Separation membrane and method for manufacturing the same

Abstract

The present invention provides a separation membrane suited to suppressing variation in separation power. The separation membrane 10 according to the present invention comprises: a first separation function layer 1; a porous supporting body 3 which supports the separation function layer 1; and an intermediate layer 2 which is disposed between the separation function layer 1 and the porous supporting body 3 and is formed from an emulsion resin composition. The emulsion resin composition includes, for example, a silicone polymer, a hydrophilic polymer, etc.

Description

[Technical Field]

[0001] The present invention relates to a separation membrane and a method for producing the same. [Background technology]

[0002] Membrane separation is a method developed to separate acidic gases, such as carbon dioxide, from gas mixtures containing them. Compared to absorption methods, which separate acidic gases by having an absorbent absorb them, membrane separation can efficiently separate acidic gases while keeping operating costs down.

[0003] Examples of separation membranes used in membrane separation methods include composite membranes in which a separation functional layer is formed on a porous support. In the field of separation membranes, an intermediate layer is sometimes placed between the separation functional layer and the porous support in order to reduce the thickness of the separation functional layer (for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 6186286 [Patent Document 2] Japanese Patent Publication No. 2019-209274 [Overview of the project] [Problems that the invention aims to solve]

[0005] Conventional separation membranes require suppression of variations in separation performance depending on the measurement location.

[0006] Therefore, the present invention provides a separation membrane suitable for suppressing variations in separation performance. [Means for solving the problem]

[0007] The intermediate layer can be produced, for example, by applying a solution containing a material for the intermediate layer onto a porous support and drying the resulting coating film. However, studies conducted by the present inventors have revealed that when the above solution is applied onto a porous support, the solution tends to permeate into the interior of the porous support. When the solution permeates into the porous support, not only does variation in the thickness of the intermediate layer occur, but defects may also arise in the formed intermediate layer. The present inventors have newly found that when a separation functional layer is further formed on the intermediate layer formed by the above method, variation in separation performance of the separation membrane occurs, and have thus completed the present invention.

[0008] The present invention provides a separation functional layer, a porous support that supports the separation functional layer, and an intermediate layer disposed between the separation functional layer and the porous support and formed from an emulsion resin composition, a separation membrane comprising

[0009] Further, the present invention provides a method for producing a separation membrane comprising a separation functional layer, a porous support that supports the separation functional layer, and an intermediate layer disposed between the separation functional layer and the porous support, the production method comprising: applying an emulsion resin composition onto the porous support to form a coating film; and drying the coating film to form the intermediate layer, a method for producing a separation membrane comprising

[0010] Further, the present invention provides a separation functional layer, a porous support that supports the separation functional layer, and an intermediate layer disposed between the separation functional layer and the porous support and containing a silicone-based polymer and a hydrophilic polymer, a separation membrane comprising Effects of the Invention

[0011] According to the present invention, a separation membrane suitable for suppressing variation in separation performance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a separation membrane according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of a membrane separation apparatus provided with the separation membrane of the present invention. [Figure 3] FIG. 3 is a perspective view schematically showing a modified example of a membrane separation apparatus provided with the separation membrane of the present invention. [Figure 4A] FIG. 4 is an electron microscope image of the surface of an intermediate layer at a stage before forming a separation functional layer in the separation membrane of Comparative Example 1. [Figure 4B] FIG. 5 is an image showing a state after a staining solution is applied onto the separation functional layer of the separation membrane of Comparative Example 1. MODES FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, the present invention will be described in detail, but the following description is not intended to limit the present invention to a specific embodiment.

[0014] <Embodiment of Separation Membrane> As shown in FIG. 1, the separation membrane 10 of the present embodiment includes a separation functional layer 1, an intermediate layer 2, and a porous support 3. The intermediate layer 2 is disposed between the separation functional layer 1 and the porous support 3, and is in direct contact with each of the separation functional layer 1 and the porous support 3. The intermediate layer is formed from an emulsion resin composition.

[0015] (Separation Functional Layer) The separation functional layer 1 is, for example, a layer that can preferentially permeate acidic gases contained in a gas mixture. In a preferred embodiment, the separation functional layer 1 includes a resin. Examples of resins included in the separation functional layer 1 include polyether block amide resins, polyamide resins, polyether resins, polyimide resins, cellulose acetate resins, silicone resins, and fluororesins. The separation functional layer 1 preferably includes a polyether block amide resin. In this embodiment, the separation functional layer 1 preferably consists substantially of a resin. In this specification, "substantially consisting of" means excluding other components that alter the essential characteristics of the material mentioned, for example, that 95 wt% or more, and more precisely 99 wt% or more, is composed of the material. However, the separation functional layer 1 may further contain additives other than the resin, such as leveling agents.

[0016] In another preferred embodiment, the separation functional layer 1 comprises an ionic liquid. The separation functional layer 1 comprises, for example, a double network gel comprising an ionic liquid. The double network gel is a gel comprising two independent network structures. The double network gel comprises, for example, a first network structure composed mainly of organic material, a second network structure composed mainly of inorganic material, and an ionic liquid. In this specification, "composed mainly of" means that 50 wt% or more, and more specifically 70 wt% or more, of the material is composed of the said material.

[0017] The organic material for constituting the first network structure includes, for example, polymers such as polyacrylamide (particularly polydialkylacrylamide such as polydimethylacrylamide). The polymer contained in the organic material has structural units derived from acrylamide derivatives and may further contain crosslinked structures. Polymers containing crosslinked structures can be prepared by known methods. For example, first, a prepolymer having structural units having N-hydroxysuccinimide ester groups is prepared. Structural units having N-hydroxysuccinimide ester groups are derived, for example, from N-acrylooxysuccinimide. Next, a polymer containing crosslinked structures can be obtained by reacting the prepolymer with an amine-based crosslinking agent. The amine-based crosslinking agent is a compound having two or more primary amino groups, for example, ethylene glycol bis(3-aminopropyl) ether.

[0018] The second network structure may include a network of multiple particles. This network of particles is formed, for example, by multiple particles being bonded to each other by hydrogen bonds. The particles included in the second network structure may include inorganic materials or organic materials. Examples of inorganic materials included in these particles include silica, titania, and alumina. As an example, the particles included in the second network structure are silica particles.

[0019] In this embodiment, examples of ionic liquids include ionic liquids having imidazolium, pyridinium, ammonium, or phosphonium and a substituent having one or more carbon atoms.

[0020] In an ionic liquid having imidazolium and a substituent having 1 or more carbon atoms, examples of substituents having 1 or more carbon atoms include alkyl groups having 1 to 20 carbon atoms, cycloalkyl groups having 3 to 14 carbon atoms, and aryl groups having 6 to 20 carbon atoms. These may be further substituted with hydroxyl groups, cyano groups, amino groups, monovalent ether groups, etc. (for example, hydroxyalkyl groups having 1 to 20 carbon atoms).

[0021] Examples of alkyl groups having 1 to 20 carbon atoms include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-eicosadecyl. Examples include hydroxyl groups, i-propyl groups, sec-butyl groups, i-butyl groups, 1-methylbutyl groups, 1-ethylpropyl groups, 2-methylbutyl groups, i-pentyl groups, neopentyl groups, 1,2-dimethylpropyl groups, 1,1-dimethylpropyl groups, t-pentyl groups, 2-ethylhexyl groups, and 1,5-dimethylhexyl groups, which may be further substituted with hydroxyl groups, cyano groups, amino groups, monovalent ether groups, etc.

[0022] The alkyl groups described above may be substituted with cycloalkyl groups. The number of carbon atoms in the alkyl groups substituted with cycloalkyl groups is, for example, 1 to 20. Examples of alkyl groups substituted with cycloalkyl groups include cyclopropylmethyl group, cyclobutylmethyl group, cyclohexylmethyl group, and cyclohexylpropyl group, which may be further substituted with hydroxyl groups, cyano groups, amino groups, monovalent ether groups, etc.

[0023] Examples of cycloalkyl groups having 3 to 14 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclododecyl, norbornyl, bornyl, and adamantyl groups, which may be further substituted with hydroxyl, cyano, amino, or monovalent ether groups.

[0024] Examples of aryl groups having 6 to 20 carbon atoms include phenyl, toluyl, xylyl, mesityl, anisyl, naphthyl, and benzyl groups, which may be further substituted with hydroxyl, cyano, amino, or monovalent ether groups.

[0025] Compounds having imidazolium and substituents with one or more carbon atoms may further have substituents such as alkyl groups and may form salts with counter anions. Examples of counter anions include alkyl sulfates, tosylates, methanesulfonates, acetates, bis(fluorosulfonyl)imides, bis(trifluoromethanesulfonyl)imides, thiocyanates, dicyanamides, tricyanomethanides, tetracyanoborates, hexafluorophosphates, tetrafluoroborates, and halides. From the viewpoint of gas separation performance, bis(fluorosulfonyl)imides, bis(trifluoromethanesulfonyl)imides, dicyanamides, tricyanomethanides, and tetracyanoborates are preferred.

[0026] Ionic liquids having imidazolium and substituents with one or more carbon atoms include, specifically, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-ethyl-3-methylimidazolium dicyanamide, 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoromethanephosphate, 1-butyl-3-methylimidazolium tetrachloroferate, 1-butyl-3-methylimidazolium iodide, 1-butyl-2,3-dimethylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium hexafluorophosphate, and 1-butyl-2,3-dimethylimidazolium tetrafluorophosphate. Lafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium trifluoro(trifluoromethyl)borate, 1-butyl-3-methylimidazolium tribromide, 1,3-dimesitylyimidazolium chloride, 1,3-bis(2,6-diisopropylphenyl)imidazolium chloride, 1,3-diisopropylimidazolium tetrafluoroborate, 1,3-di-tert-butylimidazolium tetrafluoroborate, 1,3-dicyclohexylimidazolium tetrafluoroborate, 1,3-dicyclohexylimidazolium chloride, 1,2-dimethyl-3-propylimidazolium iodide, 1-hexyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium bromide, 1-methyl-3-propylimidazolium iodide, 1-methyl-3-n-octylimidazolium bromide, 1 Examples include methyl-3-n-octylimidazolium chloride, 1-methyl-3-n-octylimidazolium hexafluorophosphate, 1-methyl-3-[6-(methylsulfinyl)hexyl]imidazolium p-toluenesulfonate, 1-ethyl-3-methylimidazolium tricyanomethanide, and 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0027] In particular, from the viewpoint of gas separation performance, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([EMI][FSI]), 1-ethyl-3-methylimidazolium dicyanamide ([EMI][DCA]), 1-ethyl-3-methylimidazolium tricyanomethanide ([EMI][TCM]), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][TF2N]), and 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C2OHim][TF2N]) are especially preferred.

[0028] The method for preparing the double network gel is not particularly limited, and for example, the method disclosed in E. Kamio et al., Adv. Mater, 29, 1704118 (2017) can be used.

[0029] The ionic liquid content in the double network gel is, for example, 50 wt% or more, preferably 60 wt% or more, more preferably 70 wt% or more, and even more preferably 80 wt% or more. The higher the ionic liquid content, the more preferentially the separation functional layer 1 can permeate the acidic gas contained in the mixed gas. The upper limit of the ionic liquid content is not particularly limited, and is, for example, 95 wt%.

[0030] The content of the first network structure, which is mainly composed of organic material, in the double network gel is, for example, 1 wt% or more, preferably 5 wt% or more, and more preferably 10 wt% or more. The upper limit of the content of the first network structure is, for example, 15 wt%. The content of the second network structure, which is mainly composed of inorganic material, in the double network gel is, for example, 1 wt% or more, from the viewpoint of improving the strength of the double network gel. The upper limit of the content of the second network structure is, for example, 5 wt%. The ratio of the total weight of the first network structure and the second network structure to the weight of the double network gel is, for example, 2 wt% or more, preferably 5 wt% or more, and more preferably 10 wt% or more. This ratio is preferably 20 wt% or less. In this embodiment, the separation functional layer 1 preferably consists substantially of a double network gel.

[0031] The thickness of the separation functional layer 1 is, for example, 50 μm or less, preferably 25 μm or less, and more preferably 15 μm or less. The thickness of the separation functional layer 1 may, in some cases, be 10 μm or less, 5.0 μm or less, or 2.0 μm or less. The thickness of the separation functional layer 1 may be 0.05 μm or more, or 0.1 μm or more.

[0032] (Middle class) As described above, in this embodiment, the intermediate layer 2 is formed from an emulsion resin composition. The emulsion resin composition means a liquid containing a dispersion medium and a polymer emulsified in the dispersion medium. The emulsion resin composition preferably contains water as the dispersion medium. That is, the emulsion resin composition is preferably an oil-in-water (O / W) emulsion. The emulsion resin composition may contain an organic solvent as the dispersion medium, either in place of water or together with water. Examples of organic solvents included in the emulsion resin composition include 2-ethylhexanol, butyl cellulose, dipropylene glycol, ethylene glycol, propylene glycol, n-propyl alcohol, and isopropanol, and from the viewpoint of polymer dispersibility in the emulsion resin composition, ethylene glycol and propylene glycol are preferred.

[0033] The emulsion resin composition includes, for example, a silicone-based polymer. The silicone-based polymer has, for example, a constituent unit A represented by the following formula (1). [ka]

[0034] In equation (1), R 1 and R 2 These are, independently of each other, a hydrogen atom or a hydrocarbon group. The hydrocarbon group may be linear or branched. The number of carbon atoms in the hydrocarbon group is not particularly limited, for example, 1 to 5, preferably 1 to 4, and more preferably 1 to 3. The hydrocarbon group is preferably a linear or branched alkyl group. Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl groups. The hydrocarbon group may also be an unsaturated hydrocarbon group such as a vinyl group. 1 and R 2 It is preferable that this is a hydrogen atom, a methyl group, an ethyl group, or a vinyl group.

[0035] The number of constituent units A contained in the silicone polymer is not particularly limited, and is, for example, 100 to 100,000, preferably 200 to 90,000, and more preferably 500 to 80,000.

[0036] A silicone polymer, for example, contains constituent unit A as its main component, and preferably consists substantially of constituent unit A alone. In this specification, “main component” means the constituent unit that is present in the largest amount by weight among all constituent units of the silicone polymer. However, the silicone polymer may further contain other constituent units other than constituent unit A.

[0037] Dimethylpolysiloxane is a specific example of a silicone-based polymer. The silicone-based polymer may also be a cyclic siloxane represented by the following formula (2). [ka]

[0038] In equation (2), R 1 and R 2 This is the same as equation (1). n is not particularly limited, for example, 100 to 100,000, preferably 200 to 90,000, and more preferably 500 to 80,000.

[0039] The weight-average molecular weight of silicone polymers is not particularly limited, for example, 1 × 10⁻⁶ 4 ~1 × 10 6 That is the case.

[0040] In the emulsion resin composition, the silicone polymer is dispersed, for example, in the form of particles. The average particle size of the silicone polymer is not particularly limited, but is, for example, 10 to 1000 nm, and preferably 50 to 800 nm. In this specification, the average particle size means the median diameter determined from the particle size distribution measured by a particle size distribution analyzer based on the laser diffraction-scattering method. In particular, the average particle size of the silicone polymer can be measured using a laser diffraction-scattering particle size distribution analyzer (for example, LS 13 320 from Beckman Coulter) in accordance with the provisions of ISO 13320:2009 "Particle size analysis - Laser diffraction method -".

[0041] The method for preparing the emulsion resin composition containing the silicone polymer is not particularly limited, and known methods disclosed in Japanese Patent Application Publication No. 2004-339283 and others can be used as appropriate.

[0042] The emulsion resin composition may further contain surfactants for dispersing the silicone polymer. Examples of surfactants include anionic surfactants such as alkyl sulfates, alkylbenzene sulfonates, and alkyl phosphates; nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene fatty acid esters; cationic surfactants such as quaternary ammonium salts and alkylamine acetates; and amphoteric surfactants such as alkyl betaines and alkylimidazolines. In particular, from the viewpoint of dispersion stability of the silicone polymer, it is preferable to use nonionic surfactants such as polyoxyethylene alkyl ethers and polyoxyethylene alkylphenyl ethers. Specific examples of these nonionic surfactants include polyoxyethylene octyl ether, polyoxyethylene nonyl ether, polyoxyethylene decyl ether, polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, and polyoxyethylene styrene-phenyl ether. Surfactants can be used individually or in combination of two or more.

[0043] The emulsion resin composition may contain a hydrophilic polymer in place of, or together with, a silicone polymer. In this specification, "hydrophilic polymer" means a polymer having a contact angle with water of 100° or less, preferably 90° or less, and more preferably 85.2° or less. The contact angle with water can be evaluated using a sheet made of the polymer to be evaluated by the static drop method specified in Japanese Industrial Standard (JIS) R3257:1999. The lower limit of the contact angle with water of the hydrophilic polymer is not particularly limited, but may be, for example, 30°, 50°, or 74.0°.

[0044] The hydrophilic polymer includes, for example, at least one selected from the group consisting of urethane polymers, (meth)acrylic polymers, (meth)acrylic urethane polymers, ester polymers, and vinyl ester polymers, and preferably includes a urethane polymer.

[0045] Examples of urethane polymers include polyurethanes obtained by the reaction of polyols and polyisocyanates, and modified products thereof. The urethane polymer may also be a urethane prepolymer having isocyanate groups or blocked isocyanate groups at its terminals.

[0046] Examples of polyols include polyethylene glycol, polypropylene glycol, polyoxytetramethylene ether glycol, and other polyether polyols obtained by ring-opening polymerization of ethylene oxide, propylene oxide, tetrahydrofuran, etc.; ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, octanediol, 1,4-butynediol, dipropylene glycol, bisphenol A, and bisphenol A with propylene oxide. Examples include saturated or unsaturated low molecular weight glycols such as additives, bisphenol A ethylene oxide adducts, and hydrogenated bisphenol A; polyester polyols obtained by dehydrating and condensing these low molecular weight glycols with dibasic acids such as adipic acid, maleic acid, fumaric acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, azelaic acid, sebacic acid, and suberic acid, or their corresponding acid anhydrides; polyester polyols obtained by ring-opening polymerization of lactones such as ε-caprolactone and β-methyl-δ-valerolactone; and high molecular weight polyols commonly used in the production of polyurethanes, such as polycarbonate polyols and polybutadiene glycols. In addition, various polyols such as glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, pentaerythritol, and sorbitol can be used instead of the low molecular weight glycols mentioned above. From the viewpoint of dispersibility in emulsion resin compositions, polyols having hydrophilic parts such as ethylene oxide adducts are preferred.

[0047] As the polyisocyanate, aromatic, aliphatic, or alicyclic diisocyanates can be used. Examples of diisocyanates include 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyli isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylenediisocyanate, 1,4-phenylenediisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropyl diisocyanate, and methylene diisocyanate. Examples include 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanate-methyl)cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate, and dimer isocyanates obtained by converting the carboxyl group of a dimer acid to an isocyanate group.

[0048] Examples of isocyanate group blocking agents include bisulfites, phenols containing sulfonic acid groups, alcohols, lactam oximes, and active methylene compounds.

[0049] To improve dispersibility in the emulsion resin composition, hydrophilic groups such as carboxylates may be introduced into the urethane polymer.

[0050] (Meth)acrylic polymers, for example, have constituent units derived from alkyl (meth)acrylates as their main component. In this specification, "(meth)acrylate" means acrylate and / or methacrylate.

[0051] The alkyl group contained in alkyl(meth)acrylate is not particularly limited and may be, for example, a linear, branched, or cyclic alkyl group having 2 to 14 carbon atoms.

[0052] Examples of alkyl (meth)acrylates include alkyl acrylates having an alkyl group with 2 to 14 carbon atoms, preferably alkyl acrylates having an alkyl group with 4 to 9 carbon atoms. Examples of alkyl acrylates include n-butyl acrylate, isobutyl acrylate, s-butyl acrylate, isoamyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, nonyl acrylate, and isononyl acrylate.

[0053] The alkyl (meth)acrylate may be, for example, an alkyl methacrylate ester having an alkyl group with 2 to 14 carbon atoms, preferably an alkyl methacrylate ester having an alkyl group with 2 to 10 carbon atoms. Examples of alkyl methacrylate esters include ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, bornyl methacrylate, and isobornyl methacrylate.

[0054] Alkyl (meth)acrylates can be used individually or in combination of two or more of the above-mentioned types. The content of constituent units derived from alkyl (meth)acrylate in the (meth)acrylic polymer is not particularly limited, but is, for example, 70 to 100 wt%, preferably 85 to 99 wt%, and more preferably 87 to 99 wt%.

[0055] The (meth)acrylic polymer may further contain constituent units derived from copolymer monomers copolymerizable with alkyl (meth)acrylates. Examples of copolymer monomers include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; alkyl (meth)acrylates having alkyl groups with 1 or more carbon atoms; aryl (meth)acrylates such as phenyl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; styrene monomers such as styrene; epoxy group-containing monomers such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate; hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-butyl (meth)acrylamide, N-methylol (meth)acrylamide, and N-methylolpropane (meth)acrylamide. Nitrogen atom-containing monomers such as amides, (meth)acryloylmorpholine, (meth)aminoethyl acrylate, N,N-dimethylaminoethyl meth)acrylate, and t-butylaminoethyl meth)acrylate; alkoxy group-containing monomers such as methoxyethyl meth)acrylate and ethoxyethyl meth)acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; functional monomers such as 2-methacryloyloxyethyl isocyanate; olefin monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; vinyl ether monomers such as vinyl ether; halogen atom-containing monomers such as vinyl chloride; vinyl group-containing heterocyclic compounds such as N-vinylpyrrolidone, N-(1-methylvinyl)pyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, and N-vinylmorpholine; N-vinyl carboxylic acid amides;Maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; itaconimide monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, and N-laurylitaconimide; N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide Succinimide monomers such as mido, N-(meth)acryloyl-8-oxyoctamethylenesuccinimide; sulfonic acid group-containing monomers such as styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid; phosphate group-containing monomers; polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methacrylate Glycol-based acrylic ester monomers such as xyethylene glycol and methoxypolypropylene glycol (meth)acrylate; acrylic acid ester monomers containing heterocyclic or halogen atoms such as tetrahydrofurfuryl (meth)acrylate and fluorine (meth)acrylate; (mono or poly)alkylene glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetraethylene glycol di(meth)acrylate, and propylene glycol di(meth)acrylate; esters of (meth)acrylic acid with polyhydric alcohols such as neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol hexa(meth)acrylate; polyfunctional vinyl compounds such as divinylbenzene;Examples include compounds having reactive unsaturated double bonds, such as allyl (meth)acrylate and vinyl (meth)acrylate.

[0056] Examples of (meth)acrylic urethane polymers include reaction products of (meth)acrylic polyol and polyisocyanate. Examples of (meth)acrylic polyols include (meth)acrylic polymers containing constituent units derived from hydroxyl group-containing (meth)acrylate. Examples of hydroxyl group-containing (meth)acrylates include those described above for (meth)acrylic polymers. Examples of polyisocyanates include those described above for urethane polymers. The polyisocyanate may be a urethane prepolymer having isocyanate groups.

[0057] Examples of ester polymers include those obtained by polycondensation of dicarboxylic acids and diols. Examples of dicarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, 2-methylterephthalic acid, 5-sulfisophthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-diphenylketonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalene. Examples include aromatic dicarboxylic acids such as dicarboxylic acids; alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid; aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and dodecanoic acid; unsaturated dicarboxylic acids such as maleic acid, maleic anhydride, and fumaric acid; and derivatives thereof (e.g., lower alkyl esters of dicarboxylic acids). These can be used individually or in combination of two or more.

[0058] Examples of diols include aliphatic diols such as ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, and polyoxytetramethylene glycol; alicyclic diols such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, and 1,4-cyclohexanedimethylol; and aromatic diols such as xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis(4'-hydroxyphenyl)propane, and bis(4-hydroxyphenyl)sulfone. These may be used alone or in combination of two or more thereof.

[0059] The vinyl ester polymer has, for example, structural units derived from a vinyl ester. Examples of the vinyl ester include vinyl acetate, vinyl propionate and the like. The vinyl ester polymer may further have structural units derived from an olefin such as ethylene, propylene or the like. A specific example of the vinyl ester polymer is an ethylene-vinyl acetate copolymer.

[0060] The weight average molecular weight of the hydrophilic polymer is not particularly limited, and is, for example, 1×10 4 to 1×10 7 .

[0061] In the emulsion resin composition, the hydrophilic polymer is dispersed, for example, in the form of particles. The average particle diameter of the hydrophilic polymer is not particularly limited, and is, for example, 10 to 1000 nm, preferably 50 to 800 nm. The average particle diameter of the hydrophilic polymer can be measured by the method described above for the silicone-based polymer.

[0062] The emulsion resin composition containing a hydrophilic polymer can be produced, for example, by emulsion polymerization of a monomer component for forming the hydrophilic polymer in the presence of an emulsifier (surfactant).

[0063] The emulsion resin composition may further contain a surfactant for dispersing the hydrophilic polymer. Examples of surfactants include those mentioned above for silicone polymers.

[0064] The emulsion resin composition may further contain other surfactants different from the surfactants used to disperse the silicone-based polymer or hydrophilic polymer described above. Depending on the type of other surfactant, it may be possible to improve the wettability of the emulsion resin composition to the metal rolls of a coater, such as a gravure coater. Therefore, when the emulsion resin composition contains other surfactants, it tends to be possible to uniformly coat the emulsion resin composition using a coater equipped with metal rolls. By uniformly coating the emulsion resin composition, it tends to be possible to suppress variations in the thickness of the intermediate layer 2 formed from the emulsion resin composition.

[0065] Other surfactants include, for example, silicone-based surfactants. Silicone-based surfactants include, for example, modified polysiloxanes having hydrophilic groups. Examples of hydrophilic groups include hydroxyl groups, carboxylic acid groups, sulfonic acid groups, (meth)acrylic groups, ester groups, and ether groups. A specific example of a modified group in modified polysiloxane is -(CH2CH2O) n -R(n is an integer between 5 and 30, R is a hydrogen atom or an alkyl group with 1 to 6 carbon atoms), -(CH2CHOHCH2) n Examples include -H (where n is an integer from 5 to 30). Specific examples of modified polysiloxanes include polyether-modified polydimethylsiloxanes. Commercially available silicone-based surfactants include the "BYK" series from BIC Chemie Japan, the "Toray Silicone" series from Toray Dow Corning, the "TSF" series from Momentive Performance Materials, and the "KP" and "KF" series from Shin-Etsu Silicone.

[0066] One example of the "BYK" series manufactured by BYChemie Japan is BYK-349. BYK-349 tends to suppress the decrease in the permeation rate of carbon dioxide permeating through the intermediate layer 2. BYK-349 has high dispersibility in water and is suitable for emulsion resin compositions containing water as a dispersion medium.

[0067] The emulsion resin composition may further contain a crosslinking agent for crosslinking silicone polymers or hydrophilic polymers. For example, the emulsion resin composition may contain a water-insoluble crosslinking agent for crosslinking a (meth)acrylic polymer having structural units derived from carboxyl group-containing monomers. The water-insoluble crosslinking agent is, for example, a water-insoluble compound having two or more functional groups (e.g., two to six, preferably three to five) that can react with carboxyl groups. In this specification, water-insoluble means that the weight of the compound soluble in 100 parts by weight of water at 25°C is 5 parts by weight or less, preferably 3 parts by mass or less, and more preferably 2 parts by mass or less. The weight of the water-soluble compound can be measured by the following method. First, the compound is mixed with the same weight of water (25°C) and stirred with a stirrer at 300 rpm for 10 minutes. The resulting mixture is separated into an aqueous phase and an oil phase by centrifugation. Next, the aqueous phase is removed and dried at 120°C for 1 hour. The weight of non-volatile components in the aqueous phase (the weight of compounds soluble in 100 parts by weight of water) is calculated from the loss on drying.

[0068] The functional group that can react with the carboxyl group is not particularly limited, and examples include epoxy groups, isocyanate groups, and carbodiimide groups, with epoxy groups being preferred from the viewpoint of reactivity. In particular, glycidylamino groups are preferred from the viewpoint of low contamination because they are highly reactive and less likely to leave unreacted products after the crosslinking reaction. That is, as a water-insoluble crosslinking agent, epoxy-based crosslinking agents having epoxy groups are preferred, and in particular, crosslinking agents having glycidylamino groups (glycidylamino-based crosslinking agents) are preferred.

[0069] Examples of water-insoluble crosslinking agents include glycidylamino-based crosslinking agents such as 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (e.g., manufactured by Mitsubishi Gas Chemical Company, trade name "TETRAD-C" etc.) [2 parts by weight or less that can be dissolved in 100 parts by weight of water at 25°C] and 1,3-bis(N,N-diglycidylaminomethyl)benzene (e.g., manufactured by Mitsubishi Gas Chemical Company, trade name "TETRAD-X" etc.) [2 parts by weight or less that can be dissolved in 100 parts by weight of water at 25°C]; and other epoxy-based crosslinking agents such as Tris(2,3-epoxypropyl)isocyanurate (e.g., manufactured by Nissan Chemical Industries, Ltd., trade name "TEPIC-G" etc.) [2 parts by weight or less that can be dissolved in 100 parts by weight of water at 25°C]. Water-insoluble crosslinking agents can be used alone or in combination of two or more.

[0070] The emulsion resin composition may further contain a filler. When an intermediate layer 2 is formed from an emulsion resin composition containing a filler, the permeation rate of carbon dioxide through the intermediate layer 2 tends to improve. The filler may contain inorganic materials or organic materials. Examples of inorganic materials included in the filler include zeolite and silica. The filler is preferably hydrophilic and has high dispersibility in water.

[0071] The filler has, for example, the shape of particles. The average particle diameter of the filler is, for example, smaller than the thickness of the intermediate layer 2 formed from the emulsion resin composition. The average particle diameter of the filler is, for example, 150 nm or less, may be 100 nm or less, or 50 nm or less. The lower limit of the average particle diameter of the filler is not particularly limited, but is, for example, 1 nm. The average particle diameter of the filler can be measured for silicone polymers by the method described above.

[0072] The filler may have pores. The average pore size of the filler is not particularly limited, for example, 0.1 nm to 5 nm. The density of the filler is not particularly limited, for example, 0.5 to 5 g / cm³. 3 That is the case.

[0073] Specific examples of fillers include the "Zeoal" series from Nakamura Choko Co., Ltd. and the "AEROSIL" series from Nippon Aerosil Co., Ltd. Examples of Nakamura Choko's "Zeoal" series include Zeoal 4A 50nm and Zeoal ZSM-5. These fillers contain zeolite. Examples of Nippon Aerosil's "AEROSIL" series include AEROSILOX50. This filler contains silica. Zeoal 4A 50nm and AEROSILOX50 tend to have higher hydrophilicity and better dispersibility in water compared to Zeoal ZSM-5.

[0074] The solid content concentration in the emulsion resin composition is not particularly limited, and is, for example, 10 to 60 wt%. If the emulsion resin composition contains a surfactant, the ratio of the weight of the surfactant to the total weight of the solid content in the emulsion resin composition is not particularly limited, and is, for example, 15 wt% or less, may be 5 wt% or less, or 1 wt% or less. If the ratio of the weight of the surfactant is 15 wt% or less, for example, when the emulsion resin composition is applied to the porous support 3, it is possible to sufficiently suppress the penetration of the emulsion resin composition into the porous support 3.

[0075] Intermediate layer 2 can be prepared, for example, by removing the dispersion medium from the emulsion resin composition. Therefore, intermediate layer 2 contains components derived from the emulsion resin composition. As an example, intermediate layer 2 contains at least one selected from the group consisting of silicone polymers and hydrophilic polymers, and preferably contains both silicone polymers and hydrophilic polymers. The silicone polymer contained in intermediate layer 2 may be a crosslinked product of the silicone polymer contained in the emulsion resin composition. Similarly, the hydrophilic polymer contained in intermediate layer 2 may be a crosslinked product of the hydrophilic polymer contained in the emulsion resin composition.

[0076] From another aspect, the present invention Separation function layer 1, A porous support 3 that supports the separation functional layer 1, Displaced between the separation functional layer 1 and the porous support 3, the intermediate layer 2 contains a silicone polymer and a hydrophilic polymer, A separation membrane 10 is provided, which is equipped with the following features.

[0077] The content of the silicone polymer in the intermediate layer 2 is not particularly limited, and is, for example, 10 wt% or more, preferably 30 wt% or more, more preferably 50 wt% or more, even more preferably 70 wt% or more, particularly preferably 80 wt% or more, and may be 90 wt% or more, 95 wt% or more, or 99 wt% or more. The intermediate layer 2 may be substantially composed of a silicone polymer. The higher the content of the silicone polymer in the intermediate layer 2, the greater the permeation rate of the permeate fluid from the separation membrane 10 tends to be. However, the content of the silicone polymer in the intermediate layer 2 may be less than 10 wt%, or 5 wt% or less. The intermediate layer 2 may not contain a silicone polymer at all.

[0078] The content of the hydrophilic polymer in the intermediate layer 2 is not particularly limited, and is, for example, 1 wt% or more, preferably 5 wt% or more, and more preferably 10 wt% or more. The higher the content of the hydrophilic polymer in the intermediate layer 2, the better the adhesion between the separation functional layer 1 and the intermediate layer 2 tends to be. The upper limit of the content of the hydrophilic polymer in the intermediate layer 2 is not particularly limited, and is, for example, 90 wt%, preferably 70 wt%, more preferably 50 wt%, even more preferably 30 wt%, and particularly preferably 20 wt%. The content of the hydrophilic polymer in the intermediate layer 2 is preferably 10 wt% to 20 wt%. However, in some cases, the intermediate layer 2 may be substantially composed of a hydrophilic polymer, or it may not contain a hydrophilic polymer at all.

[0079] Intermediate layer 2 may further contain other components besides the silicone polymer and hydrophilic polymer. Examples of other components include surfactants and fillers derived from the emulsion resin composition. That is, intermediate layer 2 may contain surfactants and fillers. For example, if intermediate layer 2 contains fillers, the fillers are embedded in a matrix containing the silicone polymer or hydrophilic polymer, and are preferably dispersed in the matrix. In intermediate layer 2, the fillers may be partially aggregated.

[0080] The surfactant content in intermediate layer 2 is not particularly limited and may be, for example, 15 wt% or less, 5 wt% or less, or 1 wt% or less. The lower limit of the surfactant content is not particularly limited and may be, for example, 0.1 wt%. The filler content in intermediate layer 2 is not particularly limited and may be, for example, 60 wt% or less, 40 wt% or less, 20 wt% or less, or 10 wt% or less. The lower limit of the filler content is not particularly limited and may be, for example, 1 wt%.

[0081] The thickness of the intermediate layer 2 is not particularly limited, and is, for example, less than 50 μm, preferably 40 μm or less, more preferably 30 μm or less, even more preferably 10 μm or less, and particularly preferably 5 μm or less. The smaller the thickness of the intermediate layer 2, the more likely it is that the decrease in the permeation rate of the permeating fluid from the separation membrane 10 can be suppressed. The lower limit of the thickness of the intermediate layer 2 is not particularly limited, and is, for example, 0.1 μm.

[0082] (porous support) The porous support 3 supports the separation functional layer 1 via the intermediate layer 2. Examples of the porous support 3 include nonwoven fabric; porous polytetrafluoroethylene; aromatic polyamide fiber; porous metal; sintered metal; porous ceramic; porous polyester; porous nylon; activated carbon fiber; latex; silicone; silicone rubber; permeable (porous) polymer containing at least one selected from the group consisting of polyvinyl fluoride, polyvinylidene fluoride, polyurethane, polypropylene, polyethylene, polycarbonate, polysulfone, polyetheretherketone, polyacrylonitrile, polyimide, and polyphenylene oxide; metal foam having open or closed cells; polymer foam having open or closed cells; silica; porous glass; mesh screen, etc. The porous support 3 may be a combination of two or more of these. The porous support 3 preferably contains polyvinylidene fluoride (PVDF).

[0083] The porous support 3 has an average pore diameter of, for example, 0.01 to 0.4 μm. The thickness of the porous support 3 is not particularly limited, but is, for example, 10 μm or more, preferably 20 μm or more, and more preferably 50 μm or more. The thickness of the porous support 3 is, for example, 300 μm or less, preferably 200 μm or less, and more preferably 150 μm or less.

[0084] (Method for preparing separation membranes) The method for manufacturing the separation membrane 10 of this embodiment includes, for example, applying an emulsion resin composition onto a porous support 3 to form a coating film, and drying the coating film to form an intermediate layer 2. The method for preparing the emulsion resin composition is not particularly limited. For example, the emulsion resin composition may be prepared by adding a surfactant, a filler, etc., to an emulsion containing a silicone polymer and / or a hydrophilic polymer. A slurry containing a filler and a dispersion medium (e.g., water) may be added to the emulsion. When a slurry containing a filler is added to the emulsion, the aggregation of the filler tends to be suppressed in the resulting emulsion resin composition. With an emulsion resin composition in which the aggregation of fillers is suppressed, the occurrence of defects can be suppressed when producing the intermediate layer 2. By adding a slurry containing a filler to the emulsion, the filler content in the intermediate layer 2 can also be easily increased.

[0085] The surface of the porous support 3 to which the emulsion resin composition is applied preferably has a relatively large contact angle with water. A surface of the porous support 3 with a large contact angle with water is suitable for preventing the emulsion resin composition, which contains water as a dispersion medium, from seeping into the interior of the porous support 3. The contact angle of the surface of the porous support 3 with respect to water is, for example, 60° or more, and preferably 70° or more. The upper limit of this contact angle is not particularly limited, and is, for example, 120°. The contact angle can be evaluated by the static droplet method specified in JIS R3257:1999.

[0086] The method for applying the emulsion resin composition is not particularly limited, and for example, spin coating, dip coating, etc., can be used. The emulsion resin composition may also be applied using a wire bar or the like. The method for applying the emulsion resin composition may also be a method using a metal roll, for example, gravure coating. Drying of the coated film can be carried out, for example, under heating conditions. The heating temperature of the coated film is, for example, 50°C or higher. The heating time of the coated film is, for example, 1 minute or more, and may be 5 minutes or more. The thickness of the intermediate layer 2 can be adjusted, for example, by the solid content concentration in the emulsion resin composition and the thickness of the coated film.

[0087] The surface of the intermediate layer 2 can be treated to facilitate adhesion as needed. Examples of such treatments include surface treatments such as application of a primer, corona discharge treatment, and plasma treatment.

[0088] Next, a coating solution containing the material for the separation functional layer 1 is prepared. The coating solution containing the material for the separation functional layer 1 is applied onto the intermediate layer 2 to obtain a coating film. By drying this coating film, the separation functional layer 1 can be formed. It is preferable that the surface of the intermediate layer 2 to which the coating solution is applied has a relatively small contact angle with water. A surface of the intermediate layer 2 with a small contact angle with water is suitable for improving adhesion with the separation functional layer 1. The contact angle of the surface of the intermediate layer 2 with respect to water is, for example, 120° or less, and preferably 110° or less. The lower limit of this contact angle is not particularly limited, and is, for example, 70°. The contact angle can be evaluated by the static droplet method specified in JIS R3257:1999.

[0089] Furthermore, the intermediate layer 2 having a surface with a small contact angle with water tends to have excellent adhesion to the porous support 3. As an example, the peeling force P1 of the intermediate layer 2 to the porous support 3 is, for example, 0.1 N / 18 mm or more, preferably 0.2 N / 18 mm or more, more preferably 0.3 N / 18 mm or more, even more preferably 0.4 N / 18 mm or more, and particularly preferably 0.5 N / 18 mm or more. The larger the peeling force P1, the greater the peeling force of the separation functional layer 1 to the intermediate layer 2 tends to be. The upper limit of the peeling force P1 is not particularly limited, and is, for example, 2.0 N / 18 mm.

[0090] The peel force P1 can be measured by the following method. First, the laminate of the intermediate layer 2 and the porous support 3 to be evaluated is cut to a size of 25 mm wide x 100 mm long to prepare a test specimen. Next, a single-sided adhesive tape (No. 7235, manufactured by Nitto Denko, Inc., 18 mm wide) is attached to the intermediate layer 2 on the test specimen, and a 2 kg roller is passed back and forth once to compress them. Next, using a commercially available tensile testing machine, the intermediate layer 2 is peeled off from the porous support 3 together with the single-sided adhesive tape at a peel angle of 90° and a peel speed of 300 mm / min. The peel force at this time is identified as the peel force P1. The above measurement is performed in an atmosphere of 23°C.

[0091] The coating method and drying conditions for the coating solution can be the same as those described above for the intermediate layer 2. The coating solution containing the material for the separation functional layer 1 may also be applied by spin coating. A separation membrane 10 is obtained by forming the separation functional layer 1 on the intermediate layer 2.

[0092] (Characteristics of the separation membrane) As described above, in the separation membrane 10 of this embodiment, the intermediate layer 2 is formed from an emulsion resin composition. According to the inventors' studies, even when an emulsion resin composition is applied to a porous support 3, the polymer contained in the emulsion resin composition does not easily penetrate into the interior of the porous support 3. In particular, when the emulsion resin composition contains water as a dispersion medium and the contact angle between the surface of the porous support 3 and water is large, the penetration of the polymer into the interior of the porous support 3 is significantly suppressed. Because the penetration of the polymer into the interior of the porous support 3 is suppressed, the formation of the intermediate layer 2 suppresses variations in thickness and the occurrence of defects such as pinholes. For example, with an emulsion resin composition, it is possible to easily produce an intermediate layer 2 with a relatively small thickness while suppressing variations in thickness. In this embodiment, the formation of the separation function layer 1 on the intermediate layer 2 formed from the emulsion resin composition tends to suppress variations in the separation performance of the separation membrane 10.

[0093] The separation membrane 10 can, for example, preferentially allow acidic gases contained in the gas mixture to pass through. For example, the permeation rate T1 of carbon dioxide passing through the separation membrane 10 is, for example, 10 GPU or more, preferably 50 GPU or more, and more preferably 100 GPU or more. The upper limit of the permeation rate T1 is not particularly limited, and is, for example, 500 GPU. Note that GPU is 10 -6 ·cm 3 (STP) / (sec·cm 2 This means cmHg. 3 (STP) refers to the volume of carbon dioxide at 1 atmosphere and 0°C.

[0094] The permeation rate T1 can be calculated by the following method. First, a mixed gas consisting of carbon dioxide and nitrogen is supplied to the space adjacent to one side of the separation membrane 10 (for example, the main surface 11 on the separation functional layer side of the separation membrane 10), and the space adjacent to the other side of the separation membrane 10 (for example, the main surface 12 on the porous support side of the separation membrane 10) is depressurized. This yields the permeate fluid that has permeated through the separation membrane 10. The weight of the permeate fluid, as well as the volume ratio of carbon dioxide and the volume ratio of nitrogen in the permeate fluid, are measured. The permeation rate T1 can be calculated from the measurement results. In the above operation, the concentration of carbon dioxide in the mixed gas is 50 vol% under standard conditions (0°C, 101 kPa). The mixed gas supplied to the space adjacent to one side of the separation membrane 10 has a temperature of 30°C and a pressure of 0.1 MPa. The space adjacent to the other side of the separation membrane 10 is depressurized so that the pressure in the space is 0.1 MPa lower than the atmospheric pressure in the measurement environment.

[0095] Under the above conditions for measuring the permeation rate T1, the separation coefficient α1 of carbon dioxide relative to nitrogen in the separation membrane 10 is not particularly limited, for example, 20 or more, and preferably 40 or more. The upper limit of the separation coefficient α1 is not particularly limited, for example, 100. The separation coefficient α1 can be calculated from the following formula. However, in the following formula, X A and X B These are the volume ratios of carbon dioxide and nitrogen in the gas mixture, respectively. A and Y B These are the volume ratios of carbon dioxide and nitrogen in the permeate fluid that has passed through the separation membrane 10, respectively. Separation coefficient α1 = (Y A / Y B ) / (X A / X B )

[0096] As described above, the separation membrane 10 of this embodiment suppresses variations in separation performance. Specifically, in this embodiment, the coefficient of variation of the carbon dioxide permeation rate T1 permeating through the separation membrane 10 and the coefficient of variation of the carbon dioxide separation coefficient α1 relative to nitrogen in the separation membrane 10 tend to be small. For example, the coefficient of variation of the carbon dioxide permeation rate T1 permeating through the separation membrane 10 is, for example, less than 0.18, preferably 0.15 or less, more preferably 0.10 or less, and even more preferably 0.05 or less. The lower limit of the coefficient of variation of the permeation rate T1 is not particularly limited, and is, for example, 0.001. The coefficient of variation of the permeation rate T1 can be determined by the following method. First, the separation membrane 10 is cut and at least three test pieces are prepared. For each test piece, the carbon dioxide permeation rate T1 is measured by the method described above. The mean value and standard deviation of the obtained permeation rate T1 are calculated. The ratio of the standard deviation to the mean value can be considered as the coefficient of variation of the permeation rate T1.

[0097] The coefficient of variation of the separation coefficient α1 of carbon dioxide relative to nitrogen in the separation membrane 10 is, for example, 0.50 or less, preferably 0.40 or less, more preferably 0.30 or less, even more preferably 0.20 or less, and particularly preferably 0.10 or less. The lower limit of the coefficient of variation of the separation coefficient α1 is not particularly limited, and is, for example, 0.001. The coefficient of variation of the separation coefficient α1 can be determined by the following method. First, the separation membrane 10 is cut and at least three test pieces are prepared. For each test piece, the separation coefficient α1 is measured by the method described above. The mean and standard deviation of the obtained separation coefficient α1 are calculated. The ratio of the standard deviation to the mean can be considered as the coefficient of variation of the separation coefficient α1.

[0098] Furthermore, the permeation rate T2 of carbon dioxide permeating through the intermediate layer 2 is, for example, 10 GPU or more, preferably 500 GPU or more, more preferably 1000 GPU or more, even more preferably 1100 GPU or more, particularly preferably 1500 GPU or more, especially preferably 2000 GPU or more, and may also be 3000 GPU or more. The upper limit of the permeation rate T2 is not particularly limited, and is, for example, 10000 GPU. The permeation rate T2 can be measured by the same method as the permeation rate T1, except that a laminate of the intermediate layer 2 and the porous support 3 is used instead of the separation membrane 10.

[0099] Under the above conditions for measuring the permeation rate T2, the separation coefficient α2 of carbon dioxide relative to nitrogen in the intermediate layer 2 is not particularly limited, but is, for example, 1 or more, and preferably 5 or more. The upper limit of the separation coefficient α2 is not particularly limited, but is, for example, 20. The separation coefficient α2 can be calculated in the same way as the separation coefficient α1.

[0100] The degree of variation in the separation performance of the separation membrane 10 can be predicted from the degree of variation in the separation performance of the intermediate layer 2. That is, the more the variation in the separation performance of the intermediate layer 2 is suppressed, the more likely it is that the variation in the separation performance of the separation membrane 10 will be suppressed. The coefficient of variation of the carbon dioxide permeation rate T2 permeating through the intermediate layer 2 is, for example, 0.50 or less, preferably 0.40 or less, more preferably 0.30 or less, even more preferably 0.20 or less, and particularly preferably 0.15 or less. The lower limit of the coefficient of variation of the permeation rate T2 is not particularly limited, and is, for example, 0.001. The coefficient of variation of the permeation rate T2 can be determined by the same method as the coefficient of variation of the permeation rate T1, except that a laminate of the intermediate layer 2 and the porous support 3 is used instead of the separation membrane 10.

[0101] The coefficient of variation of the separation coefficient α2 for carbon dioxide relative to nitrogen in the intermediate layer 2 is, for example, 0.40 or less, preferably 0.30 or less, more preferably 0.20 or less, and even more preferably 0.10 or less. The lower limit of the coefficient of variation of the separation coefficient α2 is not particularly limited, and is, for example, 0.001. The coefficient of variation of the separation coefficient α2 can be determined in the same way as the coefficient of variation of the separation coefficient α1, except that a laminate of the intermediate layer 2 and the porous support 3 is used instead of the separation membrane 10.

[0102] In the separation membrane 10 of this embodiment, the peeling force P2 of the separation functional layer 1 to the intermediate layer 2 is not particularly limited, and is, for example, 0.4 N / 10 mm or more, preferably 1.0 N / 10 mm or more, more preferably 2.0 N / 10 mm or more, even more preferably 3.0 N / 10 mm or more, and particularly preferably 4.0 N / 10 mm or more. The greater the peeling force P2, the more likely it is to suppress the peeling of the separation functional layer 1 from the intermediate layer 2 when using the separation membrane 10. The upper limit of the peeling force P2 is not particularly limited, and is, for example, 10.0 N / 10 mm. The peeling force P2 of the separation functional layer 1 to the intermediate layer 2 can be adjusted, for example, by the type and content of the hydrophilic polymer contained in the intermediate layer 2.

[0103] The peel force P2 can be measured by the following method. First, the separation membrane 10 to be evaluated is cut into a 10 mm wide x 50 mm long specimen. Next, the entire surface of the separation functional layer 1 on the specimen is placed on top of a polyethylene terephthalate film via double-sided adhesive tape (No. 500, manufactured by Nitto Denko Corporation), and a 2 kg roller is passed back and forth once to press them together. Next, using a commercially available tensile testing machine, the separation functional layer 1 is peeled off from the intermediate layer 2 together with the film at a peel angle of 90° and a peel speed of 300 mm / min. The peel force at this time is identified as the peel force P2. The above measurement is performed in an atmosphere of 23°C. The double-sided adhesive tape (No. 500) used for measuring the peel force P2 has a greater adhesive strength than the single-sided adhesive tape (No. 7235) used for measuring the peel force P1.

[0104] One application of the separation membrane 10 of this embodiment is the separation of acidic gases from a gas mixture containing acidic gases. Examples of acidic gases in the gas mixture include carbon dioxide, hydrogen sulfide, carbonyl sulfide, sulfur oxides (SOx), hydrogen cyanide, and nitrogen oxides (NOx), with carbon dioxide being preferred. The gas mixture contains other gases besides the acidic gas. Examples of other gases include nonpolar gases such as hydrogen and nitrogen, and inert gases such as helium, with nitrogen being preferred. In particular, the separation membrane 10 of this embodiment is suitable for separating carbon dioxide from a gas mixture containing carbon dioxide and nitrogen. However, the applications of the separation membrane 10 are not limited to the separation of acidic gases from the gas mixture described above.

[0105] <Embodiment of a membrane separation apparatus> As shown in Figure 2, the membrane separation apparatus 100 of this embodiment comprises a separation membrane 10 and a tank 20. The tank 20 comprises a first chamber 21 and a second chamber 22. The separation membrane 10 is located inside the tank 20. Inside the tank 20, the separation membrane 10 separates the first chamber 21 and the second chamber 22. The separation membrane 10 extends from one of a pair of walls of the tank 20 to the other.

[0106] The first chamber 21 has an inlet 21a and an outlet 21b. The second chamber 22 has an outlet 22a. Each of the inlet 21a, outlet 21b, and outlet 22a is, for example, an opening formed in the wall of the tank 20.

[0107] Membrane separation using the membrane separation apparatus 100 is performed, for example, by the following method. First, a mixed gas 30 containing an acidic gas is supplied to the first chamber 21 through the inlet 21a. The concentration of the acidic gas in the mixed gas 30 is not particularly limited, and under standard conditions, it is, for example, 0.01 vol% (100 ppm) or more, preferably 1 vol% or more, more preferably 10 vol% or more, even more preferably 30 vol% or more, and particularly preferably 50 vol% or more. The upper limit of the concentration of the acidic gas in the mixed gas 30 is not particularly limited, and under standard conditions, it is, for example, 90 vol%.

[0108] The pressure inside the first chamber 21 may be increased by supplying the mixed gas 30. The membrane separator 100 may further include a pump (not shown) for increasing the pressure of the mixed gas 30. The pressure of the mixed gas 30 supplied to the first chamber 21 is, for example, 0.1 MPa or more, preferably 0.3 MPa or more.

[0109] The second chamber 22 may be depressurized while the mixed gas 30 is supplied to the first chamber 21. The membrane separation device 100 may further include a pump (not shown) for depressurizing the second chamber 22. The second chamber 22 may be depressurized such that the space inside the second chamber 22 is, for example, 10 kPa or more, preferably 50 kPa or more, and more preferably 100 kPa or more, than the atmospheric pressure in the measurement environment.

[0110] By supplying the mixed gas 30 into the first chamber 21, a permeate fluid 35 with a higher acidic gas content than the mixed gas 30 can be obtained on the other side of the separation membrane 10. That is, the permeate fluid 35 is supplied to the second chamber 22. The permeate fluid 35 mainly contains, for example, an acidic gas. However, the permeate fluid 35 may also contain small amounts of other gases besides acidic gases. The permeate fluid 35 is discharged to the outside of the tank 20 through the outlet 22a.

[0111] The concentration of acidic gas in the gas mixture 30 gradually decreases from the inlet 21a to the outlet 21b of the first chamber 21. The gas mixture 30 (impermeable fluid 36) treated in the first chamber 21 is discharged to the outside of the tank 20 through the outlet 21b.

[0112] The membrane separation apparatus 100 of this embodiment is suitable for a continuous flow membrane separation method. However, the membrane separation apparatus 100 of this embodiment may also be used for a batch membrane separation method.

[0113] <Modified example of a membrane separation device> As shown in Figure 3, the membrane separation device 110 of this embodiment comprises a central tube 41 and a laminate 42. The laminate 42 contains the separation membrane 10. The membrane separation device 110 is a spiral-shaped membrane element.

[0114] The central tube 41 has a cylindrical shape. Multiple holes are formed on the surface of the central tube 41 to allow the permeable fluid 35 to flow into the interior of the central tube 41. Examples of materials for the central tube 41 include resins such as acrylonitrile-butadiene-styrene copolymer resin (ABS resin), polyphenylene ether resin (PPE resin), and polysulfone resin (PSF resin); and metals such as stainless steel and titanium. The inner diameter of the central tube 41 is, for example, in the range of 20 to 100 mm.

[0115] The laminate 42 further includes a supply-side channel material 43 and a permeate-side channel material 44 in addition to the separation membrane 10. The laminate 42 is wound around the central tube 41. The membrane separation device 110 may further include an outer casing material (not shown).

[0116] For the supply-side channel material 43 and the permeate-side channel material 44, for example, a resin net made of polyphenylene sulfide (PPS) or ethylene-chlorotrifluoroethylene copolymer (ECTFE) can be used.

[0117] Membrane separation using the membrane separation device 110 is performed, for example, by the following method. First, a mixed gas 30 is supplied to one end of the wound laminate 42. The permeate fluid 35 that has permeated through the separation membrane 10 of the laminate 42 moves into the center tube 41. The permeate fluid 35 is discharged to the outside through the center tube 41. The mixed gas 30 (impermeable fluid 36) processed by the membrane separation device 110 is discharged to the outside from the other end of the wound laminate 42. This makes it possible to separate acidic gas from the mixed gas 30. [Examples]

[0118] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0119] (Example 1) First, 1.6 g of an aqueous emulsion containing a silicone polymer (POLON-MF-56, manufactured by Shin-Etsu Chemical Co., Ltd.), 0.2 g of an aqueous emulsion containing a urethane polymer as a hydrophilic polymer (NeoRez R-2170, manufactured by DSM Coating Resins Co., Ltd.), and 33.3 g of deionized water for dilution were mixed to prepare 35.0 g of an emulsion resin composition with a solid content of 2 wt%. Next, a coating film was obtained by applying the prepared emulsion resin composition onto a porous support using an applicator (gap: 50 μm). As the porous support, a UF membrane (ultrafiltration membrane) RS-50 (a laminate of a porous PVDF layer and a PET nonwoven fabric) manufactured by Nitto Denko Corporation was used. The coating film was formed on the porous PVDF layer of RS-50. The obtained coating film was dried at 130°C for 10 minutes to form an intermediate layer with a thickness of 1 μm. In the intermediate layer, the content of silicone-based polymer was 90 parts by weight, and the content of urethane-based polymer was 10 parts by weight.

[0120] Next, 0.7 g of polyether block amide resin (Pebax MH1657, manufactured by Arkema) was added to a mixture of 24.0 g of isopropanol and 10.3 g of water, and the mixture was stirred at 80°C for 3 hours to prepare 35.0 g of a coating solution containing the polyether block amide resin at a concentration of 2 wt%. The coating solution contained 0.01 g of a leveling agent (KP-112, manufactured by Shin-Etsu Chemical Co., Ltd.). A coating film was obtained by applying the prepared coating solution onto the intermediate layer using an applicator (gap: 50 μm). Next, the obtained coating film was dried in a 60°C oven for 30 minutes to form a separation functional layer. This obtained the separation film of Example 1.

[0121] (Examples 2-22) Separation membranes of Examples 2 to 22 were obtained by the same method as in Example 1, except that the type of hydrophilic polymer and the polymer content in the intermediate layer were changed as shown in Tables 1 and 2.

[0122] (Example 23) The separation membrane of Example 23 was obtained by the same method as in Example 1, except that the emulsion resin composition did not contain a hydrophilic polymer, the content of the silicone-based polymer in the intermediate layer was changed to 100 parts by weight, and the surface of the intermediate layer was corona-treated before forming the separation functional layer.

[0123] (Reference example 1) The laminate of Reference Example 1 was obtained by the same method as in Example 23, except that corona treatment was not performed on the surface of the intermediate layer and a separation functional layer was not formed.

[0124] (Comparative Example 1) A separation membrane for Comparative Example 1 was obtained by the same method as in Example 23, except that a solution containing a silicone polymer (YSR-3022 from Momentive Performance Materials, Inc.) was used instead of the emulsion resin composition, and the content of the silicone polymer in the intermediate layer was changed to 88 parts by weight. The solution containing the silicone polymer further contained a curing catalyst and a curing retarder, and the curing reaction of the silicone polymer proceeded when the intermediate layer was prepared.

[0125] (Reference example 2) The laminate of Reference Example 2 was obtained by the same method as in Comparative Example 1, except that corona treatment was not performed on the surface of the intermediate layer and a separation functional layer was not formed.

[0126] (Example 24) First, 0.7 g of an aqueous emulsion containing a silicone polymer (POLON-MF-56, manufactured by Shin-Etsu Chemical Co., Ltd.), 1.2 g of an aqueous slurry containing a filler, and 18.1 g of deionized water for dilution were mixed to prepare 20.0 g of an emulsion resin composition with a solid content of 2 wt%. As the aqueous slurry containing the filler, a zeolite aqueous slurry (Zeoal 4A 50 nm aqueous slurry, manufactured by Nakamura Choko Co., Ltd.) was used. Next, a coating film was obtained by applying the prepared emulsion resin composition onto a porous support using an applicator (gap: 100 μm). As the porous support, a UF membrane (ultrafiltration membrane) RS-50 (a laminate of a PVDF porous layer and a PET nonwoven fabric) manufactured by Nitto Denko Corporation was used. The coating film was formed on the PVDF porous layer of RS-50. The obtained coating film was dried at 130°C for 10 minutes to form an intermediate layer with a thickness of 2 μm. In the intermediate layer, the content of the silicone polymer was 70 parts by weight, and the content of the filler was 30 parts by weight.

[0127] Next, 0.7 g of polyether block amide resin (Pebax MH1657, manufactured by Arkema) was added to a mixture of 24.0 g of isopropanol and 10.3 g of water, and the mixture was stirred at 80°C for 3 hours to prepare 35.0 g of a coating solution containing the polyether block amide resin at a concentration of 2 wt%. The coating solution contained 0.01 g of a leveling agent (KP-112, manufactured by Shin-Etsu Chemical Co., Ltd.). A coating film was obtained by applying the prepared coating solution onto the intermediate layer using an applicator (gap: 50 μm). Next, the obtained coating film was dried in a 60°C oven for 30 minutes to form a separation functional layer. This obtained the separation film of Example 24.

[0128] (Examples 25-26) Separation membranes for Examples 25-26 were obtained by the same method as in Example 24, except that the type of filler and the content of polymer and filler in the intermediate layer were changed as shown in Table 4.

[0129] (Example 27) First, the surfactant was diluted 100 times by adding water. BYK-347, manufactured by BY Chemie Japan, was used as the surfactant. Next, 800g of the diluted solution was mixed with 400g of an aqueous emulsion containing a silicone polymer (POLON-MF-56, manufactured by Shin-Etsu Chemical Co., Ltd.) and 900g of deionized water for dilution to prepare 2100g of an emulsion resin composition with a solid content concentration of 8 wt%. Then, a coating film was obtained by applying the prepared emulsion resin composition onto a porous support using a gravure coater (gap: 5 μm). Note that when using a gravure coater, it is necessary to pre-condition the emulsion resin composition on the metal roll. In Example 27, despite the relatively low solid content concentration of 8 wt% in the emulsion resin composition, no repellency of the emulsion resin composition on the metal roll was observed. The thickness of the coating film (coating thickness) was 5 μm. As the porous support, Nitto Denko's UF membrane (ultrafiltration membrane) RS-50 (a laminate of a PVDF porous layer and a PET nonwoven fabric) was used. The coated film was formed on the PVDF porous layer of RS-50. The obtained coated film was dried at 130°C for 2.5 minutes to form an intermediate layer with a thickness of 0.5 μm. In the intermediate layer, the content of silicone polymer was 100 parts by weight and the content of surfactant was 5 parts by weight.

[0130] Next, 30 g of polyether block amide resin (Pebax MH1657, manufactured by Arkema) was added to a mixture of 129 g of isopropanol and 441 g of water, and the mixture was stirred at 80°C for 3 hours to prepare 1500 g of a coating solution containing the polyether block amide resin at a concentration of 2 wt%. The coating solution contained 0.3 g of a leveling agent (KP-112, manufactured by Shin-Etsu Chemical Co., Ltd.). A coating film was obtained by applying the prepared coating solution onto the intermediate layer using an applicator (gap: 50 μm). Next, the obtained coating film was dried in an oven at 80°C for 2.5 minutes to form a separation functional layer. This obtained the separation film of Example 27.

[0131] (Reference example 3) The laminate of Reference Example 3 was obtained by the same method as in Example 23, except that the applicator gap when forming the intermediate layer was set to 100 μm, corona treatment was not performed on the surface of the intermediate layer, and a separation functional layer was not formed.

[0132] [Evaluation of the separation performance of the intermediate layer] The separation performance of the intermediate layer was evaluated for the examples, comparative examples, and reference examples by the following method. First, the laminate of the intermediate layer and porous support obtained before the formation of the separation functional layer was cut, and three test specimens were prepared. For each test specimen, the separation coefficient of carbon dioxide relative to nitrogen α2 (CO2 / N2) and the carbon dioxide permeation rate T2 were measured. In detail, the test specimens were set in a metal cell and sealed with O-rings to prevent leakage. Next, a mixed gas was injected into the metal cell so that the mixed gas contacted the main surface of the test specimen on the intermediate layer side. The mixed gas consisted substantially of carbon dioxide and nitrogen. The concentration of carbon dioxide in the mixed gas was 50 vol% under standard conditions. The mixed gas injected into the metal cell was at a temperature of 30°C and a pressure of 0.1 MPa. Next, the space in the metal cell adjacent to the main surface of the test specimen on the porous support side was depressurized with a vacuum pump. At this time, the pressure in this space was depressurized to 0.1 MPa less than the atmospheric pressure in the measurement environment. This resulted in the acquisition of a permeable fluid. Based on the composition and weight of the obtained permeate fluid, the separation coefficient α2 and the carbon dioxide permeation rate T2 of the test specimens were calculated. Furthermore, the coefficients of variation of the separation coefficient α2 and the permeation rate T2 were determined based on the separation coefficient α2 and permeation rate T2 of all test specimens. In Examples 1 to 27 and Reference Examples 1 and 3, the coefficients of variation of the separation coefficient α2 and the permeation rate T2 in the intermediate layer were all 0.20 or less. On the other hand, in Comparative Example 1 and Reference Example 2, the coefficients of variation of the separation coefficient α2 and the permeation rate T2 in the intermediate layer were significantly higher than 0.20, being 0.50 or higher. Tables 1 to 4 show the average values ​​of the obtained separation coefficient α2 and permeation rate T2.

[0133] [Evaluation of separation performance of separation membranes] For Examples 1, 4, 24-27 and Comparative Example 1, the separation performance of the separation membrane was also evaluated. The evaluation of the separation performance of the separation membrane was carried out in the same manner as the evaluation of the separation performance of the intermediate layer, except that the separation membrane was used instead of the laminate of the intermediate layer and porous support. As a result, the separation coefficient α1 (CO2 / N2) of carbon dioxide relative to nitrogen and the permeation rate T1 of carbon dioxide were measured for three test pieces prepared by cutting the separation membrane. Table 5 shows the average values ​​and coefficients of variation for the obtained separation coefficient α1 and permeation rate T1. Table 5 also shows the average values ​​and coefficients of variation for the separation coefficient α2 and permeation rate T2 in the intermediate layer for Examples 1, 4, 24-27, Comparative Example 1 and Reference Example 2.

[0134] [Contact angle with water] For Examples 1-23, Comparative Example 1, and Reference Examples 1-2, the contact angle with water on the surface of the intermediate layer was measured using the method described above. For the measurement, a laminate of the intermediate layer and porous support obtained before the formation of the separation functional layer was used. The results are shown in Tables 1-3.

[0135] [Peel force P1 of the intermediate layer on a porous support] For Examples 1-23, Comparative Example 1, and Reference Examples 1-2, the peel force P1 of the intermediate layer to the porous support was measured using the method described above. For the measurement, a laminate of the intermediate layer and the porous support obtained before the formation of the separation functional layer was used. The results are shown in Tables 1-3.

[0136] [Peel force P2 of the separation functional layer relative to the intermediate layer] For the separation membranes of Examples 1 to 23 and Comparative Example 1, the peeling force P2 of the separation functional layer relative to the intermediate layer was measured using the method described above. The results are shown in Tables 1 to 3.

[0137] [Observation of defects in the intermediate layer and separation layer] For Comparative Example 1, the surface of the intermediate layer was observed with an electron microscope before the formation of the separation functional layer. The results are shown in Figure 4A. As can be seen from Figure 4A, defects (pinholes) were found on the surface of the intermediate layer in Comparative Example 1.

[0138] Furthermore, a staining solution was applied to the separation functional layer of the separation membrane of Comparative Example 1. At this time, the staining solution penetrated into the separation functional layer at the locations where defects (pinholes) existed, staining those locations in the separation functional layer. The results are shown in Figure 4B. As can be seen from Figure 4B, in Comparative Example 1, defects were also created in the separation functional layer because the separation functional layer was formed on top of the defective intermediate layer.

[0139] [Table 1]

[0140] [Table 2]

[0141] [Table 3]

[0142] [Table 4]

[0143] [Table 5]

[0144] The abbreviations used in Tables 1-4 are as follows: MF-56: POLON-MF-56 manufactured by Shin-Etsu Chemical Co., Ltd. YSR-3022: YSR-3022 manufactured by Momentive Performance Materials. R-2170: NeoRez R-2170 manufactured by DSM Coating Resins. DA200: Aracoat DA200 manufactured by Arakawa Chemical Industries Co., Ltd. SF470: Superflex 470 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. WLS213: A Hydrant WLS213 manufactured by DIC Corporation. SF420: Superflex 420 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. AP4690N: Polysol AP4690N manufactured by Showa Denko Corporation. WHW-822: Ceranate WHW-822 manufactured by DIC Corporation KT-8803: Elitel KT-8803 manufactured by Unitika Corporation EVA P-3N: Polysol EVA P-3N manufactured by Showa Denko Corporation. 4A: Zeoal 4A 50nm aqueous slurry manufactured by Nakamura Superhard Co., Ltd. (Solid content concentration 10wt%, average particle size 50nm, average pore size 0.4nm, density approximately 2g / cm³) 3 ) ZSM-5: Zeoal ZSM-5 aqueous slurry manufactured by Nakamura Choko Co., Ltd. (Solid content concentration 30 wt%, average particle size 100 nm, average pore size 0.54~0.56 nm, density approximately 2 g / cm³) 3 ) AEROSILOX50: AEROSILOX50 manufactured by Japan Aerosil Co., Ltd. BYK-349: BYK-349 manufactured by Big Chemie Japan Co., Ltd.

[0145] As described above, in Examples 1 to 27, the coefficient of variation of the separation coefficient α2 and the coefficient of variation of the permeation rate T2 in the intermediate layer were all smaller than those in Comparative Example 1, being 0.20 or less. Furthermore, as can be seen from Table 5, in Examples 1, 4, and 24-27, where the variation in separation performance in the intermediate layer was suppressed, the coefficient of variation of the separation coefficient α1 and the coefficient of variation of the permeation rate T1 in the separation membrane also tended to be smaller than those in Comparative Example 1. From the results in Table 5, it can be inferred that the variation in separation performance was also suppressed in the separation membranes of the other examples compared to Comparative Example 1. It should be noted that, as can be seen from Examples 24-26, the permeation rate T2 of carbon dioxide tended to be higher in the intermediate layer containing filler compared to Reference Example 3. [Industrial applicability]

[0146] The separation membrane of this embodiment is suitable for separating acidic gases from a gas mixture containing acidic gases. In particular, the separation membrane of this embodiment is suitable for separating carbon dioxide from off-gas in chemical plants or thermal power plants.

Claims

1. Separation functional layer, A porous support that supports the separation functional layer, Displaced between the separation functional layer and the porous support, an intermediate layer formed from an emulsion resin composition, Equipped with, The intermediate layer comprises a silicone polymer and a hydrophilic polymer. A separation membrane in which the content of the hydrophilic polymer in the intermediate layer is 10 wt% to 20 wt%.

2. Separation functional layer, A porous support that supports the separation functional layer, Displaced between the separation functional layer and the porous support, an intermediate layer formed from an emulsion resin composition, Equipped with, The intermediate layer comprises a silicone polymer and a hydrophilic polymer. The emulsion resin composition is a separation membrane containing water as a dispersion medium.

3. Separation functional layer, A porous support that supports the separation functional layer, Displaced between the separation functional layer and the porous support, an intermediate layer formed from an emulsion resin composition, Equipped with, The intermediate layer comprises a silicone polymer and a hydrophilic polymer. The emulsion resin composition comprises a separation membrane containing a surfactant.

4. Separation functional layer, A porous support that supports the separation functional layer, Displaced between the separation functional layer and the porous support, an intermediate layer formed from an emulsion resin composition, Equipped with, The intermediate layer comprises a silicone polymer and a hydrophilic polymer. A separation membrane used to separate carbon dioxide from a mixture of gases containing carbon dioxide and nitrogen.

5. The separation membrane according to any one of claims 1 to 4, wherein the hydrophilic polymer comprises at least one selected from the group consisting of urethane polymers, (meth)acrylic polymers, (meth)acrylic urethane polymers, ester polymers, and vinyl ester polymers.

6. The separation membrane according to any one of claims 2 to 4, wherein the content of the hydrophilic polymer in the intermediate layer is 10 wt% to 20 wt%.

7. The separation membrane according to any one of claims 1, 3, or 4, wherein the emulsion resin composition contains water as a dispersion medium.

8. The separation membrane according to any one of claims 1, 2, or 4, wherein the emulsion resin composition comprises a surfactant.

9. The separation membrane according to claim 3 or 8, wherein the ratio of the weight of the surfactant to the total weight of all solids in the emulsion resin composition is 15 wt% or less.

10. The separation membrane according to any one of claims 1 to 9, wherein the intermediate layer includes a filler.

11. The separation membrane according to claim 10, wherein the filler has a particle shape and its average particle diameter is smaller than the thickness of the intermediate layer.

12. The separation membrane according to any one of claims 1 to 11, wherein the separation functional layer comprises a polyether block amide resin.

13. The separation membrane according to any one of claims 1 to 12, wherein the porous support comprises polyvinylidene fluoride.

14. The separation membrane according to any one of claims 1 to 13, wherein the thickness of the intermediate layer is 10 μm or less.

15. The separation membrane according to any one of claims 1 to 14, wherein the peeling force of the separation functional layer to the intermediate layer is 3.0 N / 10 mm or more.

16. A separation membrane according to any one of claims 1 to 3, used for separating carbon dioxide from a mixed gas containing carbon dioxide and nitrogen.

17. A method for manufacturing a separation membrane comprising: a separation functional layer; a porous support supporting the separation functional layer; and an intermediate layer disposed between the separation functional layer and the porous support, the intermediate layer containing a silicone polymer and a hydrophilic polymer, The aforementioned manufacturing method is The process involves applying an emulsion resin composition onto the porous support to form a coating film, The coating film is dried to form the intermediate layer, A method for producing a separation membrane, including the following:

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