JP2013218868A - Ion exchange membrane and method for producing the same, redox flow battery, and fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further improve durability in use of an ion exchange membrane used for a redox flow battery or the like, and also improve handleability in membrane use to achieve a reduction in labor hours and an increase in yield.SOLUTION: A sulfonic acid group-containing polymer having a polar group on an aromatic ring is impregnated in a glass fiber base material to be compounded, so that charge/discharge durability and handleability as a polymer electrolyte membrane used for a redox flow battery or the like is improved.

Description

The present invention relates to an ion exchange membrane with improved durability during use, and as uses, pure water production, salt production, seawater desalination, wastewater treatment and recovery of useful substances, fuel cells, redox flow batteries It is used suitably for etc.
In addition, although the durability improvement in a redox flow battery use is mentioned as an example by the following description, the ion exchange membrane of this invention is not limited to this description, It can be used for the use of all the ion exchange membranes.

In recent years, new secondary batteries excellent in energy efficiency and environmental performance have attracted attention. In particular, in order to store natural energy such as sunlight and wind power, a large secondary battery is strongly demanded. Among these, the redox flow battery is excellent in charge / discharge cycle resistance and safety, and is optimal for a large-sized secondary battery.

  A redox flow battery is generally a battery that obtains energy by causing a redox reaction of vanadium in a vanadium sulfate solution by circulation of a pump. In this redox flow battery, a proton exchange membrane or an anion exchange membrane is used in order to maintain an ion balance between both electrodes.

For the anion exchange membrane, Selemion APS manufactured by Asahi Glass Co., Ltd. is used. However, since an anion exchange membrane needs to pass ions having a large ion radius such as sulfate anion, there is a problem that resistance is high.

In addition to proton conductivity, the proton exchange membrane must have characteristics such as prevention of permeation of the electrolyte and mechanical strength. As such a proton exchange membrane, for example, a membrane containing a perfluorocarbon sulfonic acid polymer introduced with a sulfonic acid group represented by Nafion (registered trademark) manufactured by DuPont of the United States, or a polystyrene sulfone as a hydrocarbon membrane can be used. A film containing an acid cross-linked product is used.

A membrane containing a perfluorocarbon sulfonic acid polymer such as Nafion has advantages of excellent chemical durability, high proton conductivity, and low cell resistance. However, Nafion also has a problem of poor ion permeation selectivity. Specifically, vanadium ions are also allowed to pass during charging / discharging, so that the amount of active material in the electrolytic solution is reduced and the charging / discharging cycle is significantly deteriorated. In addition, there are problems of high cost and large environmental load at the time of disposal.

On the other hand, a hydrocarbon membrane containing a polystyrene sulfonate crosslinked product has advantages such as low cost, difficulty in passing vanadium ions, and excellent ion permeation selectivity. However, there are problems in chemical durability and heat resistance, such as sulfonic acid groups being eliminated during hydrolysis and heat generation.

In view of this, several techniques have been proposed for achieving both high proton conductivity and high durability in proton exchange membranes. For example, in Patent Document 1 and Patent Document 2, a sulfonic acid group is introduced into an aromatic polymer to improve mechanical strength and heat resistance. Many proposals as shown in Patent Documents 3 to 12 have also been made in a method of imparting mechanical strength and durability by a combination of a polymer electrolyte and a porous substrate.
However, most of these techniques are optimized for fuel cell applications, and few techniques optimized for redox flow battery applications have been developed.

In Non-Patent Document 1, sulfonated polyether ether ketone is used for redox flow battery applications, and charge / discharge characteristics superior to Nafion are reported. However, even with these methods, energy efficiency and voltage efficiency are insufficient.

Japanese National Patent Publication No. 11-502245 Japanese Patent Laid-Open No. 2004-10631 JP 2004-356075 A JP 2005-166557 A JP 2004-296409 A JP 2003-41031 A JP 2006-128066 A JP 2005-276747 A JP 2008-1112712 A JP 2010-40530 A JP 2008-71706 A JP 2011-246695 A

Journal of Power Sources (China) 2011, 195, p. 4380-4383

  As another problem, these membranes were used as thin as possible because of their permeation performance and because of material cost problems, but there was a problem that the handling properties of a single membrane deteriorated as the thickness became thinner. .

  However, since the durability of the redox flow membrane is a very important requirement that affects the durability of the entire battery, further improvement is essential, and it is handled from the viewpoint of reducing labor during use and improving yield. Improvement of sex was also essential.

  Therefore, the present inventors have intensively studied to achieve the above object, and by impregnating a glass fiber base material with a sulfonic acid group-containing polymer having a polar group on an aromatic ring, the present invention can be further filled as a redox flow membrane. It has been found that discharge durability and handleability are improved.

That is, this invention consists of the following structures.
[1] A composite membrane containing an aromatic hydrocarbon polymer electrolyte having an anionic group in a glass fiber substrate having a strength of 0.4 MPa or more, the aromatic hydrocarbon polymer The electrolyte contains a solvent, the composite membrane has a thickness of 10 μm or more, and the aromatic hydrocarbon polymer electrolyte contains a constituent represented by the general formula (1) and has at least sulfone as the anionic group. An ion exchange membrane having an acid group.

However, X is a monovalent or divalent group, and any of a nitrile group, an alkoxy group, an amino group, an amide group, an ester group, and a carboxyl group, and Z is any of an oxygen atom, a sulfur atom, a sulfonyl group, and a direct bond Ar ′ represents a divalent aromatic group.
[2] The aromatic hydrocarbon polymer electrolyte further includes a constituent represented by the general formula (2), and the general formula (1) is a constituent represented by the general formula (3). The ion exchange membrane according to [1], which is characterized.

Here, Ar represents a divalent aromatic group, Z represents a sulfonyl group or a carbonyl group, and X represents H or a monovalent or divalent cation species.

However, Ar ′ represents a divalent aromatic group.

[3] In the electrolyte composite membrane, when the total amount of anionic groups in the aromatic hydrocarbon polymer electrolyte is 100 mol%, 80 mol% or more of the anionic groups are alkali metal or alkaline earth. The ion exchange membrane according to any one of [1] and [2], wherein a salt is formed with a metal cation.
[4] The ion exchange membrane according to [3], wherein the cation is one or more selected from the group consisting of sodium ion, potassium ion, cesium ion, magnesium ion, and calcium ion.
[5] In the electrolyte composite membrane, when the total amount of anionic groups of the aromatic hydrocarbon polymer electrolyte is 100 mol%, 90 mol% or more of the anionic groups are free acids. The ion exchange membrane according to any one of [1] and [2].
[6] The content of the sulfonic acid group in the aromatic hydrocarbon polymer electrolyte is in the range of 0.1 to 5.0 meq / g, any one of [1] to [5] An ion exchange membrane as described in 1.

[7] The ion exchange membrane is composed of a composition containing 50 to 100% by mass of the aromatic hydrocarbon polymer electrolyte according to any one of [1] and [2]. The ion exchange membrane according to any one of [6].
[8] The ion exchange membrane according to any one of [1] to [7], wherein the glass fiber substrate is any one of glass yarn, glass cloth, glass paper, and glass grid.
[9] The method for producing an ion exchange membrane according to any one of [1] to [8], wherein a solution in which an aromatic hydrocarbon polymer electrolyte having an anionic group is dissolved in a solvent is used as a glass fiber. A method for producing an ion exchange membrane, comprising impregnating a substrate and then removing the solvent to form a composite membrane having a thickness in the range of 5 to 300 µm.
[10] A redox flow battery using the ion exchange membrane according to any one of [1] to [8].
[11] A fuel cell using the ion exchange membrane according to [1], [2] or [5].

  The composite electrolyte membrane obtained by impregnating the glass fiber base material with a solution obtained by dissolving the aromatic hydrocarbon polymer electrolyte of the present invention in a solvent and then removing the solvent provides durability against membrane breakage during use. In addition, it has become possible to reduce work time and improve yield by improving handling. This effect is not only applied to the illustrated redox flow battery, but is also a general application as an ion exchange membrane, pure water production, salt production, seawater desalination, wastewater treatment and recovery of useful substances, and further a fuel cell It is possible to apply to.

FIG. 1 shows a schematic diagram of a vanadium redox flow battery.

  The ion exchange membrane of the present invention provides a composite electrolyte membrane obtained by impregnating a glass fiber substrate with a solution obtained by dissolving an aromatic hydrocarbon polymer electrolyte having an anionic group in a solvent, and then removing the solvent. As a composite effect, the aromatic hydrocarbon polymer electrolyte alone is reinforced with a glass fiber substrate, and the composite is made rigid so that the membrane can be used in post-processing and when used in a jig for use. To improve the handleability.

  Hereinafter, the ion exchange membrane of the present invention and the production method thereof will be described in detail in the order of an aromatic hydrocarbon polymer electrolyte, an aromatic hydrocarbon polymer electrolyte solution, and a composite membrane. As long as the ion exchange membrane according to the present invention is produced through the above steps, the aromatic hydrocarbon polymer constituting the polymer electrolyte and its solution impregnation, casting, solvent removal method, washing method, etc. Is not particularly limited.

(Aromatic hydrocarbon electrolyte)
The aromatic hydrocarbon electrolyte used in the present invention is composed of an aromatic hydrocarbon polymer having an anionic group, and preferably at least a part of the anionic group forms a salt.
The above aromatic hydrocarbon polymer has an aromatic ring in the polymer main chain, and this aromatic ring is a single bond, ether bond, sulfone bond, imide bond, heterocyclic bond, ester bond, amide bond, urethane bond. , A non-fluorinated or partially fluorinated ion-conducting polymer having a structure bonded with at least one linking group selected from a sulfide bond, a carbonate bond, and a ketone bond.
Examples of the aromatic hydrocarbon polymer having such a structure include polyparaphenylene, polyphenylene oxide, polysulfone, polyethersulfone, polyimide, polyphenylquinoxaline, polybenzoxazole, polybenzthiazole, polybenzimidazole, aromatic polyester, Aromatic polyamide, aromatic polyurethane, polyphenylene sulfide, polyphenylene sulfide sulfone, aromatic polycarbonate, polyaryl ketone, polyether ketone (polyether ketone, polyether ketone ketone, polyether ether ketone, polyether ether ketone ketone, polyether Ketone ether ketone ketone, polyether ketone sulfone) and the like. The aromatic hydrocarbon electrolyte may be composed of these aromatic hydrocarbon polymers alone or in combination of two or more. In particular, aromatic hydrocarbon polymers include polyarylene polymers such as poly (p-phenylene) and poly (m-phenylene); polysulfone, polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene oxide, polyether sulfone, polyether ketone. A polyarylene (thio) ether-based polymer such as a polyarylene; preferably the polyarylene / polyarylene (thio) ether copolymer-based polymer, and may have a side chain composed of an aromatic group or an aliphatic group. Good.
Examples of the anionic group possessed by the aromatic hydrocarbon polymer include a sulfonic acid group, a phosphonic acid group, a carboxyl group, a sulfonamide group, a sulfonimide group, and derivatives thereof. The aromatic hydrocarbon-based polymer may be configured to have only one of these anionic groups or may be configured to have two or more types. In the present invention, it preferably has a sulfonic acid group or a phosphonic acid group. The anionic group may be held at any position of the aromatic hydrocarbon polymer, for example, on the aromatic ring constituting the polymer main chain, on the aromatic group constituting the polymer side chain, or on the aliphatic group. And an embodiment having an anionic group.
The anionic group possessed by the aromatic hydrocarbon polymer of the present invention is preferably at least partially formed as a salt. Examples of such a salt include monovalent or divalent cation salts other than protons. preferable. When the valence is 3 or more, the aromatic hydrocarbon electrolyte solution may gel, or the resulting polymer electrolyte membrane may have a poor shape. Examples of the monovalent cation include alkali metal ions such as lithium, sodium, potassium, and cesium, and monoammonium salts. Alkali metal ions are preferable, and sodium, potassium, and cesium are more preferable. As the divalent cation, alkaline earth metal ions such as beryllium, magnesium, calcium, and barium are preferable, and magnesium and calcium salts are more preferable. The salt of the anionic group may be composed of a single type of salt selected from the group of these monovalent cation salts, or may be composed of a plurality of types of salts obtained by combining two or more types.
In the present invention, the amount of the anionic group forming the salt needs to be in the range of 0.1 to 5.0 meq / g, and preferably 0.2 to 4.0 meq / g. More preferably, it is 0.3 to 3.5 meq / g. When the amount of the anionic group is less than 0.1 meq / g, the effect as a battery is not exhibited, and when it exceeds 5.0 meq / g, the polymer is dissolved in the solution of the redox flow battery.
In the present invention, the salt conversion rate (cation substitution rate) of the anionic group is preferably 80 mol% or more, more preferably 90 mol% or more, and further preferably 99 mol% or more. The reason is as follows. That is, when the acidic group does not form a salt, the aromatic hydrocarbon polymer may be decomposed by heat or the like in the process of forming the composite membrane. Therefore, in the process of forming the polymer electrolyte membrane, the acidic group is made into a salt form, and is converted into protons by an acidic solution treatment as necessary after the film formation. What is necessary is just to choose freely the salt change rate of the anionic group as a final form with respect to a use. For example, when it is advantageous from the viewpoint of battery performance that the anionic group is a free acid, such as a fuel cell, the form of the free acid may be selected. On the other hand, when the anionic group is advantageous in the form of a salt, Choose a form.
The aromatic hydrocarbon electrolyte used in the present invention includes a segmented block copolymer, a polymer having a long chain or a short chain branch (for example, a homopolymer or a random copolymer of the above aromatic hydrocarbon polymer) , Comb polymers, and the like) and star polymers. In particular, the use of a copolymer that can form a co-continuous structure by phase separation of a hydrophilic part and a hydrophobic part, such as a segmented block copolymer, improves the durability and proton conductivity of the polymer electrolyte membrane. Is preferable. Examples of such a segmented block copolymer include a copolymer of a hydrophilic segment having a salt of an anionic group and a hydrophobic segment having no anionic group and its salt. Such a segmented block copolymer can be obtained, for example, by polymerizing an oligomer constituting the segment directly or via another compound.
The molecular weight of the aromatic hydrocarbon electrolyte is not particularly limited, but it is preferable that the number average molecular weight measured by using gel permeation chromatography with polyethylene glycol as a standard is in the range of 10,000 to 500,000. If it is less than 10,000, the physical properties of the film may deteriorate. The larger the molecular weight, the better from the viewpoint of mechanical properties. However, when the molecular weight is too large, the concentration of the solvent solution of the aromatic hydrocarbon electrolyte is lowered when the polymer electrolyte membrane is produced using the aromatic hydrocarbon system. Inevitably, there may be a problem in removing the solvent.
The logarithmic viscosity of the aromatic hydrocarbon electrolyte is preferably in the range of 0.1 to 10.0 dL / g, and more preferably in the range of 0.3 to 5.0 dL / g. As a solvent for measuring the logarithmic viscosity, polar organic solvents such as N-methylpyrrolidone and N, N-dimethylacetamide can be generally used. When the solubility in these is low, concentrated sulfuric acid is used. It can also be measured.
The softening temperature of the aromatic hydrocarbon electrolyte is preferably 120 ° C. or higher, and more preferably 140 to 300 ° C.

(Method for producing aromatic hydrocarbon electrolyte)
The aromatic hydrocarbon electrolyte used in the present invention (preferably an aromatic hydrocarbon polymer having an acidic group, part of which forms a salt) may be produced by any method. For example, a method of converting an anionic group into a salt after introducing an anionic group into an aromatic hydrocarbon polymer, or an aromatic hydrocarbon polymer having an anionic group by polymerizing a monomer component having an anionic group And a method of converting this anionic group into a salt. The method for converting an anionic group into a salt is not particularly limited, and examples thereof include a method of immersing in an aqueous solution containing a cation.
Among the methods for introducing an anionic group into an aromatic hydrocarbon polymer, in particular, as a method for introducing a sulfonic acid group onto the aromatic ring of an aromatic hydrocarbon polymer, for example, an aromatic having a skeleton as described above A method of introducing a suitable sulfonating agent by reacting with a hydrocarbon polymer while appropriately selecting reaction conditions depending on the polymer may be mentioned. As such a sulfonating agent, for example, concentrated sulfuric acid and fuming sulfuric acid (for example, Solid State Ionics, 106, P219 (1998)) reported as an example of introducing a sulfonic acid group into an aromatic hydrocarbon polymer. ), Chlorosulfuric acid (eg, J. Polym. Sci., Polym. Chem., 22, P295 (1984)), sulfuric anhydride complex (eg, J. Polym. Sci., Polym. Chem., 22, P721 (1984)). ), J. Polym. Sci., Polym. Chem., 23, P1231 (1985)), and a sulfonating agent described in Japanese Patent No. 2884189. These sulfonating agents may be used alone or in combination of two or more.
Examples of a method for polymerizing a monomer component having an anionic group to obtain an aromatic hydrocarbon polymer having an anionic group include, for example, an aromatic having an anionic group (such as a sulfonic acid group or a phosphonic acid group). A method of polymerizing a diamine containing diamine and an aromatic tetracarboxylic dianhydride to obtain an anionic group-containing polyimide; a dicarboxylic acid containing an anionic group-containing aromatic dicarboxylic acid; an aromatic diamine diol or aromatic Polymerization of aromatic diaminedithiol and aromatic tetramine to obtain anionic group-containing polybenzoxazole, acidic group-containing polybenzthiazole and anionic group-containing polybenzimidazole; polymerization of aromatic dihalide and aromatic diol In obtaining polysulfone, polyethersulfone and polyetherketone, A method using an aromatic diol having an aromatic dihalide and an anionic group having an anion group and the like. Note that the degree of polymerization tends to be higher when an aromatic dihalide having an anionic group is used than when an aromatic diol having an anionic group is used, and the heat of the aromatic hydrocarbon polymer having an anionic group is increased. It is preferable because stability is increased.
The outline of the aromatic hydrocarbon electrolyte used in the present invention and the production method thereof have been described above. Below, the said polymer and the especially preferable aspect of the manufacturing method are demonstrated more concretely.

(Preferred example of aromatic hydrocarbon electrolyte)
The aromatic hydrocarbon electrolyte used in the present invention is preferably a compound having a constituent represented by the general formula (1) and having a sulfonic acid group as an anionic group.

However, X is a monovalent or divalent group, and any one of a nitrile group, an alkoxy group, an amino group, an amide group, an ester group, and a carboxyl group, and Z is any of an oxygen atom, a sulfur atom, a sulfone bond, and a direct bond Ar ′ represents a divalent aromatic group.

The component represented by the general formula (1) is particularly preferably a component represented by the following general formula (3).

However, Ar ′ represents a divalent aromatic group.

Moreover, it is preferable that the component containing an anionic group is a structural component shown by following General formula (2).

The aromatic hydrocarbon electrolyte of the present invention may contain structural units other than those represented by the general formulas (1) to (3). At this time, when a polymer other than the polymer having the structural unit represented by the general formulas (1) to (3) is used in combination, it is preferably 50% by mass or less with respect to 100% by mass of the total polymer. By setting it as 50 mass% or less, it can be set as the composition which utilized the characteristic of the aromatic hydrocarbon type electrolyte of this invention.

  The aromatic hydrocarbon electrolyte of the present invention includes the following general formula (4) as a constituent of the above general formula (2) and the following general formula (5) as a constituent of the above general formula (3). Particularly preferred are those containing a component represented by By having a biphenylene structure, the dimensional stability in the electrolytic solution is excellent, and the toughness of the film is also high.

X represents H or a monovalent or divalent cation species.
m and n represent the copolymerization ratio of the general formula (4) and the general formula (5), and m + n = 100, and preferably in the range of 25 ≦ m ≦ 55 and 45 ≦ n ≦ 75.

  The aromatic hydrocarbon electrolyte of the present invention can be polymerized by an aromatic nucleophilic substitution reaction containing compounds represented by the following general formulas (6) and (7) as monomers. Specific examples of the compound represented by the general formula (6) include 3,3′-disulfo-4,4′-dichlorodiphenyl sulfone, 3,3′-disulfo-4,4′-difluorodiphenyl sulfone, 3, 3'-disulfo-4,4'-dichlorodiphenyl ketone, 3,3'-disulfo-4,4'-difluorodiphenyl sulfone, and those whose sulfonic acid groups are converted to salts with monovalent cation species Can be mentioned. The monovalent cation species may be sodium, potassium, other metal species, various amines, or the like, but is not limited thereto. Examples of the compound represented by the general formula (7) include 2,6-dichlorobenzonitrile, 2,6-difluorobenzonitrile, 2,4-dichlorobenzonitrile, 2,4-difluorobenzonitrile, and the like. it can.

  Y represents a sulfonyl group or carbonyl group, X represents a monovalent or divalent cation species, and Z represents chlorine or fluorine. In the present invention, the above 2,6-dichlorobenzonitrile and 2,4-dichlorobenzonitrile are in an isomer relationship, and any of them is used, good ion conductivity, heat resistance, workability and dimensional stability. Can be achieved. The reason is considered that both monomers are excellent in reactivity and that the structure of the whole molecule is made harder by constituting a small repeating unit.

  In the above-described aromatic nucleophilic substitution reaction, various activated difluoroaromatic compounds and dichloroaromatic compounds can be used in combination with the compounds represented by the general formulas (6) and (7) as monomers. Examples of these compounds include 4,4′-dichlorodiphenyl sulfone, 4,4′-difluorodiphenyl sulfone, 4,4′-difluorobenzophenone, 4,4′-dichlorobenzophenone, decafluorobiphenyl, and the like. However, other aromatic dihalogen compounds, aromatic dinitro compounds, aromatic dicyano compounds and the like that are active in aromatic nucleophilic substitution can also be used.

In addition, Ar ′ in the structural component represented by the general formula (1) and Ar ′ in the structural component represented by the general formula (2) are generally the same as those described above in the aromatic nucleophilic substitution polymerization. It is a structure introduced from an aromatic diol component monomer used together with the compounds represented by the general formulas (6) and (7). Examples of such aromatic diol monomers include 4,4′-biphenol, bis (4-hydroxyphenyl) sulfone, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxy). Phenyl) propane, bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) butane, 3,3-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxy-3) , 5-dimethylphenyl) propane, bis (4-hydroxy-3,5-dimethylphenyl) methane, bis (4-hydroxy-2,5-dimethylphenyl) methane, bis (4-hydroxyphenyl) phenylmethane, bis ( 4-hydroxyphenyl) diphenylmethane, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9- (3-methyl-4-hydroxyphenyl) fluorene, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, hydroquinone, resorcin, bis (4-hydroxyphenyl) ketone, etc. Various aromatic diols that can be used for polymerization of polyarylene ether compounds by aromatic nucleophilic substitution reaction can also be used. These aromatic diols can be used alone, but a plurality of aromatic diols can be used in combination.

  When the aromatic hydrocarbon electrolyte of the present invention is polymerized by an aromatic nucleophilic substitution reaction, an activated difluoroaromatic compound and / or dichloroaromatic containing a compound represented by the above general formula (6) and general formula (7) A polymer can be obtained by reacting a compound with an aromatic diol in the presence of a basic compound. The polymerization can be carried out in the temperature range of 0 to 350 ° C., but is preferably 50 to 250 ° C. When the temperature is lower than 0 ° C., the reaction does not proceed sufficiently, and when the temperature is higher than 350 ° C., the polymer tends to be decomposed. The reaction can be carried out in the absence of a solvent, but is preferably carried out in a solvent. Examples of the solvent that can be used include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, diphenyl sulfone, sulfolane, and the like. And any solvent that can be used as a stable solvent in the aromatic nucleophilic substitution reaction. These organic solvents may be used alone or as a mixture of two or more. Examples of the basic compound include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, and the like, and those that can convert an aromatic diol into an active phenoxide structure may be used. It can use without being limited to. In the aromatic nucleophilic substitution reaction, water may be generated as a by-product. In this case, regardless of the polymerization solvent, water can be removed from the system as an azeotrope by coexisting toluene or the like in the reaction system. As a method for removing water out of the system, a water absorbing material such as molecular sieve can also be used. When the aromatic nucleophilic substitution reaction is carried out in a solvent, it is preferable to charge the monomer so that the resulting polymer concentration is 5 to 50% by mass. When the amount is less than 5% by mass, the degree of polymerization tends to be difficult to increase. On the other hand, when the amount is more than 50% by mass, the viscosity of the reaction system becomes too high, and the post-treatment of the reaction product tends to be difficult. After completion of the polymerization reaction, the solvent is removed from the reaction solution by evaporation, and the residue is washed as necessary to obtain the desired polymer. In addition, the polymer can be obtained by precipitating the polymer as a solid by adding the reaction solution in a solvent having low polymer solubility, and collecting the precipitate by filtration.

The aromatic hydrocarbon electrolyte of the present invention may be a block polymer composed of the components of the above general formula (1) and general formula (2). It is preferable to use a block polymer because it has excellent dimensional stability in the electrolytic solution and improves the vanadium ion permeation suppression effect due to the microphase separation structure of the hydrophilic segment and the hydrophobic segment.

The block polymerization comprising the components of the general formula (1) and the general formula (2) can be synthesized by any known method. It can synthesize | combine by couple | bonding the oligomer which becomes a hydrophobic segment which consists of the hydrophilic segment which consists of the said General formula (1), and the said General formula (2) previously synthesize | combined with a coupling agent. As an example thereof, there can be mentioned a method in which a hydroxyl group-terminated oligomer is bonded with a perfluoroaromatic compound such as decafluorobiphenyl. In this case, it is preferable that the molar ratio of the perfluoroaromatic compound such as decafluorobiphenyl and the oligomers of both be close to 1.

In addition, the terminal group of any of the oligomers that have been synthesized in advance and become hydrophilic and hydrophobic segments is modified with a highly reactive group such as the above-mentioned perfluoroaromatic compound such as decafluorobiphenyl. Alternatively, it can be synthesized by reacting the other oligomer. Further, in the above reaction, the oligomer may be used after being purified and isolated after synthesis, may be used as it is in the synthesized oligomer solution, or the purified and isolated oligomer may be used as a solution. . The oligomer to be purified and isolated may be any oligomer, but the oligomer forming the hydrophobic segment is easier to synthesize. In the case of a method in which one end group of an oligomer to be a hydrophilic and hydrophobic segment synthesized in advance is modified with a highly reactive group and the other oligomer is reacted, The other oligomer is preferably reacted in an equimolar amount, but in order to prevent gelation due to a side reaction during the reaction, it is preferable to keep the modified oligomer slightly in excess. The degree of excess varies depending on the oligomer molecular weight and the molecular weight of the target polymer, but is preferably in the range of 0.1 to 50 mol%, more preferably in the range of 0.5 to 10 mol%. In addition, the hydrophobic segment is preferably modified with a highly reactive group. Depending on the structure of the hydrophilic segment, the modification reaction may not proceed well.

  The aromatic hydrocarbon electrolyte of the present invention can be used as a simple substance, but can also be used as a composition in combination with other polymers. Examples of these polymers include polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, polyamides such as nylon 6, nylon 6,6, nylon 6,10 and nylon 12, polymethyl methacrylate and polymethacrylate. Acrylate resins such as polymethyl acrylate, polyacrylic acid esters, polyacrylic acid resins, polymethacrylic acid resins, polyethylene, polypropylene, various polyolefins including polystyrene and diene polymers, polyurethane resins, cellulose acetate, Cellulosic resins such as ethyl cellulose, polyarylate, aramid, polycarbonate, polyphenylene sulfide, polyphenylene oxide, polysulfone, polyether Heat curing of aromatic polymers such as sulfone, polyether ether ketone, polyether imide, polyimide, polyamide imide, polybenzimidazole, polybenzoxazole, polybenzthiazole, epoxy resin, phenol resin, novolac resin, benzoxazine resin There are no particular restrictions on the conductive resin. A composition with a basic polymer such as polybenzimidazole or polyvinylpyridine can be said to be a preferable combination for improving polymer dimensionality. If a sulfonic acid group is further introduced into these basic polymers, the composition The workability of the product becomes more preferable. When used as these compositions, the aromatic hydrocarbon electrolyte of the present invention is preferably contained in an amount of 50% by mass or more and less than 100% by mass of the entire composition. More preferably, it is 70 mass% or more and less than 100 mass%. When the content of the aromatic hydrocarbon electrolyte of the present invention is less than 50% by mass of the entire composition, the sulfonic acid group concentration of the ion conductive membrane containing this composition is lowered, and good ion conductivity is obtained. In addition, the unit containing a sulfonic acid group tends to be a discontinuous phase and the mobility of ions to be conducted tends to be lowered. In addition, the composition of the present invention, if necessary, for example, an antioxidant, a heat stabilizer, a lubricant, a tackifier, a plasticizer, a crosslinking agent, a viscosity modifier, an antistatic agent, an antibacterial agent, an antifoaming agent, Various additives such as a dispersant and a polymerization inhibitor may be included.

(Solvents for aromatic hydrocarbon electrolytes)
In the present invention, the solvent used in the polymerization and film forming step is not particularly limited as long as it can uniformly dissolve or disperse the aromatic hydrocarbon electrolyte, and the structure of the aromatic hydrocarbon electrolyte is not limited. However, it is preferably a polar solvent, and more preferably an aprotic polar solvent. Examples of the aprotic polar solvent include N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, N-morpholine-N-oxide, and hexamethylene. Examples include phosphonamide, dimethyl sulfoxide, sulfolane, γ-butyrolactone, and diphenyl sulfone. In particular, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone and dimethyl sulfoxide are preferable. These solvents may be used alone or in combination of two or more. The boiling point of the solvent is preferably in the range of 100 to 300 ° C. If it is lower than 100 ° C., the form may be deteriorated during film formation, which is not preferable. If it exceeds 300 ° C., a large amount of energy may be required for the production of the polymer electrolyte membrane, and it may be difficult to control the solvent content in the aromatic hydrocarbon electrolyte membrane within an appropriate range.

(Solid content concentration of aromatic hydrocarbon electrolyte solution)
The solid content concentration of the aromatic hydrocarbon electrolyte solution can be appropriately determined depending on the molecular weight of the aromatic hydrocarbon electrolyte, the temperature at the time of casting, and the like, specifically 1.0 to 30% by mass. It is necessary to be in the range of 1.5 to 25% by mass, and more preferably 2.0 to 20% by mass. If it is less than 1.0% by mass, it may take time to remove the solvent in the subsequent step, and the quality of the film may be lowered, or the glass fiber substrate may not be sufficiently filled with the aromatic hydrocarbon electrolyte. . If it exceeds 30% by mass, the viscosity of the solution becomes too high to impregnate the glass fiber substrate, and the air remaining in the glass fiber substrate adversely affects the properties of the composite membrane.

(Viscosity of aromatic hydrocarbon electrolyte solution)
The viscosity of the aromatic hydrocarbon-based electrolyte solution can be appropriately determined depending on the degree of impregnation into the glass fiber substrate, and needs to be 2.0-200000 mPa · s, and 5.0-150,000 mPa · s. Is more preferable, and 10 to 100,000 mPa · s is more preferable. If it is less than 2.0 mPa · s, the impregnated solution will flow down from the glass fiber base material, so that the glass fiber base material cannot be sufficiently filled with the aromatic hydrocarbon-based electrolyte. The fiber substrate is no longer impregnated and the air remaining in the glass fiber substrate adversely affects the properties of the composite membrane.

(Types of glass fiber substrate)
As an effect of the glass fiber base material in the present invention, in addition to the reinforcing effect of the aromatic hydrocarbon electrolyte due to the strength of the glass fiber itself, the glass fiber has the effect of suppressing the dimensional change due to the swelling and drying of the aromatic hydrocarbon electrolyte. Can be mentioned. These effects are the ability to suppress stress concentration due to dimensional changes between the assembled jig and the membrane, in addition to the ability to directly control the breakage of airflow and liquid flow when the ion exchange membrane is incorporated into each device. This is a very important requirement for improving the durability of the ion exchange membrane during use.
Any kind of glass fiber base material may be used as long as it has a communication hole through which a substance can pass on the surface opposite to one surface. Specifically, glass yarn, glass cloth, glass paper, glass grid, etc. It is done.

(Strength of glass fiber substrate)
The strength of the glass fiber substrate is an important requirement of the present invention. Specifically, the strength of the glass fiber base material needs to be 0.4 MPa or more, preferably 0.7 MPa or more, and more preferably 1.0 MPa or more. If the strength is less than 0.4 MPa, since the reinforcing effect of the aromatic hydrocarbon electrolyte of the glass fiber substrate is small, it is compounded by the stress caused by the swelling of the polymer by water or ionic aqueous solution or the stress applied when the liquid or gas flows The film is broken, and the effect of improving durability is reduced.

(Glass fiber substrate thickness)
According to the production method of the present invention, a composite film corresponding to various thicknesses of a glass fiber substrate can be produced with good form and good productivity. Specifically, it is necessary to prepare a composite membrane having a thickness of 10 μm or more, and a composite membrane having a good shape even if it is a glass fiber substrate of 10 μm or less (thinner 7.5 μm or less). Can be manufactured with good productivity. The upper limit of the thickness of the glass fiber substrate is not particularly limited, but is preferably 500 μm or less, more preferably 400 μm or less, and even more preferably 300 μm or less.

(Material of glass fiber substrate)
The material of the glass fiber base material is an important requirement for enhancing the durability of the composite membrane. Specifically, even E glass, which is usually used for glass fibers, can achieve a sufficient durability improvement due to the reinforcement effect due to the combination with the aromatic hydrocarbon polymer electrolyte. However, when the sulfonic acid group possessed by the aromatic hydrocarbon polymer electrolyte is used as a free acid or when an acidic electrolyte solution is used such as a redox flow battery, borosilicate glass fibers such as C glass and T glass, Further high durability can be obtained by using glass fiber having high acid resistance.

(Method of impregnating glass fiber substrate with aromatic hydrocarbon electrolyte solution)
As a method for impregnating the glass fiber substrate with the aromatic hydrocarbon electrolyte solution, any method may be used as long as the aromatic hydrocarbon polymer electrolyte can be fixed in the glass fiber substrate. For example, a method of immersing a glass fiber substrate in an aromatic hydrocarbon-based electrolyte solution, a method of casting an aromatic hydrocarbon-based electrolyte solution on a support first, and placing a glass fiber substrate thereon There is a method of placing a glass fiber substrate on an aromatic hydrocarbon electrolyte solution cast on a support, and casting an aromatic hydrocarbon electrolyte solution from the glass fiber substrate, but the method is limited to this. It is not a thing. Furthermore, it is also possible to change the type of the aromatic hydrocarbon electrolyte solution for a method in which the immersion and casting are repeated many times, or when the immersion and casting are performed a plurality of times. Furthermore, after dipping and casting, it is of course possible to carry out operations such as decompression and pressurization for further penetration of the aromatic hydrocarbon electrolyte solution into the glass fiber substrate.

(Solvent removal method)
In this step, the method of removing the solvent from the impregnated film is not particularly limited, and examples thereof include a method of heating the cast film and evaporating the solvent. At this time, the heating temperature of the cast film is preferably 400 ° C. or less, more preferably 350 ° C. or less, and further preferably 330 ° C. or less. When the heating temperature exceeds 400 ° C, the solvent removal efficiency is improved, but the polymer electrolyte membrane is obtained by decomposition or alteration of the solvent or aromatic hydrocarbon electrolyte even in a short time, or by rapid drying deformation May deteriorate (deterioration of quality). Moreover, about the minimum of heating temperature, 50 degreeC is preferable. If the heating temperature is less than 50 ° C., it may be difficult to remove the solvent sufficiently. The heating method can be performed by any known method such as hot air, infrared rays, and microwaves. Moreover, you may carry out in inert gas atmosphere, such as nitrogen.

(Removal of solvent with poor solvent)
In the present invention, it is possible to extract the solvent in the membrane with a poor solvent of an aromatic hydrocarbon electrolyte that is mixed with the solvent after the composite membrane is heated to evaporate the solvent to a certain amount. As a poor solvent, what is necessary is just to use a suitable thing according to the kind of film | membrane and the solvent used at the casting process. For example, water, alcohol, ketone, ether, low molecular hydrocarbon, halogen-containing solvent and the like can be mentioned. When the solvent used in the impregnation step is miscible with water, it is preferable to use water as the poor solvent.
The method for extracting the solvent in the film with a poor solvent is not particularly limited, but it is preferable to carry out so that the poor solvent uniformly contacts the film. For example, a method of immersing the film in a poor solvent and a method of applying or spraying the poor solvent onto the film are exemplified. These methods may be performed two or more times or in combination.
The temperature of the poor solvent is preferably not less than the melting point and not more than the boiling point of the poor solvent used. When the poor solvent is water, it is preferably in the range of 10 to 70 ° C, more preferably 20 to 50 ° C. When the temperature is high, the solvent removal efficiency is improved, but the form and performance of the film may be lowered. Further, when the temperature is low, the solvent removal efficiency is lowered, and the productivity may be lowered.
In this invention, it is preferable that the content rate of the solvent in the film | membrane obtained through the extraction operation by the said poor solvent is 0.01 to 3 mass%. In the region of less than 0.01% by mass, as in the case of the above heating, the amount of the solvent itself is small, so that the above effect is not substantially enhanced, but a great amount of time is consumed to further reduce the trace amount of solvent. Is necessary and not realistic. If it is larger than 3% by mass, the durability of the film may be lowered, for example, the swelling property is increased. The content of the solvent in the film after the extraction operation is more preferably 2% by mass or less, and further preferably 1% by mass or less.
The solvent content of the film can be measured by any known method. For example, a method in which an aromatic hydrocarbon electrolyte is dissolved in another appropriate solvent and the solvent is quantified by liquid chromatography or gas chromatography, or the solvent is extracted with an appropriate extraction solvent such as water and quantified. Method, NMR measurement of the film, quantification from the integral value of the peak derived from the solvent and the peak derived from the aromatic hydrocarbon electrolyte, and the absorption spectrum of the film such as infrared, near infrared, ultraviolet, and visible In addition, a method of determining from the absorbance of the solvent component, a method of determining by mass reduction due to evaporation of the solvent during heating, etc. by thermogravimetry (TGA) can be used. The measurement may be performed during the manufacturing process, or may be performed off-line by sampling from the process so that the content does not change.

(Step of bringing the ion exchange membrane into contact with the acidic solution)
Depending on the use of the ion exchange membrane, it is of course possible to use the composite membrane from which the above solvent has been removed by converting an anionic group into a proton by bringing it into contact with an acidic solution having a pKa of 3 or less. The acidic solution having a pKa of 3 or less used in this step is at least one selected from the group of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, perchloric acid, methanesulfonic acid, trifluoroacetic acid, sulfonimide, oxo acid and the like. An aqueous solution in which an acidic component of a seed is dissolved is mentioned. When the acidic group of the polymer electrolyte is a sulfonic acid group, the acidic component is preferably sulfuric acid, hydrochloric acid, methanesulfonic acid, or trifluoroacetic acid, and more preferably sulfuric acid.

(Concentration of acidic solution)
The concentration of the acidic component in the acidic solution is not particularly limited, but it is preferable to adjust so that the pKa of the acidic solution is equal to or smaller than the salt of the acidic group of the aromatic hydrocarbon electrolyte. For example, when the acidic group salt of the aromatic hydrocarbon electrolyte is a sulfonic acid group salt, the concentration of the acidic component is preferably in the range of 1 to 75% by mass. If the concentration is less than 1% by mass, a large amount of acidic solution is required for conversion to protons, which may cause a problem in productivity. When the concentration exceeds 75% by mass, the dissociation degree of the acidic component in the acidic solution may decrease, and the conversion efficiency may decrease.

(Contact method between acidic solution and ion exchange membrane)
The method for converting the salt of the acidic group of the aromatic hydrocarbon electrolyte in the composite membrane into protons using the acidic solution is not necessarily limited, so that the acidic solution contacts the membrane uniformly multiple times. Any method can be used. For example, there are a method of immersing the membrane in an acidic solution and a method of applying or spraying the acidic solution on the membrane, and all methods can be selected from a single method or a combination method for each contact. Among these, a preferable method is a method of continuously immersing the composite membrane in two or more acidic solution tanks from the viewpoint of suppressing the amount of the acidic solution used, and a more preferable method is two or more acidic solutions. The composite membrane is continuously immersed in the tank, and a new acidic solution that does not contain salt is supplied to the acidic solution tank on the most downstream side in the order of immersion so that the tank overflows. There is a method in which an acidic solution overflowing from the most upstream tank is removed as waste liquid.

(Step of washing the ion exchange membrane after contact with the acidic solution)
The acid-treated membrane that has passed through the step of bringing the ion exchange membrane into contact with the acidic solution described above then passes through a washing step that removes free acid in the membrane.
The cleaning liquid used in this step is not particularly limited as long as water is a main component (preferably 80% or more, more preferably 90% or more, and further preferably 95% or more), and the pH is within a predetermined range. . For example, the solvent may contain at least one poor solvent for the polymer electrolyte membrane that can dissolve acidic components, such as alcohol, ketone, ether, low-molecular hydrocarbon, and halogen-containing solvent. When the cleaning liquid contains water as a main component, the process can proceed to the next step without any acidic component remaining in the film. In other words, it is possible to avoid equipment and environmental burden due to elution of acidic components in the subsequent steps. In the cleaning method in this cleaning step, the membrane is preferably brought into contact with a cleaning solution. The method of contacting the cleaning liquid is not particularly limited, such as a method of spraying the cleaning liquid directly using a shower or the like, a method of immersing in the cleaning liquid, and the like. Further, the contact with the cleaning liquid may be repeated. At this time, if the cleaning solution contains a salt, the acidic group may be converted back to the metal salt. Therefore, it is desirable to use at least a cleaning solution that has been subjected to ion removal treatment such as ion-exchanged water.
The temperature of the cleaning liquid is preferably 20 to 60 ° C. (more preferably 20 to 40 ° C.). When the cleaning solution is brought into contact with the membrane a plurality of times, the temperature may be different or the same for each contact time.
When the temperature of the cleaning liquid is lower than 20 ° C., the removal efficiency of the acidic component is lowered and the productivity is lowered. When the temperature is higher than 60 ° C., the swelling of the polymer electrolyte membrane increases, the quality deteriorates due to membrane deformation, and further, the membrane deformation site propagates, and the polymer electrolyte membrane may peel from the support.
The content of acidic components in the ion exchange membrane is preferably 1% by mass or less, more preferably 0.1% by mass or less of the aromatic hydrocarbon electrolyte by washing with the washing liquid. If the content of the acidic component is large, the acidic component may be eluted, causing corrosion and chemical damage.
The content rate of the acidic component in the ion exchange membrane can be measured by any known method. For example, the content rate can be measured by extracting an elution component from an ion exchange membrane with a solvent such as water and quantifying an acidic component in the solvent. Water is preferably used for extraction, and water with few impurities such as ion exchange water and ultrapure water is preferable. For extraction, methods such as immersion, boiling, ultrasonic treatment, and Soxhlet extraction can be used. The acidic component can be quantified by methods such as neutralization titration with alkali, pH measurement of the extract, ion chromatography, liquid chromatography, gas chromatography and the like.

(Drying process)
If an acidic solution or a cleaning solution remains in the ion exchange membrane obtained through the cleaning process, the evaporation or leaching of these may cause problems such as morphological defects such as wrinkles or irregularities, adhesion, etc. Becomes higher. For this reason, it is preferable to reduce the amount of the solvent remaining in the ion exchange membrane. For example, when water is used as the solvent of the acidic solution or the solvent of the cleaning solution, the solvent content (water content) in the composite is 5 to 30% by mass, more preferably 7 to 20% by mass of the aromatic hydrocarbon electrolyte. It is preferable. The method for drying the ion exchange membrane is not particularly limited, and examples thereof include air drying at an appropriate temperature, heating with infrared rays or far infrared rays, and distillation under reduced pressure. Although a drying temperature is not specifically limited, For example, it can carry out at 20-50 degreeC.
The solvent content (for example, water content) of the ion exchange membrane can be measured by any known method, and is not limited. For example, a method using an infrared moisture meter, a Karl Fischer moisture meter , Method of determining the solvent content (moisture content) by measuring the weight at the time of solvent containing (water containing) and absolutely dry, the solvent content (water content) by thermogravimetric analysis by weight reduction during heating For example.

(Ion exchange membrane shape)
The shape of the ion exchange membrane obtained by the production method of the present invention is not particularly limited, and may be any form such as a sheet or a roll. In addition, when a support is used when producing an ion exchange membrane, the support may not be peeled off, and after production, the composite membrane may be laminated with another support by peeling off from the support. Is possible.

(Handling of ion exchange membrane)
The handleability of the ion exchange membrane is a very important factor from the viewpoint of reducing labor during use and improving the yield. Specifically, the handleability value determined in the following examples is preferably 2 or more, and higher if 3 or more.

(Suppression of water swelling of ion exchange membrane)
The suppression of the area swelling degree of the composite membrane means that the composite glass fiber substrate prevents the aromatic hydrocarbon electrolyte from swelling with the redox flow battery solution, and stress concentration at the boundary with the separator and tearing due to the liquid flow. Very important.
Specifically, the area swelling rate of the ion exchange membrane defined in the following examples is determined for each of the membrane composited with glass fiber and the membrane not composited,
The ratio obtained by (area swelling ratio of composite film) / (area swelling ratio of non-composite film) is essential to be less than 1, preferably 0.9 or less, and more preferably 0.8 or less.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to these examples, and can be implemented with appropriate modifications within a range that can be adapted to the above and the gist described below. These are all included in the technical scope of the present invention. In the following examples and comparative examples, “parts” and “%” mean parts by mass and mass%, respectively. In addition, (Table 1) illustrates the configuration of the redox flow battery.

  First, the logarithmic viscosity of aromatic hydrocarbon electrolytes (membranes) and polymer electrolytes (membranes) produced by Examples and Comparative Examples, residual solvent amount, cation substitution rate measurement method, moisture content evaluation method, Next, specific implementation and comparative examples will be described.

(Amount of ionic group of aromatic hydrocarbon electrolyte)
Moisture of the ion exchange membrane to be measured is wiped off with a filter paper, left in a room at 23 ° C. and 50% RH for 1 hour, dissolved in deuterated dimethyl sulfoxide, and integrated using a Varian Varian 400-MR. ¹ H-NMR spectrum was measured 128 times at 25 ° C. The ionic group amount (meq / g) of the aromatic hydrocarbon electrolyte membrane was calculated from the integral value of the peak with respect to the aromatic hydrocarbon electrolyte previously assigned. For the calculation of the ionic group amount of the composite membrane,
The weight of the glass fiber was subtracted from the weight of the sample used to calculate the amount of ionic groups of the polymer electrolyte alone. Moreover, about what substituted the anion of the ionic group with the cation, it calculated | required by measuring the amount of ionic groups after converting a sample into a free acid by contact with the said acidic solution.

(Cation substitution rate of aromatic hydrocarbon electrolytes and ionic groups of the membrane)
Quantification of Na and K in the polymer electrolyte (membrane) was performed by inductively coupled plasma emission spectrometry. The cation substitution rate was determined from the amount of ionic groups of the polymer electrolyte (membrane), the amount of Na and the amount of K determined by the ¹ H-NMR analysis.
Cation substitution rate (mol%)
= {(C _Na /23.0+C _K /39.1)÷1000}÷C _I × 100
C _Na represents the Na content (mg / kg), C _K represents the K content (mg / kg), and C _I represents the acidic group content (mmol / g).
In addition, when calculating | requiring the cation substitution rate in a composite film, the contribution of a glass fiber base material was subtracted and the value of aromatic hydrocarbon type electrolyte alone was used.

(Log viscosity of aromatic hydrocarbon electrolyte)
The aromatic hydrocarbon electrolyte was dissolved in N-methylpyrrolidone at a concentration of 0.5 g / dL, and the viscosity was measured using a Ubbelohde viscometer in a constant temperature bath at 30 ° C., and the logarithmic viscosity ln [ta / tb ] / C (ta is the drop time of the sample solution, tb is the drop time of the solvent alone, and c is the polymer concentration of the sample solution [unit: g / dL]).

(Measurement of residual solvent)
Moisture of the aromatic hydrocarbon electrolyte membrane to be measured is wiped off with a filter paper, left in a room at 23 ° C. and 50% RH for 1 hour, dissolved in deuterated dimethyl sulfoxide, and Varian 400-MR manufactured by Varian is used. The ¹ H-NMR spectrum was measured at 25 ° C. using 128 times of integration. The residual solvent amount with respect to the aromatic hydrocarbon electrolyte was calculated from the integral value of the peak with respect to the aromatic hydrocarbon electrolyte and the solvent previously assigned.

(Strength of glass fiber substrate)
The glass fiber substrate was conditioned for 24 hours in an environment of 23 ° C. and 50% relative humidity, and then evaluated according to JIS K 7127.

(Handling of ion exchange membrane)
The work required when placing a plate of 25 cm long and 25 cm wide on a glass plate and then transferring the membrane alone onto a glass plate placed 1 m away and the form of the transferred ion exchange membrane are shown below. Graded.
1: The film carried with one hand or both hands stuck together and could not be corrected. 2: The film carried with one hand stuck together and could not be modified.
The film carried with both hands would stick, but could be corrected.
3: The film carried with one hand sticks, but can be corrected.
The film carried with both hands did not stick and only some wrinkles and warping occurred.
4: Can be carried with one hand, only some wrinkles and warping occurred.
5: Can be carried with one hand, no problem in form.

(Area swelling rate of ion exchange membrane)
After conditioning the ion exchange membrane at 23 ° C. and 50% relative humidity for 24 hours, draw a square of 50 mm square, and then hold it at 23 ° C. for 24 hours in pure water, then lift the composite membrane to quickly remove the surface moisture The length was measured and the areas were compared, and the area swelling rate was calculated.

(Redox flow battery characteristics)
The ion exchange membrane was sandwiched between carbon electrode materials (XF30A manufactured by Toyobo Co., Ltd.) to assemble a cell as shown in FIG. A small cell having an electrode area of 10 cm ² of 10 cm in the vertical direction (liquid passing direction) and 1 cm in the width direction is made, and charging / discharging is repeated at a constant current density, and the current efficiency, cell resistance, energy efficiency, and voltage efficiency are as follows. Calculated as follows. Moreover, 3 mol / l sulfuric acid aqueous solution of 2 mol / l vanadium oxysulfate was used for the positive electrode electrolyte, and 3 mol / l sulfuric acid aqueous solution of 2 mol / l vanadium sulfate was used for the negative electrode electrolyte. The amount of the electrolytic solution was excessively large with respect to the cell and the piping. The liquid flow rate was 6.2 ml per minute, and the measurement was performed at 30 ° C.

(Redox flow battery durability (cycle count))
A constant current charge up to 1.6 V is performed with a current density of 100 mA / cm 2 per electrode geometric area (1600 mA overall) for a 1.0 V cell, and then the current density is increased from 1.6 V to 100 mA / cm 2 per electrode geometric area. One cycle is defined as the time when constant current discharge is performed (1600 mA in total) and 1.0V is reached.
This cycle is repeated until charge / discharge is impossible, and the number of cycles at that time is defined as redox flow battery durability.

Example 1
3,3′-disulfo-4,4′-dichlorodiphenylsulfone disodium salt (abbreviation: S-DCDPS) 50.00 g (0.1012 mole), 2,6-dichlorobenzonitrile (abbreviation: DCBN) 22.215 g ( 0.1288 mole), 42.846 g (0.2299 mole) of 4,4′-biphenol, 34.957 g (0.2529 mole) of potassium carbonate, and 26.10 g of molecular sieves were weighed into a 1 L four-necked flask and flushed with nitrogen. . After adding 300 ml of NMP and stirring at 150 ° C. for 1 hour, the reaction was continued by raising the reaction temperature to 195-200 ° C. and sufficiently increasing the viscosity of the system (about 5 hours). After standing to cool, the precipitated molecular sieve was removed and the mixture was precipitated in water as a strand. The obtained polymer was washed in boiling water for 1 hour and then dried. The logarithmic viscosity of the polymer was 1.25, and m = 44 in the above structural formula.

10 g of the polymer was dissolved in 30 g of NMP to prepare a 25% by weight solution, which was applied onto a PET film with an applicator having a gap of 32 μm. Next, C glass paper (thickness 50 μm) was placed on the solution after application and impregnated from the lower surface. Then, the solution was applied again from above with an applicator having a gap of 352 μm, and impregnation from the upper surface. Went. The coated product was dried on a hot plate at 130 ° C. for 30 minutes, then immersed in pure water for 3 hours for 1 hour to remove the solvent, then air-dried and peeled from the PET film to obtain a composite film having a thickness of 54 μm. The handleability of the obtained composite membrane was 4, and high handleability could be confirmed.
When the redox flow battery durability of this composite was evaluated, the number of cycles was 1900 times, and very high durability could be confirmed.

(Example 2)
9 g of the polymer of Example 1 was dissolved in 41 g of NMP to prepare an 18% by weight solution, which was applied onto a PET film with an applicator having a gap of 82 μm. Next, 4 g of the polymer of Example 1 was dissolved in 28 g of NMP to prepare a 12.5 wt% solution, which was then put into a vat to make an impregnation solution, and an E glass cloth (thickness 15 μm, plain weave) obtained by purchase was used for impregnation. After immersing in the solution and squeezing between two rolls, it is placed on a PET film. From this, 18% by weight of the solution is applied again with an applicator having a gap of 482 μm, and at 80 ° C. for 30 minutes, 130 ° C. After drying for 30 minutes, remove the solvent by immersion in pure water for 1 hour and 3 times for 1 hour, soak in 2M sulfuric acid aqueous solution for 1 hour and 2 times for acid conversion, and then wash by immersion in pure water for 30 minutes and 5 times. After air drying and peeling from the PET film, a 51 μm thick composite was obtained. The handleability of the obtained composite membrane was 4, and high handleability could be confirmed.
When the redox flow battery durability of this composite was evaluated, the cycle number was 1250 times, and very high durability could be confirmed.

(Example 3)
12 g of the polymer of Example 1 was dissolved in 188 g of NMP to prepare a 6% by weight solution, which was placed in a plastic vat to make an impregnation solution. Next, a plain weave C glass cloth having the same thickness as that used in Example 2 was dipped in the impregnation solution, pulled up, and dried at 90 ° C. for 10 minutes three times to obtain a composite film having a thickness of 53 μm. .
This composite membrane was further immersed in a 2M sulfuric acid aqueous solution for 1 hour twice to perform acid conversion, further immersed in pure water for 30 minutes, washed 5 times, and then air-dried to obtain a composite membrane having a thickness of 51 μm. The handleability of the obtained composite membrane was 5, and very high handleability could be confirmed.

(Comparative Example 1)
10 g of the polymer of Example 1 was dissolved in 30 g of NMP to prepare a 25 wt% solution, which was applied to a thickness of 170 μm on a PET film and dried on a hot plate at 130 ° C. for 30 minutes. It was immersed in pure water for 1 hour and 3 times to remove the solvent, then air-dried and peeled from the PET film to obtain a single film having a thickness of 30 μm. The handleability of the obtained composite membrane was 3.
When the redox flow battery durability of this single membrane was evaluated, the number of cycles was 550.

(Comparative Example 2)
The film of Comparative Example 1 was removed from the solvent and then immersed in a 2M aqueous sulfuric acid solution for 1 hour and twice for acid conversion, further immersed in pure water for 30 minutes and washed 5 times, then air-dried, peeled off from the PET film, and 30 μm thick. A membrane was obtained. The IEC determined by titration of this membrane was 2.03.
Moreover, the handleability of the obtained composite membrane was 3.
When the redox flow battery durability of this single membrane was evaluated, the number of cycles was 230.

(Comparative Example 3)
The composite film was obtained by sandwiching the film of Comparative Example 1 from both sides with the C glass paper used in Example 1. The handleability of the resulting composite was 3. When the redox flow battery durability of this composite was evaluated, the number of cycles was 550.

  The ion exchange membrane of the present invention can greatly improve durability and handleability during use by combining a glass fiber substrate and an aromatic hydrocarbon-based electrolyte. It greatly contributes to the industry as a means for providing a polymer electrolyte membrane used in batteries, fuel cells, and the like.

DESCRIPTION OF SYMBOLS 1 ... Current collecting plate 2 ... Spacer 3 ... Ion exchange membrane 4a, b ... Liquid passage 5 ... Electrode material 6 ... Positive electrode liquid tank 7 ... Negative electrode liquid tank 8, 9 ... Pump

Claims (11)

A composite membrane containing an aromatic hydrocarbon polymer electrolyte having an anionic group in a glass fiber substrate having a strength of 0.4 MPa or more, wherein the aromatic hydrocarbon polymer electrolyte is a solvent And the thickness of the composite film is 10 μm or more,
The ion-exchange membrane characterized in that the aromatic hydrocarbon-based polymer electrolyte includes a constituent represented by the general formula (1) and has at least a sulfonic acid group as the anionic group.
However, X is a monovalent or divalent group, and any of a nitrile group, an alkoxy group, an amino group, an amide group, an ester group, and a carboxyl group, and Z is any of an oxygen atom, a sulfur atom, a sulfonyl group, and a direct bond Ar ′ represents a divalent aromatic group. The aromatic hydrocarbon polymer electrolyte further includes a constituent represented by the general formula (2), and the general formula (1) is a constituent represented by the general formula (3). The ion exchange membrane according to claim 1.
Here, Ar represents a divalent aromatic group, Z represents a sulfonyl group or a carbonyl group, and X represents H or a monovalent or divalent cation species.

However, Ar ′ represents a divalent aromatic group. In the electrolyte composite membrane, when the total amount of anionic groups of the aromatic hydrocarbon polymer electrolyte is 100 mol%, 80 mol% or more of the anionic groups are alkali metal or alkaline earth metal cations. The ion exchange membrane according to claim 1, wherein a salt is formed. The ion exchange membrane according to claim 3, wherein the cation is one or more selected from the group consisting of sodium ion, potassium ion, cesium ion, magnesium ion, and calcium ion.   In the electrolyte composite membrane, when the total amount of anionic groups in the aromatic hydrocarbon polymer electrolyte is 100 mol%, 90 mol% or more of the anionic groups are free acids. The ion exchange membrane according to claim 1.   The ion exchange according to any one of claims 1 to 5, wherein a content of the sulfonic acid group in the aromatic hydrocarbon polymer electrolyte is in a range of 0.1 to 5.0 meq / g. film.   The said ion exchange membrane consists of a composition which contains 50-100 mass% of aromatic hydrocarbon type polymer electrolytes in any one of Claim 1, 2, The one in any one of Claims 1-6 characterized by the above-mentioned. The ion exchange membrane as described.   The ion exchange membrane according to any one of claims 1 to 7, wherein the glass fiber substrate is one of glass yarn, glass cloth, glass paper, and glass grid.   The method for producing an ion exchange membrane according to any one of claims 1 to 8, wherein a glass fiber substrate is impregnated with a solution obtained by dissolving an aromatic hydrocarbon polymer electrolyte having an anionic group in a solvent. Thereafter, the solvent is removed to obtain a composite membrane having a thickness in the range of 5 to 300 μm.   A redox flow battery using the ion exchange membrane according to claim 1.   A fuel cell comprising the ion exchange membrane according to claim 1, 2 or 5.