Anion conductive film, method for producing anion conductive film, membrane electrode assembly, hydrogen production method, and hydrogen production system

Abstract

The present invention pertains to: an anion conductive film which includes a porous base material and an anion conductive polymer that is disposed, in addition to being provided inside of pores of the porous base material, on 70% or more of the area of at least one surface of the porous base material, and in which the anion conductive polymer has a constituent component (I) derived from a polyfunctional polymerizable monomer having a total of 2 or more of at least one atom selected from an oxygen atom, a sulfur atom, and a nitrogen atom at a structural part other than a polymerizable group, and the proportion of the constituent component (I) among all constituent components of the polymer is 50 mol% or more; a method for producing the anion conductive film; a membrane electrode assembly; a hydrogen production method; and a hydrogen production system.

Description

Anion conductive membrane, method for producing anion conductive membrane, membrane electrode assembly, hydrogen production method, and hydrogen production system

[0001] The present invention relates to an anion conductive membrane, a method for producing an anion conductive membrane, a membrane electrode assembly, a hydrogen production method, and a hydrogen production system.

[0002] Hydrogen is a clean energy source that does not emit carbon dioxide and is used, for example, as fuel for fuel cell vehicles and household fuel cells. Water electrolysis (electrolysis) is a well-known method for producing hydrogen. Hydrogen can be produced without carbon dioxide emissions by electrolyzing water using a renewable energy power generation system as a power source. Therefore, hydrogen is increasingly attracting attention as a fundamental energy source for a sustainable society.

[0003] Alkaline water electrolysis (AWE), which uses a highly concentrated alkaline aqueous solution as the electrolyte, is a known practical water electrolysis technology. In alkaline water electrolysis, hydrogen bubbles (2H ２ O + 2e － →H ２ +2OH － ) to the anode side, and also prevents the bubble-like oxygen (4OH) generated at the anode (positive electrode). － →O ２ +2H ２ O+4e － In order to prevent OH from migrating to the cathode side, a gas barrier separator (membrane) is disposed between the cathode and the anode. － Anion exchange membrane water electrolysis (AEMWE) has also been proposed, which uses an anion exchange membrane to improve the efficiency of anion conduction (transfer). AEMWE can conduct anions from the cathode to the anode with high efficiency without using a highly concentrated alkaline aqueous solution as the electrolyte.

[0004] The electrodes (anode catalyst layer and cathode catalyst layer) of an AEMWE are generally formed by mixing a catalyst, in which a precious metal, metal oxide, or the like is optionally supported on a carrier such as carbon, an ionomer that functions as a binder and an ion conductor, and a liquid medium, applying the mixture to a gas-permeable and electronically conductive conductive substrate, and drying the coating to remove the liquid medium. Next, an anion exchange membrane (anion conductive membrane) is sandwiched between the formed anode catalyst layer and cathode catalyst layer, and the anion exchange membrane is bonded to the anode catalyst layer and the cathode catalyst layer by thermocompression bonding under pressure, thereby obtaining a membrane electrode assembly (MEA) for an AEMWE. For example, Patent Document 1 describes the following membrane electrode assembly.

[0005] a membrane electrode assembly for use in a water electrolysis apparatus, the membrane electrode assembly comprising: an electrolyte membrane made of an anion exchange membrane; catalyst layers disposed on both sides of the electrolyte membrane; and a conductive substrate laminated on a surface of the catalyst layer opposite to the surface facing the electrolyte membrane, wherein the catalyst layer comprises a catalyst and an anionic ionomer, at least a portion of the anionic ionomer being in contact with the electrolyte membrane while being embedded in the electrolyte membrane, and the membrane electrode assembly has a mixed region in which the anionic ionomer and the electrolyte membrane are mixed together near a boundary between the catalyst layer and the electrolyte membrane.

[0006] The technology described in Patent Document 1 is said to increase the adhesion between the electrolyte membrane and the catalyst layer, thereby reducing the resistance to the movement of hydroxide ions at the interface between the electrolyte membrane and the catalyst layer, and as a result, reducing the resistance of the membrane electrode assembly.

[0007] Japanese Patent Application Laid-Open No. 2023-104047

[0008] The MEA is required to have low resistance (high anion conductivity) and low gas permeability as basic properties. If hydrogen gas generated on the cathode side by water electrolysis permeates to the anode side, the total amount of hydrogen gas obtained by water electrolysis will decrease, or a recovery device will be required. The MEA is also required to be durable against mechanical forces generated by gas generated by water electrolysis and against changes in operating conditions. In alkaline water electrolysis, it is preferable to be able to perform water decomposition at high temperatures from the standpoint of reaction efficiency, but increased reaction efficiency will increase the amount of gas generated by water electrolysis and cause greater changes in operating conditions. Therefore, it is desirable for the MEA to have durability when water electrolysis is performed at high temperatures for long periods of time (high-temperature continuous current durability).

[0009] The present invention aims to provide a low-resistance anion conductive membrane, in which an MEA formed by sandwiching this anion conductive membrane between a cathode and an anode has excellent gas permeability and durability against continuous high-temperature current flow, and a method for producing the same. The present invention also aims to provide a membrane electrode assembly in which the anion conductive membrane sandwiched between the cathode and the anode has low resistance and excellent gas permeability and durability against continuous current flow, and a hydrogen production method and hydrogen production system using the membrane electrode assembly.

[0010] The above-mentioned problems of the present invention are solved by the following means. [1] An anion conductive membrane comprising a porous substrate and an anion conductive polymer disposed in the pores of the porous substrate and on at least one surface of the porous substrate, covering 70% or more of the surface area, wherein the anion conductive polymer contains a constituent component (I) derived from a polyfunctional polymerizable monomer having a total of two or more atoms of at least one kind of oxygen atom, sulfur atom, and nitrogen atom in a structural part other than a polymerizable group, and the proportion of the constituent component (I) to all constituent components of the anion conductive polymer is 50 mol % or more. [2] The anion conductive membrane according to [1], which has a water retention capacity of 5 mass % or more. [3] The anion conductive membrane according to [1] or [2], wherein the elemental composition of the anion conductive polymer satisfies the following formula (a): [Formula (a)] [total concentration of oxygen, sulfur, and nitrogen (at %)] / [carbon concentration (at %)]≧0.05 [4] The anion conducting membrane according to any one of [1] to [3], wherein the constituent component (I) has any one of the following structural units (i) to (viii): n is an integer of 1 or more. L represents a single bond, an alkylene group, or an arylene group. * represents a linking moiety. [5] The anion conductive membrane according to any one of [1] to [4], wherein the constituent component (I) is a nonionic constituent component. [6] The anion conductive membrane according to any one of [1] to [5], wherein the thickness is 5 to 250 μm. [7] The anion conductive membrane according to any one of [1] to [6], wherein the tensile strength is 10 MPa or more and the elongation at break is 100% or more. [8] The anion conductive membrane according to any one of [1] to [7], wherein the air permeability is 1000 seconds or more. [9] The anion conductive membrane according to any one of [1] to [8], wherein the porosity of the porous substrate is 40 to 80%.

[10] The anion conducting membrane according to any one of [1] to [9], wherein the porous substrate has a tensile strength of 10 MPa or more and a breaking elongation of 100% or more.

[11] The anion conducting membrane according to any one of [1] to

[10] , wherein a constituent material of the porous substrate contains a hydrocarbon polymer.

[12] A method for producing the anion conductive membrane according to any one of [1] to

[10] , comprising: impregnating a porous substrate with a polymerizable monomer-containing liquid containing 50 mol % or more of polyfunctional polymerizable monomers, each polyfunctional polymerizable monomer having a total of two or more atoms of at least one of oxygen, sulfur, and nitrogen atoms in structural moieties other than polymerizable groups, followed by polymerizing the polymerizable monomers; placing a masking material having at least one opening on one surface of the porous substrate after the polymerization reaction; applying the polymerizable monomer-containing liquid to the masking material; polymerizing the polymerizable monomers applied to the masking material; and removing the masking material, thereby disposing an anion conductive polymer containing the component (I) derived from the polyfunctional polymerizable monomer in the pores of the porous substrate and over 70% or more of the surface area.

[13] A method for producing the anion conductive membrane according to

[12] , wherein the polymerizable monomer-containing liquid has a solids content of 30 mass % or more.

[14] A membrane electrode assembly having a structure in which a cathode catalyst layer, the anion conductive membrane according to any one of [1] to

[11] , and an anode catalyst layer are laminated in this order.

[15] A hydrogen production method using the membrane electrode assembly according to

[14] .

[16] A hydrogen production system comprising the membrane electrode assembly according to

[14] .

[0011] In the description of the present invention, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0012] The anion conductive membrane of the present invention has low resistance. An MEA formed by sandwiching this anion conductive membrane between a cathode and an anode has excellent gas permeability and durability allowing continuous current flow even at high temperatures of about 80°C. The anion conductive membrane can be obtained by the method for producing an anion conductive membrane of the present invention. The membrane electrode assembly of the present invention has an anion conductive membrane sandwiched between a cathode and an anode that has low resistance, and the membrane electrode assembly has excellent gas permeability and durability for continuous current flow at high temperatures. The hydrogen production method and hydrogen production system of the present invention use an anion conductive membrane or membrane electrode assembly that has the above-mentioned properties, and can produce hydrogen even by continuous current flow at high temperatures.

[0013] Fig. 1 is a schematic diagram showing an outline of one embodiment of a method for producing an anion conductive membrane, and Fig. 2 is a longitudinal sectional view showing a schematic basic layer structure of one embodiment of a membrane electrode assembly according to the present invention.

[0014] [Anion Conducting Membrane] The anion conducting membrane of the present invention can be widely used as an anion conducting membrane in, for example, water electrolysis, fuel cells, toluene electrolytic reduction, carbon dioxide reduction, etc. In particular, the anion conducting membrane of the present invention is suitable as a diaphragm separating an anode and a cathode in water electrolysis. The anion conducting membrane of the present invention has anion conductivity and low resistance. The ions conducted in the anion conducting membrane are preferably hydroxy ions.

[0015] In the present invention, "having anion conductivity" means that the ionic conductivity obtained by the following method is 0.1 mS / cm or more. -Ionic Conductivity- A 10 mm x 50 mm rectangular test piece is clamped between an ElectroChem BT-115 or a jig (electrode attachment) described in Electrochemistry, Vol. 85, pages 40-44, and AC impedance is measured by the four-terminal method. This AC impedance measurement is performed in a 1 M KOH aqueous solution heated to 45°C, at a voltage of 10 mV and a frequency in the range of 1 MHz to 0.1 Hz. The intercept (an extrapolated value is also acceptable) on the real axis of the Nyquist plot is taken as the resistance value R of the test piece, and the ionic conductivity σ is calculated from the following formula. Ion conductivity σ (S / cm) = D (cm) / (W (cm) × T (cm) × resistance value R (Ω)), D: length (cm) of test piece, W: width (cm) of test piece, T: thickness (cm) of test piece. The anion conductivity of the anion conductive membrane of the present invention is preferably 0.1 mS / cm to 10 S / cm, more preferably 10 mS / cm to 1 S / cm, and even more preferably 10 mS / cm to 500 mS / cm.

[0016] The anion conductive membrane of the present invention comprises a porous substrate and an anion conductive polymer disposed (e.g., exposed, attached, or deposited) within the pores of the porous substrate and covering 70% or more of the area of ​​at least one surface of the porous substrate. One of the two surfaces of the porous substrate is designated as α, and the surface opposite to surface α is designated as β. The anion conductive polymer may be disposed within the pores of the porous substrate and 70% or more of the area of ​​at least one surface of the porous substrate (assuming surface α), and there are no particular restrictions on the area of ​​the anion conductive polymer disposed on surface β of the porous substrate opposite surface α. Surface β of the porous substrate opposite surface α may not contain any anion conductive polymer, and the anion conductive polymer may be disposed on 70% or more of the area of ​​each of the two surfaces α and β of the porous substrate. Therefore, for example, when an anion conductive polymer is disposed over 70% of the area of ​​one surface α of the porous substrate, even if an anion conductive polymer is disposed over 20% of the area of ​​the surface β of the porous substrate opposite to this surface α, or even if an anion conductive polymer is disposed over 70% of the area of ​​the surface β of the porous substrate opposite to this surface α, it is within the scope of the present invention. Also, when an anion conductive polymer is disposed over 60% of the area of ​​one surface α of the porous substrate, even if an anion conductive polymer is disposed over 60% of the area of ​​the surface β of the porous substrate opposite to this surface α, it does not satisfy the provisions of the present invention. Here, "surface of the porous substrate" means the widest surface (main surface) of the porous substrate. "Surface area of ​​the porous substrate" means the area of ​​the main surface of the porous substrate. Therefore, the area of ​​one surface α of the porous substrate means the area of ​​the porous substrate when one main plane of the porous substrate is viewed in plan. Assuming that no anion conductive polymer is disposed on a certain surface α of the porous substrate (for example, the entire surface α of the porous substrate is exposed), the "area of ​​surface α of the porous substrate" means the area including both the pore portions (openings) and non-pore portions of the porous substrate (in other words, it means the area of ​​surface α of the porous substrate when it is assumed that the porous substrate has no pores and is solid).When the porous substrate has holes at the end when viewed in plan, and the end has unevenness due to the holes (for example, the end on the front side of the main surface of the porous substrate 1a shown in FIG. 1), a virtual line is drawn that is assumed when there are no holes, and the end is determined by the virtual line. This end is determined on four sides as necessary, and the area surrounded by the virtual line is the "area of ​​the surface α of the porous substrate". The area of ​​the surface α of the porous substrate is the area including the part where the anion conductive polymer is disposed and the part where the anion conductive polymer is not disposed when there are parts on the surface of the porous substrate where the anion conductive polymer is disposed, and when the anion conductive polymer is disposed on 100% of the area of ​​the surface α of the porous substrate, it is the same as the area of ​​the part where the anion conductive polymer is disposed. When the anion conductive polymer is not disposed on the surface α of the porous substrate, it is the same as the surface area of ​​the porous substrate. In the anion conductive membrane of the present invention, a network of an anion conductive polymer derived from a polyfunctional polymerizable monomer is formed not only within the pores of the porous substrate but also over a wide area, i.e., 70% or more of the area of ​​at least one surface of the porous substrate. By controlling the arrangement of the anion conductive polymer on the surface of the porous substrate in addition to within the pores of the porous substrate in this manner, it is believed that the resistance of the anion conductive membrane can be reduced and the durability of a membrane-electrode assembly using the anion conductive membrane to undergo continuous current application at high temperatures can be improved.

[0017] The ratio of the area of ​​the anion-conductive polymer to the area of ​​one surface of the porous substrate (also referred to as the "polymer area ratio") is preferably 70 to 100%, more preferably 75 to 95%, even more preferably 75 to 90%, and particularly preferably 80 to 90%. In the present invention, the area of ​​the anion-conductive polymer on the surface of the porous substrate is the sum of the area of ​​the anion-conductive polymer exposed on the surface of the porous substrate at the same height as the surface and the area of ​​the anion-conductive polymer arranged convexly relative to the surface of the porous substrate. This does not include the area of ​​the anion-conductive polymer arranged on the surface of the porous substrate at a position lower than the surface. The ratio of the area of ​​the anion-conductive polymer on the surface of the porous substrate can be specifically measured by the method described in the Examples.

[0018] <Anion-Conductive Polymer> The anion-conductive polymer has a specific amount of a constituent component with a specific structure. Specifically, the anion-conductive polymer contains 50 mol% or more of a constituent component (I) derived from a polyfunctional polymerizable monomer (hereinafter simply referred to as "polyfunctional polymerizable monomer IA") having a total of two or more atoms of at least one type of atom selected from oxygen atoms, sulfur atoms, and nitrogen atoms (hereinafter, these three atoms are collectively referred to as "heteroatoms") in a structural portion other than the polymerizable group. That is, the anion-conductive polymer is a polymer obtained by polymerizing a polymerizable monomer-containing solution containing 50 mol% or more of the polyfunctional polymerizable monomer IA among all the polymerizable monomers. This polymerization forms a three-dimensional network structure to produce the anion-conductive polymer. In the anion-conductive polymer, the polymerizable groups of the polyfunctional polymerizable monomer are usually polymerized, but some polymerizable groups that have not been polymerized may also be included. The anion conductive polymer having the above-mentioned component (I) exhibits excellent anion conductivity because the structural portion having the heteroatom effectively increases the polarity of the polymer, allowing it to stably retain more water.

[0019] The elemental composition of the anion-conducting polymer preferably satisfies the following formula (a), more preferably the following formula (a-1), even more preferably the following formula (a-2), and even more preferably the following formula (a-3): Increasing the proportion of heteroelements can impart higher anion conductivity to the anion-conducting polymer or an anion-conducting membrane containing this polymer. [Formula (a)] [total of the concentrations of oxygen, sulfur and nitrogen elements (at%)] / [carbon element concentration (at%)] ≧ 0.05 [Formula (a-1)] 50.00 ≧ [total of the concentrations of oxygen, sulfur and nitrogen elements (at%)] / [carbon element concentration (at%)] ≧ 0.06 [Formula (a-2)] 40.00 ≧ [total of the concentrations of oxygen, sulfur and nitrogen elements (at%)] / [carbon element concentration (at%)] ≧ 0.07 [Formula (a-3)] 38.00 ≧ [total of the concentrations of oxygen, sulfur and nitrogen elements (at%)] / [carbon element concentration (at%)] ≧ 0.08 The element concentration (at%) of each element means the element concentration of each element, which is the total of 100.00 at% of the element concentration of all elements in the anion conductive polymer. The concentration (at%) of each element contained in the anion conductive polymer can be measured using an organic elemental analyzer.

[0020] The polyfunctional polymerizable monomer IA from which the above-mentioned component (I) is derived will now be described. This polyfunctional polymerizable monomer IA has a polymerizable group and a structural portion other than this polymerizable group.

[0021] In the present invention, the term "polyfunctional polymerizable monomer" refers to a monomer having two or more polymerizable groups in one molecule. In other words, "polyfunctional" refers to having two or more polymerizable groups in one molecule. When the polymerizable group is a chain-polymerizable group, the polyfunctional polymerizable monomer IA is preferably a divalent to hexavalent polyfunctional polymerizable monomer (i.e., a monomer having 2 to 6 chain-polymerizable groups in one molecule), and more preferably a divalent to tetravalent polyfunctional polymerizable monomer. When the polymerizable group is a step-polymerizable group, the polyfunctional polymerizable monomer IA is preferably a divalent to hexavalent polyfunctional polymerizable monomer (i.e., a monomer having 2 to 6 step-polymerizable groups in one molecule), more preferably a divalent to pentavalent polyfunctional polymerizable monomer, even more preferably a divalent to tetravalent polyfunctional polymerizable monomer, and particularly preferably a divalent to trivalent polyfunctional polymerizable monomer. Use of a polyfunctional polymerizable monomer tends to result in more crosslinked structures being formed in the resulting polymer, making it possible to form a denser film, compared to the case where a monofunctional polymerizable monomer is used.

[0022] The polymerizable group of the polyfunctional polymerizable monomer IA is not particularly limited as long as it can cause a polymerization reaction, and may be a chain polymerizable group (e.g., a vinyl group (CH ２ ═CH—), vinyl ether group (CH ２ ═CH—O—), vinyl thioether group (CH ２ =CH-S-), acryloyl group (CH ２ ═CH—C(═O)—), methacryloyl group (CH ２ =C(CH ３)-C(═O)-) and derivatives thereof; cyclic ether groups such as an epoxy group (oxiranyl group) or an oxetanyl group); and groups capable of step-growth polymerization include groups that undergo condensation polymerization or polyaddition (hydroxy group, unsubstituted amino group, carboxy group, sulfo group, isocyanate group, acid anhydride group, etc.). The polyfunctional polymerizable monomer IA preferably has two or more chain-polymerizable groups. The polyfunctional polymerizable monomer IA may also have both a chain-polymerizable group and a step-growth polymerizable group. It is also preferable that the polyfunctional polymerizable monomer IA has two or more chain-polymerizable groups and does not have a step-growth polymerizable group. In the present invention, the term "step-growth polymerizable group" refers to a group that reacts with another group to undergo step-growth polymerization under the polymerization reaction conditions of the polyfunctional polymerizable monomer IA for obtaining an anion-conducting polymer. That is, under these polymerization reaction conditions, for example, if the above-mentioned "other groups" are not present and step-growth polymerization cannot occur (i.e., if they remain as unreacted groups in the resulting anion-conducting polymer), even if the polyfunctional polymerizable monomer IA has groups listed as groups capable of step-growth polymerization, such as the above-mentioned hydroxy group, unsubstituted amino group, carboxy group, sulfo group, isocyanate group, and acid anhydride group, these groups are not "step-growth polymerizable groups." Even if a group is listed as a group capable of step-growth polymerization, if step-growth polymerization cannot occur under the above-mentioned polymerization reaction conditions, the oxygen atom, nitrogen atom, etc. constituting this group constitutes a heteroatom present in a structural part other than the polymerizable group of the polyfunctional polymerizable monomer IA.

[0023] The "polymerizable group" is preferably a group selected from a vinyl group, a vinyl ether group, a vinyl thioether group, an acryloyl group, a methacryloyl group, an epoxy group, and an oxetanyl group, and more preferably a group selected from a vinyl group, an acryloyl group, a methacryloyl group, and an epoxy group. When the polyfunctional polymerizable monomer IA has a styryl group, the "polymerizable group" is a vinyl group. That is, the benzene ring constituting the styryl group constitutes the "structural moiety other than the polymerizable group" defined in the present invention. Similarly, for groups containing a vinyl group other than a vinyl ether group, a vinyl thioether group, an acryloyl group, and a methacryloyl group, the polymerizable group is the vinyl group, and the portion other than the vinyl group constitutes the "structural moiety other than the polymerizable group" defined in the present invention. On the other hand, in the present invention, the chain-polymerizable groups, such as the ether group (-O-) possessed by the vinyl ether group, the thioether group (-S-) possessed by the vinyl thioether group, and the carbonyl group (-C(=O)-) possessed by the acryloyl group and the methacryloyl group, as well as the heteroatoms contained in the sequentially polymerizable groups, such as the hydroxy group, the unsubstituted amino group, the carboxy group, the isocyanate group, the sulfo group, and the acid anhydride, are all considered to be part of the structure of the "polymerizable group" possessed by the polyfunctional polymerizable monomer IA. Therefore, the heteroatoms constituting these polymerizable groups are not atoms constituting the "structural moiety other than the polymerizable group" defined in the present invention.

[0024] As described above, the polyfunctional polymerizable monomer IA has a total of two or more atoms of at least one of oxygen atoms, sulfur atoms, and nitrogen atoms in the structural portion other than the polymerizable group (i.e., the total number of oxygen atoms, sulfur atoms, and nitrogen atoms contained in the structural portion other than the polymerizable group is two or more). The combination of these atoms is not particularly limited, and may be a structure having two or more oxygen atoms in the structural portion other than the polymerizable group and no sulfur atoms and no nitrogen atoms, a structure having two or more sulfur atoms in the structural portion other than the polymerizable group and no oxygen atoms and no nitrogen atoms, or a structure having two or more nitrogen atoms in the structural portion other than the polymerizable group and no oxygen atoms and no sulfur atoms. In addition, two or more different types of heteroatoms may be combined to have two or more (for example, a structure having one sulfur atom and one oxygen atom). The total number of oxygen atoms, sulfur atoms, and nitrogen atoms contained in the structural moieties other than the polymerizable group of the polyfunctional polymerizable monomer IA is preferably 2 to 160, more preferably 2 to 140, even more preferably 4 to 100, still more preferably 6 to 80, and particularly preferably 8 to 60, although this depends on the size of the structural moieties other than the polymerizable group.

[0025] The structural portion of the polyfunctional polymerizable monomer IA other than the polymerizable group typically contains atoms other than oxygen, sulfur, and nitrogen atoms. The atoms other than oxygen, sulfur, and nitrogen atoms contained in this structural portion are not particularly limited. The atoms other than oxygen, sulfur, and nitrogen atoms contained in this structural portion are typically carbon and hydrogen atoms. Furthermore, when this structural portion has a cationic or anionic structure, it may contain atoms other than oxygen, sulfur, and nitrogen atoms as counter ions. For example, when the structural portion other than the polymerizable group of the polyfunctional polymerizable monomer IA is a cationic structure having a quaternary ammonium group, it may contain a halogen ion, hydroxy ion, carbonate ion, or the like as counter ions. It is preferable that the polyfunctional polymerizable monomer IA does not contain fluorine atoms in its structure. The absence of fluorine atoms allows for both high anionic conductivity and high gas barrier properties to be achieved.

[0026] The structural portion of the polyfunctional polymerizable monomer IA other than the polymerizable group may be linear, may have a branched structure, or may have a cyclic structure.

[0027] In the structural portion other than the polymerizable group of the polyfunctional polymerizable monomer IA, the number of atoms constituting the shortest link structure connecting two adjacent heteroatoms is preferably 6 or less, more preferably 5 or less, even more preferably 4 or less, and even more preferably 3 or less. For example, in structures (i) and (ii) described below, the atom constituting the shortest link structure between two adjacent oxygen atoms is a carbon atom, and the number of atoms (number of carbon atoms) constituting the shortest link structure is 2. In addition, in structure (iii), the atom constituting the shortest link structure between two adjacent oxygen atoms is a carbon atom, and the number of atoms (number of carbon atoms) constituting the shortest link structure is 1. In addition, in structure (iv), when L is phenylene in which the two linking sites are in a para-position relationship with respect to each other, the atom constituting the shortest link structure between the sulfur atom and oxygen atom adjacent to each other via this phenylene is a carbon atom, and the number of atoms (number of carbon atoms) constituting the shortest link structure is 4. In addition, in structure (iv), when (-S(=O) ２ There are no atoms between the two adjacent heteroatoms in the (-S(=O) ２ In the structure (v), the number of atoms constituting the above-mentioned "shortest connected structure" is 0. In structures (v) to (vii), the atom constituting the shortest connected structure between two nitrogen atoms is a carbon atom, and the number of atoms (number of carbon atoms) constituting the shortest connected structure is 2. In structure (viii), the atom constituting the shortest connected structure between two nitrogen atoms is a carbon atom, and the number of atoms (number of carbon atoms) constituting the shortest connected structure is 6.

[0028] The structural portion of the polyfunctional polymerizable monomer IA other than the polymerizable group has two or more groups selected from oxygen atoms, sulfur atoms, and nitrogen atoms, thereby forming a highly polar structure. Specific examples of the structure having a total of two or more atoms of at least one kind of oxygen atoms, sulfur atoms, and nitrogen atoms that the structural portion has include, for example, a polyalkyleneoxy structure, a carbonate structure (—O—C(═O)—O—), a sulfonyl group (—S(═O) ２ a structure having one or more sulfonyl groups (-S(=O) ２ -) and an ether group (-O-) (for example, -O-(CH ２ )２ -S(=O) ２ - (CH ２ ) ２ -O-, -(CH ２ ) ２ -O-(CH ２ ) ２ -S(=O) ２ - (CH ２ ) ２ -O-(CH ２ ) ２ -), a structure having two or more imino groups (for example, a polyethyleneimine structure), a structure having two or more quaternary ammonium groups, etc. When the polyfunctional polymerizable monomer IA has two or more groups selected from oxygen atoms, sulfur atoms, and nitrogen atoms in a structural portion other than the polymerizable group, a highly polar structure is formed, and an anion-conducting polymer obtained by polymerizing this structure or an anion-conducting membrane containing this polymer can retain more water and have higher anion conductivity.

[0029] The chemical formula weight of the structural portion other than the polymerizable groups of the polyfunctional polymerizable monomer IA is preferably 30 to 4,000, more preferably 50 to 3,000, even more preferably 100 to 2,000, and particularly preferably 100 to 1,000. The value obtained by dividing the "chemical formula weight of the structural portion other than the polymerizable groups" by the "total number of oxygen atoms, sulfur atoms, and nitrogen atoms contained in the structural portion other than the polymerizable groups" ("chemical formula weight of the structural portion other than the polymerizable groups" / "total number of oxygen atoms, sulfur atoms, and nitrogen atoms contained in the structural portion other than the polymerizable groups") of the polyfunctional polymerizable monomer IA is preferably 2 to 100, more preferably 2 to 80, even more preferably 4 to 60, and particularly preferably 5 to 50. The molecular weight of the polyfunctional polymerizable monomer IA is preferably 150 to 5,000, more preferably 180 to 4,500, and even more preferably 200 to 3,000.

[0030] The polyfunctional polymerizable monomer IA may have, in a structural portion other than the polymerizable group, at least one of the following structural portions (i) to (viii).

[0031]

[0032] In the above structural portions (i) to (iii) and (vii), n is an integer of 1 or more, preferably 6 or more. n is preferably 1 to 50, more preferably 2 to 35, even more preferably 3 to 35, still more preferably 4 to 30, still more preferably 5 to 25, still more preferably 6 to 25, and particularly preferably 6 to 25.

[0033] L represents a single bond, an alkylene group, or an arylene group. When L represents an alkylene group, the alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, even more preferably 1 to 3 carbon atoms, and still more preferably 1 or 2 carbon atoms. When L represents an arylene group, the arylene group preferably has 6 to 18 carbon atoms, more preferably 6 to 14 carbon atoms, and still more preferably 6 to 10 carbon atoms. The arylene group is preferably a phenylene group.

[0034] * indicates the linkage site to other structures.

[0035] The structural moiety represented by formula (iv) is more preferably a structural moiety represented by the following formula (ix).

[0036]

[0037] The above-mentioned constituent component (I) (constituent unit derived from polyfunctional polymerizable monomer IA) of the anion conductive polymer is preferably a nonionic constituent component from the viewpoint of durability against high-temperature continuous operation under alkaline conditions. For example, the constituent component (I) preferably has at least one of the above-mentioned structural units (i) to (iv), and more preferably has the structural unit (i) or (ii). It is more preferable that the constituent component (I) has the structural unit (i), and n is 6 or greater.

[0038] The anion conductive polymer can have one or more types of constituent (I). Here, the structural unit (vii) has one nitrogen atom in the structure enclosed in parentheses, but when the constituent (I) has only the structural unit (vii), n in the structural unit (vii) is an integer of 2 or more, and when the constituent (I) has any of the structural units (i) to (vi) and (viii) in addition to the structural unit (vii), n in the structural unit (vii) is an integer of 1 or more.

[0039] Preferable specific examples of the polyfunctional polymerizable monomer IA are shown below, where n is an integer of 1 or more. In the preferable specific examples of the polyfunctional polymerizable monomer IA, the hydroxy ion may be a halogen ion (e.g., a chloride ion) or a carbonate ion.

[0040]

[0041]

[0042] The anion conductive polymer may be a polymer composed of component (I), or may contain, in addition to component (I), component (II) derived from a monomer other than the polyfunctional polymerizable monomer IA. The component (II) can be appropriately employed as long as it does not impair the effects of the present invention. Examples include, but are not limited to, components derived from monofunctional or polyfunctional polymerizable monomers having one heteroatom in the structural portion other than the polymerizable group, components derived from monofunctional polymerizable monomers having a total of two or more heteroatoms of at least one type in the structural portion other than the polymerizable group, and components derived from monofunctional or polyfunctional polymerizable monomers having no heteroatoms in the structural portion other than the polymerizable group. The polymerizable group that can be adopted by the polymerizable monomer from which component (II) is derived is the same as the polymerizable group possessed by the polyfunctional polymerizable monomer IA, and the preferred form of the polymerizable group is also the same. The polymerizable group that can be adopted by the polymerizable monomer from which component (II) is derived is a polymerizable group that can undergo a polymerization reaction with the polymerizable group possessed by the polyfunctional polymerizable monomer IA.

[0043] The molecular weight of the monomer from which component (II) is derived is preferably 80 to 1,000, more preferably 90 to 500, and even more preferably 100 to 300.

[0044] As component (II), a structure having an aryl group is preferred, and the aryl group may further have a substituent. Of these, component (II) is preferably a structure having a benzene ring, and more preferably a structure having one benzene ring. As the substituent that the aryl group may have, a group having an ammonium group, a group having a primary to tertiary amine group, etc. are preferred.

[0045] The proportion of the component (I) in all the components of the anion conductive polymer is 50 mol% or more. The proportion of the component (I) in all the components of the anion conductive polymer is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, may be 90 mol% or more, or may be 95 mol% or more, and all the components of the anion conductive polymer may be the component (I). By increasing the proportion of the component (I), gas permeability can be further reduced.

[0046] The anion-conductive polymer can retain a large amount of water due to the highly polar structure of component (I). The water retention capacity of the anion-conductive polymer is preferably 5% by mass or more, more preferably 5 to 30% by mass, more preferably 5 to 27% by mass, even more preferably 10 to 27% by mass, and particularly preferably 18 to 25% by mass. The water retention capacity of the anion-conductive polymer can be measured in the same manner as in the evaluation of the water retention capacity of the anion-conductive membrane described in the Examples. When measuring the water retention capacity of the anion-conductive polymer, a 50 μm-thick film consisting of the anion-conductive polymer alone can be obtained as a sample by sandwiching a polymerizable monomer-containing liquid between two PET films and curing it without using a porous substrate.

[0047] <Porous substrate> The porous substrate is not particularly limited as long as it has pores that allow water and ions to pass through. The porous substrate preferably has a large number of fine pores that penetrate from the front surface to the back surface. For example, a porous substrate that can be used as a separator for water electrolysis can be used. The constituent material of the porous substrate preferably contains a resin. Examples of constituent materials of the porous substrate include hydrocarbon polymers (preferably polyolefins, more preferably polyethylene or polypropylene), fluoropolymers (polytetrafluoroethylene, etc.), polystyrene, cellulose, polyacrylonitrile, ceramics, etc., and it is preferable to use a hydrocarbon polymer. The porous substrate may be any substrate with a porous structure. For example, it may be a membrane (porous membrane) formed by forming a resin into a film and stretching it to form pores, or it may be a woven fabric or a nonwoven fabric. When the porous substrate is a porous membrane, the porous substrate may be manufactured by a dry method or a wet method, and it is preferable that it is manufactured by a dry method. Here, dry method is the method of forming molten resin into a film, heat treating it, and then stretching it to form pores, and wet method is the method of melting resin and plasticizer (solvent), forming it into a film, stretching it, and then extracting plasticizer to form pores.In the present invention, porous substrate is preferably polyethylene porous membrane, polypropylene porous membrane, polyethylene nonwoven fabric or polytetrafluoroethylene nonwoven fabric, and more preferably polyethylene porous membrane.

[0048] The thickness of the porous substrate is not particularly limited. The thickness of the porous substrate is preferably a thickness that allows an anion conductive membrane to be obtained that is 5 μm or more and 300 μm or less, more preferably 5 μm or more and 250 μm or less. Therefore, the thickness of the porous substrate is preferably 5 μm or more and 150 μm or less, more preferably 6 μm or more and 100 μm or less, even more preferably 6 μm or more and 90 μm or less, even more preferably 7 μm or more and 70 μm or less, even more preferably 7 μm or more and 50 μm or less, and even more preferably 10 μm or more and 30 μm or less. The thickness of the porous substrate is measured after drying the porous substrate. A single porous substrate may be used, or multiple porous substrates may be used. When multiple porous substrates are used, it is preferable to select multiple porous substrates so that the total thickness of the multiple porous substrates is equal to or less than the thickness of the desired anion conductive membrane.

[0049] The porosity of the porous substrate is preferably 20 to 80%, more preferably 25 to 80%, even more preferably 30 to 80%, even more preferably 35 to 80%, even more preferably 40 to 80%, even more preferably 45 to 75%, and even more preferably 50 to 70%. The porosity can be measured by the method described in the examples.

[0050] The tensile strength of the porous substrate is preferably 10 MPa or more, more preferably 15 MPa or more, and even more preferably 20 MPa or more. The tensile strength of the porous substrate is usually 400 MPa or less. Therefore, the tensile strength of the porous substrate is preferably 10 to 400 MPa, more preferably 15 to 400 MPa, and even more preferably 20 to 400 MPa. The breaking elongation of the porous substrate is preferably 50% or more, more preferably 70% or more, even more preferably 100% or more, and even more preferably 130% or more. The breaking elongation of the porous substrate is usually 400% or less. Therefore, the breaking elongation of the porous substrate is preferably 50 to 400%, more preferably 70 to 400%, even more preferably 100 to 400%, and even more preferably 130 to 400%. The tensile strength and breaking elongation of the porous substrate can be measured by the method described in the Examples. It is preferable that the porous substrate have both the above tensile strength and breaking elongation. Therefore, it is preferable that the tensile strength is 10 MPa or more and the elongation at break is 100% or more.

[0051] The porous substrate is preferably surface-modified. Surface modification can form a physical or chemical bond with the anion-conductive polymer during synthesis of the anion-conductive polymer, thereby further increasing the adhesion between the anion-conductive polymer and the porous substrate. Examples of surface modification methods include corona treatment and plasma treatment. Corona treatment and plasma treatment can be performed by conventional methods.

[0052] As the porous substrate, for example, the “porous substrate film” and “laminated porous substrate film” described in paragraphs

[0018] to

[0023] of JP-A No. 2018-127506, and the “microporous membrane” described in paragraph

[0022] of JP-A No. 2022-181107 are also suitable.

[0053] The thickness of the anion conductive membrane is preferably 5 to 300 μm, more preferably 5 to 250 μm, even more preferably 10 to 230 μm, still more preferably 15 to 200 μm, still more preferably 20 to 160 μm, still more preferably 20 to 120 μm, still more preferably 20 to 100 μm, and particularly preferably 20 to 80 μm. The thickness of the anion conductive membrane may be 50 to 250 μm or 55 to 230 μm. The thickness of the anion conductive membrane is determined as follows. ２ Select a rectangular area of ​​1 cm and measure the thickness at any 10 points within this rectangular area. ２ Measurements are made at 10 points on each of 10 squares, and the arithmetic average of all the measured values ​​(10 points x 10) is taken as the thickness of the anion-conducting membrane. The thickness of the porous substrate described above is determined in a similar manner. In the present invention, the thickness of the anion-conducting membrane is usually thicker than the thickness of the porous substrate. This is because the anion-conducting polymer is disposed on at least 70% of the area of ​​at least one surface of the porous substrate. However, it is also considered that the thickness of the anion-conducting membrane will be thicker than the thickness of the porous substrate if the anion-conducting polymer is introduced into the internal pores of the porous substrate in an amount greater than the pore ratio (for example, if the anion-conducting polymer is filled in large amounts due to elongation (expansion) of the porous substrate). The thickness of the anion-conducting membrane is measured after drying the anion-conducting membrane to remove moisture.

[0054] The tensile strength of the anion conductive membrane is preferably 10 MPa or more, more preferably 15 MPa or more, and even more preferably 20 MPa or more. The tensile strength of the anion conductive membrane is usually 300 MPa or less. Therefore, the tensile strength of the anion conductive membrane is preferably 10 to 300 MPa, more preferably 15 to 300 MPa, and even more preferably 20 to 300 MPa. The breaking elongation of the anion conductive membrane is preferably 30% or more, more preferably 50% or more, even more preferably 70% or more, and even more preferably 100% or more. The breaking elongation of the anion conductive membrane is usually 400% or less. Therefore, the breaking elongation of the anion conductive membrane is preferably 30 to 400%, more preferably 50 to 400%, even more preferably 70 to 400%, and even more preferably 100 to 400%. The tensile strength and breaking elongation of the anion conductive membrane can be measured by the methods described in the examples. The anion conductive membrane preferably has both the above-mentioned tensile strength and elongation at break, and therefore preferably has a tensile strength of 10 MPa or more and a elongation at break of 100% or more.

[0055] The air permeability of the anion conductive membrane is preferably 500 seconds or more, more preferably 800 seconds or more, even more preferably 1000 seconds or more, still more preferably 10,000 seconds or more, and even more preferably 50,000 seconds or more. The air permeability of the anion conductive membrane is usually 99,999 seconds (measurement limit) or less. The air permeability of the anion conductive membrane is preferably 500 to 99,999 seconds, more preferably 1000 to 99,999 seconds. The air permeability of the anion conductive membrane can be measured by the method described in the Examples. Low air permeability means that it takes a long time for gas to permeate. In other words, the lower the air permeability, the more difficult it is for gas to pass through.

[0056] The water retention capacity of the anion conductive membrane may be 4% by mass or more, and preferably 5% by mass or more. The water retention capacity of the anion conductive membrane is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, even more preferably 20 to 50% by mass, still more preferably 25 to 45% by mass, and even more preferably 30 to 40% by mass. The water retention capacity of the anion conductive membrane can be measured by the method described in the Examples.

[0057] The anion conductive membrane preferably has an overvoltage (1 A overvoltage) of 0.50 V or less, more preferably 0.30 V or less, and even more preferably 0.25 V or less, as measured by the method described in the Examples below. The overvoltage is usually greater than 0.00 V. Therefore, the overvoltage is preferably greater than 0.00 V and 0.50 V or less, more preferably greater than 0.00 V and 0.30 V or less, and even more preferably greater than 0.00 V and 0.25 V. The overvoltage can be measured by the method described in the Examples with the anion conductive membrane incorporated into a water electrolysis cell.

[0058] The anion conductive membrane preferably has a hydrogen gas permeability (permeability of hydrogen gas generated on the cathode side to the anode side) of less than 2.000 vol% (less than 2 vol%), more preferably less than 1.200 vol%, even more preferably less than 1.000 vol%, still more preferably less than 0.500 vol%, even more preferably less than 0.200 vol%, and still more preferably less than 0.100 vol%. The hydrogen gas permeability is usually preferably 0.001 vol% or more. Therefore, the hydrogen gas permeability is preferably 0.001 vol% or more and less than 2.000 vol%, more preferably 0.001 vol% or more and less than 1.200 vol%, even more preferably 0.001 vol% or more and less than 1.000 vol%, still more preferably 0.001 vol% or more and less than 0.500 vol%, still more preferably 0.001 vol% or more and less than 0.200 vol%, and still more preferably 0.001 vol% or more and less than 0.100 vol%. The hydrogen gas permeability can be measured by the method described in the Examples after incorporating the anion conductive membrane into a water electrolysis cell.

[0059] [Method for producing anion conductive membrane] A method for producing anion conductive membrane of the present invention will be described. The method for producing anion conductive membrane of the present invention is not particularly limited as long as the anion conductive membrane of the present invention can be obtained. One embodiment of the method for producing an anion conductive membrane of the present invention includes simultaneously disposing an anion conductive polymer in the pores of the porous substrate and over 70% or more of the area of ​​at least one surface of the porous substrate. Another embodiment of the method for producing an anion conductive membrane of the present invention includes disposing a polymer in the pores of the porous substrate and further disposing the polymer over 70% or more of the area of ​​at least one surface of the porous substrate. A preferred embodiment of the method for producing an anion conductive membrane of the present invention includes impregnating a porous substrate with a polymerizable monomer-containing liquid containing 50 mol % or more of a polyfunctional polymerizable monomer IA, and then polymerizing the polymerizable monomer, thereby disposing an anion conductive polymer containing the polyfunctional polymerizable monomer IA in the pores of the porous substrate and over 70% or more of the area of ​​at least one surface of the porous substrate. Another preferred embodiment of the method for producing an anion conductive membrane of the present invention includes impregnating a porous substrate with a polymerizable monomer-containing liquid containing 50 mol % or more of a polyfunctional polymerizable monomer IA among all polymerizable monomers, polymerizing the polymerizable monomer, placing a mask material on one surface of the porous substrate after the polymerization reaction, applying the polymerizable monomer-containing liquid to the mask material, polymerizing the polymerizable monomer applied to the mask material, and removing the mask material, thereby disposing an anion conductive polymer containing the component (I) derived from the polyfunctional polymerizable monomer IA in the pores of the anion conductive membrane and over 70% or more of the surface area. Figure 1 is a schematic diagram showing an outline of the method for producing an anion conductive membrane. A porous substrate 1a is shown on the left side of Figure 1. The diagram to the right of the arrow in Figure 1 shows an anion conductive membrane 1 obtained by impregnating the porous substrate 1a with the polymerizable monomer-containing liquid and polymerizing it, covering it with a mask material, applying the polymerizable monomer-containing liquid to the mask material, polymerizing it, and then removing the mask material. In this anion conductive membrane 1, the anion conductive polymer 1b is disposed in the pores of the porous substrate 1a and also over 100% of the area of ​​one surface.

[0060] The polymerizable monomers contained in the polymerizable monomer-containing liquid (the polyfunctional polymerizable monomer IA and polymerizable monomers other than the polyfunctional polymerizable monomer IA that are blended as needed) are as described above. In the polymerizable monomer-containing liquid, the proportion of the polyfunctional polymerizable monomer IA in all polymerizable monomers is the same as the "proportion of the above-mentioned component (I) in all constituent components of the anion conductive polymer" described above. That is, the proportion of the polyfunctional polymerizable monomer IA in all polymerizable monomers is 50 mol% or more, preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, may be 90 mol% or more, or may be 95 mol% or more, and all polymerizable monomers may be polyfunctional polymerizable monomer IA.

[0061] The polymerizable monomer-containing liquid may contain a solvent or may not contain a solvent. Examples of solvents include water, isopropyl alcohol, methanol, ethanol, acetonitrile, tetrahydrofuran (THF), etc. A mixture of these may also be used. When a solvent is used, the solid content of the polymerizable monomer-containing liquid is preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, even more preferably 70% by mass or more, and even more preferably 75% by mass or more. It is also preferable that the polymerizable monomer-containing liquid does not contain a solvent.

[0062] The polymerizable monomer-containing liquid may contain a polymerization initiator in addition to the polymerizable monomer. When the polymerizable group of the monomer is a chain-polymerizable group, the polymerizable monomer-containing liquid usually contains a polymerization initiator. The polymerization initiator can be appropriately selected depending on the polymerizable group possessed by the polymerizable monomer. The polymerization initiator is preferably selected from photopolymerization initiators, thermal polymerization initiators, photocationic polymerization initiators, and thermal cationic polymerization initiators, and combinations of these can also be used. The polymerization initiator can be one that is commonly used for polymerizing polymerizable monomers having chain-polymerizable groups. The content of the polymerization initiator in the polymerizable monomer-containing liquid is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, and more preferably 1 to 8 parts by mass, per 100 parts by mass of the total polymerizable monomers.

[0063] The polymerizable monomer-containing liquid may be the same or different when disposing the polymer in the pores of the porous substrate and when depositing the polymer on at least one surface of the porous substrate. From the viewpoint of process cost, it is preferable to use a single polymerizable monomer-containing liquid (containing the same polyfunctional polymerizable monomer IA).

[0064] A preferred embodiment of a method for disposing a polymer in the pores of a porous substrate will be described. The method for impregnating a porous substrate with a polymerizable monomer-containing liquid is not particularly limited. For example, the porous substrate may be immersed in the polymerizable monomer-containing liquid to allow the polymerizable monomer-containing liquid to penetrate at least the pores, or the polymerizable monomer-containing liquid may be sprayed or applied to the porous substrate to allow the polymerizable monomer-containing liquid to penetrate at least the pores. For example, a porous substrate is laid on a resin substrate such as a polyethylene terephthalate (PET) film, and an appropriate amount of polymerizable monomer-containing liquid is placed on top of it. After application with an applicator, another PET film is placed on the porous substrate, and pressure is applied from above the PET film to extrude excess polymerizable monomer-containing liquid, thereby obtaining an impregnated membrane in which the desired amount of polymerizable monomer-containing liquid is impregnated at least into the pores. At this time, depending on the amount of polymerizable monomer-containing liquid extruded by the other PET film, the polymerizable monomer-containing liquid may also adhere to the surface of the porous substrate (particularly the surface opposite the resin substrate).

[0065] The method for polymerizing the polymerizable monomer is not particularly limited and can be appropriately selected depending on the type of polymerizable group possessed by the polymerizable monomer and the type of polymerization initiator. This polymerization reaction forms an anion-conducting polymer having a three-dimensional network structure. In the polymerization reaction, it is preferable to polymerize the polymerizable monomer using at least one of light and heat, and it is more preferable to polymerize the polymerizable monomer using light and heat in order to complete the polymerization reaction more quickly. The light irradiation conditions and heating conditions can be appropriately set depending on the type of polymerizable monomer and the type of polymerization initiator.

[0066] In this way, the polymerizable monomer impregnated in the porous substrate can be polymerized to obtain an anion conductive membrane (hereinafter sometimes referred to as "pore-impregnated membrane") containing an anion conductive polymer at least in the pores of the porous substrate. When the polymerizable monomer-containing liquid is also attached to the surface of the porous substrate, the anion conductive polymer is disposed on the surface of the porous substrate depending on the amount of adhesion. Therefore, by adjusting the amount of adhesion, it is possible to arrange the anion conductive polymer in 70% or more of the area of ​​one surface of the porous substrate, and it is also possible to arrange it in 100%. In addition, when the porous substrate is laid on a resin substrate and then coated and impregnated with a polymerizable monomer-containing liquid, the anion conductive polymer is usually arranged only in the pores on the surface of the porous substrate or around the pores on the surface of the porous substrate on the side that was in contact with the resin substrate (the surface below in the direction of gravity). During the polymerization reaction, a portion of the polymerizable monomer may be chemically bonded to the functional groups on the surface of the porous substrate.

[0067] A preferred embodiment of another method for disposing an anion-conducting polymer on the surface of a porous substrate will be described. A mask material having at least one opening can be used as the mask material. The opening may be one or more. The mask material preferably has many small openings. Examples of mask materials having such openings include a smooth film with openings, a nonwoven fabric, and the like. The material constituting the mask material is not particularly limited, and polyethylene, polyester, and the like can be used. The surface of a porous substrate (preferably a porous substrate after impregnating pores with a polymerizable monomer-containing liquid and polymerizing the film, i.e., an intrapore-impregnated membrane) is covered with the mask material, and the polymerizable monomer-containing liquid is then applied to the mask material. By removing the mask material, the polymerizable monomer-containing liquid can be adhered to part or all of the surface of the porous substrate (the intrapore-impregnated membrane) in a manner that roughly corresponds to the openings in the mask material. Here, "applying the polymerizable monomer-containing liquid to the mask material" means applying the polymerizable monomer-containing liquid to the mask material itself and the openings in the mask material. By applying the polymerizable monomer-containing liquid in this manner, the polymerizable monomer-containing liquid adheres to the surface of the porous substrate located at the openings of the mask material, and does not adhere to the surface of the porous substrate that was covered with the mask material. The polymerization reaction of the polymerizable monomer-containing liquid may be carried out before removing the mask material from the porous substrate, or may be carried out after removing the mask material from the porous substrate. In the present invention, it is preferable to carry out the polymerization reaction and then remove the mask material from the porous substrate. One or more mask materials may be used. The proportion of the area of ​​the anion conductive polymer on one surface of the porous substrate (polymer area ratio) can be controlled by adjusting the opening ratio, porosity, number of mask materials, thickness, etc. of the mask material. For example, by using a mask material with one opening formed in the center that is larger than the surface, the polymer area ratio can be made 100%. Furthermore, by using multiple mask materials with the same porosity in layers, it is possible to achieve a polymer area ratio smaller than that achieved with a single mask material. In another method, it is most convenient to use a mask having the same opening ratio as the desired area ratio.The thickness of the anion conductive membrane can be controlled by adjusting the thickness of the mask material or by using multiple mask materials. As described above, the thickness can also be controlled by the type and application amount of the polymerizable monomer disposed within the pores or on the surface of the porous substrate. For example, when a nonwoven fabric is used as the mask material, the polymerizable monomer-containing liquid that has passed through the interior of the nonwoven fabric typically adheres to the porous substrate, while the polymerizable monomer-containing liquid does not adhere to the portion of the porous substrate where the fiber portion of the nonwoven fabric contacts. Therefore, the anion conductive polymer is arranged in a convex shape on the surface of the porous substrate where the polymerizable monomer-containing liquid that has passed through the interior of the nonwoven fabric adheres. Furthermore, by applying pressure to the nonwoven fabric, the fibers of the nonwoven fabric can be densely packed, and the size of the voids between the fibers of the nonwoven fabric and the porous substrate can be adjusted. Generally, when the pressure on the nonwoven fabric is high, the voids between the fibers of the nonwoven fabric and the porous substrate tend to be small, and the polymer area ratio on the surface of the porous substrate also tends to be small. Furthermore, when a nonwoven fabric is used as a mask material, the amount of the polymerizable monomer-containing liquid that passes through the nonwoven fabric and adheres to the surface of the porous substrate is very small, and therefore the amount of anion-conductive polymer disposed on the surface of the porous substrate is also very small. Therefore, when a nonwoven fabric is used as a mask material, the thickness of the porous substrate has a large effect on the thickness of the anion-conductive membrane.

[0068] The method for polymerizing the polymerizable monomer applied to the mask material is not particularly limited. As with disposing the polymerizable monomer in the pores of the porous substrate, the method can be appropriately selected depending on the type of polymerizable group and polymerization initiator possessed by the polymerizable monomer. The same applies to polymerizing the polymerizable monomer using at least one of light and heat.

[0069] In this way, the polymerizable monomer disposed on the surface of the porous substrate is polymerized to obtain an anion conductive membrane in which the anion conductive polymer is disposed on 70% or more of the area of ​​at least one surface of the porous substrate. By performing the above-described operation on the surface of the porous substrate on both surfaces of the porous substrate, an anion conductive membrane in which the anion conductive polymer is disposed on 70% or more of the area of ​​the two surfaces of the porous substrate can be obtained.

[0070] [Membrane Electrode Assembly] The membrane electrode assembly of the present invention has a structure in which a cathode catalyst layer, an anion conductive membrane of the present invention, and an anode catalyst layer are laminated in this order. In the membrane electrode assembly of the present invention, the surface of the porous substrate of the anion conductive membrane on which the anion conductive polymer is disposed over 70% or more of the surface area may be located on either the cathode catalyst layer or the anode catalyst layer, but is preferably located on the cathode catalyst layer side. In addition to the cathode catalyst layer, the anion conductive membrane of the present invention, and the anode catalyst layer, the membrane electrode assembly may also include a pair of gas diffusion layers on the outer sides of the cathode catalyst layer and the anode catalyst layer. Figure 2 shows a preferred embodiment of the membrane electrode assembly of the present invention. The membrane electrode assembly 4 of Figure 2 has a cathode catalyst layer 2c formed on one surface of an anion conductive membrane 1, an anode catalyst layer 2a formed on the other surface, and a gas diffusion layer 3 formed on each of these catalyst layers on the side opposite the anion conductive membrane 1. The membrane electrode assembly 4 has a layered structure in which a gas diffusion layer 3, a cathode catalyst layer 2c, an anion conductive membrane 1, an anode catalyst layer 2a, and a gas diffusion layer 3 are layered in this order. The anion conductive membrane 1 has a porous substrate and an anion conductive polymer disposed in the pores thereof, but is shown as an integrated layer in FIG. 2 . The anode catalyst layer 2a contains a particulate anode catalyst 21 and an ionomer resin 23 that also functions as a binder, and the anode catalyst 21 is bound by the ionomer resin 23. The cathode catalyst layer 2c contains a particulate cathode catalyst 22 and an ionomer resin 23 that also functions as a binder, and the cathode catalyst 22 is bound by the ionomer resin 23. In FIG. 2 , a bipolar plate 5 is further formed on the surface of each of the two gas diffusion layers 3 of the membrane electrode assembly 4 opposite the catalyst layer, thereby forming a water electrolysis cell 10.

[0071] Each member constituting the membrane electrode assembly will be described below.

[0072] <Cathode Catalyst Layer> The cathode catalyst layer can be a cathode catalyst layer that can be used in a typical membrane electrode assembly. The cathode catalyst layer is preferably a layer containing a cathode catalyst and an ionomer resin. The cathode catalyst layer may be formed by adhering, baking, and firing a catalyst layer onto a metal mesh or net. Corrosion-resistant stainless steel (SUS) or nickel is preferred for the mesh or net. The cathode catalyst may be any catalyst that electrolyzes water to produce hydrogen (gas). Examples of cathode catalysts that can be used include platinum-supported carbon particles, platinum-coated titanium, palladium-supported carbon particles, cobalt glyoxime, and nickel glyoxime. Non-noble metal catalysts such as iron, iron-rare earth, iron-nickel alloys, and nickel may also be used. The cathode catalyst is preferably in particulate form.

[0073] The ionomer resin is preferably anionic ionomer.As the ionomer resin, sulfonated plastic electrolytes such as perfluoroalkanesulfonic acid, sulfonated polyether ketone, sulfonated polyether sulfone, sulfonated polyether ether sulfone, sulfonated polysulfone, sulfonated polysulfide, sulfonated polyphenylene, etc., sulfoalkylated plastic electrolytes such as sulfoalkylated polyether ether ketone, sulfoalkylated polyether sulfone, sulfoalkylated polyether ether sulfone, sulfoalkylated polysulfone, sulfoalkylated polysulfide, sulfoalkylated polyphenylene, etc. can be used.

[0074] The cathode catalyst layer can be formed by preparing an ink for forming a catalyst layer containing a cathode catalyst, an ionomer resin, and, if necessary, a solvent, and applying and drying this ink.

[0075] <Anode Catalyst Layer> The anode catalyst layer can be an anode catalyst layer that can be used in a typical membrane electrode assembly. The anode catalyst layer is preferably a layer containing an anode catalyst and an ionomer resin. The anode catalyst layer may be formed by adhering, baking, and firing a catalyst layer onto a metal mesh or net. Corrosion-resistant materials such as stainless steel or nickel are preferred for the mesh or net. Any anode catalyst can be used as long as it electrolyzes water to produce oxygen and water. Examples of anode catalysts that can be used include iridium oxide, iridium oxide-coated titanium, iridium ruthenium cobalt oxide, iridium ruthenium tin oxide, iridium ruthenium iron oxide, iridium ruthenium nickel oxide, iridium tin oxide, iridium zirconium oxide, ruthenium titanium oxide, ruthenium zirconium oxide, ruthenium tantalum oxide, and ruthenium titanium cerium oxide. Alternatively, non-noble metal catalysts such as nickel, nickel-based alloys, iron, nickel-coated iron, nickel-cobalt oxide, cobalt oxide, lanthanum-doped cobalt oxide, lanthanum strontium cobalt oxide, and zinc cobalt oxide may be used. The anode catalyst is preferably in particulate form. The ionomer resin may be the same as that described for the cathode catalyst layer.

[0076] The anode catalyst layer can be formed by preparing an ink for forming a catalyst layer containing an anode catalyst, an ionomer resin, and, if necessary, a solvent, and applying and drying this ink.

[0077] <Gas Diffusion Layer> The gas diffusion layer can be a layer that can transport gas and moisture and has electronic conductivity. The gas diffusion layer can be a gas diffusion layer that can be used in a normal membrane electrode assembly. Examples of materials that can be used for the gas diffusion layer include porous materials such as carbon fiber nonwoven fabric, carbon paper, carbon plate, stainless steel (SUS) fiber nonwoven fabric, stainless steel sintered compact, titanium (Ti) fiber nonwoven fabric, titanium sintered compact, nickel (Ni) fiber nonwoven fabric, nickel sintered compact, and materials in which each of these substrates is coated with platinum or gold.

[0078] The membrane electrode assembly can be formed by applying a catalyst layer-forming ink to an anion conductive membrane, or by bonding a pre-formed catalyst layer to an anion conductive membrane. When a gas diffusion layer is provided on the membrane electrode assembly, the catalyst layer-forming ink may be applied to one side of the gas diffusion layer to form a catalyst layer-attached gas diffusion layer, which may then be bonded to the anion conductive membrane.

[0079] [Method for producing hydrogen] The method for producing hydrogen of the present invention is the same as a conventional method for producing hydrogen (water electrolysis) except that the membrane electrode assembly of the present invention is used as the membrane electrode assembly. In the method for producing hydrogen of the present invention, since the anion conductive membrane or membrane electrode assembly of the present invention has high anion conductivity, water electrolysis can be performed using not only a high-concentration alkaline aqueous solution but also a lower-concentration alkaline aqueous solution or water.

[0080] [Hydrogen Production System] The hydrogen production system of the present invention is a system (apparatus) suitable for carrying out the hydrogen production method of the present invention. The hydrogen production system of the present invention is similar to a conventional hydrogen production system except that it includes the membrane electrode assembly of the present invention as the membrane electrode assembly. The hydrogen production system of the present invention can be, for example, a water electrolysis system in which the membrane electrode assembly of the present invention is further combined with components used in general water electrolysis, such as bipolar plates.

[0081] The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited thereto.

[0082] [Preparation of Anion Conductive Membrane] Example 1 Anion Conductive Membrane m1 Preparation of Polymerizable Monomer-Containing Liquid x1 Into a 200 mL three-neck flask, 70.0 g of PEG-1 (polyethylene glycol diglycidyl ether (the number of repeating ethyleneoxy units is 9), Denacol EX-830 (trade name), manufactured by Nagase ChemteX Corporation) as a polyfunctional polymerizable monomer was placed, and under yellow light, 4.0 g of PAG1 (diphenyl[4-(phenylthio)phenyl]sulfonium hexafluorophosphate, manufactured by Tokyo Chemical Industry Co., Ltd.) as a polymerization initiator was further added to prepare a polymerizable monomer-containing liquid x1 with a solids content of 100 mass %. - Preparation of anion conductive membrane - Under yellow light, a 15 μm thick, 58% porosity polyethylene porous membrane (manufactured by Toray Industries, Inc., Ceteera (trade name)) (10 cm × 10 cm) was laid as a porous substrate on a 10 μm thick PET film p1, and an appropriate amount of polymerizable monomer-containing liquid x1 was placed on the polyethylene porous membrane and applied with an applicator. After that, another PET film p2 was placed on the coated polyethylene porous membrane, and the excess polymerizable monomer-containing liquid that had not impregnated into the polyethylene porous membrane was extruded to form an impregnated membrane in which the polymerizable monomer-containing liquid x1 had impregnated into the pores of the porous substrate. For this impregnated membrane, 100 mJ / cm at 365 nm was applied. ２ A UV irradiator (EXECURE3000 (trade name), manufactured by HOYA Corporation) adjusted to an integrated light dose of 800 mJ / cm 2 was used. ２UV light was irradiated so that the thickness of the porous impregnated membrane a was 100°C. Thereafter, after heating at 100 °C for 10 minutes, the two PET films p1 and p2 were removed. In this way, an intrapore-impregnated membrane a was formed. The intrapore-impregnated membrane a was placed on the PET film p3, and a 50 μm thick polyethylene nonwoven fabric (manufactured by Hirose Paper Co., Ltd., HOP (trade name), porosity 60%) was placed on the intrapore-impregnated membrane a. An appropriate amount of polymerizable monomer-containing liquid x1 was placed on the polyethylene nonwoven fabric and applied with an applicator, and then another PET film p4 was placed on top. The excess polymerizable monomer-containing liquid x1 that was not impregnated into the polyethylene nonwoven fabric was removed while applying pressure so that the thickness of the nonwoven fabric was 45 μm, forming an impregnated membrane. By this operation, the polymerizable monomer-containing liquid x1 that passed through the inside of the nonwoven fabric adhered to the surface of the porous substrate, and it is believed that the polymerizable monomer-containing liquid x1 did not adhere to the porous substrate where the fiber portion of the nonwoven fabric contacted. For this impregnated membrane, 100 mJ / cm at 365 nm ２ A UV irradiator (EXECURE3000 (trade name), manufactured by HOYA Corporation) adjusted to an integrated light dose of 800 mJ / cm 2 was used. ２ UV light was irradiated so that the thickness of the porous substrate was 100°C. Then, the substrate was heated at 100°C for 10 minutes, and the PET film p4, nonwoven fabric, and PET film p3 were removed in that order. In this way, an anion conductive membrane m1 having a thickness of 28 µm was produced, in which an anion conductive polymer was disposed in the pores of the porous substrate and on 80% of the area of ​​one surface of the porous substrate. In the anion conductive membrane m1, the area of ​​the anion conductive polymer on the surface of the porous substrate opposite to the surface on which the anion conductive polymer was disposed (the surface in contact with the PET film p3) was 60%.

[0083] Example 2 Anion Conductive Membrane m2 An opening (8 cm x 8 cm) was formed in the center of a 20 μm thick polyester film (Lumirror (trade name), manufactured by Toray Industries, Inc., aperture ratio 0%) by punching out the center, and this was used as film f1. An anion conductive membrane m2 was obtained in the same manner as in Example 1, except that the process after obtaining the pore-impregnated membrane a in Example 1 was changed as follows. Specifically, the process is as follows. The pore-impregnated membrane a was placed on a PET film p3. One film f1 was placed on the pore-impregnated membrane a so that its aperture was at the center of the pore-impregnated membrane a, and an appropriate amount of polymerizable monomer-containing liquid x1 was placed on top of the film f1 and applied with an applicator. Excess polymerizable monomer-containing liquid x1 was removed by pushing out the polymerizable monomer-containing liquid x1 from above the film f1 with a metal spatula except for the aperture. This membrane was subjected to 100 mJ / cm at 365 nm. ２ A UV irradiator (EXECURE3000 (trade name), manufactured by HOYA Corporation) adjusted to an integrated light dose of 800 mJ / cm 2 was used. ２ The film was irradiated with UV light so that the cured film was uniform. Then, it was heated at 100 ° C. for 10 minutes. The PET film p3 and film f1 were removed. In the cured film thus obtained, the portions of the cured film corresponding to the openings of film f1 were left, and the portions of the cured film not corresponding to the openings were removed. In this way, an anion conductive membrane m2 having a thickness of 33 μm was prepared, in which an anion conductive polymer was disposed in the pores of the porous substrate and on 100% of the area of ​​one surface of the porous substrate. In the anion conductive membrane m2, the area of ​​the anion conductive polymer occupied 60% of the area of ​​the surface of the porous substrate opposite to the surface on which the anion conductive polymer was disposed (the surface that was in contact with the PET film p3).

[0084] Example 3 Anion Conduction Membrane m3 An anion conduction membrane m3 was obtained in the same manner as in Example 1, except that the process after obtaining the pore-impregnated membrane a in Example 1 was changed as follows. Specifically, it is as follows. The pore-impregnated membrane a was placed on a PET film p3, a 50 μm thick polyethylene nonwoven fabric (HOP (trade name), manufactured by Hirose Paper Co., Ltd., porosity 60%) was placed on the pore-impregnated membrane a, an appropriate amount of polymerizable monomer-containing liquid x1 was placed on the polyethylene nonwoven fabric and applied with an applicator, and then another PET film p4 was placed on top. The excess polymerizable monomer-containing liquid x1 that had not been impregnated into the polyethylene nonwoven fabric was extruded under pressure so that the thickness of the nonwoven fabric became 35 μm, thereby forming an impregnated membrane. This impregnated membrane was subjected to 100 mJ / cm at 365 nm. ２ A UV irradiator (EXECURE3000 (trade name), manufactured by HOYA Corporation) adjusted to an integrated light dose of 800 mJ / cm 2 was used. ２ UV light was irradiated so that the thickness of the porous substrate was 100°C. Then, the substrate was heated at 100°C for 10 minutes, and the PET film p4, nonwoven fabric, and PET film p3 were removed in that order. In this way, an anion conductive membrane m3 having a thickness of 30 µm was prepared, in which an anion conductive polymer was disposed in the pores of the porous substrate and on 70% of the area of ​​one surface of the porous substrate. In addition, in the anion conductive membrane m3, the area of ​​the anion conductive polymer on the surface opposite to the surface on which the anion conductive polymer was disposed of the porous substrate (the surface in contact with the PET film p3) was 60%.

[0085] Example 4 Anion Conductive Membrane m4 In Example 2, instead of the film f1, a 100 μm thick film (manufactured by Toray Industries, Inc., Lumirror) with an opening (8 cm × 8 cm) formed on it was used. In the same manner as in Example 2, except that a film f2 was used, an anion conductive polymer was disposed in the pores of the porous substrate and on 100% of the area of ​​one surface of the porous substrate. A 130 μm thick anion conductive membrane m4 was produced. In the anion conductive membrane m4, the area of ​​the anion conductive polymer on the surface opposite to the surface on which the anion conductive polymer was disposed of the porous substrate (the surface that was in contact with the PET film p3) was 60%.

[0086] Example 5 Anion Conductive Membrane m5 In Example 2, instead of film f1, two 100 μm thick films (manufactured by Toray Industries, Inc., Lumirror (trade name)) were stacked on top of each other to form an opening (8 cm × 8 cm) in film f3. An anion conductive polymer was disposed in the pores of the porous substrate and on 100% of the area of ​​one surface of the porous substrate in the same manner as in Example 2, to produce a 230 μm thick anion conductive membrane m5. In addition, in the anion conductive membrane m5, the area of ​​the anion conductive polymer on the surface of the porous substrate opposite to the surface on which the anion conductive polymer was disposed (the surface that was in contact with the PET film p3) accounted for 60%.

[0087] Example 6 Anion Conductive Membrane m6 In Example 1, a 23 μm thick, 72% porosity polyethylene porous membrane (manufactured by Toray Industries, Inc., Ceteera (trade name)) (no corona treatment) was used as the porous substrate. In the same manner as in Example 1, an anion conductive polymer was disposed in the pores of the porous substrate and on 80% of the area of ​​one surface of the porous substrate. A 35 μm thick anion conductive membrane m6 was obtained. In the anion conductive membrane m6, the area of ​​the anion conductive polymer on the surface of the porous substrate opposite to the surface on which the anion conductive polymer was disposed (the surface that was in contact with the PET film p3) accounted for 60%.

[0088] Example 7 Anion Conductive Membrane m7 In Example 1, an 8 μm thick, 48% porosity polyethylene porous membrane (manufactured by Toray Industries, Inc., Ceteera (trade name)) (no corona treatment) was used as the porous substrate. In the same manner as in Example 1, an anion conductive polymer was disposed in the pores of the porous substrate and on 80% of the area of ​​one surface of the porous substrate. An anion conductive membrane m7 having a thickness of 18 μm was obtained. In the anion conductive membrane m7, the area of ​​the anion conductive polymer on the surface of the porous substrate opposite to the surface on which the anion conductive polymer was disposed (the surface that was in contact with the PET film p3) accounted for 60%.

[0089] Example 8 Anion Conductive Membrane m8 Preparation of Polymerizable Monomer-Containing Liquid x2 29.7 g of PEG-1 (polyethylene glycol diglycidyl ether (number of repeating ethyleneoxy units: 9), Denacol EX-830 (trade name), manufactured by Nagase ChemteX Corporation) and 40.3 g of PEG-2 (polyethylene glycol diglycidyl ether (number of repeating ethyleneoxy units: 4), Denacol EX-821 (trade name), manufactured by Nagase ChemteX Corporation) as polyfunctional polymerizable monomers were placed in a 200 mL three-neck flask, and 4.0 g of PAG1 (diphenyl[4-(phenylthio)phenyl]sulfonium hexafluorophosphate, manufactured by Tokyo Chemical Industry Co., Ltd.) was further added as a polymerization initiator under yellow light to prepare a polymerizable monomer-containing liquid x2 with a solids content of 100% by mass. - Preparation of anion conductive membrane - An anion conductive membrane m8 having a thickness of 28 μm and in which an anion conductive polymer was disposed in the pores of the porous substrate and over 80% of the area of ​​one surface of the porous substrate was obtained in the same manner as in Example 1, except that the polymerizable monomer-containing liquid x2 was used instead of the polymerizable monomer-containing liquid x1 in the preparation of the anion conductive membrane of Example 1. In the anion conductive membrane m8, the area of ​​the anion conductive polymer accounted for 60% of the area of ​​the surface of the porous substrate opposite to the surface on which the anion conductive polymer was disposed (the surface that was in contact with the PET film p3).

[0090] Example 9 Anion Conductive Membrane m9 Preparation of Polymerizable Monomer-Containing Liquid x3 44.4 g of PEG-1 (polyethylene glycol diglycidyl ether (the number of repeating ethyleneoxy units is 9), Denacol EX-830 (trade name), manufactured by Nagase ChemteX Corporation) and 25.6 g of PPG-1 (polypropylene glycol diglycidyl ether (the number of repeating propyleneoxy units is 3), Denacol EX-920 (trade name), manufactured by Nagase ChemteX Corporation) were placed into a 200 mL three-neck flask as polyfunctional polymerizable monomers, and 4.0 g of PAG1 (diphenyl[4-(phenylthio)phenyl]sulfonium hexafluorophosphate, manufactured by Tokyo Chemical Industry Co., Ltd.) was further added as a polymerization initiator under yellow light to prepare a polymerizable monomer-containing liquid x3 with a solids content of 100% by mass. - Preparation of anion conductive membrane - An anion conductive membrane m9 having a thickness of 28 μm and in which an anion conductive polymer was disposed in the pores of the porous substrate and over 80% of the area of ​​one surface of the porous substrate was obtained in the same manner as in Example 8, except that the polymerizable monomer-containing liquid x3 was used instead of the polymerizable monomer-containing liquid x2 in Example 8. In the anion conductive membrane m9, the area of ​​the anion conductive polymer accounted for 60% of the area of ​​the surface of the porous substrate opposite to the surface on which the anion conductive polymer was disposed (the surface that was in contact with the PET film p3).

[0091] Example 10: Anion Conduction Membrane m10 - Preparation of Polymerizable Monomer-Containing Solution x4 - A 200 mL three-neck flask was charged with 10.0 g of pure water, 3.0 g of isopropyl alcohol, and 36.0 g of Monomer m-1 as a polyfunctional polymerizable monomer to prepare a solution. Under yellow light, 0.5 g of 2-hydroxy-2-methylpropiophenone (manufactured by TCI) and 0.5 g of ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate (manufactured by TCI) (collectively referred to as "Initiator 2" in the table) were further added as polymerization initiators to prepare Polymerizable Monomer-Containing Solution x4 with a solids content of 74 mass%. The following compound was used as Monomer m-1. - Preparation of anion conductive membrane - Under yellow light, a 15 μm thick, 58% porosity polyethylene porous membrane (manufactured by Toray Industries, Inc., Ceteera (trade name)) (without corona treatment) was laid as a porous substrate on a 10 μm thick PET film p1, and an appropriate amount of polymerizable monomer-containing liquid x4 was placed on top of it and applied with an applicator. After that, another PET film p2 was placed on top of the coated polyethylene porous membrane, and the excess polymerizable monomer-containing liquid that had not impregnated into the polyethylene porous membrane was extruded, forming an impregnated membrane in which the polymerizable monomer-containing liquid x4 had impregnated into the pores of the porous substrate. This impregnated membrane was subjected to 100 mJ / cm at 365 nm. ２ A UV irradiator (EXECURE3000 (trade name), manufactured by HOYA Corporation) adjusted to an integrated light dose of 800 mJ / cm 2 was used. ２ The monomer was polymerized by irradiating UV light so that the PET film was removed. In this way, an impregnated pore membrane b was formed. The impregnated pore membrane b was placed on a PET film p3, a 50 μm thick polyethylene nonwoven fabric (HOP (trade name), manufactured by Hirose Paper Co., Ltd., porosity 60%) was placed on the impregnated pore membrane b, an appropriate amount of polymerizable monomer-containing liquid x4 was placed on the polyethylene nonwoven fabric and applied with an applicator, and then another PET film p4 was placed on top, and an impregnated membrane was formed by extruding the excess polymerizable monomer-containing liquid that was not impregnated into the polyethylene nonwoven fabric. This impregnated membrane was subjected to 100 mJ / cm at 365 nm. ２ A UV irradiator (EXECURE3000 (trade name), manufactured by HOYA Corporation) adjusted to an integrated light dose of 800 mJ / cm 2 was used. ２ UV light was irradiated so that the PET film p4, nonwoven fabric, and PET film p3 were removed in this order. In this way, an anion conductive membrane m10 having a thickness of 26 μm was produced, in which an anion conductive polymer was disposed in the pores of the porous substrate and on 80% of the area of ​​one surface of the porous substrate. In the anion conductive membrane m10, the area of ​​the anion conductive polymer on the surface of the porous substrate opposite to the surface on which the anion conductive polymer was disposed (the surface that was in contact with the PET film p3) accounted for 60%.

[0092] Example 11 Anion Conduction Membrane m11 Preparation of Polymerizable Monomer-Containing Liquid x5 A polymerizable monomer-containing liquid x5 having a solids content of 100% by mass was prepared in the same manner as in Example 1, except that PEG-3 (polyethylene glycol diglycidyl ether (repeating number of ethyleneoxy units: 13), Denacol EX-841 (trade name), manufactured by Nagase ChemteX Corporation) was used as the polyfunctional polymerizable monomer. Preparation of Anion Conduction Membrane A 230 μm-thick anion conduction membrane m11 was obtained in the same manner as in Example 8, except that the polymerizable monomer-containing liquid x5 was used instead of the polymerizable monomer-containing liquid x2 in Example 8, and a laminate of 15 polyethylene porous membranes (manufactured by Toray Industries, Inc., Ceteera (trade name)) (without corona treatment) having a thickness of 15 μm and a porosity of 58% was used as the porous substrate. In the anion conductive membrane m11, the area of ​​the anion conductive polymer accounted for 60% of the area of ​​the surface of the porous substrate opposite to the surface on which the anion conductive polymer was disposed (the surface that was in contact with the PET film p3).

[0093] Example 12 Anion Conductive Membrane m12 Preparation of Polymerizable Monomer-Containing Liquid x6 Into a 200 mL three-neck flask were placed 16.5 g of PEG-4 (polyethylene glycol diglycidyl ether (the number of repeating ethyleneoxy units is 2), Denacol EX-850 (trade name), manufactured by Nagase ChemteX Corporation) and 53.5 g of PPG-1 (polypropylene glycol diglycidyl ether (the number of repeating propyleneoxy units is 3), Denacol EX-920 (trade name), manufactured by Nagase ChemteX Corporation) as polyfunctional polymerizable monomers, and under yellow light, 4.0 g of PAG1 (diphenyl[4-(phenylthio)phenyl]sulfonium hexafluorophosphate, manufactured by Tokyo Chemical Industry Co., Ltd.) was further added as a polymerization initiator to prepare a polymerizable monomer-containing liquid x6 with a solids content of 100% by mass. - Preparation of anion conductive membrane - An anion conductive membrane m12 having a thickness of 28 μm and in which an anion conductive polymer was disposed in the pores of the porous substrate and over 80% of the area of ​​one surface of the porous substrate was obtained in the same manner as in Example 8, except that the polymerizable monomer-containing liquid x6 was used instead of the polymerizable monomer-containing liquid x2 in Example 8. In the anion conductive membrane m12, the area of ​​the anion conductive polymer accounted for 70% of the area of ​​the surface of the porous substrate opposite to the surface on which the anion conductive polymer was disposed (the surface that had been in contact with the PET film p3).

[0094] Example 13 Anion Conductive Membrane m13 In Example 2, instead of the film f1, two 100 μm thick films (manufactured by Toray Industries, Inc., Lumirror (trade name)) and one 50 μm thick film (manufactured by Toray Industries, Inc., Lumirror (trade name)) were laminated to form an opening (8 cm × 8 cm) in a laminate film. Except for using a film f4, an anion conductive polymer was disposed in the pores of the porous substrate and on 100% of the area of ​​one surface of the porous substrate. A 270 μm thick anion conductive membrane m13 was produced in the same manner as in Example 2. In the anion conductive membrane m13, the area of ​​the anion conductive polymer on the surface opposite to the surface on which the anion conductive polymer was disposed of the porous substrate (the surface that was in contact with the PET film p3) was 60%.

[0095] Comparative Example 1: Anion Conduction Membrane cm1 An anion conduction membrane cm1 was obtained in the same manner as in Example 1, except that the process after obtaining the pore-impregnated membrane a in Example 1 was changed as follows. Specifically, the process is as follows. The pore-impregnated membrane a was placed on a PET film p3, and two 50 μm-thick polyethylene nonwoven fabrics (HOP (trade name), manufactured by Hirose Paper Co., Ltd., porosity 60%) were placed on top of it. An appropriate amount of polymerizable monomer-containing liquid x1 was placed on the polyethylene nonwoven fabrics and applied with an applicator, and then another PET film p4 was placed on top. The excess polymerizable monomer-containing liquid x1 that had not been impregnated into the polyethylene nonwoven fabrics was extruded under pressure so that the total thickness of the two nonwoven fabrics was 60 μm, thereby forming an impregnated membrane. This impregnated membrane was subjected to 100 mJ / cm at 365 nm. ２ A UV irradiator (EXECURE3000 (trade name), manufactured by HOYA Corporation) adjusted to an integrated light dose of 800 mJ / cm 2 was used. ２ UV light was irradiated so that the thickness was 100°C. Then, the substrate was heated at 100°C for 10 minutes, and the PET film p4, nonwoven fabric, and PET film p3 were removed in that order. In this way, an anion conductive membrane cm1 having a thickness of 27 µm was prepared, in which an anion conductive polymer was disposed in the pores of the porous substrate and on 65% of the area of ​​one surface of the porous substrate. In the anion conductive membrane cm1, the area of ​​the anion conductive polymer on the surface opposite to the surface on which the anion conductive polymer was disposed of the porous substrate (the surface in contact with the PET film p3) was 60%.

[0096] Comparative Example 2 Anion Conductive Membrane cm2 Under yellow light, a 15 μm thick, 55% porosity polyethylene porous membrane (manufactured by Toray Industries, Inc., Setira (trade name)) (no corona treatment) was laid on a 10 μm thick PET film p1 as a porous substrate, an appropriate amount of polymerizable monomer-containing liquid x1 was placed on it, and after applying it with an applicator, another PET film p2 was placed on top of the coated polyethylene porous membrane, and the excess polymerizable monomer-containing liquid x1 that had not impregnated into the polyethylene porous membrane was extruded to form an impregnated membrane in which the polymerizable monomer-containing liquid x1 had impregnated into the pores of the porous substrate. The other PET film p2 was removed. Another 15 μm thick, 55% porosity polyethylene porous membrane (manufactured by Toray Industries, Inc., Setira (trade name)) (no corona treatment) was laminated on top of the impregnated membrane. This laminate is a laminate of a porous substrate in which the pores of the porous substrate are impregnated with the polymerizable monomer-containing liquid x1 and a porous substrate in which the pores of the porous substrate are not impregnated with the polymerizable monomer-containing liquid x1. ２ A UV irradiator (EXECURE3000 (trade name), manufactured by HOYA Corporation) adjusted to an integrated light dose of 800 mJ / cm 2 was used. ２ UV light was irradiated so that the thickness was 100°C. Then, the mixture was heated at 100°C for 10 minutes. Furthermore, the PET film p1 was removed. In this way, in the above-mentioned laminated state, an anion conductive polymer was disposed in the pores of the lower porous substrate, but an anion conductive polymer was not disposed in the pores of the upper porous substrate or on the exposed surface. An anion conductive membrane cm2 was thus produced. In the anion conductive membrane cm2, the area of ​​the anion conductive polymer occupied 60% of the area of ​​the surface of the lower porous substrate opposite to the upper porous substrate (the surface that was in contact with the PET film p1).

[0097] The anion conductive membranes obtained above all had an ionic conductivity of 0.1 mS / cm to 10 S / cm. In addition, the proportion of component (I) in the total components of the anion conductive polymer constituting each anion conductive membrane was 100 mol %.

[0098] [Preparation of Ink for Forming Catalyst Layer] <Preparation of Ink b1i for Forming Cathode Catalyst Layer> In a 10 mL vial, 2.9 g of Nafion dispersion (5% Nafion dispersion DE521 (trade name) manufactured by Fujifilm Wako Chemical Co., Ltd.) and 0.34 g of platinum carbon powder (TEC10E50E (trade name) manufactured by Tanaka Kikinzoku Kogyo K.K., platinum content 47% by mass) were mixed, and the mixture was dispersed for 5 minutes at a power of 30 W using an ultrasonic homogenizer UH-300 (trade name, manufactured by SMT Co., Ltd.), cooled at 5°C for 10 minutes, and then dispersed again for 5 minutes at a power of 30 W to prepare ink b1i for forming a cathode catalyst layer.

[0099] [Preparation of Gas Diffusion Layer (GDL) with Catalyst Layer] <Preparation of Gas Diffusion Layer b1 with Cathode Catalyst Layer> The ink b1i for forming a cathode catalyst layer was applied to a carbon fiber nonwoven fabric having a microporous layer (manufactured by SGL, GDL-39BB (product name)) using an applicator so that the platinum coating amount was 0.8 mg / cm. ２ This was allowed to dry naturally to obtain a cathode catalyst layer-attached gas diffusion layer b1.

[0100] [Preparation of Water Electrolysis Cell] <Water Electrolysis Cell 101> The cathode catalyst layer-attached gas diffusion layer b1 and the anode catalyst layer-attached gas diffusion layer (manufactured by Dioxide Material, Anode Electrode for Water Electrolyzer (product name)) prepared above were each cut into 1 cm ２The porous substrate was punched out to the same shape, stacked with the anion conductive membrane m1 sandwiched between them, and pressurized at a surface pressure of 0.5 MPa. The pressurized formed body was sandwiched between Ni bipolar plates having flow channels and constrained with bolts to a confining pressure of 0.5 MPa. The surface of the anion conductive membrane m1 on which 80% of the surface area of ​​the porous substrate was covered with an anion conductive polymer was positioned so as to contact the gas diffusion layer with a cathode catalyst layer. In this manner, a water electrolysis cell 101 was obtained, which has the same layer structure as the water electrolysis cell 10 shown in FIG. 2 , which has a layer structure of bipolar plate-gas diffusion layer-anode catalyst layer-anion conductive membrane-cathode catalyst layer-gas diffusion layer-bipolar plate. This water electrolysis cell 101 has a structure including a membrane electrode assembly (anode catalyst layer-anion conductive membrane-cathode catalyst layer, or gas diffusion layer-anode catalyst layer-anion conductive membrane-cathode catalyst layer-gas diffusion layer).

[0101] <Water electrolysis cells 102 to 113 and c101 to c102> Water electrolysis cells 102 to 113 and c101 to c102 were obtained in the same manner as the preparation of the water electrolysis cell 101, except that the anion conductive membranes m2 to m13 and cm1 to cm2 produced in Examples 2 to 13 and Comparative Examples 1 and 2 were used. In preparing each water electrolysis cell, the surface of the porous substrate on which the anion conductive polymer was more abundant was positioned so as to be in contact with the cathode catalyst layer-equipped gas diffusion layer.

[0102] The anion conductive membrane and water electrolysis cell thus obtained were evaluated as follows.

[0103] [Evaluation of Polymer Area Ratio] The surface (1 cm × 1 cm) of each anion conductive membrane prepared was observed with a laser microscope to obtain a three-dimensional image. The surface area was designated Ar1. In each three-dimensional image obtained, the total area Ar2 was measured, which was the area of ​​the anion conductive polymer located at the same height as the porous substrate surface (reference plane) (exposed at the same height as the surface on the porous substrate surface) and the area of ​​the portion where the anion conductive polymer was located above the reference plane (opposite the porous substrate), and the area ratio of the anion conductive polymer in this surface area Ar1 (Ar2 / Ar1 × 100 (%)) was calculated. In the above measurement, the porous substrate surface (reference plane) was identified using a scanning electron microscope (SEM) image of the cross section of the anion conductive membrane. The composition of the anion conductive membrane surface was also confirmed by energy dispersive X-ray fluorescence analysis (EDX). As the cross-sectional SEM image, an SEM image (observation field: 200 μm × 200 μm) of a cross section obtained by cutting the anion conductive membrane perpendicular to the surface at any 20 points was obtained. In each cross-sectional SEM image, the boundary points between the porous substrate and the anion conductive polymer were identified at any 20 points, and the average line of these 400 boundary points was calculated. The obtained average line was used as the reference plane of the porous substrate in the cross-sectional SEM image. The surface corresponding to the reference plane of the porous substrate in this cross-sectional SEM image was identified by calculating the distance from the end in the three-dimensional image obtained by the laser microscope. In this way, the porous substrate surface (reference plane) was identified. Therefore, the area of ​​the anion conductive polymer arranged in the pores of the porous substrate at the same height as the reference plane or in a convex state at a position higher than the reference plane was counted in the measurement using the laser microscope, but the area of ​​the anion conductive polymer arranged in a concave state at a position lower than the reference plane was not counted in the measurement using the laser microscope. EDX was performed on the entire area of ​​the porous substrate surface to be observed with the laser. When the anion-conductive polymer is disposed over 100% of the surface area of ​​the porous substrate being observed, the composition of the anion-conductive polymer can be confirmed; when the anion-conductive polymer is not disposed on the surface of the porous substrate being observed, the composition of the porous substrate can be confirmed.

[0104] [Evaluation of Air Permeability] The air permeability of the anion conductive membrane was determined as follows. The air permeability (air resistance) of the anion conductive membrane was measured using an Oken air permeability meter (EYO-651MR (trade name), manufactured by Asahi Seiko Co., Ltd.) according to the method described in JIS P8117:2009. The anion conductive membrane was pretreated by leaving it at 25°C and a relative humidity of 45% for 24 hours. The measurement was performed at room temperature (25°C) and a relative humidity of 45%, and the average value of three measurements was determined as the air permeability.

[0105] [Evaluation of Water Retention Capacity] The water retention capacity of the anion conductive membrane was measured as follows. Test pieces measuring 5 cm long x 5 cm wide were cut out from the anion conductive membrane, and measurements were carried out using these test pieces. The weight of the test piece after drying at 60°C under vacuum for 12 hours was designated as WA, and the mass of the test piece after 8 hours in a state where the entire dried test piece was completely immersed in a 1.5 M aqueous potassium hydroxide (KOH) solution was designated as WB. The water retention capacity was calculated using the following formula: Water retention capacity (mass%) = (WB - WA) / WB x 100

[0106] [Evaluation of Porosity of Porous Substrate] The volume of the porous substrate (the volume of the entire porous substrate including the volume of the pores) was calculated as X (cm ３ ), the weight of the porous substrate is W (g), the true density of the porous substrate is d (g / cm ３ ) and X and the theoretical volume Y (cm ３ ) (Y=W / d) was calculated using the following formula: Porosity (%)=[1-(Y / X)]×100

[0107] [Evaluation of Mechanical Properties] As indicators of the mechanical properties of the porous substrate and the anion conductive membrane, the tensile strength and elongation at break were measured as follows. The tensile strength and elongation at break were measured at 25°C using an MX-500N electric measuring stand and a ZTA series force gauge (both trade names, manufactured by Imada Co., Ltd.). Each of the porous substrates used above and each of the anion conductive membranes obtained above were cut into 5 mm x 15 mm strips to obtain test pieces. Two parallel benchmark lines were marked at the center of the obtained test piece at 5 mm intervals, and both ends of the test piece were clamped and pulled at a speed of 0.5 mm / min. The maximum tensile stress at this time was defined as the tensile strength. The elongation at break was calculated using the following formula. The tensile strength and elongation at break were measured in this way. Elongation at break (%) = 100 x L / L ０ L ０ : distance between the gauge lines before the test, L: distance between the gauge lines at the time of fracture For the porous substrate of Example 11, 15 sheets of the porous substrate used to obtain the anion conductive membrane m11 were stacked, and the above measurement was performed. For the porous substrate of Comparative Example 2, two sheets of the porous substrate used to obtain the anion conductive membrane cm2 were stacked, and the above measurement was performed.

[0108] [Evaluation of Water Electrolysis Cells] A 1.5 M KOH aqueous solution heated to 70°C was supplied to the cathode catalyst layer and the anode catalyst layer of each of the water electrolysis cells obtained above at a flow rate of 10 mL / min. ２ The water electrolysis cells after initial energization were used to carry out the various evaluations described below.

[0109] <Resistance Evaluation: 1 A Overvoltage> The resistance of the anion conductive membrane was evaluated using the overvoltage as an index. ２ The initial voltage (V0) of each water electrolysis cell immediately after the initial energization (energization for 4 hours at 1 A / cm) was measured, and a 1.5 M KOH aqueous solution heated to 70°C was supplied to each water electrolysis cell after the initial energization. ２The voltage (V1) immediately after applying current for 10 minutes was measured. From the measured values, V1 - V0 was calculated as the overvoltage. The obtained overvoltage was applied to the following evaluation criteria to evaluate the resistance. The higher the overvoltage, the higher the resistance. - Evaluation criteria for overvoltage - A: More than 0.00V and 0.25V or less B: More than 0.25V and 0.30V or less C: More than 0.30V and 0.40V or less D: More than 0.40V and 0.50V or less E: More than 0.50V

[0110] <Evaluation of Hydrogen Gas Permeability> After the initial energization, a 1.5 M KOH aqueous solution heated to 70°C was supplied to each water electrolysis cell, and a current of 0.2 A / cm ２ A current was applied for 10 minutes at 50°C, and the gas recovered from the flow path of the bipolar plate on the anode side was analyzed to evaluate the extent to which hydrogen generated on the cathode side permeated to the anode side. Specifically, the gas recovered from the flow path of the bipolar plate on the anode side during the 10-minute current application was cooled to 0°C, and after removing water vapor, the gas was passed through a gas chromatograph (GC3210G, manufactured by GL Sciences, column: MS13X (trade name)), and the ratio of hydrogen gas contained in the recovered gas was evaluated according to the following evaluation criteria. - Evaluation criteria for hydrogen gas permeability (hydrogen gas ratio) - A: Less than 0.200 vol% B: 0.200 vol% or more and less than 1.200 vol% C: 1.200 vol% or more and less than 2.000 vol% D: 2.000 vol% or more and less than 3.500 vol% E: 3.500 vol% or more

[0111] <Evaluation of durability against high-temperature continuous current application> After the initial current application, each water electrolysis cell was subjected to a current application test at 0.5 A / cm while supplying a 1.5 M KOH aqueous solution heated to 80°C. ２ After applying current for 1000 hours, the ２ The current was applied for 1 hour at 0.5 A / cm ２ The voltage was applied for 10 minutes at 0.5 A / cm. ２The voltage V2 after applying current for 10 minutes was measured. The obtained voltage V2 was evaluated according to the following evaluation criteria. -Evaluation criteria for high temperature continuous current durability- A: More than 0.00 V and not more than 0.05 V B: More than 0.05 V and not more than 0.10 V C: More than 0.10 V and not more than 0.20 V D: More than 0.20 V and not more than 0.40 V E: More than 0.40 V

[0112]

[0113] "-": Indicates that the component was not used. "Ratio" for Monomer 1 and Monomer 2: Indicates the proportion (mol%) of each monomer in the total polymerizable monomers contained in the polymerizable monomer-containing solution. Polymerization method: When the monomer was polymerized by UV exposure, it was marked "UV," and when it was polymerized by heating, it was marked "thermal." When both UV exposure and heating were performed, it was marked "UV + thermal." Heteroelement ratio: [Total concentration of oxygen, sulfur, and nitrogen elements (at%)] / [Carbon concentration (at%)] Porous substrate components: When a polyethylene porous membrane was used, it was marked "PE." In addition, when multiple polyethylene porous membranes were used, the number used was listed next to "PE." For example, when two polyethylene porous membranes were used, it was marked "2 PE membranes." Porous substrate thickness: When multiple porous substrates were used, the total thickness was recorded. Polymer area ratio of anion conductive membrane: The area ratio of the anion conductive polymer on the surface having the larger area ratio of the anion conductive polymer to the surface area of ​​the two surfaces of the porous substrate is shown.

[0114]

[0115] In the anion conductive membrane of Comparative Example 1, the anion conductive polymer was disposed over 65% of one surface area in addition to within the pores of the porous substrate. The water electrolysis cell using this anion conductive membrane exhibited a voltage exceeding 0.20 V during continuous high-temperature current application. It is believed that the anion conductive membrane deteriorated or was damaged during continuous high-temperature current application. In the anion conductive membrane of Comparative Example 2, the anion conductive polymer was disposed over 60% of one surface area in addition to within the pores of the porous substrate. The water electrolysis cell using this anion conductive membrane exhibited poor results in all of 1 A overvoltage, gas permeability, and high-temperature continuous current application. In contrast, the anion conductive membranes of Examples 1 to 13 of the present invention exhibited the anion conductive polymer disposed over 70% or more of one surface area in addition to within the porous pores. The water electrolysis cell using this anion conductive membrane exhibited excellent results in all of 1 A overvoltage, gas diffusivity, and high-temperature continuous current application.

[0116] This application claims priority based on Japanese Patent Application No. 2024-135112, filed on August 13, 2024, the contents of which are incorporated herein by reference as part of the present specification.

[0117] REFERENCE SIGNS LIST 1 anion conductive membrane 2a anode catalyst layer 21 anode catalyst 23 ionomer resin 2c cathode catalyst layer 22 cathode catalyst 23 ionomer resin 3 gas diffusion layer 4 membrane electrode assembly 5 bipolar plate 10 water electrolysis cell

Claims

1. An anion conductive membrane comprising a porous substrate and an anion conductive polymer disposed within the pores of the porous substrate and on at least one surface of the porous substrate, covering 70% or more of the surface area, wherein the anion conductive polymer contains a component (I) derived from a polyfunctional polymerizable monomer having a total of two or more atoms of at least one of oxygen atoms, sulfur atoms, and nitrogen atoms in a structural portion other than a polymerizable group, and the proportion of the component (I) in the total components of the anion conductive polymer is 50 mol % or more.

2. The anion conducting membrane according to claim 1, which has a water retention capacity of 5% by mass or more.

3. The anion conductive membrane according to claim 2, wherein the elemental composition of the anion conductive polymer satisfies the following formula (a): [Total concentration (at %) of oxygen, sulfur, and nitrogen elements] / [Concentration (at %) of carbon element]≧0.05 4. The anion conducting membrane according to claim 3, wherein the component (I) has any one of the following structural units (i) to (viii): n is an integer of 1 or more. L represents a single bond, an alkylene group, or an arylene group. * represents a linking site.

5. The anion conducting membrane according to claim 4, wherein the component (I) is a nonionic component.

6. The anion conducting membrane according to claim 5, which has a thickness of 5 to 250 μm.

7. The anion conducting membrane according to claim 6, which has a tensile strength of 10 MPa or more and a breaking elongation of 100% or more.

8. The anion conducting membrane according to claim 7, which has an air permeability of 1000 seconds or more.

9. The anion conducting membrane according to claim 8, wherein the porosity of the porous substrate is 40 to 80%.

10. The anion conducting membrane according to claim 9, wherein the porous substrate has a tensile strength of 10 MPa or more and a breaking elongation of 100% or more.

11. The anion conducting membrane according to claim 10, wherein the material of the porous substrate comprises a hydrocarbon polymer.

12. A method for producing the anion conductive membrane according to any one of claims 1 to 10, comprising: impregnating a porous substrate with a polymerizable monomer-containing liquid containing 50 mol % or more of polyfunctional polymerizable monomers, each polyfunctional polymerizable monomer having a total of two or more atoms of at least one of oxygen, sulfur, and nitrogen atoms in structural moieties other than polymerizable groups, among all polymerizable monomers; subsequently polymerizing the polymerizable monomers; further placing a masking material having at least one opening on one surface of the porous substrate after the polymerization reaction; applying the polymerizable monomer-containing liquid to the masking material; subsequently polymerizing the polymerizable monomers applied to the masking material; and removing the masking material, thereby disposing an anion conductive polymer containing component (I) derived from the polyfunctional polymerizable monomer in the pores of the porous substrate and covering 70% or more of the surface area.

13. The method for producing an anion conducting membrane according to claim 12, wherein the polymerizable monomer-containing liquid has a solid content of 30% by mass or more.

14. A membrane electrode assembly having a structure in which a cathode catalyst layer, the anion conductive membrane according to any one of claims 1 to 11, and an anode catalyst layer are laminated in this order.

15. A method for producing hydrogen using the membrane electrode assembly according to claim 14.

16. A hydrogen production system comprising the membrane electrode assembly according to claim 14.

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