Solid polymer electrolyte membrane, membrane-electrode assembly, water electrolysis device, method for producing hydrogen, and method for producing solid polymer electrolyte membrane

Abstract

The present invention provides a solid polymer electrolyte membrane which has high durability during electrolysis and excellent proton conductivity.　Provided is a solid polymer electrolyte membrane which contains a fluorine-containing polymer that comprises a unit having two or more ion exchange groups, wherein: the ion exchange capacity of the fluorine-containing polymer is 0.70-1.55 milliequivalents / g dry resin; and in the infrared spectrum obtained by measuring the fluorine-containing polymer by infrared spectroscopy, the ratio of the maximum absorbance I1690 at 1,690 ± 10 cm-1 to the maximum absorbance I2350 at 2,350 ± 30 cm-1 is 0.150 or less.

Description

Solid polymer electrolyte membrane, membrane electrode assembly, water electrolysis device, hydrogen production method, and solid polymer electrolyte membrane production method 【0001】 This disclosure relates to a solid polymer electrolyte membrane. This disclosure also relates to a membrane electrode assembly including the solid polymer electrolyte membrane, a water electrolysis apparatus including the membrane electrode assembly, a method for producing hydrogen using the water electrolysis apparatus, and a method for producing the solid polymer electrolyte membrane. 【0002】 Solid polymer electrolyte membranes can be applied to a variety of uses, and various studies have been conducted on them. For example, a solid polymer electrolyte membrane is applied to solid polymer water electrolysis devices and the like as a membrane electrode assembly with a catalyst layer and electrodes on both sides. An example of such a solid polymer electrolyte membrane is the one described in Patent Document 1. 【0003】 Patent Document 1 discloses a solid polymer electrolyte membrane formed using a copolymer of tetrafluoroethylene and a vinyl fluoride compound having a sulfonic acid group. The disclosed solid polymer electrolyte membrane has an equivalent mass of 790 g / eq. 【0004】 International Publication No. 2018 / 047925 【0005】 When the solid polymer electrolyte membrane described in Patent Document 1 was applied to a water electrolysis apparatus, it was found that its durability during electrolysis did not meet the standards required today, indicating room for improvement. Furthermore, in order to reduce the electrolysis voltage, the solid polymer electrolyte membrane used in a water electrolysis apparatus needs to have excellent proton conductivity. 【0006】 This disclosure has been made in view of the above-mentioned problems, and the problem that one embodiment of this invention aims to solve is to provide a solid polymer electrolyte membrane that has high durability during electrolysis and excellent proton conductivity. Another problem that one embodiment of this invention aims to solve is to provide a membrane electrode assembly, a water electrolysis apparatus, a method for producing hydrogen, and a method for producing a solid polymer electrolyte membrane. 【0007】This disclosure includes the following embodiments: [1] A solid polymer electrolyte membrane for a water electrolysis apparatus, wherein the solid polymer electrolyte membrane comprises a fluorine-containing polymer having two or more ion exchange groups, the ion exchange capacity of the fluorine-containing polymer is 0.70 to 1.50 milliequivalents / gram dry resin, and the infrared spectrum obtained by measuring the fluorine-containing polymer by infrared spectroscopy is 2350 ± 30 cm⁻¹ －１ Maximum absorbance I ２３５０ 1690 ± 10 cm －１ Maximum absorbance I １６９０ [1] A solid polymer electrolyte membrane in which the ratio of is 0.150 or less. [2] The solid polymer electrolyte membrane according to [1], wherein the ion exchange capacity of the fluorine-containing polymer is 0.90 to 1.35 milliequivalents / gram dry resin. [3] The solid polymer electrolyte membrane according to [1], wherein the ion exchange capacity of the fluorine-containing polymer is 1.25 to 1.50 milliequivalents / gram dry resin. [4] The solid polymer electrolyte membrane according to any one of [1] to [3], wherein the unit having two or more ion exchange groups includes a unit represented by formula (1-3) described later. [5] The solid polymer electrolyte membrane according to [4], wherein the fluorine-containing polymer includes a unit based on tetrafluoroethylene and a unit represented by formula (1-3) described later, the content of the unit based on tetrafluoroethylene is 86 to 95 mol% of the total units in the fluorine-containing polymer, and the content of the unit represented by formula (1-3) is 5 to 14 mol% of the total units in the fluorine-containing polymer. [6] A solid polymer electrolyte membrane according to any one of [1] to [5], wherein the film thickness is 50 to 150 μm. [7] A solid polymer electrolyte membrane according to any one of [1] to [6], wherein the amount of fluoride ions eluted in the Fenton test is 0.02% by mass or less relative to the total mass of fluorine atoms in the electrolyte membrane. [8] In the infrared spectrum obtained by measuring the above fluorine-containing polymer by infrared spectroscopy, the infrared spectrum is 2350 ± 30 cm⁻¹. －１ Maximum absorbance I ２３５０ 1690 ± 10 cm －１ Maximum absorbance I １６９０The ratio is 0.070 or less, the solid polymer electrolyte membrane according to any one of [1] to [7]. [9] An anode having a catalyst layer, a cathode having a catalyst layer, and the solid polymer electrolyte membrane according to any one of [1] to [8] disposed between the anode and the cathode, a membrane electrode assembly.

[10] A water electrolysis device including the membrane electrode assembly according to [9].

[11] When water is electrolyzed, the hydrogen permeation coefficient at 2 A / cm ２ is 2.8×10 －６ cc·cm / cm ２ ·sec·atm or less, the water electrolysis device according to

[10] .

[12] A method for producing hydrogen by electrolyzing water using the water electrolysis device according to

[10] or

[11] .

[13] After copolymerizing a fluorine-containing olefin and a monomer having two or more groups that can be converted into ion-exchange groups, contacting with a gas containing 5% to 40% by volume of fluorine gas, forming the obtained polymer to obtain a precursor membrane, and then converting the groups that can be converted into ion-exchange groups in the precursor membrane into ion-exchange groups, The ion exchange capacity is 0.70 to 1.50 meq / g of dry resin, In the infrared spectrum obtained by measurement by infrared spectroscopy, the ratio of the maximum absorbance I －１ at 2350±30 cm ２３５０ to the maximum absorbance I －１ at 1690±10 cm １６９０ is 0.150 or less, a method for producing a solid polymer electrolyte membrane including a fluorine-containing polymer.

[14] The production method according to

[13] , wherein the temperature of the fluorination treatment is 150 to 250°C.

[15] The production method according to

[13] or

[14] , wherein the time of the fluorination treatment is from 1 to 7 hours. 【0008】 According to an embodiment of the present invention, a solid polymer electrolyte membrane with high durability during electrolysis and excellent proton conductivity is provided. Also, according to an embodiment of the present invention, a membrane electrode assembly, a water electrolysis device, a method for producing hydrogen, and a method for producing a solid polymer electrolyte membrane are provided. 【0009】 It is a 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. “Ion exchange group” means a group capable of exchanging at least some of the ions it contains with other ions, such as the sulfonic acid type functional group and the carboxylic acid type functional group described below. “Sulfonic acid type functional group” means a sulfonic acid group (-SO ３ H), or sulfonic acid base (-SO ３ M ２ However, M ２ (is an alkali metal or quaternary ammonium cation.) Here, the form of the sulfonic acid base is, for example, (-SO ３ － ) Ma ＋ , (-SO ３ － ) ２ Mb ２＋ , and, (-SO ３ － ) 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. "Carboxylic acid-type functional group" refers to a carboxylic acid group (-COOH) or a carboxylic acid base (-COOM). １ However, M １ (is an alkali metal or quaternary ammonium cation.) Here, the form of the carboxylic acid base is, 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. A "precursor membrane" is a membrane containing a polymer that has groups that can be converted into ion exchange groups. "Groups that can be converted into ion exchange groups" means groups that can be converted into ion exchange groups by treatments such as hydrolysis and acidification. "Groups that can be converted into sulfonic acid-type functional groups" means groups that can be converted into sulfonic acid-type functional groups by treatments such as hydrolysis and acidification. "Groups that can be converted into carboxylic acid-type functional groups" means groups that can be converted into 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 one monomer molecule, formed by the polymerization of monomers. A unit may be an atomic group directly formed by a polymerization reaction, or it may be an atomic group in which a portion of the atomic group is converted to a different structure by processing the polymer obtained by the polymerization reaction. 【0012】 Numerical ranges expressed using "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits. In numerical ranges described stepwise in this specification, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described stepwise. Also, in numerical ranges described in this specification, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. 【0013】 [Solid Polymer Electrolyte Membrane] The solid polymer electrolyte membrane of this disclosure contains a fluorine-containing polymer (hereinafter also referred to as "fluorine-containing polymer (I)") which has two or more ion exchange groups, and the ion exchange capacity of the fluorine-containing polymer is 0.70 to 1.55 milliequivalents / gram dry resin. Furthermore, in the infrared spectrum obtained by measuring the fluorine-containing polymer by infrared spectroscopy, the infrared spectrum is 2350 ± 30 cm⁻¹. －１ Maximum absorbance I ２３５０ 1690 ± 10 cm －１ Maximum absorbance I １６９０The ratio is 0.150 or less. Below, in the infrared spectrum, 2350 ± 30 cm⁻¹ －１ Maximum absorbance I ２３５０ 1690 ± 10 cm －１ Maximum absorbance I １６９０ The ratio of is simply called "I １６９０ / I ２３５０ It is also said as "." 【0014】 The mechanism by which the solid polymer electrolyte membrane of this disclosure exhibits high durability during electrolysis and excellent proton conductivity is not entirely clear, but the inventors speculate as follows: The fluorine-containing polymer contained in the solid polymer electrolyte membrane of this disclosure is I １６９０ / I ２３５０ This is within the specified range. １６９０ / I ２３５０ This will be explained in detail later, but it is thought to correspond to the amount of COOH groups contained in the fluorine-containing polymer. Since COOH groups are thought to be the starting point for the decomposition of the fluorine-containing polymer during electrolysis, it is preferable to keep it at 0.150 or less. In addition, the fluorine-containing polymer contains units having two or more ion exchange groups. In a fluorine-containing polymer containing units having two or more ion exchange groups, within the above range of ion exchange capacity, the content of units containing ion exchange groups, which tend to form bulky structures, decreases. As a result, the amount of gas permeate during electrolysis tends to decrease, and it is thought that oxygen generated on the anode side during electrolysis does not easily permeate to the cathode side. Therefore, oxygen that permeates to the cathode side can become a source of radicals that attack the fluorine-containing polymer. １６９０ / I ２３５０ The synergistic effect of the fact that the value is below a predetermined level is thought to result in high durability during electrolysis. Furthermore, the fluorine-containing polymer (I) contained in the solid polymer electrolyte membrane of this disclosure is thought to have excellent proton conductivity because its ion exchange capacity is within the above range. 【0015】 The structure of the solid polymer electrolyte membrane (hereinafter also simply referred to as the "electrolyte membrane") of this disclosure will be described below. 【0016】<Fluorine-containing polymer> The electrolyte membrane contains a fluorine-containing polymer (fluorine-containing polymer (I)) which includes units having two or more ion exchange groups. The ion exchange capacity of fluorine-containing polymer (I) is 0.70 milliequivalents / gram dry resin or more, preferably 0.90 milliequivalents / gram dry resin or more, more preferably 1.00 milliequivalents / gram dry resin or more, even more preferably 1.15 milliequivalents / gram dry resin or more in terms of superior proton conductivity, particularly preferably 1.20 milliequivalents / gram dry resin or more, and most preferably 1.25 milliequivalents / gram dry resin or more. The ion exchange capacity of fluorine-containing polymer (I) is 1.55 milliequivalents / gram dry resin or less, preferably 1.50 milliequivalents / gram dry resin or less, more preferably 1.48 milliequivalents / gram dry resin or less, even more preferably 1.40 milliequivalents / gram dry resin or less, and particularly preferably 1.35 milliequivalents / gram dry resin or less. The ion exchange capacity of the fluorine-containing polymer (I) is, from the viewpoint of hydrogen permeability, for example, 0.70 to 1.55 milliequivalents / gram dry resin, preferably 0.70 to 1.50 milliequivalents / gram dry resin, more preferably 0.90 to 1.35 milliequivalents / gram dry resin, and even more preferably 1.00 to 1.25 milliequivalents / gram dry resin. The ion exchange capacity of the fluorine-containing polymer (I) is, from the viewpoint of durability and proton conductivity, for example, 0.70 to 1.55 milliequivalents / gram dry resin, preferably 0.70 to 1.50 milliequivalents / gram dry resin, more preferably 0.90 to 1.50 milliequivalents / gram dry resin, even more preferably 1.20 to 1.50 milliequivalents / gram dry resin, particularly preferably 1.25 to 1.50 milliequivalents / gram dry resin, and most preferably 1.35 to 1.50 milliequivalents / gram dry resin. The ion exchange capacity of the fluorine-containing polymer (I) can be determined by the method described in the examples below. 【0017】Specific examples of ion exchange groups include sulfonic acid-type functional groups and carboxylic acid-type functional groups. Sulfonic acid-type functional groups are preferred because they can further reduce the electrolysis voltage when an electrolyte membrane is applied to a water electrolysis device. Furthermore, it is preferable that the membrane does not contain carboxylic acid-type functional groups from the standpoint of applicability to water electrolysis. Units having two or more ion exchange groups are preferably based on perfluorovinyl ether or perfluoroallyl ether, and units based on perfluorovinyl ether are more preferable because they provide superior effects in this disclosure. 【0018】 The fluorine-containing polymer (I) is preferably a copolymer polymer comprising a unit having two or more ion-exchange groups and a unit based on a fluorine-containing olefin. 【0019】 A unit having two or more ion exchange groups preferably contains two or more sulfonic acid-type functional groups and a fluorine atom, and a unit represented by formula (1) is more preferable. Formula (1) -[CF ２ -CF(-L-(SO ３ M) ｎ )]- L is an n+1 valent perfluorohydrocarbon group which may contain an etheric oxygen atom. M is a hydrogen atom, an alkali metal, or a quaternary ammonium cation, and the two Ms may be the same or different. n is an integer of 2 or more, and 2 is preferred. 【0020】 The etheric oxygen atom contained in the n+1 valent perfluorohydrocarbon group may be located at the terminal end of the perfluorohydrocarbon group or between carbon atoms. The number of carbon atoms in the n+1 valent perfluorohydrocarbon group is preferably 1 or more, particularly preferably 2 or more, preferably 20 or less, and particularly preferably 10 or less. 【0021】 As L, an n+1 valent perfluoroaliphatic hydrocarbon group which may contain an etheric oxygen atom is preferred. 【0022】 The unit represented by formula (1) is preferably the unit represented by formula (1-3) or the unit represented by formula (1-4), and more preferably the unit represented by formula (1-3). 【0023】 【0024】 【0025】 R ｆ１ This is a perfluoroalkylene group which may contain oxygen atoms between carbon atoms. The number of carbon atoms in the above perfluoroalkylene group is preferably 1 or more, particularly preferably 2 or more, preferably 20 or less, and particularly preferably 10 or less. 【0026】 R ｆ２ This is a perfluoroalkylene group which may contain single bonds or oxygen atoms between carbon atoms. The number of carbon atoms in the above perfluoroalkylene group is preferably 1 or more, particularly preferably 2 or more, preferably 20 or less, and particularly preferably 10 or less. 【0027】 R ｆ３ This is a perfluoroalkylene group which may contain single bonds or oxygen atoms between carbon atoms. The number of carbon atoms in the above perfluoroalkylene group is preferably 1 or more, particularly preferably 2 or more, preferably 20 or less, and particularly preferably 10 or less. 【0028】 r is 0 or 1. m is 0 or 1. M is as described above. 【0029】 The unit represented by formula (1-3-1) is preferred over the unit represented by formula (1-3-3). The definition of M in the formula is as described above. 【0030】 【0031】 R ｆ４ R is a linear perfluoroalkylene group having 1 to 6 carbon atoms. ｆ５ This is a linear perfluoroalkylene group having 1 to 6 carbon atoms, which may contain single bonds or oxygen atoms between carbon atoms. The definitions of r and M are as described above. 【0032】 The following are specific examples of units represented by equation (1-3-1): 【0033】 【0034】The unit represented by formula (1-4) is preferably the unit represented by formula (1-4-1). ｆ１ , R ｆ２ The definition of M is as described above. 【0035】 【0036】 The following are specific examples of units represented by equation (1-4-1): 【0037】 【0038】 Units having two or more ion exchange groups may be used individually or in combination of two or more types. The content of units having two or more ion exchange groups in the fluorine-containing polymer (I) 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 (I). The content of units having two or more ion exchange groups in the fluorine-containing polymer (I) is preferably 14 mol% or less, more preferably 13 mol% or less, even more preferably 12.5 mol% or less, and particularly preferably 12 mol% or less, relative to the total units in the fluorine-containing polymer (I). The content of units having two or more ion exchange groups in the fluorine-containing polymer (I) is preferably 5 to 14 mol%, and more preferably 7 to 12.5 mol%. 【0039】The fluorine-containing polymer (I) preferably contains units based on fluorine-containing olefins. 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. Among these, TFE is preferred in terms of monomer production cost, reactivity with other monomers, and the excellent properties of the resulting fluorine-containing polymer (I). One type of fluorine-containing olefin may be used alone, or two or more types may be used in combination. The content of units based on fluorine-containing olefins in the fluorine-containing polymer (I) is preferably 86 mol% or more, more preferably 87 mol% or more, relative to the total units in the fluorine-containing polymer (I). The content of units based on fluorine-containing olefins in the fluorine-containing polymer (I) 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 (I). In the fluorine-containing polymer (I), the content of units based on fluorine-containing olefins is preferably 86 to 95 mol%, more preferably 87 to 93 mol%, and even more preferably 86 to 92 mol%, relative to the total units in the fluorine-containing polymer (I). 【0040】 The fluorine-containing polymer (I) may contain units having two or more ion-exchange groups, and units based on other monomers other than those based on fluorine-containing olefins. Specific examples of other monomers include CF ２ = CF - OR ｆ７ (However, R ｆ７ (These are perfluoroalkyl groups having 1 to 10 carbon atoms.) CF ２ = CFO (CF ２ ) ｖ CF = CF ２(where v is an integer of 1 to 3). Other monomer-based units are preferably 10 mol% or less, more preferably 1 mol% or less, still more preferably 0.1 mol% or less, and particularly preferably 0 mol% with respect to all the units in the fluorine-containing polymer (I) from the viewpoint of maintaining ion exchange performance. 【0041】 In the fluorine-containing polymer (I), the total content of units having two or more ion exchange groups and units based on fluorine-containing olefins is preferably 90 mol% or more, more preferably 99 mol% or more, particularly preferably 99.9 mol% or more, and most preferably 100 mol% with respect to all the units in the fluorine-containing polymer (I). 【0042】 The fluorine-containing polymer (I) preferably substantially does not contain units having only one ion exchange group. Examples of units having only one ion exchange group include units represented by the following formula (1-1) and units represented by the following formula (1-2). That the fluorine-containing polymer (I) substantially does not contain units having only one ion exchange group means that the content of units having only one ion exchange group is 0.1 mol% or less with respect to all the units in the fluorine-containing polymer (I), preferably 0.01 mol% or less, and more preferably 0 mol%. Formula (1-1) -[CF ２ -CF(-O-R ｆ１ -SO ３ M)]- Formula (1-2) -[CF ２ -CF(-R ｆ１ -SO ３ M)]- R ｆ１ and M are as defined above. 【0043】 <Infrared spectroscopic measurement> As described above, in the infrared spectrum obtained by measuring the fluorine-containing polymer (I) by infrared spectroscopy, the ratio (I －１ / I ２３５０ ) of the maximum absorbance I －１ at 1690 ± 10 cm １６９０ to the maximum absorbance I １６９０ at 2350 ± 30 cm ２３５０ is 0.150 or less. Hereinafter, the above I １６９０ / I ２３５０The calculation method will be described. 【0044】 First, a measurement film made of a fluorine-containing polymer (I) to be measured with a thickness of 50 to 150 μm is obtained. When the electrolyte membrane is made of the fluorine-containing polymer (I), the electrolyte membrane may be used as the measurement film. Next, prior to the measurement, the measurement film is immersed in a 2.5 mass% potassium hydroxide aqueous solution at 20°C for 30 minutes to convert the sulfonic acid groups contained in the fluorine-containing polymer into K salts. Next, in order to reduce the influence of the adsorbed water of the film on the infrared spectrum, it is dried using a vacuum dryer or the like. Using the dried measurement film, measurement is performed by infrared spectroscopy to obtain an infrared spectrum. The detailed measurement method and analysis method are as shown in the examples in the latter part. Note that in the region of 2350 ± 30 cm －１ (in the range of 2320 to 2380 cm －１ ), the absorption peak observed is an absorption derived from CF stretching, and in the region of 1690 ± 10 cm －１ (in the range of 1680 to 1700 cm －１ ), it can be said that the absorption peak observed is an absorption derived from the COOK group. 【0045】 The I １６９０ / I ２３５０ of the fluorine-containing polymer of the electrolyte membrane is 0.150 or less, preferably 0.100 or less, more preferably 0.070 or less, and even more preferably 0.050 or less. The lower limit of the above I １６９０ / I ２３５０ is not particularly limited, but is often 0.003 or more. 【0046】 <Structure of the membrane> The electrolyte membrane may have a single-layer structure or a multilayer structure. In the case of a multilayer structure, for example, a mode in which a plurality of layers containing the fluorine-containing polymer (I) and having different ion exchange capacities are laminated can be mentioned. 【0047】The fluorine-containing polymer (I) used in the electrolyte membrane may be of one type, or two or more types may be used in a laminated or mixed form. The electrolyte membrane may contain polymers other than fluorine-containing polymer (I), but it is preferable that the polymers in the electrolyte membrane consist substantially of fluorine-containing polymer (I). "Substantially consisting of fluorine-containing polymer (I)" means that the content of fluorine-containing polymer (I) is 95% by mass or more of the total mass of polymers in the electrolyte membrane. An upper limit for the content of fluorine-containing polymer (I) is 100% by mass of the total mass of polymers in the electrolyte membrane. Specific examples of polymers other than fluorine-containing polymer (I) include one or more polyazole compounds selected from the group consisting of polymers of heterocyclic compounds containing one or more nitrogen atoms in the ring, and polymers of heterocyclic compounds containing one or more nitrogen atoms and oxygen and / or sulfur atoms in the ring. Specific examples of polyazole compounds include polyimidazole compounds, polybenzimidazole compounds, polybenzobisimidazole compounds, polybenzoxazole compounds, polyoxazole compounds, polythiazole compounds, and polybenzothiazole compounds. In addition, from the standpoint of oxidation resistance of the electrolyte membrane, other polymers such as polyphenylene sulfide resins and polyphenylene ether resins can also be mentioned. 【0048】 From the viewpoint of further improving the durability during electrolysis, the electrolyte membrane preferably has a fluoride ion elution amount of 0.02% by mass or less, and more preferably 0.01% by mass or less, relative to the total mass of fluorine atoms in the electrolyte membrane. The Fenton test is measured by the method described in the examples below. The mass of fluorine atoms in the electrolyte membrane can be calculated based on elemental analysis of the electrolyte membrane, or, if the electrolyte membrane does not contain fluorine atom-containing compounds other than fluorine-containing polymer (I), based on the composition of the fluorine-containing polymer (I) contained in the electrolyte membrane. 【0049】<Reinforcement Material> The electrolyte membrane may be reinforced with a reinforcement material. Examples of reinforcement materials include porous materials, fibers, woven fabrics, and nonwoven fabrics. Examples of materials for the reinforcement material include polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer, polyethylene, polypropylene, polyphenylene sulfide, and polyether ether ketone. 【0050】 <Platinum-containing materials> The electrolyte membrane 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. Specific examples of platinum-containing composite oxides include 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. 【0051】 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. 【0052】 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. 【0053】 <Cerium-containing material> The 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 ２ O 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. 【0054】 <Film Thickness (Film Thickness When Dry)> The film thickness of the electrolyte membrane is preferably 20 μm or more, more preferably 40 μm or more, even more preferably 50 μm or more, particularly preferably 60 μm or more, and most preferably 70 μm or more. The film thickness of the electrolyte membrane is preferably 200 μm or less, more preferably 150 μm or less, even more preferably 130 μm or less, and particularly preferably 100 μm or less, from the viewpoint of being able to further reduce the electrolysis voltage when applied to an electrolytic device. The film thickness of the electrolyte membrane is preferably 20 to 200 μm, more preferably 50 to 150 μm, even more preferably 60 to 130 μm, and particularly preferably 70 to 100 μm, from the viewpoint of applicability to water electrolysis. The film thickness of the electrolyte membrane is measured by the method described in the examples below. 【0055】 [Method for Manufacturing Electrolyte Membranes] One example of a method for manufacturing electrolyte membranes is to produce a membrane (hereinafter also called a "precursor membrane") containing a polymer of a fluorine-containing monomer (hereinafter also called a "fluorine-containing monomer (I')") having two or more groups that can be converted into ion exchange groups (hereinafter also called a "fluorine-containing polymer (I')"), and then to produce the membrane by converting the groups in the precursor membrane that can be converted into ion exchange groups into ion exchange groups. 【0056】 Specific examples of groups in a fluorinated polymer (I') 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. Groups that can be converted to sulfonic acid-type functional groups are preferred because they can further reduce the electrolysis voltage when an electrolyte membrane is applied to a water electrolysis device. Examples of monomers having two or more groups that can be converted to ion exchange groups include CF ２ = A monomer containing a group represented by CF-O- (i.e., perfluorovinyl ether), or CF ２ = CF - CF ２A monomer containing a group represented by -O- (i.e., perfluoroallyl ether) is preferred, and CF is preferred because it exhibits superior effects in this disclosure. ２ A monomer containing a group represented as =CF-O- is more preferable. 【0057】 As the fluorine-containing polymer (I'), a polymer of a fluorine-containing monomer having two or more groups that can be converted to sulfonic acid-type functional groups (hereinafter also referred to as "fluorine-containing polymer (S')") is preferred, and a copolymer polymer of a fluorine-containing olefin and a monomer having two or more groups that can be converted to sulfonic acid-type functional groups and a fluorine atom is particularly preferred. The fluorine-containing polymer (S') will be described in detail below. 【0058】 Methods for copolymerizing fluorine-containing polymers (S') can include known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. 【0059】 Examples of fluorinated olefins include those exemplified above, and TFE is preferred due to its superior monomer production cost, reactivity with other monomers, and the characteristics of the resulting fluorinated polymer (I). Fluorinated olefins may be used individually or in combination of two or more. The content of units based on fluorinated olefins in fluorinated polymer (I') is preferably 86 mol% or more, and more preferably 87 mol% or more, relative to the total units in fluorinated polymer (I'). The content of units based on fluorinated olefins in fluorinated polymer (I') 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 fluorinated polymer (I'). 【0060】 Examples of fluorine-containing monomers (S') include compounds having one or more fluorine atoms in the molecule, having an ethylenically active double bond, and having two or more groups that can be converted to sulfonic acid-type functional groups. As a fluorine-containing monomer (S'), the compound represented by formula (2) is preferred due to its superior manufacturing cost, reactivity with other monomers, and the characteristics of the resulting fluorine-containing polymer (S). Formula (2) CF ２ =CF - L - (A)ｎ The definitions of L and n in formula (2) are as described above. A is a group that can be converted to a sulfonic acid type functional group. The group that can be converted to a sulfonic acid type functional group is preferably a functional group that can be converted to a sulfonic acid type functional group by hydrolysis. A specific example of a group that can be converted to a sulfonic acid type functional group is -SO ２ F, -SO ２ Cl, -SO ２ Br is one example. The n distinct A's may be the same or they may be different. 【0061】 The compound represented by formula (2) is preferably the compound represented by formula (2-3) or the compound represented by formula (2-4), and more preferably the compound represented by formula (2-3). 【0062】 【0063】 R in the formula ｆ１ , R ｆ２ The definitions of r and A are as described above. 【0064】 R in the formula ｆ１ , R ｆ２ , R ｆ３ The definitions of r, m, and A are as described above. 【0065】 【0066】 R in the formula ｆ１ , R ｆ２ , R ｆ３ The definitions of r, m, and A are as described above. 【0067】 Of the compounds represented by formula (2-3), the compound represented by formula (2-3-1) is preferred. 【0068】 【0069】 R in the formula ｆ４ , R ｆ５ The definitions of r and A are as described above. 【0070】 Specific examples of compounds represented by formula (2-3-1) include the following: 【0071】 【0072】 Of the compounds represented by formula (2-4), the compound represented by formula (2-4-1) is preferred. 【0073】 【0074】 R in the formula ｆ１ , R ｆ２ The definition of A is as stated above. 【0075】 Specific examples of compounds represented by formula (2-4-1) include the following: 【0076】 【0077】 The fluorine-containing monomer (S') may be used alone or in combination of two or more types. The content of units having two or more groups that can be converted into ion exchange groups in the fluorine-containing polymer (I') 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 (I'). The content of units having two or more groups that can be converted into ion exchange groups in the fluorine-containing polymer (I') is preferably 14 mol% or less, and more preferably 13 mol% or less, relative to the total units in the fluorine-containing polymer (I'). 【0078】 In the production of fluorine-containing polymer (S'), other monomers may be used in addition to fluorine-containing olefins and fluorine-containing monomers (S'). Examples of other monomers include those exemplified above. From the viewpoint of maintaining ion exchange performance, the content of units based on other monomers in fluorine-containing polymer (I') is preferably 10 mol% or less, more preferably 1 mol% or less, even more preferably 0.1 mol% or less, and particularly preferably 0 mol% relative to the total units in fluorine-containing polymer (I'). 【0079】It is preferable that the fluorine-containing polymer (I') substantially does not contain units having only one ion-exchange group. Examples of units having only one ion-exchange group include the unit represented by the following formula (1-1) and the unit represented by the following formula (1-2). When we say that the fluorine-containing polymer (I) substantially does not contain units having only one ion-exchange group, we mean that the content of units having only one ion-exchange group relative to the total units in the fluorine-containing polymer (I) is 0.1 mol% or less, preferably 0.01 mol% or less, and more preferably 0 mol%. 【0080】 The TQ value of the fluorine-containing polymer (I') is preferably 200°C or higher, more preferably 230°C or higher, and even more preferably 250°C or higher. Furthermore, the TQ value of the fluorine-containing polymer (I') is preferably 350°C or lower, more preferably 300°C or lower, even more preferably 290°C, and particularly preferably 280°C or lower. The TQ value of the fluorine-containing polymer (I') is preferably 200 to 350°C, more preferably 230 to 300°C, and even more preferably 250 to 290°C. The TQ value is a value related to the molecular weight of the polymer, and the volumetric flow rate is 100 mm. ３ This is expressed as temperature per second and is determined by the method described in the Examples section below. 【0081】 It is preferable to perform a fluorination treatment on the fluorine-containing polymer (I') used in the manufacture of electrolyte membranes. A preferred fluorination treatment is contact with a gas containing fluorine gas. When the fluorination treatment is performed, the ratio (I') described above is obtained. １６９０ / I ２３５０ ) makes it easier to obtain an electrolyte membrane with the above range. 【0082】The gas used in the fluorination treatment may contain gases other than fluorine gas. Examples of gases other than fluorine gas include inert gases, such as nitrogen gas and argon gas. The fluorine gas content in the gas used in the fluorination treatment is preferably 5% by volume or more, more preferably 10% by volume or more, and even more preferably 15% by volume or more. Furthermore, the fluorine gas content in the gas used in the fluorination treatment is preferably 40% by volume or less, more preferably 35% by volume or less, even more preferably 30% by volume or less, and particularly preferably 25% by volume or less. The fluorine gas content in the gas used in the fluorination treatment is preferably 5 to 40% by volume, more preferably 10 to 35% by volume, even more preferably 15 to 30% by volume, and particularly preferably 15 to 25% by volume. 【0083】 The atmospheric pressure during fluorination treatment is often -0.02 MPa or higher, and preferably 0.1 MPa or higher, as measured by gauge pressure (differential pressure relative to ambient pressure). Furthermore, the atmospheric pressure during fluorination treatment is preferably 1.0 MPa or lower, preferably 0.5 MPa or lower, and more preferably 0.3 MPa or lower, as measured by gauge pressure. A positive gauge pressure indicates a pressure higher than the ambient pressure. 【0084】 The temperature at which the fluorination treatment is carried out is preferably 150°C or higher, more preferably 160°C or higher, and even more preferably 170°C or higher. The temperature at which the fluorination treatment is carried out is preferably 250°C or lower, more preferably 220°C or lower. The temperature at which the above fluorination treatment is preferably 150 to 250°C, more preferably 160 to 220°C, and even more preferably 170 to 220°C. The time at which the fluorination treatment is carried out is preferably 0.1 hours or more, more preferably 1 hour or more, and even more preferably 3 hours or more. Furthermore, the time at which the fluorination treatment is carried out is preferably 24 hours or less, more preferably 12 hours or less, and even more preferably 7 hours or less. The time at which the above fluorination treatment is preferably 0.1 to 24 hours, more preferably 1 to 12 hours, even more preferably 1 to 7 hours, and particularly preferably 3 to 7 hours. 【0085】Furthermore, it is preferable to perform vacuum drying of the fluorine-containing polymer (I') before the fluorination treatment described above. The pressure used for vacuum drying is preferably 0.02 MPa or less in absolute pressure, and more preferably 0.01 MPa or less. The temperature used for vacuum drying is preferably 50°C or higher, and more preferably 80°C or higher. In addition, the temperature used for vacuum drying is preferably 300°C or lower, and more preferably 250°C or lower. 【0086】 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. 【0087】 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. 【0088】 Specific examples of methods for converting groups in a precursor film that can be converted into ion exchange groups include methods of treating the precursor film with hydrolysis or acidification. For hydrolysis, a method of contacting the precursor film with an alkaline aqueous solution is preferred. 【0089】 Specific examples of methods for bringing a 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. 【0090】The alkaline aqueous solution preferably contains an alkali metal hydroxide, a water-soluble organic solvent, and water. Examples of alkali metal hydroxides include sodium hydroxide and potassium hydroxide. In this specification, a water-soluble organic solvent is an organic solvent that dissolves readily in water, and specifically, an organic solvent with a solubility of 0.1 g or more in 1,000 ml of water (20°C) is preferred, and an organic solvent with a solubility of 0.5 g or more is more preferred. The water-soluble organic solvent preferably contains at least one selected from the group consisting of aprotic organic solvents, alcohols, and amino alcohols, and more preferably contains an aprotic organic solvent. The water-soluble organic solvent may be used alone or in combination of two or more. 【0091】 Specific examples of aprotic organic solvents include dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone, with dimethyl sulfoxide being preferred. Specific examples of alcohols include methanol, ethanol, isopropanol, butanol, methoxyethoxyethanol, butoxyethanol, butylcarbitol, hexyloxyethanol, octanol, 1-methoxy-2-propanol, and ethylene glycol. Specific examples of amino alcohols include ethanolamine, N-methylethanolamine, N-ethylethanolamine, 1-amino-2-propanol, 1-amino-3-propanol, 2-aminoethoxyethanol, 2-aminothioethoxyethanol, and 2-amino-2-methyl-1-propanol. 【0092】 The concentration of alkali metal hydroxide is preferably 1 to 60% by mass, and more preferably 3 to 55% by mass, in the alkaline aqueous solution. The content of water-soluble organic solvent is preferably 1 to 60% by mass, and more preferably 3 to 55% by mass, in the alkaline aqueous solution. The concentration of water is preferably 39 to 80% by mass, in the alkaline aqueous solution. 【0093】 The hydrolysis temperature is preferably 0 to 120°C, more preferably 60 to 110°C, and even more preferably 90 to 100°C. 【0094】After contact between the precursor film and the alkaline aqueous solution, a treatment to remove the alkaline aqueous solution may be performed. One method for removing the alkaline aqueous solution is to wash the precursor film that has been in contact with the alkaline aqueous solution with water. 【0095】 After contacting the precursor film with an alkaline aqueous solution, the resulting film may be contacted with an acidic aqueous solution to convert the ion exchange groups to the acidic form. Specific examples of methods for contacting the precursor film with an acidic aqueous solution include immersing the precursor film in the acidic aqueous solution and spraying the acidic aqueous solution onto the surface of the precursor film. The acidic aqueous solution preferably contains an acid component and water. Specific examples of the acid component include hydrochloric acid and sulfuric acid. 【0096】 Although the above-described method for manufacturing an electrolyte membrane was explained using the example of an electrolyte membrane that does not contain a reinforcing material, the method is not limited to this, and an electrolyte membrane may be manufactured using a reinforcing material. When a reinforcing material is used, for example, a method of joining the precursor membrane or electrolyte membrane and the reinforcing material by heat pressing or melt lamination may be used. 【0097】 Although a method for manufacturing an electrolyte membrane according to one embodiment of the present invention has been described above, the invention is not limited thereto, and may be manufactured by, for example, a casting method (a method of manufacturing an electrolyte membrane by applying an aqueous dispersion containing a fluorine-containing polymer (I) to a substrate, drying it, and peeling off the substrate). However, from the viewpoint of the effects of the present invention, the melt extrusion or hot press molding described above is preferred. 【0098】 [Electrolyte membrane with catalyst layer and membrane electrode assembly] An electrolyte membrane with a catalyst layer manufactured using the electrolyte membrane of this disclosure includes an anode catalyst layer, a cathode catalyst layer, and an electrolyte membrane disposed between the anode catalyst layer and the cathode catalyst layer. The membrane electrode assembly of this disclosure includes an anode having a catalyst layer, a cathode having a catalyst layer, and an electrolyte membrane disposed between the anode and the cathode. The electrolyte membrane is as described above, so its explanation is omitted. 【0099】Figure 1 is a cross-sectional view showing an example of a membrane electrode assembly of the present disclosure. The membrane electrode assembly 20 includes an anode 22 having a catalyst layer 26 and a gas diffusion layer 28, a cathode 24 having a catalyst layer 26 and a gas diffusion layer 28, and an electrolyte membrane 10 disposed between the anode 22 and the cathode 24 in contact with the catalyst layer 26. In Figure 1, the laminate of the catalyst layer 26 of the anode 22, the electrolyte membrane 10, and the catalyst layer 26 of the cathode 24 is the electrolyte membrane with a catalyst layer. 【0100】 <Anode and Cathode> The anode and cathode each have a catalyst layer. In the example in Figure 1, the anode 22 and cathode 24 each have a catalyst layer 26 and a gas diffusion layer 28. In at least one of the anode 22 and cathode 24, there may be a region where a portion of the gas diffusion layer 28 and the catalyst layer 26 overlap in the thickness direction. In addition, in at least one of the anode 22 and cathode 24, the catalyst layer 26 may be omitted, and the gas diffusion layer 28 may perform the role of the catalyst layer 26. 【0101】 Specific examples of catalyst layers include layers containing a catalyst and a polymer having ion exchange groups. Specific examples of catalysts include supported catalysts in which a catalyst containing platinum, a platinum alloy, or platinum having a core-shell structure is supported on a carbon support, ruthenium oxide catalysts, iridium oxide catalysts, ruthenium-containing composite oxides, iridium-containing composite oxides, catalysts containing ruthenium oxide having a core-shell structure, and catalysts containing iridium oxide having a core-shell structure. Carbon black powder can be used as the carbon support. The polymer having ion exchange groups is not particularly limited, and for example, known fluorine-containing polymers having ion exchange groups can be used. The catalyst included in the anode-side catalyst layer is preferably one or more catalysts selected from the group consisting of ruthenium oxide catalysts, iridium oxide catalysts, ruthenium-containing composite oxides, iridium-containing composite oxides, catalysts containing ruthenium oxide having a core-shell structure, and catalysts containing iridium oxide having a core-shell structure. The supported catalyst is preferred as the catalyst included in the cathode-side catalyst layer. 【0102】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. For the gas diffusion layer on the anode side, a metal mesh is preferably used. 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. In the film electrode assembly shown in Figure 1, the gas diffusion layer 28 is included, but the gas diffusion layer is an arbitrary component and does not have to be included in the film electrode assembly. Furthermore, as described above, the gas diffusion layer may contain the catalyst mentioned above. 【0103】 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 is measured using an image obtained by measuring a cross-section of the film electrode assembly cut in a plane parallel to the film thickness direction with an optical microscope, and is the arithmetic mean value at any 20 locations. 【0104】[Method for Manufacturing a Membrane Electrode Assembly] Examples of methods for manufacturing a membrane electrode assembly include forming a catalyst layer on an electrolyte membrane and then sandwiching the resulting assembly with a gas diffusion layer, and forming a catalyst layer on a gas diffusion layer to form electrodes (anode, cathode) and then sandwiching the electrolyte membrane with these electrodes. Methods for manufacturing the catalyst layer include applying a catalyst layer forming coating solution to a predetermined position on the electrolyte membrane and drying it as needed. Alternatively, a catalyst layer forming coating solution may be applied to a substrate and dried to form the catalyst layer on the substrate, after which the formed catalyst layer is transferred to the electrolyte membrane. The catalyst layer forming coating solution may be a liquid in which a polymer having ion exchange groups and a catalyst are dispersed in a dispersion medium. After the catalyst layer is formed, it is preferable to heat and pressurize the laminate containing the catalyst layer from the viewpoint of hydrogen permeability. The heating temperature is preferably between 130°C and 180°C. When pressurization is performed using a flat plate press, the surface pressure is preferably 0.2 MPa or higher, more preferably 1.0 MPa or higher, even more preferably 1.5 MPa or higher, and particularly preferably 2.0 MPa or higher. Furthermore, the surface pressure is preferably 30.0 MPa or lower, more preferably 10.0 MPa or lower, and even more preferably less than 3.0 MPa. When pressurization is performed using a roll press, the linear pressure is preferably 3 kg / cm or higher, and also preferably 200 kg / cm or lower. 【0105】 <Applications> The membrane electrode assembly of this disclosure can be used in a water electrolysis apparatus (specifically, a polymer electrolyte water electrolysis apparatus). 【0106】[Water Electrolyzer] The water electrolyzer of the present disclosure includes the membrane electrode assembly described above. Because the water electrolyzer of the present disclosure includes the membrane electrode assembly described above (the electrolyte membrane of the present disclosure), it has excellent durability during electrolysis. Furthermore, because it has excellent proton conductivity, the electrolysis voltage during electrolysis tends to be low. The water electrolyzer of the present disclosure can have the same configuration as known water electrolyzers, except that it includes the membrane electrode assembly described above. For example, the water electrolyzer of the present disclosure has a water supply unit that supplies water to the anode catalyst layer side and a power supply unit that is electrically connected to the anode catalyst layer side and the cathode catalyst layer side. In the water electrolyzer of the present disclosure, when a DC voltage is applied by the power supply unit while water is supplied to the anode catalyst layer side by the water supply unit, water decomposes on the anode catalyst layer side, generating oxygen and protons. On the cathode catalyst layer side, protons that have moved to the cathode catalyst layer side via the electrolyte membrane gain electrons, generating hydrogen. The water electrolyzer of the present disclosure may also have an oxygen recovery member for recovering the generated oxygen and a hydrogen recovery member for recovering the generated hydrogen. 【0107】 The water electrolysis apparatus disclosed herein provides a flow rate of 2 A / cm² when water is electrolyzed. ２ The hydrogen permeability coefficient in is 2.8 × 10⁻⁶. －６ cc・cm / cm ２ It is preferable that it be sec·atm or less, and 2.0 × 10 －６ cc・cm / cm ２ It is more preferable that the hydrogen permeability coefficient is 0.1 × 10⁻¹⁰. －６ cc・cm / cm ２ - It is often sec·atm or higher. Because the water electrolysis apparatus of this disclosure includes the electrolyte membrane of this disclosure, it is thought that the outflow of fluoride ions is reduced, the hydrogen permeability coefficient during water electrolysis is lower, and the durability during electrolysis is improved. The hydrogen permeability coefficient is determined by the method described in the Examples section below. 【0108】 [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. 【0109】 The present invention will be described in detail below with reference to examples. Examples 1 to 3 and 9 are examples, and Examples 4 to 8 and 10 are comparative examples. However, the present invention is not limited to these examples. 【0110】 [Measurement method] 【0111】 <Proportion of each unit> The proportion of each unit in the fluorine-containing polymer was calculated from the ion exchange capacity measurement results described later, and the amount of each monomer used in the production of the polymer. 【0112】 <Ion exchange capacity of fluorine-containing polymers> After weighing the fluorine-containing polymer after vacuum drying, it is placed in a polycarbonate container and subjected to a 0.7 mol / L NaOH solution (solvent: H2). 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. ２ The 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. 【0113】 <Infrared Spectroscopy Measurement> Using the electrolyte membrane obtained in the subsequent procedure as the measurement sample, infrared spectroscopy was performed according to the procedure described above. In the obtained infrared spectrum, the infrared spectrum at 2350 ± 30 cm⁻¹ was observed. －１ Maximum absorbance I ２３５０ 1690 ± 10 cm －１ Maximum absorbance I １６９０ The ratio (I １６９０ / I ２３５０ The following was calculated: For infrared spectroscopy, a Nicolet iS20 FT-IR spectrophotometer manufactured by Thermo Fisher Scientific was used. The measurement conditions were 32 integration cycles and a resolution of 4 cm. －１ That's what I decided. 【0114】 From the obtained infrared spectrum, the maximum absorbance I ２３５０The following procedure was used to calculate the value: 2350 ± 30 cm⁻¹ of the infrared spectrum. －１ Absorption in the vicinity is often relatively broad. Therefore, in this specification, 2740 ± 20 cm －１ The point showing the minimum absorbance within the range, and 2070 ± 20 cm －１ The baseline is defined as the line connecting the point showing the minimum absorbance within the range, and from the baseline, 2350 ± 30 cm －１ The difference between the points showing the highest absorbance within the range is the maximum absorbance I. ２３５０ That's what I decided. 【0115】 Furthermore, from the obtained infrared spectrum, the maximum absorbance I １６９０ The following procedure was used to calculate the value: First, the measured wavefrequency was 1690 ± 10 cm. －１ At the absorption peak, 1690 cm －１ It is closest to and 1690 cm －１ The point at the wavelength that shows a minimum value on the high wavenumber side, and 1690 cm －１ It is closest to and 1690 cm －１ The baseline was defined as a straight line connecting points at wavelengths showing minimum values ​​on the low wavenumber side. From the above baseline, 1690 ± 10 cm －１ The difference between the points showing the maximum absorbance within the range is called the maximum absorbance I. １６９０ That's what I decided. 【0116】 <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. 【0117】<Film Thickness of Electrolyte Membrane During Drying> 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 (Mitutoyo Corporation) with a flat terminal with a diameter of 5 mm attached to its tip. The arithmetic mean was taken as the film thickness of the electrolyte membrane during drying. Specifically, the electrolyte membrane obtained by the method described later in <Method for Manufacturing Electrolyte Membrane> was cut into a 7.0 cm x 7.0 cm square, and the film thickness was measured at nine points at equal intervals on the four sides and diagonals (nine points placed at 2 cm intervals with a reference point 0.5 mm inward from each side). The arithmetic mean of these nine points was taken as the film thickness of the electrolyte membrane during drying. 【0118】 <Hydrogen Permeation Coefficient during Water Electrolysis> The hydrogen concentration in the gas at the anode of each membrane electrode assembly was measured according to the following procedure, and the hydrogen crossover was evaluated. First, a membrane electrode assembly 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, resulting in an electrode area of ​​16 cm². ２ A membrane electrode assembly was incorporated into the single cell. When the membrane electrode assembly was clamped, it was fastened so that a pressure of 1.3 MPa was applied to the electrode portion. Next, in order to sufficiently hydrate the electrolyte membrane and the fluorine-containing polymer of both electrodes, pure water with a conductivity of 1.0 μS / cm or less, 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. After that, pure water with a conductivity of 1.0 μS / cm or less, a temperature of 80°C was supplied to the anode side at a flow rate of 50 mL / min, and while the back pressure was kept at atmospheric pressure for 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, a 4-hour water electrolysis was performed as a break-in period. Subsequently, 0-48A (current density 0-3A / cm²) was used. ２IV (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 gas was held at the specified current for 4 hours. After the holding time for each current, water was separated from the gas discharged from the anode side. The hydrogen concentration in the gas on the anode side was then measured using a micro GC (Agilent 490, manufactured by Agilent Corporation), and the hydrogen concentration in the gas at the final measurement point (volume %) was measured (hydrogen content / gas content). From the current and gas concentration at the time of measurement, the amount of hydrogen permeating from the cathode side to the anode side was calculated, and by multiplying this by the film thickness during drying, the result was obtained as 2 A / cm². ２ The hydrogen permeability coefficient of the electrolyte membrane during water electrolysis was calculated at the given current density. Based on the calculated hydrogen permeability coefficient, evaluation was performed according to the following criteria: A: 2 A / cm ２ The hydrogen permeability coefficient in is 2.0 × 10 －６ Below B: 2A / cm ２ The hydrogen permeability coefficient in is 2.0 × 10 －６ Super 2.8×10 －６ Below C: 2A / cm ２ The hydrogen permeability coefficient in is 2.8 × 10 －６ Furthermore, the unit of hydrogen permeability coefficient is "cc・cm / cm" ２ It is "sec.atm". 【0119】<Fenton Test> For each example, the electrolyte membrane was cut to approximately 2.5 cm x 2.5 cm and held in a glove box with nitrogen gas flowing through it for 24 hours. Approximately 0.1 g was weighed in the glove box. Then, the electrolyte membrane was immersed in 50 g of Fenton's reagent containing 3% by mass of hydrogen peroxide and 200 ppm of divalent iron ions at 40°C for 16 hours. After removing the electrolyte membrane after immersion, the mass of the Fenton's reagent was measured, the fluoride ion concentration in the Fenton's reagent was measured with an ion meter, and the amount of fluoride ions eluted relative to the total mass of fluorine atoms in the immersed electrolyte membrane was calculated. A ＋ A: Fluoride ion elution amount is 0.007% by mass or less B: Fluoride ion elution amount is greater than 0.007% by mass but 0.010% by mass or less C: Fluoride ion elution amount is greater than 0.010% by mass but 0.020% by mass or less 【0120】 <Fluorine Release Rate> The fluoride ion concentration in the water discharged from the cathode side of each membrane electrode assembly was measured according to the following procedure, and the fluorine release rate was evaluated. First, a break-in operation was performed in the same manner as the measurement method for the hydrogen permeability coefficient during water electrolysis described above. Then, the water supply rate to the anode catalyst layer was changed to 150 mL / min, and the back pressure was changed to 50 kPa for both the anode and cathode, resulting in a current density of 2 A / cm². ２ The system was operated for 500 hours. Between 300 and 500 hours after the break-in period, wastewater discharged from the cathode catalyst layer was sampled. The amount of fluoride ions contained in this wastewater was quantified by ion chromatography and averaged to calculate the average amount of fluoride ions per unit electrode area and per unit time, and evaluated as the fluorine release rate according to the following criteria. A smaller fluorine release rate indicates that the decomposition of the fluorine-containing polymer is suppressed and the electrolyte membrane has superior durability during electrolysis. In practical terms, an A or B rating is preferable, with an A rating being more preferable. A: 1.0 × 10 －６ mg / (h·cm) ２ ) Less than B: 1.0 × 10 －６ mg / (h·cm) ２ ) Above, 3.0 x 10 －６ mg / (h·cm) ２) Less than C: 3.0 x 10 －６ mg / (h·cm) ２ ) That's all. 【0121】 <Conductivity> A substrate with four-terminal electrodes arranged at 5 mm intervals was placed in close contact with a 5 mm wide electrolyte membrane. The resistance of the electrolyte membrane H was measured using a known four-terminal method under constant temperature and humidity conditions of 80°C and 50% relative humidity, with AC: 10 kHz and voltage: 1 V, and the conductivity was calculated. The standard dimensions and thickness of the membrane used in the calculation were measured under conditions of 23°C and 50% relative humidity RH. Based on the calculated conductivity, the conductivity was evaluated according to the following criteria. The measured conductivity can be considered an indicator of proton conductivity. For practical purposes, an A or B evaluation is preferred for conductivity (proton conductivity), with an A evaluation being more preferred. A: Conductivity of 0.1 S / cm or more B: Conductivity of 0.05 S / cm or more and less than 0.1 S / cm C: Conductivity of less than 0.05 S / cm 【0122】 [Abbreviations] The manufacturing procedures for the electrolyte membranes in each example are described below. The abbreviations used in the procedures for each example are as follows: 【0123】 <Monomers> ・TFE: Tetrafluoroethylene monomer m1: 【0124】 【0125】 Monomer m2: CF ２ = CFOCF ２ CF (CF ３ )O(CF ２ ) ２ SO ２ F 【0126】 【0127】 <Radical polymerization initiators> ・V-601: Dimethyl 2,2'-azobis (2-methylpropionate) ・AIBN: 2,2'-Azobis (isobutyrinitrile) 【0128】 <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 ２ CF ２ CHClF ・HCFC-141b:CH ３ CCl ２ F 【0129】[Production of Fluorine-Containing Polymer] <Fluorine-Containing Polymer F1> 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. The contents were then stirred at 142 rpm, the temperature was raised to 70°C, and TFE was introduced to bring the total pressure to 0.96 MPaG. Note that MPaG is the differential pressure (gauge pressure) from atmospheric pressure expressed in MPa. 332 g of HCFC-225cb solution containing 3.00 mass% AIBN was injected into the reactor under pressure to start polymerization. Thereafter, 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 liquid composition A1 was obtained, which is a solution in which the fluorine-containing polymer A1 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 A1 was transferred to another tank while being diluted. The diluted liquid composition was kept at 25°C and quantitatively added to 34.5 kg of HCFC-141b at 25°C, and stirred to agglomerate the fluorine-containing polymer A1 and form particles containing the fluorine-containing polymer A1. After stirring, the liquid containing the particles containing the fluorine-containing polymer A1 was filtered using a filter cloth. The separated and recovered particles containing fluorine-containing polymer A1 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 fluorine-containing polymer A1. The particles containing fluorine-containing polymer A1 were vacuum-dried at 90°C for 16 hours to obtain 2,189 g of fluorine-containing polymer A1. The ion exchange capacity of fluorine-containing polymer A1 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 fluorine-containing polymer A1 was 91 mol%, and the ratio of units based on TFE to units based on monomer m1 was 91:9 in molar ratio. 【0130】[Fluorination Treatment] 20.0 g of the fluorine-containing polymer A1 powder obtained by the above procedure was uniformly dispersed on a PFA petri dish in a nickel reactor and placed in the 1.1 L reactor. Then, a gas mixture of 20% fluorine gas and 80% nitrogen gas was introduced into the reactor at a gauge pressure of 0.15 MPa, and the reactor was maintained at 200°C for 4 hours to perform the fluorination treatment. After the treatment, the fluorine gas was exhausted, the polymer was removed, and it was pulverized in a pulverizer to obtain the fluorine-containing polymer F1. 【0131】 <Fluorine-containing polymer F2> In a 230 mL stainless steel reactor, 50.0 g of monomer m1, 80.6 g of HFC-52-13p, and 108 mg of CH ３OH was charged, and freeze-degassing was thoroughly carried out using liquid nitrogen. Then, the contents were stirred at 300 rpm, the temperature was raised to 70°C, TFE was introduced, and the total pressure was set to 0.82 MPaG. 3.08 g of an initiator solution, in which the radical polymerization initiator V-601 was dissolved in HFC-52-13p at a concentration of 2.63 mass%, 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 25.3 g, the reactor was cooled to 10°C, unreacted TFE was vented, and liquid composition A2, which is a solution in which the fluorine-containing polymer A2 is dissolved in unreacted monomer m1 and HFC-52-13p, was obtained. 146 g of liquid composition A2 was kept at 25°C and added to 378 g of HFE-347pc-f at -17°C. The mixture was stirred to agglomerate the fluorine-containing polymer A2 and form particles containing fluorine-containing polymer A2. After stirring, the liquid containing the particles containing fluorine-containing polymer A2 was filtered using filter paper. 150 g of HFE-347pc-f at 25°C was added to the separated and recovered particles containing fluorine-containing polymer A2, stirred, and then filtered to wash the mixture. The washing process was repeated a total of three times to obtain particles containing fluorine-containing polymer A2. The particles containing fluorine-containing polymer A2 were vacuum-dried at 240°C for 16 hours to obtain 37.7 g of fluorine-containing polymer A2. The ion exchange capacity and TQ value of the vacuum-dried fluorine-containing polymer A2 were measured according to the method described above. The ion exchange capacity was 1.02 meq / g, and the TQ value was 253°C. Furthermore, in fluorine-containing polymer A2, the content of units based on TFE relative to the total units contained in fluorine-containing polymer A2 was 93 mol%, and the ratio of units based on TFE to units based on monomer m1 was 93:7 in molar ratio. 【0132】 [Fluorination Treatment] 20.0 g of the fluorine-containing polymer A2 powder obtained by the above procedure was uniformly dispersed on a PFA petri dish in a nickel reactor and placed in a 1.1 L reactor. Then, a gas mixture of 20% fluorine gas and 80% nitrogen gas was introduced into the reactor at a gauge pressure of 0.15 MPa, and the reactor was maintained at 200°C for 4 hours to perform the fluorination treatment. After the treatment, the fluorine gas was exhausted, the polymer was removed, and it was pulverized in a pulverizer to obtain the fluorine-containing polymer F2. 【0133】 <Fluorine-containing polymer F3> 75.0 g of monomer m1 and 92.2 g of HFC-52-13p were charged into a 230 mL stainless steel reactor, and freeze-degassing was thoroughly carried out using liquid nitrogen. After that, the contents were heated to 70°C while stirring at 300 rpm, and then TFE was introduced to bring the total pressure to 0.71 MPaG. Next, V-601 was dissolved in HFC-52-13p at a concentration of 1.70 mass% to obtain an initiator solution, and 3.05 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 13.7 g, the reactor was cooled to 10°C, unreacted TFE was vented, and liquid composition A3, which is a solution in which fluorine-containing polymer A3 is dissolved in unreacted monomer m1 and HFC-52-13p, was obtained. 177 g of liquid composition A3 was kept at 25°C and added to 288 g of HFE-347pc-f at 25°C. The mixture was stirred to agglomerate the fluorine-containing polymer A3 and form particles containing fluorine-containing polymer A3. After stirring, the liquid containing the particles containing fluorine-containing polymer A3 was filtered using filter paper. The separated and recovered particles containing fluorine-containing polymer A3 were washed by adding 150 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 fluorine-containing polymer A3. The particles containing fluorine-containing polymer A3 were vacuum-dried at 240°C for 16 hours to obtain 23.9 g of fluorine-containing polymer A3. The ion exchange capacity of fluorine-containing polymer A3 was 1.45 meq / g, and the TQ value was 264°C. Furthermore, in fluorine-containing polymer A3, the content of units based on TFE relative to the total units contained in fluorine-containing polymer A3 was 88 mol%, and the ratio of units based on TFE to units based on monomer m1 was 88:12 in molar ratio. 【0134】[Fluorination Treatment] 20.0 g of the fluorine-containing polymer A3 powder obtained by the above procedure was uniformly dispersed on a PFA petri dish in a nickel reactor and placed in the 1.1 L reactor. Then, a mixture of 20% fluorine gas and 80% nitrogen gas was introduced into the reactor at a gauge pressure of 0.15 MPa, and the reactor was maintained at 200°C for 4 hours to perform the fluorination treatment. After the treatment, the fluorine gas was exhausted, the polymer was removed, and it was pulverized in a pulverizer to obtain the fluorine-containing polymer F3. 【0135】 <Fluorine-containing polymer F3'> [Fluorination treatment] 20.0 g of powder of fluorine-containing polymer A3 obtained by the above procedure was uniformly dispersed on a PFA petri dish in a nickel reactor and placed in a 1.1 L reactor. Then, a mixture of 20% fluorine gas and 80% nitrogen gas was introduced into the reactor at a gauge pressure of 0.15 MPa and the reactor was maintained at 150°C for 4 hours to perform the fluorination treatment. After the treatment, the fluorine gas was exhausted and the polymer was removed and pulverized in a pulverizer to obtain the fluorine-containing polymer F3'. 【0136】<Fluorine-containing polymer F4> 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. After that, the contents were heated to 65°C while stirring at 300 rpm, then TFE was introduced and the total pressure was set to 1.10 MPaG. Next, AIBN was dissolved in HFC-52-13p at a concentration of 2.58 mass% to obtain 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 liquid composition A4, which is a solution in which fluorine-containing polymer A4 is dissolved in unreacted monomer m1 and HFC-52-13p, was obtained. 134 g of liquid composition A4 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 A4 and form particles containing fluorine-containing polymer A4. After stirring, the liquid containing the particles containing fluorine-containing polymer A4 was filtered using filter paper. 154 g of HFE-347pc-f at 25°C was added to the separated and recovered particles containing fluorine-containing polymer A4, stirred, and then filtered to wash the mixture. The washing process was repeated a total of three times to obtain particles containing fluorine-containing polymer A4. The particles containing fluorine-containing polymer A4 were vacuum-dried at 240°C for 16 hours to obtain 22.3 g of fluorine-containing polymer A4. The ion exchange capacity of fluorine-containing polymer A4 was 1.68 meq / g, and the TQ value was 250°C. Furthermore, in fluorine-containing polymer A4, the content of units based on TFE relative to the total units contained in fluorine-containing polymer A4 was 85 mol%, and the ratio of units based on TFE to units based on monomer m1 was 85:15 in molar ratio. 【0137】[Fluorination Treatment] 20.0 g of the fluorine-containing polymer A4 powder obtained by the above procedure was uniformly dispersed on a PFA petri dish in a nickel reactor and placed in the 1.1 L reactor. Then, a mixture of 20% fluorine gas and 80% nitrogen gas was introduced into the reactor at a gauge pressure of 0.2 MPa, and the reactor was maintained at 200°C for 5 hours to perform the fluorination treatment. After the treatment, the fluorine gas was exhausted, the polymer was removed, and it was pulverized in a pulverizer to obtain the fluorine-containing polymer F4. 【0138】<Fluorine-containing polymer F4> 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. After that, the contents were heated to 65°C while stirring at 300 rpm, then TFE was introduced and the total pressure was set to 1.10 MPaG. Next, AIBN was dissolved in HFC-52-13p at a concentration of 2.58 mass% to obtain 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 liquid composition A4, which is a solution in which fluorine-containing polymer A4 is dissolved in unreacted monomer m1 and HFC-52-13p, was obtained. 134 g of liquid composition A4 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 A4 and form particles containing fluorine-containing polymer A4. After stirring, the liquid containing the particles containing fluorine-containing polymer A4 was filtered using filter paper. 154 g of HFE-347pc-f at 25°C was added to the separated and recovered particles containing fluorine-containing polymer A4, stirred, and then filtered to wash the mixture. The washing process was repeated a total of three times to obtain particles containing fluorine-containing polymer A4. The particles containing fluorine-containing polymer A4 were vacuum-dried at 240°C for 16 hours to obtain 22.3 g of fluorine-containing polymer A4. The ion exchange capacity of fluorine-containing polymer A4 was 1.68 meq / g, and the TQ value was 250°C. Furthermore, in fluorine-containing polymer A4, the content of units based on TFE relative to the total units contained in fluorine-containing polymer A4 was 85 mol%, and the ratio of units based on TFE to units based on monomer m1 was 85:15 in molar ratio. 【0139】[Fluorination Treatment] 20.0 g of the fluorine-containing polymer A4 powder obtained by the above procedure was uniformly dispersed on a PFA petri dish in a nickel reactor and placed in the 1.1 L reactor. Then, a mixture of 20% fluorine gas and 80% nitrogen gas was introduced into the reactor at a gauge pressure of 0.2 MPa, and the reactor was maintained at 200°C for 5 hours to perform the fluorination treatment. After the treatment, the fluorine gas was exhausted, the polymer was removed, and it was pulverized in a pulverizer to obtain the fluorine-containing polymer F4. 【0140】<Fluorine-containing polymer F4> 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. After that, the contents were heated to 65°C while stirring at 300 rpm, then TFE was introduced and the total pressure was set to 1.10 MPaG. Next, AIBN was dissolved in HFC-52-13p at a concentration of 2.58 mass% to obtain 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 liquid composition A4, which is a solution in which fluorine-containing polymer A4 is dissolved in unreacted monomer m1 and HFC-52-13p, was obtained. 134 g of liquid composition A4 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 A4 and form particles containing fluorine-containing polymer A4. After stirring, the liquid containing the particles containing fluorine-containing polymer A4 was filtered using filter paper. 154 g of HFE-347pc-f at 25°C was added to the separated and recovered particles containing fluorine-containing polymer A4, stirred, and then filtered to wash the mixture. The washing process was repeated a total of three times to obtain particles containing fluorine-containing polymer A4. The particles containing fluorine-containing polymer A4 were vacuum-dried at 240°C for 16 hours to obtain 22.3 g of fluorine-containing polymer A4. The ion exchange capacity of fluorine-containing polymer A4 was 1.68 meq / g, and the TQ value was 250°C. Furthermore, in fluorine-containing polymer A4, the content of units based on TFE relative to the total units contained in fluorine-containing polymer A4 was 85 mol%, and the ratio of units based on TFE to units based on monomer m1 was 85:15 in molar ratio. 【0141】[Fluorination Treatment] 20.0 g of the fluorine-containing polymer A4 powder obtained by the above procedure was uniformly dispersed on a PFA petri dish in a nickel reactor and placed in the 1.1 L reactor. Then, a mixture of 20% fluorine gas and 80% nitrogen gas was introduced into the reactor at a gauge pressure of 0.15 MPa, and the reactor was maintained at 200°C for 4 hours to perform the fluorination treatment. After the treatment, the fluorine gas was exhausted, the polymer was removed, and it was pulverized in a pulverizer to obtain the fluorine-containing polymer F4. 【0142】 <Fluorine-containing polymer F5> Fluorine-containing polymer A5 was manufactured with reference to the description in paragraph 0197 of Japanese Patent Application Publication No. 2015-099772. The ion exchange capacity of fluorine-containing polymer A5 was 1.25 meq / g, and the TQ value was 232°C. Furthermore, the content of units based on TFE relative to the total units contained in fluorine-containing polymer A5 was 78 mol%, and the ratio of units based on TFE to units based on monomer m2 was 78:22 in molar ratio. 【0143】 [Fluorination Treatment] 20 g of powder of fluorine-containing polymer A5 obtained by the above procedure was uniformly dispersed on a PFA petri dish in a nickel reactor and placed in the 1.1 L reactor. Then, a mixture of 20% fluorine gas and 80% nitrogen gas was introduced into the reactor at a gauge pressure of 0.2 MPa, and the reactor was maintained at 190°C for 5 hours to perform the fluorination treatment. After the treatment, the fluorine gas was exhausted, the polymer was removed, and it was pulverized in a pulverizer to obtain fluorine-containing polymer F5. 【0144】 <Fluorine-containing polymer F6> Fluorine-containing polymer A6 was manufactured with reference to the description in paragraph 0093 of Japanese Patent No. 5168903. The ion exchange capacity of fluorine-containing polymer A6 was 1.00 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 A6 was 85 mol%, and the ratio of units based on TFE to units based on monomer m2 was 85:15 in molar ratio. 【0145】[Fluorination Treatment] 20 g of powder of fluorine-containing polymer A6 obtained by the above procedure was uniformly dispersed on a PFA petri dish in a nickel reactor and placed in the 1.1 L reactor. Then, a mixture of 20% fluorine gas and 80% nitrogen gas was introduced into the reactor at a gauge pressure of 0.2 MPa, and the reactor was maintained at 190°C for 5 hours to perform the fluorination treatment. After the treatment, the fluorine gas was exhausted, the polymer was removed, and it was pulverized in a pulverizer to obtain fluorine-containing polymer F6. 【0146】 <Fluorine-containing polymer F7> Fluorine-containing polymer A7 was manufactured with reference to the description in paragraph 0200 of Japanese Patent Application Publication No. 2015-099772. The ion exchange capacity of fluorine-containing polymer A7 was 1.43 meq / g, and the TQ value was 230°C. Furthermore, the content of units based on TFE relative to the total units contained in fluorine-containing polymer A7 was 72 mol%, and the ratio of units based on TFE to units based on monomer m2 was 72:28 in molar ratio. 【0147】 [Fluorination Treatment] 20 g of powder of fluorine-containing polymer A7 obtained by the above procedure was uniformly dispersed on a PFA petri dish in a nickel reactor and placed in the 1.1 L reactor. Then, a mixture of 20% fluorine gas and 80% nitrogen gas was introduced into the reactor at a gauge pressure of 0.2 MPa, and the reactor was maintained at 190°C for 5 hours to perform the fluorination treatment. After the treatment, the fluorine gas was exhausted, the polymer was removed, and it was pulverized in a pulverizer to obtain fluorine-containing polymer F7. 【0148】 <Fluorine-containing polymer F8> Fluorine-containing polymer A8 was manufactured with reference to the description in paragraph 0114 of Japanese Patent Application Publication No. 2010-018674. The ion exchange capacity of fluorine-containing polymer A8 was 1.55 meq / g, and the TQ value was 210°C. 【0149】[Fluorination Treatment] 20 g of powder of fluorine-containing polymer A8 obtained by the above procedure was uniformly dispersed on a PFA petri dish in a nickel reactor and placed in the 1.1 L reactor. Then, a mixture of 20% fluorine gas and 80% nitrogen gas was introduced into the reactor at a gauge pressure of 0.15 MPa, and the reactor was maintained at 200°C for 4 hours to perform the fluorination treatment. After the treatment, the fluorine gas was exhausted, the polymer was removed, and it was pulverized in a pulverizer to obtain fluorine-containing polymer F8. 【0150】 <Method for Manufacturing Electrolyte Membrane> Using the fluorine-containing polymers obtained in the above procedure, an electrolyte membrane was 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 a fluorine-containing polymer membrane (film thickness approximately 100 μm). The obtained membrane was 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 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. The resulting film was then air-dried between filter paper to obtain an electrolyte film. Infrared spectroscopy, Fenton test, and conductivity measurements were performed using the obtained electrolyte film, and the results are shown in Table 1. Note that in the table, the I obtained by infrared spectroscopy is shown. １６９０ / I ２３５０ This will be recorded as the "IR intensity ratio". 【0151】<Manufacturing of Membrane Electrode Assembly> A polymer (ion exchange capacity: 1.10 mm equivalent / gram dry resin) obtained by copolymerizing TFE and monomer m2, hydrolysis, and acid treatment was dispersed in a water / ethanol = 40 / 60 (mass%) solvent at a solid content concentration of 26.0% to obtain a dispersion (hereinafter also referred to as "dispersion Y"). Ethanol (18.06 g) and Zeolora-H (manufactured by Nippon Zeon) (10.58 g) were added to dispersion Y (33.0 g), and the mixture was mixed at 2,200 rpm for 5 minutes using a rotation-orbit mixer (manufactured by Thinky, Awatori Rentaro). Ethanol (46.44 g) and water (75.75 g) were added to the mixed composition (54.06 g), and further a specific surface area of ​​100 m² containing 74.8 mass% iridium was added. ２ 40.0 g of iridium oxide catalyst (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) was added. The resulting mixture was treated with a planetary bead mill (rotation speed 300 rpm) for 90 minutes to obtain an anode catalyst ink with a solid content concentration of 22% by mass. The anode catalyst ink was then placed on an ETFE sheet 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 an anode catalyst layer decal. 【0152】 A supported catalyst (TEC10E50E, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) (11 g), in which 46% by mass of platinum was supported on carbon powder, was mixed with water (59.4 g) and ethanol (39.6 g) and mixed and pulverized using an ultrasonic homogenizer to obtain a catalyst dispersion. To the catalyst dispersion, a mixture (29.2 g) was added, which consisted of dispersion Y (20.1 g), ethanol (11 g), and Zeolora-H (manufactured by Nippon Zeon Co., Ltd.) (6.3 g) that had been pre-mixed and kneaded. Furthermore, water (3.66 g) and ethanol (7.63 g) were added to the obtained dispersion and mixed with paint conditioner for 60 minutes to obtain a cathode catalyst ink with a solid content concentration of 10.0% by mass. The cathode catalyst ink was applied to an ETFE sheet using a die coater, dried at 80°C, and then heat-treated at 150°C for 15 minutes to obtain a platinum content of 0.4 mg / cm². ２ A cathode catalyst layer decal was obtained. 【0153】One side of a 7.0 cm x 7.0 cm electrolyte membrane was placed opposite the side of a 4.0 cm x 4.0 cm anode catalyst layer decal containing the catalyst layer, and the other side of the electrolyte membrane was placed opposite the side of a 4.0 cm x 4.0 cm cathode catalyst layer decal containing the catalyst layer. The two were then joined by heating and pressing 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 decal was removed. The ETFE sheets of the anode catalyst layer decal and cathode catalyst layer decal were then peeled off, resulting in an electrode area of ​​16 cm². ２ A membrane electrode assembly was obtained. Using the obtained membrane electrode assembly, the hydrogen permeability coefficient and fluorine release rate were measured, and the results are shown in Table 1. 【0154】 [Results] The fluorine-containing polymer used for the electrolyte membrane, along with various measurements and evaluation results of the obtained electrolyte membrane, are shown in Table 1. 【0155】 【0156】 From the results shown in Table 1, the fluorine-containing polymer contains units having two or more ion exchange groups, and the ion exchange capacity of the above fluorine-containing polymer is 0.70 to 1.50 milliequivalents / gram dry resin, １６９０ / I ２３５０ The electrolyte membranes of Examples 1 to 3 and 9, where the ratio is 0.150 or less, are considered to have excellent durability during electrolysis (evaluation of fluorine release rate) and excellent proton conductivity (evaluation of conductivity). On the other hand, I １６９０ / I ２３５０ The electrolyte membrane in Example 4, where is greater than 0.150, is considered to have poor durability during electrolysis. Furthermore, the electrolyte membranes in Examples 5 and 10, where the ion exchange capacity of the fluorine-containing polymer is outside the range of 0.70 to 1.50 milliequivalents / gram dry resin, are considered to have poor durability in the Fenton test and during electrolysis. The electrolyte membranes in Examples 6 and 8, which do not contain units having two or more ion exchange groups, are considered to have poor durability during electrolysis. １６９０ / I ２３５０ The value is within the range of 0.150 or less, which is excellent in the Fenton test but is considered to be inferior in durability during electrolysis. The electrolyte membrane of Example 7, which does not contain units having two or more ion exchange groups, is １６９０ / I ２３５０The value is within the range of 0.150 or less, and is considered to have excellent Fenton test performance and durability during electrolysis, but poor proton conductivity. From the results of Examples 1 to 10, in order to achieve both durability during electrolysis and proton conductivity, a fluorine-containing polymer containing a unit having two or more ion exchange groups is included, and the ion exchange capacity of the above fluorine-containing polymer is 0.70 to 1.50 milliequivalents / gram dry resin, and I １６９０ / I ２３５０ It is considered necessary that the value be 0.150 or less. 【0157】 10 Solid polymer electrolyte membrane 20 Membrane electrode assembly 22 Anode 24 Cathode 26 Catalyst layer 28 Gas diffusion layer 【0158】 Furthermore, the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2024-215275, filed on December 10, 2024, are incorporated herein by reference as disclosure of the present invention.

Claims

1. A solid polymer electrolyte membrane for a water electrolysis apparatus, wherein the solid polymer electrolyte membrane contains a fluorine-containing polymer having two or more units having ion exchange groups, the ion exchange capacity of the fluorine-containing polymer is 0.70 to 1.50 milliequivalents / gram dry resin, and the infrared spectrum obtained by measuring the fluorine-containing polymer by infrared spectroscopy is 2350 ± 30 cm⁻¹. －１ Maximum absorbance I ２３５０ 1690 ± 10 cm －１ Maximum absorbance I １６９０ A solid polymer electrolyte membrane in which the ratio of is 0.150 or less.

2. The solid polymer electrolyte membrane according to claim 1, wherein the ion exchange capacity of the fluorine-containing polymer is 0.90 to 1.35 milliequivalents / gram dry resin.

3. The solid polymer electrolyte membrane according to claim 1, wherein the ion exchange capacity of the fluorine-containing polymer is 1.25 to 1.50 milliequivalents / gram dry resin.

4. 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 (1-3). R ｆ１ This is a perfluoroalkylene group which may contain oxygen atoms between carbon atoms. ｆ２ is a perfluoroalkylene group which may contain oxygen atoms between single bonds or carbon atoms. M is a hydrogen atom, an alkali metal, or a quaternary ammonium cation. r is 0 or 1.

5. The solid polymer electrolyte membrane according to claim 4, wherein the fluorine-containing polymer comprises units based on tetrafluoroethylene and units represented by formula (1-3), the content of the units based on tetrafluoroethylene is 86 to 95 mol% of the total units in the fluorine-containing polymer, and the content of the units represented by formula (1-3) is 5 to 14 mol% of the total units in the fluorine-containing polymer.

6. The solid polymer electrolyte membrane according to claim 1, wherein the film thickness is 50 to 150 μm.

7. The solid polymer electrolyte membrane according to claim 1, wherein the amount of fluoride ions eluted in the Fenton test is 0.02% by mass or less relative to the total mass of fluorine atoms in the electrolyte membrane.

8. In the infrared spectrum obtained by measuring the fluorine-containing polymer by infrared spectroscopy, the maximum absorbance I at 2350 ± 30 cm －１ with respect to the maximum absorbance I at 1690 ± 10 cm ２３５０ is 0.070 or less. The solid polymer electrolyte membrane according to claim 1. －１ at １６９０ ​ 9. A membrane electrode assembly comprising an anode having a catalyst layer, a cathode having a catalyst layer, and a solid polymer electrolyte membrane according to any one of claims 1 to 8, disposed between the anode and the cathode.

10. A water electrolysis apparatus comprising the membrane electrode assembly described in claim 9.

11. 2 A / cm² when water is electrolyzed. ２ The hydrogen permeability coefficient in is 2.8 × 10⁻⁶. －６ cc・cm / cm ２ The water electrolysis apparatus according to claim 10, wherein the temperature is less than or equal to sec·atm.

12. A method for producing hydrogen, comprising producing hydrogen by electrolyzing water using the water electrolysis apparatus described in claim 10.

13. A fluorine-containing olefin is copolymerized with a monomer having two or more groups that can be converted into ion exchange groups. The polymer is then fluorinated by contact with a gas containing 5% to 40% by volume of fluorine gas, and the resulting polymer is formed into a film to obtain a precursor film. Subsequently, the groups in the precursor film that can be converted into ion exchange groups are converted into ion exchange groups, resulting in a resin with an ion exchange capacity of 0.70 to 1.50 milliequivalents / gram dry resin, and an infrared spectrum obtained by infrared spectroscopy showing 2350 ± 30 cm⁻¹. －１ Maximum absorbance I ２３５０ 1690 ± 10 cm －１ Maximum absorbance I １６９０ A method for producing a solid polymer electrolyte membrane, comprising a fluorine-containing polymer having a ratio of 0.150 or less.

14. The manufacturing method according to claim 13, wherein the temperature of the fluorination treatment is 150 to 250°C.

15. The manufacturing method according to claim 13, wherein the duration of the fluorination treatment is 1 to 7 hours.

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