WO2016121280A1 - Composite anion exchange membrane, method for producing same, ion exchange membrane module, and ion exchanger - Google Patents

Abstract

Provided are: a composite anion exchange membrane which has excellent monovalent ion selectivity; a method for producing this composite anion exchange membrane; and an ion exchange membrane module and an ion exchanger, each of which uses this composite anion exchange membrane. This composite anion exchange membrane comprises a surface layer having anionic functional groups on one surface or both surfaces of an anion exchange membrane that serves as a base. The density of the anionic functional groups in the surface layer is from 3.0 equivalent/g to 10.0 equivalent/g.

Description

Composite anion exchange membrane and method for producing the same, ion exchange membrane module, and ion exchange device

The present invention relates to a composite anion exchange membrane and a method for producing the same, an ion exchange membrane module, and an ion exchange device.

The ion exchange membrane is used for electrodeionization (EDI), continuous electrodeionization (CEDI), electrodialysis (ED), reverse electrodialysis (EDR), and the like.
Electrodesalting (EDI) is a water treatment process in which ions are removed from an aqueous liquid using ion exchange membranes and electrical potentials to achieve ion transport. Unlike other water purification techniques such as conventional ion exchange, it does not require the use of chemicals such as acid or caustic soda and can be used to produce ultrapure water. Electrodialysis (ED) and reverse electrodialysis (EDR) are electrochemical separation processes that remove ions and the like from water and other fluids.

Recently, an increase in nitrate ion concentration in groundwater has become a problem on a global scale, and a method for removing nitrate ion by electrodialysis using an ion exchange membrane has attracted attention. In electrodialysis, during long-term driving, it is known that precipitation (scaling) of sparingly soluble salts due to divalent sulfate ions and the like occurs and efficiency is lowered. In general, ion exchange membranes have the property of selectively permeating only cations or anions, but in addition to this selectivity, while eliminating divalent anions such as sulfate ions that can cause scaling, monovalent It is important to selectively permeate only nitrate ions and remove them efficiently. Therefore, development of a technique for selectively transmitting only monovalent ions has been actively performed (for example, see Patent Document 1).

In Patent Document 1, when removing nitrate ions from an aqueous solution containing nitrate ions by electrodialysis, a membrane having a negative charge thin layer having a thickness of 10 angstroms to 5 μm on the membrane surface is used as the anion exchange membrane. A method for removing nitrate ions is described, wherein the anion exchange membrane is arranged with the side having the thin layer as the desalting chamber side.

JP-A-7-265863

The problem to be solved by the present invention is a composite anion exchange membrane excellent in monovalent ion selectivity, a production method thereof, an ion exchange membrane module using the composite anion exchange membrane, and an ion exchange device Is to provide.

The above-described problems of the present invention have been solved by means described in the following <1>, <6>, <8> or <9>. It is described below together with <2> to <5> and <7> which are preferred embodiments.
<1> A surface layer having an anionic functional group is provided on one side or both sides of a base anion exchange membrane, and the density of the anionic functional group in the surface layer is 3.0 eq / g to 10.0 eq / a composite anion exchange membrane characterized in that
<2> The composite anion exchange membrane according to <1>, wherein the surface layer and the base anion exchange membrane are bonded via a covalent bond,
<3> The composite anion exchange membrane according to <1> or <2>, wherein the anionic functional group is a sulfo group, a carboxy group, or a phosphate group,
<4> The composite anion exchange membrane according to any one of <1> to <3>, wherein the surface layer has a structure of the following formula 1.

In Formula 1, each R ¹ independently represents an anionic functional group, i represents an integer of 1 to 5, L ¹ represents an i + m-valent linking group, and * represents each independently anion exchange serving as a base Represents a bonding position with a film or a surface layer material, j represents an integer of 1 to 3, R ² independently represents a monovalent organic group, k represents an integer of (3-j), When a plurality of R ¹ and R ² are present, they may be the same as or different from each other, and m represents an integer of 1 to 6,
<5> The composite anion exchange membrane according to any one of <2> to <4>, wherein the base anion exchange membrane has a hydroxy group,
<6> An application step of applying a coating solution for forming a surface layer containing a silane coupling agent having an anionic functional group on one side or both sides of the base anion exchange membrane, and the applied coating for forming the surface layer A method for producing a composite anion exchange membrane, comprising a drying step of drying the liquid;
<7> The method for producing a composite anion exchange membrane according to <6>, further including a plasma treatment step of performing plasma treatment on the base anion exchange membrane before the coating step,
<8> An ion exchange membrane module comprising the composite anion exchange membrane according to any one of <1> to <5>,
<9> An ion exchange device comprising the composite anion exchange membrane according to any one of <1> to <5>.

According to the present invention, there are provided a composite anion exchange membrane excellent in monovalent ion selectivity, a production method thereof, an ion exchange membrane module using the composite anion exchange membrane, and an ion exchange device. I was able to.

It is a schematic sectional drawing which shows an example of the composite anion exchange membrane of this invention. It is the schematic which shows an example of the ion exchange apparatus using the composite anion exchange membrane of this invention. It is the schematic which shows an example of the ion exchange apparatus used at the time of evaluation of the time-dependent change of the selectivity of the composite anion exchange membrane of this invention.

Hereinafter, the contents of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
In the notation of groups (atomic groups) in this specification, the notation that does not indicate substitution and non-substitution includes not only those having no substituent but also those having a substituent. For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
Furthermore, the geometrical isomer that is the substitution pattern of the double bond in each formula may be either E-form or Z-form, unless otherwise specified, even if one of the isomers is described for the convenience of display. Or a mixture thereof.
In addition, the chemical structural formula in this specification may be expressed as a simplified structural formula in which a hydrogen atom is omitted.
In this specification, “(meth) acrylate” represents acrylate and methacrylate, “(meth) acryl” represents acryl and methacryl, “(meth) acryloyl” represents acryloyl and methacryloyl, “(meth) ) Acrylamide "refers to acrylamide and methacrylamide.
In the present invention, “mass%” and “wt%” are synonymous, and “part by mass” and “part by weight” are synonymous.
Moreover, in this invention, the combination of a preferable aspect is a more preferable aspect.

(Composite anion exchange membrane)
The composite anion exchange membrane of the present invention has a surface layer having an anionic functional group on one side or both sides of a base anion exchange membrane (hereinafter also referred to as “base membrane”), and an anionic property in the surface layer. The density of the functional group is 3.0 equivalent / g to 10.0 equivalent / g.
The composite anion exchange membrane of the present invention preferably has a surface layer having an anionic functional group on both sides.

In an anion exchange membrane having a conventional anionic surface layer, the distance between the anionic functional groups in the surface layer is relatively long, and there is a region that is less susceptible to repulsive force due to Coulomb force when the anion in the treated water permeates. It was. In this region, various anions are considered to be able to permeate relatively freely, which is considered to be one of the causes of a decrease in monovalent ion selectivity of the membrane. In the present invention, by disposing anionic functional groups at a higher density on the surface of the anion exchange membrane, the distance between the anionic functional groups is reduced, the area where the influence of Coulomb force is small is reduced, and monovalent ion selectivity is reduced. It is thought that it was possible to improve. Even if the density of the anionic functional group is low, the area where the influence of Coulomb force is small can be reduced by increasing the film thickness and lengthening the permeation path. The problem that a rate deteriorates arises and it is not preferable. The present inventors have found that according to the configuration of the present invention, the transport number is maintained while monovalent ion selectivity is obtained.
In addition, in the present invention, an excellent effect of reducing the water permeability was also confirmed. This is considered to be caused by the fact that the surface layer is densely formed.

The composite anion exchange membrane of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals indicate the same symmetry.
FIG. 1 is a schematic cross-sectional view showing an example of the composite anion exchange membrane of the present invention.
In FIG. 1, an anion exchange membrane 1 serving as a base has surface layers 2 on both sides. The anion exchange membrane 1 serving as a base preferably has the surface layer 2 on both sides, but may have only one side.
Hereinafter, each component which comprises the composite anion exchange membrane of this invention is demonstrated.

<Surface layer>
[Anionic functional group]
The surface layer of the composite anion exchange membrane of the present invention has an anionic functional group.
As the anionic functional group, a sulfo group, a carboxy group, and a phosphoric acid group are preferable. From the viewpoint of easily adjusting the density of the anionic functional group to 3.0 equivalent / g to 10.0 equivalent / g, sulfo group Groups are more preferred.
The density of the anionic functional group is from 3.0 equivalent / g to 10.0 equivalent / g, preferably from 3.0 equivalent / g to 6.0 equivalent / g, and from 3.5 equivalent / g to 6 More preferably, it is 0.0 equivalent / g.
The method for measuring the density of the anionic functional group is as follows.
First, following the procedure for measuring the ion exchange capacity of CEM described in “194 Membrane Experimental Method (ISBN 978-4-906126-09-5)” on page 194, the amount of negative charge immobilized on the membrane per unit area was determined. taking measurement. Further, the weight of the surface layer attached to the base film per unit area is calculated from the film area, film thickness, and resin density of the measurement sample cut into a rectangle.
About a film | membrane area, it measures by the vertical x horizontal of the measurement sample cut out to the rectangle.
The film thickness is measured by performing elemental analysis in the thickness direction by X-ray electron spectroscopy (ESCA).
Regarding the resin density, the surface layer resin is scraped off from the surface of the dry film and pulverized, and the density is measured by a dry method using a gas displacement pycnometer.
From the negative charge amount and the surface layer attached weight, (negative charge amount) / (surface layer attached weight) is defined as the density of the anionic functional group (negative charge density) (equivalent / g).

The surface layer used in the present invention and the base anion exchange membrane are preferably bonded via a covalent bond.
According to the said aspect, peeling from the base film of a surface layer is prevented, and the composite anion exchange membrane by which the selectivity of a monovalent ion is maintained for a long time can be obtained.
The covalent bond includes silane coupling reaction, ene-thiol reaction, surface initiated atom transfer radical polymerization (SI-ATRP), surface initiated reversible addition-fragmentation chain transfer polymerization (SI-RAFT), dehydration condensation reaction, nucleophilic addition reaction. It is preferably a covalent bond formed by a silane coupling reaction.
As a combination of groups capable of covalent bonding, (silanol group / hydroxy group), (silanol group / silanol group) (ethylenically unsaturated group / thiol group), (ethylenically unsaturated group / ethylenically unsaturated group), (Hydroxy group / carboxy group) (isocyanato group / hydroxy group or amino group), (epoxy group / hydroxy group) and the like are preferably exemplified, and the combination of (silanol group / hydroxy group) is particularly preferable. It is not limited.

Specific examples of the covalent bond include Si—O—Si bond, Si—O—C bond, C—S—C bond, C—O—C bond, C—C bond, —NH—C (═O). —Bond, —C (═O) O— bond, —NH—C (═O) O— bond, —NH—C (═O) —NH— bond, and the like, and are Si—O—C bonds. It is preferable.
According to the said aspect, peeling from the base film of a surface layer is prevented, and the composite anion exchange membrane by which the selectivity of a monovalent ion is maintained for a long time can be obtained.
The adhesion between the surface layer and the base film can be confirmed by analyzing the spectrum corresponding to Si 2p by XPS (X-ray photoelectron spectroscopy) analysis.

[Structure represented by Formula 1]
The surface layer used in the present invention preferably has a structure represented by the following formula 1.

In Formula 1, each R ¹ independently represents an anionic functional group, and is preferably a sulfo group, a carboxy group, and a phosphate group, and more preferably a sulfo group.
i represents an integer of 1 to 5, preferably 1 to 3, more preferably 1 to 2, and still more preferably 1.
L ¹ represents an i + m-valent linking group, preferably a hydrocarbon group having 1 to 10 carbon atoms, and more preferably a saturated hydrocarbon group having 1 to 10 carbon atoms. When L ¹ represents a divalent linking group, it is preferably an alkylene group, more preferably an alkylene group having 1 to 10 carbon atoms, and still more preferably an alkylene group having 2 to 4 carbon atoms.
* Each independently represents the bonding position with the base anion exchange membrane or surface layer material. The surface layer material preferably has a structure represented by Formula 1 like the surface layer. In that case, the “structure represented by formula 1” preferably forms a siloxane bond with another Si atom of “structure represented by formula 1” at the bonding position represented by *. According to the said aspect, the composite anion exchange membrane excellent in the water permeability is obtained.
A plurality of bonding positions represented by * included in a structure in which a plurality of “structures represented by Formula 1” are bonded have at least a portion bonded to a base anion exchange membrane. preferable. According to the said aspect, the composite anion exchange membrane with which the selectivity of a monovalent ion is maintained for a long time can be obtained.
j represents an integer of 1 to 3, preferably 2 or 3, and more preferably 3.
R ² each independently represents a monovalent organic group, preferably an alkyl group, and more preferably an alkyl group having 1 to 4 carbon atoms.
k represents an integer of (3-j), and is preferably 0 or 1, more preferably 0.
m represents an integer of 1 or more, preferably an integer of 1 to 6, more preferably an integer of 1 to 4, and still more preferably an integer of 1 to 3.
When a plurality of R ¹ and R ² are present in the structure, these may be the same as or different from each other.

[Other structures]
The surface layer used in the present invention may include a structure other than the “structure represented by Formula 1”, but includes 90% by mass or more of the “structure represented by Formula 1” with respect to the total mass of the surface layer. Preferably, it is more preferably 95% by mass or more, and still more preferably 99% by mass or more.
According to the said aspect, the composite anion exchange membrane excellent in the water permeability is obtained.

[Characteristics of surface layer]
The thickness of the surface layer used in the present invention is preferably 100 to 500 nm, more preferably 100 to 400 nm, and particularly preferably 100 to 300 nm. If the thickness of the surface layer is within the above range, a composite anion exchange membrane having an excellent transport number can be obtained.
The thickness can be measured with a scanning electron microscope (SEM).

<Base anion exchange membrane>
As the base anion exchange membrane used in the present invention, known anion exchange membranes can be used without particular limitation. For example, hydrocarbon-based or fluorine-based anion-exchange membranes can be used. Exchange membranes are preferred, acrylic or styrene anion exchange membranes are more preferred, and acrylic anion exchange membranes are even more preferred.
The hydrocarbon-based anion exchange membrane in the present invention refers to an anion exchange membrane containing a hydrocarbon-containing resin.
The fluorine-based anion exchange membrane in the present invention represents an anion exchange membrane containing a resin containing a perfluoroalkylene group. Examples of the resin include a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer.
The styrene anion exchange membrane in the present invention represents an anion exchange membrane containing a resin derived from a styrene compound. Preferable examples of the styrene compound include styrene and divinylbenzene which may have a substituent.
The acrylic anion exchange membrane in the present invention represents an anion exchange membrane containing a resin derived from a compound having a (meth) acryloyl group. Preferred examples of the compound having a (meth) acryloyl group include a (meth) acrylic acid ester compound and a (meth) acrylamide compound.
Hereinafter, an acrylic anion exchange membrane will be described as an example of a base ion exchange membrane, but the present invention is not limited thereto.

[Acrylic anion exchange membrane]
The acrylic anion exchange membrane used in the present invention preferably has a resin layer supported on a porous support.
The film thickness of the acrylic anion exchange membrane as a composite including a porous support and a resin layer is preferably 10 to 250 μm, more preferably 30 to 200 μm, and particularly preferably 40 to 200 μm.
When the film thickness is within this range, the electric resistance of the film can be kept low.

-Porous support-
The acrylic anion exchange membrane used in the present invention preferably has a porous support. The porous support can be constituted as a part of the film by allowing the curable composition for film formation described later to be present in the pores of the porous support. Examples of the porous support as the reinforcing material include synthetic woven fabrics, nonwoven fabrics such as synthetic nonwoven fabrics, sponge-like films, and films having fine through holes.

The material forming the porous support in the present invention is, for example, polyethylene, polypropylene, polyacrylonitrile, polyvinyl chloride, polyester, polyamide and copolymers thereof, or, for example, polysulfone, polyethersulfone, polyphenylenesulfone, polyphenylene. Sulfide, polyimide, polyetheramide, polyamide, polyamideimide, polyacrylonitrile, polycarbonate, polyacrylate, cellulose acetate, polypropylene, poly (4-methyl-1-pentene), polyvinylidene fluoride, polytetrafluoroethylene, poly Porous membranes based on hexafluoropropylene, polychlorotrifluoroethylene and their copolymers are mentioned. Commercially available porous supports are commercially available from, for example, Mitsubishi Paper Industries Co., Ltd., Nippon Kogyo Paper Industry Co., Ltd., Asahi Kasei Fibers Co., Ltd., Japan Vilene Co., Ltd., Tapils Co., Ltd., and Freudenberg Filtration Technologies.
The porous support and the reinforcing material are required not to block the wavelength region of the energy ray, that is, to pass the irradiation of the wavelength used for the polymerization curing when performing the polymerization curing reaction by energy beam irradiation. .

Here, it is preferable that the porous reinforcing material can be penetrated by the resin layer forming composition.
The porous support preferably has hydrophilicity. In order to impart hydrophilicity to the support, general methods such as corona treatment, plasma treatment, fluorine gas treatment, ozone treatment, sulfuric acid treatment, and silane coupling agent treatment can be used.

The porous support in the present invention is preferably a nonwoven fabric, and among the nonwoven fabrics, a nonwoven fabric made of a composite fiber of polyethylene and polypropylene is preferred. The fiber diameter of the composite fiber is preferably 0.5 to 30 μm, more preferably 1 to 25 μm, and particularly preferably 2 to 20 μm.
The thickness of the porous support in the present invention is preferably 10 to 250 μm, more preferably 20 to 250 μm, still more preferably 30 to 230 μm, and particularly preferably 40 to 200 μm.

-Resin layer-
The resin layer of the acrylic anion exchange membrane used in the present invention contains an anion exchange polymer.
Each of the above anion exchange polymers is a polymer containing a unit obtained from an acryloyl group which may have an alkyl group at the α-position.
Here, the acryloyl group which may have an alkyl group at the α-position is preferably an acryloylamino group or acryloyloxy group which may have an alkyl group at the α-position, and may have an alkyl group at the α-position. An acryloylamino group is more preferred.
In the present invention, the anion exchange polymer having an anion exchange group may be any anion exchange group as long as it contains a unit obtained from an acryloyl group which may have an alkyl group at the α-position. No, but nitrogen atoms in nitrogen-containing heterocycles such as pyridinium are cationic, quaternized nitrogen atoms, aromatic heterocycle nitrogen atoms are substituted with substituents like alkylation or arylation Or those having a quaternized amino group (ie, an onio group) are preferred.
Among these, an anion exchange polymer having a unit represented by the formula IA is preferable.

In the formula IA, R ^A1 represents a hydrogen atom or an alkyl group, and R ^A2 to R ^A4 each independently represents an alkyl group or an aryl group. Here, two or more of R ^A2 to R ^A4 may be bonded to each other to form a ring. Z ^A1 represents —O— or —N (Ra) —. Here, Ra represents a hydrogen atom or an alkyl group. L ^A1 represents an alkylene group. X ^A1− represents a halogen ion or an aliphatic or aromatic carboxylate ion.

The alkyl groups of R ^A1 , R ^A2 to R ^A4 and Ra are linear or branched alkyl groups, preferably having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms, or 1 or 2 is particularly preferred and 1 is most preferred. Examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, n-hexyl, n-octyl, 2-ethylhexyl, n-dodecyl and i-decyl.

The carbon number of the aryl group of R ^A2 to R ^A4 is preferably 6 to 16, more preferably 6 to 12, and still more preferably 6 to 10. Examples include phenyl and naphthyl.
L ^A1 is preferably an alkylene group having 1 to 10 carbon atoms, more preferably 2 to 10, more preferably 2 to 6, still more preferably 2 to 4, particularly preferably 2 or 3, and most preferably 3. Examples include methylene, ethylene, propylene, hexamethylene, octamethylene, decamethylene.

Examples of the halogen ion in X ^A1− include a fluorine ion, a chlorine ion, a bromine ion, and an iodine ion.
The carbon number of the aliphatic carboxylate ion in X ^A1- is preferably 1 to 11, more preferably 2 to 7, still more preferably 2 to 5, particularly preferably 2 or 3, and most preferably 2.

The aliphatic carboxylate ion may be either a saturated hydrocarbon carboxylic acid or an unsaturated hydrocarbon carboxylic acid, but is preferably a saturated hydrocarbon carboxylic acid.
The aromatic carboxylate ion in X ^A1− is preferably an arylcarboxylate ion or a heteroarylcarboxylate ion. Here, the heteroaryl is preferably a 5- or 6-membered ring, and the ring-forming heteroatom is preferably a nitrogen atom, an oxygen atom or a sulfur atom, more preferably a nitrogen atom. The carbon number of the aromatic carboxylate ion is preferably 1 to 17, more preferably 2 to 13, and still more preferably 3 to 11. For example, benzoate ion, naphthalenecarboxylate ion, nicotinate ion, and isonicotinic acid ion can be mentioned.

The ring formed by bonding two or more of R ^A2 to R ^A4 to each other is preferably a 5- or 6-membered monocyclic or bridged ring, and preferably has 4 to 16 carbon atoms, more preferably 4 to 10 carbon atoms. preferable. Examples include pyrrolidine ring, piperazine ring, piperidine ring, morpholine ring, thiomorpholine ring, indole ring, and quinuclidine ring.

R ^A1 is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom. R ^A1 to R ^A4 are preferably a methyl group or an ethyl group. Z ^A1 is preferably —N (Ra) —, and Ra is preferably a hydrogen atom. X ^A1 is preferably a halogen atom.

Specific examples of the unit represented by the formula IA are shown below, but the present invention is not limited thereto.

The unit represented by the formula IA can be obtained from a compound represented by the following formula MA.

In Formula ^{MA, R A1 ~ R A4,} Z A1, L A1 and X ^A1 has the same meaning as ^{R A1 ~ R A4, Z A1} , L A1 and X ^A1 in Formula IA, and the preferred range is also the same.

Specific examples of the compound represented by the formula MA are shown below, but the present invention is not limited thereto.

The anion exchange polymer used in the present invention preferably has a unit obtained from a crosslinking agent in addition to the unit represented by the formula IA.
As the crosslinking agent, a polyfunctional ethylenically unsaturated compound can be used without any particular limitation.
The polyfunctional ethylenically unsaturated compound is preferably a bifunctional ethylenically unsaturated compound having two terminal ethylenically unsaturated groups.
As the terminal ethylenically unsaturated group, a (meth) acryloyl group is preferable, and a (meth) acryloyloxy group or a (meth) acrylamide group is preferable. Moreover, it is preferable that all the several terminal ethylenically unsaturated groups are the same on synthetic suitability.
The molecular weight of the polyfunctional ethylenically unsaturated compound is preferably 100 to 2,000, and more preferably 100 to 1,000.
Preferred polyfunctional ethylenically unsaturated compounds include N, N′-alkylenebis (meth) acrylamide, alkylene di (meth) acrylate, and poly (oxyalkylene) di (meth) acrylate.

It is preferable that the base anion exchange membrane used in the present invention has a hydroxy group.
In order to introduce a hydroxy group into the base anion exchange membrane, the anion exchange polymer preferably has a unit having a hydroxy group in addition to the unit represented by the formula IA.
When the anion exchange polymer has a unit having a hydroxy group, the surface layer and the base film can be easily covalently bonded.
Although it does not specifically limit as a unit which has a hydroxyl group, It is preferable to have a unit represented by the following formula IH.

In formula IH, R ^H1 has the same meaning as R ^A1 in formula IA, and the preferred range is also the same. Z ^H1 has the same meaning as Z ^A1 in formula IA, and the preferred range is also the same.
L ^H1 represents a divalent linking group, preferably an alkylene group, preferably an alkylene group having 2 to 10 carbon atoms, and more preferably an alkylene group having 2 to 4 carbon atoms.

The unit represented by the formula IH can be obtained from a compound represented by the following formula MH.

In the formula MH, ^{R H1, Z H1,} and ^{L H1} are ^{R H1, Z H1} in Formula the IH, and have the same meanings as ^{L H1,} and the preferred range is also the same.

Specific examples of the compound represented by the formula MH include hydroxyethyl (meth) acrylamide, hydroxypropyl (meth) acrylamide, hydroxybutyl (meth) acrylamide, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl. Although (meth) acrylate etc. are mentioned, this invention is not limited to these.

The base anion exchange membrane used in the present invention may contain other functional groups capable of covalent bonding, such as thiol groups and ethylenically unsaturated groups.
In order to introduce other covalently bondable functional groups into the base anion exchange membrane, the anion exchange polymer preferably has units having other covalently bondable functional groups.
The other unit having a functional group capable of covalent bonding can be obtained from a polymerizable compound having another functional group capable of covalent bonding. As the polymerizable compound, a compound having a (meth) acrylamide group or a (meth) acryloyloxy group is preferable.

-Manufacturing method of acrylic anion exchange membrane-
The acrylic anion exchange membrane used in the present invention is, for example, by applying and / or impregnating a porous support with a resin layer forming composition containing at least a compound represented by the formula MA and a polymerization initiator, It can be produced by polymerization and curing by light irradiation and / or heating.
The resin layer forming composition may further contain the crosslinking agent, polymerization inhibitor, solvent, alkali metal compound, surfactant, viscosity improver, surface tension adjusting agent, and preservative.
Acrylic anion exchange membranes can be manufactured batch-wise (fixed) using a fixed support, but membranes are manufactured continuously (continuous) using a moving support. Also good. The support may be in the form of a roll that is continuously rewound. In the case of the continuous method, a support is placed on a belt that is continuously moved, and a coating solution that is a composition for forming a polymer functional film is continuously applied, and a film is formed by polymerization and curing. And the process of performing can be performed continuously. However, only one of the coating process and the film forming process may be performed continuously.
In the case of using a temporary support, the temporary support does not need to be considered for material permeation. It does n’t matter.
In addition, you may use a temporary support body separately from a support body until the composition for resin layer formation is immersed in a support body and polymerization hardening reaction is complete | finished. The temporary support is peeled off from the film after forming the film by a polymerization curing reaction.
Such a temporary support does not need to consider material permeation, and may be any material as long as it can be fixed for film formation, including a metal plate such as an aluminum plate.

-Application method-
The resin layer forming composition can be prepared by various methods such as curtain coating, extrusion coating, air knife coating, slide coating, nip roll coating, forward roll coating, reverse roll coating, dip coating, kiss coating, rod bar coating or spray coating. The porous support can be coated or impregnated. Multiple layers can be applied simultaneously or sequentially. For simultaneous multi-layer application, curtain coating, slide coating, slot die coating and extrusion coating are preferred.

For the production of the acrylic anion exchange membrane in a continuous manner, the resin layer forming composition is continuously applied to the moving support, and more preferably, the resin layer forming composition application portion and the resin layer forming Manufactured by a production unit including an irradiation source for polymerizing and curing the composition, a film winding unit, and means for moving the support from the resin layer forming composition coating unit to the irradiation source and the film winding unit To do.

-Irradiation method-
In the said manufacturing unit, the composition application part for resin layer formation is provided in the upstream position with respect to an irradiation source, and an irradiation source is placed in the upstream position with respect to a film | membrane winding part.
In order to have sufficient fluidity when applied with a high-speed coater, the viscosity at 35 ° C. of the resin layer forming composition is preferably less than 4,000 mPa · s, more preferably 1 to 1,000 mPa · s. 1 to 500 mPa.s. s is most preferred. In the case of slide bead coating, the viscosity at 35 ° C. is preferably 1 to 100 mPa · s.

In a high-speed coating machine, the coating liquid that is a resin layer forming composition can be applied to a moving support at a speed exceeding 15 m / min, and can also be applied at a speed exceeding 20 m / min.

In particular, when a support is used to increase the mechanical strength, this support is used to improve the wettability and adhesion of the support, for example, before applying the resin layer forming composition to the surface of the support. May be subjected to corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment and the like.

The polymerization and curing of the resin layer forming composition is preferably performed within 60 seconds, more preferably within 15 seconds, particularly preferably within 5 seconds, most preferably, by applying or impregnating the resin layer forming composition to a support. Start within 3 seconds.
The light irradiation for polymerization curing is preferably less than 10 seconds, more preferably less than 5 seconds, particularly preferably less than 3 seconds, and most preferably less than 2 seconds. In the continuous method, irradiation is continuously performed, and the polymerization curing reaction time is determined in consideration of the speed at which the film-forming composition moves through the irradiation beam.

When high intensity ultraviolet rays (UV light) are used for the polymerization curing reaction, a considerable amount of heat is generated, and therefore the lamp of the light source and / or the support / film is cooled with cooling air or the like to prevent overheating. Is preferred. When a significant dose of infrared (IR light) is irradiated with the UV beam, the UV light is irradiated using an IR reflective quartz plate as a filter.

Energy rays are preferably ultraviolet rays. The irradiation wavelength is preferably matched with the absorption wavelength of any photopolymerization initiator included in the resin layer forming composition, for example, UV-A (400 to 320 nm), UV-B (320 to 280 nm). ), UV-C (280 to 200 nm).

UV sources are mercury arc lamp, carbon arc lamp, low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, swirling plasma arc lamp, metal halide lamp, xenon lamp, tungsten lamp, halogen lamp, laser and ultraviolet light emitting diode. Medium pressure or high pressure mercury vapor type ultraviolet light emitting lamps are preferred. In addition, additives such as metal halides may be present to modify the emission spectrum of the lamp. A lamp having an emission maximum at 200 to 450 nm is particularly suitable.

The energy output of the irradiation source is preferably 20 to 1,000 W / cm, preferably 40 to 500 W / cm, but may be higher or lower as long as a desired exposure dose can be realized. Absent. The polymerization hardening of the film is adjusted according to the exposure strength. The exposure dose is preferably at least 40 mJ / cm ² or more, more preferably 100 to 2 or more, as measured by the High Energy UV Radiometer (UV Power Puck ™ from EIT-Instrument Markets) in the UV-A range indicated by the apparatus. 1,000 mJ / cm ² , most preferably 150 to 1,500 mJ / cm ² . The exposure time can be chosen freely, but is preferably short and most preferably less than 2 seconds.

In addition, when the application speed is high, a plurality of light sources may be used to obtain a necessary exposure dose. In this case, the plurality of light sources may have the same or different exposure intensity.

(Production method of composite anion exchange membrane)
The method for producing a composite anion exchange membrane of the present invention comprises a coating step of coating a surface layer forming coating solution containing a silane coupling agent having an anionic functional group on one side or both sides of a base anion exchange membrane, and It includes a drying step of drying the applied coating solution for forming the surface layer.
Hereinafter, each step will be described.

<Application process>
The manufacturing method of the composite anion exchange membrane of this invention includes the application | coating process which apply | coats the coating liquid for surface layer formation containing the silane coupling agent which has an anionic functional group on the single side | surface or both surfaces of the base anion exchange membrane.
About the base anion exchange membrane, it is synonymous with what was demonstrated above, and its preferable range is also the same.

[Coating liquid for forming a surface layer containing a silane coupling agent having an anionic functional group]
The surface layer forming coating solution used in the present invention (hereinafter also simply referred to as “surface layer forming coating solution”) is a silane coupling agent having an anionic functional group (hereinafter referred to as “specific silane coupling agent”). Contain).
The surface layer forming coating solution may contain a compound other than the specific silane coupling agent in the solvent, but the content of the specific silane coupling agent with respect to the total solid content of the surface layer forming coating solution is 90% by mass. Preferably, it is 95% by mass or more, more preferably 99% by mass or more, and particularly preferably 100% by mass.
The content of the specific silane coupling agent with respect to the total mass of the surface layer forming coating solution is preferably 0.1 to 10% by mass, more preferably 0.2 to 8% by mass, and 0.5 to 5% by mass. Is more preferable.
As the specific silane coupling agent preferably used in the present invention, an alkoxysilane compound is preferably exemplified, and a trialkoxysilane compound is more preferable.
In addition, examples of the specific silane coupling agent preferably used in the present invention include compounds represented by the following formula 2.

In Formula 2, each R ²¹ independently represents an anionic functional group, and is preferably a sulfo group, a carboxy group, and a phosphate group, and more preferably a sulfo group.
i represents an integer of 1 to 5, preferably 1 to 3, more preferably 1 to 2, and still more preferably 1.
L ²¹ represents an i + m-valent linking group, preferably a hydrocarbon group having 1 to 10 carbon atoms, and more preferably a saturated hydrocarbon group having 1 to 10 carbon atoms. When L ²¹ represents a divalent linking group, it is preferably an alkylene group, more preferably an alkylene group having 1 to 10 carbon atoms, and still more preferably an alkylene group having 2 to 4 carbon atoms.
R ²³ represents an alkyl group, preferably an alkyl group having 1 to 10 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms.
j represents an integer of 1 to 3, preferably 2 or 3, and more preferably 3.
R ²² each independently represents a monovalent organic group, preferably an alkyl group, more preferably an alkyl group having 1 to 4 carbon atoms.
k represents an integer of (3-j), and is preferably 0 or 1, more preferably 0.
m represents an integer of 1 or more, preferably an integer of 1 to 6, more preferably an integer of 1 to 4, and still more preferably an integer of 1 to 3.
When a plurality of R ²¹ , R ²² and R ²³ are present in the structure, these may be the same as or different from each other.

-solvent-
The surface layer forming coating solution used in the present invention may contain a solvent.
The content of the solvent is preferably 50 to 99% by mass, more preferably 60 to 98% by mass, and still more preferably 70 to 97% by mass with respect to the total mass of the surface layer forming coating solution.

As the solvent, water or a mixed solution of a solvent having a solubility in water of 5% by mass or more and water is preferably used, and a solvent that is freely mixed with water is preferable. For this reason, the solvent selected from water and a water-soluble solvent is preferable.
As the water-soluble solvent, alcohol solvents, ether solvents that are aprotic polar solvents, amide solvents, ketone solvents, sulfoxide solvents, sulfone solvents, nitrile tolyl solvents, and organic phosphorus solvents are particularly preferable. .
Examples of the alcohol solvent include methanol, ethanol, isopropanol, n-butanol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol and the like. These can be used alone or in combination of two or more.
Examples of the aprotic polar solvent include dimethyl sulfoxide, dimethylimidazolidinone, sulfolane, N-methylpyrrolidone, dimethylformamide, acetonitrile, acetone, dioxane, tetramethylurea, hexamethylphosphoramide, hexamethylphosphorotriamide, Pyridine, propionitrile, butanone, cyclohexanone, tetrahydrofuran, tetrahydropyran, ethylene glycol diacetate, γ-butyrolactone and the like are mentioned as preferred solvents. Among them, dimethyl sulfoxide, N-methylpyrrolidone, dimethylformamide, dimethylimidazolidinone, sulfolane, Acetone, acetonitrile or tetrahydrofuran is preferred. These can be used alone or in combination of two or more.

[Coating method]
The coating method of the surface layer forming coating solution is not particularly limited, and a known method can be used.
The surface layer forming coating solution can be applied by various methods such as curtain coating, extrusion coating, air knife coating, slide coating, nip roll coating, forward roll coating, reverse roll coating, dip coating, kiss coating, rod bar coating or spray coating. It can be applied on an ion exchange membrane as a base.
In order to improve the adhesion between the base film and the surface layer, the surface of the base film is roughened with sandpaper or the like as a pretreatment for applying the surface layer forming coating solution, or corona, plasma treatment, etc. May be applied.
In particular, it is preferable that the method for producing a composite anion exchange membrane of the present invention further includes a plasma treatment step of performing plasma treatment on the base anion exchange membrane before the coating step.
According to the plasma treatment step, since a hydroxy group can be introduced to the surface of the base film, it is easy to bond the surface layer and the base film via a covalent bond.
The plasma treatment can be performed by using, for example, a commercially available atmospheric pressure plasma surface treatment apparatus.

<Drying process>
The manufacturing method of the composite anion exchange membrane of this invention includes the drying process which dries the said coating liquid for surface layer formation.
Although it does not specifically limit as a drying method, It is preferable to heat and dry.
The heating means is not limited as long as the solvent contained in the coating solution for forming the surface layer can be dried, and a heat drum, hot air, an infrared lamp, a heat oven, a heat plate heating, or the like can be used.
The drying temperature is preferably 50 ° C. or higher, more preferably 50 to 150 ° C., and still more preferably 50 to 80 ° C.
The drying time may be appropriately set in consideration of the layer thickness and the like, but is preferably 5 to 180 minutes, and more preferably 10 to 120 minutes.
In the coating process, when the surface layer forming coating solution is applied to both surfaces of the ion exchange membrane as a base, the coating process and the drying process may be alternately performed to form the surface layer on each side.

In the method for producing a composite anion exchange membrane of the present invention, the composite anion exchange membrane of the present invention can be produced in a batch system using a fixed base membrane, but the moving base You may prepare a film | membrane by a continuous type (continuous system) using a film | membrane. The base film may have a roll shape that is continuously rewound.
In the case of a continuous method, a support is placed on a belt that is continuously moved, a base membrane is formed, and the composite anion exchange membrane of the present invention is produced by further performing the coating step and the drying step. It is also possible to perform the formation of the base film and the surface layer in a continuous manner. The base film is formed, for example, by applying a resin layer forming composition and irradiating with actinic radiation.

(Ion exchange membrane module / ion exchange device)
The composite anion exchange membrane of the present invention can be suitably used in a modular form. Examples of modules include spiral, hollow fiber, pleated, tubular, plate & frame, and stack types.
Moreover, it can be set as the ion exchange apparatus which has a means for ion-exchange or desalting | purifying and refine | purifying using the anion exchange membrane module of this invention. It can also be suitably used as a fuel cell.
An example of the ion exchange apparatus of the present invention is shown in FIG. An electrodialysis layer 25 having a cation exchange membrane 23 and a composite anion exchange membrane 24 of the present invention alternately is provided between the anode electrode 21 and the cathode electrode 22, and the electrode liquid tank 11 is provided on the anode electrode 21 and the cathode electrode 22. As shown by arrows 31 and 32, the electrode solution is shared, the desalted solution is sent from the desalted solution tank 12 to the arrows 33 and 34, and the concentrated solution is sent from the concentrate tank 13 to the arrows 35 and 36. Each circulates as shown.

Hereinafter, the present invention will be described more specifically with reference to examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. Unless otherwise specified, “part” and “%” are based on mass.

(Manufacture of base film)
A coating solution having the composition of base film B-1 shown in Table 1 below was manually applied to an aluminum plate at a speed of about 5 m / min using a 150 μm wire winding rod. Subsequently, the coating liquid applied to the aluminum plate was brought into contact with a non-woven fabric (FO-2223-10 manufactured by Freudenberg, thickness: 100 μm) as a support, and the support was impregnated with the coating liquid. Subsequently, the excess coating liquid was removed from the nonwoven fabric using a rod on which no wire was wound. The temperature of the coating solution at the time of coating was about 50 ° C. Thereafter, the support was impregnated with the coating solution by using a UV exposure machine (Fusion UV Systems, Model Light Hammer LH6, D-bulb, speed 10 m / min, 100% strength) to polymerize and cure the film. Produced. The exposure amount was 1,000 mJ / cm ² in the UV-A region. The obtained film was removed from the aluminum plate and stored in a 0.1 M NaCl aqueous solution for at least 12 hours to produce a 140 μm thick resin layer carried on a nonwoven fabric (support). Thereby, a base film B-1 was obtained. The base film B-2 and the base film B-2 were prepared in the same manner as in the production of the base film B-1, except that the coating liquid had the composition of the base film B-2 or B-3 shown in Table 1. B-3 was produced.

Details of the compounds described in Table 1 are shown below. In addition, the unit of the numerical value in each component column of the composition in Table 1 is a mass part of an active ingredient. Further, “-” in the table means that the component is not contained.
ATMAC: Compound having the following structure (manufactured by Kj Chemicals)
MBA: Methylenebisacrylamide (manufactured by Tokyo Chemical Industry Co., Ltd.)
Hydroxyethylacrylamide (manufactured by Kj Chemicals)
Hydroxybutyl acrylate (manufactured by Nippon Kasei Co., Ltd.)
Pure water: Pure water (Wako Pure Chemical Industries, Ltd.)
IPA: Isopropyl alcohol (Wako Pure Chemical Industries, Ltd.)
MEHQ: Hydroquinone monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.)
LiNO ₃ : Lithium nitrate (Wako Pure Chemical Industries, Ltd.)
Tegoglide 432: polyether-modified siloxane copolymer (Evonik)
Darocur 1173: 2-hydroxy-2-methyl-1-phenyl-propan-1-one (manufactured by BASF)

(Examples 1 to 81 and Comparative Examples 1 to 57)
<Formation of surface layer>
According to the composition shown in Table 2 below, surface layer forming coating solutions S-1 to S-10 were prepared. The base membrane stored in a 0.1 M NaCl aqueous solution was washed with pure water, and both sides were wiped with dry filter paper. In each of the examples and comparative examples, surface treatment such as plasma treatment was performed as necessary, and then the surface layer forming coating solutions shown in Tables 3 to 18 were applied. In Tables 3 to 18, the example described as “plasma” in the column of the base film surface treatment indicates that the surface treatment was performed by the plasma treatment, and the example described as “none” did not perform the surface treatment. Each shows that. Plasma treatment was performed at 500 W · min / m ² by supplying nitrogen at 15 L / min and oxygen at 1.5 L / min using an atmospheric pressure plasma surface treatment apparatus.
Subsequently, drying at the drying temperature and drying time described in Tables 3 to 18 was performed using an oven. Thereafter, Examples 28 to 54 and Comparative Examples 22 to 39 were immersed in a 0.01 M aqueous sodium hydroxide solution at room temperature for 2 hours after the drying as a post-process. Subsequently, it was immersed in a 0.5 M saline solution to remove sodium hydroxide in the membrane.
After the surface layer forming step including the subsequent step, it was stored in a 0.1 M NaCl solution for at least 12 hours. Thus, the composite anion exchange membrane of the Example and the comparative example was produced.
In all Examples, the existence of the Si—O—C structure was confirmed from the spectrum corresponding to Si 2p by XPS analysis.

<Evaluation of permeation anion selectivity>
Electrodialysis was performed using an electrodialyzer microacylator S1 manufactured by Astom Co., Ltd.
As the anion exchange membrane, a composite anion exchange membrane (hereinafter also referred to as “AEM”) as an example or a comparative example was used, and as the cation exchange membrane (hereinafter also referred to as “CEM”), CMX ((stock) ) Manufactured by Astom). The flow of the apparatus is shown in FIG. In FIG. 2, arrows 31 and 32 indicate the movement of the electrode solution, arrows 33 and 34 indicate the movement of the desalting solution, and arrows 35 and 36 indicate the movement of the concentrated solution, respectively.
As raw water, an aqueous solution of sodium nitrate 0.1M and sodium sulfate 0.05M was used. As the electrode solution, a 0.5 M sodium sulfate aqueous solution was used. The raw water is supplied at a flow rate of 50 mL / min as a desalted solution and concentrated solution to an electrodialysis tank in which four CEMs and three AEMs are alternately stacked, and the current is 50 mA / min. At that point, the power supply was stopped.
The ion composition of the desalting chamber was quantified by ion chromatography, and the removal rate of nitrate ion and sulfate ion was calculated by the following formula.
(Removal rate) = ((ion concentration before electrodialysis) − (ion concentration after electrodialysis)) / (ion concentration before electrodialysis) × 100
Subsequently, permeation anion selectivity was calculated according to the following equation.
(Permeation anion selectivity) = (nitrate ion removal rate) / (sulfate ion removal rate)

<Evaluation of change in selectivity over time>
After evaluating the permeation anion selectivity (also referred to as “selectivity before energization”), the flow of the apparatus was changed as shown in FIG.
The electrode solution was replaced and the desalted solution was replaced with raw water. Subsequently, raw water was supplied as a desalting solution to the electrodialysis tank at a flow rate of 100 mL / min, and energized at a current value of 50 mA for 5 hours. Thereafter, the apparatus was reassembled into the configuration shown in FIG. 2, and the selectivity after energization was measured again in the same manner as in the evaluation of the permeation anion selectivity.
The change in selectivity before and after the energization for 5 hours was evaluated as follows.
Change in selectivity over time (%) = (selectivity after energization) / (selectivity before energization) × 100
For the examples where the permeation anion selectivity (“selectivity before energization”) was 1.1 or less, this evaluation was not performed because there was no permeation anion selectivity, and “−” was described in the result column.

<Measurement of transport number of composite anionic exchange membrane>
The transport number was calculated by measuring the membrane potential (V) by static membrane potential measurement.
Two electrolytic cells (cells) were separated by a composite anionic exchange membrane to be measured. Prior to measurement, the composite anionic exchange membrane was equilibrated in 0.05 M NaCl aqueous solution for about 16 hours. Thereafter, NaCl aqueous solutions having different concentrations were respectively poured into the electrolytic cells on the opposite sides of the composite anionic exchange membrane to be measured. Specifically, 100 mL of 0.05 M NaCl aqueous solution was poured into one cell. Moreover, 100 mL of 0.5M NaCl aqueous solution was poured into the other cell.
The temperature of the NaCl aqueous solution in the cell was stabilized at 25 ° C. by a constant temperature water bath. Next, while flowing both solutions toward the membrane surface, both electrolytic cells and an Ag / AgCl reference electrode (manufactured by Metrohm, Switzerland) were connected with a salt bridge to measure the membrane potential (V), and the following formula (II) ) To calculate the transport number t.
The effective area of the composite anionic exchange membrane was 1 cm ² .
t = (a ′ + b ′) / 2b ′ Formula (II)
The detail of each code | symbol in the said Formula (II) is shown below.
a ′: membrane potential (V)
b ′: 0.5915 log (f1c1 / f2c2) (V)
f1, f2: NaCl activity coefficient of both cells c1, c2: NaCl concentration (M) of both cells

<Measurement of water permeability WP (mL / m ² / Pa / hr)>
400 mL of the feed solution and 400 mL of the draw solution were brought into contact with each other through a composite anionic exchange membrane (membrane contact area 18 cm ² ), and each solution was allowed to flow at a flow rate of 0.11 cm / sec using a peristaltic pump. The rate at which water in the feed solution penetrates the draw solution through the composite anionic exchange membrane is analyzed by measuring the mass of the feed solution and the mass of the draw solution in real time, and the water permeability (mL / m ² / Pa / hr) was determined.

<Measurement of density (negative charge density) of anionic functional groups in surface layer>
First, following the procedure for measuring the ion exchange capacity of CEM described in “194 Membrane Experimental Method (ISBN 978-4-906126-09-5)” on page 194, it is immobilized on a composite anionic exchange membrane per unit area. The amount of negative charge was measured. On the other hand, the surface layer adhesion weight to the base film per unit area was obtained from the film area, thickness, and resin density of the measurement sample.
About the film | membrane area, it measured by the length x width of the measurement sample cut out to the rectangle.
The film thickness was measured by elemental analysis in the thickness direction by X-ray electron spectroscopy (ESCA).
Regarding the resin density, the surface layer resin was scraped off from the dry film surface and pulverized, and the density was measured by a dry method using a gas displacement pycnometer.
(Negative charge amount) / (attached weight) was defined as an anionic functional group (negative charge density) (equivalent / g).
For the case where the surface layer was peeled off when immersed in water after drying, this measurement was not performed and “-” was written in the result column.

<Measurement of surface layer thickness>
Elemental analysis in the thickness direction was performed by X-ray electron spectroscopy (ESCA), and the existence range of Si was defined as the film thickness.
For the example in which the surface layer was peeled off when immersed in water after drying, this measurement was not performed, and “0” was described in the result column.

Details of the compounds described in Table 2 are shown below. In addition, the unit of the numerical value in each component column of the composition in Table 2 is a mass part of an active ingredient. Further, “-” in the table means that the component is not contained.
3- (Trihydroxysilyl) -1-Propanesulfonic Acid: (Gelest)
3- (Triethoxysilyl) propylsuccinic anhydride: (Gelest)
N- (Trimethoxysilylpropyl) Ethylenediamine Triacetic Acid, Trisodium Salt: (Gelest)
1M HCl: (manufactured by Sigma Aldrich)
Sodium polystyrene sulfonate (number average molecular weight 70,000): (manufactured by Sigma-Aldrich)

1 base anion exchange membrane, 2 surface layer, 11 electrode liquid tank, 12 desalted liquid tank, 13 concentrate tank, 21 anode electrode, 22 cathode electrode, 23 cation exchange membrane, 24 composite anion exchange membrane, 25 electrodialysis Layer, 31, 32 Electrode solution transfer, 33, 34 Desalination solution transfer, 35, 36 Concentrate transfer

Claims (9)

1. Having a surface layer having an anionic functional group on one or both sides of the base anion exchange membrane,
   A composite anion exchange membrane wherein the density of anionic functional groups in the surface layer is 3.0 equivalent / g to 10.0 equivalent / g.
2. The composite anion exchange membrane according to claim 1, wherein the surface layer and the base anion exchange membrane are bonded via a covalent bond.
3. The composite anion exchange membrane according to claim 1 or 2, wherein the anionic functional group is a sulfo group, a carboxy group, or a phosphate group.
4. The composite anion exchange membrane according to any one of claims 1 to 3, wherein the surface layer has a structure represented by the following formula 1.
   

   

   
   In Formula 1, each R ¹ independently represents an anionic functional group,
   i represents an integer of 1 to 5;
   L ¹ represents an i + m-valent linking group,
   * Each independently represents the bonding position with the base anion exchange membrane or surface layer material,
   j represents an integer of 1 to 3,
   Each R ² independently represents a monovalent organic group,
   k represents an integer of (3-j),
   When a plurality of R ¹ and R ² are present in the structure, these may be the same or different from each other,
   m represents an integer of 1 or more.
5. The composite anion exchange membrane according to any one of claims 2 to 4, wherein the base anion exchange membrane has a hydroxy group.
6. A coating step of applying a coating solution for forming a surface layer containing a silane coupling agent having an anionic functional group on one side or both sides of a base anion exchange membrane; and
   A drying step of drying the applied coating solution for forming the surface layer,
   A method for producing a composite anion exchange membrane comprising:
7. A plasma treatment step of performing a plasma treatment on the base anion exchange membrane before the coating step;
   The method for producing a composite anion exchange membrane according to claim 6, further comprising:
8. An ion exchange membrane module comprising the composite anion exchange membrane according to any one of claims 1 to 5.
9. An ion exchange apparatus comprising the composite anion exchange membrane according to any one of claims 1 to 5.

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