TW201514102A - Electrode, producing method thereof and flow through capacitor using the same - Google Patents

Abstract

To provide an electrode having a small electrode resistance, being excellent in durability, and preferably used as an electrode for a flow through capacitor. The electrode is an electrode comprising a current collector, a porous electrode layer and an ion exchange layer both formed there, wherein the porous electrode layer includes a carbon material; the ion exchange layer includes an ion exchanger (A), the ion exchanger comprising; (1) a copolymer (A1+A2) comprising a vinyl alcohol type monomer (A-1) and an ion exchangeable monomer (A-2) or (2) a mixture (B1+B2) comprising a vinyl alcohol type polymer (B-1) and a polymer having an ion exchangeable group (B-2), and the ion exchanger is cross-linked with a cross linking agent to produce an acetal cross linkage at a degree being equal to or less than 4.30.

Description

Electrode and manufacturing method thereof, and liquid-passing capacitor using the same [Related patent application]

The patent application claims priority based on the Japanese Patent Application No. 2013-142978 filed on Jul. 8, 2013, and the Japanese Patent Application No. 2013-142979, filed on the same date. All contents of both cases are cited as part of this application by reference.

The present invention relates to an electrode having a current collector layer, a porous electrode layer, and an ion exchange layer, and a method of manufacturing the same. In addition, a liquid-through type capacitor using such an electrode is also known. Further, a desalination apparatus having such a liquid-pass type capacitor and a desalination method using the same are also known.

A liquid-pass type capacitor (through-type electric double-layer capacitor) is used for the removal and composition change of a substance contained in a gas, a liquid (aqueous solution and a non-aqueous solution). The liquid-through type capacitor generally has an electrode which is an electrode layer having a high surface area, and a flow path which is provided between the electrodes. The removal of the substance and the change of the composition are carried out by electrostatic adsorption, electrochemical reaction, catalytic decomposition, or the like using the electrode.

So far, some reports have mentioned that the liquid type will be The container is used for desalination of water containing an ionic substance, and the electrode is used for electrostatic adsorption of ions.

In general, desalination is carried out by a liquid-through capacitor. The two steps are repeated: a desalting step (ion adsorption step) is performed by applying a DC voltage between the electrodes of the liquid-passing capacitor, whereby ions in the water supplied between the electrodes are adsorbed between the electrodes, and then the ionicity is removed. The water recovery of the substance and the electrode washing step (ion desorption step) are performed by reversing the direct current power supply or short-circuiting the electrodes, thereby desorbing ions adsorbed to the respective electrodes to regenerate the electrodes.

In the following Patent Documents 1 and 2, the liquid essence is described. A liquid-through type capacitor used for the purpose of fixing a column for charge chromatography. In the liquid-pass type capacitor, the first conductive support layer, the first high surface area conductive layer, the first non-conductive porous spacer layer, the second conductive support layer, and the second high surface area are used. A group of adjacent layers of the conductive layer and the second non-conductive porous spacer layer. Further, it is also described that the liquid-pass type capacitor can be used for purification of water containing an ionic substance such as sodium chloride. In Patent Document 2, in addition to the above-described liquid-pass type capacitor, there is also described a liquid-through type capacitor in which a washer-type electrode is formed of a conductive support gasket and a high-surface-area conductive gasket. And non-conductive spacer gaskets are laminated.

In contrast, some reports suggest some use in the electrode layer A liquid-through type capacitor in which an electrode of an ion exchange membrane is provided on the surface. When desalination is carried out by using such a liquid-through type capacitor, in the desalting step, a charge having the same polarity sign as that of the fixed charge of the ion exchange membrane is applied to the electrode, and in the electrode cleaning step, the fixed charge of the ion exchange membrane is applied to the electrode. The charge of the polarity symbol. In the desalting step, the secondary ions desorbed from the electrode are blocked from being discharged outside the electrode by the ion exchange membrane, and the current efficiency is thereby improved. Further, in the electrode washing step, the above-described adsorption of the deionized ions by the electrode pair is prevented by the aforementioned ion exchange membrane.

Patent Document 3 discloses a liquid-through type capacitor in which an electrode of a porous electrode is adjacent to an ion exchange membrane. Further, many polymers having an ionic group which can be used as the aforementioned ion exchange membrane are exemplified. Patent Document 4 describes an electrode assembly comprising: an electrode comprising a porous material, capable of adsorbing ions having a sign charge having a polarity opposite to an electrode charge; and an ion exchange material in contact with the electrode. In Patent Document 4, an ion conductive polymer is described as the ion exchange material.

The liquid-pass type capacitor described in Non-Patent Document 1 below has an electrode formed by applying a cation exchange resin to the surface of a carbon electrode. In the non-patent document 1, it is disclosed that the cation exchange resin on the surface of the electrode can be treated with sulfosuccinic acid after the polyvinyl alcohol is coated on the surface of the electrode, thereby performing crosslinking and sulfonic acid. The base is introduced; at this time, the intermolecular phase of the polyvinyl alcohol is crosslinked by an ester bond.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] U.S. Patent No. 5,192,432

[Patent Document 2] Japanese Patent Laid-Open No. Hei 5-258992

[Patent Document 3] US Patent No. 6709560

[Patent Document 4] Japanese National Patent Publication No. 2010-513018

[Non-patent literature]

[Non-Patent Document 1] J. Membr. Sci., Vol. 355, p. 85 (2010)

In the liquid-pass type capacitors described in Patent Documents 1 and 2, there is a problem in the desalination step that the secondary ions (the ions having the same polarity symbolic charge as the electrode charges) adsorbed to the electrodes block the opposite ions that should be adsorbed. The problem of adsorption of (the ion having a sign charge opposite to the polarity of the electrode charge), and the desorption of the auxiliary ion to the outside of the electrode, and mixing into the desalted water cause a problem of a decrease in current efficiency. Further, in the electrode cleaning step, there is a problem in that ions desorbed from the electrode due to the reverse connection of the DC power source are again adsorbed by the electrode having a sign charge opposite to the charge of the ion, and the electrode is contaminated.

On the other hand, when the desalination capacitors of the electrodes of the ion exchange membrane are provided on the surface of the electrode layer in Patent Documents 3 and 4, the charge of the same polarity as the fixed charge of the ion exchange membrane is applied to the electrode in the desalination step. In the electrode cleaning step, a charge opposite to the fixed polarity of the fixed charge of the ion exchange membrane is applied to the electrode. In the desalting step, the secondary ions desorbed from the electrode are blocked from being discharged outside the electrode by the ion exchange membrane, and the current efficiency is thereby improved. Further, in the electrode washing step, the aforementioned adsorption of the deionized ions by the electrode pair is prevented by the aforementioned ion exchange membrane.

However, the current efficiency of the liquid-through type capacitors described in Patent Documents 3 and 4 is still insufficient.

Non-patent document 1 discloses cation intersection on the surface of the electrode The resin-replaceable system can treat the polyvinyl alcohol with sulfosuccinic acid after coating the surface of the electrode, thereby performing cross-linking and sulfonic acid group introduction; at this time, the intermolecular phase of the polyvinyl alcohol is cross-linked by ester bonds. . However, since the ester bond is low in resistance to an alkaline agent, there is a problem that cleaning is difficult when the electrode surface is contaminated. Further, there is also a problem that the introduction amount of the sulfonic acid group is small, and the current efficiency of the liquid-pass type capacitor is not good enough.

The present invention is to solve the above problems (low current efficiency) The researcher aims to provide an electrode which is suitable for use as an electrode for a liquid-pass type capacitor and a method for producing the same. Further, another object of the present invention is to provide a liquid-pass type capacitor having excellent current efficiency in the removal (desalting) of an ionic substance, separation of an ionic substance from a nonionic substance, and the like. Further, another object of the present invention is to provide a desalination apparatus using the liquid-pass type capacitor and a desalination method using the same.

The inventors of the present invention have found that in the ion exchange layer provided on the surface of the electrode, the ion exchange layer contains a polyvinyl alcohol-based material and cross-links the polyvinyl alcohol-based material. At the time of the treatment, the control of the degree of crosslinking has a significant influence on the durability and current efficiency of the electrode, and the present invention has been completed.

According to a first aspect of the present invention, an electrode is an electrode in which a porous electrode layer and an ion exchange layer are formed on a current collector layer; the porous electrode layer contains a carbon material; and the ion exchange layer contains an ion exchanger (A). And the aforementioned ions The exchanger (A) contains (1) a copolymer (A1+A2) composed of a vinyl alcohol monomer (A-1) and an ion-exchangeable monomer (A-2), or (2) a vinyl alcohol system. a mixture (B1+B2) of a polymer (B-1) and a polymer (B-2) having an ion exchange group, and the aforementioned ion exchange system is crosslinked by forming an acetal cross-linking crosslinking agent, and cross-linking thereof The range of degrees is below 4.30.

Preferably, in the ion exchanger (A), the molar ratio of the vinyl alcohol unit and the ion exchange unit in the copolymer or the mixture is 99.5:0.5 to 50:50.

Preferably, in the ion exchanger (A), the copolymer (A1+A2) is formed by a vinyl alcohol polymer (a-1) and a polymer (a-2) having an ion exchange group. Block copolymer.

Preferably, in the ion exchanger (A), the copolymer (A1+A2) is a mixture of a vinyl alcohol polymer (a-1) and a polymer (a-2) having an ion exchange group. Graft copolymer.

Preferably, the porous electrode layer and the ion exchange layer formed on the current collector layer are laminated in the order of the current collector layer/porous electrode layer/ion exchange layer.

Preferably, the thickness of the ion exchange layer formed on the porous electrode layer is 70 μm or less, and the thickness of the porous electrode layer is in the range of 100 μm to 1000 μm.

Preferably, the ion exchange layer is impregnated into the porous electrode layer. Here, "impregnation" also means a state in which the porous electrode layer is substantially integrated with the porous electrode layer and is not confirmed on the porous electrode layer, while having practical gas permeability.

The above electrode system is preferably used as a liquid-pass type capacitor Extremely used.

According to a second aspect of the present invention, in the method of producing an electrode, a slurry containing a carbon material and a solution containing the ion exchanger (A) are simultaneously or separately applied to the surface of the current collector layer, and then the coating film is dried to carry out crosslinking. Thereby, the porous electrode layer and the ion exchange layer are formed.

In the method for producing an electrode described above, a slurry containing the carbon material and a solution containing the ion exchanger (A) may be simultaneously applied onto the surface of the current collector layer.

In the method for producing an electrode described above, after the slurry containing the carbon material is applied, a solution containing the ion exchanger (A) may be applied to the surface of the slurry.

In the method for producing the electrode, it is preferred to carry out the crosslinking treatment after the coating film is dried, or after heat treatment or without heat treatment.

According to a third aspect of the present invention, a liquid-pass type capacitor is characterized in that the electrodes are disposed to face each other, and a flow path portion is formed between the electrodes, wherein the ion exchanger (A) in one of the electrodes is a cation having an anionic group. The exchange layer is composed of (1) a copolymer of the above vinyl alcohol monomer and a cation exchange monomer or (2) a mixture of the above vinyl alcohol polymer and the aforementioned cation exchange polymer, and the other The ion exchanger in the electrode is an anion exchange layer having a cationic group, and (3) is composed of a copolymer of the above vinyl alcohol monomer and an anion exchange monomer or (4) is composed of the above vinyl alcohol polymer. The mixture of the anion exchange polymer is a composition, and the anion exchange layer and the cation exchange layer are disposed to face each other with the flow path portion interposed therebetween.

A fourth aspect of the present invention is a desalination device, characterized by The liquid-pass type capacitor, the container for accommodating the liquid-pass type capacitor, and a DC power source, wherein the positive electrode and the negative electrode of the DC power source are exchangeably connected to the respective electrodes, and the container has a solution for desalination by a liquid-through type capacitor The liquid supply port of the ionic substance and the discharge port of the liquid after desalting.

The fifth aspect of the present invention is a desalination method which is a desalination method of a liquid containing an ionic substance by using a desalination apparatus, and the desalination method is characterized by the following steps: the first step is to use an electrode having an anion exchange layer as The positive electrode and the electrode having the cation exchange layer are negative electrodes, and a voltage is applied to each electrode by a DC power source, and a liquid containing an ionic substance is supplied to a flow path portion between electrodes to which a voltage is applied, and ions in the liquid are made of a porous electrode layer. Adsorption, and then discharging the liquid for recovery; and in the second step, the liquid is supplied to the flow path portion, the electrode having the anion exchange layer is the negative electrode, the electrode having the cation exchange layer is the positive electrode, and the electrodes are applied by the DC power source. The voltage is thereby desorbed by the ions adsorbed by the porous electrode layer in the first step, and then the liquid containing the desorbed ions is discharged.

In addition, any combination of at least two constituent elements disclosed in the scope of the patent application and/or the specification is covered by the present invention. In particular, any combination of two or more claims described in the patent application scope is covered by the present invention.

The electrode of the present invention is capable of being immersed in water An electrode that maintains a good appearance for a long period of time is an electrode that is excellent in interface adhesion and can reduce electrode resistance. Therefore, the liquid-pass type capacitor using the above-described electrode can perform desalination and separation of an ionic substance and a nonionic substance with high efficiency and stability for a long period of time. Further, according to the production method of the present invention, it is possible to further suppress the bubbles appearing on the surface of the electrode, and it is possible to obtain an electrode having improved affinity at the electrode interface and higher homogeneity.

1‧‧‧ Liquid-through capacitor

2, 3, 23‧‧‧ electrodes

4‧‧‧ anion exchange layer

5, 8, 25‧‧‧ porous electrode layer

6, 9‧‧‧ collector layer

7‧‧‧Cation exchange layer

10‧‧‧Flow Department

11, 14‧‧ anions

12, 13‧‧‧ cation

15‧‧‧Desalting device

16‧‧‧ Container

17‧‧‧DC power supply

18‧‧‧ supply port

19‧‧‧Export

20‧‧‧ capacitor unit

21‧‧‧through holes

22‧‧‧Titanium electrode

24‧‧‧Parts

26‧‧‧Introduced vinyl alcohol polymer layer with cationic unit (cationic polymer layer)

The invention will be more clearly understood from the following description of the preferred embodiments. The embodiments and the drawings are merely for the purpose of illustration and description, and are not intended to limit the scope of the invention. The scope of the invention is defined by the scope of the patent application.

Fig. 1 is a view showing an example of a state in which ions are adsorbed by a liquid-pass type capacitor using the electrode of the present invention.

Fig. 2 is a view showing an example of a state in which ions are removed by a liquid-pass type capacitor using the electrode of the present invention.

Fig. 3 is a schematic view showing an example of a desalination apparatus having a liquid-through type capacitor of the present invention.

Fig. 4 is an exploded perspective view showing a liquid-pass type capacitor in the desalination apparatus of the present invention.

Fig. 5 is a view showing a method of measuring the electrode resistance of the embodiment.

Fig. 6 is an electron microscope image of a cross section of a porous electrode layer and a vinyl alcohol polymer layer in the electrode of Example 1.

Fig. 7 is a map obtained by the total reflection method (ATR method) of infrared spectroscopy (FT-IR) for the electrode prepared in Example 1.

Fig. 8 is an electron microscope image of a cross section of a porous electrode layer and a vinyl alcohol polymer layer in the electrode of Example 18.

Fig. 9 is a map obtained by the total reflection method (ATR method) of infrared spectroscopy (FT-IR) for the electrode prepared in Example 18.

[Formation of the Invention] (electrode)

The electrode of the present invention is an electrode in which a porous electrode layer and an ion exchange layer are formed on a current collector layer, wherein the porous electrode layer contains a carbon material, and the ion exchange layer contains an ion exchanger (A). And the ion exchanger (A) contains (1) a copolymer (A1+A2) composed of a vinyl alcohol monomer (A-1) and an ion-exchangeable monomer (A-2), or (2) a mixture (B1+B2) of a vinyl alcohol-based polymer (B-1) and a polymer (B-2) having an ion exchange group, and the aforementioned ion exchange system is crosslinked by forming an acetal cross-linking crosslinking agent. The degree of crosslinking of the ion exchanger is in the range of 4.30 or less.

The electrode system of the present invention can efficiently adsorb and desorb ions while maintaining excellent durability. The adsorption and desorption of ions by the electrode of the present invention is carried out in a porous electrode layer. The adsorption and desorption of ions is performed by applying a voltage to the electrodes to impart an electric charge to the porous electrode layer to generate an electrostatic force between the porous electrode layers and the ions.

One surface of the porous electrode layer may be adjacent to or opposed to the current collector layer, and the porous electrode layer and the current collector layer may be electrically connected. The connection of the aforementioned electrode to an external power source is usually performed by a part of the collector layer It is electrically connected to an external power source. By connecting the above electrode to an external power source as described above, it is possible to impart a charge to the porous electrode layer.

The other surface of the porous electrode layer may face the ion exchange layer. When the electrode of the present invention is used for adsorption and desorption of ions, most of the movement of ions between the porous electrode layer and the outside of the electrode proceeds through the ion exchange layer. The ion exchange layer has a fixed charge derived from the ion-exchange polymer, and thus selectively passes ions having a sign polarity opposite to that of the charge of the ionic group. By performing ion movement by the ion exchange layer having the ion selectivity as described above, it is possible to suppress a decrease in adsorption and desorption efficiency when the ions are adsorbed and desorbed repeatedly.

(ion exchange layer)

In the electrode of the present invention, an ion exchange layer containing an ion exchanger (ion exchange polymer) is used for the ion exchange layer disposed on the porous electrode layer. This ion exchange layer has not only a small film resistance, but also easy passage of ions and excellent ion selectivity. In addition, the ion exchange layer also has excellent strength and organic pollution resistance. By using the ion exchange layer as described above, the electrode of the present invention can stably perform adsorption and desorption of ions with high efficiency and long period of time.

(polymer with anion exchange group)

An ion-exchangeable polymer having an anion exchange group (sometimes referred to as a cationic polymer) used in the present invention (including a random copolymer with a vinyl alcohol monomer and a cationic property constituting the block copolymer) The polymer (A1+A2; B-2) is a main chain, a side chain, and an end as long as it is a monomer having an anion exchange group (sometimes referred to as a cationic group) in the molecule. It is also possible to have a cationic group at any position. As the cationic group, an ammonium group, an ammonium imino group, a fluorenyl group, a fluorenyl group or the like is exemplified. Further, a polymer having an amine group and an imine group having a functional group in which a part of water can be converted into an ammonium group and an ammonium imino group is also a cationic group-containing polymer of the present invention. Among them, from the viewpoint of easy availability on an industrial scale, an ammonium group is preferred. As the ammonium group, any of a primary ammonium group (ammonium salt), a secondary ammonium group (ammonium salt), a tertiary ammonium group (salt), a quaternary ammonium group (trialkylammonium group, etc.) can be used. However, a quaternary ammonium group (trialkylammonium group) is preferred. The cationic polymer may contain only one cationic group or a plurality of cationic groups. Further, the anion of the cationic group is not particularly limited, and examples thereof include a halide ion, a hydroxide ion, a phosphate ion, and a carboxylic acid ion. Among them, from the viewpoint of easiness of obtaining, a halide ion is preferred, and a chloride ion is more preferred. The cationic polymer may contain only one pair of anions and may also contain a plurality of pairs of anions.

As the cationic polymer, a cationic polymer having a structural unit of the following general formulae (1) to (8) is exemplified.

[wherein R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ² , R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group, an aryl group or an aralkyl group having 1 to 18 carbon atoms which may have a substituent. R ² , R ³ and R ⁴ may be bonded to each other to form a saturated or unsaturated cyclic structure. The Z system represents -O-, -NH- or -N(CH ₃ )-, and the Y system represents a divalent bond group having a total carbon number of 1 to 8 which may contain an oxygen, nitrogen, sulfur or phosphorus atom. The X ^- line represents an anion].

The anion X ^- in the formula (1) is exemplified by a halide ion, a hydroxide ion, a phosphate ion, a carboxylic acid ion or the like. The cationic polymer having a structural unit represented by the general formula (1) is exemplified by 3-(methyl)acrylamidopropyltrimethylammonium chloride and 3-(methyl)acrylamide. A homopolymer or copolymer of a 3-(methyl) acrylamide-alkyltrialkylammonium salt such as 3,3-dimethylpropyltrimethylammonium chloride.

[wherein R ⁵ represents a hydrogen atom or a methyl group. R ² , R ³ , R ⁴ and X ^- are synonymous with the above formula (1).

The cationic polymer containing a structural unit represented by the formula (2) is a homopolymer or a copolymer of a vinylbenzyltrialkylammonium salt such as vinylbenzyltrimethylammonium chloride. .

[wherein, R ² , R ³ and X ^- are synonymous with the above formula (1)].

[wherein, R ² , R ³ and X ^- are synonymous with the above formula (1)].

In the case of the cationic polymer containing the structural unit represented by the general formula (3) and the general formula (4), it is exemplified that diallyldimethylammonium chloride or the like can be carried out from a diallyldialkylammonium salt. A homopolymer or copolymer obtained by cyclization polymerization.

[wherein n represents 0 or 1. R ² and R ³ are each synonymous with the formula (1).

The cationic polymer containing a structural unit represented by the formula (5) is exemplified by a homopolymer or a copolymer of acrylamine.

[wherein n represents 0 or 1. R ² , R ³ , R ⁴ and X ^- are each synonymous with the formula (1).

The cationic polymer containing a structural unit represented by the formula (6) is a homopolymer or a copolymer of an allyl ammonium salt such as acrylamine hydrochloride.

Wherein R ⁵ represents a hydrogen atom or a methyl group, and A represents -CH(OH)CH ₂ -, -CH ₂ CH(OH)-, -C(CH ₃ )(OH)CH ₂ -, -CH ₂ C(CH ₃ )(OH)-, -CH(OH)CH ₂ CH ₂ - or -CH ₂ CH ₂ CH(OH)-. The E system represents -N(R ⁶ ) ₂ or -N ⁺ (R ⁶ ) ₃ . X ^- and R ⁶ represent a hydrogen atom or a methyl group. The X ^- line represents an anion).

In the case of a cationic polymer containing a structural unit represented by the general formula (7), homopolymerization of N-(3-allyloxy-2-hydroxypropyl)dimethylamine or a quaternary ammonium salt thereof is exemplified. A homopolymer or copolymer of a compound or copolymer, N-(4-allyloxy-3-hydroxybutyl)diethylamine or a quaternary ammonium salt thereof.

Wherein R ⁵ represents a hydrogen atom or a methyl group, R ⁷ represents a hydrogen atom, a methyl group, an ethyl group, an n-propyl group or an i-propyl group, and R ⁸ represents a hydrogen atom, a methyl group or an ethyl group] .

The cationic polymer containing a structural unit represented by the general formula (8) is exemplified by (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (methyl). Acrylamide, N,N-dimethyl(meth)acrylamide, and the like.

(polymer with cation exchange group)

The ion-exchangeable polymer having a cation exchange group (sometimes referred to as an anionic polymer) (A1+A2; B-2) used in the present invention is a polymerization containing a cation exchange group (sometimes called an anion group) in a molecule. Things. It is possible to contain the anion group at any position of the main chain, the side chain, and the end. The anion group is exemplified by a sulfonate group, a carboxylate group, a phosphonate group and the like. Further, a functional group having a sulfonic acid group, a carboxyl group, a phosphonic acid group or the like which can be converted into a sulfonate group, a carboxylate group or a phosphonate group in at least a part of water also belongs to an anionic group. Among them, from the viewpoint of a large ion dissociation constant, a sulfonate group is preferred. The anionic polymer may contain only one anionic group or a plurality of anionic groups. Further, the cation of the anion group is not particularly limited, and examples thereof include a hydrogen ion and an alkali metal ion. Among them, from the viewpoint of less corrosion of equipment, alkali metal ions are preferred. The anionic polymer may contain only one pair of cations or a plurality of pairs of cations.

The anionic polymer used in the present invention may be a polymer composed only of a structural unit containing the above anionic group, or a polymer further containing a structural unit not containing the above anionic group. Further, the polymers are preferably crosslinkable. The anionic polymer may be composed of only one type of polymer, or may contain a plurality of anionic polymers. In addition, these anionic polymers and other polymers The mixture is fine. Here, the polymer other than the anionic polymer is preferably not a cationic polymer.

The anionic polymer is an anionic polymer having structural units of the following general formulae (9) and (10).

[wherein R ⁵ represents a hydrogen atom or a methyl group. G represents -SO ₃ H, -SO ₃ ^- M ⁺ , -PO ₃ H, -PO ₃ ^- M ⁺ , -CO ₂ H or -CO ₂ ^- M ⁺ . The M ⁺ system represents an ammonium ion or an alkali metal ion].

The anionic polymer containing a structural unit represented by the formula (9) is a homopolymer or a copolymer of 2-propenylamine-2-methylpropanesulfonic acid.

[wherein, R ⁵ represents a hydrogen atom or a methyl group, and T represents a phenyl or anthracene group in which a hydrogen atom may be substituted by a methyl group. The G system is synonymous with the formula (9)].

The anionic polymer containing a structural unit represented by the general formula (10) is exemplified by p-styrene sulfonate such as sodium p-styrenesulfonate. Homopolymer or copolymer, and the like.

Further, as the anionic polymer, a homopolymer or a copolymer of a sulfonic acid such as vinylsulfonic acid or (meth)acryl sulfonic acid or a salt thereof, fumaric acid or a maleic acid is also exemplified. A homopolymer or copolymer of a dicarboxylic acid such as diacid, methylene succinic acid, strontium maleate or strontium methylene succinate, a derivative thereof or a salt thereof.

In the formula (9) or (10), G is preferably a sulfonate group, a sulfonate group, a phosphonate group or a phosphonic acid group which provides a higher charge density. Further, in the general formulae (9) and (10), examples of the alkali metal ion represented by M ⁺ include sodium ions, potassium ions, lithium ions and the like.

In the present invention, the polymer composed of the monomer (A-2) having the above cation exchange group or anion exchange group may have a copolymer with the vinyl alcohol monomer (A-1) (A1). +A2) structure to constitute the ion exchanger (A), or (2) polymer (B-2) having the above cation exchange group or anion exchange group to form a mixture with the vinyl alcohol polymer (B-1) (B1+B2) constitutes an ion exchanger (A).

When having the above copolymer (A1+A2) structure, ethylene is contained in a mixture of a cationic group-containing vinyl alcohol polymer or a cationic group-containing vinyl alcohol polymer and a cationic group-free vinyl alcohol polymer. The ratio of the number of the alcohol units to the total number of the monomer units in the cationic polymer is preferably 50 mol% or more, more preferably 55 mol% or more. Here, the polymer other than the cationic polymer (the vinyl alcohol-based polymer not containing a cationic group) is preferably not an anionic polymer.

a vinyl alcohol polymer containing an anionic group, a vinyl alcohol polymer containing an anionic group, and a vinyl alcohol having no anionic group In the mixture of the polymers, the ratio of the number of vinyl alcohol units to the total number of monomer units in the anionic polymer is preferably 50 mol% or more, more preferably 55 mol% or more. Here, the polymer other than the anionic polymer (the vinyl alcohol polymer not containing an anion group) is preferably not a cationic polymer.

(copolymer of a monomer having a cationic group and a vinyl alcohol monomer)

In the case of a vinyl alcohol-based copolymer having a cationic group, a copolymer of a methacrylamide alkyl trialkylammonium salt and a vinyl alcohol component, a vinylbenzyltrioxane is particularly preferable from the viewpoint of easy availability. A copolymer of a quaternary ammonium salt and a vinyl alcohol component, a copolymer of a diallyldialkylammonium salt and a vinyl alcohol component.

(copolymer of an anion group monomer and a vinyl alcohol monomer)

In the case of a vinyl alcohol-based copolymer having an anionic group, a copolymer of a 2-propenylamine-2-methylpropanesulfonate component and a vinyl alcohol component, p-benzene is particularly preferable from the viewpoint of easy availability. a copolymer of a vinyl sulfonate component and a vinyl alcohol component.

(block copolymer)

In the present invention, an aspect of the ion exchanger (A) is composed of a copolymer containing a monomer unit having a cationic group or an anionic group and a vinyl alcohol monomer unit. Among them, a block copolymer containing the vinyl alcohol polymer component (a-1) and the polymer component (a-2) having a monomer unit having a cationic group or an anionic group is particularly preferably used. Thereby, the ionic polymer forms microphase separation, which can be suppressed by the degree of swelling of the film and shape retention. Both the functional vinyl alcohol polymer component and the polymer component formed by polymerizing the ion exchange unit responsible for the function of passing the cation or anion are responsible for the respective functions, so that the degree of swelling and dimensional stability of the ion exchange membrane can be achieved. The monomer unit having a cationic group or an anionic group is exemplified by the monomer units represented by the above formulas (1) to (10). Among them, from the viewpoint of easy availability, in terms of the cationic polymer, it is preferred to use a polymer component formed by polymerizing a methacrylamide alkyl trialkylammonium salt and a vinyl alcohol polymer. a block copolymer of a component, a block copolymer comprising a polymer component formed by polymerizing a vinylbenzyltrialkylammonium salt and a vinyl alcohol polymer component, or a diallyldialkyl group A block copolymer of a polymer component formed by polymerization of an ammonium salt and a vinyl alcohol polymer component. Further, as the anionic polymer, a block copolymer containing a polymer component formed by polymerizing a p-styrenesulfonate and a vinyl alcohol polymer component, or a 2-mer is preferably used. A block copolymer of a polymer component formed by polymerization of acrylamide-2-methylpropanesulfonate and a vinyl alcohol polymer component.

(ratio of vinyl alcohol monomer to ion exchange monomer in copolymer)

In the copolymer, the ratio of the vinyl alcohol monomer (A-1) to the ion exchange monomer (A-2) is preferably such that the vinyl alcohol monomer (A-1) is in the range of 99 mol% to 50 mol%. The ion-exchangeable monomer (A-2) is in the range of 1 mol% to 50 mol% (the total amount of the monomer (A-1) and the monomer (A-2) is 100 mol%). More preferably, the vinyl alcohol monomer (A-1) is in the range of 97 mol% to 60 mol%, and the ion exchange monomer (A-2) is 3 mol% to Within the range of 40 mol%.

If the ratio of the ion-exchangeable monomer is less than 1 mol%, the effective charge density of the ion-exchange layer is lowered, and the ion selectivity of the membrane is lowered. Further, when the ratio of the ion-exchangeable monomer exceeds 50 mol%, the degree of swelling of the ion-exchange layer increases, and the mechanical strength decreases.

(Manufacture of random copolymer)

The ion exchanger (A) containing a polymer having a cation exchange group or an anion exchange group (A1+A2) used in the ion exchange layer of the present invention can be obtained by using a cationic monomer or an anionic monomer with a vinyl ester. The monomer is copolymerized and then saponified by a usual method. The vinyl ester-based single system can be used as long as it can be radically polymerized. For example, vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl phthalate, vinyl laurate, vinyl stearate, vinyl benzoate, trimethyl vinyl acetate (for example) Vinyl pivalate) and versatic acid. Among them, vinyl acetate is preferred.

A method of copolymerizing a cationic monomer or an anionic monomer with a vinyl ester monomer may, for example, be a known method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method. Among these methods, a bulk polymerization method using no solvent or a solution polymerization method using a solvent such as an alcohol is usually employed. When the copolymerization reaction is carried out by a solution polymerization method, the alcohol to be used as the solvent may, for example, be a lower alcohol such as methanol, ethanol or propanol. Examples of the initiator used in the copolymerization reaction include 2,2'-azobis(2,4-dimethyl-pentanenitrile) and 1,1'-azobis(cyclohexane- Azo-based initiator such as 1,1-azobis(cyclohexane-1-carbonitrile) or 2,2'-azobis(N-butyl-2-methylpropionamide) A well-known initiator such as a benzoyl sulfonium group or a peroxide-based initiator such as n-propyl peroxycarbonic acid. The polymerization temperature at the time of carrying out the copolymerization reaction is not particularly limited, but is preferably in the range of 5 ° C to 180 ° C.

The vinyl ester polymer obtained by copolymerizing a cationic monomer or an anionic monomer and a vinyl ester monomer is saponified in a solvent according to a known method, whereby a cationic group or An anionic vinyl alcohol polymer.

In the catalyst for the saponification reaction of the vinyl ester polymer, a basic substance is usually used, and examples thereof include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, and alkali metal alkoxides such as sodium methoxide. (alkoxide). The saponification catalyst may be added all at once in the initial stage of the saponification reaction, or a part may be added at the beginning of the saponification reaction, and the remainder may be added during the saponification reaction. The solvent used for the saponification reaction may, for example, be methanol, methyl acetate, dimethyl hydrazine or dimethylformamide. Among them, methanol is preferred. The saponification reaction can be carried out by any one of a batch method and a continuous method. After the completion of the saponification reaction, the remaining saponification catalyst may be neutralized, and the neutralizing agent which can be used may, for example, be an organic acid such as acetic acid or lactic acid or an ester compound such as methyl acetate.

The degree of saponification of the ionic group-containing vinyl alcohol polymer is not particularly limited, but is preferably from 40 mol% to 99.9 mol%. When the degree of saponification is less than 40 mol%, the crystallinity is lowered, and the durability of the ion exchanger is insufficient. The degree of saponification is more preferably 60 mol% or more, and still more preferably 80 mol% or more. Usually, the degree of saponification is 99.9 mol% or less. In this case, the degree of saponification when the vinyl alcohol polymer is a mixture of a plurality of vinyl alcohol polymers is in compliance with JIS K6726 measured value. The degree of saponification of the vinyl alcohol-based polymer not containing an ionic group used in the present invention is also preferably in the above range.

The viscosity average degree of polymerization (hereinafter sometimes referred to simply as the degree of polymerization) of the ionic group-containing vinyl alcohol polymer is not particularly limited, but is preferably from 50 to 10,000. If the degree of polymerization is less than 50, practically, the ion exchanger cannot maintain sufficient durability. The degree of polymerization is more preferably 100 or more. If the degree of polymerization exceeds 10,000, the viscosity is too high when it is prepared into an aqueous solution, which is inconvenient to use. The degree of polymerization is preferably 8,000 or less. In this case, the degree of polymerization when the vinyl alcohol polymer is a mixture of a plurality of vinyl alcohol polymers is referred to as the average degree of polymerization of the entire mixture. Further, the viscosity average degree of polymerization of the above vinyl alcohol-based polymer is a value measured in accordance with the amount of JIS K6726. The degree of polymerization of the vinyl alcohol-based polymer not containing an ionic group used in the present invention is also preferably in the above range.

(Manufacture of block copolymer)

The method for producing a polymer in which a polymer component formed by polymerizing a cation-exchangeable monomer or an anion-exchangeable monomer and a vinyl alcohol-based polymer component are block-copolymerized, which is used in the present invention, is mainly classified into the following two types. method. That is, (1) a method of bonding a cationic group or an anionic group to a specific block after producing a desired block copolymer, and (2) reacting in the presence of a vinyl alcohol-based polymer A method of obtaining a desired block copolymer by polymerizing at least one cationic monomer or anionic monomer at the terminal. In view of the ease of industrial production, in the method of (1), it is preferred that one or a plurality of monomers are subjected to block copolymerization in the presence of a vinyl alcohol polymer having a mercapto group at the terminal. Then guided in one or more polymer components in the block copolymer a method of introducing a cationic group or an anionic group; and for the method of (2), preferably at least one cationic monomer or anionic monomer is subjected to radical polymerization in the presence of a vinyl alcohol-based polymer having a mercapto group at the terminal The method by which the block copolymer is produced. In particular, from the viewpoint of being able to easily control the kind and amount of each component in the block copolymer, it is particularly preferred to use at least one cationic monomer or anion in the presence of a vinyl alcohol polymer having a mercapto group at the terminal. A method in which a monomer is subjected to radical polymerization to produce a block copolymer.

The vinyl alcohol-based polymer having a mercapto group at the terminal used for the production of the block copolymer can be obtained, for example, by the method described in JP-A-59-187003. In other words, a method in which a vinyl ester monomer, for example, vinyl acetate, is subjected to radical polymerization in the presence of a thiolic acid to obtain a vinyl ester polymer, followed by saponification. In addition, a method of obtaining a block copolymer by using a vinyl alcohol-based polymer having a mercapto group at the terminal and an ionic monomer, for example, a method described in, for example, JP-A-59-189113. That is, the block copolymer can be obtained by radical polymerization of an ionic monomer in the presence of a vinyl alcohol-based polymer having a mercapto group at the terminal. The radical polymerization can be carried out by a known method such as bulk polymerization, solution polymerization, bead polymerization, emulsion polymerization, or the like, and is preferably a solvent capable of dissolving a vinyl alcohol polymer having a mercapto group at the terminal, for example, water. It is carried out in a solvent mainly composed of dimethyl hydrazine. Further, as far as the polymerization process is concerned, any one of a batch method, a semi-batch method, and a continuous method can be employed.

(Manufacture of graft copolymer)

The ion exchanger (A) containing a polymer having a cation exchange group or an anion exchange group used in the ion exchange layer of the present invention is obtained by, for example, copolymerizing a monomer having a mercapto group in a side chain with a vinyl ester monomer. The side chain contains a mercapto group-based vinyl ester polymer. The vinyl ester-based single system can be used as long as it can carry out radical polymerization. For example, vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl phthalate, vinyl laurate, vinyl stearate, vinyl benzoate, trimethyl vinyl acetate and Tert-ethylene carbonate and the like. Among them, vinyl acetate is preferred.

Next, the obtained vinyl ester-based polymer having a mercapto group in the side chain is formed into a vinyl alcohol-based polymer having a mercapto group in a side chain by the above-described saponification method, and then the method described in the item of the above-mentioned block copolymer is used. The cation exchange group or the anion exchange group is introduced, and finally, a vinyl alcohol polymer having an ion exchange group introduced into the side chain can be obtained.

(Method for Producing Polymer B-2 Having Ion Exchange Group)

In the present invention, when the ion exchanger is a mixture of a vinyl alcohol polymer (B-1) and a polymer (B-2) having an ion exchange group, the polymer (B-2) having an ion exchange group is used. The method for producing the polymer (having a cationic monomer or an anionic monomer) may be a known method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method. Among these methods, a bulk polymerization method using no solvent or a solution polymerization method using a solvent such as an alcohol is usually employed. When the polymerization reaction is carried out by a solution polymerization method, the alcohol to be used as the solvent may, for example, be a lower alcohol such as methanol, ethanol or propanol. For the initiator used in the polymerization, 2,2'-azobis(2,4-dimethyl-pentanenitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azo double Well-known initiators such as azo-based initiators such as (N-butyl-2-methylpropionamide), peroxide-based initiators such as benzoyl peroxide and n-propyl peroxycarbonate . The polymerization temperature at the time of carrying out the polymerization reaction is not particularly limited, but is preferably in the range of 5 ° C to 180 ° C.

The polymer having an ion-exchange group used in the present invention may be a homopolymer of the above-mentioned cationic monomer or anionic monomer, or may be a copolymerization of two or more kinds of cationic monomers. Two or more kinds of anionic monomers may be copolymerized.

(About vinyl alcohol polymer)

In the present invention, the vinyl alcohol polymer (B-1) used when the ion exchanger is a mixture of the vinyl alcohol polymer (B-1) and the polymer (B-2) having an ion exchange group Can be manufactured as follows. Examples of the vinyl ester monomer used for the production of the vinyl alcohol polymer include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl phthalate, and vinyl laurate. Vinyl stearate, vinyl benzoate, trimethyl vinyl acetate and vinyl versatate are preferred, especially vinyl acetate.

Further, the vinyl alcohol polymer of the present invention can also polymerize a vinyl ester monomer by the presence of a thiol compound such as 2-indole ethanol, n-dodecyl mercaptan, thioglycolic acid or 3-mercaptopropionic acid. A polyvinyl ester is obtained and then saponified to produce.

Examples of the method of polymerizing the vinyl ester monomer include known methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. In these methods, usually no solvent is used. The bulk polymerization method carried out or a solution polymerization method using a solvent such as an alcohol. From the viewpoint of improving the effects of the present invention, it is preferred to use a solution polymerization method in which polymerization is carried out together with a lower alcohol. The lower alcohol is not particularly limited, but is preferably an alcohol having 3 or less carbon atoms such as methanol, ethanol, propanol or isopropanol, and methanol is usually used. When the polymerization is carried out by a bulk polymerization method or a solution polymerization method, the reaction can be carried out by any one of a batch type and a continuous type. Examples of the initiator used in the polymerization reaction include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethyl-pentanenitrile), and 2, An azo initiator such as 2'-azobis(4-methoxy-2,4-dimethylvaleronitrile); an organic peroxide such as benzammonium peroxide or n-propyl peroxycarbonate It is a well-known starter which does not impair the effect of the present invention, such as an initiator. Among them, an organic peroxide-based initiator having a half-life of from 10 minutes to 110 minutes at 60 ° C is preferred, and peroxydicarbonic acid is particularly preferred. The polymerization temperature at the time of carrying out the polymerization reaction is not particularly limited, but is preferably in the range of 5 ° C to 200 ° C.

When the vinyl ester monomer is subjected to radical polymerization, the monomer capable of copolymerization can be copolymerized as needed, as long as the effects of the present invention are not impaired. Examples of such a monomer include α-olefins such as ethylene, propylene, 1-butene, isobutylene, and 1-hexene; fumaric acid, maleic acid, and methylene succinic acid; a carboxylic acid such as bismuth maleate or sulfonium methylene succinate or a derivative thereof; an acrylate such as acrylic acid or a salt thereof, methyl acrylate, ethyl acrylate, n-propyl acrylate or isopropyl acrylate; A methacrylate such as acrylic acid or a salt thereof, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate or isopropyl methacrylate; acrylamide, N-methyl acrylamide, N- Ethyl propylene Acrylamide derivatives such as decylamine; methacrylamide derivatives such as methacrylamide, N-methyl methacrylamide, N-ethyl methacrylamide; methyl vinyl ether, ethyl Vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether and other vinyl ether; ethylene glycol ether, 1,3-propanediol vinyl ether, 1,4-butanediol vinyl ether, etc. Vinyl ether; allyl ether such as allyl acetate, propyl allyl ether, butyl allyl ether, hexyl allyl ether; monomer having an oxygen alkyl group; isopropenyl acetate, 3-butene-1 - alcohol, 4-penten-1-ol, 5-hexen-1-ol, 7-octene-1-ol, 9-nonen-1-ol, 3-methyl-3-butene-1 a hydroxy group-containing α-olefin such as an alcohol; a sulfonic acid group such as ethyl sulfonate, allyl sulfonic acid, methallyl sulfonic acid or 2-propenylamine-2-methylpropane sulfonic acid; Ethyloxyethyltrimethylammonium chloride, ethyleneoxybutyltrimethylammonium chloride, ethyleneoxyethyldimethylamine, vinyloxymethyldiethylamine, N-acrylamide Trimethylammonium chloride, N-propyleneamine ethyltrimethylammonium chloride, N-propyleneamine dimethylamine, allylic a monomer having a cationic group such as trimethylammonium chloride, methallyltrimethylammonium chloride, dimethylpropenylamine or allylethylamine; vinyltrimethoxydecane, vinylmethyldi Methoxydecane, vinyl dimethyl methoxy decane, vinyl triethoxy decane, vinyl methyl diethoxy decane, vinyl dimethyl ethoxy decane, 3- (meth) propylene A monomer having an alkylene group such as guanamine-propyltrimethoxydecane or 3-(meth)acrylamide-propyltriethoxysilane. The amount of the monomer which can be copolymerized with the vinyl ester monomer varies depending on the purpose of use, use, etc., and is usually 20 mol% or less based on the total amount of the monomers used for the copolymerization. It is 10 mol% or less.

(Polyvinyl alcohol-based polymer and polymerization containing ion exchange groups Ratio of things)

In the present invention, the ratio of the vinyl alcohol-based polymer (B-1) to the polymer (B-2) having an ion-exchange group is preferably from 99 mol% to 50 mol% of the vinyl alcohol-based polymer (B-1). The polymer (B-2) having an ion exchange group in the range is in the range of 1 mol% to 50 mol%. More preferably, the vinyl alcohol-based polymer (B-1) is in the range of from 97 mol% to 60 mol%, and the polymer (B-2) having an ion-exchange group is in the range of from 3 mol% to 40 mol%.

If the ratio of the polymer having an ion exchange group is less than 1 mol%, the effective charge density of the ion exchange layer is low, and the ion selectivity of the film is deteriorated. Further, if the ratio of the polymer having an ion-exchange group exceeds 50 mol%, the degree of swelling of the ion-exchange layer may increase, and the mechanical strength may deteriorate and the film may swell.

(porous electrode layer)

As the carbon material contained in the porous electrode layer, activated carbon, carbon black or the like is used, and in particular, activated carbon is preferably used. The shape of the activated carbon can be arbitrarily selected, and examples thereof include a powder form, a particle form, and a fiber form. Among the activated carbons, it is preferred to use a high specific surface area activated carbon from the viewpoint of a large amount of adsorption of ions. The BET specific surface area of the high specific surface area activated carbon is preferably 700 m ² /g or more, more preferably 1000 m ² /g or more, and still more preferably 1500 m ² /g or more.

The content of the carbon material in the porous electrode layer is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more. When the content of the carbon material is less than 70% by mass, the amount of adsorption of ions is insufficient.

Porous as long as it does not hinder the effects of the present invention The mass electrode layer may also contain various additives. Examples of the additive include a binder, a conductive agent, a dispersant, and a tackifier. The content of the additive contained in the porous electrode layer is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass or less.

The conductivity of the porous electrode layer may be appropriately adjusted depending on the use of the electrode, and the carbon material can be adjusted by using a conductive carbon material and containing a conductive agent.

(collector layer)

The current collector layer used in the electrode of the present invention is not particularly limited as long as it has high conductivity and corrosion resistance, and examples thereof include a sheet of graphite and a metal such as titanium, gold, platinum, or a composite material of these materials. Foil, etc. Among them, in view of the excellent balance between corrosion resistance and electrical conductivity, graphite flakes are particularly preferred. The thickness of the current collector layer is not particularly limited, but is preferably 5 μm to 5000 μm, more preferably 10 μm to 3000 μm.

In the electrode of the present invention, as long as the charge is transferred between the current collector layer and the porous electrode layer efficiently, the movement of ions between the porous electrode layer and the outside of the electrode is mostly carried out via the ion exchange layer, and The porous electrode layer has a surface area capable of adsorbing a predetermined amount of ions, and the size of each layer is not particularly limited, and may be appropriately adjusted depending on the use of the electrode. Further, the electrode of the present invention may have a layer other than the current collector layer, the porous electrode layer, and the ion exchange layer, within a range that does not impair the effects of the present invention.

In the electrode system of the present invention, it is preferred to form a porous electrode layer directly on the surface of the current collector layer, form an ion exchange layer on the surface of the porous electrode layer, or impregnate the ion exchange layer in the porous electrode layer. Ion exchange layer The vinyl alcohol-based polymer contained has a high affinity for the porous electrode layer, so that high adhesion is exhibited between the two layers. Therefore, not only the interface resistance between the ion exchange layer and the porous electrode layer but also the peeling between the two layers can be suppressed.

From the viewpoint of excellent organic contamination resistance, in the electrode of the present invention, it is preferred to arrange an ion exchange layer containing a vinyl alcohol polymer on the outermost surface.

(additive)

The ion exchange membrane used in the electrode of the present invention may contain various additives such as an antifoaming agent and an inorganic filler insofar as the object of the present invention is not impaired.

(Method of manufacturing the electrode)

The method for producing the electrode of the present invention is not particularly limited, but is preferably a method in which a slurry containing a carbon material and a solution containing an ion exchanger are simultaneously or separately applied to the surface of the current collector layer to form a coating film. The mixture is dried to crosslink the ion exchanger, thereby forming a layer of the porous electrode layer and the ion exchange layer. According to the above method, an electrode in which the current collector layer, the porous electrode layer, and the ion exchange layer are integrated can be obtained. In the above production method, since the applied slurry and the solution are simultaneously dried, not only the ion exchange layer defects formed but also the adhesion between the porous electrode layer and the ion exchange layer are further improved.

The dispersion medium in the slurry is not particularly limited as long as it can disperse the raw material of the porous electrode layer such as a carbon material, and examples thereof include water, an organic solvent, and a mixture thereof. The composition of the dispersed material may be appropriately adjusted in accordance with the composition of the porous electrode layer to be formed. The content of the dispersion material in the slurry is not particularly limited, but is usually 10% by mass to 60% by mass.

In the above production method, (1) a solution containing a vinyl alcohol-based copolymer into which an ion-exchange group is introduced or (2) a solvent in a solution containing a polymer having an ion-exchange group and a vinyl alcohol-based polymer, as long as The polymer is not particularly limited, and examples thereof include water, an organic solvent, and a mixture thereof. The composition of the solute may be appropriately adjusted in accordance with the composition of the porous electrode layer to be formed. The content of the solute in the above solution is not particularly limited, and is usually from 5% by mass to 30% by mass.

(coating)

The coating device used when applying the slurry and the solution is not particularly limited, and a known coating device can be used. For example, a curtain coating apparatus, a squeeze coating apparatus, and a slide coating apparatus are mentioned. When the slurry and the solution are simultaneously applied, the slurry and the solution may be applied by a single coating operation, or the slurry may be mixed with the solution in advance and applied to the surface of the current collector layer. Further, when the slurry and the solution are separately applied, the same coating method may be employed, or coating may be carried out by a different coating method. Specific coating methods include roll coating, comma coating, kiss coating, gravure coating, and slide bead coating.

The porous electrode layer containing a carbon material of the electrode of the present invention from the viewpoints of ensuring the amount of ion adsorption, coating film strength, other properties, and handling ability necessary for use as an electrode for a liquid-pass type capacitor The thickness is preferably from 50 μm to 1000 μm. Porous electricity When the thickness of the electrode layer is less than 50 μm, the adsorption capacity of ions becomes insufficient. On the other hand, when the thickness of the porous electrode layer exceeds 1000 μm, the porous electrode layer becomes brittle and defects such as cracks are likely to occur. The thickness of the porous electrode layer is more preferably from 100 μm to 800 μm, still more preferably from 150 μm to 500 μm. Further, the thickness of the porous electrode layer means the thickness of the dried porous electrode layer.

The thickness of the ion exchange layer of the electrode of the present invention is preferably 70 μm or less from the viewpoint of ensuring ion permeability, other properties, surface coverage, and the like which are necessary for use as an electrode for a liquid-pass type capacitor. When the thickness exceeds 70 μm, the ion penetration resistance becomes large. The thickness of the ion exchange layer is more preferably 50 μm or less, and still more preferably 30 μm. Further, the thickness of the ion exchange layer is the thickness of the dried ion exchange layer. Further, regarding the thickness at the time of impregnation of the ion-exchange layer, the range of the resin can be found from the cross-sectional SEM image, and the range is the thickness.

(heat treatment)

In the above production method, it is preferred to further heat-treat after drying the coating film. By heat-treating the coating film, crystallization of (1) the vinyl alcohol-based copolymer into which the ion-exchange group is introduced or (2) the vinyl alcohol-based copolymer in the mixture is promoted, and the mechanical strength of the ion-exchange layer is further improved. The method of the heat treatment is not particularly limited, and a hot air dryer or the like is generally used. The temperature of the heat treatment is not particularly limited, but is preferably from 100 ° C to 250 ° C. When the heat treatment temperature is less than 100 ° C, the crystallization of the vinyl alcohol polymer into which the ion exchange group is introduced is not promoted, and the effect of improving the mechanical strength cannot be obtained. Conversely, when it is treated at 250 ° C or higher, (1) a vinyl alcohol-based polymer into which an ion exchange group is introduced or (2) a mixture The vinyl alcohol polymer has melting and decomposing. More preferably, it is heat-treated at 120 ° C or more and 200 ° C or less.

(cross-linking processing)

In the present invention, it is necessary to contain the vinyl alcohol monomer (A-1) and the ion exchange monomer (A-2) so that the ion exchanger (A) has a degree of crosslinking of 4.30 or less. An ion exchanger of a copolymer (A1+A2) or a mixture of a vinyl alcohol polymer (B-1) and a polymer (B-2) having an ion exchange group (B1+B2) to form an acetal cross The cross-linking agent is cross-linked to introduce a cross-linking bond. Therefore, after the ion exchange coating film described above is dried, a crosslinking treatment is performed to introduce a crosslinked bond. Under the measurement of the measurement method shown in the examples described later, the degree of cross-linking of the introduced cross-linking must be formed to be 4.30 or less. The adjustment to form the cross-linking degree to 4.30 or less can be carried out by selecting reaction conditions such as the crosslinking reaction time and the pH of the reaction liquid. By the introduction of the cross-linking bond, the swelling of the obtained ion exchanger is suppressed, a stable high current density is achieved, the ion exchange performance is improved, and the mechanical strength and durability of the ion exchanger are also improved.

The method of the crosslinking treatment is not particularly limited as long as it is a method in which molecular bonds of the polymer can be bonded to each other by an acetal bond. A method of immersing an ion exchanger in a solution containing a crosslinking treatment agent which produces cross-linking of acetal, or the like is usually used. Examples of the crosslinking treatment agent include glutaraldehyde, formaldehyde, glyoxal, benzaldehyde, succinaldehyde, malondialdehyde, adipaldehyde, terephthalaldehyde, and nonanedial. Among them, glutaraldehyde, formaldehyde, glyoxal, etc. are preferred, and dialdehydes such as glutaraldehyde and glyoxal are particularly preferred.

From the viewpoint of the stability of the crosslinked structure, glutaraldehyde is particularly preferred. Regarding the concentration of the crosslinking treatment agent, the volume concentration of the crosslinking treatment agent is usually from 0.001% by volume to 1% by volume of the solution.

In the above production method, the crosslinking treatment may be carried out without performing heat treatment, but it is preferred to carry out the crosslinking treatment after the heat treatment or the hot pressing treatment. The portion which is not easily crosslinked is formed by heat treatment or hot pressing treatment, and then the crosslinking portion and the uncrosslinked portion are mixed by the crosslinking treatment, whereby the film strength is improved. From the viewpoint of the mechanical strength of the obtained ion exchange layer, it is particularly preferable to carry out the steps of hot pressing treatment, heat treatment, and crosslinking treatment. Further, when the ion exchanger is a water-soluble polymer, the crosslinking treatment is carried out after the heat treatment and the hot press treatment, and the occurrence of elution can be prevented.

(liquid-through capacitor)

As described above, the electrode system of the present invention can efficiently and stably perform adsorption and desorption of ions for a long period of time. Therefore, the electrode system can be suitably used as an electrode for a liquid-pass type capacitor or the like.

Hereinafter, a liquid-through type capacitor using the electrode which is a preferred embodiment of the electrode of the present invention will be described as an example, and adsorption and desorption of ions by the electrode will be described. Fig. 1 is a view showing an example of a state in which ions are adsorbed by the liquid-pass type capacitor 1 using the electrode 2 and the electrode 3 of the present invention.

The electrode 2 has an anion exchange layer 4 containing a vinyl alcohol polymer having a cation exchange group introduced therein as an ion exchange layer, and the current collector layer 6, the porous electrode layer 5, and the anion exchange layer 4 are arranged in this order. Electrode 3 has a vinyl alcohol polymerization containing an anion exchange group introduced therein The cation exchange layer 7 of the material is configured by arranging the current collector layer 9, the porous electrode layer 8, and the cation exchange layer 7 as an ion exchange layer. In the liquid-pass type capacitor 1 , the flow path portion 10 is disposed between the electrode 2 and the electrode 3, and the anion exchange layer 4 and the cation exchange layer 7 are disposed to face each other with the flow path portion 10 interposed therebetween.

In the liquid-pass type capacitor 1, the flow path portion 10 can be formed by a method of disposing a separator layer between the anion exchange layer 4 and the cation exchange layer 7. The material of the separator used for the formation of the flow path portion 10 is not particularly limited as long as it is electrically insulating and allows the liquid to pass therethrough, and examples thereof include a fiber sheet such as paper, woven cloth, and non-woven fabric, a resin foam sheet, and a resin. Net and so on. The distance between the electrodes set depending on the thickness of the flow path portion 10 is usually 50 μm to 1000 μm.

In the liquid-pass type capacitor 1, since the anion exchange layer 4 and the cation exchange layer 7 are opposed to each other via the flow path portion 10, most of the movement of the anion 11 between the porous electrode layer 5 and the flow path portion 10 is via The anion exchange layer 4 is carried out, and most of the movement of the cation 12 between the porous electrode layer 8 and the flow path portion 10 is performed via the cation exchange layer 7.

When the adsorption of ions in the liquid supplied to the flow path portion 10 is performed, the voltage is applied such that the fixed charge of the ion exchange layer in each electrode and the charge supplied to the porous electrode layer have the same polarity symbol. Between the electrode 2 and the electrode 3. That is, a positive charge is supplied to the porous electrode layer 5, and a negative charge is supplied to the porous electrode layer 8, respectively. The anion 11 in the flow path portion 10 moves into the electrode 2 through the anion exchange layer 4, and is adsorbed by the porous electrode layer 5 having a positive charge. On the other hand, the cation 12 in the flow path portion 10 is moved to the electrode 3 through the cation exchange layer 7. Inside, it is adsorbed by the negatively charged porous electrode layer 8.

When the ions are adsorbed, even if the cation 13 is present in the porous electrode layer 5 of the electrode 2, the cation 13 hardly leaks into the flow path portion 10 because it is difficult to pass through the anion exchange layer 4. Further, even if an anion 14 is present in the porous electrode layer 8 of the electrode 3, the anion 14 hardly leaks to the flow path portion 10 because it is difficult to pass through the cation exchange layer 7. Therefore, there is almost no leakage of ions inside the electrode 2 and the electrode 3 into the flow path portion 10 to contaminate the liquid supplied into the flow path portion 10.

Fig. 2 is a view showing an example of a state in which ions are removed by the liquid-passing capacitor 1 using the electrode 2 and the electrode 3 of the present invention. The desorption of ions adsorbed by the porous electrode layer 5 and the porous electrode layer 8 can be performed by supplying the charges opposite to the polarity sign at the time of adsorption to the porous electrode layer 5 and the porous electrode layer 8. At this time, the anion 11 desorbed from the porous electrode layer 5 moves to the channel portion 10 through the anion exchange layer 4, but hardly moves to the electrode 3 on which the cation exchange layer 7 is disposed, and is adsorbed again by the porous electrode layer 8. . Further, the cation 12 desorbed from the porous electrode layer 8 moves to the channel portion 10 through the cation exchange layer 7, but hardly moves to the electrode 2 in which the anion exchange layer 4 is disposed, and is adsorbed by the porous electrode layer 5 again. . Therefore, the next time the adsorption of ions is performed, there is almost no decrease in the adsorption efficiency due to the re-adsorbed ions.

The liquid-pass capacitor 1 of the present invention may be formed by laminating a capacitor unit in which the flow path portion 10 is disposed between the electrode 2 having the anion exchange layer 4 and the electrode 3 having the cation exchange layer 7. When the capacitor unit is laminated, it is preferably fixed by an ion exchange layer. The collector layers of the electrodes having the same polarity symbol are laminated in such a manner as to face each other. In addition, the liquid-pass type capacitor formed by laminating a plurality of the capacitor units can be formed by arranging the electrodes formed on the both sides of the current collector layer with the porous electrode layer and the ion exchange layer, respectively, via the flow path portion. Laminated to make.

As described above, the electrode system of the present invention can efficiently and stably perform adsorption and desorption of ions for a long period of time. Therefore, by using the liquid-pass type capacitor of the above-described electrode, it is possible to carry out desalination, separation of an ionic substance and a nonionic substance, and the like with high efficiency and stability for a long period of time.

(desalting device)

Fig. 3 is a schematic view showing an example of a desalination device 15 having the liquid-through capacitor 1 of the present invention, and Fig. 4 is an exploded perspective view of the liquid-through capacitor 1 in the desalination device 15. The desalination device 15 includes a liquid-passing capacitor 1, a container 16 accommodating the liquid-passing capacitor 1, and a DC power source 17, and the positive electrode and the negative electrode of the DC power source 17 are connected to the electrode 2 and the electrode 3 so as to be exchangeable, respectively. The container 16 has a supply port 18 for a liquid containing an ionic substance to be desalted by the liquid-through capacitor 1, and a discharge port 19 for the desalted liquid.

The liquid-pass type capacitor 1 in the desalination device 15 is formed by laminating the capacitor unit 20 in which the flow path portion 10 is disposed between the electrode 2 having the anion exchange layer 4 and the electrode 3 having the cation exchange layer 7. At this time, it is preferable that the current collector layers 5 of the electrodes 2 face each other and the current collector layers 8 of the electrodes 3 face each other.

In the liquid-pass type capacitor 1, a through hole is formed in the vicinity of the electrode other than the electrode at the end of the supply port 18 side and the center of the flow path portion 10. 21, the through hole 21 on the side of the discharge port 19 is connected to the discharge port 19. The liquid system supplied from the supply port 18 into the container 16 is introduced into the flow path portion 10 from the periphery of the flow path portion 10, is desalted in the flow path portion 10, and is discharged from the discharge port 19 through the through hole 21. The arrows in Figures 3 and 4 indicate the flow of liquid. In the desalination apparatus 15 shown in Fig. 3, the supplied liquid system is discharged through the primary flow path portion 10, but the desalination device 15 may be formed to be discharged after passing through the plurality of flow path portions 10.

(desalting method)

The desalination method using the desalination device 15 will be described. When the desalination device 15 is used for desalination, it is preferably carried out by a method comprising the following steps: in the first step, the electrode 2 having the anion exchange layer 4 is used as a positive electrode, and the electrode 3 having the cation exchange layer 7 is used as a negative electrode. The DC power source 17 applies a voltage to each of the electrodes, and supplies a liquid containing an ionic substance to the flow path portion 10 between the electrode 2 and the electrode 3 to which the voltage is applied, and the ions in the liquid are made of the porous electrode layer 5 and the porous electrode. After the layer 8 is adsorbed, the liquid is discharged and recovered; and in the second step, the liquid is supplied to the flow path portion 10, the electrode 2 having the anion exchange layer 4 is a negative electrode, and the electrode 3 having the cation exchange layer 7 is a positive electrode. By applying a voltage to the electrode 2 and the electrode 3 by the DC power source 17, the ions adsorbed by the porous electrode layer 5 and the porous electrode layer 8 in the first step are desorbed, and the liquid containing the desorbed ions is discharged.

In the first step, the desalting of the liquid containing the ionic substance and the recovery of the desalting liquid are performed. The electrode 2 is connected to the positive electrode of the DC power source 17, and the electrode 3 is connected to the negative electrode of the DC power source 17. The desalted liquid system containing the ionic substance is supplied to the supply port 18. After the supply, the liquid system is It is introduced into the flow path portion 10, and ions from the ionic substance in the liquid are adsorbed by the electrode 2 to which the voltage is applied and the porous electrode layer 5 and the porous electrode 8 in the electrode 3. The adsorption time at this time is appropriately adjusted depending on the target concentration of the ionic substance or the like. The voltage applied between the electrode 2 and the electrode 3 is not particularly limited, but is preferably 0.5 V to 3 V. The desalting system is recovered from the discharge port 19.

In the second step, the ions adsorbed by the porous electrode layer 5 and the porous electrode layer 8 in the first step are desorbed, whereby the electrode 2 and the electrode 3 are washed. The cleaning liquid is supplied to the flow path unit 10, the electrode 2 is connected to the negative electrode of the DC power source 17, and the electrode 3 is connected to the positive electrode to desorb the adsorbed ions. The voltage applied to the electrode 2 and the electrode 3 and the desorption time are not particularly limited. The voltage applied between the electrode 2 and the electrode 3 is usually 0.5 V to 3 V. The desorbed ions move into the liquid in the flow path portion 10. The cleaning liquid containing desorbed ions is discharged from the discharge port 19. The desalination apparatus 15 after washing the electrode 2 and the electrode 3 as described above can be reused for desalting (first step). When the electrode is contaminated by desalting or the like for a long period of time, the electrode may be washed with an alkaline cleaning solution or the like. Since the electrode system of the present invention has excellent alkali resistance, even if such a cleaning method is carried out, the electrode is hardly adversely affected.

[Examples]

Hereinafter, the present invention will be described in further detail by way of examples, but the present invention is not limited by the following examples. In addition, in the following examples and comparative examples, "%" and "parts" are quality standards unless otherwise specified. The analysis and evaluation in the examples and comparative examples were carried out in the following manner.

1) Evaluation method of ratio of ion exchange unit contained in ion exchanger (A)

The vinyl alcohol-based polymer containing the ion exchange unit obtained by polymerization was dissolved in a deuterated solvent (concentration: 5 wt%), and measured under the following NMR apparatus and conditions. The ratio of the ion exchange unit contained in the polymer obtained by polymerization is calculated from the peak intensity of the unit having an ion exchange group and the peak intensity of the vinyl alcohol polymer. The ion exchange unit used in the following examples has a benzene ring, and therefore a methine proton based on a peak of a benzene ring appearing at 6.0 ppm to 8.0 ppm and a vinyl alcohol polymer present at around 4.0 ppm. The ratio is calculated as the ratio of the ion exchange unit.

Device name: Japanese electronic superconducting nuclear magnetic resonance device Lambda 500

Observation frequency: 500MHz (1H)

Solvent: heavy water

Polymer concentration: 5 wt% (H-NMR)

Measurement temperature: 80 ° C (H-NMR)

Cumulative number: 256 times (H-NMR)

Pulse repetition time: 4 seconds (H-NMR)

Sample rotation speed: 10Hz~12Hz

The evaluation of the electrode composed of the current collector, the porous electrode layer, and the ion exchange layer produced was measured by the following method.

2) Thickness measurement (porous electrode layer and ion exchange layer)

The integrated electrode thus produced was measured for the thickness of the entire electrode of the current collector layer/porous electrode layer/ion exchange layer by a DIGIMATIC micrometer manufactured by Mitutoyo Co., Ltd. Formed on the electrode table The thickness of the ion exchange layer of the surface was observed and evaluated by a scanning electron microscope "S-3000" (manufactured by Hitachi, Ltd.). Further, the current collecting system measures the thickness in advance using a DIGIMATIC micrometer, and then subtracts the thickness of the ion exchange layer to calculate the thickness of the remaining porous electrode layer. Further, the value of the thickness obtained here is a value at the time of drying.

3) Evaluation of the degree of crosslinking of ion exchangers on the electrode surface

The degree of crosslinking of the obtained ion exchanger was calculated by the total reflection method (ATR method) of infrared spectroscopy (FT-IR). The sample size was 2 cm × 3 cm, and the degree of crosslinking of the electrode surface was calculated using an infrared spectrophotometer JIR-5500 manufactured by JEOL. In the vicinity of 2920cm ^-1 (2770cm ^-1 to 2995cm ^-1) peak (peak due to the CH stretching modes bonded) as the reference peak area (I ₁₎ area, to the vicinity of 3380cm ^{-1 (2995cm -1} to The area of the peak (from the peak of the OH group) of 3755 cm ^-1 ) is taken as the area of the target peak (I ₂ ), and I ₂ /I ₁ indicating the ratio of the two is used as the degree of crosslinking of the ion exchanger.

4) Measurement of electrode resistance

Fig. 5 is a schematic view showing the apparatus used for the measurement of the electrode resistance in the embodiment. As shown in Fig. 5, a circular electrode 23 cut into a diameter of 12 mm and a circular separator 24 cut into a diameter of 16 mm are sequentially disposed between the cylindrical titanium electrodes 22 having a diameter of 20 mm and a height of 10 mm (Japanese special "LS60" manufactured by Kyocera Co., Ltd., having a thickness of 90 μm), was cut into a circular electrode 23 having a diameter of 12 mm. At this time, in the state where the ^two electrodes are pressurized to the titanium electrode 22 at a pressure of 1 kg/cm ² to 2 kg/cm ² in the current collector layer, a Potentiostat/Galvanostat VSP manufactured by BioLogic Co., Ltd. is used. The impedance is measured in the range of 8 mHz to 1 MHz, and the real resistance at a frequency of 1 Hz is used as the impedance resistance, and the impedance resistance is used as the electrode resistance.

5) Evaluation of durability of the electrode by water immersion test

The obtained electrode was immersed in water at 23 ° C, and durability evaluation was performed by a water immersion test. The surface portion of the electrode after 2 weeks was visually observed, and the durability of the electrode was evaluated according to the state of the electrode surface by the following determination method.

A: There is no change in the surface of the electrode, and the appearance is maintained in a good state.

B: A part of the electrode end was peeled off, or a part of the electrode was found to be uneven by the surface of the electrode (the area on the surface of the electrode was 1/3 or less).

C: Since the surface of the electrode is swollen to form severe irregularities, peeling phenomenon can be found on the interface of the electrode (concavity and convexity is found in an area of 1/3 or more of the electrode surface).

6) Interface adhesion test between collector layer and [porous electrode layer + ion exchange layer]

After the water adhering to the surface of the electrode was wiped off with a filter paper, a transparent tape (No. 405, width: 24 mm) manufactured by NICHIBAN Co., Ltd. was attached to the surface of the ion exchange layer, and the air between the ion exchange layer and the tape was extruded by a finger. Next, the end portion of the aforementioned CELLOTAPE (registered trademark) tape was pulled upward in the direction of the vertical electrode surface to carry out a peeling test. The interface adhesion was evaluated by the following determination method.

A: No peeling occurred.

B: A part of the porous electrode layer or the ion exchange layer was peeled off and attached to the CELLOTAPE tape.

C: The porous electrode layer or the ion exchange layer was peeled off and attached to the CELLOTAPE tape.

6) Calculation method of current efficiency

The electrode of the present invention was assembled to the desalination apparatus of the above-mentioned Fig. 3, and the desalination test of the aqueous solution was carried out. The ion concentration of the recovered aqueous solution was measured, and the amount of ions adsorbed to the electrode was calculated. The current efficiency is calculated by the following equation.

Efficiency (%) = mass of adsorbed salt (mol) × 100 / (average value of current in adsorption step (A) × adsorption time (second) / Faraday constant (C / mol))

(1) an electrode composed of a copolymer composed of a vinyl alcohol monomer (A-1) and an ion-exchangeable monomer (A-2) (Synthesis of PVA-1)

The vinyl alcohol-based polymer PVA-1 having a mercapto group at the terminal is synthesized by the method described in JP-A-59-187003 (vinyl alcohol-based polymer having a mercapto group at the end and a method for producing the same). The obtained PVA-1 had a degree of polymerization of 500 and a degree of saponification of 99.5 mol%.

(Synthesis of cationic polymer P-1)

The synthesis of the cationic polymer P-1 is carried out by the method described in JP-A-59-189113. In a 1 L four-necked separable flask equipped with a reflux condenser and a stirring blade, 110 g of water and 167 g of PVA-1 (polyvinyl alcohol having a mercapto group at the end) were poured, and heated to 95 ° C under stirring to dissolve the vinyl alcohol system. After the polymer, it was cooled to room temperature. A 1/2 equivalent concentration of sulfuric acid was added to the aqueous solution to adjust the pH to 3.0. Further, 16 g of methacrylamide-propylammonium trimethylammonium chloride (MAPTAC) was dissolved, and after adding to the previously prepared aqueous solution with stirring, the solution was heated to 70 ° C while being filled with nitrogen gas, and then 70 The nitrogen gas was continuously charged at ° C for 30 minutes, thereby performing nitrogen substitution. After nitrogen substitution, 88.8 mL of a 2.5% aqueous solution of potassium persulfate (KPS) was added to the above aqueous solution in an amount of 1.5 hours to start the block copolymerization. After the copolymerization reaction, the temperature in the system was maintained at 75 ° C. The polymerization was further carried out in an hour, followed by cooling to obtain a cationic polymer of a block copolymer of a vinyl alcohol-based polymer, methyl acrylamidopropyltrimethylammonium chloride (MAPTAC) having a solid concentration of 20%. An aqueous solution of P-1. After drying a part of the obtained aqueous solution, it is dissolved in heavy water, and subjected to ¹ H-NMR measurement, and the measurement result is the content of the cationic monomer in the block copolymer, that is, methacrylamide The ratio of the number of units of the trimethylammonium chloride unit monomer to the total number of monomer units in the polymer was 3 mol%.

(Synthesis of cationic polymer P-2)

The cationic polymer P-2 which is a block copolymer was synthesized by the same method as the cationic polymer P-1 except that the polymerization conditions of the above P-1 were changed in the following Table 1. The ratio of the ion exchange unit of the obtained cationic polymer P-2 was 10 mol%.

(Synthesis of PVA-2)

The vinyl alcohol-based polymer PVA-2 having a mercapto group at the terminal is synthesized by the method described in JP-A-59-187003 (vinyl alcohol-based polymer having a mercapto group at the end and a method for producing the same). The obtained PVA-2 had a degree of polymerization of 1,500 and a degree of saponification of 99.5 mol%.

(Synthesis of cationic polymers P-3, P-4, P-5)

The cationic polymers P-3 and P-4 belonging to the block copolymer were synthesized by the same method as the cationic polymer P-1 by changing the polymerization conditions of the above P-1 in the following Table 1. P-5. The ratio of the ion exchange unit of the obtained cationic polymer P-3 was 40 mol%, the ratio of the ion exchange unit of P-4 was 0.5 mol%, and the ratio of the ion exchange unit of P-5 It is 55 mol%.

(Synthesis of cationic polymer P-6)

In a 6 L separable flask equipped with a stirrer, a temperature sensor, a dropping funnel and a reflux condenser, 1120 g of vinyl acetate, 1680 g of methanol, and methacrylamide containing methacrylamide were poured. 31.6 g of an ammonium 20% by mass methanol solution was subjected to nitrogen substitution in a system under stirring, and then the temperature in the system was raised to 60 °C. To the system, 20 g of methanol containing 0.4 g of 2,2'-azobisisobutyronitrile (AIBN) was added to start a polymerization reaction. From the point of initiation of the polymerization, 200 g of a methanol solution containing 20% by mass of methacrylium amidiumpropyltrimethylammonium chloride was added to the system, and the reaction was carried out for 4 hours to terminate the polymerization reaction. The solid content concentration in the system at the time of stopping the polymerization reaction, that is, the content ratio of the solid content to the entire polymerization slurry was 23.9% by mass. Next, methanol vapor was introduced into the system, whereby unreacted vinyl acetate monomer was driven out to obtain a methanol solution containing 55% by mass of the vinyl ester copolymer.

In the methanol solution containing 55 mass% of the vinyl ester copolymer, the molar ratio of sodium hydroxide to the vinyl acetate unit in the copolymer was 0.025, and the solid content concentration of the vinyl ester copolymer was 45 mass%. In the manner, methanol and a methanol solution containing 10% by mass of sodium hydroxide were added under stirring, and the saponification reaction was started at 40 °C.

As the saponification reaction proceeds, when the colloid is generated, it is taken out from the reaction system to be pulverized, and then, after a lapse of 1 hour after the generation of the gelate, methyl acetate is added to the pulverized material to thereby neutralize, A cationic polymer P-5 which is a vinyl alcohol polymer in a swollen state is obtained. To the swollen cationic polymer, 6 times the mass-based amount (bath ratio 6 times) of methanol was added, and the mixture was washed under reflux for 1 hour, and the solid matter obtained by the subsequent filtration was recovered as the cationic polymerization. Things. The obtained polymer is dried, then dissolved in heavy water, and subjected to ¹ H-NMR measurement, and the measurement result is the content of the cationic monomer in the copolymer, that is, methacrylamide propylamine III The ratio of the number of units of methylammonium chloride monomer to the total number of monomer units in the polymer was 2 mol%. Further, the degree of polymerization was 500, and the degree of saponification was 98.5 mol%.

(Synthesis of cationic polymer P-6)

The cationic polymer P-6 which is a random copolymer was synthesized by the same method as the cationic polymer P-5 except that the composition was changed in the following Table 2. The ratio of the ion exchange unit of the obtained cationic polymer P-6 was 3 mol%. Further, the degree of polymerization was 500, and the degree of saponification was 98.5 mol%.

(Synthesis of anionic polymers P-7, 8, 9, 10, 11)

The anionic polymers P-7, 8, 9, 10, and 11 which are block copolymers were synthesized by the same method as the cationic polymer P-1 except that the composition was changed in the following Table 3. The ratio of the ion exchange units of the obtained anionic polymers P-7, 8, 9, 10, 11 was 3 mol%, 40 mol%, 10 mol%, 0.5 mol%, 55 mol%.

(Synthesis of anionic polymer P-12)

The composition was changed in the same manner as in the above-mentioned cationic polymer P-6, and the composition was changed in the following Table 4 to synthesize a cationic polymer P-12 which is a random copolymer. The ratio of the ion exchange unit of the obtained cationic polymer P-12 was 3 mol%. Further, the degree of polymerization was 500, and the degree of saponification was 98.5 mol%.

Example 1 Production of anion exchange electrode-1 (Modulation of aqueous solution of cationic polymer)

Into a 200 mL Erlenmeyer flask, 90 mL of deionized water was poured and 22.5 g of the cationic polymer P-1 was added, followed by heating and stirring in a water bath at 95 ° C to uniformly dissolve the polymer P-1. Deionized water was added to prepare a cationic polymer aqueous solution having a concentration of 17%. The viscosity is 87,000 mPa. s (20 ° C).

(modulation of slurry containing carbon material)

The activated carbon (BET adsorption area: 1800 m ² /g), conductive carbon black, carboxymethyl cellulose, and water were mixed at a mass ratio of 100:5:1:140, and then kneaded. 20 parts by mass of water and 15 parts by mass of an aqueous SBR emulsion binder (solid content ratio: 40% by mass) were added to 100 parts by mass of the obtained block-like kneaded product, and kneaded to obtain a solid content ratio of 36%. Carbon slurry. The viscosity of the obtained slurry at a temperature of 25 ° C was measured by a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd.), and the measurement result was 3000 mPa. s.

(Production of anion exchange electrode)

A slurry containing a carbon material was applied on a graphite sheet (thickness: 250 μm) using an applicator/bar (coating width: 10 cm). Then, it was dried at a temperature of 90 ° C for 10 minutes using a hot air dryer "DKM400" (manufactured by Yamato Scientific Co., Ltd.). Next, an aqueous solution (concentration: 12% by weight) of the obtained cationic polymer P-1 was applied onto the slurry layer of the drying step to apply an aqueous solution having a thickness of 120 μm. Then, the same drying as described above was carried out to obtain a bubble-free, good-quality integrated electrode. Regarding the thickness of each layer produced, the thickness of the anion exchange layer was 10 μm, and the thickness of the porous electrode layer was 280 μm.

The integrated electrode thus prepared was subjected to 160 ° C for 30 minutes. The heat treatment is carried out to crystallize the vinyl alcohol polymer. Next, the laminate was immersed in a 2 mol/L aqueous sodium sulfate solution for 24 hours. After adding concentrated sulfuric acid to the aqueous solution to adjust the pH to 2.0, the anion exchange integrated electrode was immersed in a 0.5 vol% aqueous solution of glutaraldehyde, and stirred at 50 ° C for 1 hour in a stirrer to carry out a crosslinking treatment. Here, as the glutaraldehyde aqueous solution, a solution obtained by diluting "glutaraldehyde" (25 vol%) manufactured by Shijin Pharmaceutical Co., Ltd. was used. After the crosslinking treatment, the anion exchange integrated electrode described above was immersed in deionized water, and deionized water was replaced several times to prepare an electrode-1. The surface of the produced electrode-1 has a good appearance.

The integrated electrode was dried by a hot air dryer "DKM400" (manufactured by Yamato Scientific Co., Ltd.) at a temperature of 90 ° C for 1 hour, and further dried using a vacuum dryer "DP32" (manufactured by Yamato Scientific Co., Ltd.). The film was dried under vacuum at 50 ° C for 60 hours, and then obtained according to the method described in the above 3) Evaluation of the degree of crosslinking of the ion exchanger on the surface of the electrode, according to the total reflection method by infrared spectroscopy (FT-IR) (ATR method) ( Fig. 7) The degree of crosslinking of the ion exchanger was calculated. As a result, the area ratio of I ₂ /I ₁ was 3.21.

(Evaluation of anion exchange electrode)

The anion exchange electrode-1 prepared as described above was cut into a desired size to prepare a measurement sample. Using the prepared sample, electrode surface (appearance) observation, electrode resistance evaluation, and interface adhesion test were carried out in accordance with the above method. The results obtained are shown in Table 5 below. Further, an electron microscope image of a cross section of the porous electrode layer of the electrode and the cationic polymer layer (vinyl alcohol polymer layer having an anion exchange group) was shown in Fig. 6. In Figure 6, the cationic polymer layer 26 It is formed on the porous electrode layer 25.

Example 2 Production of anion exchange electrode-2

The graphite sheet used in Example 1 was used as a current collector layer (thickness: 250 μm), and a micro film applicator (coating width: 9 cm) manufactured by COATING TESTER Co., Ltd. was used on the current collector layer. The slurry and the aqueous solution are simultaneously applied so that the slurry containing the carbon material is provided on the lower layer side and the aqueous solution (concentration: 12% by weight) of the P-2 is provided on the upper layer side. Then, drying was carried out under the same conditions as described above to obtain an anion exchange integrated electrode. Regarding the thickness of each layer obtained, the thickness of the anion exchange layer was 8 μm, and the thickness of the porous electrode layer was 280 μm.

The anion exchange electrode obtained was subjected to heat treatment in the same manner as in Example 1 and subjected to crosslinking treatment and water washing under the conditions shown in Table 5 to obtain a good anion exchange electrode-2. The results obtained are also listed in Table 5.

Examples 3 to 6

The anion exchange electrode-3 to the anion exchange electrode-6 were produced and evaluated in the same manner as in the above-described anion exchange electrode-2 under the conditions described in Table 5. The evaluation results of the respective electrodes are shown in Table 5.

Comparative example 1

In the same manner as the above-described anion exchange electrode-1, as shown in Table 5, an anion was produced under the same conditions as in Example 1 except that the type of polymer used was changed from P-1 to PVA-1. Electrode-7 was exchanged and evaluated. The evaluation results of the respective electrodes are shown in Table 5.

Comparative example 2, 3

The composition and production conditions were changed in the same manner as in the above-described anion exchange electrode-1, and the anion exchange electrode-8 and the anion exchange electrode-9 were produced and evaluated. The evaluation results of the respective electrodes are shown in Table 5.

Examples 7 to 12

The composition and production conditions were changed in the same manner as in the above-described anion exchange electrode-1, and the cation exchange electrode-10 to the cation exchange electrode-15 was produced and evaluated. The evaluation results of the respective electrodes are shown in Table 6 below.

Comparative Example 4, 5

The composition and production conditions were changed in the same manner as in the above-described anion exchange electrode-1, and the cation exchange electrodes-16 and 17 were produced and evaluated. The evaluation results of the respective electrodes are shown in Table 6.

Comparative Example 6

Referring to Non-Patent Document 1, polyvinyl alcohol is treated with sulfosuccinic acid to prepare an electrode which is crosslinked with a cation exchange side to which a sulfonic acid group is introduced. Pour the solution into 90 mL of deionized water in a 200 mL Erlenmeyer flask and completely dissolve PVA-2 (10.0 g) at 90 ° C for 6 hours. Then, sulfosuccinic acid (5.0 g) manufactured by ALDRICH Co., Ltd. was uniformly dissolved while stirring and dissolving the aqueous solution of PVA-2 for 24 hours. The slurry containing the carbon material was applied onto the graphite sheet by a coating rod and dried by the above method to obtain an electrode in which a layer containing a carbon material was laminated on the graphite sheet. The aqueous solution containing PVA-2 and sulfosuccinic acid was applied to the above electrode by a coating rod to a thickness of 120 μm (thickness of the aqueous solution). Drying was carried out at 60 ° C for 1 hour, and in order to carry out the crosslinking reaction of sulfosuccinic acid, heat treatment at 110 ° C for 1 hour was carried out to obtain a cation exchange electrode 18 in which sulfosuccinic acid was used to reform the polyvinyl alcohol.

In order to evaluate the alkali resistance of the electrode, the electrodes of the electrode 11 and the electrode 18 were each immersed in the above-mentioned NaOH (pH = 14) aqueous solution for one week, and the surface of the electrode after the removal was visually observed and evaluated. The evaluation criteria were: A was not judged when a change was observed on the surface of the electrode, and it was judged to be B when a part of the surface of the electrode was dissolved, and it was judged to be C when it was found that about half of the surface of the electrode was dissolved, and it was judged to be D when almost the entire surface of the electrode was dissolved. . The determination result of the electrode 11 is A, and the electrode 18 is C. This result represents that the ester bond of polyvinyl alcohol and sulfosuccinic acid is decomposed under alkaline conditions, and the alkali resistance is insufficient.

Example 13 (desalting by means of a device incorporating a liquid-through type capacitor)

The above-described anion exchange electrode-1 was used as the electrode 2 having the anion exchange layer 4, and the above-described cation exchange electrode-10 was used as the electrode 3 having the cation exchange layer 7, and the capacitor unit shown in Fig. 1 was assembled. Here, the flow path portion 10 is provided by interposing a separator ("LS60" manufactured by Nippon Special Fabric Co., Ltd., thickness: 90 μm) between the anion exchange electrode-1 and the cation exchange electrode-10. Ten sets of such capacitor units were stacked to produce a liquid-through type capacitor. Here, the capacitor unit is stacked such that the collector layers of the electrodes having the same polarity sign as the fixed charge of the ion exchange layer face each other. The effective size of the electrode is 6 cm x 6 cm. A desalination apparatus having the same configuration as that of the desalination apparatus 15 shown in Fig. 3 except that the assembled through-liquid capacitor was used was produced. A positive electrode of a constant voltage (1.5 V) DC electrode was connected to the anion exchange electrode-1, and a negative electrode was connected to the cation exchange electrode-10, and a voltage was applied between the electrodes. An aqueous solution in which NaCl was dissolved in deionized water and an ion concentration of 500 ppm was supplied to the desalination apparatus. After the ions were adsorbed for 180 seconds with the aqueous solution described above, the liquid was recovered.

(Evaluation of current efficiency)

The ion concentration of the recovered liquid was measured, and the amount of ions adsorbed by the electrode was calculated. Further, the current efficiency is calculated from the above-described calculation formula of the current efficiency. Incidentally, the current efficiency at this time is 91%.

(evaluation of repeat characteristics)

The cleaning system for the electrode after ion adsorption is carried out as follows. An aqueous solution of NaCl (500 ppm) was supplied to the desalination apparatus. A negative electrode of a constant voltage (1.5 V) DC electrode was connected to the anion exchange electrode-1, and a positive electrode was connected to the cation exchange electrode-10, and a voltage was applied between the electrodes. After ion desorption for 60 seconds The aqueous solution containing the desorbed ionic substance is discharged. After the electrode is washed as described above, the desalination device is again used for the adsorption of ions. The adsorption and desorption of ions were repeated for 10 cycles, and there was no significant change in current efficiency.

Examples 14 to 17, Comparative Examples 7 to 9

The desalination apparatus was fabricated and the current efficiency was measured except that the electrode having the anion exchange layer and the electrode having the cation exchange layer were changed to the combinations listed in Table 7 below. The obtained measurement results are shown in Table 7.

Comparative Example 10

A slurry containing a carbon material (BET adsorption area of activated carbon: 2200 m ² /g, concentration: 38 wt%, viscosity: 3000 mPa·s) was applied onto the graphite sheet by a coating bar (coating width: 10 cm). Then, drying was performed under the same conditions as described above to obtain an electrode in which a porous electrode layer containing a carbon material was formed on the current collector layer. The thickness was calculated by a DIGIMATIC micrometer manufactured by Mitutoyo Co., Ltd., and the thickness of the porous electrode layer was 280 μm. Next, a commercially available anion exchange membrane AMX (manufactured by ASTOM Co., Ltd.) having a quaternary ammonium group and a commercially available cation exchange membrane CMX (manufactured by ASTOM Co., Ltd.) having a sulfonic acid group were pressure-bonded to the surface of the porous electrode layer. An ion exchange membrane crimping type electrode was produced. The electrode was used in the same manner as in Example 13 to prepare a desalination apparatus and its current efficiency was evaluated. The current efficiency at this time was 80%.

From the results of Tables 5 and 6, it can be seen that in the integrated electrode formed by laminating a porous electrode layer containing a carbon material and an anion exchange layer or a cation exchange layer, the degree of crosslinking of the present invention is controlled to 4.30 or less. Thus, the electrodeless interface is peeled off, and a homogeneous and good electrode can be obtained. Further, it is also known that the electrode resistance is also low, exhibiting excellent performance as an electrode (Examples 1 to 6, Examples 7 to 12). It is also known that the electrode resistance is particularly low especially when the ratio of the ion exchange unit is 3 mol% or more (Examples 1 to 3, Examples 5, 6, Examples 9 to 11, and Examples 13, 14). On the other hand, when polyvinyl alcohol to which an ion exchange unit was not introduced was used for the electrode (Comparative Example 1), the obtained electrode resistance value became large. Further, when the electrode having the degree of crosslinking of the ion exchanger formed on the outermost layer of the ion exchange layer was formed to fall outside the above range (Comparative Examples 2 to 5), the ion exchange layer was dissolved and could not be maintained as an integral type. The form of the electrode (Comparative Examples 2 and 4) or the swelling was remarkable, and the state of the surface of the electrode after water immersion was deteriorated (Comparative Examples 3 and 5).

From the results of Table 7, it can be seen that when used in a liquid-through capacitor When the electrode was a vinyl alcohol polymer to which an ion exchange unit was introduced, the electrode exhibited excellent current efficiency (Examples 13 to 17). In particular, when the ratio of the ion exchange unit is 3 mol% or more (Examples 13 to 15 and Example 16), the current efficiency is particularly excellent. It is also known that when the electrode of polyvinyl alcohol which is not introduced into the ion exchange unit is used, the current efficiency is deteriorated (Comparative Example 7). Further, when the liquid-exchange type capacitor is used in an electrode in which the degree of crosslinking of the ion exchanger formed in the outermost layer of the ion-exchange layer falls outside the above range, the swelling of the ion-exchange layer becomes conspicuous, and stable high is not exhibited. Current density (Comparative Examples 8, 9). Further, regarding the type in which a commercially available hydrocarbon-based film was pressure-bonded to the porous electrode layer, it was confirmed that the current efficiency was low (Comparative Example 10).

(2) an electrode composed of a mixture (B1+B2) of a vinyl alcohol polymer (B-1) and a polymer (B-2) having an ion exchange group (Manufacture of ion exchanger P-101 containing cationic polymer)

In a 1 L four-necked separable flask equipped with a reflux condenser and a stirring blade, 16 g of methacrylamidopropyltrimethylammonium chloride (MAPTAC) was dissolved in 669 g of water and stirred at 95 ° C under stirring. After completely dissolving, after cooling to room temperature, a 1/2 equivalent concentration of sulfuric acid was added to the aqueous solution to adjust the pH to 3.0. While the aqueous solution was purged with nitrogen gas, the mixture was heated to 70 ° C, and nitrogen gas was continuously charged at 70 ° C for 30 minutes to carry out nitrogen substitution. After nitrogen substitution, 88.8 mL of a 2.5% aqueous potassium persulfate (KPS) solution was added to the aqueous solution in an amount of 1.5 hours to start the polymerization reaction. After the reaction was allowed to proceed, the temperature in the system was maintained at 75 ° C for 1 hour to further the polymerization. This was carried out, followed by cooling to obtain a polymer of methacrylamidopropyltrimethylammonium chloride (MAPTAC). Then, 110 g of polyvinyl alcohol (PVA-3: degree of polymerization 1700, degree of saponification 98.5 mol%) was dissolved in the aqueous solution to obtain an aqueous solution of the ion exchanger P-101 containing a cationic polymer. A part of the obtained aqueous solution was dried, dissolved in heavy water, and subjected to ¹ H-NMR measurement, and the measurement result was the content of the cationic monomer in the aqueous solution, that is, methacrylamide-propyltrimethyl The ratio of the number of units of the ammonium chloride unit monomer to the total number of monomer units in the aqueous solution was 3 mol%.

(Manufacture of ion exchangers P-102, 103, 104, 105 containing a cationic polymer)

The ion exchanger P-102 containing a cationic polymer was produced by the same method as the ion exchanger P-101 containing a cationic polymer, except that the polymerization conditions of P-101 described above were changed as shown in the following Table 8. P-103, P-104, P-105. The ratio of the ion exchange unit of the obtained cationic polymer-containing ion exchanger P-102 was 10 mol%, 40 mol% of P-103, 0.5 mol% of P-104, and 55 mol% of P-105.

(Manufacture of ion exchangers P-106, 107, 108, 109, 110 containing anionic polymer)

The ion exchange body P, which is a mixture of an anionic polymer and a vinyl alcohol polymer, was produced by the same method as the method for producing the ion exchanger P-101 containing a cationic polymer, except that the composition was changed in the following Table 9. -106, 107, 108, 109, 110. The ratio of the ion exchange units of the obtained anion-containing ion exchangers P-106, 107, 108, 109, and 110 was 3 mol%, 10 mol%, 40 mol%, 0.5 mol%, and 55 mol%, respectively.

Example 18 Production of anion exchange electrode-101 (Preparation of an aqueous solution of an ion exchanger containing a cationic polymer)

Pour 90 mL of deionized water into a 200 mL Erlenmeyer flask and add 22.5 g of a cationic polymer-containing ion exchanger P-101, and then heat and stir in a 95 ° C water bath to uniformly dissolve the ion exchanger P-101. . Deionized water was added to prepare an aqueous solution of a cationic polymer-containing ion exchanger having a concentration of 17%. The viscosity is 87,000 mPa. s (20 ° C).

(modulation of slurry containing carbon material)

The activated carbon (BET adsorption area: 1800 m ² /g), conductive carbon black, carboxymethyl cellulose, and water were mixed at a mass ratio of 100:5:1:140, and then kneaded. 20 parts by mass of water and 15 parts by mass of an aqueous SBR emulsion binder (solid content ratio: 40% by mass) were added to 100 parts by mass of the obtained block kneaded product, and kneaded to obtain a solid content ratio of 36% by mass. Activated carbon slurry. The viscosity of the obtained slurry at a temperature of 25 ° C was measured by a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd.), and the measurement result was 3000 mPa. s.

(Production of anion exchange electrode)

A slurry containing a carbon material was applied onto the above graphite sheet (thickness: 250 μm) using a coating bar (coating width: 10 cm). Then, it was dried at a temperature of 90 ° C for 10 minutes using a hot air dryer "DKM400" (manufactured by Yamato Scientific Co., Ltd.). Next, an aqueous solution (concentration: 12% by weight) of the ion exchanger P-101 containing the above-mentioned obtained cationic polymer was applied onto the slurry layer of the drying step to apply an aqueous solution having a thickness of 120 μm. Then, the same drying as described above was carried out to obtain a bubble-free, good-quality integrated electrode. The thickness of the anion exchange layer after the drying of each layer produced was 10 μm, and the thickness of the porous electrode layer was 280 μm.

The integrated electrode thus obtained was heat-treated at 160 ° C for 30 minutes to partially crystallization of polyvinyl alcohol. Next, a layered product composed of a graphite sheet, a porous electrode layer, and an ion exchange layer was immersed in a 2 mol/L sodium sulfate aqueous solution for 24 hours. After adding concentrated sulfuric acid to the aqueous solution to adjust the pH to 2.0, the anion exchange integrated electrode was immersed in a 0.5 vol% aqueous solution of glutaraldehyde, and stirred at 50 ° C for 1 hour in a stirrer to carry out a crosslinking treatment. Here, in terms of an aqueous solution of glutaraldehyde, A solution obtained by diluting "glutaraldehyde" (25 vol%) manufactured by Shijin Pharmaceutical Co., Ltd. was used. After the crosslinking treatment, the anion exchange integrated electrode described above was immersed in deionized water, and deionized water was replaced several times to prepare an electrode-101. The surface of the electrode-101 produced has a good appearance.

The integrated electrode was dried by a hot air dryer "DKM400" (manufactured by Yamato Scientific Co., Ltd.) at a temperature of 90 ° C for 1 hour, and further dried using a vacuum dryer "DP32" (manufactured by Yamato Scientific Co., Ltd.). The temperature was dried at 50 ° C for 60 hours, and then according to the method described in the above 3) evaluation of the degree of crosslinking of the ion exchanger (A) on the surface of the electrode, according to the total reflection method by infrared spectroscopy (FT-IR) (ATR method) The obtained spectrum (Fig. 9) was calculated for the degree of crosslinking of the ion exchanger (A), and as a result, the area ratio of I ₂ /I ₁ was 3.31.

(Evaluation of anion exchange electrode)

The anion exchange electrode-101 prepared as described above was cut into a desired size to prepare a measurement sample. Using the prepared sample, electrode surface (appearance) observation, electrode resistance evaluation, and interface adhesion test were carried out in accordance with the above method. The results obtained are shown in Table 10 below. Further, an electron microscope image of a cross section of a porous electrode layer of the electrode and a polymer layer containing a cationic polymer (a polymer mixed layer composed of a polymer having an anion exchange group and a vinyl alcohol polymer) Shown in Figure 8.

Example 19 Production of anion exchange electrode-102

The graphite sheet used in Example 18 was used as a current collector layer (thickness: 250 μm), and on the current collector layer, COATING TESTER was used. The two-layer type film applicator (coating width: 9 cm) manufactured by the company of Co., Ltd. is coated with the slurry containing the carbon material on the lower layer side and the aqueous solution (concentration: 12% by weight) of the P-102 on the upper layer side. The slurry and the aqueous solution. Then, drying was carried out under the same conditions as described above to obtain an anion exchange integrated electrode. Regarding the thickness of each layer obtained, the thickness of the anion exchange layer was 10 μm, and the thickness of the porous electrode layer was 280 μm.

The anion exchange electrode obtained was subjected to heat treatment in the same manner as in Example 18, and subjected to crosslinking treatment and water washing under the conditions shown in Table 12 below to obtain a good anion exchange electrode-102. The results obtained are also shown in Table 10.

Examples 20 to 22

In the same manner as in the above-described anion exchange electrode-102, an anion exchange electrode-103 to an anion exchange electrode-105 was produced and evaluated under the conditions described in Table 10. The evaluation results of the respective electrodes are shown in Table 10.

Comparative Example 11

In the same manner as the above-described anion exchange electrode-101, as shown in Table 10, an anion was produced under the same conditions except that the polymer type used was changed from P-101 to PVA-3 in Example 18. Electrode-106 was exchanged and evaluated. The evaluation results of the respective electrodes are shown in Table 10.

Comparative Examples 12, 13

The composition and production conditions were changed in the same manner as in the above-described anion exchange electrode-101, and the anion exchange electrode-107 and the anion exchange electrode-108 were produced and evaluated. The evaluation results of the respective electrodes are shown in Table 10.

Examples 23 to 27

The composition and production conditions were changed in the same manner as in the above-described anion exchange electrode-101, and the cation exchange electrode-109 to the cation exchange electrode-113 were produced and evaluated. The evaluation results of the respective electrodes are shown in Table 11 below.

Comparative Examples 14, 15

The composition and production conditions were changed in the same manner as in the above-described anion exchange electrode-101, and the cation exchange electrodes -114 and 115 were produced and evaluated. The evaluation results of the respective electrodes are shown in Table 11.

Example 28 (desalting by means of a device incorporating a liquid-through type capacitor)

The above-described anion exchange electrode-101 was used as the electrode 2 having the anion exchange layer 4, and the above-described cation exchange electrode-109 was used as the electrode 3 having the cation exchange layer 7, and the capacitor unit shown in Fig. 1 was assembled. Here, the flow path portion 10 is provided by interposing a separator ("LS60" manufactured by Nippon Special Fabric Co., Ltd., thickness: 90 μm) between the anion exchange electrode-101 and the cation exchange electrode-109. Ten sets of such capacitor units were stacked to produce a liquid-through type capacitor. Here, the capacitor unit is stacked such that the collector layers of the electrodes having the same polarity sign as the fixed charge of the ion exchange layer face each other. The effective size of the electrode is 6 cm x 6 cm. A desalination apparatus having the same configuration as that of the desalination apparatus 15 shown in Fig. 3 except that the assembled through-liquid capacitor was used was produced. A positive electrode of a constant voltage (1.5 V) DC electrode was connected to the anion exchange electrode -101, and a negative electrode was connected to the cation exchange electrode -109, and a voltage was applied between the electrodes. An aqueous solution in which NaCl was dissolved in deionized water and an ion concentration of 500 ppm was supplied to the desalination apparatus. After the ions were adsorbed for 180 seconds with the aqueous solution described above, the liquid was recovered.

(Evaluation of current efficiency)

The ion concentration of the recovered liquid was measured, and the amount of ions adsorbed by the electrode was calculated. Further, the current efficiency is calculated from the above-described calculation formula of the current efficiency. Incidentally, the current efficiency at this time is 90%.

(evaluation of repeat characteristics)

The cleaning system for the electrode after ion adsorption is carried out as follows. An aqueous solution of NaCl (500 ppm) was supplied to the desalination apparatus. Constant voltage (1.5V) DC The anode of the pole is connected to the anion exchange electrode-101, and the anode is connected to the cation exchange electrode-109, and a voltage is applied between the electrodes. After the ion desorption was performed for 60 seconds, the aqueous solution containing the desorbed ionic substance was discharged. After the electrode is washed as described above, the desalination device is again used for the adsorption of ions. The adsorption and desorption of ions were repeated for 10 cycles, and there was no significant change in current efficiency.

Examples 29 to 32 and Comparative Examples 16 to 18

The desalination apparatus was produced and the current efficiency was measured except that the electrode having the anion exchange layer and the electrode having the cation exchange layer were changed to the combination shown in Table 12 below. The obtained measurement results are shown in Table 12.

Comparative Example 19

A slurry containing a carbon material (BET adsorption area of activated carbon: 2200 m ² /g, concentration: 38 wt%, viscosity: 3000 mPa·s) was applied onto the graphite sheet by a coating bar (coating width: 10 cm). Then, drying was performed under the same conditions as described above to obtain an electrode in which a porous electrode layer containing a carbon material was formed on the current collector layer. The thickness was calculated by a DIGIMATIC micrometer manufactured by Mitutoyo Co., Ltd., and the thickness of the porous electrode layer was 280 μm. Next, a commercially available anion exchange membrane AMX (manufactured by ASTOM Co., Ltd.) having a quaternary ammonium group and a commercially available cation exchange membrane CMX (manufactured by ASTOM Co., Ltd.) having a sulfonic acid group were pressure-bonded to the surface of the porous electrode layer. An ion exchange membrane crimping type electrode was produced. This electrode was used in the same manner as in Example 30 to prepare a desalting apparatus and evaluate its current efficiency. The current efficiency at this time was 80%.

From the results of Tables 10 and 11, it is understood that the integrated electrode formed by laminating a porous electrode layer containing a carbon material and an anion exchange layer or a cation exchange layer has a degree of crosslinking controlled to 4.30 or less. The electrode of the ion exchange layer of the ion exchanger has an electrodeless interface and is a homogeneous and good electrode. Further, it is also known that the electrode resistance is also low, exhibiting excellent performance as an electrode (Examples 18 to 22, Examples 23 to 27). In particular, when the ratio of the ion exchange unit is from 3 mol% to 40 mol% (Examples 18 to 20 and Examples 23 to 25), the electrode resistance is particularly low, and an electrode having excellent durability can be obtained. On the other hand, when polyvinyl alcohol to which an ion exchange unit was not introduced was used for the electrode (Comparative Example 11), the obtained electrode resistance value became large. Further, when the electrode having the degree of crosslinking of the ion exchanger (A) formed on the outermost layer thereof falls outside the above range (Comparative Examples 12 to 15), the ion exchange layer is dissolved and cannot be maintained as an integral electrode. The morphology (Comparative Examples 12 and 14) or the swelling of the surface of the electrode after water immersion was deteriorated (Comparative Examples 13 and 15).

From the results of Table 12, it can be seen that when used in a liquid-through type capacitor The electrode used was excellent in current efficiency when the ion exchange layer contained a mixture of a polymer having an ion exchange group and a vinyl alcohol polymer (Examples 28 to 32). In particular, when the ratio of the ion exchange unit is from 3 mol% to 40 mol% (Examples 28 to 30), the current efficiency is particularly excellent. On the other hand, when an electrode of polyvinyl alcohol which is not introduced into the ion exchange unit is used for the liquid-through type capacitor (Comparative Example 16), and when the through-liquid type capacitor is used, the ion exchanger formed at the outermost layer (A) is used. When the degree of crosslinking of the electrode falls outside the above range, the swelling of the ion exchange layer becomes remarkable, and a stable high current density is not exhibited (Comparative Examples 17, 18). Further, regarding the type in which a commercially available hydrocarbon-based film was pressure-bonded to the porous electrode layer, it was confirmed that the current efficiency was low (Comparative Example 19).

[Industrial availability]

The liquid-pass type capacitor using the electrode of the present invention is capable of performing desalination and separation of an ionic substance and a non-ionic substance with high efficiency and stability for a long period of time, and thus has industrial applicability.

The preferred embodiments of the present invention have been described above with reference to the drawings, and those skilled in the art will be able to devise various changes and modifications within the scope of the invention. Therefore, such changes and modifications are to be construed as falling within the scope of the invention as defined by the scope of the claims.

Claims (15)

An electrode comprising an electrode of a porous electrode layer and an ion exchange layer on a current collector layer; the porous electrode layer containing a carbon material; the ion exchange layer containing an ion exchanger (A), and the ion exchanger (A) contains (1) a copolymer (A1+A2) composed of a vinyl alcohol monomer (A-1) and an ion-exchangeable monomer (A-2), or (2) a vinyl alcohol polymer. (B-1) and a mixture (B1+B2) of a polymer (B-2) having an ion exchange group, the ion exchange system being crosslinked by forming an acetal crosslinked crosslinking agent, the ion exchanger The degree of crosslinking is in the range of 4.30 or less. The electrode of claim 1, wherein in the aforementioned ion exchanger (A), the molar ratio of the vinyl alcohol unit to the ion exchange unit in the aforementioned copolymer or the aforementioned mixture is in the range of 99.5:0.5 to 50:50. The electrode of claim 1 or 2, wherein the copolymer (A1+A2) is a polymer having a vinyl alcohol polymer (a-1) and an ion exchange group (a) with respect to the ion exchanger (A). -2) Formed block copolymer. The electrode of claim 1 or 2, wherein the copolymer (A1+A2) is a polymer having a vinyl alcohol polymer (a-1) and an ion exchange group (a) with respect to the ion exchanger (A). -2) A graft copolymer formed. The electrode according to any one of claims 1 to 4, wherein the porous electrode layer formed on the current collector layer and the ion exchange layer are laminated in the order of the current collector layer/porous electrode layer/ion exchange layer. The electrode according to any one of claims 1 to 5, wherein the thickness of the aforementioned ion exchange layer formed on the porous electrode layer is in the range of 70 μm. Next, the thickness of the porous electrode layer ranges from 100 μm to 1000 μm. The electrode according to any one of claims 1 to 4, wherein the ion exchange layer is impregnated in the porous electrode layer. An electrode for a liquid-through type capacitor, comprising the electrode according to any one of claims 1 to 7. A method for producing an electrode according to any one of claims 1 to 7, wherein a slurry containing a carbon material and a solution containing the ion exchanger (A) are simultaneously or separately applied to the surface of the current collector layer, and then the coating film is dried. The ion exchanger (A) is crosslinked to form the porous electrode layer and the ion exchange layer. The method for producing an electrode according to claim 9, wherein the slurry containing the carbon material and the solution containing the ion exchanger (A) are simultaneously applied to the surface of the current collector layer. The method for producing an electrode according to claim 9, wherein after the slurry containing the carbon material is applied onto the current collector layer, a solution containing the ion exchanger (A) is applied to the surface of the slurry. The method for producing an electrode according to any one of claims 9 to 11, wherein after the coating film is dried, the crosslinking treatment is performed by heat treatment or without heat treatment. A liquid-pass type capacitor in which the electrodes of claim 8 are arranged to face each other, and a flow path portion is formed between the electrodes, wherein the ion exchanger (A) in one of the electrodes is a cation exchange layer having an anionic group. (1) consisting of a copolymer of the aforementioned vinyl alcohol monomer and a cation exchange monomer or (2) exchanging the aforementioned vinyl alcohol polymer with the aforementioned cation A mixture of polymers, the ion exchanger (A) in the other electrode is an anion exchange layer having a cationic group, and (3) is a copolymer of the aforementioned vinyl alcohol monomer and an anion exchange monomer. The composition or (4) is composed of a mixture of the vinyl alcohol polymer and the anion exchange polymer, and the anion exchange layer and the cation exchange layer are disposed to face each other with the flow path portion interposed therebetween. A desalination device comprising: a liquid-through type capacitor according to claim 13; a container for accommodating the liquid-pass type capacitor; and a DC power source, wherein the positive electrode and the negative electrode of the DC power source are exchangeably connected to the respective electrodes, and the container has A supply port for a liquid containing an ionic substance to be desalted by a liquid-through type capacitor, and a discharge port of the liquid after desalting. A desalination method using a desalination method of a liquid containing an ionic substance according to the desalination apparatus of claim 14; the desalination method comprising the steps of: the first step of using an electrode having an anion exchange layer as a positive electrode; The electrode of the cation exchange layer is a negative electrode, a voltage is applied to each electrode by a DC power source, a liquid containing an ionic substance is supplied to a flow path portion between electrodes to which a voltage is applied, and ions in the liquid are adsorbed by the porous electrode layer, and then The liquid is discharged and recovered; and in the second step, the liquid is supplied to the flow path portion, the electrode having the anion exchange layer is the negative electrode, the electrode having the cation exchange layer is the positive electrode, and the voltage is applied to each electrode by the DC power source. This desorbs the ions adsorbed by the porous electrode layer in the first step, and then discharges the liquid containing the desorbed ions.