 may further include a porous support layer 11, and the separation function layer 15 may be provided on the porous support layer 11. The porous support layer 11 and the separation function layer 15 may be in direct contact with each other, or a gutter layer may be provided between the porous support layer 11 and the separation function layer 15. When the gas separation membrane 10 includes a gutter layer, it is preferable that the porous support layer 11 and the separation function layer 15 be in direct contact with the gutter layer.

[0018] As shown in Fig. 2, the gas separation membrane 10 may have a protective layer 12 on the side of the separation function layer 15 opposite the porous support layer 11 side. As shown in Fig. 2, the gas separation membrane 10 may further have a reinforcing layer 13 on the side of the porous support layer 11 opposite the separation function layer 15 side. The reinforcing layer 13 may be provided in direct contact with the porous support layer 11, or, for example, the reinforcing layer 13 and the porous support layer 11 may be heat-fused together. Alternatively, the reinforcing layer 13 and the porous support layer 11 may be attached to each other with a pressure-sensitive adhesive or adhesive.

[0019] <1-1. Separation Functional Layer> The separation functional layer 15 contains a copolymer containing an ethylene oxide structure and a propylene oxide structure. In this specification, the ethylene oxide (EO) structure is also referred to as an ethyleneoxy unit. The ethyleneoxy unit is a -(C ２ H ４ The ethyleneoxy unit may be polymerized alone to form a polyethylene oxide (PEO) structure. The polyethylene oxide structure is a structural unit represented by -(C２ H ４ O) ｎ Here, n represents an integer of 2 or more. n is usually 100 or more and 1,000,000 or less, and may be 400 or more and 200,000 or less, or 10,000 or more and 100,000 or less.

[0020] In this specification, the propylene oxide (PO) structure is also referred to as a propyleneoxy unit. A propyleneoxy unit is a -(C ３ H ６ The propyleneoxy unit may be polymerized alone to form a polypropylene oxide (PPO) structure. The polypropylene oxide structure is a structural unit represented by -(C ３ H ６ O) ｎ Here, n represents an integer of 2 or more. n is usually 100 or more and 1,000,000 or less, and may be 400 or more and 200,000 or less, or 10,000 or more and 100,000 or less.

[0021] The copolymer may be an ethylene oxide-propylene oxide (EO-PO) copolymer containing only ethylene oxide structures and propylene oxide structures. Alternatively, the copolymer may be a polyethylene oxide-polypropylene oxide (PEO-PPO) copolymer containing only polyethylene oxide structures and polypropylene oxide structures. The copolymer may further contain another structure in addition to the above structures. Examples of the other structure include a phenyl glycidyl ether (PhGE) structure, an allyl glycidyl ether (AGE) structure, and a butyl glycidyl ether (BGE) structure. For example, when the copolymer has a phenyl glycidyl ether (PhGE) structure as another structure, the copolymer may be an ethylene oxide-propylene oxide-phenyl glycidyl ether (EO-PO-PhGE) copolymer, a polyethylene oxide-polypropylene oxide-phenyl glycidyl ether (PEO-PPO-PhGE) copolymer, or the like. When the copolymer has an allyl glycidyl ether (AGE) structure as another structure, the copolymer may be an ethylene oxide-propylene oxide-allyl glycidyl ether (EO-PO-AGE) copolymer, a polyethylene oxide-polypropylene oxide-allyl glycidyl ether (PEO-PPO-AGE) copolymer, or the like.

[0022] In one embodiment of the present invention, the lower limit of the weight average molecular weight of the copolymer is 13,000 or more, preferably 30,000 or more, more preferably 50,000 or more, and even more preferably 100,000 or more. The upper limit of the weight average molecular weight of the copolymer may be, for example, 10,000,000 or less, or 5,000,000 or less. Here, in this specification, the weight average molecular weight of the copolymer refers to the weight average molecular weight of the copolymer contained in the separation functional layer of the obtained gas separation membrane. A weight average molecular weight of the copolymer within the above range is preferable from the viewpoint of the morphology of the copolymer and from the viewpoint that the copolymer has many amorphous portions. Note that the amorphous portions of the copolymer are CO ２ While the crystalline part of the copolymer has excellent selective permeability to CO ２ tend to have poor selective permeability.

[0023] In one embodiment of the present invention, the copolymer may be a random copolymer, such as an EO-PO random copolymer, an EO-PO-PhGE random copolymer, an EO-PO-AGE random copolymer, a PEO-PPO random copolymer, a PEO-PPO-PhGE copolymer, or a PEO-PPO-AGE copolymer.

[0024] The lower limit of the ratio of the ethylene oxide structure contained in the copolymer is preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more, based on 100 mol% of the structural units of the main chain of the copolymer. The upper limit of the ratio of the ethylene oxide structure contained in the copolymer may be, for example, 99 mol% or less, or 95 mol% or less. When the ratio of the ethylene oxide structure contained in the copolymer is within the above range, CO ２ This is preferable from the viewpoint of enhancing the affinity with the

[0025] The upper limit of the proportion of propylene oxide structures contained in the copolymer is preferably 17 mol% or less, more preferably 15 mol% or less, and even more preferably 10 mol% or less, based on 100 mol% of the structural units of the main chain of the copolymer. The lower limit of the proportion of propylene oxide structures contained in the copolymer may be, for example, 0.5 mol% or more, 1 mol% or more, or 5 mol% or more. If the proportion of propylene oxide structures contained in the copolymer is within the above range, it is preferable from the viewpoint of suppressing crystallization of the copolymer.

[0026] The copolymer may have a crosslinked structure. Examples of copolymers having a crosslinked structure include crosslinked EO-PO copolymers, crosslinked EO-PO-PhGE copolymers, crosslinked EO-PO-AGE copolymers, crosslinked PEO-PPO copolymers, crosslinked PEO-PPO-PhGE copolymers, crosslinked PEO-PPO-AGE copolymers, crosslinked EO-PO random copolymers, crosslinked EO-PO-PhGE random copolymers, crosslinked EO-PO-AGE random copolymers, crosslinked PEO-PPO random copolymers, crosslinked PEO-PPO-PhGE random copolymers, and crosslinked PEO-PPO-AGE random copolymers. The crosslinking method is not particularly limited, and examples include electron beam (EB) crosslinking, ultraviolet (UV) crosslinking, and chemical crosslinking by forming a covalent bond between reactive groups.

[0027] In a gas separation membrane according to another embodiment of the present invention, the gas separation membrane has a separation functional layer containing a copolymer, and the copolymer contains an ethylene oxide structure and a propylene oxide structure, and the copolymer is a random copolymer. In this embodiment, the weight average molecular weight of the copolymer is not particularly limited. The fact that the copolymer is a random copolymer contributes greatly to the copolymer having many amorphous portions. Therefore, by using a random copolymer, the gas separation membrane has excellent CO ２ For other configurations of the gas separation membrane according to this embodiment, the description in this specification can be used as appropriate.

[0028] In addition to the copolymer, the separation functional layer 15 may contain antioxidants, surfactants, fillers, crosslinking agents, liquid media, etc. (described below) contained in the composition for forming the separation functional layer 15. When the gas separation membrane of this embodiment is used as a solution-diffusion membrane, it is preferable that the separation functional layer 15 does not contain a gas carrier. Examples of gas carriers include substances that react reversibly with carbon dioxide, and specific examples include alkali metal carbonates, alkali metal bicarbonates, alkanolamines, alkali metal hydroxides, etc. "Not containing a gas carrier" means that the content of the gas carrier is less than 0.1 wt% relative to the total weight of the separation functional layer 15.

[0029] <1-2. Porous Support Layer> The porous support layer 11 can support the separation function layer 15. The porous support layer 11 can selectively pass the mixed gas supplied to the separation function layer 15 and the gas (e.g., CO ) contained in the mixed gas that selectively permeates the separation function layer 15. ２ It is preferable that the porous support layer 11 has high gas permeability so as not to act as a diffusion resistance for the gas. The porous support layer 11 can be formed from a resin material or an inorganic material. The porous support layer 11 may have a single-layer structure or a multi-layer structure.

[0030] Examples of resin materials constituting the porous support layer 11 include polyolefin resins such as polyethylene (PE) and polypropylene (PP); fluorine-containing resins such as polytetrafluoroethylene (PTFE), polyvinyl fluoride (PVF), and polyvinylidene fluoride (PVDF); polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate; polystyrene (PS), polyethersulfone (PES), polyphenylene sulfide (PPS), polysulfone (PSF), polyacrylonitrile (PAN), polyphenylene oxide (PPO), polyamide (PA), polyimide (PI), polyetherimide (PEI), polyetheretherketone (PEEK), high-molecular-weight polyester, heat-resistant polyamide, aramid, polycarbonate, and mixtures of two or more of these resin materials. Among these, polyolefin resins are preferred, and one or more of polyethylene and polypropylene are more preferred. Inorganic materials constituting the porous support layer 11 include metals, glass, ceramics, and the like.

[0031] The porous support layer 11 is not particularly limited as long as it is a porous body. The porous support layer 11 may be a porous body in the form of a sheet, such as a porous resin film, nonwoven fabric, woven fabric, foam, mesh, or net. The porous support layer 11 is preferably a porous resin film.

[0032] <1-3. Gutter Layer> The gas separation membrane 10 can have a gutter layer between the porous support layer 11 and the separation function layer 15. The gutter layer can prevent excessive penetration of the composition into the porous support layer 11 when the composition for forming the separation function layer 15 is applied onto the porous support layer 11, thereby enabling the separation function layer 15 to be successfully formed on the porous support layer 11. The gutter layer can also prevent the mixed gas (raw material gas) from leaking from defects that occur in the separation function layer 15.

[0033] The gas permeation rate of the gutter layer is preferably higher than that of the separation functional layer 15. The material for forming the gutter layer is not particularly limited. The gutter layer can be formed using a gas-permeable resin, and examples of such resins include silicone resin and amorphous fluororesin. The gutter layer may have a single-layer structure or a multi-layer structure.

[0034] <1-4. Protective Layer> In order to protect the separation functional layer 15, the gas separation membrane 10 can have a protective layer 12 on the side of the separation functional layer 15 opposite the porous support layer 11 side. The protective layer 12 can be formed from a resin material or an inorganic material, and can be formed from, for example, the materials described as materials that can be used for the porous support layer 11. The protective layer 12 may have a single-layer structure or a multi-layer structure.

[0035] <1-5. Reinforcement Layer> The gas separation membrane 10 may have a reinforcing layer 13 on the side of the porous support layer 11 opposite to the separation function layer 15 side. The reinforcing layer 13 may be provided to improve the handleability of the gas separation membrane 10 during production and to impart appropriate strength to the gas separation membrane 10. The reinforcing layer 13 may have a thickness greater than that of the porous support layer 11. The reinforcing layer 13 is configured to selectively permeate the mixed gas supplied to the separation function layer 15 and the gas (e.g., CO ) contained in the mixed gas that selectively permeates the separation function layer 15. ２The reinforcing layer 13 may have a high degree of gas permeability and porosity so as not to act as a diffusion resistance for the gas. The reinforcing layer 13 may be formed from a resin material or an inorganic material, and may be a nonwoven fabric, a woven fabric, or a net. The reinforcing layer 13 may be formed from, for example, the materials described as being usable for the porous support layer 11.

[0036] [2. Method for producing gas separation membrane] A method for producing a gas separation membrane 10 according to one embodiment of the present invention is a method for producing a gas separation membrane containing a copolymer having a weight average molecular weight of 13,000 or more, using a copolymer containing an ethylene oxide structure and a propylene oxide structure. Here, "using a copolymer containing an ethylene oxide structure and a propylene oxide structure" refers to using a copolymer containing an ethylene oxide structure and a propylene oxide structure as the copolymer contained in the coating solution prepared in the step described in detail below. Explanation of matters already explained in [1. Gas separation membrane] above will be omitted below.

[0037] A manufacturing method according to one embodiment of the present invention may include a step of forming a separation functional layer 15 on a porous support layer 11. This step may include a step of applying a coating liquid containing the copolymer and a liquid medium for dissolving or dispersing the copolymer onto the porous support layer 11. The layer formed by applying the coating liquid may become the separation functional layer 15. The manufacturing method may also include a step of subjecting the porous support layer 11 to a corona treatment before applying the coating liquid onto the porous support layer 11. Furthermore, the manufacturing method may also include a step of filtering the composition constituting the coating liquid before applying the coating liquid onto the porous support layer 11. Filtering the composition can remove air bubbles, insoluble matter, and the like contained in the resulting coating liquid. This can prevent defects from occurring in the layer of the coating liquid and the separation functional layer formed from that layer when the coating liquid is applied onto the porous support layer 11.

[0038] The liquid medium is not particularly limited as long as it is a liquid medium capable of dissolving or dispersing the copolymer. Examples of the liquid medium include protic polar solvents such as water, alcohols such as methanol, ethanol, 1-propanol, and 2-propanol; nonpolar solvents such as toluene, xylene, and hexane; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and aprotic polar solvents such as N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and acetonitrile. One type of liquid medium may be used alone, or two or more types may be used in combination as long as they are compatible. Among these, liquid media containing at least one selected from the group consisting of water, and alcohols such as methanol, ethanol, 1-propanol, and 2-propanol are preferred, and liquid media containing water are more preferred.

[0039] In addition to the copolymer and the liquid medium, the coating liquid may contain a surfactant, a filler, a crosslinking agent, a polymerization initiator, an antioxidant, etc. The surfactant is not particularly limited and may be an anionic surfactant, a cationic surfactant, an amphoteric surfactant, or a nonionic surfactant. Examples of the surfactant include known surfactants such as fluorine-based surfactants and silicone-based surfactants. One type of surfactant may be used alone, or two or more types may be used in combination. By including a surfactant in the coating liquid, when the coating liquid is applied to a porous support layer, the wettability between the coating liquid and the coating surface can be improved, thereby preventing unevenness in the film thickness of the separation functional layer 15.

[0040] The filler may be an inorganic filler such as zeolite, silica, or carbon, an organic filler such as resin particles, or an organic-inorganic filler such as a metal-organic framework (MOF), or two or more of these may be used.

[0041] Examples of crosslinking agents include acrylic acid esters. The coating liquid may not contain a crosslinking agent for crosslinking the copolymer. "Not containing a crosslinking agent" means that the content of the crosslinking agent is less than 0.1 wt% relative to the total weight of the copolymer in the coating liquid. When the coating liquid contains a crosslinking agent, the content of the crosslinking agent may be 0.1 wt% or more and 50 wt% or less, 1 wt% or more and 20 wt% or less, or 1 wt% or more and 10 wt% or less relative to the total weight of the copolymer in the coating liquid.

[0042] Examples of the polymerization initiator include photopolymerization initiators and thermal polymerization initiators. Examples of the photopolymerization initiator include, but are not limited to, lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone. Examples of the thermal polymerization initiator include, but are not limited to, 2,2'-azobis(2-methylpropionamidine) dihydrochloride and 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride. One type of polymerization initiator may be used alone, or two or more types may be used in combination.

[0043] Examples of antioxidants include vitamin E (tocopherol), Irganox 1520 (manufactured by BASF Japan), 2,6-di-t-butyl-4-s-butylphenol, Irganox 1076 (manufactured by BASF Japan), 4,6-bis(octylthiomethyl)-o-cresol, tris(2,4-di-t-butylphenyl)phosphite, Adekastab HP-10 (manufactured by ADEKA Corporation), Irgafos 38 (manufactured by BASF Japan), triisodecyl phosphite, tris(2-ethylhexyl)phosphite, tri-o-tolyl phosphite, tris(2,4-di-tert-butylphenyl)phosphite, 2-methyl-4,6-bis[(n-octylthio)methyl]phenol, and stearyl Examples of antioxidants include 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, 2,4-bis[(dodecylthio)methyl]-6-methylphenol, etc. One antioxidant may be used alone, or two or more antioxidants may be used in combination.

[0044] The content of the copolymer in the coating liquid may be 0.1% by weight or more and 70% by weight or less, 1.0% by weight or more and 60% by weight or less, or 1.5% by weight or more and 55% by weight or less, based on 100% by weight of the total weight of the coating liquid.

[0045] When the gas separation membrane 10 has a gutter layer, the manufacturing method may include a step of forming the gutter layer on the porous support layer 11. The gutter layer can be formed by, for example, applying a material for forming the gutter layer to the porous support layer 11. When the gutter layer is formed on the porous support layer 11, the coating liquid is applied to the side of the porous support layer 11 on which the gutter layer is formed.

[0046] There are no particular limitations on the method for applying the coating liquid onto the porous support layer 11. Examples of the coating method include a method using an applicator, spin coating, bar coating, die coating, blade coating, air knife coating, gravure coating, roll coating, spray coating, dipping, comma roll coating, kiss coating, screen printing, and inkjet printing. The amount of coating liquid is such that the basis weight (amount of solids per unit area) is 1 g / m. ２ More than 1000g / m ２ The range is preferably 5 g / m ２ 750g / m or more ２ More preferably, the range is 10 g / m ２ More than 500g / m ２ The weight per unit area can be controlled by the coating film formation speed (for example, the conveying speed of the porous support layer), the concentration of the coating liquid, the discharge amount of the coating liquid, and the like.

[0047] When gas separation membrane 10 has reinforcing layer 13, it is preferable to prepare a laminated support of reinforcing layer 13 and porous support layer 11, and apply the coating liquid to the porous support layer 11 side of this laminated support.

[0048] The manufacturing method may include a step of removing the liquid medium from the coating liquid. For example, the liquid medium can be removed by air drying, forced air drying, heat drying, etc. When the gas separation membrane 10 has a protective layer 12, the protective layer 12 may be laminated before the step of removing the liquid medium from the coating liquid, or after the step of removing the liquid medium from the coating liquid.

[0049] The production method may include a step of irradiating the coating film obtained in the step with electron beams (EB) or ultraviolet rays (UV) after the step of applying the coating liquid to the porous support layer 11. This allows the copolymer to be crosslinked by electron beams or ultraviolet rays, respectively.

[0050] The electron beam irradiation dose is preferably 10 kGy or more, more preferably 15 kGy or more and 400 kGy or less, even more preferably 20 kGy or more and 400 kGy or less, and may be 30 kGy or more and 350 kGy or less, or 40 kGy or more and 300 kGy or less.

[0051] The irradiation intensity of ultraviolet light is 10 to 500 mW / cm ２ and preferably 50 to 400 mW / cm ２ and more preferably 75 to 400 mW / cm ２ and more preferably 90 to 360 mW / cm ２ is.

[0052] The cumulative amount of ultraviolet light is 50 to 3000 mW / cm ２ and preferably 100 to 1000 mW / cm ２ and more preferably 100 to 500 mW / cm ２ and more preferably 150 to 400 mW / cm ２ is.

[0053] The coating liquid applied to the porous support layer 11 may be irradiated with electron beams or ultraviolet rays from the porous support layer 11 side, or from the coating liquid side, or both. The electron beams or ultraviolet rays may be irradiated in an air atmosphere, or in an atmosphere of an inert gas such as nitrogen gas, argon gas, or helium gas.

[0054] 3. Gas Separation Apparatus The gas separation apparatus 100 can be equipped with the above-described gas separation membrane 10. The gas separation apparatus 100 is advantageous for long-term operation because it is equipped with the gas separation membrane 10. For example, the gas separation apparatus 100 of this embodiment can be suitably used to separate combustion exhaust gas generated in an incinerator.

[0055] The gas separation membrane 10 can be incorporated into the gas separation apparatus 100 as a gas separation membrane element of a known form, such as a spiral type, flat membrane type, pleated type, or plate-and-frame type. The gas separation membrane element may have a laminate in which a feed-side gas flow path member through which a raw gas (mixed gas) and non-permeate gas flow, and a permeate-side gas flow path member through which a permeate gas flows are stacked on the gas separation membrane 10. The gas separation membrane element can have a sealing portion to prevent mixing of the raw gas and non-permeate gas with the permeate gas.

[0056] In addition to the gas separation membrane 10 (a gas separation membrane element having the gas separation membrane 10), the gas separation device 100 can have a supply section for supplying a mixed gas to the gas separation membrane 10, a permeable gas discharge section for discharging the permeable gas that has permeated the gas separation membrane 10, and a non-permeable gas discharge section for discharging the non-permeable gas that has not permeated the gas separation membrane 10.

[0057] The operating temperature of the gas separation apparatus 100 may be 20°C or higher and 60°C or lower, preferably 30°C or higher and 55°C or lower, and more preferably 35°C or higher and 50°C or lower.

[0058] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0059] An embodiment of the present invention may include the following features.

[0060] [1] A gas separation membrane having a separation functional layer containing a copolymer, wherein the copolymer contains an ethylene oxide structure and a propylene oxide structure, and the copolymer has a weight average molecular weight of 13,000 or more.

[0061] [2] The gas separation membrane according to [1], wherein the copolymer is a random copolymer.

[0062] [3] The gas separation membrane according to [1] or [2], wherein the ratio of the propylene oxide structure contained in the copolymer is 17 mol % or less in 100 mol % of the structural units of the main chain of the copolymer.

[0063] [4] The gas separation membrane according to any one of [1] to [3], wherein the copolymer has a crosslinked structure.

[0064] [5] The gas separation membrane according to any one of [1] to [4], further comprising a porous support layer, wherein the separation function layer is provided on the porous support layer.

[0065] [6] The gas separation membrane according to any one of [1] to [5], which is used to selectively allow carbon dioxide to permeate from a mixed gas containing carbon dioxide and nitrogen.

[0066] [7] A gas separation device comprising the gas separation membrane according to any one of [1] to [6].

[0067] [8] A gas separation membrane having a separation functional layer containing a copolymer, wherein the copolymer contains an ethylene oxide structure and a propylene oxide structure, and the copolymer is a random copolymer.

[0068] [9] The method for producing a gas separation membrane according to any one of [1] to [6], wherein a copolymer containing an ethylene oxide structure and a propylene oxide structure is used to produce a gas separation membrane containing a copolymer having a weight average molecular weight of 13,000 or more.

[0069] An embodiment of the present invention will now be described.

[0070] The present invention will be explained in more detail below by showing examples and comparative examples, but the present invention is not limited to these examples.

[0071] [Molecular Weight Measurement] The copolymer used in each Example or Comparative Example was dissolved in a solvent of water / acetonitrile (1 / 1) to which 50 mM lithium bromide was added. The resulting solution was subjected to GPC measurement under the following conditions to determine the molecular weight of the copolymer used in the Examples and Comparative Examples.

[0072] (Conditions for GPC measurement) Apparatus: Shimadzu LC-20A Column: 2 TSKgel α-M (mixed column, exclusion limit molecular weight: 10 million) Guard column: TSKgel guard column α Mobile phase: H ２ 0 / ATN = 1 / 1 with 50 mM LiBr added. *Acetonitrile (ATN) was high performance liquid chromatography (HPLC) grade, and lithium bromide (LiBr) was first-class reagent (anhydrous). Flow rate: 1 mL / min. Measurement time: 40 min. Column oven: 40°C. Detection: Refractive index detector (RID). Washing solvent: H ２ O / ATN=1 / 1 Dissolving solvent: H ２ 0 / ATN = 1 / 1 with 50 mM LiBr added. Sample concentration: 1 mg / mL. Injection volume: 10 μL. Molecular weight calibration: Agilent standard PEG / PEO (10 molecular weights ranging from 1,000 to 1,500,000). [Measurement of PPO ratio] The copolymer was dissolved in deuterated chloroform at a concentration of 1 wt%. NMR measurement of the resulting solution was performed under the following conditions. The PPO ratio was calculated using the following formula from the peak of the ether moiety (3.6 ppm) and the peak of the methyl group (1.1 ppm). PPO ratio = {(peak area of ​​methyl group) / 3} / {(peak area of ​​ether moiety) / 4 + (peak area of ​​methyl group) / 3} (NMR measurement conditions) Apparatus: AV600 Measurement: 1 H Total: 32 Temperature: Room temperature [Solvent fractionation] 100 ml of acetone was added to 3.0 g of PEO-PPO random copolymer (EP-1550H, manufactured by Meisei Chemical Industry Co., Ltd.) and the mixture was shaken. After standing, supernatant 1 was recovered. 100 ml of acetone was added to the precipitate remaining after collecting supernatant 1, and the mixture was shaken. After standing, supernatant 2 was recovered. 100 ml of acetone was added to the precipitate remaining after collecting supernatant 2, and the mixture was shaken. After standing, supernatant 3 was recovered. The solvent was distilled off from the precipitate remaining after collecting supernatant 3, to obtain copolymer B, which was the precipitate component in the acetone extraction. Supernatants 1 to 3 were mixed and the solvent was distilled off to obtain Copolymer A, which was the supernatant component (acetone-soluble component) in the acetone extraction.

[0073] [Surface Treatment of Porous Support Layer] A polypropylene (PP) porous membrane (Celgard (registered trademark) 2500, manufactured by Polypore Corporation) was prepared as a first porous support layer. Corona treatment was performed on one side of the first porous support layer using a corona surface modification evaluation device (TEC-4AX, manufactured by Kasuga Electric Works, treatment electrode width: 21 cm) under conditions of a discharge output of 75 W and a treatment speed of 1 m / min.

[0074] [Electron Beam Irradiation Treatment] The coating film was subjected to electron beam irradiation treatment using an electron beam irradiation device (EC250, manufactured by Iwasaki Electric Co., Ltd.) under the conditions of an irradiation dose of 50 kGy, a current of 5.6 mA, a voltage of 225 kV, a speed of 8 m / min, and a number of times once.

[0075] [UV Irradiation Treatment] The coated film was placed in a box and the atmosphere was replaced with nitrogen for 5 minutes. Using a UV irradiation device (manufactured by Eye Graphics Co., Ltd., ESC-601), the film was irradiated with light at a wavelength of 365 nm and an irradiation intensity of 188 mW / cm. ２ , cumulative light intensity 340 mJ / cm ２ The coating film was subjected to UV irradiation treatment once.

[0076] [Evaluation of Permeation Performance] The separation performance of the gas separation membranes obtained in each Example and Comparative Example was evaluated using a gas separation apparatus 100 equipped with a gas separation membrane cell 61 shown in Figure 3. Specifically, the prepared gas separation membrane was cut to an appropriate size to form a flat membrane shape, and the gas separation membrane 10 was fixed between the feed side chamber 62 and the permeation side chamber 63 of the stainless steel gas separation membrane cell 61. The temperature of the gas separation membrane cell was maintained at 40°C. ２ Gas or N ２ The gas was supplied to the feed-side chamber 62 of the gas separation membrane cell 61 at a flow rate of 60 NL / h or less. The pressure in the feed-side chamber 62 was adjusted to 100 kPaG (gauge pressure) by a back pressure regulator 65 installed in the middle of the discharge path for the non-permeated gas. The pressure in the permeation-side chamber 63 was atmospheric pressure, and the flow rate of the gas permeated through the gas separation membrane 10 was measured using a flow meter 67 installed downstream of the permeation chamber 63.

[0077] The flow rate of the gas that permeated the gas separation membrane 10 was measured when the gas separation apparatus 100 reached a steady state after starting operation. ２ Gas and N ２Each was performed using CO ２ Permeation flow rate and N ２ The permeation flow rate of the obtained CO ２ The permeation flow rate is N ２ Divide by the permeation flow rate of CO ２ / N ２ The selectivity was calculated.

[0078] Example 1 Preparation of Coating Liquid (A1) 0.9 g of PEO-PPO random copolymer (ALKOX EP1550H, manufactured by Meisei Chemical Industry Co., Ltd.), 21.7 g of water, and 0.01 g of a 10 wt % aqueous solution of surfactant (SURFLON S-242, manufactured by AGC Seimi Chemical Co., Ltd.) were mixed and stirred to obtain a composition. The obtained composition was filtered through a filter with a pore size of 2 μm to obtain Coating Liquid (A1).

[0079] (Preparation of gas separation membrane) The coating solution (A1) was applied to the corona-treated surface of the first porous support layer using a tabletop applicator set to a coating thickness of 25 μm to form a coating membrane. Thereafter, the coating membrane was dried at 25° C. for 12 hours to obtain a gas separation membrane.

[0080] [Example 2] (Preparation of gas separation membrane) The coating solution (A1) was applied to the corona-treated surface of the first porous support layer using a tabletop applicator set to a coating thickness of 100 μm to form a coating membrane. The coating membrane was subjected to electron beam irradiation treatment and then dried at 25° C. for 12 hours to obtain a gas separation membrane.

[0081] Example 3 Preparation of Coating Liquid (A3) 1.7 g of Copolymer B, 39.4 g of water, and 0.23 g of a 10 wt % aqueous solution of surfactant (Surflon S-242, manufactured by AGC Seimi Chemical Co., Ltd.) were mixed and stirred to obtain a composition. The obtained composition was filtered through a filter with a pore size of 2 μm to obtain Coating Liquid (A3).

[0082] (Preparation of gas separation membrane) The coating solution (A3) was applied to the corona-treated surface of the first porous support layer using a tabletop applicator set to a coating thickness of 100 μm to form a coating membrane. The formed coating membrane was then dried at 25° C. for 12 hours to obtain a gas separation membrane.

[0083] [Example 4] (Preparation of gas separation membrane) The coating solution (A3) was applied to the corona-treated surface of the first porous support layer using a tabletop applicator set to a coating thickness of 25 μm to form a coating membrane. The formed coating membrane was subjected to electron beam irradiation treatment and then dried at 25° C. for 12 hours to obtain a gas separation membrane.

[0084] Example 5 Preparation of Coating Liquid (A5) 1.7 g of Copolymer A, 39.4 g of water, and 0.23 g of a 10 wt % aqueous solution of surfactant (Surflon S-242, manufactured by AGC Seimi Chemical Co., Ltd.) were mixed and stirred to obtain a composition. The obtained composition was filtered through a filter with a pore size of 2 μm to obtain Coating Liquid (A5).

[0085] (Preparation of gas separation membrane) The coating solution (A5) was applied to the corona-treated surface of the first porous support layer using a tabletop applicator set to a coating thickness of 100 μm to form a coating membrane. The formed coating membrane was subjected to electron beam irradiation treatment and then dried at 25° C. for 12 hours to obtain a gas separation membrane.

[0086] Example 6 Preparation of Coating Solution (A6) 0.48 g of PEO-PPO random copolymer (ALKOX EP1010N, manufactured by Meisei Chemical Industry Co., Ltd.), 11.5 g of water, and 0.07 g of a 10 wt % aqueous solution of surfactant (SURFLON S-242, manufactured by AGC Seimi Chemical Co., Ltd.) were mixed and stirred to obtain a composition. The obtained composition was filtered through a filter with a pore size of 2 μm to obtain Coating Solution (A6).

[0087] (Preparation of gas separation membrane) The coating solution (A6) was applied to the corona-treated surface of the first porous support layer using a tabletop applicator set to a coating thickness of 25 μm to form a coating membrane. The coating membrane was subjected to electron beam irradiation treatment and then dried at 25° C. for 12 hours to obtain a gas separation membrane.

[0088] Example 7 Preparation of Coating Solution (A7) 0.48 g of PEO-PPO-PhGE random copolymer (Meisei Chemical Industry Co., Ltd., Alkox CP-B1, containing phenyl groups, PEO:PPO:PhGE molar ratio of 98:1:1), 11.5 g of water, and 0.07 g of a 10 wt % aqueous solution of surfactant (AGC Seimi Chemical, Surflon S-242) were mixed and stirred to obtain a composition. The obtained composition was filtered through a filter with a pore size of 2 μm to obtain coating solution (A7).

[0089] (Preparation of gas separation membrane) The coating solution (A7) was applied to the corona-treated surface of the first porous support layer using a tabletop applicator set to a coating thickness of 25 μm to form a coating membrane. The formed coating membrane was subjected to electron beam irradiation treatment and then dried at 25° C. for 12 hours to obtain a gas separation membrane.

[0090] Example 8 Preparation of Coating Solution (A8) 1.20 g of a PEO-PPO-AGE random copolymer (Meisei Chemical Industry Co., Ltd., ALKOX CP-A13H, allyl group-containing, PEO:PPO:AGE molar ratio of 93:5:2), 2.40 g of a 0.5 wt % aqueous solution of a photopolymerization initiator (Tokyo Chemical Industry Co., Ltd., Irgacure 2959), 26.2 g of water, and 0.165 g of a 10 wt % aqueous solution of a surfactant (AGC Seimi Chemical Co., Ltd., Surflon S-242) were mixed and stirred to obtain a composition. The resulting composition was then filtered through a filter with a pore size of 2 μm to obtain Coating Solution (A8).

[0091] (Preparation of gas separation membrane) The coating solution (A8) was applied to the corona-treated surface of the first porous support layer using a tabletop applicator set to a coating thickness of 100 μm to form a coating membrane. The formed coating membrane was then dried at 25° C. for 12 hours to obtain a gas separation membrane.

[0092] [Example 9] (Preparation of gas separation membrane) The coating solution (A8) was applied to the corona-treated surface of the first porous support layer using a tabletop applicator set to a coating thickness of 100 μm to form a coating membrane. The coating membrane was subjected to UV irradiation treatment and then dried at 25° C. for 12 hours to obtain a gas separation membrane.

[0093] Example 10 (Preparation of Coating Solution (A10)) 1.20 g of a PEO-PPO-AGE random copolymer (Meisei Chemical Industry Co., Ltd., ALKOX CP-A2H, containing allyl groups, PEO:PPO:AGE molar ratio of 96:1:3), 2.40 g of a 0.5 wt % initiator aqueous solution (Tokyo Chemical Industry Co., Ltd., Irgacure 2959), 26.2 g of water, and 0.165 g of a 10 wt % surfactant aqueous solution (AGC Seimi Chemical, Surflon S-242) were mixed and stirred to obtain a composition. The resulting composition was then filtered through a filter with a pore size of 2 μm to obtain Coating Solution (A10).

[0094] (Preparation of gas separation membrane) The coating solution (A10) was applied to the corona-treated surface of the first porous support layer using a tabletop applicator set to a coating thickness of 100 μm to form a coating membrane. The formed coating membrane was then dried at 25° C. for 12 hours to obtain a gas separation membrane.

[0095] [Example 11] (Preparation of gas separation membrane) The coating solution (A10) was applied to the corona-treated surface of the first porous support layer using a tabletop applicator set to a coating thickness of 100 μm to form a coating membrane. The formed coating membrane was subjected to UV irradiation treatment and then dried at 25° C. for 12 hours to obtain a gas separation membrane.

[0096] Comparative Example 1 Preparation of Coating Liquid (B1) 4.0 g of Pluronic (registered trademark) F-127 (P2443, manufactured by Merck) and 16.0 g of water were mixed and stirred to obtain a composition. The obtained composition was filtered through a filter with a pore size of 2 μm to obtain Coating Liquid (B1).

[0097] (Preparation of gas separation membrane) The coating solution (B1) was applied to the corona-treated surface of the first porous support layer using a tabletop applicator set to a coating thickness of 100 μm to form a coating membrane. The formed coating membrane was then dried at 25° C. for 12 hours to obtain a gas separation membrane.

[0098] Comparison between Examples and Comparative Examples shows that when the weight average molecular weight of the copolymer contained in the separation functional layer of the gas separation membrane is 13,000 or more and / or the copolymer is a random copolymer, the resulting gas separation membrane can exhibit sufficient CO ２ / N ２Furthermore, it was confirmed that the copolymer has selectivity for CO 2 because the ratio of propylene oxide structures (PPO ratio) contained in the copolymer is 17 mol % or less in 100 mol % of the main chain structural units of the copolymer. ２ / N ２ It was also confirmed that the selectivity was excellent.

[0099] Furthermore, when Examples 1 and 2, Examples 3 and 4, Examples 8 and 9, and Examples 10 and 11 are compared, it is clear that the crosslinked copolymers provide better CO ２ / N ２ It was confirmed that selectivity could be obtained.

[0100] One aspect of the present invention can be used in a gas separation membrane that separates a specific gas component from a mixed gas.

[0101] REFERENCE SIGNS LIST 10 Gas separation membrane 11 Porous support layer 12 Protective layer 13 Reinforcement layer 15 Separation function layer 61 Gas separation membrane cell 62 Feed side chamber 63 Permeation side chamber 65 Back pressure regulator 67 Flow meter 100 Gas separation device

Claims

1. A gas separation membrane having a separation functional layer containing a copolymer, wherein the copolymer contains an ethylene oxide structure and a propylene oxide structure, and the weight average molecular weight of the copolymer is 13,000 or more.

2. The gas separation membrane according to claim 1, wherein the copolymer is a random copolymer.

3. The gas separation membrane according to claim 1, wherein the proportion of the propylene oxide structure contained in the copolymer is 17 mol % or less based on 100 mol % of the structural units of the main chain of the copolymer.

4. The gas separation membrane according to claim 1, wherein the copolymer has a crosslinked structure.

5. The gas separation membrane according to claim 1, further comprising a porous support layer, wherein the separation function layer is provided on the porous support layer.

6. The gas separation membrane according to claim 1, which is used to selectively permeate carbon dioxide from a mixed gas containing carbon dioxide and nitrogen.

7. A gas separation device comprising the gas separation membrane according to any one of claims 1 to 6.

8. A gas separation membrane having a separation functional layer containing a copolymer, wherein the copolymer contains an ethylene oxide structure and a propylene oxide structure, and the copolymer is a random copolymer.

9. A method for producing a gas separation membrane according to any one of claims 1 to 6, in which a copolymer containing an ethylene oxide structure and a propylene oxide structure is used to produce a gas separation membrane containing a copolymer having a weight average molecular weight of 13,000 or more.

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