Solid polymer electrolyte membrane with catalyst layer, membrane electrode assembly, water electrolyzer, and hydrogen production method

Abstract

Provided is a solid polymer electrolyte membrane with a catalyst layer having low hydrogen permeability.　The solid polymer electrolyte membrane with a catalyst layer includes a first catalyst layer and a solid polymer electrolyte film. The first catalyst layer includes a fluorine-containing polymer F1-1 including a unit having a cyclic ether structure and a unit having an ion exchange group. The solid polymer electrolyte membrane includes a fluorine-containing polymer F2 including a unit having two or more ion exchange groups. The ion exchange capacity of the fluorine-containing polymer F2 is 1.65 meq / g dry resin or less.

Description

Solid polymer electrolyte membrane with catalyst layer, membrane electrode assembly, water electrolysis apparatus, and hydrogen production method. 【0001】 This disclosure relates to a solid polymer electrolyte membrane with a catalyst layer. Furthermore, this disclosure also relates to a membrane electrode assembly including the solid polymer electrolyte membrane with the catalyst layer, a water electrolysis apparatus including the membrane electrode assembly, and a method for producing hydrogen using the water electrolysis apparatus. 【0002】 Solid polymer water electrolyzers (hereinafter also referred to as "PEM water electrolyzers") are being utilized because they convert surplus electricity into gas for storage and use. For example, Patent Document 1 discloses a PEM water electrolyzer using a catalyst layer containing a fluorine-containing polymer. 【0003】 Japanese Patent Publication No. 2023-041182 【0004】 In PEM water electrolysis devices, low hydrogen permeability is required for the catalyst-layered solid polymer electrolyte membrane used in the membrane electrode assembly of the PEM water electrolysis device, in order to improve the efficiency of gas recovery. Hydrogen permeability refers to the degree to which hydrogen gas generated on the cathode side permeates to the anode side when water electrolysis is performed using a PEM water electrolysis device. 【0005】 The present inventors, referring to the material described in Patent Document 1, fabricated a catalyst layer for the anode or cathode and a solid polymer electrolyte membrane and applied them to a PEM water electrolysis apparatus, and found that there is room for further improvement in reducing hydrogen permeability. 【0006】 Therefore, one embodiment of the present invention aims to provide a solid polymer electrolyte membrane with a catalyst layer that has low hydrogen permeability. Another embodiment of the present invention also aims to provide a membrane electrode assembly, a water electrolysis device, and a method for producing hydrogen. 【0007】The disclosure includes the following embodiments: [1] A solid polymer electrolyte membrane with a catalyst layer, the first catalyst layer comprising a fluorine-containing polymer F1-1 comprising a unit having a cyclic ether structure and a unit having an ion exchange group, the solid polymer electrolyte membrane comprising a fluorine-containing polymer F2 comprising a unit having two or more ion exchange groups, and the ion exchange capacity of the fluorine-containing polymer F2 being 1.65 milliequivalents / g dry resin or less. [2] The solid polymer electrolyte membrane according to [1], wherein the unit having two or more ion exchange groups comprises a unit represented by formula (A-2). R Ｆ１ and R Ｆ２ Each of these independently comprises a perfluoroalkylene group having 1 to 3 carbon atoms, or a perfluoroalkylene group with -CF ２ - is a divalent group substituted with an etheric oxygen atom. Ｆ３ This is a perfluoroalkylene group having 1 to 6 carbon atoms. ＋ H ＋ , a monovalent metal cation or an ammonium ion in which one or more hydrogen atoms may be substituted with a hydrocarbon group. 2 M ＋These may be the same or different from each other. m is 0 or 1. [3] A solid polymer electrolyte membrane with a catalyst layer according to [1] or [2], wherein the ion exchange capacity of the fluorine-containing polymer F2 is 1.00 to 1.40 milliequivalents / g dry resin. [4] A solid polymer electrolyte membrane with a catalyst layer according to any one of [1] to [3], wherein the film thickness of the solid polymer electrolyte membrane is 25 to 150 μm. [5] A solid polymer electrolyte membrane with a catalyst layer according to any one of [1] to [4], wherein the number of ion exchange groups in the unit having the ion exchange group contained in the fluorine-containing polymer F1-1 is 2 or more. [6] A solid polymer electrolyte membrane with a catalyst layer according to any one of [1] to [5], wherein the ion exchange capacity of the fluorine-containing polymer F1-1 is 0.85 to 1.05 milliequivalents / g dry resin. [7] A solid polymer electrolyte membrane with a catalyst layer according to any one of [1] to [6], wherein the fluorine-containing polymer F1-1 and fluorine-containing polymer F2 further comprise units based on fluorine-containing olefins. [8] A solid polymer electrolyte membrane with a catalyst layer according to [7], wherein the fluorine-containing olefin is tetrafluoroethylene. [9] A solid polymer electrolyte membrane with a catalyst layer according to any one of [1] to [8], further comprising a second catalyst layer on the side of the solid polymer electrolyte membrane opposite to the first catalyst layer.

[10] A solid polymer electrolyte membrane with a catalyst layer according to [9], wherein the first catalyst layer comprises a platinum-containing catalyst, and the second catalyst layer comprises an iridium-containing catalyst.

[11] A solid polymer electrolyte membrane with a catalyst layer according to [9] or

[10] , wherein the second catalyst layer comprises a fluorine-containing polymer F1-2, and the fluorine-containing polymer F1-2 comprises units having ion exchange groups and units having a cyclic ether structure.

[12] A membrane electrode assembly comprising a solid polymer electrolyte membrane with a catalyst layer as described in any one of [1] to

[11] .

[13] A water electrolysis apparatus comprising the membrane electrode assembly described in

[12] .

[14] A method for producing hydrogen, comprising producing hydrogen by electrolyzing water using the water electrolysis apparatus described in

[13] . 【0008】 One embodiment of the present invention provides a solid polymer electrolyte membrane with a catalyst layer that has low hydrogen permeability. Another embodiment of the present invention also provides a membrane electrode assembly and a water electrolysis device. 【0009】 It is a schematic cross-sectional view showing an example of the membrane electrode assembly of the present disclosure. 【0010】 The following definitions of terms apply throughout this specification and the claims, unless otherwise specified. A numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of other stepwise numerical ranges. Also, in the numerical ranges described in this specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples. The "ion exchange group" is a group capable of exchanging at least a part of the ions contained in this group with other ions, and examples thereof include a sulfonic acid type functional group and a carboxylic acid type functional group. The "sulfonic acid type functional group" is the general name of an acid type sulfonic acid group (-SO ３ H), and a salt type sulfonic acid group (-SO ３ M. However, M is an alkali metal or a quaternary ammonium cation.). Here, as the form of the sulfonate group, for example, (-SO ３ － )Ma ＋ , (-SO ３ － ) ２ Mb ２＋ , and (-SO ３ － ) ３ Mc ３＋ are included (however, Ma ＋ is an alkali metal ion or a quaternary ammonium cation, Mb ２＋ is a divalent metal ion, and Mc ３＋ is a trivalent metal ion.). When there are two ligands, the number of ion exchange groups is counted as 2, and when there are three ligands, the number of ion exchange groups is counted as 3. The "carboxylic acid type functional group" is the general name of an acid type carboxylic acid group (-COOH), and a salt type carboxylic acid group (-COOM. However, M is an alkali metal or a quaternary ammonium cation.). Here, as the form of the carboxylate group, for example, (-COO－ ) Ma ＋ , (-COO － ) ２ Mb ２＋ , and, (-COO － ) ３ Mc ３＋ (However, Ma ＋ is an alkali metal ion or a quaternary ammonium cation, and Mb ２＋ It is a divalent metal ion, Mc ３＋ is a trivalent metal ion. Note that when there are two ligands, the number of ion exchange groups is counted as two, and when there are three ligands, the number of ion exchange groups is counted as three. "Groups that can be converted to ion exchange groups" refers to groups that can be converted to ion exchange groups by treatments such as hydrolysis and acidification, and is sometimes referred to as "precursor groups." "Groups that can be converted to sulfonic acid-type functional groups" refers to groups that can be converted to sulfonic acid-type functional groups by treatments such as hydrolysis and acidification. "Groups that can be converted to carboxylic acid-type functional groups" refers to groups that can be converted to carboxylic acid-type functional groups by known treatments such as hydrolysis and acidification. 【0011】 In polymers, a "unit" refers to an atomic group derived from a single monomer molecule, formed by the polymerization of monomers. A unit may be an atomic group directly formed by the polymerization reaction, or it may be an atomic group in which a portion of the polymer obtained by the polymerization reaction is converted to a different structure by processing. Note that constituent units derived from individual monomers may be described by adding "unit" to the monomer name. A unit represented by formula (u11) is denoted as unit (u11). Other units represented by formulas are described similarly. 【0012】[Solid polymer electrolyte membrane with catalyst layer] The solid polymer electrolyte membrane with a catalyst layer of the present disclosure is a solid polymer electrolyte membrane with a catalyst layer having a first catalyst layer and a solid polymer electrolyte membrane, wherein the first catalyst layer contains a fluorine-containing polymer F1-1 containing a unit having a cyclic ether structure (hereinafter also referred to as "unit A") and a unit having an ion exchange group, the solid polymer electrolyte membrane contains a fluorine-containing polymer F2 containing a unit having two or more ion exchange groups, and the ion exchange capacity of the fluorine-containing polymer F2 is 1.65 milliequivalents / g dry resin or less. 【0013】 The mechanism by which hydrogen permeability is reduced in the catalyst-layered solid polymer electrolyte membrane of this disclosure is not entirely clear, but the inventors speculate as follows: In the catalyst-layered solid polymer electrolyte membrane of this disclosure, the fluorine-containing polymer F1-1 contained in the first catalyst layer has a cyclic ether structure, so gases (e.g., oxygen gas or hydrogen gas) generated in the catalyst layer are easily discharged quickly before they can move to the solid polymer electrolyte membrane side. Furthermore, the solid polymer electrolyte membrane in the catalyst-layered solid polymer electrolyte membrane of this disclosure contains a fluorine-containing polymer F2 containing units of a predetermined structure, and its ion exchange capacity is within a predetermined range, so gas permeability tends to be low. By using the above-mentioned solid polymer electrolyte membrane and the first catalyst layer simultaneously, the above effects act synergistically, and it is thought that hydrogen permeability is reduced in the catalyst-layered solid polymer electrolyte membrane of this disclosure. 【0014】 The catalyst layer-equipped solid polymer electrolyte membrane (hereinafter also simply referred to as "CCM") of this disclosure will be described below. 【0015】 <First Catalyst Layer> The first catalyst layer of the CCM contains a fluorine-containing polymer F1-1 which includes units having a cyclic ether structure (unit A) and units having an ion exchange group. The first catalyst layer may also contain a catalyst. The fluorine-containing polymer F1-1 and catalyst contained in the first catalyst layer, as well as the properties of the first catalyst layer, will be described below. 【0016】(Fluorine-containing polymer F1-1) The fluorine-containing polymer F1-1 contained in the first catalyst layer has unit A. The cyclic ether structure in unit A is preferably a cyclic ether structure having a five-membered ring or a cyclic ether structure having a six-membered ring. The cyclic ether structure having a five-membered ring and the cyclic ether structure having a six-membered ring preferably have one or two etheric oxygen atoms. More specifically, the unit having a cyclic ether structure is preferably at least one unit selected from the group consisting of the following units (u11), (u12), (u21), (u22), and (u24). 【0017】 【0018】 R １１ This is a divalent perfluoroalkylene group which may have ether-bonded oxygen atoms. When the perfluoroalkylene group has ether-bonded oxygen atoms, the number of oxygen atoms may be one or two or more. Furthermore, the ether-bonded oxygen atoms may be located between carbon-carbon bonds of the perfluoroalkylene group, or at the ends of carbon-carbon bonds. The perfluoroalkylene group may be linear or branched, with linear being preferred. １２ , R １３ , R １５ and R １６ Each of these is independently a monovalent perfluoroalkyl group or fluorine atom which may have an etheric oxygen atom. １５ and R １６ From the standpoint of high polymerization reactivity, it is preferable that at least one of the atoms is a fluorine atom, and more preferably that both atoms are fluorine atoms. １４ This may have an etheric oxygen atom, a monovalent perfluoroalkyl group, a fluorine atom, or -R １１ (SO ２ X (SO ２ R ｆ ) ａ ) － M ＋The group is represented by . When the perfluoroalkyl group has an etheric oxygen atom, the number of oxygen atoms may be one or two or more. The etheric oxygen atom may be located between the carbon-carbon bonds of the perfluoroalkyl group or at the end of the carbon atom bond. The perfluoroalkyl group may be linear or branched, with linear being preferred. In formula (u11), two R １１ If it includes two R １１ These may be identical or different from one another. ＋ H ＋ , a monovalent metal cation (e.g., potassium ion, sodium ion) or an ammonium ion in which one or more hydrogen atoms may be substituted with a hydrocarbon group (e.g., methyl group, ethyl group), and from the viewpoint of high conductivity, H ＋ M is preferable. ＋ If there are multiple, multiple M ＋ These may be identical or different from one another. ｆ This is a linear or branched perfluoroalkyl group which may have ether-bonded oxygen atoms. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 8, and more preferably 1 to 6. Two or more R ｆ If it has two or more R ｆ These elements may be the same or different from each other. X is an oxygen atom, a nitrogen atom, or a carbon atom, where a=0 if X is an oxygen atom, a=1 if X is a nitrogen atom, and a=2 if X is a carbon atom. - (SO ２ X (SO ２ R ｆ ) ａ ) － M ＋ A specific example of a group is the sulfonic acid group (-SO ３ － M ＋ (SO) sulfonimide group (-SO ２ N (SO ２ R ｆ ) － M ＋ (SO) and sulfonemethide group ((-SO) ２ C (SO ２ R ｆ ) ２) － M ＋ groups). 【0019】 As the unit (u11), the unit (u11-1) is preferable. 【0020】 【0021】 【0022】 R ２１ is a perfluoroalkylene group having 1 to 6 carbon atoms or a perfluoroalkylene group having 2 to 6 carbon atoms and having an etheric oxygen atom between carbon-carbon bonds. When the perfluoroalkylene group has an etheric oxygen atom, the number of oxygen atoms may be 1 or 2 or more. The perfluoroalkylene group may be linear or branched, and a linear form is preferable. R ２２ is a fluorine atom, a perfluoroalkyl group having 1 to 6 carbon atoms, a perfluoroalkyl group having 2 to 6 carbon atoms and having an etheric oxygen atom between carbon-carbon bonds, or -R ２１ (SO ２ X(SO ２ R ｆ ) ａ ) － M ＋ represented by the group. When the perfluoroalkyl group has an etheric oxygen atom, the number of oxygen atoms may be 1 or 2 or more. The perfluoroalkyl group may be linear or branched, and a linear form is preferable. In formula (u12), when two Rs ２１ are included, the two Rs ２１ may be the same as or different from each other. M ＋ , R ｆ [[ID=4​​​​​​​​​​​​​​ 【0025】 【0026】 R ４１ 、R ４２ 、R ４３ 、R ４４ 、R ４５ and R ４６ are each independently a monovalent perfluoroalkyl group which may have an etheric oxygen atom or a fluorine atom. When the perfluoroalkyl group has an etheric oxygen atom, the number of oxygen atoms may be one or two or more. Further, the etheric oxygen atom may be located between carbon-carbon bonds of the perfluoroalkyl group or at the terminal of the carbon atom bond. The perfluoroalkyl group may be linear or branched, and a linear form is preferred. R ４５ and R ４６ are preferably such that at least one of them is a fluorine atom from the viewpoint of high polymerization reactivity, and more preferably both are fluorine atoms. 【0027】 As the unit (u21), the unit (u21-1) is preferred. 【0028】 【0029】 【0030】 s is 0 or 1, and 0 is preferred. R ５１ and R ５２ are each independently a fluorine atom, a perfluoroalkyl group having 1 to 5 carbon atoms or a spiro ring formed by being linked to each other (however, when s is 0). R ５３ and R ５４ are each independently a fluorine atom or a perfluoroalkyl group having 1 to 5 carbon atoms. R[[ID=4​​​​​The preferred unit is (u22-1). 【0032】 【0033】 【0034】 R ７１ ~R ７６ Each of these is independently a monovalent perfluoroalkyl group or a fluorine atom, which may have an etheric oxygen atom. If the perfluoroalkyl group has an etheric oxygen atom, the number of oxygen atoms may be one or two or more. Furthermore, the etheric oxygen atom may be inserted between carbon-carbon bonds of the perfluoroalkyl group, or it may be inserted at the carbon atom bond ends. The perfluoroalkyl group may be linear or branched, with linear being preferred. ７１ ~R ７４ It is preferable that the atom is a fluorine atom due to its high polymerization reactivity. 【0035】 Among the specified cyclic ether structural units described above, unit A preferably includes at least one unit selected from the group consisting of units (u21), (u22), and (u24), and more preferably is unit (u22), in order to obtain a catalyst layer with superior oxygen permeability. 【0036】The content of unit A is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 55 mol% or more, particularly preferably 60 mol% or more, and most preferably 62 mol% or more, relative to the total units contained in the fluorine-containing polymer F1-1. Furthermore, the content of unit A is preferably 87 mol% or less, more preferably 80 mol% or less, even more preferably 75 mol% or less, and particularly preferably 70 mol% or less, relative to the total units contained in the fluorine-containing polymer F1-1, from the viewpoint of further suppressing the occurrence of cracking in the catalyst layer. The content of unit A is preferably 30 to 87 mol%, more preferably 50 to 80 mol%, even more preferably 55 to 75 mol%, particularly preferably 60 to 70 mol%, and most preferably 62 to 70 mol%, relative to the total units contained in the fluorine-containing polymer F1-1. The fluorine-containing polymer F1-1 may contain only one type of unit A or two or more types. When two or more types are included, the above content refers to the total amount of these units. 【0037】 The fluorine-containing polymer F1-1 contains units having ion exchange groups (hereinafter also referred to as "unit B"). Unit B does not contain cyclic ether structures. The number of ion exchange groups in each unit contained in unit B is preferably one or more, more preferably two or more from the standpoint of easily obtaining a high molecular weight polymer while maintaining the content of unit A, and even more preferably two from the standpoint of facilitating monomer synthesis. 【0038】 As unit B, a perfluoromonomer unit having an ion exchange group is preferred, a perfluoromonomer unit having two or more ion exchange groups is more preferred, and a perfluoromonomer unit having two ion exchange groups is even more preferred. As the ion exchange group, a sulfonic acid type functional group is preferred. As unit B, a perfluoromonomer unit having two sulfonic acid type functional groups is preferred. As the perfluoromonomer unit, unit (u31), unit (A-1), unit (A-2), or unit (A-3) is preferred, and unit (u31) or unit (A-2) is more preferred. 【0039】 【0040】In formula (u31), Z is a fluorine atom or a trifluoromethyl group, q is 0 or 1, m is an integer from 0 to 3, p is 0 or 1, n is an integer from 1 to 12, and m + p > 0. In formula (u31), M ＋ H ＋ , a monovalent metal cation (e.g., potassium ion, sodium ion) or an ammonium ion in which one or more hydrogen atoms may be substituted with a hydrocarbon group (e.g., methyl group, ethyl group), H ＋ It is preferable. 【0041】 【0042】 In formulas (A-1) to (A-3), R Ｆ１ and R Ｆ２ Each of these independently comprises a perfluoroalkylene group having 1 to 3 carbon atoms, or a perfluoroalkylene group with -CF ２ - is a divalent group substituted with an etheric oxygen atom. In the above divalent group, the etheric oxygen atom may be located at the terminal end of the perfluoroalkylene group or between carbon atoms. The number of carbon atoms in the above divalent group is preferably 1 to 3, and more preferably 2 or 3. Ｆ１ and R Ｆ２ A specific example is -CF ２ -, -CF ２ CF ２ -, -CF (CF ３ ) -, -CF ２ CF ２ CF ２ -, -CF (CF ２ CF ３ )-,-CF(CF ３ ) CF ２ -, -CF ２ CF (CF ３ )-,-C(CF ３ ) (CF ３ ) -, -CF ２ OCF ２ CF ２ -, and -OCF ２ CF ２ - is one of the advantages. The raw materials are inexpensive, the manufacturing process is easy, and the ion exchange capacity of the fluorine-containing polymer F1-1 can be increased.Ｆ１ and R Ｆ２ These are, independently, a perfluoroalkylene group having 1 or 2 carbon atoms, -CF ２ OCF ２ CF ２ - or -OCF ２ CF ２ - is preferred. In the case of a perfluoroalkylene group having 2 carbon atoms, a linear structure is preferred. Specifically, -CF ２ -, -CF ２ CF ２ - or - CF (CF ３ ) - Preferably, -CF ２ - or -CF ２ CF ２ - is more preferable, -CF ２ - is even more preferable. 【0043】 In formulas (A-1) to (A-3), M ＋ H ＋ , a monovalent metal cation (e.g., potassium ion, sodium ion) or an ammonium ion in which one or more hydrogen atoms may be substituted with a hydrocarbon group (e.g., methyl group, ethyl group), H ＋ It is preferable. 【0044】 In formula (A-2), R Ｆ３ This is a perfluoroalkylene group having 1 to 6 carbon atoms. Ｆ３ A specific example is -CF ２ -, -CF ２ CF ２ -, -CF (CF ３ ) -, -CF ２ CF ２ CF ２ -, -CF (CF ２ CF ３ )-,-CF(CF ３ ) CF ２ -, -CF ２ CF (CF ３ )-,-C(CF ３ ) (CF ３ ) - and -CF ２ CF (CF ３ ) OCF ２ CF (CF ３)-- is one example. R Ｆ３ As such, a perfluoroalkylene group having 1 to 3 carbon atoms is preferred. Specifically, -CF ２ -, -CF ２ CF ２ - or -CF ２ CF (CF ３ ) - Preferably, -CF ２ - or -CF ２ CF (CF ３ ) - is more preferable. In formula (A-2), m is 0 or 1. 【0045】 The content of unit B is preferably 10 mol% or more, and more preferably 13 mol% or more, relative to the total units contained in the fluorine-containing polymer F1-1, from the viewpoint of good proton conductivity. The content of unit B is preferably 50 mol% or less, more preferably 30 mol% or less, even more preferably 20 mol% or less, and particularly preferably 14 mol% or less, relative to the total units contained in the fluorine-containing polymer F1-1, from the viewpoint of improved water repellency, increased drainage, and improved power generation efficiency. The content of unit B is preferably 10 to 50 mol%, more preferably 10 to 30 mol%, even more preferably 10 to 20 mol%, and particularly preferably 13 to 20 mol% or 10 to 14 mol% relative to the total units contained in the fluorine-containing polymer F1-1. The fluorine-containing polymer F1-1 may contain only one type of unit B or two or more types. When two or more types are included, the above content refers to the total amount of these units. 【0046】The fluorine-containing polymer F1-1 preferably further contains units based on fluorine-containing olefins (hereinafter also referred to as "unit C"). Examples of fluorine-containing olefins include fluoroolefins having 2 to 3 carbon atoms and containing one or more fluorine atoms in the molecule. Specific examples of fluoroolefins include tetrafluoroethylene (hereinafter also referred to as "TFE"), chlorotrifluoroethylene, vinylidene fluoride, vinyl fluoride, and hexafluoropropylene, with TFE being preferred. One type of fluorine-containing olefin may be used alone, or two or more types may be used in combination. The presence of unit C can impart water repellency. The content of unit C is preferably 5 mol% or more relative to the total units contained in the fluorine-containing polymer F1-1. The content of unit C is preferably 35 mol% or less relative to the total units contained in the fluorine-containing polymer F1-1. The content of unit C is preferably 5 to 35 mol% relative to the total units contained in the fluorine-containing polymer F1-1. 【0047】 The total content of units A, B, and C is preferably 90 mol% or more, and more preferably 99 mol% or more, relative to the total units contained in the fluorine-containing polymer F1-1. The total content of units A, B, and C is preferably 100 mol% or less. 【0048】 The fluorine-containing polymer F1-1 may contain units based on monomers having two or more polymerizable unsaturated bonds (hereinafter also referred to as "unit D"). In this specification, units based on monomers that include a cyclic ether structure and have two or more polymerizable unsaturated bonds are treated as unit D. Specific examples of polymerizable unsaturated bonds include carbon-carbon double bonds (C=C) and carbon-carbon triple bonds (C≡C). The number of polymerizable unsaturated bonds in monomers having two or more polymerizable unsaturated bonds is preferably 2 to 6, more preferably 2 or 3, and even more preferably 2, from the viewpoint of superior polymerization reactivity. Among monomers having two or more polymerizable unsaturated bonds, monomers having a fluorine atom are preferred, and perfluoromonomers are more preferred. 【0049】Unit D is preferably the unit represented by formula (u41) because it can further suppress the occurrence of cracking in the catalyst layer. The unit represented by formula (u41) may be in a form that crosslinks two polymer chains, or it may be incorporated into the same polymer chain. 【0050】 【0051】 In formula (u41), Q ４ This is a divalent perfluoroalkylene group which may have an oxygen atom or an ether-bonded oxygen atom. Q ４ If the perfluoroalkylene group has an etheric oxygen atom, the number of oxygen atoms may be one or two or more. The etheric oxygen atom may be located between carbon-carbon bonds of the perfluoroalkylene group or at the end of the carbon-carbon bond. The perfluoroalkylene group may be linear or branched, and is preferably linear. The number of carbon atoms in the perfluoroalkylene group is preferably 1 to 10, more preferably 2 to 8, and even more preferably 3 or 4. 【0052】 Specific examples of unit D include unit (u41-1), unit (u41-2), and unit (u41-3), with unit (u41-2) being preferred because it can further suppress the occurrence of cracks in the catalyst layer. 【0053】 【0054】 In the above unit, m1 and m3 are each independently integers from 2 to 8, with 3 or 4 being preferred. In the above unit, m2 and m4 are each independently integers from 0 to 5, and m2 + m4 ≥ 1. 【0055】The content of unit D is preferably 0.001 mol% or more, more preferably 0.005 mol% or more, and even more preferably 0.01 mol% or more, relative to the total units contained in the fluorine-containing polymer F1-1, from the viewpoint of further suppressing the occurrence of cracking in the catalyst layer. The content of unit D is preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 1 mol% or less, and particularly preferably 0.2 mol% or less, relative to the total units contained in the fluorine-containing polymer F1-1, from the viewpoint of superior power generation characteristics. The fluorine-containing polymer F1-1 may contain only one type of unit D or two or more types. When two or more types are included, the above content refers to the total amount of these units. 【0056】 The fluorine-containing polymer F1-1 may contain units other than those mentioned above (hereinafter also referred to as "other units"). Specific examples of other units include monomer-based units such as perfluoro(3-butenyl vinyl ether), perfluoro(allyl vinyl ether), perfluoroα-olefins (such as hexafluoropropylene), and perfluoro(alkyl vinyl ethers). 【0057】 The softening temperature of the fluorine-containing polymer F1-1 is preferably 135°C or higher, more preferably 150°C or higher, and even more preferably 160°C or higher. The softening temperature of the fluorine-containing polymer F1-1 is preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower, from the viewpoint of further suppressing cracking of the catalyst layer. The softening temperature of the fluorine-containing polymer F1-1 is determined by the method described in the Examples section below. 【0058】From the viewpoint of ionic conductivity, the ion exchange capacity of the fluorine-containing polymer F1-1 is preferably 0.80 milliequivalents / g dry resin or higher, more preferably 0.85 milliequivalents / g dry resin or higher, and even more preferably 0.90 milliequivalents / g dry resin or higher. From the viewpoint of the electrolytic voltage being lower, the ion exchange capacity of the fluorine-containing polymer F1-1 is preferably 1.60 milliequivalents / g dry resin or lower, more preferably 1.50 milliequivalents / g dry resin or lower, even more preferably 1.20 milliequivalents / g dry resin or lower, particularly preferably 1.10 milliequivalents / g dry resin or lower, and most preferably 1.05 milliequivalents / g dry resin or lower. The ion exchange capacity of the fluorine-containing polymer F1-1 is preferably 0.80 to 1.60 milliequivalents / g dry resin, more preferably 0.80 to 1.50 milliequivalents / g dry resin, even more preferably 0.80 to 1.20 milliequivalents / g dry resin, even more preferably 0.80 to 1.10 milliequivalents / g dry resin, particularly preferably 0.80 to 1.05 milliequivalents / g dry resin, and most preferably 0.85 to 1.05 milliequivalents / g dry resin. The method for measuring the ion exchange capacity of the fluorine-containing polymer F1-1 is as described in the examples section below. 【0059】 When the catalyst layer in the anode contains a fluorine-containing polymer F1-1, the total content of the fluorine-containing polymer F1-1 and the catalyst is preferably 90% by mass or more, and more preferably 99% by mass or more, relative to the total mass of the catalyst layer in the anode. Furthermore, the upper limit of the above total content is preferably 100% by mass. When the catalyst layer in the cathode contains a fluorine-containing polymer F1-1, the total content of the fluorine-containing polymer F1-1 and the catalyst is preferably 90% by mass or more, and more preferably 99% by mass or more, relative to the total mass of the catalyst layer in the cathode. Furthermore, the upper limit of the above total content is preferably 100% by mass. 【0060】 The method for producing fluorine-containing polymer F1-1 will be explained using the case where fluorine-containing polymer F1-1 has acidic sulfonic acid groups as an example. One example of a method for producing fluorine-containing polymer F1-1 is to use the acidic sulfonic acid groups in fluorine-containing polymer F1-1 as precursor groups (specifically, -SO ２The precursor group of the precursor polymer (hereinafter also referred to as "polymer F"), which is a group represented by F, is an acidic sulfonic acid group (-SO ３ － H ＋ One method is to convert it to the precursor group -SO ２ A specific example of a method for converting the group represented by F to an acidic sulfonic acid group is the -SO group of polymer F. ２ One method involves hydrolyzing the group represented by F to obtain a salt-type sulfonic acid group, and then converting the salt-type sulfonic acid group to an acid-type sulfonic acid group. 【0061】 The TQ value of polymer F is preferably 300°C or lower, and more preferably 290°C or lower. A TQ value of 300°C or lower improves the solubility or dispersibility of the fluorine-containing polymer F1-1 in the liquid medium, making it easier to prepare the catalyst ink. The TQ value of polymer F is preferably 100°C or higher, more preferably 130°C or higher, and even more preferably 160°C or higher. A TQ value of 100°C or higher yields a fluorine-containing polymer F1-1 with sufficient molecular weight, resulting in excellent catalyst layer strength. The TQ value is related to the molecular weight of the polymer, and the volumetric flow rate is 100 mm. ３ This is expressed in terms of temperature per second. The volumetric flow rate is measured by melting and flowing a polymer through a constant-temperature nozzle (inner diameter: 1 mm, length: 1 mm) under a pressure of approximately 3 MPa, and measuring the amount of polymer flowing out in mm³. ３ This is expressed in units of per second. The TQ value is an indicator of the molecular weight of the polymer; a higher TQ value indicates a higher molecular weight. The TQ value of polymer F is determined by the method described in the Examples section below. 【0062】(Catalyst) The first catalyst layer may contain a catalyst. When the first catalyst layer is used as the anode-side catalyst layer, it is preferable that it contains an iridium-containing catalyst (a catalyst containing iridium). Examples of iridium-containing catalysts include iridium oxide catalysts, composite oxide catalysts containing iridium and other metal elements, alloy catalysts containing iridium oxide, and iridium oxide-containing catalysts having a core-shell structure. Examples of the other metals include ruthenium, titanium, zirconium, hafnium, niobium, tantalum, molybdenum, tungsten, platinum, and gold. The catalyst may also be supported on an insoluble support. Examples of insoluble supports include known metal oxide supports. 【0063】 The iridium-containing catalyst is preferably in particulate form. 【0064】 When the first catalyst layer contains a fluorine-containing polymer F1-1 and an iridium-containing catalyst, the mass ratio of the content of the fluorine-containing polymer F1-1 to the content of iridium (content of fluorine-containing polymer F1-1 / iridium content, hereinafter also referred to as "I / Ir") is preferably 0.05 or higher, and more preferably 0.10 or higher. I / Ir is preferably 0.40 or lower, and more preferably 0.30 or lower. 【0065】When the first catalyst layer is used as the cathode-side catalyst layer, it is preferable that it contains a platinum-containing catalyst (a catalyst containing platinum), more preferably a carbon support and a platinum-containing catalyst, and even more preferably a supported catalyst in which a platinum-containing catalyst is supported on a carbon support. Examples of platinum-containing catalysts include elemental platinum, platinum alloys, and platinum alloys having a core-shell structure. Other metallic elements other than platinum that can be included in platinum alloys include platinum group metals other than platinum (e.g., ruthenium, rhodium, palladium, osmium, and iridium), gold, silver, chromium, iron, titanium, manganese, cobalt, nickel, molybdenum, tungsten, aluminum, silicon, zinc, and tin. Examples of carbon supports include solid carbon supports and hollow carbon supports. The carbon support may also have pores of varying sizes (e.g., macropores, mesopores, and micropores). Examples of carbon supports include Ketjenblack, acetylene black, graphitized carbon, mesoporous carbon, carbon fiber, and carbon nanotubes. When the first catalyst layer is used as the cathode-side catalyst layer, the first catalyst layer may contain a catalyst that does not contain platinum group metals. Examples of catalysts that do not contain platinum group metals include metal oxide catalysts, metal oxynitride catalysts, and carbon alloy catalysts. 【0066】 The platinum-containing catalyst is preferably in particulate form. The average particle size (number-average particle size D50) of the platinum-containing catalyst is preferably 1.0 nm or more, and more preferably 2.0 nm or more. The above average particle size is preferably 10.0 nm or less, and more preferably 5.0 nm or less. The average particle size of the platinum-containing catalyst is measured, for example, by TEM (transmission electron microscope) and SAXS (small-angle X-ray scattering). The amount of platinum-containing catalyst supported in the supported catalyst is preferably 20.0% by mass or more, and more preferably 30.0% by mass or more, relative to the total mass of the catalyst. The above amount is preferably 70.0% by mass or less, and more preferably 60.0% by mass or less. 【0067】When the first catalyst layer contains a fluorine-containing polymer F1-1 and a platinum-containing catalyst, the mass ratio of the fluorine-containing polymer F1-1 content to the platinum content (fluorine-containing polymer F1-1 content / platinum content) is preferably 1.2 or higher, and more preferably 1.4 or higher. The above mass ratio is preferably 3.0 or lower. 【0068】 When the first catalyst layer contains a carbon support, the mass ratio of the fluorine-containing polymer F1-1 content to the carbon support content (fluorine-containing polymer F1-1 content / carbon support content, hereinafter also referred to as "I / C") is preferably 0.4 or higher, and more preferably 0.6 or higher, from the viewpoint of tackiness. I / C is preferably 1.5 or lower, and more preferably 1.2 or lower. Furthermore, from the viewpoint of improving material transportability with increasing voids in the cathode, the above mass ratio is preferably 0.2 to 1.5. 【0069】 If the first catalyst layer contains a carbon support, the specific surface area of ​​the carbon support is 60 m². ２ Preferably 100 m ２ More preferably 150m / g or more. ２ A value of 1 / g or more is even more preferable. Furthermore, the specific surface area is 1,500 m². ２ Preferably less than / g, and 1,200m ２ A value of less than / g is more preferable. 【0070】 (Other Components) The first catalyst layer may contain other components in addition to the various components described above. Examples of other components include hydrophobic particles, hydrophilic particles, dispersants, and fibrous carbon. Examples of hydrophobic particles include polytetrafluoroethylene particles. Examples of hydrophilic particles include metal oxide particles. 【0071】The first catalyst layer can be formed, for example, by applying a catalyst ink containing a catalyst, a liquid medium, and a fluorine-containing polymer F1-1 onto a substrate film to form a coating film, and then drying the coating film to remove the liquid medium from the coating film. The substrate film is preferably a release material (for example, an ethylene tetrafluoroethylene sheet). Examples of catalysts include catalysts that may be contained in the first catalyst layer described above. The liquid medium preferably contains at least one selected from the group consisting of water and alcohol, and more preferably contains both water and alcohol. Specific examples of alcohols include methanol, ethanol, propanol (e.g., 1-propanol, 2-propanol), 1-butanol, 2-methyl-1-propanol, 2-butanol, 2-methyl-2-propanol, 2,2,2-trifluoroethanol, 2,2,3,3,3-pentafluoro-1-propanol, 2,2,3,3-tetrafluoro-1-propanol, 4,4,5,5,5-pentafluoro-1-pentanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 3,3,3-trifluoro-1-propanol, 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexanol, and 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-1-octanol. The alcohol preferably contains propanol. Alcohol may be used alone or in combination of two or more types. 【0072】 The first catalyst layer may be formed by applying a catalyst ink to a solid polymer electrolyte membrane, a gas diffusion layer, or a carbon layer (as described later) to form a coating film, and then drying the coating film to remove the liquid medium from the coating film. Alternatively, the formed first catalyst layer may be subjected to further heat treatment. Examples of heat treatment methods include hot pressing. 【0073】(Properties, etc.) The thickness of the catalyst layer is preferably 0.1 μm or more, and more preferably 5 μm or more. The thickness of the catalyst layer is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 30 μm or less, and particularly preferably 15 μm or less. The thickness of the catalyst layer can be measured, for example, using an image obtained by measuring a cross-section cut in the thickness direction of the film electrode assembly with a laser microscope, and the arithmetic mean of any 20 locations can be used. 【0074】 <Solid Polymer Electrolyte Membrane> The solid polymer electrolyte membrane possessed by CCM contains a fluorine-containing polymer F2 that includes units having two or more ion exchange groups, and the ion exchange capacity of the above fluorine-containing polymer F2 is 1.65 milliequivalents / g dry resin or less. The fluorine-containing polymer F2 contained in the solid polymer electrolyte membrane and the solid polymer electrolyte membrane will be described below. 【0075】 (Fluorine-containing polymer F2) The solid polymer electrolyte membrane contains a fluorine-containing polymer F2. The fluorine-containing polymer F2 contains units having two or more ion-exchange groups. Specific examples of groups that can be converted to ion-exchange groups include groups that can be converted to sulfonic acid-type functional groups and groups that can be converted to carboxylic acid-type functional groups. From the viewpoint of suitability for water electrolysis, groups that can be converted to sulfonic acid-type functional groups are preferred. Furthermore, from the viewpoint of applicability to water electrolysis, it is also preferable that the unit does not contain carboxylic acid-type functional groups. The units having two or more ion-exchange groups are preferably units based on perfluorovinyl ether or perfluoroallyl ether, and from the viewpoint of superior effects in this disclosure, units based on perfluorovinyl ether are more preferred. 【0076】 The unit having two or more ion exchange groups preferably contains two or more sulfonic acid type functional groups and a fluorine atom, and the unit represented by formula (1) is more preferred. As the above monomer, the monomer represented by formula (1) is preferred. Formula (1) -[CF ２ -CF(-L-(SO ３ － M ＋ ) ２ )]- L is a trivalent perfluorohydrocarbon group which may contain an etheric oxygen atom. M＋ H ＋ , alkali metal cation or quaternary ammonium cation, H ＋ It is preferable that the etheric oxygen atom contained in the trivalent perfluorohydrocarbon group may be located at the terminal end of the perfluorohydrocarbon group or between carbon atoms. The number of carbon atoms in the trivalent perfluorohydrocarbon group is preferably 1 or more, particularly preferably 2 or more, preferably 20 or less, and particularly preferably 10 or less. As L, a trivalent perfluoroaliphatic hydrocarbon group which may contain an etheric oxygen atom is preferred. As unit (1), the above-mentioned unit (A-1), unit (A-2), or unit (A-3) is preferred, and unit (A-2) is more preferred. 【0077】 The content of units having two or more ion exchange groups is preferably 5 mol% or more, more preferably 7 mol% or more, and even more preferably 8 mol% or more, relative to the total units in the fluorine-containing polymer F2. The content of units having two or more ion exchange groups is preferably 14 mol% or less, more preferably 13 mol% or less, and even more preferably 12 mol% or less, relative to the total units in the fluorine-containing polymer F2. The content of units having two or more ion exchange groups is preferably 5 to 14 mol%, more preferably 7 to 13 mol%, and even more preferably 8 to 12 mol%, relative to the total units in the fluorine-containing polymer F2. 【0078】 The fluorine-containing polymer F2 preferably contains the above-mentioned unit C. The content of unit C is preferably 86 mol% or more, more preferably 87 mol% or more, and even more preferably 88 mol% or more, relative to the total units in the fluorine-containing polymer F2. The content of unit C is preferably 95 mol% or less, more preferably 93 mol% or less, and even more preferably 92 mol% or less, relative to the total units in the fluorine-containing polymer F2. The content of unit C is preferably 86 to 95 mol%, more preferably 87 to 93 mol%, and even more preferably 88 to 92 mol%, relative to the total units in the fluorine-containing polymer F2. 【0079】The fluorine-containing polymer F2 may contain the unit D described above. If the fluorine-containing polymer F2 contains the unit C described above and a unit having two or more ion-exchange groups, the total content of unit C and the unit having two or more ion-exchange groups is preferably 90 mol% or more, and more preferably 99 mol% or more, relative to the total units in the fluorine-containing polymer F2. An upper limit of 100 mol% is given. 【0080】 From the viewpoint of ionic conductivity, the ion exchange capacity of the fluorine-containing polymer F2 is preferably 0.90 milliequivalents / g dry resin or more, more preferably 1.00 milliequivalents / g dry resin or more, even more preferably 1.05 milliequivalents / g dry resin or more, and particularly preferably 1.10 milliequivalents / g dry resin or more. The ion exchange capacity of the fluorine-containing polymer F2 is 1.65 milliequivalents / g dry resin or less, preferably 1.55 milliequivalents / g dry resin or less, more preferably 1.45 milliequivalents / g dry resin or less, even more preferably 1.40 milliequivalents / g dry resin or less, particularly preferably 1.35 milliequivalents / g dry resin or less, and most preferably 1.30 milliequivalents / g dry resin or less. The ion exchange capacity of the fluorine-containing polymer F2 is 0.90 to 1.65 milliequivalents / g dry resin, preferably 0.90 to 1.55 milliequivalents / g dry resin, more preferably 1.00 to 1.45 milliequivalents / g dry resin, even more preferably 1.00 to 1.40 milliequivalents / g dry resin, particularly preferably 1.05 to 1.35 milliequivalents / g dry resin, and most preferably 1.10 to 1.30 milliequivalents / g dry resin. 【0081】 A method for producing fluorine-containing polymer F2 is the same as that for fluorine-containing polymer F1-1 described above. The TQ value of the precursor polymer of fluorine-containing polymer F2 is preferably 100°C or higher, more preferably 150°C or higher, even more preferably 200°C or higher, and particularly preferably 230°C or higher. Furthermore, the TQ value is preferably 350°C or lower, more preferably 290°C or lower, even more preferably 270°C or lower, and particularly preferably 250°C or lower. 【0082】Methods for producing solid polymer electrolyte membranes include a method in which a liquid composition containing a polymer and a liquid medium is applied to a substrate film or catalyst layer and dried (casting method), and a method in which a precursor polymer is formed to obtain a precursor membrane, and then groups in the precursor membrane that can be converted into ion exchange groups are converted into ion exchange groups. 【0083】 Methods for forming a precursor film include melt extrusion and hot press molding, with hot press molding being preferred. Known hot press equipment such as flat plate presses and roll presses can be used for hot press molding. 【0084】 The deposition temperature when forming a fluorine-containing polymer (I') film is preferably lower than the TQ value of the fluorine-containing polymer (I'). The difference between the TQ value of the fluorine-containing polymer (I') and the deposition temperature is preferably 5°C or more, more preferably 10°C or more, and even more preferably 20°C or more. Furthermore, the above difference is preferably 50°C or less, more preferably 40°C or less, and even more preferably 35°C or less. 【0085】 Specific examples of methods for converting groups in the precursor film that can be converted into ion exchange groups include methods of subjecting the precursor film to hydrolysis or acidification, and a preferred method is to bring the precursor film into contact with an alkaline aqueous solution. Specific examples of methods for bringing the precursor film into contact with an alkaline aqueous solution include immersing the precursor film in an alkaline aqueous solution and spraying the alkaline aqueous solution onto the surface of the precursor film. The hydrolysis temperature is preferably 0 to 120°C, more preferably 60 to 110°C, and even more preferably 90 to 100°C. 【0086】 After the hydrolysis treatment described above, it is preferable to wash the obtained film with water. Alternatively, the obtained film may be brought into contact with an acidic aqueous solution to convert the ion exchange groups to the acidic form. 【0087】The solid polymer electrolyte membrane may be reinforced with a reinforcing material. Examples of reinforcing materials include porous materials, fibers, woven fabrics, and nonwoven fabrics. Examples of materials for the reinforcing material include polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer, polyethylene, polypropylene, and polyphenylene sulfide. 【0088】 Solid polymer electrolyte membranes may contain platinum-containing materials. The platinum-containing materials only need to contain platinum atoms. Specific examples of platinum-containing materials include platinum itself, platinum oxides, platinum-containing composite metal oxides, and platinum alloys. A specific example of a platinum-containing composite oxide is M ｘ Pt ３ O ４ (M is at least one metal atom selected from the group consisting of Li, Na, Mg, Ca, Zn, Cd, Co, Ni, Mn, Cu, Ag, Bi, and Ce, and x is greater than 0 and less than or equal to 1.) Specific examples of platinum alloys include alloys containing at least one metal selected from the group consisting of transition metals and noble metals other than platinum, and platinum. 【0089】 Specific examples of the shape of platinum-containing materials include particulate and sheet forms. When the platinum-containing material is particulate, it may be a core-shell type particle. An example of a core-shell type particle is a particle in which the core is carbon or contains a metal other than platinum, and the shell contains platinum atoms. 【0090】 The platinum-containing material may be supported on a carrier. Specific examples of carriers include carbon carriers such as carbon black powder, graphitized carbon, carbon fibers, and carbon nanotubes. 【0091】 The solid polymer electrolyte membrane may contain a cerium-containing material. The cerium-containing material only needs to contain cerium atoms. Specific examples of cerium-containing materials include cerium oxides and cerium-containing composite metal oxides. For example, cerium oxide (CeO) ２ (Cerium(IV) oxide), Ce ２O ３ (Cerium(III) oxide, etc.) These cerium oxides may be doped with polyvalent metal ions such as zirconium and praseodymium. The shape of the cerium-containing material is not particularly limited, but particulate form is one example. 【0092】 The thickness of the solid polymer electrolyte membrane is preferably 5 μm or more, more preferably 15 μm or more, even more preferably 25 μm or more, and particularly preferably 40 μm or more. The thickness is preferably 300 μm or less, and more preferably 150 μm or less. The thickness of the solid polymer electrolyte membrane can be measured, for example, using an image obtained by measuring a cross-section cut in the thickness direction of the CCM with an optical microscope, and the arithmetic mean of any eight locations can be used. In addition, if the solid polymer electrolyte membrane is obtained as a single unit, it can also be measured by the method described in the examples below. 【0093】 <Second Catalyst Layer> The CCM may further have a second catalyst layer on the side of the solid polymer electrolyte membrane opposite to the first catalyst layer. That is, the CCM may have the first catalyst layer, the solid polymer electrolyte membrane, and the second catalyst layer in this order. When the first catalyst layer is used as the cathode-side catalyst layer, it is preferable that the second catalyst layer is used as the anode-side catalyst layer. Also, when the first catalyst layer is used as the anode-side catalyst layer, it is preferable that the second catalyst layer is used as the cathode-side catalyst layer. In the CCM of this disclosure, from the viewpoint of hydrogen permeability, it is preferable that the first catalyst layer is used as the cathode-side catalyst layer and the second catalyst layer is used as the anode-side catalyst layer. In other words, in the CCM of this disclosure, it is preferable that the first catalyst layer contains a platinum-containing catalyst and the second catalyst layer contains an iridium-containing catalyst. The preferred embodiment of the second catalyst layer is the same as the first catalyst layer except that it contains a fluorine-containing polymer F1-2, so the explanation is omitted. 【0094】(Fluorine-containing polymer F1-2) The second catalyst layer preferably contains a fluorine-containing polymer F1-2 containing the above-described unit B. The preferred embodiment of unit B is the same as that of the first catalyst layer. The fluorine-containing polymer F1-2 preferably further contains the above-described unit C. The preferred embodiment of unit C is the same as that of the first catalyst layer. The fluorine-containing polymer F1-2 preferably further contains the above-described unit A. The preferred embodiment of unit A is the same as that of the first catalyst layer. The fluorine-containing polymer F1-2 may also contain the above-described unit D. The preferred embodiment of unit D is the same as that of the first catalyst layer. 【0095】 <Method for Manufacturing CCM> As described above, CCM may be manufactured by coating a catalyst ink onto a solid polymer electrolyte membrane, or by forming a catalyst layer on a substrate and then transferring the formed catalyst layer onto a solid polymer electrolyte membrane. From the viewpoint of hydrogen permeability, heating and pressurizing CCM is preferable. The heating temperature is preferably between 130°C and 180°C. When pressurizing is performed with a flat plate press, the surface pressure is preferably 0.2 MPa or more, more preferably 1.0 MPa or more, even more preferably 1.5 MPa or more, and particularly preferably 2.0 MPa or more. Furthermore, the surface pressure is preferably 30.0 MPa or less, more preferably 10.0 MPa or less, and even more preferably less than 3.0 MPa. When pressurizing is performed with a roll press, the linear pressure is preferably 3 kg / cm or more, and also preferably 200 kg / cm or less. 【0096】 [Membrane Electrode Assembly] The membrane electrode assembly of this disclosure includes the solid polymer electrolyte membrane of this disclosure. Preferably, the membrane electrode assembly of this disclosure comprises an anode having the first catalyst layer, a cathode having the second catalyst layer, and the solid polymer electrolyte membrane disposed between the anode and the cathode. Alternatively, the membrane electrode assembly of this disclosure may also comprise an anode having the second catalyst layer, a cathode having the first catalyst layer, and the solid polymer electrolyte membrane disposed between the anode and the cathode. An example of the membrane electrode assembly of this disclosure will be described with reference to the drawings. 【0097】Figure 1 is a cross-sectional view showing an example of a membrane electrode assembly according to the present disclosure. The membrane electrode assembly 10 comprises an anode 13 having a catalyst layer 11 and a gas diffusion layer 12, a cathode 14 having a catalyst layer 11 and a gas diffusion layer 12, and a solid polymer electrolyte membrane 15 disposed between the anode 13 and the cathode 14 in contact with the catalyst layer 11. Here, at least one of the catalyst layer 11 of the anode 13 and the catalyst layer 11 of the cathode 14 is the first catalyst layer described above. The membrane electrode assembly 10 in Figure 1 includes a gas diffusion layer 12, but the gas diffusion layer is an arbitrary component and does not have to be included in the anode 13 and the cathode 14. 【0098】 The catalyst layers (first catalyst layer and second catalyst layer) are as described above. 【0099】 The gas diffusion layer has the function of uniformly diffusing gas into the catalyst layer and also functions as a current collector. Specific examples of the gas diffusion layer include carbon paper, carbon cloth, carbon felt, and metal mesh. It is preferable to use a metal mesh as the gas diffusion layer on the anode side. The metal material constituting the metal mesh is preferably a metal with high corrosion resistance, such as titanium, zirconium, niobium, and tantalum, with titanium being preferred. The gas diffusion layer may be treated to be water-repellent with PTFE or the like. If the gas diffusion layer is a metal mesh, its surface may be coated with a precious metal such as platinum. The gas diffusion layer may also contain the catalyst mentioned above. 【0100】 The film thickness of the anode and cathode is preferably 5 to 100 μm, more preferably 5 to 50 μm, even more preferably 5 to 30 μm, and particularly preferably 5 to 15 μm, independently of each other. The film thickness of the anode and cathode can be measured, for example, using an image obtained by measuring a cross-section of the film electrode assembly cut in the thickness direction with a laser microscope, and the arithmetic mean value can be taken at any 20 locations. 【0101】[Water Electrolyzer] The water electrolyzer of the present disclosure includes the membrane electrode assembly described above. An example of a PEM water electrolyzer including the membrane electrode assembly of the present disclosure is a PEM water electrolyzer having the membrane electrode assembly, a water supply unit that supplies water to the anode catalyst layer, and a power supply unit that is electrically connected to the anode catalyst layer and the cathode catalyst layer. In the PEM water electrolyzer, when water is supplied to the anode catalyst layer by the water supply unit and a DC voltage is applied between the anode and cathode by the power supply unit, water is decomposed by an electrochemical reaction on the anode catalyst layer side to generate oxygen gas and protons, and at the same time, electrons flow to the power supply unit. On the cathode catalyst layer side, protons are supplied to the cathode catalyst layer side via a solid polymer electrolyte membrane, and hydrogen gas is generated by obtaining electrons supplied from the power supply unit. A PEM water electrolyzer having a membrane electrode assembly may have the same configuration as a known water electrolyzer, except for having the above-described components (for example, an oxygen recovery member for recovering generated oxygen, a hydrogen recovery member for recovering generated hydrogen). 【0102】 [Method for Producing Hydrogen] The method for producing hydrogen according to this disclosure is a method for producing hydrogen by electrolyzing water (electrolyte) using the water electrolysis apparatus described above. With the method for producing hydrogen according to this disclosure, hydrogen can be produced efficiently because the water electrolysis apparatus of this disclosure is used. 【0103】 The present invention will be described in more detail below based on examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following examples. Examples 1, 2, 7, and 8 below are examples, and Examples 3 to 6 are comparative examples. 【0104】 [Measurement Method] <Ion Exchange Capacity> After vacuum drying, the fluorine-containing polymer is weighed and placed in a polycarbonate container, and then subjected to a 0.7 mol / L NaOH solution (solvent: H ２ O / CH ３ Immerse in OH = 10 / 90 (mass ratio) at 60°C for 72 hours or more to obtain -SO in fluorine-containing polymers. ２The F group was completely converted to the Na salt form. The NaOH solution after immersion was back-titrated with 0.1 mol / L HCl using phenolphthalein as an indicator, and the amount of NaOH in the solution was determined to calculate the ion exchange capacity (milliequivalents / g dry resin). Note that "meq / g" refers to "milliequivalents / g dry resin," which is the unit of ion exchange capacity. 【0105】 <Percentage of each unit> The percentage of each unit in polymer X, described later, was calculated from the ion exchange capacity measurement results mentioned above and the amount of each monomer used in the production of the polymer. The percentage of each unit in polymer Y, described later, １９ The values ​​were calculated from F-NMR measurements. Note that the content of each unit in the fluorine-containing polymer with ion exchange groups (hereinafter also referred to as "polymer H") is approximately equivalent to the content of each unit in the precursor polymer (polymer F). １９ F-NMR measurements were performed at a frequency of 282.7 MHz, with chemical shift reference: CFCl. ３ The measurements were taken under the specified conditions. The compositional analysis of polymer F was performed by adjusting the solution concentration to 10% by mass using hexafluorobenzene as the dissolving solvent. 【0106】 <TQ Value> Using a flow tester (Shimadzu Corporation, CFT-500D) equipped with a nozzle 1 mm in length and 1 mm in inner diameter, particles containing a fluorine-containing polymer after vacuum drying were melt-extruded at an extrusion pressure of 2.94 MPa (gauge pressure) while varying the temperature. The polymer extrusion volume was 100 mm. ３ The TQ value, which is the temperature at which the temperature is measured per second, was calculated. 【0107】<Softening Temperature> The softening temperature of polymer H was measured by the following method. Liquid compositions S (liquid compositions S-1 and S-2 described later), in which polymer H was dispersed in a liquid medium, were cast into a petri dish and then annealed to prepare a solid polymer electrolyte membrane. Dynamic viscoelasticity measurements were performed on this solid polymer electrolyte membrane using a dynamic viscoelasticity measuring device (DVA-225, manufactured by IT Measurement Control Co., Ltd.) under the following conditions: sample width: 5.0 mm, gripping distance: 15 mm, measurement frequency: 1 Hz, heating rate: 2 °C / min, and tensile mode. The tanδ (loss tangent) was calculated from the ratio of the loss modulus E'' to the storage modulus E' (E'' / E'), and a tanδ-temperature curve was created. The peak temperature between -100 and 200 °C read from the tanδ-temperature curve was defined as the softening temperature of polymer H. 【0108】 <Thickness of the Electrolyte Membrane> The electrolyte membrane was placed on a dial gauge stand 7002 (Mitutoyo), and the thickness of nine points was measured using a digital gauge 543-250 (manufactured by Mitutoyo Corporation) with a flat terminal of 5 mm in diameter attached to its tip. The arithmetic mean was taken as the thickness of the electrolyte membrane. Specifically, the electrolyte membrane obtained by the method described later in [Method for Manufacturing the Electrolyte Membrane] was cut into a 7.0 cm x 7.0 cm square, and the thickness of nine points (nine points placed at 2 cm intervals with a reference point 0.5 mm inward from each side) was measured at equal intervals on the four sides and diagonals. The arithmetic mean of these nine points was taken as the thickness of the electrolyte membrane. 【0109】 [Hydrogen Crossover Evaluation] The hydrogen concentration in the gas at the anode side of each CCM was measured according to the following procedure, and the hydrogen crossover was evaluated. The CCM was sandwiched between platinum-plated titanium fiber sintered bodies (manufactured by Bekalt Co., Ltd.) with a thickness of 0.25 mm and a porosity of 60 volume%, and a platinum-plated titanium plate with a straight channel was used as a separator, with an electrode area of ​​16 cm². ２A membrane electrode assembly was incorporated into a single cell for evaluation. When the membrane electrode assembly was clamped, a pressure of 1.3 MPa was applied to the electrode portion. Next, to ensure sufficient water absorption of the fluorine-containing polymer of the CCM, pure water with a conductivity of 1.0 μS / cm or less, at a temperature of 80°C and atmospheric pressure was supplied to the anode and cathode sides at a flow rate of 50 mL / min for 4 hours. Subsequently, pure water with a conductivity of 1.0 μS / cm or less, at a temperature of 80°C was supplied to the anode side at a flow rate of 50 mL / min, while maintaining atmospheric pressure at both the anode and cathode. A high-current potentio / galvanostat HCP-803 (manufactured by Biologic) was used to apply 32 A (current density 2 A / cm²). ２ While maintaining the current, water electrolysis was performed for 4 hours as a break-in period. After that, the current was 0-48A (current density 0-3A / cm²). ２ IV (current-voltage) measurements were performed by gradually increasing the current within the specified range. Four IV measurements were taken. Subsequently, pure water with a conductivity of 1.0 μS / cm or less, a temperature of 80°C, and atmospheric pressure was supplied to the cell at a rate of 50 mL / min. With the back pressure at both the anode and cathode at atmospheric pressure, a high-current potentio / galvanostat HCP-803 (manufactured by Biologic) was used to measure 3.2 A (current density 0.2 A / cm²). ２ ) for 11 hours at 8A (current density 0.5A / cm²) ２ ) for 7 hours at 16A (current density 1A / cm²) ２ ) for 4 hours, and 32A (current density 2A / cm²) ２ The current was maintained for 4 hours. After the holding time for each current had elapsed, water was separated from the gas discharged from the anode side, and the hydrogen concentration in the gas on the anode side was measured using a micro GC (Agilent 490, manufactured by Agilent). Using the hydrogen concentration in the gas (volume %) at the final measurement point, the hydrogen crossover (hydrogen permeability) was evaluated according to the evaluation criteria below. In practical use, A ＋ Evaluation, A rating, B rating, or B － The evaluation was favorable, A ＋ A rating, preferably an A rating or a B rating, ＋ A rating or an A rating is even more preferable. ＋ The evaluation is particularly favorable. A ＋A: Hydrogen concentration in the gas at the anode is 0.05 volume% or less. B: Hydrogen concentration in the gas at the anode is greater than 0.05 volume% and 0.08 volume% or less. B: Hydrogen concentration in the gas at the anode is greater than 0.08 volume% and 0.10 volume% or less. － : The hydrogen concentration in the gas at the anode is greater than 0.10 volume% and less than or equal to 0.12 volume% C: The hydrogen concentration in the gas at the anode is greater than 0.12 volume% 【0110】 [Abbreviations] The manufacturing procedure for each example of CCM is described below. <Monomers> ・TFE: Tetrafluoroethylene monomer m1: 【0111】 【0112】 Monomer m2: CF ２ = CFOCF ２ CF (CF ３ ) O (CF ２ ) ２ SO ２ F 【0113】 【0114】 • Monomer m3: 【0115】 【0116】 <Polymerization Initiators> ・V-601: Dimethyl 2,2'-azobis (2-methylpropionate) ・AIBN: 2,2'-Azobis (isobutyronitrile) ・PFB: CF ３ CF ２ CF ２ C(O)OOC(O)CF ２ CF ２ CF ３ 【0117】 <Solvent> ・HFE-347pc-f: HCF ２ CF ２ OCH ２ CF ３ ・HFC-52-13p:CF ３ (CF ２ ) ４ CF ２ H ・HCFC-225cb: CClF ２CF ２ CHClF ・HCFC-141b:CH ３ CCl ２ F 【0118】 [Synthesis Method of Polymer X] <Fluorine-containing Polymer X1> In a 21,100 mL stainless steel reactor, 6,665 g of monomer m1 and 5,406 g of HCFC-225cb were charged under reduced pressure of -0.1 MPaG while cooled, and the inside was degassed. Then, the mixture was stirred at 142 rpm, the temperature was raised to 70°C, TFE was introduced, and the total pressure was set to 0.96 MPaG. Note that MPaG is the differential pressure (gauge pressure) from atmospheric pressure expressed in MPa. 332 g of an HCFC-225cb solution containing 3.00 mass% AIBN was injected into the reactor under pressure to start polymerization. TFE was continuously added while maintaining the starting pressure. When the amount of TFE continuously added reached 1,297 g, the reactor was cooled to below 20°C, the unreacted TFE was vented, and a liquid composition X1 was obtained, which is a solution in which the fluorine-containing polymer X1 is dissolved in unreacted monomer m1 and HCFC-225cb. 10.0 kg of HCFC-225cb was added to the reactor in several batches, and 11.6 kg of liquid composition X1 was transferred to another tank while being diluted. The diluted liquid composition was kept at 25°C, and 34.5 kg of HCFC-141b at 25°C was quantitatively added and stirred to agglomerate the fluorine-containing polymer X1 and form particles containing the fluorine-containing polymer X1. After stirring, the liquid containing the particles containing the fluorine-containing polymer X1 was filtered using a filter cloth. The separated and recovered particles containing the fluorine-containing polymer X1 were washed by adding a mixed solvent of 10.0 kg of HCFC-141b and 5.0 kg of HCFC-225cb at 25°C, stirring, and then filtering. The washing process was repeated a total of five times to obtain particles containing the fluorine-containing polymer X1. The particles containing the fluorine-containing polymer X1 were vacuum-dried at 90°C for 16 hours to obtain 2,189 g of the fluorine-containing polymer X1. The ion exchange capacity of the fluorine-containing polymer X1 was 1.21 meq / g, and the TQ value was 269°C. Furthermore, the content of units based on TFE relative to the total units contained in the fluorine-containing polymer X1 was 91 mol%, and the ratio of units based on TFE to units based on monomer m1 was 91:9 in molar ratio. 【0119】 <Synthesis of Fluorine-Containing Polymer X2> 113 g of monomer m1 and 16.8 g of HFC-52-13p were charged into a 230 mL stainless steel reactor, and freeze-degassing was thoroughly carried out using liquid nitrogen. Then, the temperature was raised to 65°C while stirring at 300 rpm, TFE was introduced, and the total pressure was set to 1.10 MPaG. AIBN was dissolved in HFC-52-13p at a concentration of 2.58 mass% to prepare an initiator solution, and 3.08 g of the initiator solution was injected into the reactor under pressure to start polymerization. TFE was continuously added while maintaining the starting pressure. When the amount of continuously added TFE reached 11.6 g, the reactor was cooled to 10°C, unreacted TFE was vented, and a liquid composition X2 was obtained, which is a solution in which fluorine-containing polymer X2 is dissolved in unreacted monomer m1 and HFC-52-13p. 134 g of liquid composition X2 was kept at 25°C and added to 395 g of HFE-347pc-f at 25°C. The mixture was stirred to agglomerate the fluorine-containing polymer X2 and form particles containing the fluorine-containing polymer X2. After stirring, the liquid containing the particles with the fluorine-containing polymer X2 was filtered using filter paper. The separated and recovered particles containing the fluorine-containing polymer X2 were washed by adding 154 g of HFE-347pc-f at 25°C, stirring, and then filtering. The washing process was repeated a total of three times to obtain particles containing the fluorine-containing polymer X2. The particles containing the fluorine-containing polymer X2 were vacuum-dried at 240°C for 16 hours to obtain 22.3 g of fluorine-containing polymer X2. The ion exchange capacity of the fluorine-containing polymer X2 was 1.68 meq / g, and the TQ value was 250°C. Furthermore, in the fluorine-containing polymer X2, the content of units based on TFE relative to the total units contained in the fluorine-containing polymer X2 was 85 mol%, and the ratio of units based on TFE to units based on monomer m1 was 85:15 in molar ratio. 【0120】<Fluorine-containing polymer X3> Fluorine-containing polymer X3 was manufactured with reference to the description in paragraph 0197 of Japanese Patent Publication No. 2015-099772. The ion exchange capacity of fluorine-containing polymer X3 was 1.25 meq / g, and the TQ value was 225°C. Furthermore, the content of units based on TFE relative to the total units contained in fluorine-containing polymer X3 was 78 mol%, and the ratio of units based on TFE to units based on monomer m2 was 78:22 in molar ratio. 【0121】 [Method for Manufacturing Electrolyte Membranes] Using the fluorine-containing polymers obtained in the above procedure, electrolyte membranes were obtained by the following method. First, each fluorine-containing polymer (precursor polymer) was press-molded by holding it at 0.5 MPa, 2 MPa, 4 MPa, 6 MPa, 8 MPa, 10 MPa, 12 MPa, and 15 MPa for 5 minutes at a temperature 30°C lower than the TQ value of each fluorine-containing polymer, thereby obtaining fluorine-containing polymer films (film thickness 45-70 μm). The obtained films were immersed in a potassium hydroxide / methanol / water = 15 / 20 / 65 (mass ratio) solution at 95°C for 16 hours, and then immersed in ultrapure water at 95°C for 30 minutes. This process was repeated twice to remove the -SO4 from the fluorine-containing polymer. ２ The F group is hydrolyzed, and -SO ３ The K group was converted. Furthermore, by repeating the process of immersing the polymer in a 3 mol / L hydrochloric acid aqueous solution at 80°C for 30 minutes, followed by immersion in ultrapure water at 80°C for 30 minutes, 10 times, the fluorine-containing polymer was converted to -SO ３ K group -SO ３ The H group was converted. Then, the resulting membrane was sandwiched between filter paper and air-dried to obtain electrolyte membranes M1 to M3. 【0122】[Synthesis Method of Polymer Y] [Polymer Y1] A stainless steel autoclave with an internal volume of 2,575 mL was reduced in pressure under an ice bath, and 1,116.02 g of monomer m1, 340.92 g of monomer m3, 407.78 mg of PFB solution dissolved in HFC-52-13p at a concentration of 3.2 mass%, and 172.0 g of HFC-52-13p were aspirated and charged into the autoclave, and the pressure was reduced again. Then, 56.90 g of TFE was charged, and the temperature was raised to 24°C to start the reaction. Stirring during the reaction was carried out with a double helical ribbon impeller, and the stirring speed was set to 60 rpm until 2.5 hours after the start of the reaction, 30 rpm from 2.5 hours to 3.5 hours, and 10 rpm from 3.5 hours to 10 hours. After stirring for 10 hours, the autoclave was reduced in pressure and unreacted monomer m3 and TFE were removed by distillation. The product was then diluted with HFC-52-13p, and this was mixed with a mixture of HFC-52-13p:methanol = 8:2 (mass ratio) to agglomerate the polymer and filter it. The filtered polymer was washed with a mixture of HFC-52-13p:methanol = 7:3 (mass ratio), separated by filtration, and the solids were dried at 80°C and then vacuum dried at 210°C to obtain polymer Y1. 【0123】 [Polymer Y2] 123.8 g of monomer m2, 35.2 g of HCFC-225cb (liquid medium), and 63.62 mg of 2,2'-azobis (isobutyronitrile) (polymerization initiator) were charged into an autoclave (internal volume 230 mL, made by Hastelloy), and the mixture was cooled with liquid nitrogen to degass it. The temperature was then raised to 70°C, TFE was introduced into the system, and the pressure was maintained at 1.14 MPaG. Polymerization was carried out by continuously adding TFE to maintain a constant pressure of 1.14 MPaG. After 7.9 hours, when the amount of TFE added reached 12.4 g, the autoclave was cooled and the gas in the system was purged to stop the polymerization. The obtained polymer solution was diluted with HCFC-225cb, and then HCFC-141b was added to induce aggregation. After washing with HCFC-225cb and HCFC-141b, the polymer Y2 was dried to obtain 25.1 g of polymer Y2 consisting of a copolymer containing units based on TFE and monomer m2. 【0124】[Polymer Y3] Polymer Y3 was obtained in the same manner as Polymer Y1, except that the amount of monomers and other factors were adjusted so that the constituent units of the polymer were in the ratios shown in Table 1. 【0125】 The constituent unit ratios of polymer Y1, polymer Y2, and polymer Y3, as well as their TQ values, are shown in Table 1 below. 【0126】 【0127】 [Synthesis of Polymer H] Using polymers Y1 to Y3 respectively, powders of polymers H1 to H3 were obtained by the following method. First, polymers Y1 to Y3 were cooled with dry ice and then pulverized. Next, polymers Y1 to Y3, which had been pulverized at 80°C, were each immersed in the alkaline aqueous solution shown in Table 2 for 40 hours to obtain the -SO ２ Hydrolyze F to obtain -SO ３ The polymer was converted to K. Furthermore, the obtained polymer was immersed in a 3 mol / L hydrochloric acid aqueous solution at 80°C for 30 minutes, and then immersed in ultrapure water at 80°C for 30 minutes. The cycle of immersion in the hydrochloric acid aqueous solution and immersion in ultrapure water was performed a total of 10 times, and the polymer was converted to -SO ３ K to -SO ３ The polymers were converted to H. After the above conversion, the polymers were repeatedly washed with ultrapure water until the pH of the water in which they were immersed reached 7. They were dried using a nitrogen flow to obtain powders of each polymer H. The results are shown in Table 2. In Table 2, the ion exchange capacity and softening temperature of polymers H1 to H3 are values ​​measured by the method described above. 【0128】 In Table 2, aqueous solution A has a mass ratio of potassium hydroxide / dimethyl sulfoxide / water = 15 / 30 / 55, and aqueous solution B has a mass ratio of potassium hydroxide / methanol / water = 15 / 20 / 65. 【0129】 【0130】[Preparation of Liquid Composition] [Liquid Composition S-1] 18.70 g of polymer (powder) (18.22 g of polymer H1, 0.48 g of water, solid content concentration 97.4% by mass), 22.81 g of ultrapure water, and 54.36 g of 1-propanol were added to a 0.2 L glass autoclave. The mixture was stirred at 300 rpm at 115°C for 13 hours, and then diluted with 31.0 g of ultrapure water. After stirring at 110°C for 1 hour, the solution was allowed to cool and removed from the autoclave. This solution was diluted with 25.6 g of ultrapure water and 25.6 g of 1-propanol, stirred at 110°C for 1 hour, allowed to cool, and filtered using a pressure filter (filter paper: Advantec Toyo Co., Ltd., PF040). Following the above procedure, a liquid composition S-1 was obtained in which polymer H1 was dispersed in a liquid medium at a solid content concentration of 10.2% by mass. 【0131】 [Liquid Composition S-2] Liquid composition S-2 was obtained in which polymer H2 was dispersed in the liquid medium at a solid content concentration of 26.0% by mass, in the same manner as liquid composition S-1, except that polymer H2 was used instead of polymer H1, ethanol was used instead of 1-propanol, and the mass of the polymer and the liquid medium was changed. (Solvent: ethanol / water = 60 / 40 (mass ratio)) 【0132】 [Liquid Composition S-3] Liquid composition S-3 was obtained in the same manner as liquid composition S-1, except that polymer H3 was used instead of polymer H1 as a raw material, and polymer H3 was dispersed in a liquid medium at a solid content concentration of 10.2% by mass. 【0133】 [Preparation of composition for catalyst layer formation] [Coating liquid CI-1 for cathode catalyst layer formation] Supported catalyst (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., with a specific surface area of ​​carbon support of 800 m²) in which platinum is supported on carbon powder. ２3.0 g of platinum (average particle size of platinum is 2.8 nm) was prepared, and 23.6 g of water and 13.9 g of 1-propanol were added and mixed. 11.1 g of liquid composition S-1 was added to this mixture to achieve an I / C ratio of 0.7 and a solid content concentration of 8.0% by mass. After addition, the mixture was dispersed using 5 mm zirconia beads in a planetary ball mill (Ito Seisakusho, model: LP-4) at a rotation speed of 300 rpm for 90 minutes. Then, 10.5 g of water and 6.9 g of 1-propanol were added to dilute the mixture so that the solid content concentration after dispersion was 6.0% by mass, obtaining the cathode catalyst layer forming coating liquid CI-1. 【0134】 [Coating liquid CI-2 for cathode catalyst layer formation] 85.0 g of a supported catalyst (TEC10E50E, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) in which platinum was supported at a concentration of 46.2% by mass on carbon powder was prepared, and 498.4 g of water and 361.1 g of ethanol were added and mixed. To this, a mixture (247.9 g) was prepared by pre-mixing and kneading 160.2 g of liquid composition S-2, 87.4 g of ethanol, and 51.1 g of Zeolora-H (manufactured by Nippon Zeon Co., Ltd.), resulting in an I / C ratio of 0.7 and a solid content concentration of 10.1% by mass. After addition, the mixture was dispersed using 5 mm zirconia beads in a planetary ball mill (manufactured by Ito Seisakusho, model: LP-4) at a rotation speed of 300 rpm for 90 minutes to obtain coating liquid CI-2 for cathode catalyst layer formation. 【0135】 [Coating liquid CI-3 for cathode catalyst layer formation] A coating liquid CI-3 for cathode catalyst layer formation was obtained in the same manner as the coating liquid CI-1, except that liquid composition S-3 was used instead of liquid composition S-1. 【0136】 [Anode catalyst layer forming coating liquid AI-1] Add ethanol (6.4 g) and water (6.5 g) to liquid composition S-1 (9.2 g), and further add iridium at a specific surface area of ​​100 m². ２ 5.0 g of iridium oxide catalyst (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) was added in an amount equal to 0.25 I / Ir. The resulting mixture was treated with a planetary bead mill (rotation speed 300 rpm) for 90 minutes to obtain a coating liquid AI-1 for anode catalyst layer formation with a solid content concentration of 21.9% by mass. 【0137】[Anode Catalyst Layer Forming Coating Liquid AI-2] To liquid composition S-2 (17.0 g), ethanol (9.2 g) and Zeolora-H (manufactured by Nippon Zeon) (5.4 g) were added and mixed for 15 minutes at 2200 rpm in a rotational and revolving mixer (manufactured by Shinky, Awatori Rentaro). To the mixed composition (13.4 g), ethanol (11.7 g) and water (18.9 g) were added, and further a specific surface area of ​​100 m² containing 74.8% by mass of iridium was added. ２ 5.0 g of iridium oxide catalyst (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) was added at a concentration of I / Ir of 0.25. The resulting mixture was treated with a planetary bead mill (rotation speed 300 rpm) for 90 minutes to obtain a coating solution AI-2 for anode catalyst layer formation with a solid content concentration of 22.0 mass%. 【0138】 [Example 1] A cathode catalyst layer forming solution CI-1 was applied to an ETFE (ethylene tetrafluoroethylene) sheet using a die coater, dried at 80°C for 10 minutes, and then heat-treated at 150°C for 15 minutes, resulting in a thickness of 14 μm and a platinum content of 0.4 mg / cm². ２ A cathode catalyst layer CC-1 was obtained. Furthermore, on another ETFE sheet, a coating solution AI-2 for forming an anode catalyst layer was applied at an iridium concentration of 1.0 mg / cm³. ２ The material was coated using an applicator, dried at 80°C for 10 minutes, and then heat-treated at 150°C for 15 minutes to obtain a 14 μm thick anode catalyst layer AC-2. 【0139】 One side of the solid polymer electrolyte membrane (M1), cut to 7 cm x 7 cm, was positioned opposite the side containing the anode catalyst layer AC-2, cut to 4.0 cm x 4.0 cm, and the other side of the solid polymer electrolyte membrane, cut to 4.0 cm x 4.0 cm, was positioned opposite the side containing the cathode catalyst layer CC-1, cut to 4.0 cm. The membrane was then heated and pressed at a press temperature of 160°C for 10 minutes at a pressure of 2.6 MPa. After lowering the temperature to 70°C, the pressure was released and the membrane was removed. The ETFE sheets of the anode catalyst layer and the cathode catalyst layer were peeled off, resulting in an electrode area of ​​16 cm². ２ We obtained CCM (ME-1). 【0140】[Examples 2 to 8] In the same manner as in Example 1, CCMs (ME-2 to ME-8) were obtained in which the anode catalyst layer, solid polymer electrolyte membrane, and cathode catalyst layer shown in Table 3 below were arranged in this order. 【0141】 [Results] The composition of the CCM obtained by the above procedure and the evaluation of the hydrogen permeability of the obtained CCM are shown in Table 3 below. 【0142】 【0143】 A CCM having a first catalyst layer and a solid polymer electrolyte membrane, wherein the first catalyst layer contains a fluorine-containing polymer F1-1 containing units having a cyclic ether structure and units having ion exchange groups, and the solid polymer electrolyte membrane contains a fluorine-containing polymer F2 containing units represented by formula (1), and the ion exchange capacity of the fluorine-containing polymer F2 is 1.65 milliequivalents / g dry resin or less, is considered to have low hydrogen permeability. On the other hand, in a CCM, if the catalyst layer does not contain the fluorine-containing polymer F1-1, the hydrogen permeability is considered to be higher than that of Examples 1 and 2 (Example 3). Furthermore, in a CCM, if the ion exchange capacity of the fluorine-containing polymer contained in the solid polymer electrolyte membrane is greater than 1.65 milliequivalents / g dry resin, the hydrogen permeability is considered to be higher than that of Examples 1 and 2 (Example 4). Furthermore, in the CCM, if the above-mentioned fluorine-containing polymer F2 is not included, it is considered that the hydrogen permeability will be higher than in Examples 1, 2, 7, and 8 (Examples 5 and 6). From a comparison between Example 1 and Example 2, it is considered that when the first catalyst layer containing the above-mentioned fluorine-containing polymer F1-1 is placed on the cathode side, the hydrogen permeability will be even lower. 【0144】 10 Membrane electrode assembly 11 Catalyst layer 12 Gas diffusion layer 13 Anode 14 Cathode 15 Solid polymer electrolyte membrane 【0145】 Furthermore, the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2024-217502, filed on December 12, 2024, are incorporated herein by reference as disclosure of the present invention.

Claims

A solid polymer electrolyte membrane with a catalyst layer having a first catalyst layer and a solid polymer electrolyte membrane, wherein the first catalyst layer contains a fluorine-containing polymer F1-1 that includes units having a cyclic ether structure and units having ion exchange groups, The solid polymer electrolyte membrane comprises a fluorine-containing polymer F2 having two or more ion-exchange groups, A solid polymer electrolyte membrane with a catalyst layer, wherein the ion exchange capacity of the fluorine-containing polymer F2 is 1.65 milliequivalents / g dry resin or less. 　 The solid polymer electrolyte membrane according to claim 1, wherein the unit having two or more ion exchange groups includes a unit represented by formula (A-2). R Ｆ１ and R Ｆ２ Each of these independently comprises a perfluoroalkylene group having 1 to 3 carbon atoms, or a perfluoroalkylene group with -CF ２ The negative sign is a divalent group substituted with an etheric oxygen atom. R Ｆ３ This is a perfluoroalkylene group having 1 to 6 carbon atoms. M ＋ H ＋ , a monovalent metal cation or an ammonium ion in which one or more hydrogen atoms may be substituted with a hydrocarbon group. 2 M ＋ They may be the same or different from one another. m is either 0 or 1. The catalyst layer-equipped solid polymer electrolyte membrane according to claim 1, wherein the ion exchange capacity of the fluorine-containing polymer F2 is 1.00 to 1.40 milliequivalents / g dry resin. 　 The solid polymer electrolyte membrane with a catalyst layer according to claim 1, wherein the thickness of the solid polymer electrolyte membrane is 25 to 150 μm. 　 The catalyst layer-equipped solid polymer electrolyte membrane according to claim 1, wherein the number of ion exchange groups in the ion exchange group-containing unit of the fluorine-containing polymer F1-1 is two or more. The catalyst layer-equipped solid polymer electrolyte membrane according to claim 1, wherein the ion exchange capacity of the fluorine-containing polymer F1-1 is 0.85 to 1.05 milliequivalents / g dry resin. The catalyst layer-equipped solid polymer electrolyte membrane according to claim 1, wherein the fluorine-containing polymer F1-1 and fluorine-containing polymer F2 further comprise units based on fluorine-containing olefins. 　 The catalyst layer-equipped solid polymer electrolyte membrane according to claim 7, wherein the fluorine-containing olefin is tetrafluoroethylene. 　 The solid polymer electrolyte membrane with a catalyst layer according to claim 1, further comprising a second catalyst layer on the side of the solid polymer electrolyte membrane opposite to the first catalyst layer side. 　 The catalyst layer-equipped solid polymer electrolyte membrane according to claim 9, wherein the first catalyst layer contains a platinum-containing catalyst and the second catalyst layer contains an iridium-containing catalyst. 　 The solid polymer electrolyte membrane with a catalyst layer according to claim 9, wherein the second catalyst layer comprises a fluorine-containing polymer F1-2, and the fluorine-containing polymer F1-2 comprises units having ion exchange groups and units having a cyclic ether structure. 　 A membrane electrode assembly comprising a solid polymer electrolyte membrane with a catalyst layer according to any one of claims 1 to 11. 　 A water electrolysis apparatus comprising the membrane electrode assembly described in claim 12. 　 A method for producing hydrogen, comprising producing hydrogen by electrolyzing water using the water electrolysis apparatus described in claim 13.

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