WO2013183584A1

WO2013183584A1 - Ion permeable diaphragm

Info

Publication number: WO2013183584A1
Application number: PCT/JP2013/065342
Authority: WO
Inventors: 樋口　浩之; 隆史熊野; 健郎井上; 網野　一郎; 正也西川原; 島谷　俊一; 敦大門
Original assignee: 日東電工株式会社
Priority date: 2012-06-08
Filing date: 2013-06-03
Publication date: 2013-12-12
Also published as: JP2014012889A

Abstract

Provided is an ion permeable diaphragm that has excellent characteristics generally required for ion permeable diaphragms to be used in alkaline water electrolysis [i.e., (1) being ion permeable, (2) having sufficient mechanical strength and chemical stability against alkaline water, (3) being gas-impermeable through the diaphragm, and (4) being capable of preventing short-circuit between electrodes] and, at the same time, is capable of preventing an increase in voltage caused by gas sticking to the diaphragm surface, said gas being generated from electrodes during electrolysis. The ion permeable diaphragm according to the present invention is provided with a microporous film and at least one kind of metal oxide selected from titanium oxide and zirconium oxide sticks to said microporous film.

Description

Ion-permeable membrane

The present invention relates to an ion permeable diaphragm.

Conventionally, an energy composition centered on fossil fuels has been established, but in addition to limited resources, fossil fuels are limited in areas where they can be produced. The need for use is increasing. In addition, power generation using natural energy cannot always generate power when necessary, and the importance of power storage for temporarily storing the obtained power is increasing. As one of the storage methods, there is a method using a secondary battery, but there is a problem that increasing the capacity of the secondary battery is expensive. Against this background, a method of electrolyzing water and converting electric power into hydrogen and storing it has been attracting attention, coupled with technological progress in fuel cells that can reconvert hydrogen into electricity with high efficiency. As an industrial production method of hydrogen, there is a water electrolysis method using a polymer electrolyte. However, this uses a noble metal such as platinum as a catalyst, which causes a problem of high cost. Therefore, the alkaline water electrolysis method is expected as a method for stably obtaining hydrogen at a low cost without using an expensive noble metal catalyst.

As membranes for alkaline water electrolysis, asbestos cloth and ceramic porous membranes are known. However, asbestos cloth has a problem in durability at 100 ° C. or more, and there is also a problem of health damage. The ceramic porous membrane has a problem that it requires a very high-temperature treatment process at the time of processing, and also has a problem that the thickness is high and the resistance becomes high. In addition, an ion-permeable diaphragm containing a hydrophilic inorganic material has been proposed as a diaphragm used in the alkaline water electrolysis method (Patent Document 1). This ion-permeable diaphragm shows wettability to water based on the wettability of a large amount of hydrophilic inorganic material added, and has ion permeability because it is porous. Since it is essentially hydrophobic, there is a problem that the wettability with respect to alkaline water is insufficient, and in electrolysis using alkaline water as an electrolytic solution, there is a problem that electrical resistance characteristics and electrolytic performance are insufficient. Moreover, the voltage rise by the gas produced | generated by the electrode at the time of electrolysis adheres to the diaphragm surface becomes a problem.

JP 2008-144262 A

The present invention has been made in order to solve the above-described conventional problems. The object of the present invention is to provide characteristics (i.e., (1) ions required for ion-permeable membranes generally used for alkaline water electrolysis). (2) Mechanical strength and chemical stability against alkaline water, (3) No gas passage through the diaphragm, and (4) Short circuit prevention between electrodes It is an object to provide an ion-permeable diaphragm that is excellent in that the gas generated by the electrode during electrolysis adheres to the surface of the diaphragm (particularly the outermost surface).

The ion-permeable diaphragm of the present invention includes a microporous membrane, and at least one metal oxide selected from titanium oxide and zirconium oxide is attached to the microporous membrane.
In a preferred embodiment, the ion permeable membrane of the present invention further comprises a porous reinforcement.
In a preferred embodiment, at least one metal oxide selected from titanium oxide and zirconium oxide is attached to the porous reinforcing body.
In a preferred embodiment, the microporous membrane is composed of polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, ultrahigh molecular weight polyethylene, high density polyethylene, polypropylene, poly-4-methylpentene-1, polysulfone, or polyethersulfone. Has been.
In a preferred embodiment, the porous reinforcing body is composed of polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyethylene, ultrahigh molecular weight polyethylene, poly-4-methylpentene-1, polysulfone, polyethersulfone, or polyphenylene sulfide. Has been.
According to another situation of this invention, the manufacturing method of the said ion permeable diaphragm is provided. In this production method, the microporous membrane or the laminate of the microporous membrane and the porous reinforcing body is immersed in a solution containing a metal fluoride complex and a fluorine ion scavenger, and the microporous membrane or the laminate is laminated. It includes immersing in alkaline water after depositing a metal oxide on the body.
In a preferred embodiment, a heat treatment is performed after depositing a metal oxide on the microporous film or laminate.

According to the present invention, by providing a microporous film to which at least one metal oxide selected from titanium oxide and zirconium oxide is attached, excellent wettability with respect to alkaline water is exhibited. The ion permeability is excellent in ion permeability (that can contribute to lowering the electrolysis voltage), and can prevent the gas generated during electrolysis from adhering to the outermost surface of the diaphragm and suppress the increase in electrolysis voltage. A diaphragm can be obtained. The ion-permeable membrane of the present invention is excellent in durability over time even in high-concentration alkaline water, and can suppress an increase in electrical resistance (an increase in electrolysis voltage) without losing wettability with respect to alkaline water. . Further, since the ion-permeable diaphragm of the present invention is excellent in durability, it is a salt electrolysis battery, a battery using a strong alkaline to strongly acidic aqueous electrolyte, an organic solvent battery such as a lithium battery, an alkaline fuel cell, etc. It is also useful as a diaphragm for electrochemical cells.

(A) is a schematic sectional drawing of the ion permeable diaphragm by preferable embodiment of this invention. (B) is a schematic sectional view of an ion permeable membrane according to another preferred embodiment of the present invention. (C) is a schematic sectional view of an ion permeable membrane according to still another preferred embodiment of the present invention. 1 is a schematic cross-sectional view of an ion permeable diaphragm according to a preferred embodiment of the present invention.

Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment.
A. FIG. 1A is a schematic cross-sectional view of an ion permeable diaphragm according to a preferred embodiment of the present invention. An ion permeable diaphragm 100 shown in FIG. 1A includes a microporous membrane 10. At least one metal oxide 20 selected from titanium oxide and zirconium oxide is attached to the microporous film 10. FIG. 1 (b) is a schematic cross-sectional view of an ion-permeable diaphragm according to another preferred embodiment of the present invention. An ion permeable membrane 200 shown in FIG. 1B further includes a porous reinforcing body 30 on one side of the microporous membrane 10. FIG. 1 (c) is a schematic cross-sectional view of an ion permeable membrane according to still another preferred embodiment of the present invention. An ion permeable diaphragm 300 shown in FIG. 1C further includes porous reinforcing bodies 30 on both sides of the microporous membrane 10. In the present invention, the porous reinforcing body 30 may be disposed on one side of the microporous membrane 10 as shown in FIG. 1 (b), and on both sides of the microporous membrane 10 as shown in FIG. 1 (c). It may be arranged. When the porous reinforcing body 30 is disposed on one side of the microporous membrane 10, the ion permeable diaphragm 200 of the present invention may be used with the microporous membrane 10 disposed on the anode electrode side. You may arrange | position and use. When the ion-permeable diaphragm of the present invention includes a porous reinforcing body, the metal oxide 20 is preferably attached to the microporous membrane 10 and the porous reinforcing body 30.

FIG. 2 is a schematic view of an ion permeable membrane according to another preferred embodiment of the present invention. An ion permeable diaphragm 400 shown in FIG. 2 includes

microporous membranes

10 and 10 on both sides of the porous reinforcing body 30.

The ion-permeable diaphragm of the present invention has excellent wettability with respect to alkaline water due to the adhesion of at least one metal oxide selected from titanium oxide and zirconium oxide as described above, and The wettability is not easily lost for a long time. When such an ion permeable diaphragm is used for alkaline water electrolysis, the gas generated during electrolysis can be prevented from adhering to the outermost surface of the diaphragm, so that the electrolysis voltage can be lowered and the voltage rise can be suppressed. can do. Preferably, the ion-permeable membrane of the present invention exhibits good wettability (specifically, wettability such that the aqueous solution can penetrate in the thickness direction) with respect to an aqueous solution of potassium hydroxide having a concentration of 30% by weight. In addition, wettability is not easily lost for a long time in the aqueous solution. Hereinafter, in the present specification, the fact that wettability is not easily lost for a long time is also referred to as excellent wet durability. In the present specification, “showing wet durability with respect to an aqueous potassium hydroxide solution” means that the ion-permeable diaphragm is immersed in an aqueous potassium hydroxide solution at a temperature of 80 ° C./concentration of 30% by weight for 100 hours. It also means that wettability is not lost. Specifically, when the potassium hydroxide aqueous solution having a concentration of 30% by weight is dropped on the outermost surface of the ion-permeable diaphragm after being immersed in the potassium hydroxide aqueous solution as described above, the dropped potassium hydroxide aqueous solution is When reaching the surface on the opposite side, the ion-permeable membrane is referred to as an ion-permeable membrane that “shows wet durability against an aqueous potassium hydroxide solution”.

The thickness of the ion-permeable membrane of the present invention is preferably 15 μm to 1500 μm, more preferably 35 μm to 1000 μm, still more preferably 55 μm to 600 μm, and particularly preferably 80 μm to 400 μm.

B. Microporous membrane The material constituting the microporous membrane is sufficient as an ion permeable membrane (specifically, for example, a membrane for alkaline water electrolysis) under a condition where a high potential is applied in a high-temperature strongly alkaline aqueous solution. A material having chemical stability and capable of maintaining sufficient mechanical strength is preferably used. More specifically, the diaphragm for alkaline water electrolysis under the condition that a potential of 1.5 V to 3 V is applied in a potassium hydroxide aqueous solution or sodium hydroxide having a concentration of 10 wt% to 40 wt% / temperature of 60 ° C. to 100 ° C. A material having sufficient chemical stability and capable of maintaining sufficient mechanical strength is preferably used. Examples of such a material include a fluorine polymer, an olefin polymer, and an aromatic hydrocarbon polymer.

Examples of the fluorine-based polymer include polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. And polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer, and the like. Of these, polytetrafluoroethylene and polyvinylidene fluoride are preferable. It is because it is excellent in chemical stability.

Examples of the olefin polymer include low density polyethylene, high density polyethylene, ultrahigh molecular weight polyethylene, polypropylene, polybutene, poly-4-methylpentene-1, and a copolymer having a repeating unit constituting these compounds. Etc. Among these, polypropylene, ultrahigh molecular weight polyethylene, high density polyethylene, polypropylene, and poly-4-methylpentene-1 are preferable. It is because it is excellent in chemical stability. The viscosity average molecular weight of the ultra high molecular weight polyethylene is preferably 500,000 to 10,000,000, more preferably 1,000,000 to 7,000,000. In addition, the said viscosity average molecular weight can be measured by the viscosity method prescribed | regulated to ASTMD4020.

Examples of the aromatic hydrocarbon polymer include polyether ether ketone, polyether ketone, polysulfone, polyether sulfone, polyphenylene sulfide, polyarylate, polyether imide, polyimide, thermoplastic polyimide, and compounds thereof. Examples thereof include a copolymer having a constituting repeating unit. Of these, polysulfone and polyethersulfone are preferable. It is because it is excellent in chemical stability.

The microporous membrane can be obtained by making the material porous by any appropriate method. Examples of the method for making porous include a phase conversion method (microphase separation method), an extraction method, a stretching method, a wet gel stretching method, and the like. The phase inversion method (microphase separation method) is a method of forming a film with a solution obtained by dissolving a polymer material in a good solvent and coagulating it in a poor solvent. The extraction method is a method in which an inorganic powder such as calcium carbonate is kneaded into a polymer material to form a film, and after the film formation, the inorganic powder is dissolved and extracted, and further stretched as necessary. The stretching method is a method in which a film is formed from a polymer material having a predetermined crystal structure and then stretched under predetermined conditions. The wet gel stretching method is a method in which a mixture of ultra high molecular weight polyethylene and high density polyethylene is thermally swollen with liquid paraffin to form a gel-like sheet, which is biaxially stretched, and then liquid paraffin is extracted and removed.

The microporous membrane preferably has hydrophilicity. If the microporous membrane has hydrophilicity, a necessary and sufficient metal oxide can be uniformly attached to the microporous membrane. Hydrophilization of the microporous membrane can be performed by any appropriate hydrophilic treatment, but hydrophilic treatment that can impart hydrophilic durability that does not impair the hydrophilicity in the operation of depositing metal oxide (described later). Is preferred. By performing such a hydrophilic treatment on the microporous film before adhering the metal oxide, the metal oxide precipitation reaction first occurs in the form of dots, and then the microporous film with the point as a nucleus. Spread to cover the entire surface. Further, if a microporous film having hydrophilicity is used, it is possible to prevent the attached metal oxide from falling off. As a method for hydrophilizing the microporous membrane, for example, gas phase treatment such as UV ozone treatment, corona treatment, sputter etching treatment, plasma treatment; potassium dichromate / concentrated sulfuric acid treatment, metallic sodium / naphthalene / tetrahydrofuran treatment, hydrophilicity And chemical treatments such as graft polymerization treatment of hydrophilic monomers, crosslinking or coating treatment of hydrophilic polymers, and the like. Of these, potassium dichromate / concentrated sulfuric acid treatment, metallic sodium / naphthalene / tetrahydrofuran treatment, hydrophilic monomer graft polymerization treatment, hydrophilic polymer Chemical treatment such as crosslinking or coating treatment. Moreover, if such a process is performed, the microporous film excellent in hydrophilic durability can be obtained.

Any appropriate method can be adopted as the graft polymerization treatment method. Examples of the hydrophilic monomer used in the graft polymerization treatment include acrylic acid, methacrylic acid, 2-hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2 -Hydroxymethyl methacrylate, 2-hydroxyethyl methacrylate, vinyl acetate, allylamine, acrylamide, methacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N, N-dimethylaminopropylacrylamide, N, N-dimethylamino Ethyl acrylate 2- (dimethylamino) ethyl acrylate, N- (2-hydroxyethyl) acrylamide, acryloylmorpholine, N-isopropyla Rilamide, acrylonitrile, methacrylonitrile, 1-vinylimidazole, 2-vinylpyridine, 4-vinylpyridine, methylvinylpyridine, ethylvinylpyridine, vinylpyrrolidone, vinylcarbazole, aminostyrene, alkylaminostyrene, dialkylaminostyrene, trialkyl Examples include aminostyrene, vinylbenzyltrimethylammonium chloride, styrenesulfonic acid, sodium styrenesulfonate, potassium styrenesulfonate, lithium styrenesulfonate, vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and the like. Of these, acrylic acid, methacrylic acid, 2-hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxymethyl methacrylate, 2-hydroxyethyl methacrylate, acrylamide or methacrylamide are preferable. These monomers may be used alone or in combination of two or more.

Examples of the hydrophilic polymer used for the crosslinking or coating treatment of the hydrophilic polymer include polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyvinyl acetate, polyacrylamide, polymethacrylamide, poly (N, N-dimethylacrylamide), Examples include polyvinyl pyrrolidone, styrene sulfonic acid, vinyl sulfonic acid, and polyethylene glycol. The coating of the hydrophilic polymer can be performed, for example, by immersing a microporous membrane wetted with alcohol in an aqueous hydrophilic polymer solution.

The thickness of the microporous membrane is preferably 10 μm to 200 μm, more preferably 20 μm to 150 μm. Within such a range, when used as a diaphragm for electrolysis, it is possible to obtain an ion permeable diaphragm having excellent product gas separation performance and excellent ion permeability.

The pore diameter of the microporous membrane is preferably 0.001 μm to 10 μm, more preferably 0.01 μm to 2 μm, and still more preferably 0.02 μm to 1.0 μm. Within such a range, when used as a diaphragm for electrolysis, it is possible to obtain an ion permeable diaphragm having excellent product gas separation performance and excellent ion permeability.

The porosity of the microporous membrane is preferably 10% to 90%, more preferably 30% to 85%, and further preferably 50% to 85%. When the porosity is lower than 10%, the ion permeation resistance may be increased. When the porosity is higher than 90%, the strength of the membrane is insufficient, the membrane may be crushed, and the ion permeation resistance may be increased. A higher porosity within the range allowed by the film strength is preferable because the ion permeation resistance can be lowered. In the present specification, the porosity of the microporous membrane refers to a value calculated by the formula {1- (apparent density of microporous membrane / true specific gravity of the material constituting the microporous membrane)} × 100. .

C. Metal oxide At least one metal oxide selected from titanium oxide and zirconium oxide is attached to the microporous film. More specifically, the metal oxide is attached to the surface of the microporous film. Here, the surface of the microporous membrane refers to the interface (pore surface) between the material constituting the microporous membrane and air when no metal oxide is attached. That is, the metal oxide can exist not only near the outside of the microporous membrane (near the outer surface) but also inside the microporous membrane. The metal oxide may be attached so as to cover the entire surface of the microporous film, or may be attached so as to cover a part of the surface. For example, as described in the above section B, the metal oxide can be adhered over a wide range by previously hydrophilizing the microporous membrane. The metal oxide is preferably attached so as to form a coating on at least a part of the surface of the microporous membrane, and more preferably attached so as to form a coating on the entire surface of the microporous membrane.

The adhesion rate of the metal oxide is preferably 10% to 200%, more preferably 15% to 100%, still more preferably 20% to 100%, and particularly preferably 20% to 70%. is there. If the adhesion rate is less than 10%, the wettability with respect to alkaline water and the wet durability may be insufficient. When the adhesion rate is higher than 200%, the metal oxide may block the pores of the microporous membrane and the ion permeability may be reduced. In the present specification, the adhesion rate is the weight of the metal oxide relative to the weight of the microporous membrane (the total weight of the microporous membrane and the porous reinforcing body in the case of having a porous reinforcing body as described later). Specifically, (the total weight of the microporous membrane and the porous reinforcing body after adhesion of the metal oxide-the total weight of the microporous membrane and the porous reinforcing body before the deposition of the metal oxide) / (metal oxidation) It is a value calculated by the formula of the total weight of the microporous membrane and the porous reinforcing body before adhesion of an object).

Examples of the method for attaching the metal oxide to the microporous film include a liquid phase precipitation method described in JP-A-2008-44826. The liquid phase precipitation method is a method utilizing a hydrolysis equilibrium reaction of a metal fluoride complex. For example, in the hydrolysis reaction of a metal fluoride complex as shown in the following reaction formula (1), F ⁻ Fluorine ion scavenger (for example, H ₃ BO ₃ as shown in the following reaction formula (2)) that adds ions as a ligand and forms a fluoride complex or compound that is more stable than the metal fluoride complex is added. In this way, the equilibrium reaction of the chemical formula (1) is moved to the oxide production side, and a method of depositing a metal oxide is used. More specifically, the metal oxide can be deposited on the microporous film by immersing the microporous film in a solution containing the metal fluoride complex and the fluorine ion scavenger.

The metal fluoride complexes, for _{_{_{_{example, (NH 4) 2 TiF 6}}}} , include _(NH 4) 2 ZrF ₆ and the like.

As the fluorine ion scavenger, a compound capable of forming a stable complex with fluorine ions can be used. Examples of the fluorine ion scavenger include H ₃ BO ₃ , sodium hydroxide, potassium hydroxide, aluminum chloride, aluminum hydroxide, and metal aluminum.

The concentration of the metal fluoride complex in the solution containing the metal fluoride complex and the fluorine ion scavenger is preferably 0.01 mol / L to 2 mol / L, more preferably 0.05 mol / L to 0.5 mol. / L. If the concentration of the metal fluoride complex is too low, the amount of metal oxide attached may be insufficient. On the other hand, if the concentration is too high, it may be difficult to dissolve the metal oxide, and / or metal There is a possibility that oxides are generated excessively and clog the pores of the microporous membrane.

The concentration of the fluorine ion scavenger in the solution containing the metal fluoride complex and the fluorine ion scavenger is preferably 0.05 mol / L to 2 mol / L, more preferably 0.1 mol / L to 0.5 mol. / L. If the concentration of the fluorine ion scavenger is too low, the amount of metal oxide attached may be insufficient. On the other hand, when the concentration is too high, the deposition reaction rate of the metal oxide is increased, and there is a possibility that the precipitation in the solution is larger than the precipitation in the microporous film.

Any appropriate solvent can be used as the solvent of the solution containing the metal fluoride complex and the fluorine ion scavenger as long as the solvent can dissolve the metal fluoride complex and the fluorine ion scavenger. Specific examples of the solvent include water, acetonitrile and the like.

The temperature (reaction temperature) and the immersion time (reaction time) when the microporous membrane is immersed in a solution containing the metal fluoride complex and the fluorine ion scavenger can be set to any appropriate condition. Typically, the reaction temperature is preferably 25 ° C to 100 ° C. The immersion time (reaction time) is preferably 10 minutes to 48 hours. In this way, it is possible to obtain an ion-permeable diaphragm in which a metal oxide is attached to the microporous film.

After the metal oxide is adhered to the surface of the microporous film as described above, heat treatment may be further performed in a gas phase such as an inert gas. Examples of the inert gas include air, nitrogen, and the like. The heat treatment can be performed when the composition and / or crystal structure of the metal oxide is incomplete. When heat treatment is performed, the reaction represented by the above reaction formula (1) is promoted, and a metal oxide having a desired composition and / or crystal structure can be obtained. As a result, it is possible to obtain an ion-permeable diaphragm that is excellent in durability under an actual use environment. The temperature of the heat treatment is, for example, 100 ° C. to 400 ° C. The heat treatment time is, for example, 1 minute to 24 hours. The heating temperature is preferably set in a range that does not adversely affect the structure of the microporous membrane. Moreover, if it is such a range, the time of heat processing can be shortened, so that temperature is high.

In one embodiment, after depositing a metal oxide on the microporous film as described above (after heat treatment when heat treatment is performed), the microporous film is immersed in alkaline water. As the alkaline water, for example, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution having a concentration of 10 to 40% by weight can be used. The temperature of the alkaline water is preferably 60 ° C. to 120 ° C., more preferably 70 ° C. to 90 ° C. The immersion time is preferably 1 hour to 200 hours, more preferably 2 hours to 100 hours. Thus, by immersing in alkaline water, an ion-permeable diaphragm that is remarkably excellent in wettability and wettability with respect to alkaline water (for example, potassium hydroxide aqueous solution) can be obtained. The mechanism by which such an ion permeable membrane is obtained is not clear, but by soaking in alkaline water, the hydrophilic functional groups of the polymer or metal oxide constituting the microporous membrane are increased, resulting in wettability and wettability. It is thought that durability is improved.

D. Porous reinforcement As described above, the ion-permeable diaphragm of the present invention may include a porous reinforcement. By reinforcing the microporous membrane with the porous reinforcing body, the strength as the diaphragm for electrolysis can be improved, and the short-circuit preventing property between the electrodes can be improved. Specifically, in alkaline water electrolysis, when the gap between the diaphragm and the electrode is substantially eliminated in order to reduce the applied voltage, the diaphragm is generally easily damaged and short-circuited by the unevenness of the electrode. By providing the porous reinforcing body as described above, an ion-permeable diaphragm that is less likely to be damaged or short-circuited can be obtained. In addition, since the porous reinforcing body is porous, the above effects can be exhibited without impairing ion permeability. Furthermore, the strength is improved by providing the porous reinforcing body, and an ion-permeable diaphragm having sufficient strength can be obtained even if the thickness is reduced.

The microporous membrane and the porous reinforcing body are preferably integrated by, for example, thermal lamination. By integrating, the workability at the time of assembling the electrolytic cell can be improved, and gas can be prevented from accumulating between the microporous membrane and the porous reinforcing body, thereby preventing an increase in electrolytic resistance. Thermal lamination is performed by applying a predetermined pressure to a material constituting the microporous membrane and the porous reinforcing body at a temperature equal to or higher than the melting point of at least one of the materials by a pair of heating rolls, a hot press, or the like. be able to. Further, the microporous membrane and the porous reinforcing body may be integrated through an adhesive layer. Any appropriate adhesive can be used as the adhesive constituting the adhesive layer as long as the effects of the present invention can be obtained. Examples of the adhesive layer include an adhesive layer obtained by applying a polyolefin-based hot melt material in a mesh shape.

As the material constituting the porous reinforcing body, a polymer having excellent strength and having mechanical durability and chemical durability against alkaline water is preferably used. Examples of the material constituting the porous reinforcing body include polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyethylene, ultrahigh molecular weight polyethylene, poly-4-methylpentene-1, polysulfone, polyethersulfone, and polyphenylene sulfide. It is done.

The porous reinforcing body is porous. Examples of the form of the porous reinforcing body include a woven fabric, a nonwoven fabric, a net, a mesh, and a sintered porous membrane. A nonwoven fabric, a mesh or a sintered porous membrane is preferred, and a sintered porous membrane is more preferred. A sintered porous membrane is excellent in strength and ion permeability. Examples of a method for obtaining a sintered porous film include a sintering method described in JP-A-2-214647.

The thickness of the porous reinforcing body is preferably 30 μm to 800 μm, more preferably 50 μm to 500 μm. If it is a porous reinforcement body which has the thickness of such a range, it has sufficient intensity | strength as a reinforcement body, sufficient ion permeability, and can prevent the short circuit of an electrode.

When the form of the porous reinforcing body is a sintered porous membrane, the porosity of the porous reinforcing body is preferably 10% to 80%, more preferably 20% to 60%. When the porosity is lower than 10%, the ion permeation resistance may be increased. If the porosity is higher than 80%, the strength may be insufficient.

The porous reinforcing body preferably has hydrophilicity. If the porous reinforcing body has hydrophilicity, a necessary and sufficient metal oxide can be uniformly attached to the porous reinforcing body. Hydrophilization of the porous reinforcing body can be performed, for example, by the method described in the above section B. When the ion-permeable membrane of the present invention includes a porous reinforcement, the hydrophilic treatment of the porous reinforcement may be performed separately from the hydrophilic treatment of the microporous membrane. The microporous membrane and the porous reinforcement Hydrophilic treatment may be performed on the laminate.

Preferably, at least one metal oxide selected from titanium oxide and zirconium oxide is attached to the porous reinforcing body. More specifically, the metal oxide is attached to the surfaces of the microporous membrane and the porous reinforcing body. The surface of the microporous membrane is as described in the above section C. The surface of the porous reinforcing body refers to the interface between the material constituting the porous reinforcing body and air when no metal oxide is attached. That is, the metal oxide can be present not only near the outside (near the outer surface) of the microporous membrane and / or porous reinforcing body but also inside the microporous membrane and / or porous reinforcing body. The metal oxide may be attached so as to cover the entire surface of the porous reinforcing body, or may be attached so as to cover a part of the surface. For example, the metal oxide can be adhered over a wide range by hydrophilizing the porous reinforcing body in advance. The metal oxide is preferably attached so as to form a film on at least a part of the surface of the porous reinforcing body, and more preferably attached so as to form a film on the entire surface of the porous reinforcing body. . Examples of the method for attaching the metal oxide to the porous reinforcing body include the method described in the above section C. It is preferable that a microporous membrane and a porous reinforcing body are laminated, and a metal oxide is attached to the obtained laminated body by the liquid phase precipitation method described in the above section C.

After the metal oxide is attached to the porous reinforcing body, the heat treatment as described in the above section C may be performed. In one embodiment, a microporous membrane and a porous reinforcing body are laminated, and a heat treatment is performed on the obtained laminated body.

In one embodiment, after depositing a metal oxide on the microporous membrane and the porous reinforcing body (after heat treatment when heat treatment is performed), a laminate of the microporous membrane and the porous reinforcing body is formed. Immerse in alkaline water. As the alkaline water, for example, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution having a concentration of 10 to 40% by weight can be used. The temperature of the alkaline water is preferably 60 ° C. to 120 ° C., more preferably 70 ° C. to 90 ° C. The immersion time is preferably 1 hour to 200 hours, more preferably 2 hours to 100 hours. Thus, by immersing in alkaline water, an ion-permeable diaphragm that is remarkably excellent in wettability and wettability with respect to alkaline water (for example, potassium hydroxide aqueous solution) can be obtained.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The evaluation methods in the examples are as follows. In Examples, unless otherwise specified, “parts” and “%” are based on weight.

(1) Measurement of thickness Digital upright gauge R1-205 (manufactured by Ozaki Seisakusho; measuring element: Φ5 mm, measuring force: 1.1 N or less) was used for the thickness. Unless otherwise specified, the values are measured at 25 ± 2 ° C. and 65 ± 20% RH.
(2) Metal oxide adhesion rate The metal oxide adhesion rate was calculated by the following equation.
Adhesion rate (%) = (total weight of microporous membrane and porous reinforcing body after metal oxide deposition−total weight of microporous membrane and porous reinforcing body before metal oxide deposition) / (before metal oxide deposition) Total weight of microporous membrane and porous reinforcing body)
(3) Wettability with respect to aqueous potassium hydroxide solution An ion-permeable membrane was immersed in an aqueous 30 wt% potassium hydroxide solution maintained at 80 ° C. for 100 hours. Thereafter, the porous reinforcing body was pulled up, and the remaining potassium hydroxide aqueous solution was sufficiently washed and removed, and then dried. Next, a pH test paper (manufactured by ASONE, product number “1-1745-01”) is applied to one surface (back surface) of the porous reinforcing body, and hydroxylation at a concentration of 30% by weight from the other surface (front surface). One drop (about 50 mg) of an aqueous potassium solution was added dropwise. After 10 minutes from dropping, when the potassium hydroxide aqueous solution reached the back surface and the pH test paper was discolored, it was judged that there was wettability.
(4) Alkaline water electrolysis evaluation Alkaline water electrolysis evaluation of the ion-permeable diaphragms obtained in Examples and Comparative Examples was performed using an H-cell made of acrylic resin. The electrolyte used was an aqueous solution of potassium hydroxide having a concentration of 30% by weight, and the electrode used was an electrode (effective electrode diameter of Φ30 mm, aperture ratio of 40%) having 90 holes of Φ2 mm in a 1 mm thick Ni plate. . The liquid temperature at the time of measurement was set to 25 ° C. The current density was 0.2 A / cm ² , the voltage when a constant current was applied continuously for 1 hour was measured, and alkaline water electrolysis was evaluated based on the average value of the measured values 55 minutes to 1 hour after the start of measurement. Went. The measurement was performed after the ion-permeable diaphragm was immersed in the electrolyte for 10 minutes. In the case where the ion-permeable diaphragm has a two-layer structure (Examples 1 to 9 and Comparative Example 6), the measurement was performed with the microporous membrane placed on the anode side.

[Example 1]
A polytetrafluoroethylene (PTFE) porous membrane (trade name “TEMISH NTF-1122” manufactured by Nitto Denko Corporation, pore size 0.2 μm, thickness 85 μm) is dipped in 2-propanol and wetted, and then the membrane is not dried. And then immersed in an aqueous solution of polyvinyl alcohol (PVA, degree of polymerization 2000) (concentration: 1.2% by weight) and allowed to stand at 25 ° C. for 30 minutes for replacement. Thereafter, this porous PTFE membrane was immersed in a crosslinking liquid (liquid temperature: 35 ° C.) prepared by mixing 90 g of a glutaraldehyde aqueous solution (concentration 25 wt%), 15 g of 6 molar hydrochloric acid and 795 g of pure water for 1 hour. And a crosslinking reaction was carried out. Next, after removing the PTFE porous membrane from the cross-linking liquid, washing with pure water 5 times, the PTFE porous membrane is fixed to the stainless steel frame with a clip in a wet state, and a hot air circulating dryer at 80 ° C. And dried for 30 minutes to obtain a hydrophilic microporous membrane. In the above formula for calculating the adhesion rate of the metal oxide, the “total weight of the microporous membrane and the porous reinforcing body before the metal oxide adhesion” refers to the weight of the microporous membrane subjected to the hydrophilic treatment.
Separately, 17.4 g of ammonium hexafluorotitanate (manufactured by Wako Pure Chemical Industries) was dissolved in 440 g of pure water, and 5.4 g of boric acid (manufactured by Wako Pure Chemical Industries) was dissolved in 176 g of pure water. The obtained solution was mixed to prepare a solution for titanium oxide precipitation. The hydrophilic microporous membrane (80 × 120 mm) is immersed in 100 g of this solution, heated at 60 ° C. for 9 hours, and further at 80 ° C. for 3 hours, and TiO ₂ is added to the microporous membrane. Precipitated. Thereafter, the microporous membrane is taken out from the solution, fixed with a clip to a stainless steel frame in a wet state, and heat-treated for 30 minutes with a hot air circulating dryer at 80 ° C. to obtain an ion-permeable membrane (thickness: 84 μm). ) In the equation for calculating the adhesion rate of the metal oxide, “the total weight of the microporous membrane and the porous reinforcing body after the metal oxide is deposited” refers to the weight of the ion-permeable diaphragm.
The obtained ion-permeable diaphragm was subjected to the above evaluations (1) to (4). The results are shown in Table 1.

[Example 2]
Polytetrafluoroethylene (PTFE) porous membrane (trade name “Temisch NTF-1131” manufactured by Nitto Denko Corporation, pore size 1.0 μm, thickness 85 μm) as a microporous membrane, and spun pond non-woven fabric (Unitika) as a porous reinforcement Product name “T0303 / WD0”, core: polyester / sheath: polyethylene, weight per unit area 30 g / m ² , thickness 170 μm) are thermally bonded with a heating roll at 135 ° C. to obtain a laminate (microporous membrane / porous) Strength reinforcement).
This laminate was dipped in 2-propanol and wetted, and then dipped in an aqueous solution of polyvinyl alcohol (PVA, polymerization degree 2000) (concentration: 1.2% by weight) so that the laminate was not dried, at 25 ° C. Replaced by standing for 30 minutes. Thereafter, this laminate was immersed in a crosslinking liquid (liquid temperature: 35 ° C.) prepared by mixing 90 g of a glutaraldehyde aqueous solution (concentration 25% by weight), 15 g of 6 molar hydrochloric acid and 795 g of pure water, and crosslinked for 1 hour. Reacted. Next, the laminate is taken out of the cross-linking solution, washed 5 times with pure water, then fixed with a clip on a stainless steel frame in a wet state, and dried for 30 minutes with a hot air circulating dryer at 80 ° C. Thus, a laminate subjected to hydrophilic treatment was obtained. In the formula for calculating the adhesion rate of the metal oxide, “the total weight of the microporous membrane and the porous reinforcing body before the metal oxide is adhered” refers to the weight of the hydrophilically treated laminate.
Separately, 17.4 g of ammonium hexafluorotitanate (manufactured by Wako Pure Chemical Industries) was dissolved in 440 g of pure water, and 5.4 g of boric acid (manufactured by Wako Pure Chemical Industries) was dissolved in 176 g of pure water. The obtained solution was mixed to prepare a solution for titanium oxide precipitation. The hydrophilically treated laminate (80 × 120 mm) is immersed in 100 g of this solution and heated at 60 ° C. for 9 hours and further at 80 ° C. for 3 hours to obtain a laminate (that is, a microporous membrane). TiO ₂ was deposited on the porous reinforcing body). Thereafter, the laminate is taken out of the solution, fixed in a stainless steel frame with a clip in a wet state, and heat-treated for 30 minutes with a hot air circulating dryer at 80 ° C. to obtain an ion-permeable diaphragm (thickness: 146 μm). Got. In the equation for calculating the adhesion rate of the metal oxide, “the total weight of the microporous membrane and the porous reinforcing body after the metal oxide is deposited” refers to the weight of the ion-permeable diaphragm.
The obtained ion-permeable diaphragm was subjected to the above evaluations (1) to (4). The results are shown in Table 1.

[Example 3]
Polytetrafluoroethylene (PTFE) porous membrane (manufactured by Nitto Denko Corporation, trade name “Temish NTF-1131”, pore diameter 1.0 μm, thickness 85 μm), polytetrafluoroethylene (PTFE) porous membrane (Nitto Denko Corporation) An ion-permeable membrane (thickness: 120 μm) was obtained in the same manner as in Example 2 except that the product name “Temisch NTF-1026”, pore diameter 0.6 μm, thickness 25 μm) was used.
The obtained ion-permeable diaphragm was subjected to the above evaluations (1) to (4). The results are shown in Table 1.

[Example 4]
As the microporous membrane, a hydrophilic polyvinylidene fluoride (PVdF) porous membrane (trade name “Durapore membrane filter GVWP14250”, pore size 0.22 μm, manufactured by Millipore) was used. In the formula for calculating the adhesion rate of the metal oxide, the “total weight of the microporous membrane and the porous reinforcing body before the metal oxide adhesion” refers to the hydrophilic polyvinylidene fluoride (PVdF) porous membrane. Refers to weight.
Separately, 17.4 g of ammonium hexafluorotitanate (manufactured by Wako Pure Chemical Industries) was dissolved in 440 g of pure water, and 5.4 g of boric acid (manufactured by Wako Pure Chemical Industries) was dissolved in 176 g of pure water. The obtained solution was mixed to prepare a solution for titanium oxide precipitation. The hydrophilized polyvinylidene fluoride porous membrane (80 × 120 mm) is immersed in 100 g of this solution, heated at 60 ° C. for 9 hours, and further at 80 ° C. for 3 hours to form TiO _{2 on the} microporous membrane. Was precipitated. Thereafter, the microporous membrane is taken out from the solution, fixed in a wet state with a clip to a stainless steel frame, and heat-treated for 30 minutes with a hot air circulating dryer at 80 ° C. to obtain an ion-permeable membrane (thickness: 123 μm). ) In the equation for calculating the adhesion rate of the metal oxide, “the total weight of the microporous membrane and the porous reinforcing body after the metal oxide is deposited” refers to the weight of the ion-permeable diaphragm.
The obtained ion-permeable diaphragm was subjected to the above evaluations (1) to (4). The results are shown in Table 1.

[Example 5]
Hydrophilic polyvinylidene fluoride (PVdF) porous membrane (Millipore's product name “Durapore membrane filter GVWP14250”, pore size 0.22 μm), instead of hydrophilic polyvinylidene fluoride (PVdF) porous membrane (Millipore product) An ion permeable membrane (thickness: 111 μm) was obtained in the same manner as in Example 4 except that the name “Durapore membrane filter HVLP14250” (pore diameter 0.45 μm) was used.
The obtained ion-permeable diaphragm was subjected to the above evaluations (1) to (4). The results are shown in Table 1.

[Example 6]
Polytetrafluoroethylene (PTFE) porous membrane (trade name “Temisch NTF-1122” manufactured by Nitto Denko Corporation, pore diameter 0.2 μm, thickness 80 μm) as a microporous membrane and non-woven fabric (Hirose Paper Co., Ltd.) as a porous reinforcement Product name “HOP-60HCF”, core: polypropylene / sheath: polyethylene, basis weight 60 g / m ² , thickness 160 μm) and heat bonded with a heating roll at 145 ° C. to laminate (microporous membrane / porous) Reinforcing body) was obtained.
Except that the temperature of the heat treatment after depositing TiO ₂ on the laminate (that is, the microporous membrane and the porous reinforcing body) was 100 ° C. using the laminate, A permeable membrane (thickness: 218 μm) was obtained.

[Example 7]
Polytetrafluoroethylene (PTFE) porous membrane (trade name “Temisch NTF-1122” manufactured by Nitto Denko Corporation, pore diameter 0.2 μm, thickness 80 μm) as a microporous membrane and non-woven fabric (Hirose Paper Co., Ltd.) as a porous reinforcement Product name “HOP-60HCF”, core: polypropylene / sheath: polyethylene, basis weight 60 g / m ² , thickness 160 μm) and heat bonded with a heating roll at 145 ° C. to laminate (microporous membrane / porous) Reinforcing body) was obtained.
Further, the laminate was subjected to a hydrophilic treatment in the same manner as in Example 2 to obtain a hydrophilic treated laminate.
Separately, a solution obtained by dissolving 7.77 g of zircon hydrofluoric acid (Morita Chemical Co., Ltd.) in 67.2 g of pure water;
A solution obtained by dissolving 0.62 g of boric acid (manufactured by Wako Pure Chemical Industries, Ltd.) in 19.4 g of pure water was mixed to prepare a solution for precipitation of zirconium oxide. An aluminum plate (A1050, thickness 0.2 mm × 100 mm × 100 mm) and the hydrophilically treated laminate (80 × 120 mm) are immersed in 95.0 g of this solution, and left at 25 ° C. for 150 hours. Then, ZrO ₂ was deposited on the laminate (that is, the microporous film and the porous reinforcing body). Thereafter, the laminate is taken out of the solution, fixed with a clip to a stainless steel frame in a wet state, and heat-treated for 30 minutes with a hot air circulation dryer at 80 ° C. to obtain an ion-permeable diaphragm (thickness: 240 μm). Got. In the equation for calculating the adhesion rate of the metal oxide, “the total weight of the microporous membrane and the porous reinforcing body after the metal oxide is deposited” refers to the weight of the ion-permeable diaphragm.
The obtained ion-permeable diaphragm was subjected to the above evaluations (1) to (4). The results are shown in Table 1.

[Example 8]
In the same manner as in Example 1, a microporous membrane subjected to hydrophilic treatment was obtained.
Separately, a solution obtained by dissolving 7.77 g of zircon hydrofluoric acid (Morita Chemical Co., Ltd.) in 67.2 g of pure water;
A solution obtained by dissolving 0.62 g of boric acid (manufactured by Wako Pure Chemical Industries, Ltd.) in 19.4 g of pure water was mixed to prepare a solution for precipitation of zirconium oxide. An aluminum plate (A1050, thickness 0.2 mm × 100 mm × 100 mm) and the above-mentioned hydrophilic microporous film (80 × 120 mm) were immersed in 95.0 g of this solution, and the plate was allowed to stand at 25 ° C. for 150 hours. And ZrO ₂ was deposited on the microporous membrane. Thereafter, the microporous membrane is taken out from the solution, fixed in a stainless steel frame with a clip in a wet state, and heat-treated for 30 minutes with a hot air circulating dryer at 150 ° C. to obtain an ion-permeable membrane (thickness: 73 μm). ) In the equation for calculating the adhesion rate of the metal oxide, “the total weight of the microporous membrane and the porous reinforcing body after the metal oxide is deposited” refers to the weight of the ion-permeable diaphragm.
The obtained ion-permeable diaphragm was subjected to the above evaluations (1) to (4). The results are shown in Table 1.

[Example 9]
An ion permeable membrane (thickness: 85 μm) was obtained in the same manner as in Example 1 except that the temperature of the heat treatment after depositing TiO ₂ on the microporous membrane was 200 ° C.
The obtained ion-permeable diaphragm was subjected to the above evaluations (1) to (4). The results are shown in Table 1.

[Example 10]
Polytetrafluoroethylene (PTFE) porous membrane (trade name “Temisch NTF-1122” manufactured by Nitto Denko Corporation, pore diameter 0.2 μm, thickness 80 μm) as a microporous membrane and non-woven fabric (Hirose Paper Co., Ltd.) as a porous reinforcement Product name “HOP-60HCF”, core: polypropylene / sheath: polyethylene, weight per unit area 60 g / m ² , thickness 160 μm) are thermally bonded with a heating roll at 145 ° C. to form a laminate (microporous) Membrane / porous reinforcing body / microporous membrane, thickness 260 μm).
An ion-permeable diaphragm (thickness: 265 μm) was obtained in the same manner as in Example 2 except that this laminate was used.
The obtained ion-permeable diaphragm was subjected to the above evaluations (1) to (4). The results are shown in Table 1.

[Comparative Example 1]
First, 30 g of 1-methyl-2-pyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.) and 12 g of calcium fluoride (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed and sufficiently stirred with a homomixer. 4 g of polysulfone (trade name “ULTRASON S6010” manufactured by BASF) was added thereto, heated to 60 ° C., sufficiently stirred and dissolved again, and then defoamed to prepare a suspension.
A 200-mesh, 190-μm thick polyethylene net (nip (polyethylene) strong net, manufactured by NBC Co., Ltd.) was stretched and 10 ml of the suspension was poured onto a 10 cm × 10 cm glass frame placed on the bottom. . Thereafter, the frame into which the suspension was poured was immersed in pure water at 25 ° C. and left at room temperature for 10 minutes to extract 1-methyl-2-pyrrolidone. Thereafter, the solidified sheet-like material is peeled off from the frame, further washed in pure water at 25 ° C. for 30 minutes, air-dried at 25 ° C., and then dried in a dryer at 80 ° C. for 30 minutes, to form a sheet-like ion permeability A diaphragm (thickness: 841 μm) was obtained.
The obtained ion-permeable diaphragm was used for the evaluations (1) and (3). The results are shown in Table 1. The ion permeable membrane obtained in Comparative Example 1 has many irregularities on the surface, the film thickness varies from 570 μm to 1170 μm, and electrolyte leakage due to poor sealing is generated, so alkaline water electrolysis evaluation is not possible. There wasn't.

[Comparative Example 2]
First, 30 g of 1-methyl-2-pyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.) and 24 g of calcium fluoride (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed and sufficiently stirred with a homomixer. 8 g of polysulfone (trade name “ULTRASON S6010” manufactured by BASF) was added thereto, heated to 60 ° C., sufficiently stirred and dissolved again, and then defoamed to prepare a suspension.
Next, the suspension was applied to a glass plate with a gap of 300 μm using a Baker type applicator. A 200 mesh, 190 μm thick polyethylene net (nip (polyethylene) strong net, manufactured by NBC)) was placed on this, and surface pressure was applied by a hand roller to sufficiently soak the suspension in the mesh. Thereafter, the suspension was applied again at a gap of 400 μm using a Baker type applicator in the same manner. Thereafter, the glass plate was immersed in pure water at 25 ° C. and left at room temperature for 10 minutes to extract 1-methyl-2-pyrrolidone. The solidified sheet is peeled off, further washed in pure water at 25 ° C. for 30 minutes, air-dried at 25 ° C., and then dried in an oven at 80 ° C. for 30 minutes to obtain a sheet-like ion-permeable membrane (thickness). : 343 μm). The obtained ion permeable diaphragm had a smooth surface and a uniform film thickness of around 340 μm.
The obtained ion-permeable diaphragm was used for the evaluations (1), (3) and (4). The results are shown in Table 1.

[Comparative Example 3]
The hydrophilic microporous membrane obtained in Example 1, that is, a microporous membrane (thickness: 77 μm) to which no metal oxide was adhered was subjected to the above evaluations (1) to (4). The results are shown in Table 1.

[Comparative Example 4]
A hydrophilic polyvinylidene fluoride (PVdF) porous membrane (trade name “Durapore membrane filter GVWP14250” manufactured by Millipore, pore diameter 0.22 μm, thickness: 116 μm) was subjected to the above evaluations (1) to (4). The results are shown in Table 1.

[Comparative Example 5]
A hydrophilic polyvinylidene fluoride (PVdF) porous membrane (trade name “Durapore membrane filter HVLP14250” manufactured by Millipore, pore diameter 0.45 μm, thickness: 104 μm) was subjected to the above evaluations (1) to (4). The results are shown in Table 1.

[Comparative Example 6]
Polytetrafluoroethylene (PTFE) porous membrane (trade name “Temisch NTF-1122” manufactured by Nitto Denko Corporation, pore diameter 0.2 μm, thickness 80 μm) and non-woven fabric (trade name “HOP-60HCF” manufactured by Hirose Paper Co., Ltd.), core: A laminate (PTFE porous membrane / nonwoven fabric, thickness: 191 μm) obtained by thermally bonding polypropylene / sheath: polyethylene, basis weight 60 g / m ² , thickness 160 μm) with a heating roll at 145 ° C. It used for evaluation (1)-(4). The results are shown in Table 1.

As is apparent from Table 1, according to the present invention, by attaching a metal oxide, wettability is not lost even in high-concentration alkaline water, and it contributes to hydrogen generation at low electrolysis voltage in alkaline water electrolysis. The resulting ion permeable membrane can be obtained. Moreover, the ion-permeable diaphragm of this invention is excellent in durability in alkaline water, can maintain the wettability with respect to alkaline water over a long period of time, and can suppress an increase in electrolytic voltage. In addition, the ion-permeable diaphragm shown in the comparative example cannot maintain wettability in high-temperature and high-concentration alkaline water. In such an ion-permeable diaphragm, the electrolysis voltage increases with time.

The ion-permeable membrane of the present invention can be suitably used as a membrane used in alkaline water electrolysis and a membrane for batteries.

DESCRIPTION OF SYMBOLS 10 Microporous membrane 20 Metal oxide 30

Porous reinforcement

100, 200, 300 Ion permeable diaphragm

Claims

With a microporous membrane,
At least one metal oxide selected from titanium oxide and zirconium oxide is attached to the microporous film.
Ion permeable diaphragm.
The ion permeable membrane according to claim 1, further comprising a porous reinforcement.
The ion permeable membrane according to claim 2, wherein at least one metal oxide selected from titanium oxide and zirconium oxide is attached to the porous reinforcing body.
The microporous membrane is composed of polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, ultrahigh molecular weight polyethylene, high density polyethylene, polypropylene, poly-4-methylpentene-1, polysulfone, or polyethersulfone. The ion-permeable diaphragm according to any one of 1 to 3.
The porous reinforcing body is composed of polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyethylene, ultrahigh molecular weight polyethylene, poly-4-methylpentene-1, polysulfone, polyethersulfone, or polyphenylene sulfide. 5. The ion permeable diaphragm according to any one of 1 to 4.
The microporous membrane or a laminate of the microporous membrane and the porous reinforcing body is immersed in a solution containing a metal fluoride complex and a fluorine ion scavenger, and a metal oxide is added to the microporous membrane or the laminate. Including immersing in alkaline water,
The manufacturing method of the ion-permeable diaphragm in any one of Claim 1 to 5.
The method for producing an ion permeable membrane according to claim 6, comprising performing a heat treatment after depositing a metal oxide on the microporous membrane or the laminate.