Membrane electrode assembly, solid polymer electrolyte membrane, water electrolysis device, and electrolytic hydrogenation device

Abstract

The present invention provides: a membrane electrode assembly capable of suppressing increase in the electrolysis voltage if used in a water electrolysis system or an electrolytic hydrogenation system even in cases where the current density has increased; a solid polymer electrolyte membrane; a water electrolysis system; and an electrolytic hydrogenation system.　A membrane electrode assembly according to the present invention comprises an anode that has a catalyst layer, a cathode that has a catalyst layer, and a solid polymer electrolyte membrane that is arranged between the anode and the cathode; the solid polymer electrolyte membrane contains a woven fabric and a fluorine-containing polymer that has an ion exchange group; the aperture ratio of the woven fabric is 50% or more; and the ratio TAAVE / TBAVE, which is calculated from the average maximum film thickness TAAVE and the average minimum film thickness TBAVE of the solid polymer electrolyte membrane, is 1.20 or more.

Description

[Technical Field]

[0001] The present invention relates to a membrane electrode assembly, a solid polymer electrolyte membrane, a water electrolysis device, and an electrolytic hydrogenation device. [Background technology]

[0002] A membrane electrode assembly including a solid polymer electrolyte membrane can be used in a variety of applications, and various studies have been conducted on it. For example, a membrane electrode assembly is used in a solid polymer water electrolysis device (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 162511 Summary of the Invention [Problem to be solved by the invention]

[0004] In addition to water electrolysis devices, membrane electrode assemblies are sometimes used in electrolytic hydrogenation devices for toluene, etc. In recent years, there has been a demand for further improvement in the performance of these devices, specifically, a demand for reduction in electrolysis voltage. The present inventors evaluated a water electrolysis device having the membrane electrode assembly described in Patent Document 1 and found that there was a case where an increase in current density resulted in a large increase in electrolysis voltage, and that there was room for improvement.

[0005] The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a membrane electrode assembly, a solid polymer electrolyte membrane, a water electrolysis apparatus, and an electrolytic hydrogenation apparatus that, when applied to a water electrolysis apparatus or an electrolytic hydrogenation apparatus, can reduce the increase in electrolysis voltage even when the current density increases. [Means for solving the problem]

[0006] As a result of intensive research into the above-mentioned problems, the present inventors have discovered that in a membrane electrode assembly including a solid polymer electrolyte membrane, the solid polymer electrolyte membrane includes a woven fabric having a predetermined opening ratio, and the average maximum thickness TA AVE and average minimum film thickness TB AVE The ratio TA calculated from AVE / TB AVE is a predetermined value or more, the desired effect can be obtained, and this has led to the present invention.

[0007] That is, the inventors have found that the above problems can be solved by the following configuration. [1] A membrane electrode assembly comprising an anode having a catalyst layer, a cathode having a catalyst layer, and a solid polymer electrolyte membrane disposed between the anode and the cathode, the solid polymer electrolyte membrane comprises a fluorine-containing polymer having an ion-exchange group and a woven fabric, The woven fabric is composed of a thread A extending in one direction and a thread B extending in a direction substantially perpendicular to the thread A, The opening rate of the woven fabric is 50% or more, measuring a maximum thickness TA and a minimum thickness TB of the solid polymer electrolyte membrane for each of ten different cross sections obtained by cutting the solid polymer electrolyte membrane in a direction parallel to the extension direction of the yarns A in the solid polymer electrolyte membrane and at midpoints between the yarns A; Furthermore, the solid polymer electrolyte membrane is cut in a direction parallel to the direction in which the yarns B in the solid polymer electrolyte membrane extend and at midpoints between the yarns B, and the maximum thickness TA and minimum thickness TB of the solid polymer electrolyte membrane are measured for each of the ten different cross sections; The average minimum thickness TB obtained by arithmetically averaging the 20 TBs AVE The average maximum film thickness TA obtained by arithmetically averaging the 20 TAs obtained for AVE Percentage of TA AVE / TB AVE is 1.20 or more. [2] The membrane / electrode assembly according to claim 1, wherein the fluorine-containing polymer has an ion exchange capacity of 0.90 to 2.00 meq / g dry resin. [3] The membrane / electrode assembly according to [1] or [2], wherein the denier of the yarn A and the denier of the yarn B are each independently 15 to 50. [4] The above percentage TA AVE / TB AVE The membrane / electrode assembly according to any one of [1] to [3], wherein the value is 1.95 or more. [5] The membrane electrode assembly according to any one of [1] to [4], wherein the thread A and the thread B are each independently made of at least one material selected from the group consisting of polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyether ether ketone, and polyphenylene sulfide. [6] The membrane / electrode assembly according to any one of [1] to [5], wherein the density of the yarn A and the density of the yarn B each independently range from 70 to 150 threads / inch. [7] The membrane / electrode assembly according to any one of [1] to [6], wherein the ion exchange group is a sulfonic acid functional group. [8] The membrane / electrode assembly according to any one of [1] to [7], wherein the fluorine-containing polymer contains a unit based on a fluorine-containing olefin and a unit having a sulfonic acid type functional group and a fluorine atom. [9] The membrane / electrode assembly according to [8], wherein the fluorine-containing olefin is a fluoroolefin having 2 to 3 carbon atoms and having one or more fluorine atoms in the molecule.

[10] The membrane / electrode assembly according to [8] or [9], wherein the unit having a sulfonic acid functional group and a fluorine atom is a unit represented by the following formula (1): Formula (1) -[CF2-CF(-L-(SO3M) n )]- (In the formula, 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 n is 1 or 2. When n is 2, multiple Ms may be the same or different.)

[11] A water electrolysis device comprising the membrane electrode assembly according to any one of [1] to

[10] .

[12] An electrolytic hydrogenation apparatus comprising the membrane electrode assembly according to any one of [1] to

[10] .

[13] A solid polymer electrolyte membrane comprising a fluorine-containing polymer having an ion-exchange group and a woven fabric, The woven fabric is composed of a thread A extending in one direction and a thread B extending in a direction substantially perpendicular to the thread A, The opening rate of the woven fabric is 50% or more, measuring a maximum thickness TA and a minimum thickness TB of the solid polymer electrolyte membrane for each of ten different cross sections obtained by cutting the solid polymer electrolyte membrane in a direction parallel to the extension direction of the yarns A in the solid polymer electrolyte membrane and at midpoints between the yarns A; Furthermore, the solid polymer electrolyte membrane is cut in a direction parallel to the direction in which the yarns B in the solid polymer electrolyte membrane extend and at midpoints between the yarns B, and the maximum thickness TA and minimum thickness TB of the solid polymer electrolyte membrane are measured for each of the ten different cross sections; The average minimum thickness TB obtained by arithmetically averaging the 20 TBs AVE The average maximum film thickness TA obtained by arithmetically averaging the 20 TAs obtained for AVE Percentage of TA AVE / TB AVE is 1.20 or more.

[14] The solid polymer electrolyte membrane according to

[13] , wherein the fluorine-containing polymer has an ion exchange capacity of 0.90 to 2.00 meq / g dry resin.

[15] The above percentage TA AVE / TB AVE The solid polymer electrolyte membrane according to

[13] or

[14] , wherein the value of σ is 1.95 or more.

[16] The solid polymer electrolyte membrane according to any one of

[13] to

[15] , which is used in a membrane electrode assembly. [Effects of the Invention]

[0008] The present invention provides a membrane electrode assembly, a solid polymer electrolyte membrane, a water electrolysis apparatus, and an electrolytic hydrogenation apparatus that, when applied to a water electrolysis apparatus or an electrolytic hydrogenation apparatus, can reduce the increase in electrolysis voltage even when the current density increases. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing an example of a membrane electrode assembly of the present invention. [Figure 2] 1 is a schematic cross-sectional view showing an example of a solid polymer electrolyte membrane included in a membrane electrode assembly of the present invention, cut in a direction parallel to the direction in which thread A extends. [Figure 3] 2 is a schematic cross-sectional view showing an example of a solid polymer electrolyte membrane included in a membrane electrode assembly of the present invention, cut in a direction parallel to the direction in which thread B extends. FIG. [Figure 4] 1 is a schematic plan view showing an example of a woven fabric included in a solid polymer electrolyte membrane of the present invention, viewed in the thickness direction of the solid polymer electrolyte membrane. FIG. [Figure 5] 1 is a schematic cross-sectional view showing another example of a solid polymer electrolyte membrane included in a membrane electrode assembly of the present invention, cut in a direction parallel to the direction in which thread A extends. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following definitions of terms apply throughout the specification and claims, unless otherwise stated. The term "ion exchange group" refers to a group that can exchange at least a portion of the ions contained in the group for other ions, and examples thereof include the sulfonic acid type functional groups and carboxylic acid type functional groups described below. "Sulfonic acid functional group" refers to a sulfonic acid group (-SO3H) or a sulfonate group (-SO3M 2 However, M 2 is an alkali metal or quaternary ammonium cation. "Carboxylic acid type functional group" refers to a carboxylic acid group (-COOH) or a carboxylic acid salt group (-COOM) 1 However, M1 is an alkali metal or quaternary ammonium cation. A "precursor membrane" is a membrane that includes a polymer having groups that can be converted to ion-exchange groups. The term "groups that can be converted into ion-exchange groups" refers to groups that can be converted into ion-exchange groups by treatment such as hydrolysis or acidification. The term "group that can be converted into a sulfonic acid functional group" means a group that can be converted into a sulfonic acid functional group by treatment such as hydrolysis or acidification.

[0011] The term "unit" in a polymer refers to an atomic group derived from one molecule of a monomer formed by polymerization of the monomer. The unit may be an atomic group formed directly by the polymerization reaction, or may be an atomic group in which a part of the atomic group is converted into a different structure by treating the polymer obtained by the polymerization reaction.

[0012] A numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0013] [Membrane electrode assembly] The membrane electrode assembly of the present invention includes an anode having a catalyst layer, a cathode having a catalyst layer, and a solid polymer electrolyte membrane disposed between the anode and the cathode. The solid polymer electrolyte membrane includes a fluorine-containing polymer having ion-exchange groups and a woven fabric. The woven fabric is composed of threads A extending in one direction and threads B extending in a direction substantially perpendicular to threads A, and the opening ratio of the woven fabric is 50% or more. The average maximum thickness TA of the solid polymer electrolyte membrane is 50% or more. AVE and average minimum film thickness TB AVE The ratio TA calculated from AVE / TB AVE is 1.20 or more. When the membrane electrode assembly of the present invention is applied to a water electrolysis apparatus or an electrolytic hydrogenation apparatus, it is possible to reduce the increase in electrolysis voltage even when the current density increases. Although the details of the reason for this are not clear, it is presumed to be due to the following reasons. Percentage TA AVE / TB AVE When the surface roughness is 1.20 or more, the surface of the solid polymer electrolyte membrane has an uneven structure with a predetermined height difference. It is presumed that the uneven structure on the surface of the solid polymer electrolyte membrane generates convection of the liquid supplied to the surface of the membrane electrode assembly, improving the diffusibility of the liquid, and as a result, the increase in electrolysis voltage is reduced even when the current density is increased. Furthermore, when a woven fabric is present in the solid polymer electrolyte membrane, the membrane resistance of the solid polymer electrolyte membrane increases, which can lead to a problem of high electrolysis voltage. It is presumed that the use of a woven fabric with a predetermined opening ratio could address this problem and reduce the electrolysis voltage.

[0014] 1 is a cross-sectional view showing an example of a membrane electrode assembly of the present invention. The membrane electrode assembly 20 includes an anode 22 having a catalyst layer 26 and a gas diffusion layer 28, a cathode 24 having the catalyst layer 26 and the gas diffusion layer 28, and a solid polymer electrolyte membrane 10 disposed between the anode 22 and the cathode 24 in contact with the catalyst layer 26.

[0015] <Solid polymer electrolyte membrane> Fig. 2 is a schematic cross-sectional view showing an example of a solid polymer electrolyte membrane included in a membrane electrode assembly of the present invention when cut in a direction parallel to the extension direction of thread A, specifically, a cross-section exposed when the solid polymer electrolyte membrane is cut along line A-A' in Fig. 4 described below. In the cross-section of solid polymer electrolyte membrane 10 in Fig. 2, electrolyte 12 containing fluoropolymer (I) and threads 14a, 14b, and 14c arranged in electrolyte 12 are exposed. Threads 14a, 14b, and 14c correspond to threads B constituting woven fabric 14. Fig. 3 is a schematic cross-sectional view showing an example of a solid polymer electrolyte membrane included in a membrane electrode assembly of the present invention when cut in a direction parallel to the extension direction of thread B, specifically, a cross-section exposed when the solid polymer electrolyte membrane is cut along line B-B' in Fig. 4 described below. In the cross-section of solid polymer electrolyte membrane 10 in Fig. 3, electrolyte 12 containing fluoropolymer (I) and threads 14A, 14B, and 14C arranged in electrolyte 12 are exposed. Threads 14A, 14B, and 14C correspond to threads A constituting woven fabric 14. 4 is a plan view schematic diagram of the woven fabric 14 in the solid polymer electrolyte membrane 10 as viewed in the membrane thickness direction. As shown in FIG. 4, the woven fabric 14 includes threads 14A, 14B, and 14C that are threads A, and threads 14a, 14b, and 14c that are threads B that are approximately perpendicular to threads A.

[0016] Percentage TA in solid polymer electrolyte membrane AVE / TB AVE is 1.20 or more, and in view of the superior effects of the present invention, is preferably 1.35 or more, more preferably 1.60 or more, even more preferably 1.95 or more, and particularly preferably 2.10 or more. Percentage TA in solid polymer electrolyte membrane AVE / TB AVE The upper limit of is preferably 3.00 or less, more preferably 2.50 or less, and particularly preferably 2.30 or less, from the viewpoint of uniformity of the catalyst layer applied to the uneven surface of the solid polymer electrolyte membrane.

[0017] Percentage TA AVE / TB AVE Although there is no particular limitation on the method for making the value of Yarn A and Yarn B 1.20 or more, for example, a method of sandwiching a precursor membrane of the solid polymer electrolyte membrane between low-melting-point films described below and hot-pressing the resulting membrane during production of the solid polymer electrolyte membrane is exemplified. This causes the low-melting-point films to deform to conform to the surface shape of the precursor membrane, resulting in a solid polymer electrolyte membrane having an uneven surface structure in which the portions where Yarn A and Yarn B constituting the woven fabric are present are convex portions and the portions where Yarn A and Yarn B are not present are concave portions.

[0018] The proportion TA in the solid polymer electrolyte membrane of the present invention AVE / TB AVE The calculation method will be explained below. First, the solid polymer electrolyte membrane is cut in a direction parallel to the direction in which the yarns A in the solid polymer electrolyte membrane extend and at the midpoint between the yarns A, and the maximum thickness TA and minimum thickness TB of the solid polymer electrolyte membrane are measured for each of 10 different cross sections. Specifically, in the example of FIG. 4, the solid polymer electrolyte membrane 10 is cut along line A-A' located at the midpoint between thread 14A, which is thread A, and thread 14B. This exposes a cross section of the solid polymer electrolyte membrane 10 as shown in FIG. 2. Similarly, the solid polymer electrolyte membrane 10 is cut at a position other than the midpoint between thread 14A and thread 14B (for example, the midpoint between thread 14B and thread 14C) to expose a cross section of the solid polymer electrolyte membrane 10. After obtaining cross sections at 10 different locations in this manner, the maximum film thickness TA and minimum film thickness TB are measured for each cross section. Furthermore, the solid polymer electrolyte membrane is cut in a direction parallel to the direction in which the yarns B in the solid polymer electrolyte membrane extend and at the midpoint between the yarns B, and the maximum thickness TA and minimum thickness TB of the solid polymer electrolyte membrane are measured for each of 10 different cross sections. Specifically, in the example of FIG. 4, the solid polymer electrolyte membrane 10 is cut along line B-B' located at the midpoint between thread 14a and thread 14b, which are thread B. This exposes a cross section of the solid polymer electrolyte membrane 10 as shown in FIG. 3. Similarly, the solid polymer electrolyte membrane 10 is cut at a position other than the midpoint between thread 14a and thread 14b (for example, the midpoint between thread 14b and thread 14c) to expose a cross section of the solid polymer electrolyte membrane 10. After obtaining cross sections at 10 different locations in this manner, the maximum film thickness TA and minimum film thickness TB are measured for each cross section. Next, the arithmetic mean of the 20 TAs obtained was calculated as the average maximum film thickness TA AVE The arithmetic mean of the 20 TBs obtained was calculated as the average minimum thickness TB AVE Calculate the average minimum film thickness TB AVE Average maximum film thickness TA AVE The percentage of TA AVE / TB AVE Let's say.

[0019] Here, in measuring the thickness of the solid polymer electrolyte membrane, a sample of the solid polymer electrolyte membrane dried at 90° C. for 2 hours is used. The maximum film thickness TA and the minimum film thickness TB are measured using a magnified image (for example, 100 times) of the cross section of the solid polymer electrolyte membrane taken with an optical microscope (product name "BX-51", manufactured by Olympus Corporation).

[0020] Average maximum thickness of the solid polymer electrolyte membrane, TA AVE In terms of being able to further reduce the electrolysis voltage, the thickness is preferably 60 to 200 μm, more preferably 60 to 140 μm, further preferably 60 to 120 μm, and particularly preferably 60 to 100 μm. Average minimum thickness of solid polymer electrolyte membrane TB AVE In terms of further improving the strength of the membrane electrode assembly, the thickness is preferably 30 to 130 μm, more preferably 30 to 100 μm, further preferably 30 to 80 μm, and particularly preferably 30 to 50 μm.

[0021] In the example of FIG. 2, in the cross section of the solid polymer electrolyte membrane 10, the thickness of the solid polymer electrolyte membrane 10 gradually decreases from the yarn 14a toward the yarn 14b, reaches the minimum thickness TB, and then gradually increases to the maximum thickness TA. The cross-sectional shape of the solid polymer electrolyte membrane of the present invention is not limited to the cross-sectional shape shown in FIG. 2, and may be, for example, a cross-sectional shape as shown in FIG. 5 is a cross-sectional view showing another example of the solid polymer electrolyte membrane 10 cut in a direction parallel to the extension direction of the yarn A. In the example of FIG. 5, the thickness of the solid polymer electrolyte membrane 10 gradually decreases from yarn 14a to yarn 14b, reaching position C1 where the thickness is minimum TB, and after maintaining the minimum thickness TB up to position C2, the thickness of the solid polymer electrolyte membrane 10 gradually increases to a position where the thickness is maximum TA. In this way, the cross-sectional shape of the solid polymer electrolyte membrane 10 may have a flat region where the thickness is uniform from position C1 to position C2.

[0022] (woven fabric) The opening ratio of the woven fabric is 50% or more, preferably 55% or more, more preferably 60% or more, and particularly preferably 70% or more, in that the electrolysis voltage can be further reduced. The upper limit of the opening ratio of the woven fabric is preferably 90% or less, particularly preferably 80% or less, in order to provide a membrane electrode assembly with superior strength. The opening ratio of a woven fabric is calculated by the following formula (ε) based on the average diameter R1 of the threads and the average interval P1 between adjacent threads (hereinafter also referred to as "pitch P1"). Here, the average thread diameter R1 refers to the arithmetic mean value of the diameters of 10 different threads randomly selected based on a magnified (e.g., 100x) image of the woven fabric surface obtained using a microscope, and the pitch P1 refers to the arithmetic mean value of the intervals between 10 different points randomly selected based on a magnified (e.g., 100x) image of the woven fabric surface obtained using a microscope. Opening rate of woven fabric (%) = [P1 / (P1+R1)] 2 ×100 (ε)

[0023] The denier number of thread A and the denier number of thread B constituting the woven fabric are each independently 2 or more, preferably 10 or more, particularly preferably 15 or more, in terms of better strength and dimensional stability of the membrane electrode assembly. The upper limit of the denier of the yarn A and the denier of the yarn B constituting the woven fabric is preferably 60 or less, more preferably 50 or less, and particularly preferably 20 or less, from the viewpoint of further reducing the electrolysis voltage. The denier number is the mass of 9000m of yarn expressed in grams (g / 9000m).

[0024] The densities of the yarns A and B are each independently preferably 50 fibers / inch or more, more preferably 70 fibers / inch or more, and particularly preferably 90 fibers / inch or more, in terms of excellent strength and dimensional stability of the membrane electrode assembly, and preferably 200 fibers / inch or less, more preferably 150 fibers / inch or less, and particularly preferably 100 fibers / inch or less, in terms of further reducing the electrolysis voltage.

[0025] Yarn A and yarn B may be composed of either a monofilament consisting of one filament or a multifilament consisting of two or more filaments, with monofilament being preferred.

[0026] In order to improve the durability of the threads, it is preferable that thread A and thread B are each independently made of at least one material selected from the group consisting of polytetrafluoroethylene (hereinafter also referred to as "PTFE"), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (hereinafter also referred to as "PFA"), polyether ether ketone (hereinafter also referred to as "PEEK"), and polyphenylene sulfide (hereinafter also referred to as "PPS"). Yarn A and yarn B are preferably made of slit yarns, as these yarns have better durability and strength.

[0027] In the woven fabric, thread A and thread B are approximately perpendicular to each other. "Almost perpendicular" means that the angle between thread A and thread B is 90±10 degrees. Thread A may be either a warp thread or a weft thread of a woven fabric, but when thread A is a weft thread, thread B is a warp thread, and when thread A is a warp thread, thread B is a weft thread.

[0028] When the material constituting the woven fabric is PTFE, the basis weight of the woven fabric is 20 to 40 g / m, in order to obtain an excellent balance between the strength and the handleability of the solid polymer electrolyte membrane. 2 is preferable, and 30 to 40 g / m 2 is particularly preferred. When the material constituting the woven fabric is PFA, the weight of the woven fabric is 10 to 30 g / m, which provides an excellent balance between the strength of the solid polymer electrolyte membrane and ease of handling. 2 is preferably 10 to 20 g / m 2 is particularly preferred. When the material constituting the woven fabric is PEEK, the basis weight of the woven fabric is 5 to 40 g / m, in order to obtain an excellent balance between the strength of the solid polymer electrolyte membrane and the ease of handling. 2 is preferable, and 5 to 30 g / m 2 is particularly preferred. When the material constituting the woven fabric is PPS, the weight of the woven fabric is 5 to 40 g / m, which provides an excellent balance between the strength of the solid polymer electrolyte membrane and ease of handling. 2 is preferable, and 5 to 30 g / m 2 is particularly preferred.

[0029] (electrolyte) The electrolyte contains a fluorine-containing polymer (I). The ion exchange capacity of the fluoropolymer (I) is preferably at least 0.90 milliequivalents / gram dry resin, more preferably more than 1.10 milliequivalents / gram dry resin, still more preferably at least 1.15 milliequivalents / gram dry resin, particularly preferably at least 1.20 milliequivalents / gram dry resin, and most preferably at least 1.25 milliequivalents / gram dry resin, in order to enable further reduction in the electrolysis voltage. The upper limit of the ion exchange capacity of the fluoropolymer (I) is preferably not more than 2.00 milliequivalents / gram dry resin, more preferably not more than 1.50 milliequivalents / gram dry resin, particularly preferably not more than 1.43 milliequivalents / gram dry resin, in terms of obtaining a better solid polymer electrolyte membrane.

[0030] The fluoropolymer (I) used in the solid polymer electrolyte membrane may be one type, or two or more types may be laminated or mixed and used. Although the solid polymer electrolyte membrane may contain a polymer other than the fluoropolymer (I), it is preferable that the polymer in the solid polymer electrolyte membrane consists essentially of the fluoropolymer (I). "Consisting essentially of the fluoropolymer (I)" means that the content of the fluoropolymer (I) is 95 mass% or more based on the total mass of the polymers in the solid polymer electrolyte membrane. The upper limit of the content of the fluoropolymer (I) is 100 mass% based on the total mass of the polymers in the solid polymer electrolyte membrane. Specific examples of polymers other than the 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 atoms and / or sulfur atoms in the ring. Specific examples of the polyazole compound include polyimidazole compounds, polybenzimidazole compounds, polybenzobisimidazole compounds, polybenzoxazole compounds, polyoxazole compounds, polythiazole compounds, and polybenzothiazole compounds. In view of the oxidation resistance of the solid polymer electrolyte membrane, other polymers include polyphenylene sulfide resin and polyphenylene ether resin.

[0031] The fluoropolymer (I) has an ion-exchange group. Specific examples of the ion-exchange group include a sulfonic acid type functional group and a carboxylic acid type functional group, and the sulfonic acid type functional group is preferred from the viewpoint of further reducing the electrolysis voltage. In the following, embodiments of the fluoropolymer having a sulfonic acid type functional group (hereinafter also referred to as "fluoropolymer (S)") will be mainly described in detail.

[0032] The fluorine-containing polymer (S) preferably contains units based on a fluorine-containing olefin and units having a sulfonic acid type functional group and a fluorine atom. Examples of fluorine-containing olefins include fluoroolefins having 2 to 3 carbon atoms and 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 the production cost of the monomer, reactivity with other monomers, and excellent properties of the resulting fluoropolymer (S). The fluorine-containing olefins may be used alone or in combination of two or more.

[0033] As the unit having a sulfonic acid type functional group and a fluorine atom, a unit represented by the following formula (1) is preferred. Formula (1) -[CF2-CF(-L-(SO3M) n )]-

[0034] In the formula, L is an (n+1)-valent perfluorohydrocarbon group which may contain an etheric oxygen atom. The etheric oxygen atom may be located at the terminal or between carbon atoms in the perfluorohydrocarbon group. The number of carbon atoms in the (n+1)-valent perfluorohydrocarbon group is preferably 1 or more, particularly preferably 2 or more, and is preferably 20 or less, particularly preferably 10 or less.

[0035] L is preferably an (n+1)-valent perfluoroaliphatic hydrocarbon group which may contain an etheric oxygen atom, and particularly preferably a divalent perfluoroalkylene group which may contain an etheric oxygen atom, in the embodiment where n=1, or a trivalent perfluoroaliphatic hydrocarbon group which may contain an etheric oxygen atom, in the embodiment where n=2. The divalent perfluoroalkylene group may be either linear or branched.

[0036] M is a hydrogen atom, an alkali metal, or a quaternary ammonium cation. n is 1 or 2. When n is 2, multiple Ms may be the same or different.

[0037] The unit represented by formula (1) is preferably a unit represented by formula (1-1), a unit represented by formula (1-2), a unit represented by formula (1-3) or a unit represented by formula (1-4). Formula (1-1) -[CF2-CF(-OR f1 -SO3M)]- Formula (1-2) -[CF2-CF(-R f1 -SO3M)]-

[0038] [ka]

[0039] [ka]

[0040] R f1 is a perfluoroalkylene group which may contain an oxygen atom between carbon atoms. The number of carbon atoms in the perfluoroalkylene group is preferably 1 or more, particularly preferably 2 or more, and is preferably 20 or less, particularly preferably 10 or less.

[0041] R f2 is a perfluoroalkylene group which may contain a single bond or an oxygen atom between carbon atoms. The number of carbon atoms in the perfluoroalkylene group is preferably 1 or more, particularly preferably 2 or more, and is preferably 20 or less, particularly preferably 10 or less.

[0042] R f3 is a perfluoroalkylene group which may contain a single bond or an oxygen atom between carbon atoms. The number of carbon atoms in the perfluoroalkylene group is preferably 1 or more, particularly preferably 2 or more, and is preferably 20 or less, particularly preferably 10 or less.

[0043] r is 0 or 1. m is 0 or 1. M is a hydrogen atom, an alkali metal, or a quaternary ammonium cation.

[0044] Of the units represented by formula (1-1) and (1-2), the units represented by formula (1-5) are more preferred. Formula (1-5) -[CF2-CF(-(CF2) x -(OCF2CFY) y -O-(CF2) z -SO3M)]- x is 0 or 1, y is an integer of 0 to 2, z is an integer of 1 to 4, and Y is F or CF3. M is as defined above.

[0045] Specific examples of the unit represented by formula (1-1) include the following units: In the formula, w is an integer of 1 to 8, and x is an integer of 1 to 5. The definition of M in the formula is as described above. -[CF2-CF(-O-(CF2)w -SO3M)]- -[CF2-CF(-O-CF2CF(CF3)-O-(CF2) w -SO3M)]- -[CF2-CF(-(O-CF2CF(CF3)) x -SO3M)]-

[0046] Specific examples of the unit represented by formula (1-2) include the following units: In the formula, w is an integer of 1 to 8. The definition of M in the formula is as described above. -[CF2-CF(-(CF2) w -SO3M)]- -[CF2-CF(-CF2-O-(CF2) w -SO3M)]-

[0047] The unit represented by formula (1-3) is preferably a unit represented by formula (1-3-1), where M is defined as above.

[0048] [ka]

[0049] R f4 is a linear perfluoroalkylene group having 1 to 6 carbon atoms, and R f5 is a single bond or a linear perfluoroalkylene group having 1 to 6 carbon atoms which may contain an oxygen atom between carbon atoms. The definitions of r and M are as described above.

[0050] Specific examples of the unit represented by formula (1-3-1) include the following.

[0051] [ka]

[0052] The unit represented by formula (1-4) is preferably a unit represented by formula (1-4-1). f1 , R f2and M is defined as above.

[0053] [ka]

[0054] Specific examples of the unit represented by formula (1-4-1) include the following.

[0055] [ka]

[0056] The unit having a sulfonic acid type functional group and a fluorine atom may be used alone or in combination of two or more.

[0057] In the case of a fluoropolymer having a carboxylic acid type functional group (hereinafter referred to as "fluoropolymer (C)"), it preferably contains a unit based on a fluorine-containing olefin and a unit having a carboxylic acid type functional group and a fluorine atom. Specific examples of the fluorine-containing polymer (C) include the following compounds. CF2=CFOCF2CF(CF3)OCF2CF2COOCH3, CF2=CFOCF2CF2COOCH3, CF2=CFOCF2CF2CF2COOCH3, CF2=CFOCF2CF2CF2OCF2CF2COOCH3, CF2=CFOCF2CF2CF2CF2CF2COOCH3, CF2=CFOCF2CF(CF3)OCF2CF2CF2COOCH3.

[0058] The fluorine-containing polymer (I) may contain units based on other monomers other than the units based on a fluorine-containing olefin and the units having a sulfonic acid type functional group and a fluorine atom. Other examples of monomers include CF2=CFR f6 (However, R f6is a perfluoroalkyl group having 2 to 10 carbon atoms, CF2=CF-OR f7 (However, R f7 is a perfluoroalkyl group having 1 to 10 carbon atoms), CF2=CFO(CF2) v CF=CF2 (where v is an integer of 1 to 3). The content of units based on other monomers is preferably at most 30 mass % based on all units in the fluoropolymer (I) from the viewpoint of maintaining ion exchange performance.

[0059] The solid polymer electrolyte membrane may have a single-layer structure or a multi-layer structure. In the case of a multi-layer structure, for example, a mode in which a plurality of layers containing the fluoropolymer (I) and having different ion exchange capacities are laminated is mentioned.

[0060] (Method of manufacturing a solid polymer electrolyte membrane) Examples of a method for producing a solid polymer electrolyte membrane include a method in which a polymer of a fluorine-containing monomer having a group convertible to an ion-exchange group (hereinafter also referred to as "fluoropolymer (I')") and a membrane (hereinafter also referred to as "precursor membrane") containing a woven fabric are produced, and then the group convertible to an ion-exchange group in the precursor membrane is converted into an ion-exchange group.

[0061] Here, a preferred embodiment of the method for producing the precursor membrane includes, for example, a method in which both surfaces of a laminate in which the fluoropolymer (I') is arranged on both surfaces of a woven fabric are sandwiched between transfer substrates such as low-melting point films having a melting point of 70 to 180°C, followed by hot pressing. Specific examples of low melting point films include polyethylene films, polypropylene films, and polystyrene films.

[0062] The form of the woven fabric is as described above. The fluoropolymer (I') is preferably a polymer (hereinafter also referred to as "fluoropolymer (S')") of a fluoromonomer having a group that can be converted into a sulfonic acid type functional group (hereinafter also referred to as "fluoromonomer (S')"), and particularly preferably a copolymer of a fluorine-containing olefin and a monomer having a group that can be converted into a sulfonic acid type functional group and a fluorine atom. The fluoropolymer (S') will be described in detail below.

[0063] As the method for copolymerizing the fluoropolymer (S'), known methods such as solution polymerization, suspension polymerization and emulsion polymerization can be used.

[0064] Examples of the fluorine-containing olefin include those exemplified above, and TFE is preferred from the viewpoints of the production cost of the monomer, reactivity with other monomers, and excellent properties of the resulting fluorine-containing polymer (S). The fluorine-containing olefins may be used alone or in combination of two or more.

[0065] The fluorine-containing monomer (S') may be a compound having one or more fluorine atoms in the molecule, an ethylenic double bond, and a group that can be converted into a sulfonic acid type functional group. As the fluorine-containing monomer (S'), a compound represented by formula (2) is preferred from the viewpoints of the production cost of the monomer, the reactivity with other monomers, and excellent properties of the resulting fluorine-containing polymer (S). Equation (2) CF2 = 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 into a sulfonic acid functional group. The group that can be converted into a sulfonic acid functional group is preferably a functional group that can be converted into a sulfonic acid functional group by hydrolysis. Specific examples of groups that can be converted into a sulfonic acid functional group include -SO2F, -SO2Cl, and -SO2Br.

[0066] The compound represented by formula (2) is preferably a compound represented by formula (2-1), a compound represented by formula (2-2), a compound represented by formula (2-3) or a compound represented by formula (2-4). Equation (2-1) CF2=CF-OR f1 -A Equation (2-2) CF2=CF-R f1 -A

[0067] [ka]

[0068] R in the formula f1 , R f2 , r and A are as defined above.

[0069] [ka]

[0070] R in the formula f1 , R f2 , R f3 , r, m and A are as defined above.

[0071] As the compound represented by formula (2-1) and the compound represented by formula (2-2), the compound represented by formula (2-5) is preferred. Equation (2-5) CF2 = CF-(CF2) x -(OCF2CFY) y -O-(CF2) z -SO3M In the formula, M, x, y, z and Y are defined as above.

[0072] Specific examples of the compound represented by formula (2-1) include the following compounds: In the formula, w is an integer of 1 to 8, and x is an integer of 1 to 5. CF2=CF-O-(CF2) w -SO2F CF2=CF-O-CF2CF(CF3)-O-(CF2) w -SO2F CF2=CF-[O-CF2CF(CF3)] x -SO2F

[0073] Specific examples of the compound represented by formula (2-2) include the following compounds: In the formula, w is an integer of 1 to 8. CF2=CF-(CF2) w -SO2F CF2=CF-CF2-O-(CF2) w -SO2F

[0074] The compound represented by formula (2-3) is preferably a compound represented by formula (2-3-1).

[0075] [ka]

[0076] R in the formula f4 , R f5 , r and A are as defined above.

[0077] Specific examples of the compound represented by formula (2-3-1) include the following.

[0078] [ka]

[0079] The compound represented by formula (2-4) is preferably a compound represented by formula (2-4-1).

[0080] [ka]

[0081] R in the formula f1 , R f2 and A are defined as above.

[0082] Specific examples of the compound represented by formula (2-4-1) include the following.

[0083] [ka]

[0084] The fluorine-containing monomer (S') may be used alone or in combination of two or more kinds. In the production of the fluoropolymer (S'), in addition to the fluorine-containing olefin and the fluorine-containing monomer (S'), other monomers may be used, such as those exemplified above.

[0085] The ion exchange capacity of the fluoropolymer (I') can be adjusted by changing the content of groups that can be converted into ion exchange groups in the fluoropolymer (I').

[0086] A specific example of a method for producing a precursor membrane is an extrusion method. More specifically, a method in which a membrane (I') made of a fluoropolymer (I') is formed, and then the membrane (I'), woven fabric, and membrane (I') are arranged in this order, and these are laminated using a laminating roll or a vacuum laminating device.

[0087] Specific examples of methods for converting groups in the precursor membrane that can be converted into ion-exchange groups into ion-exchange groups include methods in which the precursor membrane is subjected to a hydrolysis treatment or an acid-form treatment. Among these, the method of bringing the precursor film into contact with an alkaline aqueous solution is preferred.

[0088] Specific examples of the method for contacting the precursor film with the alkaline aqueous solution include a method of immersing the precursor film in the alkaline aqueous solution and a method of spraying the alkaline aqueous solution onto the surface of the precursor film. The temperature of the alkaline aqueous solution is preferably 30 to 100° C., particularly preferably 40 to 100° C. The contact time between the precursor film and the alkaline aqueous solution is preferably 3 to 150 minutes, particularly preferably 5 to 50 minutes.

[0089] The alkaline aqueous solution preferably contains an alkali metal hydroxide, a water-soluble organic solvent, and water. Alkali metal hydroxides include sodium hydroxide and potassium hydroxide. In this specification, a water-soluble organic solvent is an organic solvent that dissolves easily in water, and specifically, an organic solvent having a solubility of 0.1 g or more in 1000 ml of water (20°C) is preferred, and an organic solvent having a solubility of 0.5 g or more is particularly preferred. The water-soluble organic solvent preferably contains at least one selected from the group consisting of aprotic organic solvents, alcohols, and aminoalcohols, and particularly preferably contains an aprotic organic solvent. The water-soluble organic solvent may be used alone or in combination of two or more kinds.

[0090] 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.

[0091] The concentration of the alkali metal hydroxide in the alkaline aqueous solution is preferably from 1 to 60% by mass, particularly preferably from 3 to 55% by mass. The content of the water-soluble organic solvent in the alkaline aqueous solution is preferably from 1 to 60% by mass, particularly preferably from 3 to 55% by mass. The concentration of water in the alkaline aqueous solution is preferably 39 to 80% by mass.

[0092] After the precursor film is brought into contact with the alkaline aqueous solution, a treatment for removing the alkaline aqueous solution may be carried out. As a method for removing the alkaline aqueous solution, for example, a method for washing the precursor film that has been brought into contact with the alkaline aqueous solution with water may be mentioned.

[0093] After contacting the precursor membrane with the alkaline aqueous solution, the resulting membrane may be contacted with an acidic aqueous solution to convert the ion exchange groups into the acid form. Specific examples of the method for contacting the precursor film with the acidic aqueous solution include a method of immersing the precursor film in the acidic aqueous solution and a method of 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.

[0094] <Anode and cathode> The anode and cathode each have a catalyst layer. In the example of Figure 1, the anode 22 and cathode 24 each have a catalyst layer 26 and a gas diffusion layer 28.

[0095] A specific example of the catalyst layer is a layer containing a catalyst and a polymer having an ion-exchange group. Specific examples of the catalyst include a supported catalyst in which a carbon support carries a catalyst containing platinum, a platinum alloy, or a platinum catalyst having a core-shell structure, an iridium oxide catalyst, an alloy containing iridium oxide, and a catalyst containing iridium oxide having a core-shell structure. An example of the carbon support is carbon black powder. The polymer having an ion-exchange group may be a fluorine-containing polymer having an ion-exchange group.

[0096] The gas diffusion layer has the function of diffusing gas uniformly into the catalyst layer and also functions as a current collector. Specific examples of the gas diffusion layer include carbon paper, carbon cloth, and carbon felt. The gas diffusion layer is preferably treated with PTFE or the like to be water repellent. Although the membrane electrode assembly of FIG. 1 includes a gas diffusion layer 28, the gas diffusion layer is an optional component and does not necessarily have to be included in the membrane electrode assembly.

[0097] The 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, from the viewpoint of achieving better effects of the present invention. The film thickness of the anode and cathode is measured using an image obtained by measuring a cross section of the membrane electrode assembly cut in the thickness direction with an optical microscope, and is the arithmetic average value at any 20 points.

[0098] <Method for manufacturing membrane electrode assembly> Examples of methods for producing a membrane electrode assembly include a method in which a catalyst layer is formed on a solid polymer electrolyte membrane and the resulting assembly is further sandwiched between gas diffusion layers, and a method in which a catalyst layer is formed on a gas diffusion layer to form electrodes (anode, cathode), and the solid polymer electrolyte membrane is sandwiched between these electrodes. The catalyst layer can be produced by applying a coating liquid for forming a catalyst layer to a predetermined position and drying it as necessary. The coating liquid for forming a catalyst layer is a liquid in which a polymer having an ion exchange group and a catalyst are dispersed in a dispersion medium.

[0099] <Application> The membrane electrode assembly of the present invention can be used in a water electrolysis device (specifically, a solid polymer water electrolysis device), and can also be used as a diaphragm in an electrolytic hydrogenation device for aromatic compounds (e.g., toluene).

[0100] [Water electrolysis device] The water electrolysis device of the present invention includes the above-described membrane electrode assembly. Because the water electrolysis device of the present invention includes the above-described membrane electrode assembly, the increase in electrolysis voltage is small even when the current density increases. The water electrolysis device of the present invention may have the same configuration as known water electrolysis devices, except that it includes the above-described membrane electrode assembly.

[0101] [Electrolytic hydrogenation equipment] The electrolytic hydrogenation apparatus of the present invention includes the above-described membrane electrode assembly. The electrolytic hydrogenation apparatus of the present invention can have the same configuration as known electrolytic hydrogenation apparatuses, except that it includes the above-described membrane electrode assembly.

[0102] [Solid polymer electrolyte membrane] The solid polymer electrolyte membrane of the present invention is a solid polymer electrolyte membrane comprising a fluorine-containing polymer having an ion-exchange group and a woven fabric. The woven fabric is composed of threads A extending in one direction and threads B extending in a direction substantially perpendicular to threads A, and the opening ratio of the woven fabric is 50% or more. AVE and average minimum film thickness TB AVE The ratio TA calculated from AVE / TB AVE is 1.20 or more. The solid polymer electrolyte membrane of the present invention is suitably used as the solid polymer electrolyte membrane contained in the above-mentioned membrane electrode assembly, and when applied to a water electrolysis apparatus or an electrolytic hydrogenation apparatus, can reduce the increase in electrolysis voltage even when the current density increases. The preferred embodiments of the solid polymer electrolyte membrane of the present invention are the same as those of the solid polymer electrolyte membrane contained in the membrane electrode assembly of the present invention described above, and therefore, the description thereof will be omitted. [Example]

[0103] The present invention will be described in detail below with reference to examples. Examples 1 to 4 are working examples, and Examples 5 to 7 are comparative examples. However, the present invention is not limited to these examples. [Film thickness] Average maximum thickness of the solid polymer electrolyte membrane, TA AVE , average minimum film thickness TB AVE , and the ratio TA AVE / TB AVE was calculated according to the method described in the section describing the solid polymer electrolyte membrane.

[0104] [Ion exchange capacity of fluoropolymer] The fluoropolymer was placed in a glove box filled with dry nitrogen for 24 hours, and the dry mass of the fluoropolymer was measured. Thereafter, the fluoropolymer was immersed in a 2 mol / L aqueous sodium chloride solution at 60°C for 1 hour. The fluoropolymer was washed with ultrapure water, then removed, and the solution in which the fluoropolymer had been immersed was titrated with a 0.1 mol / L aqueous sodium hydroxide solution to determine the ion exchange capacity (milli-equivalents / g dry resin) of the fluoropolymer.

[0105] [Weight of woven fabric] The raw woven fabric used was cut into a size of 20 x 20 cm, and the mass was measured. The above measurement was carried out five times, and the weight of the woven fabric (g / m 2 ) was sought. [Density of warp and weft threads that make up the woven fabric] The density of the warp and weft threads that make up the woven fabric was calculated using the following method: For each warp and weft thread, the length of 10 threads was measured five times from an optical microscope image, and the average value was converted into density (threads / inch).

[0106] [Opening rate of woven fabric] The raw woven fabric used was cut into a sample of 20 x 20 cm, and the calculation was carried out according to the method described in the description of the woven fabric above. [Warp denier and weft denier of woven fabric] The denier of the warp yarns and the denier of the weft yarns constituting the woven fabric were calculated according to the following method: Five open areas were randomly selected, the open area ratio was calculated from the image observed under an optical microscope, and the average value was taken as the open area ratio.

[0107] [Electrolytic voltage evaluation test] TFE and the monomer (X) described below were copolymerized, and the resulting polymer (ion exchange capacity: 1.10 meq / g dry resin) was converted to an acid form through hydrolysis and acid treatment. This polymer was dispersed in a 40 / 60 wt% water / ethanol solvent to a solids concentration of 25.8% (hereinafter referred to as "Dispersion X"). Ethanol (0.52 g) and water (3.34 g) were added to the resulting Dispersion X (19.0 g), followed by the addition of 13.0 g of an iridium oxide catalyst (Tanaka Kikinzoku) containing 76 wt% iridium. The resulting mixture was milled in a planetary bead mill (300 rpm) for 30 minutes, after which water (4.49 g) and ethanol (4.53 g) were added. This mixture was then milled in a planetary bead mill (200 rpm) for 60 minutes to obtain an anode catalyst ink with a solids concentration of 40 wt%. An anode catalyst ink was applied to one surface of the solid polymer electrolyte membrane obtained by the procedure described below at a concentration of 2.0 mg / cm of iridium. 2 The coated film was then dried at 80°C for 10 minutes, and further subjected to a heat treatment at 150°C for 15 minutes to obtain an electrolyte membrane with an anode catalyst layer.

[0108] Water (59.4 g) and ethanol (39.6 g) were added to 11 g of a supported catalyst ("TEC10E50E" manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) in which 46 mass% platinum was supported on carbon powder, and the mixture was mixed and pulverized using an ultrasonic homogenizer to obtain a catalyst dispersion. To the catalyst dispersion was added a mixture (29.2 g) of Dispersion X (20.1 g), ethanol (11 g), and Zeorola-H (manufactured by Zeon Corporation) (6.3 g) that had been mixed and kneaded in advance. Water (3.66 g) and ethanol (7.63 g) were then added to the resulting dispersion, and the mixture was mixed for 60 minutes using a paint conditioner to adjust the solids concentration to 10.0% by mass, yielding a cathode catalyst ink. 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 reduce the platinum content to 0.4 mg / cm. 2 As a result, a cathode catalyst layer decal of 1000 nm was obtained.

[0109] The surface of the electrolyte membrane with an anode catalyst layer that does not have an anode catalyst layer was placed opposite the surface of the cathode catalyst layer decal that has a catalyst layer, and the membrane was hot-pressed at a temperature of 150°C for 2 minutes under a pressure of 3 MPa to bond the electrolyte membrane with an anode catalyst layer to the cathode catalyst layer. After the temperature was lowered to 70°C, the pressure was released and the membrane was removed. The ETFE sheet of the cathode catalyst layer decal was peeled off, and the electrode area was reduced to 25 cm. 2 As a result, a membrane electrode assembly of 1000 .mu.m was obtained.

[0110] The membrane electrode assembly obtained by the above procedure was heat treated at 150° C. for 15 minutes, and then set in a water electrolysis evaluation jig EH50-25 (manufactured by Greenlight Innovation). Next, to fully hydrate the solid polymer electrolyte membrane and the ionomers at 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 12 hours. After that, the cathode side was purged with nitrogen. After purging with nitrogen, pure water with a conductivity of 1.0 μS / cm or less, a temperature of 80°C, and normal pressure was supplied to the anode side at a flow rate of 50 mL / min. The generated gas pressure on the cathode side was kept at atmospheric pressure. A current of 0 to 50 A (current density 0 to 2 A / cm) was supplied from a Kikusui Electronics PWR1600L DC power supply. 2 The current was increased stepwise by 2.5 A in the range of 10 min at each step, and the current density was 2 A / cm. 2 The electrolysis voltage Vx (unit: V) and the current density 4A / cm 2 The electrolysis voltage Vy (unit: V) at this time and the value of the electrolysis voltage Vy (unit: V) were measured and evaluated according to the following criteria. ◎: Vy-Vx≦30 ○: 30 <Vy-Vx≦50 ×: 50 <Vy-Vx

[0111] [Production of Fluorine-Containing Polymer (S'-1)] CF2=CF2 and a monomer (X) represented by the following formula (X) were copolymerized to obtain a fluorine-containing polymer (S'-1) (ion exchange capacity: 1.25 meq / g dry resin). CF2=CF-O-CF2CF(CF3)-O-CF2CF2-SO2F ···(X)

[0112] The ion exchange capacity described in the above [Production of fluoropolymer (S'-1)] represents the ion exchange capacity of the fluoropolymer obtained when the fluoropolymer (S'-1) is hydrolyzed by the procedure described below.

[0113] [Production of film-coated substrate Y1] A fluoropolymer (S'-1) was attached to a substrate made of a linear low-density polyethylene (LLDPE) film (melting point: 110-120°C) by melt extrusion to obtain a film-attached substrate Y1 in which a film α1 (film thickness: 45 μm) made of the fluoropolymer (S'-1) was formed on the substrate.

[0114] [Production of film-coated substrate Y2] A fluoropolymer (S'-1) was attached to a substrate made of a linear low-density polyethylene (LLDPE) film (melting point: 110-120°C) by melt extrusion to obtain a film-attached substrate Y2 in which a film α2 (film thickness: 30 μm) made of the fluoropolymer (S'-1) was formed on the substrate.

[0115] [Production of film-coated substrate Y3] A fluoropolymer (S'-1) was attached to a substrate made of a linear low-density polyethylene (LLDPE) film (melting point: 110-120°C) by melt extrusion to obtain a film-attached substrate Y3 in which a film α3 (film thickness: 15 μm) made of the fluoropolymer (S'-1) was formed on the substrate.

[0116] [Production of film-coated substrate Y4] A fluoropolymer (S'-1) was attached to a substrate made of a polyethylene terephthalate (PET) film (melting point: 250-260°C) by melt extrusion to obtain a film-attached substrate Y4 in which a film α1 (film thickness: 45 μm) made of the fluoropolymer (S'-1) was formed on the substrate.

[0117] [Production of film-coated substrate Y5] A fluoropolymer (S'-1) was attached to a substrate made of a polyethylene terephthalate (PET) film (melting point: 250-260°C) by melt extrusion to obtain a film-attached substrate Y5 in which a film α2 (film thickness: 30 μm) made of the fluoropolymer (S'-1) was formed on the substrate.

[0118] [Woven fabric manufacturing] Woven fabric A1 was obtained by plain weaving 49.8 denier PTFE yarns as warp and weft yarns so that the density of the PTFE yarns was 90 threads / inch. The weight of the woven fabric A1 was 39.2 g / m 2 The warp and weft were made of slit yarns. In addition, woven fabrics A2 to A3 were manufactured in the same manner as woven fabric A1, except that the type and denier of the material constituting the warp and weft threads, as well as the density and basis weight of the woven fabric, were changed to the values ​​listed in Table 1.

[0119] [Example 1] The substrate Y1 with film / woven fabric A1 / substrate Y1 with film were stacked in this order, with the substrate Y1 with film being positioned so that the film α1 in the substrate Y1 with film was in contact with the woven fabric A1. The overlapping components are placed at a temperature of 160°C and a surface pressure of 30 MPa / m. 2 After the substrates were heated and pressed for 10 minutes using a flat plate press, the substrates on both sides were peeled off at a temperature of 50°C to obtain a precursor film.

[0120] The precursor membrane was immersed in a solution of dimethyl sulfoxide / potassium hydroxide / water = 30 / 5.5 / 64.5 (mass ratio) at 95°C for 30 minutes to hydrolyze the groups in the precursor membrane that could be converted to sulfonic acid functional groups, converting them to K-type sulfonic acid functional groups, and then washed with water. The resulting membrane was then immersed in 1M sulfuric acid to convert the terminal groups from K-type to H-type, and then dried to obtain a solid polymer electrolyte membrane. The obtained solid polymer electrolyte membrane was used to measure the membrane thickness and to carry out an electrolysis voltage evaluation test. The results are shown in Table 1.

[0121] [Examples 2-4] A solid polymer electrolyte membrane was prepared in the same manner as in Example 1, except that the types of the film-attached substrate and the woven fabric were changed as shown in Table 1. The thickness of the solid polymer electrolyte membrane was measured, and an electrolysis voltage evaluation test was carried out.

[0122] [Example 5] The substrate Y4 with film / woven fabric A1 / substrate Y4 with film were stacked in this order, with the substrate Y4 with film being positioned so that the film α1 in the substrate Y4 with film was in contact with the woven fabric A1. The overlapping components are placed at a temperature of 200°C and a surface pressure of 30 MPa / m. 2 After the substrates were heated and pressed for 10 minutes using a flat plate press, the substrates on both sides were peeled off at a temperature of 50°C to obtain a precursor film. A solid polymer electrolyte membrane was produced in the same manner as in Example 1, except that the precursor membrane thus obtained was used, and the thickness of the solid polymer electrolyte membrane was measured and an electrolysis voltage evaluation test was carried out.

[0123] [Examples 6-7] A solid polymer electrolyte membrane was prepared in the same manner as in Example 5, except that the types of the film-attached substrate and the woven fabric were changed as shown in Table 1, and the thickness of the solid polymer electrolyte membrane was measured and an electrolysis voltage evaluation test was carried out.

[0124] "Denier (g / 9000m)" in Table 1 indicates the denier of the warp and weft yarns that make up the woven fabric. In all of Examples 1 to 7, the denier of the warp and weft yarns that make up the woven fabric was the same.

[0125] [Table 1]

[0126] As shown in Table 1, in a membrane electrode assembly including a solid polymer electrolyte membrane, the solid polymer electrolyte membrane includes a woven fabric with an opening ratio of 50% or more, and the proportion TA AVE / TB AVEIt was confirmed that if ρ is 1.20 or more, the increase in electrolysis voltage can be reduced even when the current density increases (Examples 1 to 4). [Explanation of symbols]

[0127] 10 Solid polymer electrolyte membrane 12 Electrolytes 14 Woven fabric 14a, 14b, 14c Thread A 14A, 14B, 14C Thread B 20 Membrane electrode assembly 22 Anode 24 cathode 26 Catalyst layer 28 Gas diffusion layer TA Maximum film thickness TB minimum film thickness C1,C2 position

[0128] The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2020-148732, filed on September 4, 2020, are hereby incorporated by reference as the disclosure of the specification of the present invention.

Claims

1. A membrane electrode assembly comprising: an anode having a catalyst layer; a cathode having a catalyst layer; and a solid polymer electrolyte membrane disposed between the anode and the cathode, the solid polymer electrolyte membrane comprises a fluorine-containing polymer having an ion-exchange group and a woven fabric, The woven fabric is composed of a thread A extending in one direction and a thread B extending in a direction substantially perpendicular to the thread A, The opening rate of the woven fabric is 50% or more, measuring a maximum thickness TA and a minimum thickness TB of the solid polymer electrolyte membrane for each of ten different cross sections obtained by cutting the solid polymer electrolyte membrane in a direction parallel to the extension direction of the yarns A in the solid polymer electrolyte membrane and at midpoints between the yarns A; Furthermore, the solid polymer electrolyte membrane is cut in a direction parallel to the extension direction of the yarns B in the solid polymer electrolyte membrane and at midpoints between the yarns B, and the maximum thickness TA and the minimum thickness TB of the solid polymer electrolyte membrane are measured for each of the ten different cross sections; The average minimum film thickness TB obtained by arithmetically averaging the 20 TBs obtained ＡＶＥ The average maximum film thickness TA obtained by arithmetically averaging the 20 TAs obtained ＡＶＥ The ratio of TA ＡＶＥ / TB ＡＶＥ is 1.20 or more.

2. 2. The membrane electrode assembly according to claim 1, wherein the ion exchange capacity of the fluoropolymer is 0.90 to 2.00 meq / g dry resin.

3. 3. The membrane electrode assembly according to claim 1, wherein the denier number of said thread A and the denier number of said thread B are each independently 15 to 50.

4. The ratio TA ＡＶＥ / TB ＡＶＥ The membrane electrode assembly according to any one of claims 1 to 3, wherein the σ is 1.95 or more.

5. 5. The membrane electrode assembly according to claim 1, wherein the threads A and the threads B are each independently made of at least one material selected from the group consisting of polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyether ether ketone, and polyphenylene sulfide.

6. 6. The membrane electrode assembly according to claim 1, wherein the density of said threads A and said threads B is independently 70 to 150 threads per inch.

7. 7. The membrane / electrode assembly according to claim 1, wherein the ion exchange group is a sulfonic acid type functional group.

8. 8. The membrane / electrode assembly according to claim 1, wherein the fluorine-containing polymer comprises a unit based on a fluorine-containing olefin and a unit having a sulfonic acid type functional group and a fluorine atom.

9. 9. The membrane electrode assembly according to claim 8, wherein the fluorine-containing olefin is a fluoroolefin having 2 to 3 carbon atoms and having one or more fluorine atoms in the molecule.

10. 10. The membrane / electrode assembly according to claim 8, wherein the unit having a sulfonic acid functional group and a fluorine atom is a unit represented by the following formula (1): Formula (1) -[CF ２ -CF(-L-(SO ３ M) ｎ )- (In the formula, 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 n is 1 or 2. When n is 2, multiple Ms may be the same or different.)

11. A water electrolysis device comprising the membrane electrode assembly according to any one of claims 1 to 10.

12. An electrolytic hydrogenation apparatus comprising the membrane electrode assembly according to any one of claims 1 to 10.

13. A solid polymer electrolyte membrane comprising a fluorine-containing polymer having an ion-exchange group and a woven fabric, The woven fabric is composed of a thread A extending in one direction and a thread B extending in a direction substantially perpendicular to the thread A, The opening rate of the woven fabric is 50% or more, measuring a maximum thickness TA and a minimum thickness TB of the solid polymer electrolyte membrane for each of ten different cross sections obtained by cutting the solid polymer electrolyte membrane in a direction parallel to the extension direction of the yarns A in the solid polymer electrolyte membrane and at midpoints between the yarns A; Furthermore, the solid polymer electrolyte membrane is cut in a direction parallel to the extension direction of the yarns B in the solid polymer electrolyte membrane and at midpoints between the yarns B, and the maximum thickness TA and the minimum thickness TB of the solid polymer electrolyte membrane are measured for each of the ten different cross sections; The average minimum film thickness TB obtained by arithmetically averaging the 20 TBs obtained ＡＶＥ The average maximum film thickness TA obtained by arithmetically averaging the 20 TAs obtained ＡＶＥ The ratio of TA ＡＶＥ / TB ＡＶＥ is 1.20 or more.

14. 14. The solid polymer electrolyte membrane according to claim 13, wherein the ion exchange capacity of the fluoropolymer is 0.90 to 2.00 meq / g dry resin.

15. The ratio TA ＡＶＥ / TB ＡＶＥ The solid polymer electrolyte membrane according to claim 13 or 14, wherein the σ is 1.95 or more.

16. The solid polymer electrolyte membrane according to any one of claims 13 to 15, which is used in a membrane electrode assembly.

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