Matrix material, nanofibers, electrolyte membrane, water electrolyzer, and fuel cell

Abstract

Provided are: a matrix material to be used in a composite film containing nanofibers and a matrix material, the matrix material comprising a polymer compound containing a sulfonic acid group and / or a phosphonic acid group; a nanofiber to be used in an electrolyte film comprising nanofibers and the matrix material, the nanofibers being formed by using a nanofiber polymer compound containing a sulfonic acid group and / or a phosphonic acid group; an electrolyte film comprising the nanofibers and the matrix material; a fuel cell provided with the electrolyte film; and a water electrolyzer which uses the electrolyte film.

Description

Matrix materials, nanofibers, electrolyte membranes, water electrolyzers and fuel cells

[0001] The present invention relates to a matrix material, a nanofiber, an electrolyte membrane, and a fuel cell, and more specifically to a matrix material, a nanofiber, and an electrolyte membrane and a fuel cell using the same, which have high proton conductivity under various humidity conditions at high temperatures, and which have sufficient ion conductivity (proton conductivity), gas barrier properties, and strength even when made into a thin film, and which can be produced without any complicated manufacturing process.

[0002] Composite membranes, which incorporate various materials into nonwoven fabrics, have been applied in various fields and have recently attracted attention as electrolyte membranes for polymer electrolyte fuel cells. Polymer electrolyte membranes have been proposed as electrolyte membranes for polymer electrolyte fuel cells, including fluorine-based electrolyte membranes such as Nafion®. However, these fluorine-based electrolyte membranes have problems such as poor power generation performance due to reduced proton conductivity under low-humidity conditions, membrane and catalyst degradation caused by side reactions associated with fuel gas permeation, poor membrane strength and poor long-term stability due to dimensional changes, and high costs due to the use of fluorine. Therefore, the development of hydrocarbon-based polymer electrolyte membranes that do not use fluorine materials is also being considered. For example, Patent Document 1 proposes a new nanofiber for a composite electrolyte membrane, which has high proton conductivity under high-temperature, unhumidified conditions and maintains sufficient ionic conductivity (proton conductivity), gas barrier properties, and strength even when thinned to a thickness of approximately 30 μm. Specifically, an electrolyte membrane has been proposed that includes specific nanofibers and a matrix resin, where the blending ratio of the nanofibers to the matrix resin is 100 to 1,000 parts by weight per 100 parts by weight of the nanofibers. It has been proposed that the matrix material can be sulfonated polyimide (SPI), sulfonated polybenzimidazole (SPBI), sulfonated polyphenylene (SPP), sulfonated polyphenylene oxide (SPPO), polyphenylene sulfide (SPPS), sulfonated polystyrene and its copolymer (SPSt), polyvinyl sulfonic acid and its copolymer (PVS), etc. Furthermore, Patent Document 2 proposes a composition that can form a cured product with excellent proton conductivity. Specifically, the composition proposed is a composition comprising a polymer compound having a group with a sulfonic acid group and carbon nanodots having a nitrogen-containing substituent, the polymer compound having a unit in which a sulfonic acid group is introduced into an arylene group or a heteroarylene group. Furthermore, Patent Document 3 proposes a polybenzimidazole / sulfonated polyaryleneisatin composite proton exchange membrane.Specifically, a polybenzimidazole / sulfonated polyaryleneisatin composite proton exchange membrane has been proposed. Non-Patent Documents 1 to 3 also propose matrix materials using polymers containing sulfonic acid groups.

[0003] Japanese Patent Publication No. 2020-181701 Japanese Patent Publication No. 2020-132735 Chinese Patent Publication No. 115627072

[0004] S. Lee et al. , Int. J. Hydrog. Energy, 2015, 40, 5390-5395. J. Miyake et al. , Sci. Adv. , 2017, 3, eaao0476. L. Guo et al. , Appl. Energ. Mater. , 2022, 5, 5525-5530.

[0005] However, the composite membranes disclosed in Patent Documents 1 to 3 and the matrix materials used therein do not meet the currently required performance requirements in terms of proton conductivity under various humidity conditions. Furthermore, they do not yet satisfy all of the required levels of proton conductivity, gas barrier properties, strength, and radical trapping ability. Furthermore, the proposal in Non-Patent Document 1 suffers from the problem of low proton conductivity, the proposal in Non-Patent Document 2 suffers from the problem of complex synthesis of the matrix material, resulting in proton conductivity that is not at the required level, and the proposal in Non-Patent Document 3 suffers from the problem of complex synthesis, although it does have a relatively high proton conductivity. In short, the composite membranes that can be used for electrolytes that have been proposed so far do not meet the required performance requirements, such as high proton conductivity under various humidity conditions at high temperatures, gas barrier properties, strength, and radical trapping ability, and the ease of manufacturing the constituent materials. Therefore, there is a current demand for the development of composite membranes that satisfy these performance requirements, as well as nanofiber bars and matrix materials that can be used for such composite membranes. Therefore, an object of the present invention is to provide a novel matrix material and nanofibers that constitute a composite membrane, and to provide a matrix material, nanofibers, electrolyte membrane, and fuel cell that have high proton conductivity under various humidity conditions at high temperatures, have sufficient ion conductivity (proton conductivity), gas barrier properties, and strength even when made thin, and are not complicated to manufacture.

[0006] The present inventors conducted extensive research to solve the above-mentioned problems, and discovered that the above-mentioned problems could be solved by using a polymer having acidic groups such as sulfonic acid groups at specific locations as the matrix material in a composite membrane comprising nanofibers and a matrix material. Further extensive research led to the completion of the present invention. Specifically, the present invention provides the following: 1. A matrix material for use in a composite membrane containing nanofibers and a matrix material, characterized in that it contains a polymer compound having sulfonic acid groups and / or phosphonic acid groups. 2. The matrix material according to 1, characterized in that the polymer compound is a fluorine-free compound. 3. The matrix material according to 1, wherein the polymer compound has a low-reducing group in the main chain skeleton. 4. The matrix material according to 3, wherein the low-reducing group is a ketone group or a substituent having a C═O structure. 5. The matrix material according to 1, wherein the polymer compound further contains a nitrogen-containing compound group. 6. The matrix material according to 1, wherein the polymer compound has a low-reducing group and a sulfonic acid group and / or a phosphonic acid group in the main chain skeleton. 7. 7. A nanofiber used in an electrolyte membrane containing nanofibers and the matrix material according to 1, characterized in that the nanofiber is formed using a polymer compound for nanofibers containing a sulfonic acid group and / or a phosphonic acid group. 8. An electrolyte membrane containing a matrix material containing a polymer compound containing a sulfonic acid group and / or a phosphonic acid group. 9. An electrolyte membrane comprising the nanofibers according to 7 and the matrix material according to 1. 10. A fuel cell comprising the electrolyte membrane according to 8 or 9. 11. A water electrolyzer using the electrolyte membrane according to 9.

[0007] The matrix material of the present invention is used together with nanofibers to form a composite membrane, which has high proton conductivity under various humidity conditions at high temperatures, and has sufficient ionic conductivity (proton conductivity), gas barrier properties, and strength even when thinned, and furthermore, the production of the matrix material is not complicated. The nanofibers of the present invention are used together with the matrix material of the present invention to form a composite membrane, which has high proton conductivity under various humidity conditions at high temperatures, and has sufficient ionic conductivity (proton conductivity), gas barrier properties, and strength even when thinned, and furthermore, the production of the matrix material is not complicated. The composite membrane of the present invention has high proton conductivity under various humidity conditions at high temperatures, and has sufficient ionic conductivity (proton conductivity), gas barrier properties, and strength even when thinned.

[0008] Fig. 1 is an internal perspective view showing an enlarged schematic view of the structure of the composite membrane. Fig. 2 is an SEM photograph (a drawing substitute photograph) of the nanofiber nonwoven fabric obtained in Example 13.

[0009] 1 composite membrane, 10 nanofibers, 20 matrix

[0010] The present invention will be described in detail below. <Matrix Material> First, the matrix material of the present invention will be described. The matrix material of the present invention is used in a composite membrane containing nanofibers and a matrix material, and contains a polymer compound containing sulfonic acid groups and / or phosphonic acid groups in the main chain and / or side chain. As shown in FIG. 1 , a composite membrane 1 comprises a plurality of entangled nanofibers 10 and a matrix 20 made of a matrix material that fills the gaps between the nanofibers 10 and surrounds the nanofibers 10. The matrix material of the present invention is used to form the matrix 20 in such a composite membrane. The matrix material will be described in further detail below.

[0011] [Polymer Compound] The polymer compound used as a matrix material in the present invention has a sulfonic acid group and / or a phosphonic acid group. The polymer compound used in the present invention is preferably a fluorine-free compound. The polymer compound has units containing acidic groups or the like, into which sulfonic acid groups and / or phosphonic acid groups have been introduced. It is also possible to include a -C- group for linking units as a component of the main chain skeleton. That is, in the polymer compound of the present invention, the "main chain skeleton" includes not only skeletons formed by -C-C- bonds, but also those in which such carbon is formed as part of a substituent. Specifically, heterocyclic substituents and the like having the carbon that constitutes the main chain as a component, as shown in the example of the chemical formula below, are also groups that form the main chain skeleton. Furthermore, the main chain skeleton of the polymer compound preferably contains a low-reducing group, specifically a >C=O group (a ketone-containing substituent such as a ketone group) or a substituent having a C=O structure. When a ketone-containing substituent is present, the ketonization rate (the ratio of the number of ketone-containing substituent units to other units) is preferably 1 to 50%, more preferably 10 to 35%, and particularly preferably 10 to 30%. The polymer compound preferably further contains a nitrogen-containing compound group. Examples of the nitrogen-containing compound group include substituents having an isatin skeleton, such as the substituents shown below. While the examples shown below show examples in which the benzene ring and the sulfonic acid group or phosphonic acid group are directly bonded, a spacer group such as an alkylene group may be contained between the benzene ring and the sulfonic acid group or phosphonic acid group. The wavy lines indicate that the carbon atoms constituting each example may constitute the main chain skeleton.

[0012]

[0013] Furthermore, the polymer compound may be composed solely of sulfonic acid group-containing units, but it can also be a copolymer containing sulfonic acid group-containing units and hydrocarbon units that do not contain sulfonic acid groups. When a copolymer is formed, the content of the hydrocarbon units that do not contain sulfonic acid groups is preferably 1 to 50%, more preferably 10 to 35%, and particularly preferably 10 to 30%, in terms of unit ratio. Here, the hydrocarbon units preferably have a low-reducing group in the main chain skeleton, specifically a >C═O group (a ketone-containing substituent such as a ketone group), a substituent having a C═O structure, or even one that further contains an aromatic group in addition to these. Specific examples include the following. Note that the following chemical formulas also show units containing a sulfonic acid group-containing group, but the hydrocarbon units refer to the portion excluding the group containing the sulfonic acid group or phosphonic acid group. That is, in the present invention, the polymer compound preferably has a low-reducing group such as a ketone-containing substituent and a sulfonic acid group and / or a phosphonic acid group. In addition to these, it is preferable that the compound has a nitrogen-containing compound group such as an isatin skeleton.

[0014]

[0015] Specific examples of the polymer compound include the following polymers, which may be used alone or in combination of two or more.

[0016]

[0017]

[0018]

[0019]

[0020]

[0021] The names (abbreviations) of the compounds are listed below their chemical formulas. For example, in the name s[Is-PTP](PTP-BPDC)X_90-10 (X = 1), the 90-10 indicates a 90:10 molar ratio of isatin units to ketone units (the moiety derived from biphenyldicarboxylic acid). This also indicates the molar ratio of each unit in other compounds. Furthermore, in [pIs-sPTP], the ratio of sulfonic acid to phosphonic acid is 50:50 (molar ratio). The presence of an s before the brackets or the abbreviation of each unit indicates the introduction of a sulfonic acid group. For example, if sulfonic acid is introduced into isatin and p-terphenyl, the compound should be written as sIs-sPTP, but for ease of reading, it is sometimes written in parentheses as s[Is-PTP]. The type of parentheses varies depending on whether the compound was sulfonated with concentrated sulfuric acid or fuming sulfuric acid. For example, if isatin is only phosphonated and p-terphenyl is only sulfonated with fuming sulfuric acid, it is represented as [pIs-sPTP] (s[pIs-PTP] means that sulfonic acid is also introduced into the phosphonated isatin unit). [pIs-sPTP]s[Is-PTP]_20-80 indicates that the molar ratio of isatin with sulfonic acid introduced to isatin with phosphonic acid introduced (assuming that all ion exchange groups have been introduced) is 20:80 (the ratio of sulfonic acid to phosphonic acid is 90:10). s[Is-PTP]p(MTP-Is)1_82-18: indicates that the molar ratio of isatin with sulfonic acid introduced to isatin with phosphonic acid introduced (assuming that all ion exchange groups have been introduced) is 82:18 (the ratio of sulfonic acid to phosphonic acid is 73:27). In [pIs-sPTP]p(Is-MTP)_40-60, the ratio of sulfonic acid-introduced PTP to phosphonic acid-introduced MTP (assuming that all ion exchange groups are introduced) is 40:60 (the ratio of sulfonic acid to phosphonic acid is 20:80).In the above examples, for convenience, each unit is described as forming a block, but in reality, each unit may be randomly copolymerized. In the above formula, n represents a number from 1 to 2000, y represents a number from 1 to 2000, z represents a number from 1 to 2000, x represents a number from 1 to 2000, m represents a number from 1 to 2000, and a represents a number from 0 to 1. Furthermore, R represents a hydrogen atom, an alkyl group, or the like. The average molecular weight of the polymer compound is preferably a weight-average molecular weight of 2000 to 1,000,000. (Method for Producing Polymer Compound) The polymer compound used as a matrix material can be produced simply and easily using conventional methods. It has a simple structure that can be produced with a few steps, especially when it contains a unit containing a low-reducing group. Details of the production method will be described in the examples below. The sulfonation of the polymer compound is carried out by reacting CF3 in a solvent such as dichloromethane. ３ SO ３ Although sulfonation can be carried out using a sulfonating agent such as H, in the present invention, a sulfonation method using concentrated sulfuric acid or fuming sulfuric acid and reacting for 1 to 50 hours at a temperature of 100°C or less can also be used. The use and effects will be explained in the section on the manufacturing method of the composite membrane and the use and effects described below. [Other Components] In the present invention, various components other than the polymer compound can be added as the matrix material within the scope of the present invention.

[0022] <Nanofibers> In the present invention, the nanofibers used in combination with the matrix material are nanofibers formed using a nanofiber polymer compound, and nanofibers formed using a polymer compound containing sulfonic acid substituents and / or phosphonic acid substituents are particularly preferred. Furthermore, in the present invention, nanofibers can also be used that are obtained by forming nanofibers from a nanofiber polymer compound and then doping it with an acidic substance. That is, in the present invention, the nanofibers may be doped with an acid component. Examples of polymers that can be used as the nanofiber polymer compound include basic polymers such as polybenzimidazole (PBI) and polyvinyl alcohol (PVA), as shown below. Two or more of these may be mixed together when used. In the present invention, when a composite membrane (electrolyte membrane) is prepared using the polymer compound as a matrix material, PVA is preferred as the nanofiber polymer compound for the nanofibers used in combination. Examples of the nanofiber polymer compound containing the sulfonic acid and / or phosphonic acid substituents include the polymer compounds shown below and the polymer compound components described above, and two or more of these may be used in combination. The nanofiber polymer compound containing the sulfonic acid and / or phosphonic acid substituents and the basic polymer may be used separately, or both may be used in combination. When used in combination, the preferred blend ratio is 10 to 1,000 parts by weight of the basic polymer per 100 parts by weight of the nanofiber polymer compound containing the sulfonic acid and / or phosphonic acid substituents. The acidic substance used in the above-mentioned doping is preferably a sulfonic acid compound or a phosphonic acid compound, such as phytic acid described below. The doping amount of the sulfonic acid compound or phosphonic acid compound is preferably 1 to 20 parts by weight per 100 parts by weight of the total nanofiber weight. [Nanofiber Shape] The nanofiber of the present invention preferably has a fiber diameter of 500 nm or less, more preferably 100 to 400 nm, a fiber length of 50 μm or more, and an aspect ratio of 100 or more. The production method will be explained below in the section on the production method of the composite membrane.

[0023] <Composite membrane (electrolyte membrane)> The composite membrane 1 of this embodiment (see FIG. 1) contains both the matrix material of the present invention and the nanofibers of the present invention. However, there is no limitation thereto, and it is sufficient to contain either one. (Nanofiber assembly (nonwoven fabric)) The nanofibers 10 form a nonwoven fabric layer. In this nonwoven fabric layer, it is preferable that the porosity of the nonwoven fabric itself before filling with the matrix material is 70 to 95% in terms of proton conductivity and membrane strength and gas barrier properties when made into a composite membrane. In particular, using a nonwoven fabric made from nanofibers having the above-mentioned fiber diameters with a porosity within this range is preferable in terms of achieving the desired effects of the present invention. Measurement of porosity will be described later. As will be explained in the manufacturing method described later, a nonwoven fabric is first produced from nanofibers, and then a matrix material is added to the nanofiber nonwoven fabric obtained after a surface modification step, and the nonwoven fabric is immersed in a solution of the matrix material, or a solution of the matrix material is poured into the nonwoven fabric and molded into a desired shape. Here, the porosity refers to the proportion of spaces present between the nanofibers in the state of the nonwoven fabric before immersion in the solution. In other words, the porosity is the proportion of the spaces to the volume of a virtual solid circumscribing the nonwoven fabric, and is expressed as (total volume of the spaces / volume of the virtual solid) x 100.

[0024] (Composition Ratio) The specific composition ratio is preferably 300 to 2,000 parts by weight of matrix material per 100 parts by weight of the nanofibers, and more preferably 400 to 1,000 parts by weight of matrix material per 100 parts by weight of the nanofibers. Outside this range, the composite membrane will not perform adequately as an electrolyte membrane, for example. Therefore, it is preferable to maintain the composition ratio within this range. (Quantitative Ratio Relationship) The proportion of the matrix material relative to the entire composite membrane is sufficient to fill the voids present between the nanofibers at the above porosity and form the outer shape of the composite membrane. However, the proportion is preferably 10 to 95% by weight, more preferably 20 to 90% by weight, and most preferably 30 to 90% by weight, where the total amount including the nanofibers is taken as 100. If the proportion is less than 5% by weight, the matrix material will not fill the nanofiber voids sufficiently, resulting in reduced proton conductivity and gas barrier properties. If the proportion exceeds 90% by weight, the effects of the nanofibers will not be fully realized. (Configuration) The composite membrane of the present invention contains the nanofibers of the present invention described above, the presence ratio of the nanofibers satisfies the quantitative ratio relationship described below, and the thickness is 30 μm or less, more preferably 10 μm or less, even more preferably 8 μm or less, and most preferably 2 μm or less. By satisfying this thickness range, the thickness required in recent years can be satisfied.

[0025] (Other Components) In addition to the above-mentioned components, various additives can be added to the composite membrane of the present invention as long as they do not impair the spirit of the present invention. For example, inorganic particles such as silica particles may be included to improve the mechanical properties of the composite membrane. The particle size of the inorganic particles is preferably 1 nm to 1 μm to maintain the uniformity of the membrane, more preferably 100 nm or less, and even more preferably 20 nm or less.

[0026] <Manufacturing Method> Next, a method for manufacturing the composite membrane will be described. The manufacturing method described below is preferably a method for manufacturing the composite membrane of the present invention, and can be carried out by carrying out a nonwoven fabric forming step of forming a nonwoven fabric made of nanofibers, and a membrane forming step of filling voids in the nonwoven fabric with a matrix material to integrate the nanofibers and the matrix material.

[0027] (Nonwoven Fabric Formation Process) This process produces nanofibers and a nanofiber nonwoven fabric at the same time. This process can be carried out by first dissolving the polymer (such as the sulfonated polymer) that is the raw material for the nanofibers in a solvent, and then discharging the resulting spinning solution onto a collector using a discharger. This process allows the formation of nanofibers before doping and the formation of a nanofiber assembly (nonwoven fabric). The production of fine fiber nonwoven fabrics using a discharger is disclosed, for example, in JP 2003-73964 A, JP 2004-238749 A, and JP 2005-194675 A. This process can be carried out using the methods disclosed therein. Examples of the solvent include dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone (NMP). The raw polymer concentration is preferably 1 to 30% by mass, more preferably 5 to 20% by mass. The viscosity of the spinning solution is preferably 100 to 10,000 mPa·s, more preferably 500 to 5,000 mPa·s. The thickness of the resulting nonwoven fabric is preferably less than 30 μm from the viewpoint of reducing the overall thickness of the composite membrane, more preferably 20 μm or less, and even more preferably 10 μm or less. It is most preferably 2 μm or less. The resulting nonwoven fabric is then doped to obtain the nanofibers of the present invention. The doping can be performed by placing the resulting nonwoven fabric in a container, injecting an acidic substance-containing solution into the container from a separate injection container, immersing the nonwoven fabric for a certain period of time, and then washing with a solvent such as pure water. The concentration of the acidic substance-containing solution is preferably 0.5 to 70% by mass, preferably 1 to 50% by mass, within a range where the solution viscosity is not too high, i.e., 500 mPa·s or less. The immersion conditions are preferably a temperature of 15 to 80° C. and a time of 0.25 to 3 hours, and after each immersion, washing is preferably carried out to remove excess acidic substances.In particular, in the composite membrane of the present invention, since the acidic substance is bound or adsorbed to the nanofibers as described above, it is preferable to remove the excess unbound acidic substance from the viewpoints of membrane strength and gas barrier properties, and furthermore, from the viewpoint of preventing catalyst poisoning when used as a polymer composite membrane for fuel cells. Furthermore, even if the excess acidic substance is removed, sufficient proton conductivity is maintained due to the presence of the molecularly modified surface sites that are bound or otherwise present, so there is no problem. Washing is preferably performed using a cleaning solution such as water at 15 to 80°C for 0.25 to 24 hours. The doped amount of acidic substance (amount adsorbed to the nanofibers) can be calculated by measuring the mass change or ion exchange capacity of the nonwoven fabric before and after doping. To measure the weight change, it is preferable to wash away the excess acidic substance and then thoroughly dry the nonwoven fabric, for example by vacuum drying at 50 to 150°C for 5 to 24 hours.

[0028] (Membrane Formation Process) In this process, the nonwoven fabric made of nanofibers obtained in the previous process is placed in a container, a matrix material solution is poured into the container from a separate injection container, and the nonwoven fabric is immersed in the solution. The solvent used in the matrix material solution is optional depending on the matrix material used, but examples include water, methanol, ethanol, 2-propanol, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), and 2-methoxyethanol. Other solvents may also be used in combination. The matrix material concentration in the solution is preferably 2 to 20% by mass. After immersion, the composite membrane of the present invention can be obtained by evaporating the solvent. Evaporation of the solvent can be achieved, for example, by natural drying at 15 to 150°C, vacuum drying, or treatment in a hot air oven for 1 to 48 hours. In order to stabilize the polymer, the matrix material may be converted into a salt and then treated as the solution. In this case, it is preferable to subject the resulting composite membrane to an acid treatment after the evaporation treatment.

[0029] (Step of Post-treating the Nanofiber-Containing Composite Membrane) By post-treating the obtained nanofiber-containing composite membrane, it is possible to expect effects such as removing remaining solvent and small molecules, exchanging the counter ions of the acid functional groups for protons, and densifying the membrane to improve its stability and gas barrier properties. Post-treatments mainly include solution treatment and heat treatment. Examples of substances used in solution treatment include aqueous hydrogen peroxide solution, aqueous hydrochloric acid solution, aqueous nitric acid solution, ethanol / hydrochloric acid mixed solution, and ethanol / nitric acid mixed solution. After the solution treatment is complete, heat treatment can be performed, such as by vacuum drying at 50 to 150°C for 1 to 48 hours.

[0030] <Use Modes and Advantages> The composite membrane of the present invention can be used as a polymer electrolyte membrane for a polymer electrolyte fuel cell, sandwiched between a positive electrode and a negative electrode. That is, it can be used as a membrane electrode assembly for a polymer electrolyte fuel cell, and in turn, as a polymer electrolyte fuel cell. The composite membrane of the present invention is a thin film as described above, and can stably conduct protons generated at the negative electrode to the positive electrode. Furthermore, the composite membrane of the present invention exhibits high proton conductivity at 90% RH. For this reason, it can also be used as a water electrolysis membrane. Such polymer electrolytes have low membrane resistance (membrane resistance (Ω cm ２ ) = membrane thickness (cm) / proton conductivity (s / cm): s = 1 / Ω) is required, but the composite membrane of the present invention has excellent membrane resistance (for example, 0.58 Ω cm) particularly under high temperature and low humidity conditions (80°C, 30% RH). ２ ) is preferable. In addition, it is preferable that the gas barrier property is high, that is, the gas permeation flow rate is low (O ２ : <1.3 × 10 at 80 ° C and 95% RH －９ (cm ３ / (cm ２.·sec·kPa). In addition, high membrane stability (chemical, mechanical, and thermal) is also required, and the composite membrane of the present invention is expected to satisfy these performance requirements even when its thickness is thinner than conventional membranes. The reason why the composite membrane of the present invention is a well-balanced composite membrane that has low membrane resistance and high gas barrier properties even when thinner than conventional composite membranes is unclear, but the following reasons are thought to be the case. The composite membrane of the present invention configured in this manner not only exhibits the effect of achieving an excellent balance of the above-mentioned performances, but also contains no free acidic substances, preventing poisoning of the platinum catalyst by acidic substances in fuel cells (water electrolysis cells when used for water electrolysis), thereby significantly suppressing deterioration in performance. The density of the fine fibers can be increased by pressing the nonwoven fabric using a hot press or the like, enabling even thinner membranes to be made. The composite membrane of the present invention can be used as an electrolyte membrane for fuel cells, as described below, and also as an aqueous electrolyte membrane for water electrolysis devices.

[0031] [Solid polymer fuel cell] The solid polymer fuel cell of the present invention is characterized by including the above-mentioned composite membrane of the present invention as an electrolyte membrane. Except for the inclusion of the above-mentioned composite membrane of the present invention, it can be configured in the same way as a normal fuel cell. It can also be manufactured in the same way as a normal fuel cell manufacturing method. [Water electrolyzer] The composite membrane of the present invention can also be used in a water electrolyzer. It includes the above-mentioned composite membrane of the present invention as a water electrolysis membrane. Except for the inclusion of the above-mentioned composite membrane of the present invention, it can be configured in the same way as a normal water electrolysis device. It can also be manufactured in the same way as a normal water electrolysis device manufacturing method. Note that the present invention is not limited to the above-mentioned embodiment and can be modified in various ways without departing from the spirit of the present invention.

[0032] EXAMPLES The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these examples at all.

[0033] <Polymer Compound Production Examples> [Production Example 1] Synthesis of Is-PTP 0.986 g (6.70 mmol) of isatin and 1.289 g (5.60 mmol) of p-terphenyl were dissolved in 7.2 mL of dichloromethane (DCM) and CF ３ SO ３ 2.96 mL (33.5 mmol) of HCl was added and stirred at room temperature for 2 hours. The mixture was then reprecipitated in methanol to recover the solid, which was then washed with methanol and vacuum dried at 80°C for 12 hours to obtain the target product (polymer compound). [Production Example 2] Synthesis of (Is-PTP)(PTP-BPDC)1_90-10 0.691 g (3.00 mmol) of p-terphenyl and 0.084 g (0.30 mmol) of 4,4'-biphenyldicarbonyl chloride were dissolved in 4.7 mL of DCM, and CF ３ SO ３ 1.57 mL (17.70 mmol) of HCl was added and stirred at room temperature for 3 hours. Next, 0.477 g (3.24 mmol) of isatin was added and stirred for 2.5 hours, after which the solid was reprecipitated in methanol to recover the solid, which was then washed with methanol and dried in vacuum at 80°C for 12 hours to obtain the target product (polymer compound). [Production Example 3] Synthesis of (Is-PTP)(PTP-BPDC)1_80-20 In Production Example 2, 0.167 g (0.60 mmol) of 4,4'-biphenyldicarbonyl chloride, 4.6 mL of DCM, and CF ３ SO ３ The target product (polymer compound) was obtained by synthesizing in the same manner as in Production Example 2, except that the amount of H was changed to 1.54 mL (17.40 mmol) and the amount of isatin was changed to 0.424 g (2.88 mmol). [Production Example 4] Synthesis of (Is-PTP)(PTP-BPDC)1_70-30: In Production Example 2, 0.251 g (0.90 mmol) of 4,4'-biphenyldicarbonyl chloride, 4.5 mL of DCM, and CF ３ SO ３The target product (polymer compound) was obtained by synthesizing the compound in the same manner as above, except that the amount of H was changed to 1.51 mL (17.10 mmol) and the amount of isatin was changed to 0.371 g (2.52 mmol). [Production Example 5] Synthesis of (Is-PTP)(PTP-BPDC)2_70-30 0.311 g (1.35 mmol) of p-terphenyl and 0.251 g (0.9 mmol) of 4,4'-biphenyldicarbonyl chloride were dissolved in 4.5 mL of DCM, and the resulting mixture was cooled to 50°C. ３ SO ３ 1.51 mL (17.10 mmol) of H was added and the mixture was stirred at room temperature overnight. Next, 0.380 g (1.65 mmol) of p-terphenyl was added and the mixture was stirred for 0.5 hours, and then 0.371 g (2.52 mmol) of isatin was added and the mixture was stirred for 2.5 hours. The mixture was reprecipitated in methanol to recover a solid, which was washed with methanol and then vacuum-dried at 80°C for 12 hours to obtain the target product (polymer compound).

[0034] [Production Example 6] Synthesis of (Is-PTP)(PTP-BPDC)3_70-30 0.276 g (1.20 mmol) of p-terphenyl and 0.251 g (0.90 mmol) of 4,4'-biphenyldicarbonyl chloride were dissolved in 4.5 mL of DCM, and CF ３ SO ３ 1.51 mL (17.10 mmol) of H was added and stirred at room temperature overnight. Next, 0.415 g (1.80 mmol) of p-terphenyl was added and stirred for 0.5 hours, after which 0.371 g (2.52 mmol) of isatin was added and stirred for 2.5 hours. The solid was recovered by reprecipitation in methanol, washed with methanol, and then vacuum dried at 80°C for 12 hours to obtain the target product (polymer compound). [Production Example 7] Synthesis of (Is-BP)(PTP-BPDC)1_65-35 0.484 g (2.10 mmol) of p-terphenyl and 0.293 g (1.05 mmol) of 4,4'-biphenyldicarbonyl chloride were dissolved in 4.5 mL of DCM, and CF ３ SO ３1.50 mL (16.95 mmol) of H was added and stirred at room temperature overnight. Next, 0.139 g (0.90 mmol) of biphenyl was added and stirred for 0.5 hours, and then 0.344 g (2.34 mmol) of isatin was added and stirred for 2.5 hours. The solid was recovered by reprecipitation in methanol, washed with methanol, and then vacuum dried at 80°C for 12 hours to obtain the target product (polymer compound). [Production Example 8] Synthesis of (Is-PQP)(PTP-BPDC)1_70-30: In Production Example 7, 0.415 g (1.80 mmol) of p-terphenyl, 0.251 g (0.90 mmol) of 4,4'-biphenyldicarbonyl chloride, 4.5 mL of DCM, and CF ３ SO ３ A polymer compound was obtained by synthesizing the compound in the same manner as above, except that the amount of H was changed to 1.51 mL (17.10 mmol), the amount of biphenyl to 0.367 g (1.20 mmol), and the amount of isatin to 0.371 g (2.52 mmol). [Production Example 9] Synthesis of (Is-PTP / TPE)(PTP-BPDC)1_70(10 / 90)-30 0.311 g (1.35 mmol) of p-terphenyl and 0.126 g (0.45 mmol) of 4,4'-biphenyldicarbonyl chloride were dissolved in 2.2 mL of DCM, and CF ３ SO ３ 0.78 mL (8.55 mmol) of H was added and stirred at room temperature for 3 hours. Next, 0.054 g (0.15 mmol) of 1,2-bis(p-toluyl)-1,2-diphenylethylene and 0.185 g (1.26 mmol) of isatin were added and stirred for 16 hours. The solid was recovered by reprecipitation in methanol, washed with methanol, and then vacuum dried at 80°C for 12 hours to obtain the target product (polymer compound). [Production Example 10] Synthesis of (Is / PhIs-PTP)(PTP-BPDC)1_65(67 / 33)-35 0.691 g (3.00 mmol) of p-terphenyl and 0.293 g (1.05 mmol) of 4,4'-biphenyldicarbonyl chloride were dissolved in 4.5 mL of DCM, and CF ３ SO ３1.50 mL (16.95 mmol) of H was added and stirred at room temperature for 3 hours. Next, 0.191 g (1.30 mmol) of isatin and 0.145 g (0.65 mmol) of 1-phenylisatin were added and stirred for 16 hours. The solid was recovered by reprecipitation in methanol, washed with methanol, and then vacuum dried at 80°C for 12 hours to obtain the target product (polymer compound).

[0035] [Production Example 11] Synthesis of (Is / Py-PTP)(PTP-BPDC)1_90(75 / 25)-10 0.691 g (3.00 mmol) of p-terphenyl and 0.084 g (0.30 mmol) of 4,4'-biphenyldicarbonyl chloride were dissolved in 1.5 mL of DCM, and CF ３ SO ３ 1.59 mL (18.00 mmol) of H was added and stirred at room temperature for 3 hours. ３ 0.1 mL of COOH was added and stirred at room temperature for several minutes, after which 0.221 g (1.50 mmol) of isatin was added. The initially prepared solution was then added, followed by 2.5 mL of DCM, and the mixture was stirred at room temperature for 16 hours. The solid was recovered by reprecipitation in methanol, washed with methanol, and then vacuum dried at 80°C for 12 hours to obtain the target product (polymer compound). [Production Example 12] Synthesis of (Is-BPNL / PTP)(PTP-BPDC)1_70-30 0.242 g (1.05 mmol) of p-terphenyl and 0.088 g (0.33 mmol) of 4,4'-biphenyldicarbonyl chloride were dissolved in 1.3 mL of nitrobenzene, and CF ３ SO ３0.75 mL (8.48 mmol) of H was added and stirred at room temperature overnight. Next, 0.078 g (0.42 mmol) of 2,2'-dihydroxybiphenyl was added and stirred for 0.5 hours, after which 0.170 g (1.16 mmol) of isatin was added and stirred for 16 hours. The solid was recovered by reprecipitation in methanol, washed with methanol, and then vacuum dried at 80°C for 12 hours to obtain the target product (polymer compound). [Production Example 13] Synthesis of (BPDC-DMB) (BPDC-PTP)_90-10 0.0184 g (0.08 mmol) of p-terphenyl, 0.154 g (0.72 mmol) of 2,2'-dimethoxybiphenyl, and 0.223 g (0.80 mmol) of 4,4'-biphenyldicarbonyl chloride were mixed with CF ３ SO ３ 1.59 mL (18.00 mmol) of H was added, and the mixture was stirred at room temperature for 96 hours. The solid was then reprecipitated in methanol to recover the solid, which was washed with methanol and then vacuum dried at 80°C for 12 hours to obtain the target compound. [Production Example 14] Synthesis of (BPDC-BPNL) (BPDC-PTP)_90-10 A polymer compound was obtained by synthesis in the same procedure as in Production Example 13, except that the 2,2'-dimethoxybiphenyl obtained in Production Example 13 was replaced with 0.134 g (0.72 mmol) of 2,2'-biphenol, and the reaction conditions were changed to 40°C and stirring for 24 hours.

[0036] [Production Example 15] Synthesis of (TPC / BPDC-BPNL) (BPDC-PTP) 70-30 0.051 g (0.22 mmol) of p-terphenyl, 0.164 g (0.88 mmol) of 2,2'-biphenol, 0.122 g (0.44 mmol) of 4,4'-biphenyldicarbonyl chloride, and 0.134 g (0.66 mmol) of terephthalic acid dichloride were mixed together to prepare CF ３ SO ３ 2.21 mL (25.00 mmol) of H was added and the mixture was allowed to react at 40°C for 7 hours. The solid was then reprecipitated in methanol, recovered, washed with methanol, and vacuum dried at 80°C for 12 hours to obtain the target product (polymer compound). [Production Example 16] Synthesis of BrIs-PTP 0.542 g (2.40 mmol) of 5-bromoisatin and 0.461 g (2.00 mmol) of p-terphenyl were dissolved in 3.2 mL of DCM, and CF３ SO ３ 1.06 mL (12.00 mmol) of HCl was added and stirred at room temperature overnight. The mixture was then reprecipitated in methanol to recover the solid, which was then washed with methanol and vacuum dried at 80°C for 12 hours to obtain the target product (polymer compound). [Production Example 17] Synthesis of (Is-PTP)(PTP-BrIs)1_80-20 0.461 g (2.00 mmol) of p-terphenyl and 0.090 g (0.40 mmol) of 5-bromoisatin were dissolved in 3.0 mL of DCM, and CF ３ SO ３ 1.06 mL (12.00 mmol) of HCl was added and stirred at room temperature for 0.5 hours. 0.294 g (2.00 mmol) of isatin was then added and stirred for 1 hour, after which the solid was reprecipitated in methanol to recover, washed with methanol, and vacuum dried at 80°C for 12 hours to obtain the target product (polymer compound). [Production Example 18] Synthesis of (Is-PTP)(BrMTP-BrIs)1_82-18 0.226 g (1.00 mmol) of 5-bromoisatin and 0.618 g (2.00 mmol) of 5'-bromo-m-terphenyl were dissolved in 9.0 mL of DCM, and CF ３ SO ３ 4.83 mL (54.60 mmol) of H was added and stirred at room temperature for 1.5 hours. Next, 0.803 g (5.46 mmol) of isatin and 0.817 g (3.55 mmol) of p-terphenyl were added and stirred for 3 hours. The solid was recovered by reprecipitation in methanol, washed with methanol, and then vacuum dried at 80°C for 12 hours to obtain the target product (polymer compound).

[0037] [Production Example 19] Synthesis of (BrIs-PTP) (BrIs-BrMTP) 40-60 0.276 g (1.20 mmol) of p-terphenyl and 0.557 g (1.80 mmol) of 5'-bromo-m-terphenyl were dissolved in 4.8 mL of DCM, and CF ３ SO ３1.59 mL (18.00 mmol) of HCl and 0.813 g (3.60 mmol) of 5-bromoisatin were added and stirred at room temperature for 12 hours. The solid was then reprecipitated in methanol, recovered, washed with methanol, and vacuum dried at 80°C for 12 hours to obtain the target compound. [Production Example 20] Synthesis of (BrIs / Is-PTP)(PTP-BPDC)1 0.415 g (1.80 mmol) of p-terphenyl and 0.151 g (0.54 mmol) of 4,4'-biphenyldicarbonyl chloride were dissolved in 2.4 mL of DCM, and CF ３ SO ３ 0.80 mL (9.00 mmol) of H was added and stirred overnight at room temperature. Next, 0.095 g (0.42 mmol) of 5-bromoisatin and 0.124 g (0.84 mmol) of isatin were added and stirred for 16 hours. The solid was recovered by reprecipitation in methanol, washed with methanol, and then vacuum dried at 80°C for 12 hours to obtain the target product (polymer compound). [Production Example 21] Phosphonation of the compound obtained in Production Example 16 (synthesis of pIs-PTP) 0.44 g of the polymer obtained in Production Example 16 was dissolved in 2.5 mL of DMAc under a nitrogen atmosphere, and then 2.58 mL (20.00 mmol) of diethyl phosphite, 2.78 mL (20.00 mmol) of triethylamine, Pd(PPh ３ ) ４ 0.347 g (0.30 mmol) of bromotrimethylsilane was added and the mixture was stirred at 100°C for 16 hours. After the reaction was completed, the solid was recovered by reprecipitation in methanol, washed with methanol, and then dried in vacuum at room temperature for 12 hours to obtain a phosphonate ester polymer. The obtained polymer was dissolved in 2.5 mL of DMAc, and then 0.78 mL (6.00 mmol) of bromotrimethylsilane was added and the mixture was stirred at room temperature for 16 hours. The solid was recovered by reprecipitation in methanol, washed with methanol, and then dried in vacuum at room temperature for 12 hours to obtain a phosphonate polymer (polymer compound). [Production Example 22] Phosphonation of the compound obtained in Production Example 17 (synthesis of s[Is-PTP][sPTP-pIs]1_80-20) 0.75 g of the polymer obtained in Production Example 17 was dissolved in 4.0 mL of DMAc under a nitrogen atmosphere, and then 0.52 mL (4.00 mmol) of diethyl phosphite, 0.56 mL (4.00 mmol) of triethylamine, Pd(PPh３ ) ４ 0.116 g (0.10 mmol) of bromotrimethylsilane was added and the mixture was stirred at 100°C for 16 hours. After the reaction was completed, the solid was recovered by reprecipitation in methanol, washed with methanol, and then dried in vacuum at room temperature for 12 hours to obtain a phosphonate ester polymer. The obtained polymer was dissolved in 4.0 mL of DMAc, and then 0.16 mL (1.20 mmol) of bromotrimethylsilane was added and the mixture was stirred at room temperature for 16 hours. The solid was recovered by reprecipitation in methanol, washed with methanol, and then dried in vacuum at room temperature for 12 hours to obtain a phosphonate polymer (polymer compound).

[0038] [Production Example 23] Phosphonation of the compound obtained in Production Example 18 (synthesis of (Is-PTP)p(MTP-Is)1_82-18) Synthesis was performed in the same manner as in Production Example 22, except that 0.30 g of the polymer obtained in Production Example 18 was used instead of the polymer obtained in Production Example 17, and the amounts of DMAc used to initially dissolve the polymer and to redissolve the obtained polymer were each 1.5 mL, to obtain a phosphonate polymer (polymer compound). [Production Example 24] Phosphonation of the compound obtained in Production Example 19 (synthesis of (pIs-PTP)p(Is-MTP)_40-60) Synthesis was performed in the same manner as in Production Example 21, except that 0.60 g of the polymer obtained in Production Example 19 was used instead of the polymer obtained in Production Example 16, and the amounts of DMAc used to initially dissolve the polymer and to redissolve the obtained polymer were each 4.0 mL, to obtain a phosphonate polymer (polymer compound). [Production Example 25] Sulfonation with Concentrated Sulfuric Acid: 0.4 g of each of the polymer compounds obtained in Production Examples 1, 8, and 23 was placed in a single-neck flask. 20.0 mL of concentrated sulfuric acid was added, and the mixture was stirred at 50°C for 3 or 24 hours. The solid was then reprecipitated in water to recover the solid. The resulting solid was washed multiple times with water and vacuum-dried at room temperature for 24 hours to obtain a sulfonic acid polymer (polymer compound). The reaction time for the polymer compounds obtained in Production Examples 1 and 8 was 3 hours, and the reaction time for the polymer compound obtained in Production Example 23 was 24 hours. In tables and elsewhere, sulfonation using concentrated sulfuric acid is indicated by s{...}. [Production Example 26] Sulfonation with Oleum: 0.4 g of each of the polymer compounds obtained in Production Examples 1 to 15 and 20 to 24 was placed in a single-neck flask. 8.0 mL of fuming sulfuric acid (30%) was added, and the mixture was stirred at 40 to 80°C for 3 to 24 hours. The solid was then reprecipitated in ice water to recover the solid. The resulting solid was washed multiple times with water and vacuum dried at room temperature for 24 hours to obtain a sulfonic acid polymer (polymer compound). The polymer compounds obtained in Production Examples 7, 9, and 24 were reacted at a temperature of 50°C for a reaction time of 6 hours, the polymer compounds obtained in Production Examples 12 to 15 were reacted at a temperature of 40°C for a reaction time of 24 hours, the polymer compound obtained in Production Example 23 was reacted at a temperature of 40°C for a reaction time of 3 hours, and the other polymer compounds were reacted at a temperature of 80°C for a reaction time of 24 hours.In tables etc., sulfonation using fuming sulfuric acid is indicated by s[......]. [Production Example 27] Phosphonation of polymer compound obtained by sulfonating the polymer compound obtained in Production Example 20 (synthesis of s[pIs / Is-PTP](PTP-BPDC)1) A phosphonate polymer (polymer compound) was obtained by synthesis in the same manner as in Production Example 22, except that 0.56 g of the polymer obtained in Production Example 20 was sulfonated by the procedure of Production Example 26 was used.

[0039] [Production Example 28] Synthesis of (Is-PTP) (PTP-IPC) 1_70-30 2.764 g (12.0 mmol) of p-terphenyl and 0.731 g (3.60 mmol) of isophthalic acid dichloride were dissolved in 18 mL of DCM, and CF ３ SO ３6.04 mL (68.4 mmol) of HCl was added and stirred at room temperature for 16 hours. Next, 1.483 g (10.1 mmol) of isatin was added and stirred for 6 hours, after which the solid was reprecipitated in methanol to recover, washed with methanol, and dried in vacuum at 80°C for 12 hours to obtain the target product (polymer compound). [Preparation Example 29] Synthesis of (Is / PrP15-PTP)(PTP-IPC)1_70-30 0.20 g of the polymer obtained in Preparation Example 28 was dissolved in 4.0 mL of DMAc, and then 0.011 mL (0.055 mmol) of 3-(bromopropyl)diethyl phosphonate and 0.019 g (0.135 mmol) of potassium carbonate were added and stirred at 100°C for 16 hours. The solid was reprecipitated in 0.1 mol / L aqueous hydrochloric acid to recover, washed with water and methanol, and dried in vacuum at 80°C for 12 hours to obtain a phosphonate ester polymer. The resulting polymer was dissolved in 2.0 mL of DMAc, and then 0.071 mL (0.550 mmol) of bromotrimethylsilane was added and stirred at room temperature for 16 hours. The solid was reprecipitated in methanol, recovered, washed with methanol, and vacuum dried at 40°C for 12 hours to obtain a phosphonic acid polymer (polymer compound). [Production Example 30] Synthesis of (Is / PrP30-PTP)(PTP-IPC)1_70-30 The target product (polymer compound) was obtained by synthesizing in the same procedure as in Production Example 29, except that the amounts of 3-(bromopropyl)diethyl phosphonate were changed to 0.022 mL (0.111 mmol), potassium carbonate to 0.037 g (0.270 mmol), and bromotrimethylsilane to 0.144 mL (1.11 mmol). [Production Example 31] Synthesis of (Is / PrP70-PTP) (PTP-IPC)1_70-30 The target product (polymer compound) was obtained by synthesis following the same procedure as in Production Example 29, except that the amounts of 3-(bromopropyl)diethyl phosphonate were changed to 0.054 mL (0.278 mmol), potassium carbonate to 0.058 g (0.417 mmol), and bromotrimethylsilane to 0.216 mL (1.67 mmol).[Preparation Example 32] Synthesis of (Is / BuS15 / PrP30-PTP)(PTP-IPC)1_70-30 0.20 g of the polymer obtained in Preparation Example 28 was dissolved in 3.0 mL of DMAc, and then 0.007 g (0.290 mmol) of sodium hydride was added. The mixture was stirred at 80°C for 3 hours. 0.006 g (0.056 mmol) of 1,4-butanesultone was then added and the mixture was stirred at 100°C for 16 hours. 0.022 mL (0.111 mmol) of 3-(bromopropyl)diethyl phosphonate and 0.037 g (0.270 mmol) of potassium carbonate were then added and the mixture was stirred at 100°C for 16 hours. The solid was recovered by reprecipitation in 0.1 mol / L aqueous hydrochloric acid, washed with water and methanol, and then vacuum dried at 80°C for 12 hours to obtain a phosphonate ester polymer. The resulting polymer was dissolved in 2.0 mL of DMAc, and then 0.144 mL (1.11 mmol) of bromotrimethylsilane was added and stirred at room temperature for 16 hours. The solid was reprecipitated in methanol, recovered, washed with methanol, and vacuum dried at 40°C for 12 hours to obtain a phosphonic acid polymer (polymer compound). [Production Example 33] Synthesis of (ppIs / Is-PTP)_40-60 0.461 g (2.00 mmol) of p-terphenyl, 0.244 g (0.80 mmol) of 5,7-dibromoisatin, and 0.177 g (1.20 mmol) of isatin were dissolved in 3.0 mL of DCM and 1.06 mL (12.00 mmol) of CF. ３ SO ３ H was added and the mixture was stirred at room temperature for 6 hours. The solid was recovered by reprecipitation in methanol, washed with methanol, and then vacuum dried at 80°C for 12 hours to obtain a polymer. The obtained polymer was dissolved in 5 mL of DMAc under a nitrogen atmosphere, and then diluted with 2.07 mL (16.00 mmol) of diethyl phosphite, 2.22 mL (16.00 mmol), Pd(PPh ３ ) ４0.555 g (0.48 mmol) of bromotrimethylsilane was added and the mixture was stirred at 100°C for 16 hours. After the reaction was completed, the solid was recovered by reprecipitation in methanol, washed with methanol, and then dried in vacuum at room temperature for 12 hours to obtain a phosphonate ester polymer. The obtained polymer was dissolved in 5 mL of DMAc, and then 1.25 mL (9.60 mmol) of bromotrimethylsilane was added and the mixture was stirred at room temperature for 16 hours. The solid was recovered by reprecipitation in methanol, washed with methanol, and then dried in vacuum at 40°C for 12 hours to obtain a phosphonate polymer (polymer compound). [Production Example 34] Synthesis of (ppIs / Is-PTP)_50-50: In Production Example 33, 0.305 g (1.00 mmol) of 5,7-dibromoisatin, 0.147 g (1.00 mmol) of isatin, 2.58 mL (20.00 mmol) of diethyl phosphite, 2.78 mL (20.00 mmol) of triethylamine, and Pd(PPh ３ ) ４ A phosphonic acid polymer (polymer compound) was obtained by synthesizing the polymer compound in the same manner, except that the amount of methyl methyl silane was changed to 0.693 g (0.60 mmol) and bromotrimethylsilane to 1.56 mL (12.0 mmol). [Production Example 35] 0.2 g of each of the polymer compounds obtained in Production Examples 28 to 34 was placed in a single-necked flask. 4 mL of fuming sulfuric acid (30%) was added, and the mixture was stirred at 40°C for 24 hours, after which the solid was reprecipitated in ice water and recovered. The resulting solid was washed multiple times with water and dried in a vacuum at room temperature for 24 hours to obtain a sulfonic acid polymer (polymer compound). The product sulfonated with fuming sulfuric acid is indicated by s [...].

[0040] To evaluate the performance of the polymer compounds obtained in Production Examples 1 to 27 when used as matrix materials, films were produced as follows, and evaluation tests were performed on each. The film thickness of each of the obtained films was approximately 30 μm, as measured by standard methods. [Film Preparation 1 Using the Obtained Polymer Compounds] Film Preparation Using Dimethylformamide (DMAc) or Dimethyl Sulfoxide (DMSO): 0.080 g of each polymer compound was dissolved in 1.0 mL of DMAc or DMSO and spread onto a glass plate to a size of 4 cm x 5 cm. The glass plate was placed in a vacuum dryer and vacuum-dried at 40°C for approximately 3 hours, followed by vacuum drying at 80°C for 3 hours. The film was peeled from the glass plate and immersed in a 3 M aqueous hydrochloric acid solution overnight. The film was then thoroughly washed with water and vacuum-dried at 80°C for 3 hours before being used for evaluation. Films of the sulfonated polymer compounds obtained in Production Examples 5 and 6 were prepared using DMAc, while films of the sulfonated polymer compounds obtained in Production Examples 21 to 24 and the polymer compound obtained in Production Example 27 were prepared using DMSO. [Film Preparation 2 Using Obtained Polymer Compounds] Film Preparation Using 2-Methoxyethanol 0.080 g of each polymer compound was dissolved in 1.5 mL of 2-methoxyethanol and poured into a silicon mold with an inner size of 4 cm x 5 cm placed on a glass plate. The glass plate was placed on a hot plate, heated to 40°C, and thoroughly dried, followed by vacuum drying at 80°C for 3 hours. The obtained film was used for evaluation as is. Films of the polymer compounds other than the polymer compound obtained in Production Example 28 were prepared using 2-methoxyethanol. In the following tables, in the Production Example column, the polymer compound obtained by sulfonating the polymer compound obtained in Production Example 1 with concentrated sulfuric acid is shown as 25-1 (meaning the sulfonated polymer compound of Production Example 1 obtained in Production Example 25), and the polymer compound obtained by sulfonating the polymer compound obtained in Production Example 1 with fuming sulfuric acid is shown as 26-1 (meaning the sulfonated polymer compound of Production Example 1 obtained in Production Example 26). Sulfonated polymer compounds obtained in other Production Examples are shown in the same manner.

[0041] The obtained films were subjected to the following tests and evaluated. The results are shown in Tables 1 to 4. For comparison, a film produced by the above-mentioned production method 1 using the product name "Nafion NR211" was similarly evaluated. The results are also shown in the tables. [Evaluation of ion exchange capacity (IEC)] The obtained polymer compound film was immersed in a 1M NaCl aqueous solution overnight, and after removing the film from the solution, titration was carried out using a 0.01M NaOH aqueous solution to evaluate the ion exchange capacity. Furthermore, for polymers containing phosphonic acid, in addition to the titration results, １ H and ３１ It is possible to evaluate the ion exchange capacity (meq / g) by taking into consideration the results of P NMR measurement. [Proton Conductivity of Various Electrolyte Membranes] Using an Impedance Analyzer 3532-50 (manufactured by Hioki Corporation), the frequency response from 50 kHz to 5 MHz was measured, and the resistance of the electrolyte membrane (electrode distance 1.0 cm) was measured. The temperature and humidity during the resistance measurement were maintained at 80°C, 70% RH, and 80°C, 90% RH, respectively, using a thermo-hygrostat SH-221 (manufactured by ESPEC Corporation). The resistance [Ω], electrode distance [cm], and membrane cross-sectional area [cm] obtained by impedance measurement were used. ２ ], and the formula: electrode distance [cm] / (membrane cross-sectional area [cm ２ ] × resistance [Ω]) to calculate the proton conductivity [mS / cm]. As is clear from the results shown in Tables 1 to 5, all of the above-mentioned polymer compounds constituting the matrix material of the present invention have excellent performance as a matrix material. In each table, an entry such as 26-9 in the Production Example column means that the polymer compound obtained in Production Example 26 was obtained by sulfonating the polymer compound obtained in Production Example 9. The same applies to others.

[0042]

[0043]

[0044]

[0045]

[0046]

[0047] Example 1: Preparation of Phy-PBI-only nanofiber nonwoven fabric / Electrolyte membrane (composite membrane) from Production Example 25-1 An electrolyte membrane was prepared using a PBI-only nanofiber nonwoven fabric and the polymer compound obtained in Production Example 25-1 as the matrix polymer. The mass ratio was set to 10 / 100, taking into consideration porosity and density. The PBI nanofiber nonwoven fabric was prepared by dissolving the raw polymer polybenzimidazole (PBI) in a solvent such as DMAc to obtain a solution. This solution was then electrospinned using a NANON-04 electrospinning device (manufactured by MECC) to obtain a PBI nanofiber nonwoven fabric by adjusting the amount of polymer solution discharged, the distance between the syringe and the collector, and the syringe voltage. The resulting nanofibers were vacuum-dried at 60°C for 15 hours. The PBI nanofiber nonwoven fabric was then modified with an acidic substance. PBI nanofibers were immersed in a phytic acid aqueous solution (50 wt%) at room temperature for 1 hour, then repeatedly washed in pure water at 80°C for a total of 24 hours to remove undoped phytic acid. The phytic acid-modified nanofibers were then vacuum-dried at 60°C for 15 hours. This treatment enabled the modification of only the phytic acid, which exhibits acid-base interaction, on the basic polymer nanofibers. The change in nanofiber weight before and after surface modification revealed that the proportion of molecularly modified sites relative to the entire surface-modified nanofiber was 7.4 mass%. The resulting PBI-only nanofiber nonwoven fabric with a thickness of approximately 30 μm was placed in a glass Petri dish, and a 2-methoxyethanol solution (5 wt%) of the polymer compound obtained in Production Example 25-1 was cast onto it. The solvent was then slowly evaporated in air at room temperature. The electrolyte membrane was then immersed in hydrochloric acid (3 M) at room temperature for 3 hours and washed with pure water. The PBI-only nanofiber nonwoven fabric / Production Example 25-1 electrolyte membrane was then obtained by vacuum-drying at 60°C for 15 hours. The thickness of the electrolyte membrane was about 60 μm.

[0048] Example 2: Preparation of Phy-PBI Pure Nanofiber Nonwoven Fabric / Electrolyte Membrane (Composite Membrane) from Production Example 26-2 An electrolyte membrane was prepared using a PBI pure nanofiber nonwoven fabric and the polymer compound obtained in Production Example 26-2 as the matrix polymer. The mass ratio was set to 10 / 100, taking into account porosity and density. PBI nanofiber nonwoven fabric (obtained in the same manner as in Example 1) was modified with an acidic substance. The PBI nanofiber was immersed in a 50 wt% aqueous phytic acid solution at room temperature for 1 hour, then repeatedly washed in pure water at 80°C for a total of 24 hours to remove undoped phytic acid. The phytic acid-modified nanofiber was vacuum-dried at 60°C for 15 hours. This treatment enabled the modification of only the phytic acid, which interacts with the acid and base, on the basic polymer nanofiber. The change in nanofiber weight before and after surface modification revealed that the proportion of molecularly modified sites relative to the entire surface-modified nanofiber was 4.8 mass%. The resulting PBI-only nanofiber nonwoven fabric, which had a thickness of approximately 29 μm, was placed in a glass petri dish, and a 2-methoxyethanol solution (3 wt %) of the polymer compound obtained in Production Example 26-2 was cast onto it. The solvent was slowly evaporated in air at room temperature. The resulting material was then vacuum-dried at 60°C for 15 hours to obtain the PBI-only nanofiber nonwoven fabric / Production Example 26-2 electrolyte membrane. The electrolyte membrane had a thickness of approximately 49 μm.

[0049] Example 3: Preparation of PBI-only nanofiber nonwoven fabric / Production Example 26-2 electrolyte membrane (composite membrane) An electrolyte membrane was prepared using a PBI-only nanofiber nonwoven fabric and the polymer compound obtained in Production Example 26-2 as a matrix polymer. The mass ratio was set to 10 / 100, taking into consideration porosity and density. A PBI-only nanofiber nonwoven fabric (obtained in the same manner as in Example 1) with a thickness of approximately 29 μm was placed in a glass petri dish, and a 2-methoxyethanol solution (3 wt %) of the polymer compound obtained in Production Example 26-2 was cast onto it. The solvent was slowly evaporated under ambient air at room temperature. The membrane was then vacuum-dried at 60°C for 15 hours to obtain a PBI-only nanofiber nonwoven fabric / Production Example 26-2 electrolyte membrane. The membrane thickness of the electrolyte membrane was approximately 63 μm.

[0050] Example 4: Preparation of Phy-PBI Pure Nanofiber Nonwoven Fabric / Electrolyte Membrane (Composite Membrane) from Production Example 26-4 An electrolyte membrane was prepared using a PBI pure nanofiber nonwoven fabric and the polymer compound obtained in Production Example 26-4 as the matrix polymer. The mass ratio was set to 10 / 100, taking into account porosity and density. PBI nanofiber nonwoven fabric (obtained in the same manner as in Example 1) was modified with an acidic substance. The PBI nanofiber was immersed in a 50 wt% aqueous phytic acid solution at room temperature for 1 hour, then repeatedly washed in pure water at 80°C for a total of 24 hours to remove undoped phytic acid. The phytic acid-modified nanofiber was vacuum-dried at 60°C for 15 hours. This treatment enabled the modification of only the phytic acid, which interacts with the acid and base, on the basic polymer nanofiber. The change in nanofiber weight before and after surface modification revealed that the proportion of molecularly modified sites relative to the entire surface-modified nanofiber was 7.4 mass%. The resulting PBI-only nanofiber nonwoven fabric with a thickness of approximately 30 μm was placed in a glass petri dish, and a 2-methoxyethanol solution (3 wt %) of the polymer compound obtained in Production Example 26-4 was cast onto it. The solvent was then slowly evaporated in the atmosphere at room temperature. The electrolyte membrane was then immersed in hydrochloric acid (3 M) at room temperature for 3 hours and washed with pure water. The membrane was then vacuum dried at 60°C for 15 hours to obtain the PBI-only nanofiber nonwoven fabric / Production Example 26-4 electrolyte membrane. The membrane thickness was approximately 60 μm.

[0051] Example 5: Preparation of SPAES / PBI (20 / 80) Composite Nanofiber Nonwoven Fabric / Production Example 26-4 Electrolyte Membrane (Composite Membrane) Sulfonated polyarylene ether sulfone salt and polybenzimidazole were added to a vial at a weight ratio of 20 / 80, and dehydrated N,N-dimethylacetamide (DMAc) was added so that the polymer weight was 15% by mass of the total weight. The vial was filled with nitrogen and stirred overnight to dissolve the polymer, preparing a polymer solution. Aluminum foil was placed on the collector of an electrospinning device NANON-04 (manufactured by MECC), and a syringe filled with the polymer solution was set to the electrospinning device. Electrospinning was performed with the polymer solution discharge rate set to 0.2 mL / hour. The distance between the syringe and the collector was set to 10 cm, and a voltage of 15 kV was applied to the syringe. This resulted in a SPAES / PBI (20 / 80) composite nanofiber nonwoven fabric being laminated on the aluminum foil. The resulting composite nanofibers were vacuum-dried at 60°C for 15 hours. The resulting composite nanofibers were then post-treated for acid treatment and acid doping. The composite nanofibers were immersed in hydrochloric acid (0.1 M) at room temperature for 3 hours and washed with pure water. Subsequently, they were immersed in a phytic acid aqueous solution (50 wt%) at room temperature for 1 hour, and then repeatedly washed in pure water at 80°C for a total of 24 hours to remove undoped phytic acid. The acid-doped composite nanofibers were vacuum-dried at 60°C for 15 hours. This post-treatment converts the SPAES sodium salt to the proton form and dopes the basic polymer with phytic acid. A portion of the nanofibers was osmium-coated and observed with a scanning electron microscope (SEM, JEOL JSM-6100). The fiber diameter of the nanofibers was calculated from the SEM images. The SEM images confirmed that uniform nanofibers were produced, with a fiber diameter of 156±35 nm. The porosity was determined by cutting the fiber mat into 3 cm squares, and calculating the apparent volume (V) calculated from the dry mass (W) and the film thickness measured with a film thickness meter, and the density of SPAES / PBI (20 / 80) (1.5 g / cm ３) was used to calculate the porosity using the following formula: Porosity (%) = (1 - (W / (V x 1.5)) x 100 The calculated porosity was approximately 89%. The obtained PBI-only nanofiber nonwoven fabric with a thickness of approximately 30 μm was placed in a glass petri dish, and a 2-methoxyethanol solution (3 wt %) of the polymer compound obtained in Production Example 26-4 was cast into it. The solvent was then slowly evaporated in the atmosphere at room temperature. The electrolyte membrane was then immersed in hydrochloric acid (3 M) at room temperature for 3 hours and washed with pure water. The electrolyte membrane was then vacuum dried at 60°C for 15 hours to obtain a SPAES / PBI (20 / 80) composite nanofiber nonwoven fabric / Production Example 26-4 electrolyte membrane. The membrane thickness was approximately 70 μm.

[0052] Example 6: Preparation of PVA-Only Nanofiber Nonwoven Fabric / Production Example 26-2 Electrolyte Membrane (Composite Membrane) Polyvinyl alcohol (PVA) was added to a vial, and distilled water was added so that the polymer weight was 10% by mass of the total weight. After stirring at 150 rpm for 5-10 minutes at room temperature, the mixture was heated and stirred at 150 rpm at 90°C for 1 hour to dissolve the polymer, preparing a polymer solution. Aluminum foil was placed on the collector of an electrospinning device NANON-04 (manufactured by MECC). A syringe filled with the polymer solution after stirring at room temperature for half a day to a day was then attached to the electrospinning device, and electrospinning was performed at a polymer solution release rate of 0.5 mL / hour. The distance between the syringe and the collector was set to 15 cm, and a voltage of 25 kV was applied to the syringe. This resulted in a PVA nanofiber nonwoven fabric being laminated on the aluminum foil. A crosslinking agent for PVA nanofiber nonwoven fabric was prepared by diluting a 50% by weight glutaraldehyde (GA) solution with acetone as a solvent and hydrochloric acid as a catalyst to a 20 mM GA concentration. PVA nanofiber nonwoven fabric was immersed in this crosslinking agent for 1 hour at room temperature, washed with acetone, and then vacuum-dried overnight at 60°C. Acetalization of one GA molecule with four hydroxyl groups in the PVA in an acidic solution allows PVA molecules to be crosslinked by the GA, thereby insolubilizing the readily soluble PVA. A portion of the nanofibers was osmium-coated and observed with a scanning electron microscope (SEM, JEOL JSM-6100). The fiber diameter of the nanofibers was calculated from the resulting SEM images. The SEM images confirmed that uniform nanofibers had been produced, with a fiber diameter of 200 nm. The porosity was determined by cutting the fiber mat into 4 cm squares, and calculating the apparent volume (V) calculated from the dry mass (W) and the film thickness measured with a film thickness meter, and the density of the PVA (1.27 g / cm ３) was used to calculate the porosity using the following formula: Porosity (%) = (1 - (W / (V × 1.27)) × 100 The calculated porosity was approximately 86%. The obtained PVA-only nanofiber nonwoven fabric with a thickness of approximately 31 μm was placed in a glass petri dish, and a 2-methoxyethanol solution (3 wt %) of the polymer compound obtained in Production Example 26-2 was cast onto it, and the solvent was slowly evaporated in air at room temperature. The resultant was then vacuum-dried at 60°C for 15 hours to obtain a PVA-only nanofiber nonwoven fabric / Production Example 26-2 electrolyte membrane. The membrane thickness of the electrolyte membrane was approximately 67 μm.

[0053] Example 7: Preparation of Production Example 26-4 / PBI (20 / 80) Composite Nanofiber Nonwoven Fabric The triethylamine salt of the polymer compound obtained in Production Example 26-4 and polybenzimidazole were added to a vial at a weight ratio of 20 / 80, and dehydrated N,N-dimethylacetamide (DMAc) was added so that the polymer weight was 17% by mass of the total weight. The vial was filled with nitrogen and stirred overnight to dissolve the polymer, preparing a polymer solution. Aluminum foil was placed on the collector of an electrospinning device NANON-04 (manufactured by MECC), and a syringe filled with the polymer solution was set to the electrospinning device. Electrospinning was performed with the polymer solution discharge rate set to 0.1 mL / hour. The distance between the syringe and the collector was set to 12.5 cm, and a voltage of 25 kV was applied to the syringe. This resulted in a Production Example 26-4 / PBI (20 / 80) composite nanofiber nonwoven fabric being laminated on the aluminum foil. The resulting composite nanofibers were vacuum-dried at 60°C for 15 hours. As a post-treatment, the resulting composite nanofibers were immersed in hydrochloric acid (0.1 M) at room temperature for 3 hours and then washed with pure water. The acid-treated composite nanofibers were vacuum-dried at 60°C for 15 hours. This post-treatment allows the triethylamine salt of the polymer compound obtained in Production Example 26-4 to be converted to the proton form. A portion of the nanofibers was osmium-coated and then observed with a scanning electron microscope (SEM, JEOL JSM-6100). The fiber diameter of the produced nanofibers was calculated from the resulting SEM images. The SEM images confirmed that nanofibers with a fiber diameter of 628±131 nm were obtained. The results are shown in Figure 2.

[0054] Example 8: Preparation of PVA-only nanofiber nonwoven fabric / Production Example 26-2 electrolyte membrane An electrolyte membrane was prepared using a PVA-only nanofiber nonwoven fabric and Production Example 26-2 as the matrix polymer. The mass ratio was set to 10 / 100, taking into account porosity and density. A PVA-only nanofiber nonwoven fabric with a thickness of approximately 18 μm, obtained in the same manner as in Example 6, was placed in a glass petri dish, and a 2-methoxyethanol solution (3 wt %) of Production Example 26-2 was cast onto it. The solvent was then slowly evaporated under ambient air at room temperature. The resulting membrane was then vacuum-dried at 60°C for 12 hours to obtain a PVA-only nanofiber nonwoven fabric / Production Example 26-2 electrolyte membrane. The membrane thickness of the electrolyte membrane was approximately 28 μm. Example 9: Preparation of Phy-PBI-only nanofiber nonwoven fabric / Production Example 26-23 electrolyte membrane An electrolyte membrane was prepared using a PBI-only nanofiber nonwoven fabric and the polymer compound obtained in Production Example 26-23 as the matrix polymer. The mass ratio was set to 10 / 100, taking into account porosity and density. PBI nanofiber nonwoven fabric (obtained in the same manner as in Example 1) was modified with an acidic substance. The PBI nanofibers were immersed in a 50 wt% aqueous phytic acid solution at room temperature for 1 hour, then repeatedly washed in pure water at 80°C for a total of 24 hours to remove undoped phytic acid. The phytic acid-modified nanofibers were vacuum-dried at 80°C for 12 hours. This treatment enabled the modification of the basic polymer nanofibers with only phytic acid, which interacts with acid and base. The change in nanofiber weight before and after surface modification revealed that the proportion of molecularly modified sites relative to the entire surface-modified nanofiber was 7.9 wt%. The resulting PBI-only nanofiber nonwoven fabric, approximately 30 μm thick, was placed in a glass Petri dish, and a 1.2 wt% DMSO solution of the polymer compound obtained in Production Examples 26-23 was cast onto it. The solvent was then slowly evaporated at 40°C in air. The resultant was vacuum-dried at 60° C. for 12 hours to obtain a PBI-only nanofiber nonwoven fabric / electrolyte membrane of Production Example 26-23. The thickness of the electrolyte membrane was about 52 μm.

[0055] Example 10: Preparation of PBI-only nanofiber nonwoven fabric / Production Example 26-23 electrolyte membrane An electrolyte membrane was prepared using a PBI-only nanofiber nonwoven fabric (obtained in the same manner as in Example 1) and the polymer compound obtained in Production Example 26-23 as the matrix polymer. The mass ratio was set to 10 / 100, taking into consideration porosity and density. A PBI-only nanofiber nonwoven fabric with a thickness of approximately 30 μm was placed in a glass petri dish, and a DMSO solution (1.2 wt %) of the polymer compound obtained in Production Example 26-23 was cast into it. The solvent was slowly evaporated at 40°C under atmospheric pressure. The membrane was then vacuum-dried at 60°C for 12 hours to obtain a PBI-only nanofiber nonwoven fabric / Production Example 26-23 electrolyte membrane. The membrane thickness of the electrolyte membrane was approximately 61 μm. Example 11: Preparation of PVA-only nanofiber nonwoven fabric / Production Example 26-23 electrolyte membrane An electrolyte membrane was prepared using a PVA-only nanofiber nonwoven fabric and the polymer compound obtained in Production Example 26-23 as a matrix polymer. The mass ratio was set to 10 / 100, taking into consideration porosity and density. A PVA-only nanofiber nonwoven fabric with a thickness of approximately 18 μm, obtained in the same manner as in Example 7, was placed in a glass petri dish, and a DMSO solution (1.2 wt %) of the polymer compound obtained in Production Example 26-23 was cast onto it. The solvent was slowly evaporated under ambient air at room temperature. The membrane was then vacuum-dried at 60°C for 12 hours to obtain a PVA-only nanofiber nonwoven fabric / Production Example 26-23 electrolyte membrane. The membrane thickness of the electrolyte membrane was approximately 49 μm.

[0056] Example 12: Preparation of PBI-only nanofiber nonwoven fabric / s[Is-PTP](PTP-IPC)1_70-30 electrolyte membrane. An electrolyte membrane was prepared using a PBI-only nanofiber nonwoven fabric and s[Is-PTP](PTP-IPC)1_70-30 as the matrix polymer. A PBI-only nanofiber nonwoven fabric with a thickness of approximately 18 μm and a 2-methoxyethanol solution (7.1 wt%) of s[Is-PTP](PTP-IPC)1_70-30 were used to form a membrane using a coater. The solvent was slowly evaporated at room temperature under atmospheric pressure. The membrane was then vacuum-dried at 60°C for 12 hours to obtain a PBI-only nanofiber nonwoven fabric / s[Is-PTP](PTP-IPC)1_70-30 electrolyte membrane. The membrane thickness was approximately 18 μm. Example 13: Preparation of Phy-PBI Pure Nanofiber Nonwoven Fabric / s[Is-PTP](PTP-IPC)1_70-30 Electrolyte Membrane An electrolyte membrane was prepared using a Phy-PBI pure nanofiber nonwoven fabric and s[Is-PTP](PTP-IPC)1_70-30 as the matrix polymer. First, the PBI nanofiber nonwoven fabric was modified with an acidic substance. The PBI nanofiber was immersed in a phytic acid aqueous solution (50 wt%) at room temperature for 1 hour, then repeatedly washed in pure water at 80°C for a total of 24 hours to remove undoped phytic acid. The phytic acid-modified nanofiber was then vacuum-dried at 80°C for 12 hours. This treatment enabled the modification of only the phytic acid, which interacts with the acid and base, on the basic polymer nanofiber. The weight change of the nanofiber before and after surface modification revealed that the proportion of the molecularly modified portion relative to the entire surface-modified nanofiber was so small that it was below the detection limit of an electronic balance. Next, a membrane was formed using the resulting PBI-only nanofiber nonwoven fabric with a thickness of approximately 18 μm and a 2-methoxyethanol solution (7.1 wt%) of s[Is-PTP](PTP-IPC)1_70-30 using a coater. The solvent was slowly evaporated at room temperature under atmospheric pressure. The membrane was then vacuum dried at 60°C for 12 hours to obtain a PBI-only nanofiber nonwoven fabric / s[Is-PTP](PTP-IPC)1_70-30 electrolyte membrane. The membrane thickness was approximately 18 μm.Example 14: Preparation of PVA-only nanofiber nonwoven fabric / s[Is-PTP](PTP-IPC)1_70-30 electrolyte membrane An electrolyte membrane was prepared using a PVA-only nanofiber nonwoven fabric and s[Is-PTP](PTP-IPC)1_70-30 as the matrix polymer. First, polyvinyl alcohol (PVA) was added to a vial, and distilled water was added so that the polymer weight was 10% by mass of the total weight. After stirring at 150 rpm for 5-10 minutes at room temperature, the solution was heated and stirred at 150 rpm for 1 hour at 90°C to dissolve the polymer, preparing a polymer solution. Aluminum foil was placed on the collector of an electrospinning apparatus NANON-04 (manufactured by MECC). A syringe filled with the polymer solution after stirring at room temperature for half a day to a day was attached to the electrospinning apparatus, and electrospinning was performed at a polymer solution release rate of 0.5 mL / hour. The distance between the syringe and the collector was set to 15 cm, and a voltage of 25 kV was applied to the syringe. This resulted in the PVA nanofiber nonwoven fabric being laminated on aluminum foil. A crosslinking agent for the PVA nanofiber nonwoven fabric was prepared by diluting a 50% by mass glutaraldehyde (GA) solution with acetone as a solvent and hydrochloric acid as a catalyst to a 20 mM GA concentration. The PVA nanofiber nonwoven fabric was immersed in this crosslinking agent at room temperature for 1 hour, washed with acetone, and then vacuum-dried overnight at 60°C. Acetalization of one GA molecule with four hydroxyl groups in the PVA in an acidic solution allows PVA molecules to be crosslinked by the GA, thereby insolubilizing the readily soluble PVA. A portion of the nanofibers was osmium-coated and observed with a scanning electron microscope (SEM, JEOL JSM-6100). The fiber diameter of the nanofibers was calculated from the resulting SEM image. SEM images confirmed that uniform nanofibers were produced, and the fiber diameter was 200 nm. The fiber mat was cut into 4 cm squares, and the porosity was calculated from the apparent volume (V) calculated from the dry mass (W) and the film thickness measured with a film thickness meter, and the density of the PVA (1.27 g / cm). ３) was used to calculate the porosity using the following formula: Porosity (%) = (1 - (W / (V x 1.27)) x 100 The calculated porosity was approximately 86%. The resulting PVA-only nanofiber nonwoven fabric with a thickness of approximately 10 μm and a 2-methoxyethanol solution (7.1 wt%) of s[Is-PTP](PTP-IPC)1_70-30 were used to form a membrane using a coater, and the solvent was slowly evaporated at room temperature in the atmosphere. The membrane was then vacuum dried at 60°C for 12 hours to obtain a PBI-only nanofiber nonwoven fabric / s[Is-PTP](PTP-IPC)1_70-30 electrolyte membrane. The membrane thickness was approximately 23 μm.

[0057] Example 15: Preparation of PBI-only nanofiber nonwoven fabric / s[Is / PrP30-PTP](PTP-IPC)1_70-30 electrolyte membrane. An electrolyte membrane was prepared using a PBI-only nanofiber nonwoven fabric and s[Is / PrP30-PTP](PTP-IPC)1_70-30 as the matrix polymer. A PBI-only nanofiber nonwoven fabric with a thickness of approximately 18 μm and a 2-methoxyethanol solution (4.4 wt%) of s[Is / PrP30-PTP](PTP-IPC)1_70-30 were used to form a membrane using a coater. The solvent was slowly evaporated at room temperature under atmospheric pressure. The membrane was then vacuum-dried at 60°C for 12 hours to obtain a PBI-only nanofiber nonwoven fabric / s[Is / PrP30-PTP](PTP-IPC)1_70-30 electrolyte membrane. The electrolyte membrane had a thickness of approximately 17 μm. Example 16: Fabrication of Phy-PBI Monolayer Nanofiber Nonwoven Fabric / s[Is / PrP30-PTP](PTP-IPC)1_70-30 Electrolyte Membrane An electrolyte membrane was fabricated using a Phy-PBI monolayer nanofiber nonwoven fabric and s[Is / PrP30-PTP](PTP-IPC)1_70-30 as the matrix polymer. First, the PBI nanofiber nonwoven fabric was modified with an acidic substance. The PBI nanofiber was immersed in a phytic acid aqueous solution (50 wt%) at room temperature for 1 hour, then repeatedly washed in pure water at 80°C for a total of 24 hours to remove undoped phytic acid. The phytic acid-modified nanofiber was then vacuum-dried at 80°C for 12 hours. This treatment enabled the modification of only the phytic acid, which interacts with the acid and base, on the basic polymer nanofiber. The change in nanofiber weight before and after surface modification indicated that the proportion of molecularly modified sites relative to the total surface-modified nanofiber was so small that it was below the detection limit of the electronic balance. Next, a membrane was formed using the resulting PBI-only nanofiber nonwoven fabric with a thickness of approximately 18 μm and a 2-methoxyethanol solution (4.4 wt%) of s[Is / PrP30-PTP](PTP-IPC)1_70-30 using a coater. The solvent was slowly evaporated at room temperature under atmospheric pressure. The membrane was then vacuum-dried at 60°C for 12 hours to obtain a PBI-only nanofiber nonwoven fabric / s[Is / PrP30-PTP](PTP-IPC)1_70-30 electrolyte membrane. The membrane thickness was approximately 17 μm.Example 17: Preparation of PVA-only nanofiber nonwoven fabric / s[Is / PrP30-PTP](PTP-IPC)1_70-30 electrolyte membrane An electrolyte membrane was prepared using a PVA-only nanofiber nonwoven fabric and s[Is / PrP30-PTP](PTP-IPC)1_70-30 as the matrix polymer. First, polyvinyl alcohol (PVA) was added to a vial, followed by distilled water so that the polymer weight was 10% by mass of the total weight. After stirring at 150 rpm for 5-10 minutes at room temperature, the mixture was heated and stirred at 150 rpm for 1 hour at 90°C to dissolve the polymer, preparing a polymer solution. Aluminum foil was placed on the collector of an electrospinning apparatus NANON-04 (manufactured by MECC). A syringe filled with the polymer solution after stirring for half a day to a day at room temperature was set in the electrospinning apparatus, and electrospinning was performed with a polymer solution discharge rate of 0.5 mL / hour. The distance between the syringe and the collector was set to 15 cm, and a voltage of 25 kV was applied to the syringe. This resulted in a PVA nanofiber nonwoven fabric being laminated on the aluminum foil. A crosslinking agent for the PVA nanofiber nonwoven fabric was prepared by diluting a 50% by weight glutaraldehyde (GA) solution with acetone as a solvent and hydrochloric acid as a catalyst to a concentration of 20 mM. The PVA nanofiber nonwoven fabric was immersed in this crosslinking agent at room temperature for 1 hour, washed with acetone, and then vacuum-dried overnight at 60°C. In an acidic solution, acetalization of one GA molecule with four hydroxyl groups in PVA results in crosslinking of PVA molecules by GA, making it possible to insolubilize the readily soluble PVA. A portion of the nanofiber was used and osmium-coated, then observed with a scanning electron microscope (SEM, JEOL JSM-6100), and the fiber diameter of the nanofibers produced was calculated from the resulting SEM image. The SEM images confirmed that uniform nanofibers had been produced, and the fiber diameter was 200 nm. The porosity was calculated by cutting a 4 cm square fiber mat and calculating the apparent volume (V) from the dry mass (W) and the film thickness measured with a film thickness meter, and the density of the PVA (1.27 g / cm). ３) was used to calculate the porosity using the following formula: Porosity (%) = (1 - (W / (V × 1.27)) × 100 The calculated porosity was approximately 86%. The resulting PVA-only nanofiber nonwoven fabric with a thickness of approximately 10 μm and a 2-methoxyethanol solution (4.4 wt%) of s[Is / PrP30-PTP](PTP-IPC)1_70-30 were used to form a membrane using a coater, and the solvent was slowly evaporated at room temperature in the atmosphere. The membrane was then vacuum-dried at 60°C for 12 hours to obtain a PBI-only nanofiber nonwoven fabric / s[Is / PrP30-PTP](PTP-IPC)1_70-30 electrolyte membrane. The membrane thickness was approximately 18 μm.

[0058] [Proton Conductivity Measurement of Various Electrolyte Membranes] Using an Impedance Analyzer 3532-50 (manufactured by Hioki Corporation), the frequency response from 50 kHz to 5 MHz was measured, and the resistance of the electrolyte membrane (electrode distance 1.0 cm) was measured. The temperature and humidity during resistance measurement were maintained at 80°C, 70% RH, and 80°C, 90% RH, respectively, using a thermo-hygrostat SH-221 (manufactured by ESPEC Corporation). Using the resistance [Ω], electrode distance [cm], and membrane cross-sectional area [cm2] obtained by impedance measurement, the proton conductivity [mS / cm] was calculated from the formula electrode distance [cm] / (membrane cross-sectional area [cm2] × resistance [Ω]). The results are shown in Tables 6 to 8. For comparison, the proton conductivity was also measured for a Recast-Nafion (registered trademark) membrane (Comparative Example 1) and a Nafion NR-211 (trade name) membrane (Comparative Example 2). The results are shown in each table.

[0059]

[0060]

[0061]

Claims

1. A matrix material used in a composite membrane containing nanofibers and a matrix material, characterized in that the matrix material contains a polymer compound containing sulfonic acid groups and / or phosphonic acid groups.

2. The matrix material according to claim 1, wherein the polymer compound is a compound that does not contain fluorine.

3. The matrix material according to claim 1, wherein the polymer compound has a low-reducing group in the main chain skeleton.

4. The matrix material according to claim 3, wherein said low-reducing group is a ketone group or a substituent having a C=O structure.

5. The matrix material according to claim 1, wherein said polymer compound further has a nitrogen-containing compound group.

6. The matrix material according to claim 1, wherein the polymer compound has a low-reducing group and a sulfonic acid group and / or a phosphonic acid group in the main chain skeleton.

7. A nanofiber used in an electrolyte membrane containing nanofibers and the matrix material of claim 1, characterized in that the nanofiber is formed using a polymer compound for nanofibers containing sulfonic acid groups and / or phosphonic acid groups.

8. An electrolyte membrane comprising a matrix material containing a polymer compound containing sulfonic acid groups and / or phosphonic acid groups.

9. An electrolyte membrane comprising the nanofibers of claim 7 and the matrix material of claim 1.

10. A fuel cell comprising the electrolyte membrane according to claim 8 or 9.

11. A water electrolyzer using the electrolyte membrane according to claim 9.

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