CN116997408A

CN116997408A - Separation membrane and method for producing same

Info

Publication number: CN116997408A
Application number: CN202280019781.1A
Authority: CN
Inventors: 佐山俊亮; 谷贤辅
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2021-03-09
Filing date: 2022-01-12
Publication date: 2023-11-03

Abstract

The invention provides a separation membrane suitable for inhibiting the deviation of separation performance. The separation membrane 10 of the present invention includes a separation functional layer 1, a porous support 3 supporting the separation functional layer 1, and an intermediate layer 2 which is disposed between the separation functional layer 1 and the porous support 3 and is formed of an emulsion resin composition. The emulsion resin composition contains, for example, a silicone polymer, a hydrophilic polymer, and the like.

Description

Separation membrane and method for producing same

Technical Field

The present invention relates to a separation membrane and a method for producing the same.

Background

As a method for separating an acid gas from a mixed gas containing the acid gas such as carbon dioxide, a membrane separation method has been developed. Compared with an absorption method in which an acid gas contained in a mixed gas is absorbed into an absorbent and separated, the membrane separation method can effectively separate the acid gas while suppressing the operation cost.

As a separation membrane used in the membrane separation method, a composite membrane in which a separation functional layer is formed on a porous support is exemplified. In the field of separation membranes, in order to reduce the thickness of the separation functional layer, an intermediate layer may be disposed between the separation functional layer and the porous support (for example, patent documents 1 and 2).

Prior art literature

Patent literature

Patent document 1: japanese patent No. 6186286

Patent document 2: japanese patent application laid-open No. 2019-209474

Disclosure of Invention

Problems to be solved by the application

In the conventional separation membrane, it is required to suppress the variation in separation performance due to the measurement site.

Accordingly, the present application provides a separation membrane suitable for suppressing variation in separation performance.

Means for solving the problems

The intermediate layer can be produced, for example, by applying a solution containing an intermediate layer material to a porous support and drying the resulting coating film. However, according to the studies of the present inventors, when the above-mentioned solution is applied to a porous support, the solution tends to penetrate into the porous support. If the solution penetrates into the porous support, there are cases where defects occur in the formed intermediate layer as well as variations in the thickness of the intermediate layer. The inventors of the present application have newly found that, in the case where a separation functional layer is further formed on an intermediate layer formed by the above-described method, a deviation occurs in separation performance of a separation film, and have completed the present application.

The present application provides a separation membrane, comprising:

separating the functional layer;

A porous support for supporting the separation functional layer; and

an intermediate layer which is disposed between the separation functional layer and the porous support and is formed of an emulsion resin composition.

The present invention also provides a method for producing a separation membrane comprising a separation functional layer, a porous support for supporting the separation functional layer, and an intermediate layer disposed between the separation functional layer and the porous support,

the manufacturing method comprises the following steps:

coating an emulsion resin composition on the porous support to form a coating film; and

the coating film is dried to form the intermediate layer.

The present invention also provides a separation membrane comprising:

separating the functional layer;

a porous support for supporting the separation functional layer; and

an intermediate layer which is disposed between the separation functional layer and the porous support and contains a silicone polymer and a hydrophilic polymer.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a separation membrane suitable for suppressing variation in separation performance can be provided.

Drawings

Fig. 1 is a cross-sectional view schematically showing a separation membrane according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a membrane separation device provided with a separation membrane according to the present invention.

Fig. 3 is a perspective view schematically showing a modification of the membrane separation device having the separation membrane of the present invention.

Fig. 4A is an electron microscopic image of the surface of the intermediate layer at a stage before the formation of the separation functional layer in the separation membrane of comparative example 1.

Fig. 4B is an image showing a state after the dye solution was applied on the separation functional layer of the separation membrane of comparative example 1.

Detailed Description

The following describes the present invention in detail, but the gist of the following description is not intended to limit the present invention to specific embodiments.

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 directly contacts the separation functional layer 1 and the porous support 3. The intermediate layer 2 is formed of an emulsion resin composition.

(separation functional layer)

The separation functional layer 1 is, for example, a layer that can preferentially permeate the acid gas contained in the mixed gas. In a preferred embodiment, the separation functional layer 1 contains a resin. Examples of the resin contained in the separation functional layer 1 include polyether block amide resins, polyamide resins, polyether resins, polyimide resins, cellulose acetate resins, silicone resins, and fluorine resins. The separation functional layer 1 preferably contains a polyether block amide resin. In this embodiment, the separation functional layer 1 is preferably substantially formed of a resin. In the present specification, "substantially consist of" means that other components that change the essential characteristics of the material mentioned are excluded, and means that, for example, 95wt% or more, and further 99wt% or more of the material is constituted. The separation functional layer 1 may contain an additive such as a leveling agent in addition to the resin.

In another preferred embodiment, the separation functional layer 1 contains an ionic liquid. The separation functional layer 1 has, for example, a double network gel containing an ionic liquid. The double-network gel is a gel having 2 kinds of mesh structures independent of each other. The double-network gel includes, for example, a 1 st mesh structure mainly composed of an organic material, a 2 nd mesh structure mainly composed of an inorganic material, and an ionic liquid. In the present specification, "mainly composed of … …" means that 50wt% or more, and further 70wt% or more of the material is composed.

The organic material for forming the 1 st mesh structure includes, for example, a polymer such as polyacrylamide (in particular, polydialkylacrylamide such as polydimethylacrylamide). The polymer contained in the organic material has a structural unit derived from an acrylamide derivative, and may further contain a crosslinked structure. The polymer having a crosslinked structure can be produced by a known method. For example, first, a prepolymer having a structural unit having an N-hydroxysuccinimide ester group is prepared. The structural unit having an N-hydroxysuccinimide ester group is derived from, for example, N-acryloyloxy succinimide. Then, the prepolymer is reacted with an amine-based crosslinking agent to obtain a polymer having a crosslinked structure. The amine-based crosslinking agent is a compound having 2 or more primary amino groups, and is, for example, ethylene glycol bis (3-aminopropyl) ether.

The 2 nd mesh structure may comprise a network of a plurality of particles. The network of the plurality of particles is formed, for example, by the plurality of particles being bonded to each other through hydrogen bonds. The particles contained in the 2 nd mesh structure may contain an inorganic material or an organic material. Examples of the inorganic material contained in the particles include silica, titania, and alumina. As an example, the particles contained in the 2 nd mesh structure are silica particles.

In this embodiment, examples of the ionic liquid include ionic liquids having an imidazolium, pyridinium, ammonium or phosphonium, and a substituent having 1 or more carbon atoms.

In the ionic liquid having an imidazolium and a substituent having 1 or more carbon atoms, examples of the substituent having 1 or more carbon atoms include an alkyl group having 1 or more and 20 or less carbon atoms, a cycloalkyl group having 3 or more and 14 or less carbon atoms, an aryl group having 6 or more and 20 or less carbon atoms, and the like, and they may be further substituted with a hydroxyl group, a cyano group, an amino group, a monovalent ether group, and the like (for example, a hydroxyalkyl group having 1 or more and 20 or less carbon atoms, and the like).

Examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a n-propyl group, a n-butyl group, a n-pentyl group, a n-hexyl group, a n-heptyl group, a n-octyl group, a n-nonyl group, a n-decyl group, a n-undecyl group, a n-dodecyl group, a n-tridecyl group, a n-tetradecyl group, a n-pentadecyl group, a n-hexadecyl group, a n-heptadecyl group, a n-octadecyl group, a n-nonadecyl group, a n-eicosyl group, an isopropyl group, a sec-butyl group, an isobutyl group, a 1-methylbutyl group, a 1-ethylpropyl group, a 2-methylbutyl group, an isopentyl group, a neopentyl group, a 1, 2-dimethylpropyl group, a 1-dimethylpropyl group, a tert-pentyl group, a 2-ethylhexyl group, a 1, a 5-dimethylhexyl group, and the like, and may be further substituted with a hydroxyl group, a cyano group, an amino group, a monovalent ether group, and the like.

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

Examples of the cycloalkyl group having 3 to 14 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclododecyl, norbornyl, bornyl, adamantyl and the like, and they may be further substituted with a hydroxyl group, cyano group, amino group, monovalent ether group and the like.

Examples of the aryl group having 6 to 20 carbon atoms include phenyl group, tolyl group, xylyl group, mesityl group, methoxyphenyl group, naphthyl group, benzyl group, etc., which may be further substituted with hydroxyl group, cyano group, amino group, monovalent ether group, etc.

The compound having a substituent of 1 or more carbon atoms and imidazolium may further have a substituent such as an alkyl group, or may form a salt with a counter anion. Examples of the counter anion include alkylsulfate, tosylate, methanesulfonate, acetate, bis (fluorosulfonyl) imide, bis (trifluoromethanesulfonyl) imide, thiocyanate, dicyandiamide, tricyanomethane (tricyanide), tetracyanoborate, hexafluorophosphate, tetrafluoroborate, and halide (halide), and bis (fluorosulfonyl) imide, bis (trifluoromethanesulfonyl) imide, dicyandiamide, tricyanomethane, and tetracyanoborate are preferable from the viewpoint of gas separation performance.

Specific examples of the ionic liquid having an imidazolium and a substituent having 1 or more carbon atoms include 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide salt, 1-ethyl-3-methylimidazolium dicyanide salt, 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoromethane sulfonate, 1-butyl-3-methylimidazolium tetrachloroferrate, 1-butyl-3-methylimidazolium iodide, 1-butyl-2, 3-dimethylimidazolium chloride, 1-butyl-2, 3-dimethylimidazolium hexafluorophosphate, 1-butyl-2, 3-dimethylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt, 1-butyl-2, 3-dimethylimidazolium bis (trifluoromethanesulfonyl) imide salt, 1-butyl-3-dimethylimidazolium bis (trifluoromethanesulfonyl) sulfide salt, 1-butyl-3-methylimidazolium chloride, 1-3-dimethylimidazolium bromide, 1-dimethylimidazolium chloride, 1-butylimidazolium bromide, and 1-dimethylimidazolium bromide salt 1, 3-bis (2, 6-diisopropylphenyl) imidazolium chloride, 1, 3-diisopropylimidazolium tetrafluoroborate, 1, 3-di-tert-butylimidazolium 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-methyl-3-n-octylimidazolium chloride, 1-methyl-3-n-octylimidazolium hexafluorophosphate, 1-methyl-3- [6- (methylsulfinyl) hexyl ] imidazolium p-toluenesulfonate, 1-ethyl-3-methylimidazolium tricyanomethanate, 1- (2-hydroxyethyl) -3-methylimidazolium bis (trifluoromethanesulfonyl) amine salt and the like.

Among them, 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide salt ([ EMI ] is particularly preferable from the viewpoint of gas separation performance][FSI]) 1-ethyl-3-methylimidazolium dicyanoamine salt ([ EMI ]][DCA]) 1-ethyl-3-methylimidazolium tricyanomethanate ([ EMI)][TCM]) 1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt ([ C) ₄ mim][TF ₂ N]) 1- (2-hydroxyethyl) -3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt ([ C) ₂ OHim][TF ₂ N])。

The method for producing the double network gel is not particularly limited, and for example, the method disclosed in e.kamio et al, adv.mate, 29,1704118 (2017) can be used.

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

The content of the 1 st mesh structure mainly composed of an organic material in the double-network gel is, for example, 1wt% or more, preferably 5wt% or more, and more preferably 10wt% or more. The upper limit of the content of the 1 st mesh structure is, for example, 15wt%. The content of the 2 nd mesh structure mainly composed of an inorganic material in the double-network gel is, for example, 1wt% or more from the viewpoint of improving the double-network gel strength. The upper limit of the content of the 2 nd mesh structure is, for example, 5wt%. The ratio of the total of the weight of the 1 st mesh structure and the weight of the 2 nd mesh structure to the weight of the double-network gel is, for example, 2wt% or more, preferably 5wt% or more, and more preferably 10wt% or more. The ratio is preferably 20wt% or less. In this embodiment, the separation functional layer 1 is preferably formed substantially of a double network gel.

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 be 10 μm or less, may be 5.0 μm or less, or may be 2.0 μm or less, depending on the case. The thickness of the separation functional layer 1 may be 0.05 μm or more and may be 0.1 μm or more.

(intermediate layer)

As described above, in the present embodiment, the intermediate layer 2 is formed of the emulsion resin composition. The emulsion resin composition refers to a liquid containing a dispersion medium and a polymer emulsified in the dispersion medium. The emulsion resin composition preferably contains water as a dispersion medium. That is, the emulsion resin composition is preferably an emulsion of the oil-in-water droplet type (O/W type). The emulsion resin composition may contain an organic solvent as a dispersion medium instead of water or together with water. Examples of the organic solvent contained in the emulsion resin composition include 2-ethylhexanol, butyl cellosolve, dipropylene glycol, ethylene glycol, propylene glycol, n-propanol, and isopropanol, and ethylene glycol and propylene glycol are preferable from the viewpoint of dispersibility of the polymer in the emulsion resin composition.

The emulsion resin composition contains, for example, a silicone polymer. The silicone polymer has, for example, a structural unit a represented by the following formula (1).

[ chemical formula 1]

In the formula (1), R ¹ R is R ² Independently of one another, a hydrogen atom or a hydrocarbon radical. The hydrocarbon group may be linear or branched. The number of carbon atoms of the hydrocarbon group is not particularly limited, and is, 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 the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl and the like. The hydrocarbon group may be an unsaturated hydrocarbon group such as a vinyl group. R is R ¹ R is R ² Preferably a hydrogen atom, methyl, ethyl or vinyl.

The number of the structural units a included in the silicone polymer is not particularly limited, and is, for example, 100 to 100000, preferably 200 to 90000, and more preferably 500 to 80000.

The silicone polymer contains, for example, the structural unit a as a main component, and is preferably formed substantially only of the structural unit a. In the present specification, the term "main component" means that the largest amount of structural units is contained by weight among all structural units constituting the silicone polymer. The silicone polymer may further contain a structural unit other than the structural unit a.

Specific examples of the silicone polymer include dimethylpolysiloxane. The silicone polymer may be a cyclic siloxane represented by the following formula (2).

[ chemical formula 2]

In the formula (2), R ¹ R is R ² The same as in formula (1). n is not particularly limited, and is, for example, 100 to 100000, preferably 200 to 90000, and more preferably 500 to 80000.

The weight average molecular weight of the silicone polymer is not particularly limited, and is, for example, 1×10 ⁴ ～1×10 ⁶ 。

In the emulsion resin composition, the silicone polymer is dispersed in the form of particles, for example. The average particle diameter of the silicone polymer is not particularly limited, and is, for example, 10 to 1000nm, preferably 50 to 800nm. In the present specification, the average particle diameter refers to a median particle diameter determined based on a particle size distribution measured by a particle size distribution measuring apparatus based on a laser diffraction/scattering method. Specifically, the average particle diameter of the silicone polymer may be determined in accordance with ISO 13320:2009 "particle size analysis-laser diffraction method" was measured using a laser diffraction/scattering particle size distribution measuring apparatus (for example, LS13 320 manufactured by Beckman Coulter).

The method for producing the emulsion resin composition containing the silicone polymer is not particularly limited, and known methods disclosed in JP-A2004-339283 and the like can be appropriately used.

The emulsion resin composition may further contain a surfactant for dispersing the silicone-based polymer. Examples of the surfactant include: anionic surfactants such as alkyl sulfate, alkylbenzenesulfonate and alkyl phosphate; nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether and polyoxyethylene fatty acid ester; cationic surfactants such as quaternary ammonium salts and alkylamine acetates; amphoteric surfactants such as alkyl betaines and alkyl imidazolines. In particular, from the viewpoint of dispersion stability of the silicone polymer, nonionic surfactants such as polyoxyethylene alkyl ether and polyoxyethylene alkylphenyl ether are preferably used. Specific examples of the nonionic surfactant 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 styrenated phenyl ether. The surfactant may be used alone or in combination of 2 or more.

The emulsion resin composition may contain a hydrophilic polymer instead of the silicone-based polymer or together with the silicone-based polymer. In the present specification, the "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. As the contact angle with water, a sheet composed of a polymer as an evaluation target can be used, using Japanese Industrial Standard (JIS) R3257:1999, and evaluated by the still drop method specified in 1999. The lower limit of the contact angle of the hydrophilic polymer with water is not particularly limited, and may be, for example, 30 °, 50 °, or 74.0 °.

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

Examples of the urethane polymer include polyurethane obtained by reacting a polyol with a polyisocyanate, and modified products thereof. The urethane polymer may be a urethane prepolymer having an isocyanate group or a blocked isocyanate group at the end.

Examples of the polyol include: polyether polyols such as polyethylene glycol, polypropylene glycol, and polyoxytetramethylene ether glycol obtained by ring-opening polymerization of ethylene oxide, propylene oxide, tetrahydrofuran, and the like; saturated or unsaturated low molecular diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1, 2-propanediol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1, 5-pentanediol, 1, 6-hexanediol, octanediol, 1, 4-butanediol, dipropylene glycol, bisphenol A propylene oxide adduct, bisphenol A ethylene oxide adduct, hydrogenated bisphenol A, and the like; polyester polyols obtained by dehydration-condensing the low-molecular diols 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, suberic acid, and the like, or anhydrides corresponding thereto; polyester polyols obtained by ring-opening polymerization of lactones such as epsilon-caprolactone and beta-methyl-delta-valerolactone; high molecular polyols generally used for the production of polyurethane, such as polycarbonate polyols and polybutadiene diols. Instead of the low molecular diols, various polyols such as glycerol, trimethylolpropane, trimethylolethane, 1,2, 6-hexanetriol, 1,2, 4-butanetriol, pentaerythritol, and sorbitol may be used. From the viewpoint of dispersibility in the emulsion resin composition, the polyol preferably has a hydrophilic moiety such as an ethylene oxide adduct.

As the polyisocyanate, aromatic, aliphatic or alicyclic diisocyanates can be used. Examples of the diisocyanate include 1, 5-naphthalene diisocyanate, 4' -diphenylmethane diisocyanate, 4' -dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1, 3-phenylene diisocyanate, 1, 4-phenylene diisocyanate, toluene diisocyanate, butane-1, 4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, cyclohexane-1, 4-diisocyanate, phenylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4, 4' -diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate, and dimeric diisocyanate obtained by converting the carboxyl group of a dimer acid into an isocyanate group.

Examples of the blocking agent for isocyanate groups include bisulfites, phenols containing sulfonic acid groups, alcohols, lactams, oximes, and active methylene compounds.

In order to improve dispersibility in the emulsion resin composition, hydrophilic groups such as carboxylate may be introduced into the urethane polymer.

The (meth) acrylic polymer has, for example, a structural unit derived from an alkyl (meth) acrylate as a main component. In the present specification, "(meth) acrylate" means acrylate and/or methacrylate.

The alkyl group included in the alkyl (meth) acrylate is not particularly limited, and is, for example, a linear, branched or cyclic alkyl group having 2 to 14 carbon atoms.

Examples of the alkyl (meth) acrylate include alkyl acrylates having an alkyl group having 2 to 14 carbon atoms, and preferably alkyl acrylates having an alkyl group having 4 to 9 carbon atoms. Examples of the alkyl acrylate include n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, isopentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, nonyl acrylate, and isononyl acrylate.

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

The alkyl (meth) acrylate may be used alone or in combination of two or more. The content of the structural unit derived from the alkyl (meth) acrylate in the (meth) acrylic polymer is not particularly limited, and is, for example, 70 to 100wt%, preferably 85 to 99wt%, and more preferably 87 to 99wt%.

The (meth) acrylic polymer may further comprise structural units derived from a comonomer capable of copolymerizing with the alkyl (meth) acrylate. Examples of the comonomer 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) acrylate having an alkyl group having 1 or 15 carbon atoms or more; 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 methyl glycidyl (meth) acrylate; hydroxy group-containing (meth) acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; nitrogen atom-containing monomers such as (meth) acrylamide, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-methylolpropane (meth) acrylamide, (meth) acryloylmorpholine, aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate; an alkoxy group-containing monomer such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; functional monomers such as 2-methacryloxyethyl isocyanate; olefin monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; vinyl ether monomers such as vinyl ether; monomers containing halogen atoms such as vinyl chloride; vinyl-containing heterocyclic compounds such as N-vinylpyrrolidone, N- (1-methylvinyl) pyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyridine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, and N-vinylmorpholine; n-vinylcarboxylic acid amides; maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide and N-phenylmaleimide; an itaconimide monomer such as N-methyl itaconimide, N-ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexyl itaconimide, N-cyclohexyl itaconimide and N-month Gui Jiyi itaconimide; succinimide-based monomers such as N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, and N- (meth) acryloyl-8-oxyoctamethylene succinimide; sulfonic acid group-containing monomers such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloyloxy naphthalene sulfonic acid; a phosphate group-containing monomer; glycol-based acrylate monomers such as polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate; acrylic acid ester monomers containing a heterocyclic ring or a halogen atom such as tetrahydrofurfuryl (meth) acrylate and fluoro (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, propylene glycol di (meth) acrylate, and the like; esterification products of (meth) acrylic acid with a polyhydric alcohol, 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, dipentaerythritol hexa (meth) acrylate, and the like; polyfunctional vinyl compounds such as divinylbenzene; compounds having a reactive unsaturated double bond such as allyl (meth) acrylate and vinyl (meth) acrylate.

Examples of the urethane (meth) acrylate polymer include a reactant of a (meth) acrylic polyol and a polyisocyanate. Examples of the (meth) acrylic polyol include (meth) acrylic polymers containing structural units derived from (meth) acrylic esters containing hydroxyl groups. Examples of the hydroxyl group-containing (meth) acrylate include those described above for the (meth) acrylic polymer. The polyisocyanate may be any of the polyisocyanates described above for the urethane polymer. The polyisocyanate may be a urethane prepolymer having isocyanate groups.

Examples of the ester polymer include a polymer obtained by polycondensing a dicarboxylic acid and a diol. Examples of the dicarboxylic acid include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, 2-methyl terephthalic acid, 5-sulfoisophthalic acid, 4' -diphenyldicarboxylic acid, 4' -diphenylether dicarboxylic acid, 4' -diphenylketone dicarboxylic acid, 4' -diphenoxyethane dicarboxylic acid, 4' -diphenylsulfone dicarboxylic acid, 1, 4-naphthalene dicarboxylic acid, 1, 5-naphthalene dicarboxylic acid, 2, 6-naphthalene dicarboxylic acid, and 2, 7-naphthalene dicarboxylic acid; 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, fumaric acid, etc.; their derivatives (e.g., lower alkyl esters of dicarboxylic acids, etc.). They may be used singly or in combination of two or more.

Examples of the diol 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-cyclohexanedimethanol, and 1, 4-cyclohexanedimethanol; aromatic diols such as xylylene alcohol, 4 '-dihydroxybiphenyl, 2-bis (4' -hydroxyphenyl) propane, and bis (4-hydroxyphenyl) sulfone. They may be used singly or in combination of two or more.

The vinyl ester polymer has, for example, a structural unit derived from a vinyl ester. Examples of the vinyl ester include vinyl acetate and vinyl propionate. The vinyl ester polymer may further have a structural unit derived from an olefin such as ethylene or propylene. Specific examples of the vinyl ester polymer are ethylene-vinyl acetate copolymers.

The weight average molecular weight of the hydrophilic polymer is not particularly limited, and is, for example, 1X 10 ⁴ ～1×10 ⁷ 。

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

The emulsion resin composition containing the hydrophilic polymer can be produced, for example, by emulsion polymerizing monomer components for forming the hydrophilic polymer in the presence of an emulsifier (surfactant).

The emulsion resin composition may further comprise a surfactant for dispersing the hydrophilic polymer. Examples of the surfactant include those described above for the silicone polymer.

The emulsion resin composition may further contain a surfactant other than the surfactant for dispersing the silicone polymer or the hydrophilic polymer described above. The wettability of the emulsion resin composition to a metal roll provided in a coater such as a gravure coater can be improved by other surfactants depending on the type of the surfactant. Therefore, when the emulsion resin composition contains another surfactant, the emulsion resin composition tends to be uniformly coated by using a coater having a metal roll. By uniformly coating the emulsion resin composition, the variation in thickness of the intermediate layer 2 formed from the emulsion resin composition tends to be suppressed.

Examples of the other surfactant include silicone surfactants. The silicone surfactant includes, for example, a modified polysiloxane having a hydrophilic group. Examples of the hydrophilic group include a hydroxyl group, a carboxylic acid group, a sulfonic acid group, a (meth) acrylic group, an ester group, and an ether group. Specific examples of the modifying group of the modified polysiloxane include- (CH) ₂ CH ₂ O) _n R (n is an integer of 5 to 30, R is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), -and (c) a catalyst comprising a catalyst having a catalyst of the formula (I)(CH ₂ CHOHCH ₂ ) _n -H (n is an integer of 5 to 30), and the like. Specific examples of the modified polysiloxane include polyether modified polydimethyl siloxane. As the Silicone-based surfactant, BYK series made by BYK-Chemie Japan, toray Silicone series made by Dow Corning Toray, TSF series made by Momentive Performance Materials, KP series made by singe Silicone company, KF series, and the like are commercially available.

BYK-349 is an example of the "BYK" series manufactured by BYK-Chemie Japan. BYK-349 tends to suppress the decrease in the transmission rate of carbon dioxide through the intermediate layer 2. BYK-349 has high dispersibility in water and is suitable for emulsion resin compositions containing water as a dispersing medium.

The emulsion resin composition may further contain a crosslinking agent for crosslinking the silicone polymer and the hydrophilic polymer. For example, the emulsion resin composition may contain a water-insoluble crosslinking agent for crosslinking a (meth) acrylic polymer having a structural unit derived from a carboxyl group-containing monomer. The water-insoluble crosslinking agent is, for example, a water-insoluble compound having 2 or more (for example, 2 to 6, preferably 3 to 5) functional groups capable of reacting with carboxyl groups. In the present specification, water-insoluble means that the weight of the compound soluble in 100 parts by weight of water at 25 ℃ is 5 parts by weight or less, preferably 3 parts by weight or less, and more preferably 2 parts by weight or less. The weight of the water-soluble compound can be measured by the following method. First, the same weight of water (25 ℃) was mixed with the compound and stirred at 300rpm for 10 minutes using a stirrer. The resulting mixture was separated into an aqueous phase and an oil phase by centrifugation. The aqueous phase was then removed and dried at 120℃for 1 hour. The weight of the non-volatile component in the aqueous phase (the weight of the compound capable of being dissolved in 100 parts by weight of water) was calculated from the amount of the reduced drying.

The functional group capable of reacting with a carboxyl group is not particularly limited, and examples thereof include an epoxy group, an isocyanate group, a carbodiimide group, and the like, and an epoxy group is preferable from the viewpoint of reactivity. In particular, from the viewpoint of low contamination and low residual of unreacted materials of the crosslinking reaction due to high reactivity, glycidylamino group is preferable. That is, as the water-insoluble crosslinking agent, an epoxy crosslinking agent having an epoxy group is preferable, and a crosslinking agent having a glycidylamino group (glycidylamino crosslinking agent) is particularly preferable.

Examples of the water-insoluble crosslinking agent include glycidyl amino crosslinking agents such as 1, 3-bis (N, N-diglycidyl aminomethyl) cyclohexane (for example, manufactured by mitsubishi gas chemical Co., ltd., trade name "tetra d-C", etc.) [ 2 parts by weight or less based on 100 parts by weight of water soluble at 25 ℃), and 1, 3-bis (N, N-diglycidyl aminomethyl) benzene (for example, manufactured by mitsubishi gas chemical Co., ltd., trade name "tetra-X", etc.) [ 2 parts by weight or less based on 100 parts by weight of water soluble at 25 ℃); and (3) Tris (2, 3-epoxypropyl) isocyanurate (for example, trade name "TEPIC-G" manufactured by Nissan chemical Co., ltd.) [ 2 parts by weight or less in 100 parts by weight of water soluble at 25 ℃ and the like ]. The water-insoluble crosslinking agent may be used alone or in combination of two or more.

The emulsion resin composition may further comprise a filler. When the intermediate layer 2 is formed from the emulsion resin composition containing the filler, the transmission rate of carbon dioxide that passes through the intermediate layer 2 tends to be increased. The filler may contain an inorganic material or an organic material. Examples of the inorganic material contained in the filler include zeolite and silica. The filler is preferably hydrophilic and has high dispersibility in water, for example.

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

The filler may have fine pores. Average fineness of fillerThe pore diameter is not particularly limited, and is, for example, 0.1nm to 5nm. The density of the filler is not particularly limited, and is, for example, 0.5 to 5g/cm ³ 。

Specific examples of the filler include "zeolal" series manufactured by the superhard company of Zhongcun, and "AEROSIL" series manufactured by the AEROSIL company of japan. Examples of the "Zeoal" series manufactured by Zhongcun super hard Co., ltd include Zeoal4A 50nm and Zeoal ZSM-5. These fillers comprise zeolites. Examples of the "AEROSIL" series manufactured by AEROSIL corporation in japan include AEROSIL ox 50. The filler comprises silica. Zeoal4A 50nm and AEROSILOX50 tend to have higher hydrophilicity and higher dispersibility in water than Zeoal ZSM-5.

The concentration of the solid content in the emulsion resin composition is not particularly limited, and is, for example, 10 to 60wt%. When the emulsion resin composition contains a surfactant, the ratio of the weight of the surfactant to the weight of all solid components in the emulsion resin composition is not particularly limited, and may be, for example, 15wt% or less, 5wt% or less, or 1wt% or less. When the weight ratio of the surfactant is 15wt% or less, for example, when the emulsion resin composition is applied to the porous support 3, penetration of the emulsion resin composition into the porous support 3 can be sufficiently suppressed.

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

Viewed from another aspect, the present invention provides a separation membrane 10 comprising:

separating the functional layer 1;

a porous support 3 for supporting the separation functional layer 1; and

an intermediate layer 2 which is disposed between the separation functional layer 1 and the porous support 3 and contains a silicone polymer and a hydrophilic polymer.

The content of the silicone polymer in the intermediate layer 2 is not particularly limited, and is, for example, 10wt% or more, preferably 30wt% or more, more preferably 50wt% or more, still more preferably 70wt% or more, particularly preferably 80wt% or more, and may be 90wt% or more, and may be 95wt% or more, and may be 99wt% or more. The intermediate layer 2 may be substantially composed of a silicone-based polymer. The higher the content of the silicone polymer in the intermediate layer 2, the higher the transmission rate of the transmission 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 10wt% and may be 5wt% or less. The intermediate layer 2 may contain substantially no silicone-based polymer.

The content of the hydrophilic polymer in the intermediate layer 2 is not particularly limited, and is, for example, 1wt% or more, preferably 5wt% or more, and more preferably 10wt% or more. The higher the content of the hydrophilic polymer in the intermediate layer 2, the more the adhesion between the separation functional layer 1 and the intermediate layer 2 tends to be improved. The upper limit of the content of the hydrophilic polymer in the intermediate layer 2 is not particularly limited, but is, for example, 90wt%, preferably 70wt%, more preferably 50wt%, still more preferably 30wt%, and particularly preferably 20wt%. The content of the hydrophilic polymer in the intermediate layer 2 is preferably 10wt% to 20wt%. The intermediate layer 2 may be substantially made of a hydrophilic polymer or may not substantially contain a hydrophilic polymer, as the case may be.

The intermediate layer 2 may further contain other components than the silicone polymer and the hydrophilic polymer. Examples of the other component include a surfactant and a filler derived from the emulsion resin composition. That is, the intermediate layer 2 may contain a surfactant or a filler. For example, when the intermediate layer 2 contains a filler, the filler is embedded in a matrix containing a silicone polymer or a hydrophilic polymer, and preferably dispersed in the matrix. In the intermediate layer 2, the filler may locally aggregate.

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

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, still more preferably 10 μm or less, and particularly preferably 5 μm or less. The smaller the thickness of the intermediate layer 2, the more the decrease in the permeation rate of the permeation fluid from the separation membrane 10 tends to be suppressed. The lower limit of the thickness of the intermediate layer 2 is not particularly limited, and is, for example, 0.1 μm.

(porous support)

The porous support 3 supports the separation functional layer 1 through the intermediate layer 2. Examples of the porous support 3 include: a nonwoven fabric; porous polytetrafluoroethylene; aromatic polyamide fibers; a porous metal; sintering metal; a porous ceramic; a porous polyester; porous nylon; activating carbon fibers; a latex; an organosilicon; an organic silicon rubber; a permeable (porous) polymer comprising at least one selected from the group consisting of polyvinyl fluoride, polyvinylidene fluoride, polyurethane, polypropylene, polyethylene, polycarbonate, polysulfone, polyetheretherketone, polyacrylonitrile, polyimide, and polyphenylene oxide; a metal foam body having open cells or independent cells; polymer foam having open cells or independent cells; silicon dioxide; porous glass; screen, etc. The porous support 3 may be a combination of 2 or more of them. The porous support 3 preferably comprises polyvinylidene fluoride (PVDF).

The porous support 3 has an average pore diameter of, for example, 0.01 to 0.4. Mu.m. The thickness of the porous support 3 is not particularly limited, and 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.

(method for producing separation Membrane)

The method for manufacturing the separation membrane 10 according to the present embodiment includes, for example: coating an emulsion resin composition on the porous support 3 to form a coating film; and drying the coating film to form the intermediate layer 2. The method for preparing the emulsion resin composition is not particularly limited. As an example, the emulsion resin composition can be prepared by adding a surfactant, a filler, or the like to an emulsion containing a silicone polymer and/or a hydrophilic polymer. The emulsion may be added with a slurry containing a filler and a dispersion medium (e.g., water). When a slurry containing a filler is added to an emulsion, aggregation of the filler tends to be suppressed in the resulting emulsion resin composition. According to the emulsion resin composition in which aggregation of the filler is suppressed, occurrence of defects can be suppressed at the time of producing the intermediate layer 2. According to the method of adding the filler-containing slurry to the emulsion, the filler content in the intermediate layer 2 can also be easily increased.

The contact angle of the surface of the porous support 3 to which the emulsion resin composition is applied with water is preferably large to some extent. The surface of the porous support 3 having a large contact angle with water is suitable for preventing the emulsion resin composition containing water as a dispersion medium from penetrating into the inside of the porous support 3. The contact angle of the surface of the porous support 3 with water is, for example, 60 ° or more, and preferably 70 ° or more. The upper limit of the contact angle is not particularly limited, and is, for example, 120 °. The contact angle can be determined by JIS R3257:1999, and evaluated by the still drop method specified in 1999.

The method of applying the emulsion resin composition is not particularly limited, and for example, spin coating, dip coating, and the like can be used. The emulsion resin composition may be coated with a wire bar or the like. The coating method of the emulsion resin composition may be a method using a metal roll, for example, a gravure coating method. Drying of the coating film can be performed under heating, for example. The heating temperature of the coating film is, for example, 50 ℃ or higher. The heating time of the coating 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 by, for example, the concentration of the solid content in the emulsion resin composition, and the thickness of the coating film.

The surface of the intermediate layer 2 may be subjected to an easy-to-adhere treatment as needed. Examples of the easy-to-adhere treatment include surface treatments such as primer application, corona discharge treatment, and plasma treatment.

Next, a coating liquid containing a material of the separation functional layer 1 is prepared. A coating solution containing a material of the separation functional layer 1 is coated on the intermediate layer 2 to obtain a coating film. The separation functional layer 1 can be formed by drying the coating film. It is preferable that the contact angle of the surface of the intermediate layer 2 to be coated with the coating liquid with water is small to some extent. The surface of the intermediate layer 2 having 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 water is, for example, 120 ° or less, preferably 110 ° or less. The lower limit of the contact angle is not particularly limited, and is, for example, 70 °. The contact angle can be determined by JIS R3257:1999, and evaluated by the still drop method specified in 1999.

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

The peel force P1 can be measured by the following method. First, a laminate of the intermediate layer 2 and the porous support 3 to be evaluated was cut into test pieces 25mm wide by 100mm long. Next, a single-sided pressure-sensitive adhesive tape (No. 7235, 18mm in width, manufactured by Ridong electric company) was bonded to the intermediate layer 2 provided on the test piece, and a 2kg roller was reciprocated once to press the two layers. Subsequently, the intermediate layer 2 was peeled from the porous support 3 together with the single-sided adhesive tape at a peeling angle of 90℃and a peeling speed of 300mm/min using a commercially available tensile tester. The peeling force at this time was determined as peeling force P1. The above measurement was performed in an atmosphere at 23 ℃.

The method for applying the coating liquid and the drying conditions may be the methods and conditions described above for the intermediate layer 2. The coating liquid containing the material of the separation functional layer 1 may be applied by spin coating. By forming the separation functional layer 1 on the intermediate layer 2, the separation membrane 10 can be obtained.

(Property of separation Membrane)

As described above, in the separation membrane 10 of the present embodiment, the intermediate layer 2 is formed of the emulsion resin composition. According to the study of the present inventors, even when the emulsion resin composition is applied to the porous support 3, the polymer contained in the emulsion resin composition is less likely to penetrate into the porous support 3. In particular, in the case where the emulsion resin composition contains water as a dispersion medium and the contact angle of the surface of the porous support 3 with water is large, penetration of the polymer into the inside of the porous support 3 is significantly suppressed. Since the penetration of the polymer into the porous support 3 is suppressed, the occurrence of defects such as pinholes and the like and the variation in thickness in the formed intermediate layer 2 are suppressed. For example, according to the emulsion resin composition, the intermediate layer 2 having a small thickness can be easily produced while suppressing the variation in thickness. In the present embodiment, by forming the separation functional layer 1 on the intermediate layer 2 formed of the emulsion resin composition, variation in separation performance of the separation membrane 10 tends to be suppressed.

The separation membrane 10 can preferentially permeate, for example, an acid gas contained in the mixed gas. As an example, the transmission rate T1 of carbon dioxide transmitted through the separation membrane 10 is, for example, 10GPU or more, preferably 50GPU or more, and more preferably 100GPU or more. The upper limit value of the transmission speed T1 is not particularly limited, and is, for example, 500GPU. It should be noted that GPU refers to 10 ^-6 ·cm ³ (STP)/(sec·cm ² ·cmHg)。cm ³ (STP) refers to the volume of carbon dioxide at 1 atmosphere and 0 ℃.

The transmission rate T1 can be calculated by the following method. First, a mixed gas containing carbon dioxide and nitrogen is supplied to a space adjacent to one surface 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 surface of the separation membrane 10 (for example, the main surface 12 on the porous support side of the separation membrane 10) is depressurized. Thus, a permeate having permeated through the separation membrane 10 is obtained. The weight of the passing fluid, and the volume ratio of carbon dioxide and the volume ratio of nitrogen in the passing fluid were measured. From the measurement result, the transmission rate T1 can be calculated. In the above operation, the concentration of carbon dioxide in the mixed gas was 50vol% in the standard state (0 ℃ C., 101 kPa). The temperature of the mixed gas supplied to the space adjacent to one surface of the separation membrane 10 was 30℃and the pressure was 0.1MPa. The space adjacent to the other surface of the separation membrane 10 is depressurized so that the pressure in the space becomes 0.1MPa smaller than the atmospheric pressure in the measurement environment.

Under the above-described conditions for measuring the permeation rate T1, the separation coefficient α1 of carbon dioxide with respect to nitrogen in the separation membrane 10 is not particularly limited, and is, for example, 20 or more, preferably 40 or more. The upper limit value of the separation coefficient α1 is not particularly limited, and is, for example, 100. The separation coefficient α1 can be calculated according to the following equation. Wherein, in the following formula, X _A X is X _B The volume ratio of carbon dioxide and the volume ratio of nitrogen in the mixed gas are respectively. Y is Y _A Y and Y _B The volume ratio of carbon dioxide and the volume ratio of nitrogen in the permeate fluid having permeated the separation membrane 10 are respectively.

Separation coefficient α1= (Y) _A /Y _B )/(X _A /X _B )

As described above, in the separation membrane 10 of the present embodiment, the variation in separation performance is suppressed. In detail, in the present embodiment, the coefficient of variation of the permeation rate T1 of carbon dioxide through the separation membrane 10 and the coefficient of variation of the separation coefficient α1 of carbon dioxide through the separation membrane 10 with respect to nitrogen tend to be small. As an example, the coefficient of variation of the permeation rate T1 of carbon dioxide through the separation membrane 10 is, for example, less than 0.18, preferably less than 0.15, more preferably less than 0.10, and even more preferably less than 0.05. The lower limit value of the coefficient of variation of the transmission rate T1 is not particularly limited, and is, for example, 0.001. The coefficient of variation of the transmission rate T1 can be determined by the following method. First, the separation membrane 10 was cut, and at least 3 test pieces were prepared. The carbon dioxide permeation rate T1 was measured for each test piece by the method described above. The average value and standard deviation of the obtained transmission rate T1 were calculated. The ratio of the standard deviation to the average value can be regarded as a variation coefficient of the transmission rate T1.

The coefficient of variation of the carbon dioxide separation coefficient α1 of the separation membrane 10 with respect to nitrogen is, for example, 0.50 or less, preferably 0.40 or less, more preferably 0.30 or less, still more preferably 0.20 or less, and particularly preferably 0.10 or less. The lower limit value of the variation coefficient of the separation coefficient α1 is not particularly limited, and is, for example, 0.001. The variation coefficient of the separation coefficient α1 can be determined by the following method. First, the separation membrane 10 was cut, and at least 3 test pieces were prepared. The separation coefficient α1 was measured for each test piece by the method described above. The average value and standard deviation of the obtained separation coefficient α1 were calculated. The ratio of the standard deviation to the average value can be regarded as a variation coefficient of the separation coefficient α1.

The transmission rate T2 of the carbon dioxide passing through the intermediate layer 2 is, for example, 10GPU or more, preferably 500GPU or more, more preferably 1000GPU or more, further preferably 1100GPU or more, particularly preferably 1500GPU or more, particularly preferably 2000GPU or more, and may be 3000GPU or more. The upper limit value of the transmission speed T2 is not particularly limited, and is 10000GPU, for example. The transmission rate T2 may be measured by the same method as the transmission rate T1, except that the laminated body of the intermediate layer 2 and the porous support 3 is used instead of the separation membrane 10.

Under the above-described measurement conditions of the permeation rate T2, the separation coefficient α2 of carbon dioxide from nitrogen in the intermediate layer 2 is not particularly limited, and is, for example, 1 or more, preferably 5 or more. The upper limit value of the separation coefficient α2 is not particularly limited, and is, for example, 20. The separation coefficient α2 can be calculated by the same method as the separation coefficient α1.

The degree of the deviation of the separation performance of the separation membrane 10 can be predicted from the degree of the deviation of 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 the variation in the separation performance of the separation membrane 10 tends to be suppressed. The coefficient of variation of the transmission rate T2 of carbon dioxide through the intermediate layer 2 is, for example, 0.50 or less, preferably 0.40 or less, more preferably 0.30 or less, still more preferably 0.20 or less, and particularly preferably 0.15 or less. The lower limit value of the coefficient of variation of the transmission 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 the laminated body of the intermediate layer 2 and the porous support 3 is used instead of the separation membrane 10.

The coefficient of variation of the separation coefficient α2 of carbon dioxide from 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 still more preferably 0.10 or less. The lower limit value of the variation coefficient of the separation coefficient α2 is not particularly limited, and is, for example, 0.001. The variation coefficient of the separation coefficient α2 can be determined by the same method as that of the separation coefficient α1, except that the laminated body of the intermediate layer 2 and the porous support 3 is used instead of the separation membrane 10.

In the separation membrane 10 of the present embodiment, the separation force P2 of the separation functional layer 1 with respect to the intermediate layer 2 is not particularly limited, and is, for example, 0.4N/10mm or more, preferably 1.0N/10mm or more, more preferably 2.0N/10mm or more, still more preferably 3.0N/10mm or more, and particularly preferably 4.0N/10mm or more. The greater the peeling force P2, the more the separation functional layer 1 tends to be inhibited from peeling from the intermediate layer 2 at the time of use of the separation film 10 or the like. The upper limit of the peeling force P2 is not particularly limited, and is, for example, 10.0N/10mm. The release force P2 of the separation functional layer 1 with respect to the intermediate layer 2 can be adjusted by, for example, the type and content of the hydrophilic polymer contained in the intermediate layer 2.

The peel force P2 can be measured by the following method. First, the separation membrane 10 to be evaluated was cut into test pieces 10mm wide by 50mm long. Subsequently, the whole surface of the separation functional layer 1 provided in the test piece was laminated with a film made of polyethylene terephthalate via a double-sided adhesive tape (No. 500 manufactured by the eastern electric company), and a 2kg roller was reciprocated once, and these were pressure-bonded. Subsequently, the separation functional layer 1 was peeled from the intermediate layer 2 together with the film at a peeling angle of 90℃and a peeling speed of 300mm/min using a commercially available tensile tester. The peeling force at this time is specified as the peeling force P2. The above measurement was performed in an atmosphere at 23 ℃. The double-sided adhesive tape (No. 500) used in the measurement of the peeling force P2 was a tape having a larger adhesive force than the single-sided adhesive tape (No. 7235) used in the measurement of the peeling force P1.

As the use of the separation membrane 10 of the present embodiment, there is a use for separating an acid gas from a mixed gas containing the acid gas. Examples of the acid gas of the mixed gas include carbon dioxide, hydrogen sulfide, carbonyl sulfide, and sulfur oxide (SO _x ) Hydrogen cyanide and Nitrogen Oxides (NO) _x ) And the like, carbon dioxide is preferable. The mixed gas contains other gases than the acid gas. Examples of the other gas include nonpolar gases such as hydrogen and nitrogen, and inert gases such as helium, and nitrogen is preferable. The separation membrane 10 of the present embodiment is particularly suitable for use in separating carbon dioxide from a mixed gas containing carbon dioxide and nitrogen. However, the use of the separation membrane 10 is not limited to the use of separating an acid gas from the above-described mixed gas.

Embodiment of Membrane separation device

As shown in fig. 2, the membrane separation device 100 of the present embodiment includes a separation membrane 10 and a tank 20. The tank 20 includes a 1 st chamber 21 and a 2 nd chamber 22. The separation membrane 10 is disposed inside the tank 20. Inside the tank 20, the separation membrane 10 separates the 1 st chamber 21 from the 2 nd chamber 22. The separation membrane 10 extends from one of the 1 pair of wall surfaces of the tank 20 to the other.

The 1 st chamber 21 has an inlet 21a and an outlet 21b. Chamber 2 has an outlet 22a. The inlet 21a, the outlet 21b, and the outlet 22a are openings formed in the wall surface of the tank 20, for example.

The membrane separation using the membrane separation device 100 is performed, for example, by the following method. First, the mixed gas 30 containing the acid gas is supplied to the 1 st chamber 21 through the inlet 21 a. The concentration of the acid gas in the mixed gas 30 is not particularly limited, and is, for example, 0.01vol% (100 ppm) or more, preferably 1vol% or more, more preferably 10vol% or more, still more preferably 30vol% or more, and particularly preferably 50vol% or more in a standard state. The upper limit value of the concentration of the acid gas in the mixed gas 30 is not particularly limited, and is, for example, 90vol% in a standard state.

The pressure in the 1 st chamber 21 can be increased by supplying the mixed gas 30. The membrane separation device 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 1 st chamber 21 is, for example, 0.1MPa or more, and preferably 0.3MPa or more.

The pressure in the 2 nd chamber 22 can be reduced while the mixed gas 30 is supplied to the 1 st chamber 21. The membrane separation device 100 may further include a pump (not shown) for depressurizing the inside of the 2 nd chamber 22. The 2 nd chamber 22 may be depressurized so that the space in the 2 nd chamber 22 is smaller than the atmospheric pressure in the measurement environment by, for example, 10kPa or more, preferably 50kPa or more, more preferably 100kPa or more.

By supplying the mixed gas 30 into the 1 st chamber 21, the permeate 35 having a higher acid gas content than the mixed gas 30 can be obtained on the other surface side of the separation membrane 10. I.e. to the 2 nd chamber 22 through fluid 35. The permeate fluid 35 contains, for example, an acid gas as a main component. However, the permeate fluid 35 may contain a small amount of a gas other than the acidic gas. The permeate fluid 35 is discharged to the outside of the tank 20 via the outlet 22 a.

The concentration of the acid gas in the mixed gas 30 gradually decreases from the inlet 21a toward the outlet 21b of the 1 st chamber 21. The mixed gas 30 (the non-permeate fluid 36) treated in the 1 st chamber 21 is discharged to the outside of the tank 20 through the outlet 21 b.

The membrane separation device 100 of the present embodiment is suitable for a flow-through (continuous) membrane separation method. However, the membrane separation device 100 of the present embodiment may be used in a batch membrane separation method.

Modification of Membrane separation device

As shown in fig. 3, the membrane separation device 110 of the present embodiment includes a center tube 41 and a laminate 42. The laminate 42 includes the separation membrane 10. The membrane separation device 110 is a spiral membrane element.

The center tube 41 has a cylindrical shape. A plurality of holes for allowing the fluid 35 to flow into the center tube 41 are formed in the surface of the center tube 41. Examples of the material of 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.

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

As the supply-side channel material 43 and the transmission-side channel material 44, for example, a resin mesh made of polyphenylene sulfide (PPS) or ethylene-chlorotrifluoroethylene copolymer (ECTFE) may be used.

The membrane separation using the membrane separation device 110 is performed, for example, by the following method. First, the mixed gas 30 is supplied to one end of the wound laminate 42. The permeate fluid 35 having permeated the separation membrane 10 of the laminate 42 moves into the center tube 41. The permeate fluid 35 is discharged to the outside via the center tube 41. The mixed gas 30 (the non-permeate fluid 36) treated in the membrane separation device 110 is discharged to the outside from the other end of the wound laminate 42. Thereby, the acid gas can be separated from the mixed gas 30.

Examples

The present invention will be described in further detail with reference to examples and comparative examples, but the present invention is not limited thereto.

Example 1

First, 1.6g of an aqueous emulsion containing a silicone polymer (POLON-MF-56 manufactured by Xinyue chemical industry), 0.2g of an aqueous emulsion containing a urethane polymer as a hydrophilic polymer (NeoRez R-2170 manufactured by DSM Coating Resins Co.) and 33.3g of ion-exchanged water for dilution were mixed to prepare 35.0g of an emulsion resin composition having a solid content concentration of 2 wt%. Then, the prepared emulsion resin composition was applied to a porous support using an applicator (gap: 50 μm), thereby obtaining a coating film. As the porous support, UF membrane (ultrafiltration membrane) RS-50 (laminate of PVDF porous layer and PET nonwoven fabric) manufactured by Nitto electric company was used. The coating film was formed on the PVDF porous layer of RS-50. The obtained coating film was dried at 130℃for 10 minutes, thereby forming an intermediate layer having a thickness of 1. Mu.m. In the intermediate layer, the content of the silicone polymer was 90 parts by weight, and the content of the urethane polymer was 10 parts by weight.

Subsequently, 0.7g of a polyether block amide resin (Pebax MH1657 manufactured by armema corporation) was put into a mixed solution of 24.0g of isopropyl alcohol and 10.3g of water, and stirred at 80 ℃ for 3 hours, whereby 35.0g of a coating liquid containing the polyether block amide resin at a concentration of 2wt% was prepared. The coating liquid contained 0.01g of a leveling agent (KP-112 manufactured by Xinyue chemical industry). The prepared coating liquid was applied to the intermediate layer using an applicator (gap: 50 μm), thereby obtaining a coating film. Subsequently, the obtained coating film was dried in an oven at 60 ℃ for 30 minutes, thereby forming a separation functional layer. Thus, a separation membrane of example 1 was obtained.

Examples 2 to 22

Separation membranes of examples 2 to 22 were obtained in the same manner as in example 1, except that the type of hydrophilic polymer and the content of the polymer in the intermediate layer were changed as shown in tables 1 to 2.

Example 23

A separation film of example 23 was obtained in the same manner 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 subjected to corona treatment before forming the separation functional layer.

Reference example 1

A laminate of reference example 1 was obtained in the same manner as in example 23, except that the surface of the intermediate layer was not subjected to corona treatment and a separation functional layer was not formed.

Comparative example 1

A separation membrane of comparative example 1 was obtained in the same manner as in example 23 except that a solution containing a silicone polymer (YSR-3022 manufactured by Momentive Performance Materials company) 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 contains a curing catalyst and a curing retarder, and the curing reaction of the silicone polymer is performed at the time of producing the intermediate layer.

Reference example 2

A laminate of reference example 2 was obtained in the same manner as in comparative example 1 except that the surface of the intermediate layer was not subjected to corona treatment and a separation functional layer was not formed.

Example 24

First, 0.7g of an aqueous emulsion (POLON-MF-56 manufactured by Xinyue chemical industry), 1.2g of an aqueous slurry containing a filler, and 18.1g of ion-exchanged water for dilution were mixed to prepare 20.0g of an emulsion resin composition having a solid content concentration of 2 wt%. As the aqueous slurry containing the filler, an aqueous slurry of zeolite (Zeoal 4a 50nm aqueous slurry manufactured by the super hard company of the middle village) was used. Then, the prepared emulsion resin composition was applied to a porous support using an applicator (gap: 100 μm), thereby obtaining a coating film. As the porous support, UF membrane (ultrafiltration membrane) RS-50 (laminate of PVDF porous layer and PET nonwoven fabric) manufactured by Nitto electric company was used. The coating film was formed on the PVDF porous layer of RS-50. The obtained coating film was dried at 130℃for 10 minutes, thereby forming an intermediate layer having a thickness of 2. Mu.m. 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.

Subsequently, 0.7g of a polyether block amide resin (Pebax MH1657 manufactured by armema corporation) was put into a mixed solution of 24.0g of isopropyl alcohol and 10.3g of water, and stirred at 80 ℃ for 3 hours, whereby 35.0g of a coating liquid containing the polyether block amide resin at a concentration of 2wt% was prepared. The coating liquid contained 0.01g of a leveling agent (KP-112 manufactured by Xinyue chemical industry). The prepared coating liquid was applied to the intermediate layer using an applicator (gap: 50 μm), thereby obtaining a coating film. Subsequently, the obtained coating film was dried in an oven at 60 ℃ for 30 minutes, thereby forming a separation functional layer. Thus, a separation membrane of example 24 was obtained.

Examples 25 to 26

Separation membranes of examples 25 to 26 were obtained in the same manner as in example 24, except that the types of fillers, and the contents of the polymer and the fillers in the intermediate layer were changed as shown in table 4.

Example 27

First, water was added to the surfactant and diluted 100 times. BYK-347 manufactured by BYK-Chemie Japan was used as the surfactant. Next, 800g of the obtained diluted solution, 400g of an aqueous emulsion (POLON-MF-56 manufactured by Xinyue chemical industry) containing a silicone polymer, and 900g of ion-exchanged water for dilution were mixed to prepare 2100g of an emulsion resin composition having a solid content of 8 wt%. Next, the prepared emulsion resin composition was applied to a porous support using a gravure coater (gap: 5 μm), thereby obtaining a coating film. In the case of using a gravure coater, it is necessary to make the emulsion resin composition compatible with the metal roll in advance. In example 27, although the concentration of the solid content in the emulsion resin composition was a low value of 8wt%, shrinkage cavity of the emulsion resin composition on the metal roll was not confirmed. The thickness of the coating film (coating thickness) was 5. Mu.m. As the porous support, UF membrane (ultrafiltration membrane) RS-50 (laminate of PVDF porous layer and PET nonwoven fabric) manufactured by Nitto electric company was used. The coating film was formed on the PVDF porous layer of RS-50. The obtained coating film was dried at 130℃for 2.5 minutes, thereby forming an intermediate layer having a thickness of 0.5. Mu.m. In the intermediate layer, the content of the silicone polymer was 100 parts by weight, and the content of the surfactant was 5 parts by weight.

Subsequently, 30g of polyether block amide resin (Pebax MH1657 manufactured by armema corporation) was put into a mixed solution of 129g of isopropyl alcohol and 441g of water, and stirred at 80 ℃ for 3 hours, thereby preparing 1500g of a coating liquid containing polyether block amide resin at a concentration of 2 wt%. The coating liquid contained 0.3g of a leveling agent (KP-112 manufactured by Xinyue chemical industry). The prepared coating liquid was applied to the intermediate layer using an applicator (gap: 50 μm), thereby obtaining a coating film. Subsequently, the obtained coating film was dried in an oven at 80 ℃ for 2.5 minutes, thereby forming a separation functional layer. Thus, a separation membrane of example 27 was obtained.

Reference example 3

A laminate of reference example 3 was obtained in the same manner as in example 23, except that the gap of the applicator at the time of forming the intermediate layer was set to 100 μm, the surface of the intermediate layer was not subjected to corona treatment, and a separation functional layer was not formed.

[ evaluation of separation Performance of intermediate layer ]

The separation performance of the intermediate layer was evaluated by the following method for examples, comparative examples and reference examples. First, the laminate of the intermediate layer and the porous support obtained in the stage before the formation of the separation functional layer was cut, and 3 test pieces were prepared. For each test piece, the separation coefficient α2 (CO ₂ /N ₂ ) And a carbon dioxide permeation rate T2. In detail, the test piece was set in a metal cell, and sealed with an O-ring so that no leakage occurred. Then, the mixed gas was injected into the metal cell so that the mixed gas contacted the main surface of the test piece on the intermediate layer side. The mixed gas is substantially composed of carbon dioxide and nitrogen. The concentration of carbon dioxide in the mixed gas was 50vol% in the standard state. The temperature of the mixed gas injected into the metal cell was 30℃and the pressure was 0.1MPa. Next, the space in the metal cell adjacent to the main surface on the porous support side of the test piece was depressurized by a vacuum pump. At this time, the space was depressurized to a pressure of 0.1MPa lower than the atmospheric pressure in the measurement environment. Thus, a permeate was obtained. Based on the composition of the obtained permeate fluid, the weight of the permeate fluid, and the like, the separation coefficient α2 of the test piece and the permeation rate T2 of carbon dioxide were calculated. Further, the variation coefficient of the separation coefficient α2 and the variation coefficient of the transmission rate T2 are determined based on the separation coefficient α2 and the transmission rate T2 of all the test pieces. In examples 1 to 27 and reference examples 1 and 3, the coefficient of variation of the separation coefficient α2 of the intermediate layer and the coefficient of variation of the transmission rate T2 were each 0.20 or less. On the other hand, in comparative example 1 and reference example 2, the coefficient of variation of the separation coefficient α2 of the intermediate layer and the coefficient of variation of the transmission rate T2 both greatly exceeded 0.20 and were 0.50 or more. The average value of the obtained separation coefficient α2 and the average value of the transmission rate T2 are shown in tables 1 to 4.

[ evaluation of separation Performance of separation Membrane ]

With respect to examples 1, 4, 24 to 27 and comparative example 1, the separation performance of the separation membrane was also evaluated. The separation performance of the separation membrane was evaluated by the same method as that of the intermediate layer, except that the separation membrane was used instead of the laminate of the intermediate layer and the porous support. Thus, the separation coefficient α1 (CO ₂ /N ₂ ) And a carbon dioxide permeation rate T1. In table 5, the average value and the variation coefficient are shown for the obtained separation coefficient α1 and the transmission rate T1. Table 5 also shows the average value and the variation coefficient of the separation coefficient α2 and the transmission rate T2 of the intermediate layer in examples 1, 4, 24 to 27, comparative example 1 and reference example 2.

[ contact Angle with Water ]

Regarding examples 1 to 23, comparative example 1 and reference examples 1 to 2, the contact angle of the surface of the intermediate layer with water was measured by the above-described method. In the measurement, a laminate of an intermediate layer and a porous support obtained in a stage before the formation of the separation functional layer was used. The results are shown in tables 1 to 3.

[ peeling force P1 of the intermediate layer against the porous support ]

The peeling force P1 of the intermediate layer against the porous support was measured by the method described above for examples 1 to 23, comparative example 1 and reference examples 1 to 2. In the measurement, a laminate of an intermediate layer and a porous support obtained in a stage before the formation of the separation functional layer was used. The results are shown in tables 1 to 3.

[ Release force P2 of separation functional layer against intermediate layer ]

The separation force P2 of the separation functional layer with respect to the intermediate layer was measured by the above-described method for the separation membranes of examples 1 to 23 and comparative example 1. The results are shown in tables 1 to 3.

[ observation of defects of intermediate layer and separation functional layer ]

With comparative example 1, the surface of the intermediate layer was observed with an electron microscope at a stage before the formation of the separation functional layer. The results are shown in FIG. 4A. As can be seen from fig. 4A, in comparative example 1, defects (pinholes) were generated on the surface of the intermediate layer.

Further, a dye solution was applied to the separation functional layer of the separation membrane of comparative example 1. At this time, the dyeing liquid permeates into the separation functional layer at the portion where the defect (pinhole) exists, and the portion of the separation functional layer is dyed. The results are shown in FIG. 4B. As can be seen from fig. 4B, in comparative example 1, a defect was also generated in the separation functional layer by forming the separation functional layer on the intermediate layer having the defect.

TABLE 1

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TABLE 2

TABLE 3

TABLE 4

TABLE 5

The abbreviations in tables 1 to 4 are as follows.

MF-56: POLON-MF-56 from Xinyue chemical industry

YSR-3022: YSR-3022 manufactured by Momentive Performance Materials Co

R-2170: neoRez R-2170 manufactured by DSM Coating Resins Co

DA200: aracoat DA200 manufactured by the chemical industry Co., ltd

SF470: superflex 470, manufactured by first Industrial pharmaceutical Co

WLS213: hydron WLS213 manufactured by DIC Co

SF420: superflex 420 manufactured by first Industrial pharmaceutical Co

AP4690N: polysol AP4690N manufactured by Showa electric company

WHW-822: CERANATE WHW-822 manufactured by DIC Co

KT-8803: elitel KT-8803 manufactured by Unitika Co

EVA P-3N: polysol EVA P-3N manufactured by Showa electric company

4A: zeoal 4A 50nm aqueous slurry (solid content concentration 10wt%, average particle diameter 50nm, average pore diameter 0.4nm, density about 2 g/cm) manufactured by Zhongcun super hard Co ³ )

ZSM-5: zeoal ZSM-5 aqueous slurry (solid content concentration 30wt%, average particle diameter 100nm, average pore diameter 0.54-0.56 nm, density about 2 g/cm) manufactured by Zhongcun super hard Co ³ )

AEROSILOX50: AEROSILOX50 manufactured by AEROSIL Co., ltd

BYK-349: BYK-349 made by BYK-Chemie Japan company

As described above, in examples 1 to 27, the coefficient of variation of the separation coefficient α2 and the coefficient of variation of the transmission rate T2 of the intermediate layer were each smaller than that of comparative example 1 and were each 0.20 or less. As is clear from table 5, in examples 1, 4, and 24 to 27 in which the variation in separation performance of the intermediate layer was suppressed, the variation coefficient of the separation coefficient α1 of the separation membrane and the variation coefficient of the transmission rate T1 were also smaller than those of comparative example 1. From the results of table 5, it is estimated that the variation in separation performance of the separation membrane of other examples is also suppressed as compared with comparative example 1. It is apparent from examples 24 to 26 that the intermediate layer containing the filler tends to have a higher carbon dioxide permeation rate T2 than that of reference example 3.

Industrial applicability

The separation membrane of the present embodiment is suitable for separating an acid gas from a mixed gas containing the acid gas. In particular, the separation membrane of the present embodiment is suitable for separating carbon dioxide from waste gas of a chemical plant or a thermal power generation.

Claims

1. A separation membrane comprising:

separating the functional layer;

a porous support for supporting the separation functional layer; and

and an intermediate layer which is disposed between the separation functional layer and the porous support and is formed of an emulsion resin composition.

2. The separation membrane of claim 1, wherein the intermediate layer comprises a silicone-based polymer.

3. A separation membrane according to claim 1 or 2, wherein the intermediate layer comprises a hydrophilic polymer.

4. The separation membrane according to claim 3, wherein the hydrophilic polymer comprises at least one selected from the group consisting of urethane-based polymers, (meth) acrylic urethane-based polymers, ester-based polymers, and vinyl ester-based polymers.

5. The separation membrane according to claim 3 or 4, wherein the content of the hydrophilic polymer in the intermediate layer is 10wt% to 20wt%.

6. The separation membrane according to any one of claims 1 to 5, wherein the emulsion resin composition comprises water as a dispersion medium.

7. The separation membrane according to any one of claims 1 to 6, wherein the emulsion resin composition comprises a surfactant.

8. The separation membrane according to claim 7, wherein the ratio of the weight of the surfactant to the weight of all solid components in the emulsion resin composition is 15wt% or less.

9. The separation membrane of any one of claims 1 to 8, wherein the intermediate layer comprises a filler.

10. The separation membrane of claim 9, wherein the filler has a particle shape and an average particle diameter less than a thickness of the intermediate layer.

11. The separation membrane of any one of claims 1 to 10, wherein the separation functional layer comprises a polyether block amide resin.

12. The separation membrane of any one of claims 1 to 11, wherein the porous support comprises polyvinylidene fluoride.

13. The separation membrane according to any one of claims 1 to 12, wherein the thickness of the intermediate layer is 10 μm or less.

14. The separation membrane according to any one of claims 1 to 13, wherein the separation functional layer has a peel force of 3.0N/10mm or more with respect to the intermediate layer.

15. The separation membrane according to any one of claims 1 to 14, for separating carbon dioxide from a mixed gas comprising carbon dioxide and nitrogen.

16. A method for producing a separation membrane comprising a separation functional layer, a porous support for supporting the separation functional layer, and an intermediate layer disposed between the separation functional layer and the porous support,

the manufacturing method comprises the following steps:

and drying the coating film to form the intermediate layer.

17. A separation membrane comprising:

separating the functional layer;

a porous support for supporting the separation functional layer; and

an intermediate layer which is disposed between the separation functional layer and the porous support and contains an organosilicon polymer and a hydrophilic polymer.