Composite electrolyte membrane

Abstract

The present application relates to a composite electrolyte membrane. The object of the present invention is to provide a composite electrolyte membrane which is excellent in chemical resistance and can maintain sufficient mechanical strength even under high humidity and high pressure conditions as operating conditions of an electrochemical hydrogen pump and a water electrolysis device. The composite electrolyte membrane of the present invention for achieving the above object has a composite layer in which a mesh fabric and a polymer electrolyte are compounded, the mesh fabric containing liquid crystal polyester fibers or polyphenylene sulfide fibers and satisfying (1) and (2) below, (1) yarn thickness (μm) / fiber diameter (μm) < 2.0, (2) opening (μm) / fiber diameter (μm) > 1.0.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 201980020302.6 (PCT Application No. PCT / JP2019 / 012456) filed on March 25, 2019, entitled “Composite Electrolyte Membrane”. TECHNICAL FIELD

[0002] The present application relates to a composite electrolyte membrane. BACKGROUND

[0003] In recent years, hydrogen energy is attracting attention as a next-generation energy storage and transport means. With respect to hydrogen, by being used as a fuel for a fuel cell, it is possible to convert electric power with higher energy efficiency than power generation using a heat engine in theory, and there is no harmful exhaust, so it can become a highly efficient clean energy source.

[0004] Hydrogen is a secondary energy, and there are various production methods. If surplus electric power generated by renewable energy is used to electrolyze water, it is possible to convert electric power into hydrogen energy without emitting carbon dioxide. The hydrogen production method based on water electrolysis includes alkaline water electrolysis and solid polymer electrolyte membrane (PEM) type water electrolysis. The PEM type water electrolysis has the following advantages: it can operate at high current density, and it can flexibly respond to output fluctuations of renewable energy.

[0005] In addition, hydrogen can be transported using tank trucks or tankers depending on the storage method, so it can be supplied to areas where demand is high when needed, and in this respect, it has a great advantage over electric power storage. Hydrogen storage methods include compressed hydrogen, liquid hydrogen, and hydrogen occlusion into alloys. Among these, compressed hydrogen is in increasing demand from the viewpoint of being able to be used immediately as a gaseous fuel and from the viewpoint of energy efficiency.

[0006] As a method of producing compressed hydrogen, a positive displacement compressor has been used in the past, but in recent years, an electrochemical hydrogen pump has attracted attention. The electrochemical hydrogen pump is a hydrogen compressor that compresses hydrogen electrochemically by circulating electric current in a solid polymer electrolyte membrane with a catalyst layer. Compared to a positive displacement compressor, it has the following advantages: higher energy efficiency and quietness, and it is compact, and in addition, it can also perform hydrogen purification.

[0007] As an electrolyte membrane used in such an electrochemical hydrogen pump or water electrolysis device, a case using “Nafion (registered trademark)” manufactured by the U.S. company Dupont, which is a representative fluorine-based polymer electrolyte membrane, is reported in Non-Patent Literature 1. In addition, a case using a hydrocarbon-based electrolyte membrane is reported in Patent Literature 1. In Patent Literature 2, an electrolyte membrane in which a fiber fabric composed of polyethylene fibers or polyether ether ketone fibers is used as a reinforcing material is reported.

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2016-216826

[0011] Patent Document 2: Japanese Patent Application Publication No. 2005-108662

[0012] Non-Patent Documents

[0013] Non-Patent Document 1: International Journal of Hydrogen Energy, 38 (2013) 4901-4934 SUMMARY

[0014] PROBLEMS TO BE SOLVED BY THE INVENTION

[0015] However, the fluorine-based electrolyte membrane and the hydrocarbon-based electrolyte membrane used in Non-Patent Document 1 and Patent Document 1, which do not have a reinforcing material, are accompanied by a large decrease in mechanical strength with an increase in water content. Therefore, the mechanical strength is not sufficient as an electrolyte membrane for an electrochemical hydrogen pump that operates under high humidity and high pressure conditions, or a water electrolysis device that operates under hot water conditions.

[0016] Therefore, as an electrolyte membrane used in an electrochemical hydrogen pump or a water electrolysis device, a composite electrolyte membrane using a fiber cloth as a reinforcing material used in Patent Document 2 becomes a candidate. However, the conventional composite electrolyte membrane cannot maintain sufficient mechanical strength under high humidity and high pressure conditions when used in an electrochemical hydrogen pump or a water electrolysis device.

[0017] An object of the present application is to provide a composite electrolyte membrane that is excellent in chemical resistance and can maintain sufficient mechanical strength even under high humidity and high pressure conditions as operating conditions of an electrochemical hydrogen pump or a water electrolysis device.

[0018] MEANS FOR SOLVING THE PROBLEMS

[0019] The foregoing object of the present application can be achieved by the following means.

[0020] <1> A composite electrolyte membrane having a composite layer in which a mesh fabric and a polymer electrolyte are compounded,

[0021] The mesh fabric contains liquid crystal polyester fibers or polyphenylene sulfide fibers, and satisfies the following (1) and (2),

[0022] (1) Yarn thickness (pm) / fiber diameter (pm) < 2.0

[0023] (2) Opening (pm) / fiber diameter (pm) > 1.0.

[0024] <2> The composite electrolyte membrane according to <1>, wherein the mesh fabric comprises liquid crystalline polyester fibers comprising a liquid crystalline polyester single component.

[0025] <3> The composite electrolyte membrane according to <1> or <2>, wherein the liquid crystalline polyester fibers comprise a wholly aromatic polyester.

[0026] <4> The composite electrolyte membrane according to <3>, wherein the wholly aromatic polyester is a liquid crystalline polyester comprising the following structural units (I), (II), (III), (IV), and (V),

[0027] [Chemical Formula 1]

[0028]

[0029] <5> The composite electrolyte membrane according to any one of <1> to <4>, wherein the fiber diameter of the fibers constituting the mesh fabric is 50 μm or less.

[0030] <6> The composite electrolyte membrane according to any one of <1> to <5>, wherein the opening of the mesh fabric is 30 μm or more.

[0031] <7> The composite electrolyte membrane according to any one of <1> to <6>, wherein the open area of the mesh fabric is 30% or more.

[0032] <8> The composite electrolyte membrane according to any one of <1> to <7>, wherein the permeation volume of the mesh fabric is 10 cc / m 2 or more.

[0033] <9> The composite electrolyte membrane according to any one of <1> to <8>, wherein the yarn thickness of the mesh fabric is 50 μm or less.

[0034] <10> The composite electrolyte membrane according to any one of <1> to <9>, wherein the heat of fusion ΔHml of the mesh fabric is 6.0 J / g or less.

[0035] <11> The composite electrolyte membrane according to any one of <1> to <10>, wherein the polymer electrolyte is a hydrocarbon-based polymer electrolyte.

[0036] <12> An electrolyte membrane with a catalyst layer, which has a catalyst layer on both sides of the composite electrolyte membrane according to any one of <1> to <11>.

[0037] <13> A membrane electrode composite comprising the composite electrolyte membrane according to any one of <1> to <11>.

[0038] <14> An electrochemical hydrogen pump using the composite electrolyte membrane according to any one of <1> to <11>.

[0039] <15> A water electrolysis device using the composite electrolyte membrane according to any one of <1> to <11>.

[0040] Effects of the Invention

[0041] The composite electrolyte membrane of the present application is excellent in chemical resistance, and can maintain sufficient mechanical strength even under high humidity and high pressure conditions which are operating conditions of an electrochemical hydrogen pump and a water electrolysis device. DETAILED DESCRIPTION

[0042] The composite electrolyte membrane of the present application has a composite layer in which a mesh fabric containing liquid crystalline polyester fibers or polyphenylene sulfide fibers is combined with a polymer electrolyte, and satisfies the following (1) and (2).

[0043] (1) Yarn thickness (pm) / fiber diameter (pm) < 2.0

[0044] (2) Opening (pm) / fiber diameter (pm) > 1.0.

[0045] Hereinafter, the composite electrolyte membrane of the present application will be described in detail.

[0046] [Polymer electrolyte]

[0047] In the present application, the polymer electrolyte can be a fluorine-based polymer electrolyte or a hydrocarbon-based polymer electrolyte.

[0048] The so-called fluorine-based polymer electrolyte refers to a polymer having a main chain with perfluorocarbon as a main structural unit, and an ionic group imparted to the main chain or a side chain. As the fluorine-based polymer electrolyte, specifically, perfluorocarbon sulfonic acid-based polymers such as Nafion (registered trademark, manufactured by Dupont), Aciplex (registered trademark, manufactured by Asahi Kasei Corporation), Flemion (registered trademark, manufactured by Asahi Glass Company, Ltd.), polytrifluorostyrene sulfonic acid-based polymers, perfluorocarbon phosphonic acid-based polymers, trifluorostyrene sulfonic acid-based polymers, ethylene tetrafluoroethylene-g-styrene sulfonic acid-based polymers, ethylene-tetrafluoroethylene copolymers, polyvinylidene fluoride-perfluorocarbon sulfonic acid-based polymers, ethylene-tetrafluoroethylene copolymers, resins in which trifluorostyrene is used as a raw polymer, and the like can be listed. From the viewpoint of chemical stability and power generation performance, a fluorine-based polymer electrolyte composed of a perfluorocarbon sulfonic acid-based polymer is particularly preferable.

[0049] The so-called hydrocarbon-based polymer electrolyte refers to a hydrocarbon-based polymer having an ionic group. The so-called hydrocarbon-based polymer refers to a polymer having a main chain in which a hydrocarbon is the main structural unit, and an ionic group is imparted to the main chain or side chain, in which the main chain or side chain is not substantially fluorinated. Note that the so-called substantially not fluorinated refers to a polymer in which a portion fluorinated is not excluded from a very small part of the main chain or side chain, and specifically, a polymer in which the content of fluorine atoms is less than 5% based on the number average molecular weight of the polymer is also included, and is referred to as a hydrocarbon-based polymer.

[0050] In the composite electrolyte membrane of the present application, it is more preferable that the aforementioned polymer electrolyte is a hydrocarbon-based polymer electrolyte, for the reason that the hydrocarbon-based polymer electrolyte has high mechanical strength, high gas barrier property, high proton conductivity as an electrolyte, and has good compatibility with the mesh fabric containing liquid crystalline polyester fibers or polyphenylene sulfide fibers used in the present application. If the composite electrolyte membrane using the hydrocarbon-based polymer electrolyte is applied to an electrochemical hydrogen pump or a water electrolysis device, high performance and durability are exhibited. In addition, since the mesh fabric containing liquid crystalline polyester fibers or polyphenylene sulfide fibers has good compatibility with the polymer electrolyte, a uniform composite electrolyte membrane can be easily formed at the time of compounding. Here, the aforementioned compounding refers to a state in which the polymer electrolyte is filled in the voids contained in the mesh fabric, and the aforementioned composite layer refers to a polymer electrolyte membrane layer having a structure in which the polymer electrolyte is filled in the voids of the mesh fabric.

[0051] As the hydrocarbon-based polymer constituting the hydrocarbon-based polymer electrolyte, an aromatic hydrocarbon-based polymer is particularly preferable. The so-called aromatic hydrocarbon-based polymer refers to a polymer containing a hydrocarbon skeleton having an aromatic ring in the main chain, and as specific examples, a polymer having a structure selected from the group consisting of an aromatic ring and a structure of poly sulfone, poly ether sulfone, polyphenylene ether, poly aryl ether-based polymer, polyphenylene sulfide, polyphenylene sulfide sulfone, poly p-phenylene, poly arylene-based polymer, poly arylene ketone, poly ether ketone, poly arylene phosphine oxide, poly ether phosphine oxide, polybenzoxazole, polybenzothiazole, polybenzimidazole, polyamide, polyimide, polyetherimide, polyimide sulfone in the main chain can be listed. Note that the poly sulfone, poly ether sulfone, poly ether ketone, etc. mentioned here are a collective term for structures having a sulfone bond, ether bond, ketone bond in the molecular chain, and include poly ether ketone ketone, poly ether ether ketone, poly ether ether ketone ketone, poly ether ketone ether ketone ketone, poly ether ketone sulfone, etc. The hydrocarbon skeleton can have multiple structures among these structures. Among them, a polymer having a poly ether ketone structure in the main chain is most preferable.

[0052] The ionic group of the high molecular electrolyte is an ionic group having a proton exchange ability. As such an ionic group, a sulfonic acid group, a sulfonimide group, a sulfuric acid group, a phosphonic acid group, a phosphoric acid group, a carboxylic acid group are preferably used. Two or more kinds of ionic groups can be contained in the polymer. Among them, from the aspect of high proton conductivity, the polymer is more preferably at least having a sulfonic acid group, a sulfonimide group, a sulfuric acid group, and from the aspect of raw material cost, most preferably having a sulfonic acid group.

[0053] Mesh fabric

[0054] The mesh fabric used as the reinforcing material in the present application contains liquid crystalline polyester fibers or polyphenylene sulfide fibers. By using the mesh fabric containing liquid crystalline polyester fibers or polyphenylene sulfide fibers, a composite electrolyte membrane excellent in chemical resistance and mechanical strength can be obtained. Among them, in the aspect of easily obtaining a composite electrolyte membrane having more excellent mechanical strength, the aforementioned mesh fabric preferably contains liquid crystalline polyester fibers.

[0055] In the present specification, the liquid crystalline polyester fiber means a fiber in which 50% or more of the area ratio of the fiber cross section is liquid crystalline polyester. By having 50% or more of the fiber cross section be liquid crystalline polyester, the mechanical properties and chemical resistance possessed by liquid crystalline polyester are exhibited as a whole of the fiber.

[0056] As for the liquid crystalline polyester fiber used in the present application, if 50% or more of the fiber cross section is liquid crystalline polyester, it can be a composite fiber with other components, but in order to strongly exhibit the properties of liquid crystalline polyester, the higher the ratio of liquid crystalline polyester in the fiber cross section is more preferable. Specifically, it is preferable that 60% or more of the fiber cross section be liquid crystalline polyester, more preferably 70% or more be liquid crystalline polyester, and further preferably be formed of a single component of liquid crystalline polyester. By the liquid crystalline polyester fiber being formed of a single component of liquid crystalline polyester, high chemical resistance can be easily exhibited.

[0057] Note that, in the case of being made into a composite fiber with other components, it can be achieved by being made into a core-sheath composite fiber or an island-in-the-sea composite fiber. As a specific product name of such a fiber, "VECRY" (registered trademark) manufactured by Kuraray Co., Ltd. can be cited.

[0058] The liquid crystalline polyester means a polyester that can form an anisotropic melt phase (liquid crystallinity) at the time of melting. This property can be confirmed, for example, by placing a sample formed of the liquid crystalline polyester on a hot stage, performing temperature elevation heating under a nitrogen atmosphere, and observing the transmitted light of the sample under polarized light.

[0059] In the present application, as the liquid crystalline polyester used in the liquid crystalline polyester fiber constituting the mesh fabric, for example, the following can be cited:

[0060] a. a polymer of an aromatic hydroxy carboxylic acid;

[0061] b. a polymer of an aromatic dicarboxylic acid with an aromatic diol or an aliphatic diol;

[0062] c. a copolymer of a and b; and the like.

[0063] Among them, in order to have high strength, high elastic modulus, and high heat resistance, the aforementioned liquid crystalline polyester fiber preferably contains a wholly aromatic polyester. Note that, in the present specification, the term "wholly aromatic polyester" means a polyester that does not use any of aliphatic diols or aliphatic dicarboxylic acids.

[0064] Here, as the aromatic hydroxycarboxylic acid, hydroxybenzoic acid, hydroxynaphthoic acid, or the like, or an alkyl-, alkoxy-, or halogen-substituted compound of the aforementioned aromatic hydroxycarboxylic acid can be exemplified.

[0065] As the aromatic dicarboxylic acid, terephthalic acid, isophthalic acid, diphenyl dicarboxylic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyloxyethane dicarboxylic acid, diphenylethane dicarboxylic acid, or the like, or an alkyl-, alkoxy-, or halogen-substituted compound of the aforementioned aromatic dicarboxylic acid can be exemplified.

[0066] As the aromatic diol, hydroquinone, resorcinol, dioxin, naphthalene glycol, or the like, or an alkyl-, alkoxy-, or halogen-substituted compound of the aforementioned aromatic diol can be exemplified.

[0067] As the aliphatic diol, ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, or the like can be exemplified.

[0068] As the liquid crystalline polyester used in the present application, a liquid crystalline polyester obtained by copolymerizing a p-hydroxybenzoic acid component, a 4,4'-dihydroxydiphenyl component, a hydroquinone component, and a terephthalic acid component and / or an isophthalic acid component; a liquid crystalline polyester obtained by copolymerizing a p-hydroxybenzoic acid component and a 6-hydroxy-2-naphthoic acid component; a liquid crystalline polyester obtained by copolymerizing a p-hydroxybenzoic acid component, a 6-hydroxy-2-naphthoic acid component, a hydroquinone component, and a terephthalic acid component; and the like, which are excellent in high strength, high elastic modulus, and drug resistance, can be exemplified as preferable examples.

[0069] In the present application, it is particularly preferable that the aforementioned wholly aromatic polyester be a liquid crystalline polyester containing the following structural units (I), (II), (III), (IV), and (V). Note that, in the present application, the term "structural unit" means a unit that can constitute a repeating structure in the main chain of a polymer.

[0070] [Chemical Formula 1]

[0071]

[0072] The molecular chain has proper crystallinity and non-linearity by the combination, and thus the fiber strength and elastic modulus can be improved, so that even if the fiber diameter is small, high mechanical properties can be easily obtained. In addition, the wear resistance can be improved, so that it is suitable for mesh fabrics with large volume. Furthermore, the fiber collapses easily in the transverse direction (perpendicular to the fiber axis), so that the yarn thickness can be easily reduced.

[0073] Furthermore, the liquid crystalline polyester containing the aforementioned structural units (I), (II), (III), (IV), and (V) can obtain a structure in which the molecular chain in the fiber is ordered and less disordered by containing the component containing the diol with small volume and high linearity such as structural units (II) and (III), and can easily maintain the interaction in the perpendicular direction to the fiber axis even if the crystallinity is not excessively increased. Thus, in addition to high strength and elastic modulus, particularly excellent wear resistance can be easily obtained by performing high-temperature heat treatment after solid-phase polymerization.

[0074] In addition, the aforementioned structural unit (I) is preferably 40 to 85 mol%, more preferably 65 to 80 mol%, and further preferably 68 to 75 mol% with respect to the total of structural units (I), (II), and (III). By being in such a range, the crystallinity can be brought to an appropriate range, and high strength and elastic modulus can be easily obtained.

[0075] The structural unit (II) is preferably 60 to 90 mol%, more preferably 60 to 80 mol%, and further preferably 65 to 75 mol% with respect to the total of structural units (II) and (III). By being in such a range, the interaction in the perpendicular direction to the fiber axis can be maintained even if the crystallinity is not excessively increased, and thus the wear resistance can be improved, so that it is suitable for mesh fabrics with large volume, and furthermore, the fiber collapses easily in the transverse direction (perpendicular to the fiber axis), so that the yarn thickness can be reduced.

[0076] The structural unit (IV) is preferably 40 to 95 mol%, more preferably 50 to 90 mol%, and further preferably 60 to 85 mol% with respect to the total of structural units (IV) and (V). By being in such a range, the linearity of the polymer is moderately disturbed, and thus the wear resistance can be improved, so that it is suitable for mesh fabrics with large volume, and furthermore, the fiber collapses easily in the transverse direction (perpendicular to the fiber axis), so that the yarn thickness can be reduced.

[0077] The preferable ranges of each structural unit of the liquid crystalline polyester used in the present application are described below. By adjusting the composition so that the above conditions are satisfied in the ranges, the liquid crystalline polyester fiber used in the present application can be well obtained.

[0078] Structural unit (I) 45 to 65 mol%

[0079] Structural unit (II) 12 to 18 mol%

[0080] Structural unit (III) 3 to 10 mol%

[0081] Structural unit (IV) 5 to 20 mol%

[0082] Structural unit (V) 2 to 15 mol%

[0083] Note that, in addition to the above structural units, aromatic dicarboxylic acids such as 3,3'-diphenyl dicarboxylic acid and 2,2'-diphenyl dicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid, alicyclic dicarboxylic acids such as hexahydro-p-xylylene dicarboxylic acid (1,4-cyclohexane dicarboxylic acid), chlorohydroquinone, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxybenzophenone, and aromatic diols such as p-aminophenol can be copolymerized with the liquid crystalline polyester used in the present application, in a range of about 5 mol% or less, without impairing the effects of the present application.

[0084] In addition, polymers such as polyester, polyolefin, polystyrene, polycarbonate, polyamide, polyimide, polyphenylene sulfide, polyphenylene ether, polysulfone, aromatic polyketone, aliphatic polyketone, semi-aromatic polyester amide, polyether ether ketone, fluororesin, and the like can be added in a range of about 5 wt% or less, without impairing the effects of the present application, and polyphenylene sulfide, polyether ether ketone, nylon 6, nylon 66, nylon 46, nylon 6T, nylon 9T, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycyclohexane dimethanol terephthalate, polyester 99M, and the like can be cited as preferred examples.

[0085] The polyphenylene sulfide used in the polyphenylene sulfide fiber constituting the mesh fabric in the present application is a polymer in which a p-phenylene sulfide unit, a m-phenylene sulfide unit, and the like represented by the following structural formula (1) are used as the main repeating unit. From the viewpoint of heat resistance, the polyphenylene sulfide used in the present application is preferably a polymer containing 70 mol% or more of the repeating unit represented by the following structural formula (1), and further preferably a polymer containing 90 mol% or more of the repeating unit represented by the following structural formula (1).

[0086] [Chemical Formula 2]

[0087]

[0088] The polyphenylene sulfide used in the present application has a melting point (Tml) of preferably 300°C or lower, more preferably 290°C or lower. By having such a melting point, the fiber production can be performed without making the temperature excessively high in melt spinning, particularly heat stretching, and thus the uniformity of the temperature can be improved, the stability of the fiber production is improved, and thus a fiber having a small fiber diameter can be obtained. The lower limit of the melting point is about 240°C. Note that the melting point referred to in the present application is a value obtained by the method described in item (6) of the Examples.

[0089] The liquid crystalline polyester or the polyphenylene sulfide used in the present application can contain a small amount of various metal oxides, inorganic substances such as kaolin and silica, colorants, matting agents, flame retardants, antioxidants, ultraviolet absorbers, infrared absorbers, crystallization nucleating agents, optical brighteners, end-capping agents, compatibilizers, and the like, within a range not impairing the effects of the present application.

[0090] In the present application, a mesh fabric comprising liquid crystalline polyester fibers or polyphenylene sulfide fibers is used as a reinforcing material. The mesh fabric refers to a fabric formed of warp yarns and weft yarns. As the fabric weave, there are plain weave, twill weave, and the like, and from the viewpoint of being able to reduce the thickness (yarn thickness) of the mesh, plain weave is preferred. In addition, the liquid crystalline polyester fibers or polyphenylene sulfide fibers used in the warp yarns and weft yarns are preferably single filaments. By being single filaments, the width of the fibers can be reduced as compared to multiple filaments, and thus the fiber diameter can be substantially reduced, and further the mesh holes (openings) of the mesh fabric can be made uniform.

[0091] In the present application, the fiber diameter of the fibers constituting the mesh fabric is preferably 50 μm or less. By setting the fiber diameter of the fibers constituting the mesh fabric to 50 μm or less, the volume occupied by the fibers in the entire mesh fabric can be reduced, and when used as a reinforcing material for an electrolyte membrane, the mechanical strength can be improved while maintaining the proton conduction. From this viewpoint, the smaller the fiber diameter, the more preferred it is, and more preferably 40 μm or less, and further preferably 30 μm or less. The lower limit of the fiber diameter is about 10 μm. Note that the fiber diameter in the specification is a value obtained by the method described in item (4) of the Examples.

[0092] In the present application, the opening of the mesh fabric is preferably 30 μm or more. The opening indicates the distance between the fibers of the mesh fabric, that is, the length of the side of the opening. The opening can be calculated from the number of fibers per 1 inch (2.54 cm) width of the mesh fabric, that is, the mesh count, and the fiber diameter, using the following equation.

[0093] Opening (μm) = (25400 / mesh count) - fiber diameter (μm)

[0094] By setting the aperture to 30 μm or more, the opening of the mesh fabric can be enlarged, thereby improving mechanical strength while maintaining proton conduction when used as a reinforcing material for electrolyte membranes. From this viewpoint, a larger aperture is preferred, more preferably 40 μm or more, and even more preferably 50 μm or more. The upper limit of the aperture is about 200 μm. It should be noted that the aperture mentioned in this invention is a value obtained by the method described in Example (4).

[0095] In this invention, the open area (OPA) of the mesh fabric is preferably 30% or more. OPA is an indicator representing the area ratio of the open portions of the mesh, and is calculated using the following formula: OPA (%) = {Openings (μm)} 2 / (pore size (μm) + fiber diameter (μm)) 2}×100

[0096] By setting the OPA to 30% or more, the area ratio of the openings in the mesh fabric can be increased, thereby improving mechanical strength while maintaining proton conduction when used as a reinforcing material for electrolyte membranes. From this perspective, a higher OPA is preferred, and more preferably 40% or more. The upper limit for OPA is approximately 90%. It should be noted that the OPA mentioned in this invention is a value obtained by the method described in Example (4).

[0097] In this invention, the preferred permeability volume of the mesh fabric is 10 cc / m². 2 That's all. Transmittance volume is expressed in meters. 2 An indicator of the volume of openings (permeable portions) in a mesh fabric, expressed in cc / m². 2 The volume is expressed in units. The volume can be calculated using the following formula.

[0098] Through volume (cc / m 2 = (OPA (%) / 100) × yarn thickness (μm)

[0099] By setting the permeable volume to 10cc / m 2 The above allows for a larger opening volume in the mesh fabric, making it easier to improve mechanical strength while maintaining proton conduction when used as a reinforcing material for electrolyte membranes. From this perspective, a larger permeability volume is preferred, and 15cc / m is more preferable. 2 The above. The upper limit for permeable volume is 40cc / m³. 2 Left and right. It should be noted that the permeable volume mentioned in this invention is a value obtained by the method described in item (4) of the embodiment.

[0100] In the present application, the yarn thickness of the mesh fabric is preferably 50 μm or less. By setting the yarn thickness to 50 μm or less, the thickness of the electrolyte membrane as a whole can be made small, and when the electrolyte membrane is used as an electrochemical hydrogen pump or a water electrolysis device, the membrane resistance becomes small, and thus the performance is improved. From this viewpoint, the smaller the yarn thickness, the more preferable, and more preferably, it is below 50 μm, and further preferably, it is 45 μm or less, and most preferably, it is 40 μm or less. As a lower limit of the yarn thickness, it is about 15 μm. Note that the yarn thickness referred to in the present application is a value obtained by the method described in the (5) of the Examples.

[0101] The relationship between the yarn thickness and the fiber diameter of the mesh fabric containing the liquid crystalline polyester fiber or the polyphenylene sulfide fiber used in the present application satisfies the following formula.

[0102] Yarn thickness (μm) / fiber diameter (μm) < 2.0

[0103] The yarn thickness is the height of the intersection of the fibers to each other at the thickest part of the fabric, and for example, in the case of a mesh fabric composed of stainless steel, the yarn thickness is usually 2 or more times the fiber diameter. The fact that the yarn thickness / fiber diameter of the mesh fabric used in the present application is below 2.0 indicates that the fibers collapse in the lateral direction (perpendicular to the fiber axis) at the fiber intersection part of the fabric. By using such a mesh fabric, the yarn thickness can be made small relative to the fiber diameter, the yarn thickness can be made small without lowering the mechanical properties of the mesh required as a reinforcing material, and high reinforcing performance and excellent membrane properties can be combined. From this viewpoint, the smaller the yarn thickness / fiber diameter, the more preferable, and more preferably, it is 1.7 or less, and further preferably, it is 1.4 or less.

[0104] In addition, the relationship between the opening and the fiber diameter of the mesh fabric containing the liquid crystalline polyester fiber or the polyphenylene sulfide fiber used in the present application satisfies the following formula.

[0105] Opening (μm) / fiber diameter (μm) > 1.0

[0106] The fact that the opening / fiber diameter exceeds 1.0 indicates that the interval of the fibers to each other in the mesh fabric is the fiber diameter or more, and it is a state in which the opening part is large. In the case where such a mesh fabric is used as a reinforcing material, the mechanical strength can be improved while maintaining the proton conduction, but the number of fibers decreases, and thus the mechanical properties required as a reinforcing material are lowered. In the present application, particularly in the case of using a liquid crystalline polyester fiber whose strength is extremely high, even in the case where the number of fibers is small, the mechanical properties of the mesh can be maintained in a high state, and thus even in the case where the opening / fiber diameter exceeds 1.0, high reinforcing performance and excellent membrane properties can be combined. From this viewpoint, the larger the opening / fiber diameter, the more preferable, and more preferably, it is 1.5 or more, and further preferably, it is 2.0 or more.

[0107] The mesh fabric comprising the liquid crystalline polyester fiber used in the present application preferably has a half-peak width of 15°C or more for the endothermic peak (Tml) observed in a differential calorimetry measurement under a temperature rising condition of 20°C / minute from 50°C. Tml in this measurement indicates the melting point of the fiber, and in terms of the peak shape, the wider the area, that is, the larger the heat of fusion ΔHml, the higher the degree of crystallinity, and in addition, the narrower the half-peak width, the higher the perfection of the crystallization can be said. Therefore, the point that the half-peak width is as high as 15°C or more indicates that the crystallinity is low, the fibril structure is disordered, and the fiber as a whole is softened, and even in the liquid crystalline polyester fiber, the fiber is easily collapsed in the transverse direction (fiber axis perpendicular direction). The higher the half-peak width of Tml, the more easily the fiber is collapsed in the transverse direction (fiber axis perpendicular direction), and therefore, it is more preferable to be 20°C or less. The upper limit of the half-peak width is around 80°C. Note that the half-peak width referred to in the present application is set to the value obtained by the method described in item (6) of the Examples. In the mesh fabric comprising the liquid crystalline polyester fiber used in the present application, the endothermic peak is one, but depending on the fiber structure, two or more peaks are sometimes observed. In this case, the half-peak width is set to the value obtained by summing the half-peak widths of the respective peaks. In order to set the half-peak width to 15°C or more, a method in which, for example, a liquid crystalline polyester fiber subjected to solid-phase polymerization is heat-treated at a high temperature higher than the melting point can be cited.

[0108] The melting point (Tml) of the mesh fabric comprising the liquid crystalline polyester fiber used in the present application is preferably 290°C or more, more preferably 300°C or more, and further preferably 310°C or more. By having such a high melting point, the heat resistance as a mesh is excellent. The upper limit of the melting point is around 400°C. Note that the melting point referred to in the present application is set to the value obtained by the method described in item (6) of the Examples.

[0109] In the present application, the heat of fusion ΔHml of the mesh fabric is preferably 6.0 J / g or less. By lowering ΔHml to 6.0 J / g or less, it is indicated that the crystallinity is low, the fibril structure is disordered, the fiber as a whole is softened, and the fiber is easily collapsed in the transverse direction (fiber axis perpendicular direction). The lower ΔHml is, the more easily the fiber is collapsed in the transverse direction (fiber axis perpendicular direction), and therefore, it is more preferable to be 5.0 J / g or less. The lower limit of ΔHml is around 0.1 J / g. Note that ΔHml referred to in the present application is set to the value obtained by the method described in item (6) of the Examples. In order to make the heat of fusion ΔHml of the mesh fabric 6.0 J / g or less, a method in which, for example, a liquid crystalline polyester fiber subjected to solid-phase polymerization is heat-treated at a high temperature higher than the melting point can be cited.

[0110] The mesh fabric containing liquid crystalline polyester fibers or polyphenylene sulfide fibers used in the present application preferably has a tensile strength of 200 N / 5 cm or more. With respect to the mesh fabric containing liquid crystalline polyester fibers or polyphenylene sulfide fibers, if the tensile strength is 200 N / 5 cm or more, the strength is sufficiently high and the reinforcing properties are excellent. From this viewpoint, the higher the tensile strength, the better, and more preferably 300 N / 5 cm or more. The upper limit of the tensile strength is about 1000 N / 5 cm. Note that the tensile strength referred to in the present application is the value obtained by the method described in item (7) of the Examples.

[0111] Here, the effects of the mesh fabric used in the present application are described from the viewpoint of mesh characteristics. It is believed that in the present application, the mesh fabric functions mainly as a reinforcing material. As a reinforcing material, the ideal form is thin, has a large opening portion, and has excellent mechanical properties, thermal properties, and chemical resistance. In the present application, first, by using the mesh fabric, the fibers are connected in the warp and weft directions, and high mechanical properties can be exhibited relative to the amount of fibers used. Next, as mesh characteristics, by having a yarn thickness / fiber diameter of less than 2.0, the yarn thickness is thin relative to the fiber diameter, and by having an opening size / fiber diameter of more than 1.0, the opening portion is large, so when used as a reinforcing material for an electrolyte membrane, it is possible to improve the mechanical strength while maintaining proton conduction.

[0112] In the present application, as the fiber constituting the mesh fabric, a liquid crystalline polyester fiber or a polyphenylene sulfide fiber is used.

[0113] As a feature of the case where a liquid crystalline polyester fiber is used, the thermal properties, chemical resistance required for an ideal reinforcing material are possessed, and the fiber has high strength and elastic modulus, so even in the case where the yarn thickness is thin and the opening portion is large, excellent reinforcing properties can be obtained. Furthermore, as a synergistic effect, the present inventors have found that a liquid crystalline polyester fiber is easily collapsed in the lateral direction (fiber axis perpendicular direction), and by controlling the fiber structure, the properties are improved. By effectively utilizing this feature, it is possible to further thin the mesh fabric, and when used as a reinforcing material for an electrolyte membrane, it is easy to obtain the mechanical strength required as an electrolyte membrane in an electrochemical hydrogen pump or a water electrolysis device without impairing the proton conduction of the membrane. It is believed that, as described above, the feature in the case where a liquid crystalline polyester fiber is used is that excellent heat resistance, chemical resistance, and high strength can be combined, and a thin mesh fabric having a yarn thickness of 50 μm or less, particularly a yarn thickness of 40 μm or less, can also be obtained.

[0114] Further, as a feature in the case of using polyphenylene sulfide fibers, on the basis of excellent thermal properties and drug resistance, it is possible to cite that it is easy to obtain fibers having a small fiber diameter. In this regard, the following reasons can be considered. That is, the melting point of polyphenylene sulfide is not excessively high, and thus it is possible to perform fiber production in a process that does not require an excessively high temperature in melt spinning, particularly heat stretching. Thus, it is possible to improve the uniformity of temperature and improve the stability of fiber production. Thus, it is considered that it becomes easy to obtain fibers having a small fiber diameter. As described above, it is considered that a feature in the case of using polyphenylene sulfide fibers is that it is easy to obtain fibers having a small fiber diameter, and thus it is possible to further thin the mesh fabric.

[0115] [Composite layer]

[0116] The composite electrolyte membrane of the present application has a composite layer in which the aforementioned high molecular electrolyte is compounded with the aforementioned mesh fabric containing liquid crystalline polyester fibers or polyphenylene sulfide fibers. The high molecular electrolyte is filled in the voids of the mesh fabric by compounding. The filling rate of the high molecular electrolyte in the composite layer is preferably 40% or more, and more preferably 50% or more. If the filling rate of the composite layer is reduced, the proton conduction path is lost, and thus the power generation performance is reduced. Note that the filling rate of the composite layer in the present application is a value calculated from IEC, and specifically, it is measured according to the method described in item (8) of the Examples.

[0117] The composite electrolyte membrane can be formed of one layer of the composite layer, or can be stacked with two or more layers of the composite layer. At the time of stacking, a plurality of composite layers having different filling rates can be stacked. Further, a layer formed of only a high molecular electrolyte material can be provided so as to be in contact with both sides or one side of the composite layer. By having such a layer, it is possible to improve the adhesion of the composite electrolyte membrane to the electrode, and it is possible to suppress interface peeling.

[0118] The composite electrolyte membrane of the present application can easily reduce the dimensional change rate in the plane direction by having the composite layer. By reducing the dimensional change rate in the plane direction, it is possible to suppress deformation of the membrane due to swelling when used as an electrolyte membrane for an electrochemical hydrogen pump or a water electrolysis device, and thus it is possible to improve the durability. The dimensional change rate in the plane direction λxy of the composite electrolyte membrane is preferably 10% or less, more preferably 8% or less, and further preferably 5% or less.

[0119] In addition, the dimensional change ratio in the plane direction of the composite electrolyte membrane is preferably small in anisotropy in the MD and TD directions. In the case of large anisotropy, the design of the cell unit of the electrolyte membrane of the electrochemical hydrogen pump or water electrolysis device is sometimes restricted, or the stress applied to the membrane becomes biased due to the unevenness of the deformation of the membrane, and the electrolyte membrane is broken from that portion. Specifically, the ratio λMD / λTD of the dimensional change ratio λMD in the MD direction to the dimensional change ratio λTD in the TD direction in the plane direction of the composite electrolyte membrane preferably satisfies 0.25 < λMD / λTD < 4.0. Here, MD is the direction in which the membrane is formed, and TD is the direction perpendicular to MD.

[0120] Here, the dimensional change ratio λ is an index indicating the change in the size of the composite electrolyte membrane in the dry state to the size of the composite electrolyte membrane after immersion in hot water at 80°C, and the specific measurement is performed according to the method described in item (9) of the Examples.

[0121] The composite electrolyte membrane of the present application uses a mesh fabric containing liquid crystalline polyester fibers or polyphenylene sulfide fibers that are high in strength even in hot water at 80°C, and thus has high mechanical strength when used as an electrolyte membrane of an electrochemical hydrogen pump or water electrolysis device, thereby enabling improvement in durability. The tensile strength of the composite electrolyte membrane in hot water at 80°C is preferably 50 MPa or more, more preferably 70 MPa or more. In addition, the elastic modulus in hot water at 80°C is preferably 100 MPa or more, more preferably 300 MPa or more, and further preferably 500 MPa or more. Here, the specific measurement of the tensile strength and the elastic modulus of the composite electrolyte membrane in hot water at 80°C is performed according to the method described in item (10) of the Examples.

[0122] The composite electrolyte membrane of the present application uses a mesh fabric containing liquid crystalline polyester fibers having high acid resistance, and thus the produced composite electrolyte membrane also has high acid resistance. Under the operating conditions of an electrochemical hydrogen pump or water electrolysis device, the electrolyte membrane is exposed to an acidic condition, and thus the use of the composite electrolyte membrane of the present application having high acid resistance enables improvement in durability. The acid resistance S of the composite electrolyte membrane is preferably 60% or more, more preferably 80% or more, and further preferably 90% or more. Here, the acid resistance S is an index indicating the oxidative deterioration of the electrolyte membrane before and after exposure of the composite electrolyte membrane to an acidic condition, and the specific measurement is performed according to the method described in item (11) of the Examples.

[0123] The thickness of the composite layer in the composite electrolyte membrane of the present application is not particularly limited, and is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less. In the case of a thick composite layer, there is a tendency that the physical durability of the electrolyte membrane is improved, whereas the membrane resistance increases. In contrast, in the case of a thin composite layer, there is a tendency that the chemical hydrogen pump performance and the water electrolysis performance are improved, whereas the physical durability becomes problematic, and problems such as electrical short-circuiting and fuel permeation are likely to occur.

[0124] <Method for producing composite electrolyte membrane>

[0125] The composite electrolyte membrane of the present application can be produced, for example, by the following method for producing a composite electrolyte membrane, which is characterized by sequentially including the following steps: a step of compounding a mesh fabric including liquid crystalline polyester fibers and a polymer electrolyte in a state where ionic groups contained in the polymer electrolyte form a salt with cations of an alkali metal or an alkaline earth metal; and a step of exchanging the cations of the alkali metal or the alkaline earth metal that form a salt with the ionic groups with protons. Hereinafter, the production method will be described. Note that in the present specification, the polymer electrolyte in a state where ionic groups form a salt with cations of an alkali metal or an alkaline earth metal is referred to as a "salt-type polymer electrolyte".

[0126] As a method for compounding the mesh fabric and the salt-type polymer electrolyte, a method in which the mesh fabric is impregnated with a solution of the salt-type polymer electrolyte, and then the solvent is dried to produce a composite electrolyte membrane is preferred. As a method for impregnating the mesh fabric with a solution of the salt-type polymer electrolyte, the following methods can be given: (1) a method in which the mesh fabric impregnated with a solution of the salt-type polymer electrolyte is pulled up while removing excess solution to control the film thickness; (2) a method in which the solution of the salt-type polymer electrolyte is cast onto the mesh fabric; and (3) a method in which the mesh fabric is attached to a support substrate on which the solution of the salt-type polymer electrolyte is cast to impregnate.

[0127] As for the drying of the solvent, in the case where impregnation is performed by the method of (3), the drying of the solvent can be performed as it is. In the case where impregnation is performed by the method of (1) or (2), from the viewpoint of improving the quality of the membrane by reducing wrinkles, uneven thickness, and the like of the composite electrolyte membrane, it is preferable to dry the solvent of the polymer electrolyte material in a state where a mesh fabric is attached to a support substrate prepared separately. The drying time and the drying temperature of the mesh fabric are appropriately determined depending on the experiment, and it is preferable to dry at least to a degree where a self-supporting membrane can be obtained even after peeling from the substrate. As the method of drying, known methods such as heating of the substrate, hot air, an infrared heater, and the like can be selected. From the viewpoint of decomposition of the polymer electrolyte, the drying temperature is preferably 200°C or lower, and more preferably 130°C or lower.

[0128] The solvent used in the polymer electrolyte solution of the salt type can be appropriately selected depending on the polymer species. As the solvent, for example, it is preferable to use aprotic polar solvents such as N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, sulfolane, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoric triamide, and the like; ester-based solvents such as γ-butyrolactone, ethyl acetate, butyl acetate, and the like; carbonate-based solvents such as ethylene carbonate, propylene carbonate, and the like; and alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and the like. In addition, a mixed solvent obtained by mixing two or more of these solvents can be used.

[0129] In addition, in order to adjust the viscosity, various low-boiling solvents described below can also be mixed in the solvent: alcohol-based solvents such as methanol, ethanol, 1-propanol, isopropanol, and the like; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and the like; ester-based solvents such as ethyl acetate, butyl acetate, ethyl lactate, and the like; hydrocarbon-based solvents such as hexane, cyclohexane, and the like; aromatic hydrocarbon-based solvents such as benzene, toluene, xylene, and the like; halogenated hydrocarbon-based solvents such as chloroform, dichloromethane, 1,2-dichloroethane, perchloroethylene, chlorobenzene, dichlorobenzene, hexafluoroisopropanol, and the like; ether-based solvents such as diethyl ether, tetrahydrofuran, 1,4-dioxane, and the like; nitrile-based solvents such as acetonitrile, and the like; nitrohydrocarbon-based solvents such as nitromethane, nitroethane, and the like; water; and the like.

[0130] The concentration of the salt-type polymer electrolyte solution used is preferably 5 to 40% by weight, and more preferably 10 to 30% by weight. If the concentration is within this range, the polymer electrolyte can be sufficiently filled into the voids of the mesh fabric, and a composite layer having excellent surface smoothness can be obtained. If the concentration of the salt-type polymer electrolyte solution is too low, the filling efficiency of the polymer electrolyte into the voids of the mesh fabric decreases, and sometimes multiple impregnation processes are required. On the other hand, if the concentration of the polymer electrolyte solution is too high, the solution viscosity is sometimes too high, the polymer cannot be sufficiently filled into the voids of the mesh fabric, the filling rate in the composite layer decreases, or the surface smoothness of the composite electrolyte membrane deteriorates.

[0131] Note that the solution viscosity of the salt-type polymer electrolyte solution is preferably 100 to 50,000 mPa-s, and more preferably 500 to 10,000 mPa-s. If the solution viscosity is too low, the solution has poor retention, and sometimes leaks from the mesh fabric. On the other hand, in the case where the solution viscosity is too high, the above-mentioned problems sometimes occur.

[0132] As the method of casting the salt-type polymer electrolyte solution, blade coating, direct roll coating, Meyer bar coating, gravure coating, reverse coating, air knife coating, spray coating, brush coating, dip coating, die coating, vacuum die coating, curtain coating, flow coating, spin coating, screen printing, inkjet coating, and the like can be used.

[0133] In the present production method, after the salt-type polymer electrolyte is compounded with the mesh fabric, a process of exchanging the protons of the alkali metal or alkaline earth metal cations that form a salt with the ionic groups is included. This process is preferably a process of bringing the composite layer of the mesh fabric and the salt-type polymer electrolyte material into contact with an acidic aqueous solution. Further, this contact is more preferably a process of immersing the composite layer in an acidic aqueous solution. In this process, the protons in the acidic aqueous solution are replaced with cations that ionically bond with the ionic groups, and at the same time, water-soluble impurities, residual monomers, solvents, residual salts, and the like are removed. The acidic aqueous solution is not particularly limited, and sulfuric acid, hydrochloric acid, nitric acid, acetic acid, trifluoromethanesulfonic acid, methanesulfonic acid, phosphoric acid, citric acid, and the like are preferably used. The temperature, concentration, and the like of the acidic aqueous solution should be appropriately determined, but from the viewpoint of productivity, it is preferable to use a sulfuric acid aqueous solution having a concentration of 3% by weight or more and 30% by weight or less at a temperature of 0°C or higher and 80°C or lower.

[0134] For the purpose of improving mechanical strength and improving thermal stability of ionic groups, improving water resistance, improving solvent resistance, improving radical resistance, improving coatability of a coating liquid, improving storage stability, and the like, a cross-linking agent, a crystallization nucleating agent used in general high molecular compounds, a plasticizer, a stabilizer, a release agent, an antioxidant, a radical scavenger, inorganic microparticles, and the like can be added to the composite electrolyte membrane without departing from the object of the present application.

[0135] As described above, the composite electrolyte membrane of the present application can maintain sufficient mechanical strength even under a high humidity and high pressure condition which is an operating condition of an electrochemical hydrogen pump or a water electrolysis device. In the present specification, the maintenance of sufficient mechanical strength means that at least one of tensile strength and elastic modulus is good. Both of the tensile strength and the elastic modulus are preferably good.

[0136] By at least one of the tensile strength and the elastic modulus being good, and preferably both of them being good, it is easy to make the size change ratio λxy in the plane direction small.

[0137] In addition, the liquid crystal polyester fiber or the polyphenylene sulfide fiber as the fiber constituting the mesh fabric is a fiber having high chemical resistance, and thus, even if the electrochemical hydrogen pump or the water electrolysis device, and the like, in which the composite electrolyte membrane of the present application is continuously used for a long time, is operated, the mechanical properties are not easily reduced. Note that in the present application, the chemical resistance is evaluated by the acid resistance test described in Example (11).

[0138] The composite electrolyte membrane of the present application can be used for various uses. For example, it can be used for medical uses such as artificial skin, filtration uses, ion exchange resin uses such as chlorine-resistant reverse osmosis membranes, various structural material uses, electrochemical uses, humidifying membranes, anti-fogging membranes, anti-static membranes, deoxidizing membranes, solar cell membranes, and gas barrier membranes. Among them, it can be more preferably used for various electrochemical uses. As the electrochemical uses, for example, a solid polymer fuel cell, a redox flow battery, an electrochemical hydrogen pump, a water electrolysis device, a hydrogen refiner, a chlor-alkali electrolysis device, and the like can be exemplified. The electrolyte membrane of the present application can achieve sufficient mechanical strength even under a high humidity and high pressure condition which is an operating condition of an electrochemical hydrogen pump or a water electrolysis device, and can achieve high hydrogen compression performance or water electrolysis performance, and thus, it is particularly preferably used for an electrochemical hydrogen pump and a water electrolysis device.

[0139] <Electrolyte membrane with catalyst layer, membrane electrode composite, and electrochemical hydrogen pump and water electrolysis device>

[0140] The electrochemical hydrogen pump of the present application and the water electrolysis device of the present application are made using the composite electrolyte membrane of the present application. That is, the cell unit used in the electrochemical hydrogen pump and the water electrolysis device of the present application has a structure in which a catalyst layer, an electrode substrate, and a separator are sequentially stacked on both surfaces of the composite electrolyte membrane of the present application.

[0141] In the above structure, the electrolyte membrane with catalyst layer of the present application has catalyst layers on both sides of the composite electrolyte membrane of the present application. That is, the electrolyte membrane with catalyst layer of the present application (hereinafter, CCM) is an electrolyte membrane in which catalyst layers are laminated on both sides of the composite electrolyte membrane (i.e., the layer structure of catalyst layer / composite electrolyte membrane / catalyst layer).

[0142] In addition, in the above structure, the membrane electrode composite of the present application contains the composite electrolyte of the present application. That is, the membrane electrode composite of the present application (hereinafter, MEA) has catalyst layers and gas diffusion substrates sequentially laminated on both sides of the composite electrolyte membrane (i.e., the layer structure of gas diffusion substrate / catalyst layer / composite electrolyte membrane / catalyst layer / gas diffusion substrate).

[0143] As a method for producing the CCM, the following methods are generally performed: a coating method in which a catalyst layer paste composition for forming a catalyst layer is applied on the surface of the composite electrolyte membrane and dried; and a transfer method in which only a catalyst layer is produced on a substrate, and the catalyst layer is transferred to laminate the catalyst layer on the composite electrolyte membrane.

[0144] In the case of producing an MEA by pressurization, known methods (for example, a chemical plating method described in Electrochemistry, 1985, 53, p. 269. (J. Electrochem. Soc.); a hot press bonding method of a gas diffusion electrode described in Electrochemical Science and Technology, 1988, 135, 9, p. 2209. etc.) can be applied. The temperature and pressure at the time of pressurization can be appropriately selected depending on the thickness, moisture content, catalyst layer, and electrode substrate of the composite electrolyte membrane. In the present application, even in the case of a dried state or a water-absorbed state of the electrolyte membrane, the composite can be formed based on pressurization. As a specific pressurization method, roll pressurization in which the pressure and gap are defined, flat plate pressurization in which the pressure is defined, etc. can be exemplified. From the viewpoint of industrial productivity, suppression of thermal decomposition of a high molecular material having an ionic group, etc., the pressurization is preferably performed in the range of 0°C to 250°C. From the viewpoint of protecting the composite electrolyte membrane and the electrode, the pressurization is preferably as weak as possible within a range in which the adhesion of the composite electrolyte membrane and the catalyst layer can be maintained. In the case of flat plate pressurization, the pressure is preferably 10 MPa or less. From the viewpoint of preventing short circuit of the anode and cathode electrodes, one of the preferable options is to overlap the electrode and the electrolyte membrane without performing the composite formation based on the pressurization process to perform cell unitization for electrochemical hydrogen pump and water electrolysis device applications. In the case of this method, in the case of repeated operation as an electrochemical hydrogen pump and a water electrolysis device, there is a tendency that the deterioration of the electrolyte membrane, which is presumed to be the cause of the short circuit site, is suppressed, and the durability as an electrochemical hydrogen pump and a water electrolysis device becomes good. In the control of the pressurization conditions, in terms of obtaining a uniform catalyst layer-equipped electrolyte membrane without wrinkles or peeling, it is preferable to increase the temperature after pressurization, maintain a predetermined pressure and temperature, and then decrease the temperature while maintaining the pressure, and then release the pressure. If the temperature is increased while pressurization is performed, or the pressure is released before the temperature is decreased, sometimes three-dimensional thermal shrinkage occurs in a state in which the interface of the composite electrolyte membrane and the catalyst layer is not fixed, and peeling due to wrinkles or poor adhesion occurs.

[0145] Example

[0146] Hereinafter, the present application will be further explained in detail by examples, but the present application is not limited to them.

[0147] The measurement conditions of each property are described below.

[0148] (1) Molecular weight of polymer

[0149] The number average molecular weight and the weight average molecular weight of the polymer solution were measured by GPC. Using HLC-8022 GPC manufactured by Tosoh Corporation as an integrated device of an ultraviolet detector and a differential refractometer, in addition, using two TSK gel Super HM-H manufactured by Tosoh Corporation (inner diameter 6.0 mm, length 15 cm) as GPC columns, measurement was performed at a flow rate of 0.2 mL / min using N-methyl-2-pyrrolidone solvent (N-methyl-2-pyrrolidone solvent containing 10 mmol / L lithium bromide), and the number average molecular weight and the weight average molecular weight were calculated based on standard polystyrene.

[0150] (2) Ion Exchange Capacity (IEC)

[0151] The measurement was performed by neutralization titration method. The measurement was performed three times, and the average value was taken.

[0152] 1. After the water on the membrane surface of the composite electrolyte membrane sufficiently washed with pure water was wiped off by proton replacement, the membrane was vacuum-dried at 100°C for 12 hours or more, and the dried weight was obtained.

[0153] 2. Ion exchange was performed by adding 50 mL of 5 wt% sodium sulfate aqueous solution to the electrolyte and standing for 12 hours.

[0154] 3. The generated sulfuric acid was titrated using 0.01 mol / L sodium hydroxide aqueous solution. A commercially available phenothalin solution 0.1 w / v% was used as an indicator, and the point at which the color became light purple was taken as the end point.

[0155] 4. The IEC was obtained by the following formula.

[0156] IEC (meq / g) = (concentration of sodium hydroxide aqueous solution (mmol / ml) x amount of addition (ml)) / dried weight of the sample (g)

[0157] (3) Membrane Thickness

[0158] The measurement was performed using ID-C112 manufactured by Mitutoyo Corporation installed in a granite comparator stand BSG-20 manufactured by Mitutoyo Corporation.

[0159] Regarding the membrane thickness, the electrolyte membrane or the reinforcing material was cut into 10 cm square, and the positions at a distance of 5 cm from the end in the MD direction and at a distance of 1 cm, 3 cm, 5 cm, 7 cm, 9 cm from the end in the TD direction, and the positions at a distance of 5 cm from the end in the TD direction and at a distance of 1 cm, 3 cm, 5 cm, 7 cm, 9 cm from the end in the MD direction were measured, and the average value of the nine points was obtained. The average value was defined as the membrane thickness of the electrolyte membrane.

[0160] (4) Fiber diameter, opening, OPA, transmission volume of the mesh fabric

[0161] The mesh fabric was cut into 100 mm square, and a microscope VHX-2000 manufactured by KEYENCE CORPORATION was used to measure the fiber diameter and the opening. As for the measurement position, the approximately middle point between the intersection of the fibers constituting the mesh was set. The fiber diameter and the opening were measured at 10 different places in the mesh fabric, and the value obtained by averaging them was used as the fiber diameter (μm) and the opening (μm). As for the mesh count, the following formula was used to calculate it.

[0162] Mesh count (root / inch) = 25400 / (opening (μm) + fiber diameter (μm))

[0163] As for the OPA, the following formula was used to calculate it.

[0164] OPA (%) = {opening (μm) 2 / (opening + fiber diameter (μm)) 2} x 100

[0165] The transmission volume was calculated using the thickness of the yarn (μm) obtained in item (5) and the following formula.

[0166] Transmission volume (cc / m 2 ) = (OPA (%) / 100) x thickness of the yarn (μm).

[0167] (5) Thickness of the yarn of the mesh fabric

[0168] The mesh fabric was cut into 100 mm square, and a digital indicator manufactured by Mitutoyo Corporation was used to measure it. The measurement was performed at 9 different places in the mesh fabric, and the value obtained by averaging them was used as the thickness of the yarn (μm).

[0169] (6) Thermal properties of the polymer and the mesh fabric

[0170] Differential thermal analysis was performed using a DSC 2920 manufactured by TA instruments. The temperature of the endothermic peak observed when the measurement was performed at a temperature increase of 20°C / minute from 50°C was set as Tm1 (°C), and the half-peak width (°C) of Tm1 and the heat of fusion ΔHm1 (J / g) at Tm1 were measured. In addition, after the observation of Tm1, the temperature was maintained at Tm1 + 20°C for 5 minutes, and then temporarily cooled to 50°C at a temperature decrease of 20°C / minute, and the measurement was performed again at a temperature increase of 20°C / minute, and the temperature of the endothermic peak observed at this time was set as Tm2. As for the resin of the reference example, Tm2 was used as the melting point.

[0171] (7) Tensile strength of the mesh fabric

[0172] The tensile test was performed in accordance with JIS L1913 (2010) 6.3.1 under the conditions of a sample size of 5 cm x 30 cm, a cloth clamp interval of 20 cm, and a tensile speed of 10 cm / minute, n = 3. The strength at the time of sample breakage was set as the tensile strength (N / 5 cm), the average value was calculated, and the value obtained by rounding off the second decimal place was used as the tensile strength (N / 5 cm).

[0173] (8) Filling rate of the polymer electrolyte in the composite layer

[0174] The cross section of the composite electrolyte membrane was observed with an optical microscope or a scanning electron microscope (SEM). The thickness of the composite layer including the polymer electrolyte and the mesh fabric was set as T1, and the thickness of other layers on the outside of the composite layer was set as T2, T3 when they were present. The specific gravity of the polymer forming the composite layer was set as D1, and the specific gravity of the polymer forming the other layers on the outside of the composite layer was set as D2, D3, respectively. The specific gravity of the composite electrolyte membrane was set as D. The IEC of the polymer forming each layer was set as I1, I2, I3, and the IEC of the composite electrolyte membrane was set as I, and the content rate Y (vol%) of the polymer electrolyte in the composite layer was calculated by the following formula.

[0175] Y = [(T1+T2+T3) x D x I - (T2 x D2 x I2+T3 x D3 x I3)] / (T1 x D1 x I1) x 100

[0176] (9) Dimensional change rate (λxy) by hot water test

[0177] The composite electrolyte membrane was cut into a square of about 5 cm x about 5 cm, and after being left to stand in a temperature-controlled and humidity-controlled atmosphere at a temperature of 23°C ± 5°C and a humidity of 50% ± 5% for 24 hours, the length in the MD direction and the length in the TD direction (MD1 and TD1) were measured with a vernier caliper. After the electrolyte membrane was immersed in hot water at 80°C for 8 hours, the length in the MD direction and the length in the TD direction (MD2 and TD2) were measured again with a vernier caliper, and the dimensional change rates (λMD and λTD) in the MD direction and the TD direction in the plane direction and the dimensional change rate (λxy) (%) in the plane direction were calculated by the following formula.

[0178] λMD = (MD2 - MD1) / MD1 x 100

[0179] λTD = (TD2 - TD1) / TD1 x 100

[0180] λxy = (λMD + λTD) / 2

[0181] (10) Mechanical strength measurement in hot water

[0182] After the electrolyte membrane as a test piece was left in ultrapure water at 80°C for 24 hours, it was placed in the device and tensile testing was performed under the following conditions. The values of tensile strength and tensile elongation were set to the values at the instant at which the maximum stress was shown in the test. The elastic modulus was set to the maximum value calculated using any two points with a difference in strain of 1%. The maximum stress and the elastic modulus were calculated as the average of 5 tests.

[0183] Measuring device: AUTOGRAPH AG-IS (manufactured by Shimadzu Corporation)

[0184] Load: 100 N

[0185] Tensile speed: 10 mm / min

[0186] Test piece: 5 mm wide x 50 mm long

[0187] Distance between samples: 20 mm

[0188] Test temperature: 80°C, in pure water

[0189] Number of tests: n = 5

[0190] (11) Acid resistance test

[0191] Tensile testing was performed on a test piece immersed in 10 wt% sulfuric acid at 80°C for 30 days and on a composite electrolyte membrane that had not been immersed, using the method described in (10). The tensile strength of the test piece that had not been immersed was set to A, the tensile strength of the test piece after immersion was set to B, and the acid resistance S was calculated by the following equation.

[0192] S = (A - B) x 100

[0193] (12) Production of catalyst layer-equipped electrolyte membrane (CCM)

[0194] A catalyst ink obtained by adjusting a platinum catalyst TEC10E50E manufactured by Tanaka Kikinzoku Kogyo K.K. and "Nafion (registered trademark)" manufactured by DuPont Company in a weight ratio of 2:1 was applied to a commercially available "Teflon (registered trademark)" film so that the amount of platinum would be 0.3 mg / cm 2 A catalyst layer transfer film A100 was produced. One pair of films obtained by cutting the catalyst layer transfer film into 5 cm squares was prepared, and they were overlaid so that they would sandwich the polymer electrolyte membrane to be evaluated, and were heated and pressurized at 150°C and 5 MPa for 3 minutes in a pressurized state, were cooled to 40°C or lower in a pressurized state, and then the pressure was released, to obtain a catalyst layer-equipped electrolyte membrane for an electrochemical hydrogen pump.

[0195] In addition, a catalyst ink obtained by adjusting the iridium oxide catalyst manufactured by Umicore S.A. and "Nafion (registered trademark)" manufactured by DuPont Company in a weight ratio of 2:1 was applied to a commercially available Teflon film in a manner such that the amount of iridium reached 2.5 mg / cm 2 A catalyst layer transfer film A200 was produced by coating the catalyst ink on a commercially available Teflon film in a manner such that the amount of iridium reached 2.5 mg / cm

[0196] (13) Production of a membrane electrode assembly (MEA)

[0197] One pair of electrodes obtained by cutting a commercially available gas diffusion electrode 24BCH manufactured by SGL into a square of 5 cm was prepared, and the electrodes were overlapped so as to sandwich the catalyst layer-equipped electrolyte membrane for a water electrolysis device, to obtain a membrane electrode assembly for an electrochemical hydrogen pump.

[0198] In addition, one pair of commercially available porous titanium sintered body plates was used to sandwich the catalyst layer-equipped electrolyte membrane for a water electrolysis device, to obtain a membrane electrode assembly for a water electrolysis device.

[0199] (14) Hydrogen compression evaluation

[0200] The membrane electrode assembly for an electrochemical hydrogen pump was placed in a JARI standard cell unit "Ex-1" (electrode area 25 cm 2 The cell unit temperature was set to 40°C, and hydrogen humidified to 100% RH was supplied to one electrode (hydrogen supply electrode: cathode) at a flow rate of 1 L / min under atmospheric pressure.

[0201] The other electrode (hydrogen compression electrode: anode) was configured so that the pressure could be controlled using a back pressure valve, and was evaluated by purging with 100% RH nitrogen in a manner such that the pressure reached atmospheric pressure before the hydrogen compression evaluation.

[0202] The nitrogen exhaust valve of the hydrogen compression electrode was closed before the hydrogen compression evaluation, and a small direct current power supply KX-100L manufactured by Takasago Manufacturing Co., Ltd. was used to output a load current of 10 A until the back pressure of the hydrogen compression electrode reached 10 MPa in terms of gage pressure. The pressure was maintained at 10 MPa for 10 hours. The membrane electrode assembly after the evaluation was placed in a bubbling leak test jig immersed in water, nitrogen was caused to flow from one side of the membrane electrode assembly, and the presence or absence of nitrogen leaking from the other side was observed, whereby the presence or absence of a membrane rupture was confirmed.

[0203] (15) Water electrolysis evaluation

[0204] The aforementioned water electrolysis device membrane electrode assembly was installed in a JARI standard cell unit "Ex-1" (electrode area 25 cm 2 ) manufactured by Eiwa Co., Ltd., the cell unit temperature was set to 80°C, and a conductivity of 1 μS cm -1 The following pure water.

[0205] The other electrode (hydrogen generation electrode: cathode) was made so as to be able to control the pressure using a back pressure valve, and prior to the evaluation, purging was performed using nitrogen gas of 100% RH in such a manner as to reach atmospheric pressure.

[0206] A Multistat 1480 and a Power booster Model PBi500L-5U manufactured by Solartron Metrology were used to output a load current of 50 A (current density 2 A / cm 2 ) at atmospheric pressure. After the current was maintained for 10 hours, the cell unit voltage at that time was measured. The lower the cell unit voltage, the more excellent the water electrolysis efficiency.

[0207] [Synthesis Example 1] Synthesis of block copolymer b1

[0208] (Synthesis of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane (K-DHBP) represented by the following formula (G1))

[0209] [Chemical Formula 3]

[0210]

[0211] In a 500 mL flask equipped with a stirrer, a thermometer, and a distillation tube, 49.5 g of 4,4'-dihydroxybenzophenone, 134 g of ethylene glycol, 96.9 g of trimethyl orthoformate, and 0.50 g of p-toluenesulfonic acid monohydrate were put in and dissolved. Then, the temperature was kept at 78 to 82°C for 2 hours while stirring. Further, the internal temperature was slowly increased to 120°C, and heating was performed until the distillation of methyl formate, methanol, and trimethyl orthoformate completely stopped. After the reaction solution was cooled to room temperature, the reaction solution was diluted with ethyl acetate, the organic layer was washed with 100 mL of a 5% potassium carbonate aqueous solution and was separated, and the solvent was distilled off. Crystallization was performed by adding 80 mL of dichloromethane to the residue, and filtration and drying were performed, thereby obtaining 52.0 g of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane.

[0212] (Synthesis of 3,3'-disodium disulfonate-4,4'-difluorobenzophenone represented by the following formula (G2))

[0213] [Chemical Formula 4]

[0214]

[0215] A mixture of 109.1 g of 4,4'-difluorobenzophenone (Aldrich reagent) was reacted in 150 mL of fuming sulfuric acid (50% SO3) (and light pure drug reagent) at 100°C for 10 hours. Thereafter, a small amount was gradually added to a large amount of water, and after neutralization with NaOH, 200 g of common salt was added to precipitate the product. The obtained precipitate was filtered, recrystallized from an ethanol aqueous solution, and 3,3'-disodium disulfonate-4,4'-difluorobenzophenone represented by the above general formula (G2) was obtained.

[0216] (Synthesis of an ionic group-free oligomer a1' represented by the following formula (G3))

[0217] In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 16.59 g of potassium carbonate (Aldrich reagent, 120 mmol), 25.8 g (100 mmol) of K-DHBP, and 20.3 g of 4,4'-difluorobenzophenone (Aldrich reagent, 93 mmol) were added. After nitrogen substitution, dehydration was performed at 160°C in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, and toluene was removed by heating. Polymerization was performed at 180°C for 1 hour. Purification was performed by reprecipitation in a large amount of methanol, and an ionic group-free oligomer al (terminal hydroxyl group) was obtained. The number average molecular weight was 10000.

[0218] In a 500 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 1.1 g of potassium carbonate (Aldrich reagent, 8 mmol), and 20.0 g (2 mmol) of the above ionic group-free oligomer al (terminal hydroxyl group) were added. After nitrogen substitution, dehydration was performed at 100°C in 100 mL of NMP and 30 mL of cyclohexane, and cyclohexane was removed by heating. 4.0 g of decafluorobiphenyl (Aldrich reagent, 12 mmol) was added, and reaction was performed at 105°C for 1 hour. Purification was performed by reprecipitation in a large amount of isopropyl alcohol, and an ionic group-free oligomer a1' (terminal fluoro group) represented by the following formula (G3) was obtained. The number average molecular weight was 11000, and the number average molecular weight of the ionic group-free oligomer a1' was calculated as 10400 by subtracting the molecular weight of the linking site (630).

[0219] [Chemical Formula 5]

[0220]

[0221] (Synthesis of ion-containing oligomer a2 represented by the following formula (G4))

[0222] In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 27.6 g of potassium carbonate (Aldrich reagent, 200 mmol), 12.9 g (50 mmol) of K-DHBP, and 9.3 g of 4,4'-biphenol (Aldrich reagent, 50 mmol), 39.3 g (93 mmol) of 3,3'-disulfonate disodium-4,4'-difluorobenzophenone, and 17.9 g of 18-crown-6 (and optical pure drug 82 mmol) were added. After nitrogen substitution, dehydration was performed at 170°C in 300 mL of NMP and 100 mL of toluene, and toluene was removed by heating. Polymerization was performed at 180°C for 1 hour. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain ion-containing oligomer a2 (terminal hydroxyl group) represented by the following formula (G4). The number average molecular weight was 16000.

[0223] [Chemical Formula 6]

[0224]

[0225] (In formula (G4), M represents Na or K.)

[0226] (Synthesis of block copolymer bl containing ion-containing oligomer a2 as segment (Al), oligomer al as segment (A2) not containing an ion-containing group, and octafluoro- diphenylene as a connecting site)

[0227] In a 500 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 0.56 g of potassium carbonate (Aldrich reagent, 4 mmol), 16 g (1 mmol) of ion-containing oligomer a2 (terminal hydroxyl group) were added. After nitrogen substitution, dehydration was performed at 100°C in 100 mL of NMP and 30 mL of cyclohexane, and cyclohexane was removed by heating. Then, 11 g (1 mmol) of oligomer al' (terminal fluoro group) not containing an ion-containing group was added, and reaction was performed at 105°C for 24 hours. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain block copolymer bl. The weight average molecular weight was 340,000.

[0228] The block copolymer bl itself was used as a polymer electrolyte membrane, immersed in 10 wt% sulfuric acid aqueous solution at 80°C for 24 hours, and subjected to proton substitution and deprotection reaction. Then, the membrane was sufficiently washed by immersion in a large excess of pure water for 24 hours. At this time, the ion exchange capacity was 2.12 meq / g by neutralization titration.

[0229] [Synthesis Example 2] Synthesis of block copolymer b2

[0230] (Synthesis of polyethersulfone (PES) based block copolymer precursor b2' containing segments represented by the following Formula (G6) and segments represented by the following Formula (G7))

[0231] A nickel-containing solution was prepared by mixing 1.78 g of anhydrous nickel chloride and 15 mL of dimethyl sulfoxide, adjusting to 70°C, adding 2.37 g of 2,2'-dipyridyl thereto, and stirring for 10 minutes at the temperature.

[0232] At this time, 1.35 g of zinc powder was added to a solution obtained by dissolving 1.64 g of 2,5-dichlorobenzenesulfonic acid (2,2-dimethylpropyl) ester and 0.55 g of polyethersulfone represented by the following Formula (G5) (SUMIKA EXCEL PES5200P manufactured by Sumitomo Chemical Co., Ltd., Mn = 40,000, Mw = 94,000) in 5 mL of dimethyl sulfoxide, and adjusting to 70°C. The above-described nickel-containing solution was injected thereto, and a polymerization reaction was performed at 70°C for 4 hours. The reaction mixture was added to 60 mL of methanol, and then 60 mL of 6 mol / L hydrochloric acid was added, and stirred for 1 hour. The precipitated solid was separated by filtration, and dried to obtain 1.75 g of a block copolymer precursor b2' (polyarylene precursor) containing segments represented by the following Formula (G6) and segments represented by the following Formula (G7) in off-white color at a yield of 97%. The weight average molecular weight of the obtained polyarylene was 210,000.

[0233] [Chemical Formula 7]

[0234]

[0235] (Synthesis of polyethersulfone (PES) based block copolymer b2 containing segments represented by the aforementioned Formula (G7) and segments represented by the following Formula (G8))

[0236] The block copolymer precursor b2' was added to a mixed solution of 0.18 g of lithium bromide monohydrate and 8 mL of N-methyl-2-pyrrolidone, and reacted at 120°C for 24 hours. The reaction mixture was injected into 80 mL of 6 mol / L hydrochloric acid, and stirred for 1 hour. The precipitated solid was separated by filtration. The separated solid was dried to obtain a block copolymer b2 containing segments represented by Formula (G7) and segments represented by the following Formula (G8) in off-white color. The weight average molecular weight of the obtained polyarylene was 190,000.

[0237] The block copolymer b2 itself was used as a polymer electrolyte membrane, immersed in 10% by weight of an aqueous sulfuric acid solution at 80°C for 24 hours, and after proton exchange, immersed in a large excess of pure water for 24 hours to sufficiently perform washing, and at this time, the ion exchange capacity was 2.02 meq / g by neutralization titration.

[0238] [Chemical Formula 8]

[0239]

[0240] [Synthesis Example 3] Synthesis of block copolymer b3

[0241] (Synthesis of hydrophobic oligomer a3 represented by the following formula (G9))

[0242] [Chemical Formula 9]

[0243]

[0244] In a 1L three-necked flask equipped with a stirrer, a thermometer, a cooling tube, a Dean-Stark tube, and a three-way valve for introducing nitrogen, 51.9g (0.30mol) of 2,6-dichlorobenzonitrile, 92.8g (0.27mol) of 2,2-bis(4-hydroxyphenyl)-l,l,l,3,3,3-hexafluoropropane, and 49.7g (0.36mol) of potassium carbonate were weighed.

[0245] After nitrogen substitution, 363mL of sulfolane and 181mL of toluene were added and stirred. The flask was set in an oil bath, refluxed, and heated to 150°C. While water generated by the reaction was distilled off from the system with the Dean-Stark tube, almost no water was observed to be generated after about 3 hours. After most of the toluene was removed by slowly increasing the reaction temperature, the reaction was continued at 200°C for 3 hours. Next, 12.9g (0.076mol) of 2,6-dichlorobenzonitrile was added and further reacted for 5 hours.

[0246] After the obtained reaction solution was cooled, 100mL of toluene was added and diluted. The precipitate of inorganic compounds generated by the side reaction was removed by filtration, and the filtrate was put into 2L of methanol. The precipitated product was filtered out, recovered, and dried, and then dissolved in 250mL of tetrahydrofuran. This was reprecipitated in 2L of methanol to obtain 109g of the target oligomer. The number average molecular weight of this oligomer was 8000.

[0247] (Synthesis of hydrophilic monomer represented by the following formula (G10))

[0248] [Chemical Formula 10]

[0249]

[0250] In a 3L three-necked flask equipped with a stirrer, a cooling tube, 245 g (2.1 mol) of chlorosulfonic acid was added, followed by 105 g (420 mmol) of 2,5-dichlorobenzophenone, and the mixture was reacted in an oil bath at 100°C for 8 hours. After the prescribed time, the reaction solution was slowly poured into 1000 g of crushed ice, and extracted with ethyl acetate. The organic layer was washed with brine, dried over magnesium sulfate, and then ethyl acetate was distilled off to obtain a yellowish crude crystal of 3-(2,5-dichlorobenzoyl)benzenesulfonyl chloride. The crude crystal was used in the next step without purification.

[0251] To 300 mL of pyridine, 41.1 g (462 mmol) of 2,2-dimethyl-l-propanol (neopentyl alcohol) was added and cooled to about 10°C. To this, the crude crystal obtained in the above was slowly added over about 30 minutes. After the addition of the entire amount, the reaction was further stirred for 30 minutes. After the reaction, the reaction solution was poured into 1000 mL of an aqueous hydrochloric acid solution, and the precipitated solid was recovered. The obtained solid was dissolved in ethyl acetate, washed with an aqueous sodium bicarbonate solution and brine, dried over magnesium sulfate, and then ethyl acetate was distilled off to obtain a crude crystal. This was recrystallized from methanol to obtain white crystals of 3-(2,5-dichlorobenzoyl)benzenesulfonic acid neopentyl ester represented by the above structural formula.

[0252] (Synthesis of polyarylene block copolymer b3 represented by the following formula (Gll))

[0253] [Chemical Formula 11]

[0254]

[0255] In a IL three-necked flask equipped with a stirrer, a thermometer, and a nitrogen inlet tube, 166 mL of dried N,N-dimethylacetamide (DMAc) was added to a mixture of 15.1 g (1.89 mmol) of the aforementioned hydrophobic oligomer a3, 39.5 g (98.4 mmol) of 3-(2,5-dichlorobenzoyl)benzenesulfonic acid neopentyl ester, 2.75 g (4.2 mmol) of bis(triphenylphosphine)nickel dichloride, 11.0 g (42.1 mmol) of triphenylphosphine, 0.47 g (3.15 mmol) of sodium iodide, and 16.5 g (253 mmol) of zinc under nitrogen.

[0256] The reaction system was heated (finally heated to 82°C) with stirring, and the reaction was carried out for 3 hours. An increase in the viscosity of the system was observed midway through the reaction. The polymerization reaction solution was diluted with 180 mL of DMAc, stirred for 30 minutes, and filtered using celite as a filtration aid. In a 1 L three-necked flask equipped with a stirrer, 25.6 g (295 mmol) of lithium bromide was added to the filtrate in three portions of 1 / 3 each at 1 hour intervals, and the reaction was carried out for 5 hours at 120°C under a nitrogen atmosphere. After the reaction, it was cooled to room temperature, poured into 4 L of acetone, and allowed to solidify. The solidified product was collected by filtration, and after air-drying, it was pulverized using a stirrer and washed with 1500 mL of 1 N sulfuric acid while stirring. After filtration, the product was washed with ion exchange water until the pH of the washing liquid reached 5 or more, and then dried at 80°C overnight to obtain the target block copolymer b3. The weight average molecular weight of this block copolymer was 200,000.

[0257] The block copolymer b3 itself was used as a polymer electrolyte membrane, immersed in 10% by weight of an aqueous sulfuric acid solution at 80°C for 24 hours, and after proton exchange, it was immersed in a large excess of pure water for 24 hours to sufficiently wash it. At this time, the ion exchange capacity was 2.38 meq / g as determined by neutralization titration.

[0258] [Synthesis Example 4] Synthesis of Random Copolymer r1

[0259] (Synthesis of Polyketal Ketone Random Copolymer r1 Containing a Monomer Represented by Formula (G1), 4,4'-Difluorobenzophenone, and a Monomer Represented by Formula (G2))

[0260] In a 500 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 13.82 g of potassium carbonate (Aldrich reagent, 100 mmol), 20.66 g (80 mmol) of K-DHBP obtained as an intermediate in the aforementioned Synthesis Example 1, 10.5 g of 4,4'-difluorobenzophenone (Aldrich reagent, 48 mmol), and 13.5 g (32 mmol) of 3,3'-disulfonic acid disodium-4,4'-difluorobenzophenone obtained as an intermediate in the aforementioned Synthesis Example 1 were added, and after nitrogen replacement, dehydration was carried out in 100 mL of N-methylpyrrolidone (NMP), 50 mL of toluene at 180°C, the toluene was removed by heating, and polymerization was carried out at 230°C for 6 hours. Purification was carried out by reprecipitation with a large amount of water to obtain a polyketal ketone random copolymer. The weight average molecular weight was 250,000.

[0261] The random copolymer r1 itself was used as a polymer electrolyte membrane, immersed in 10% by weight of an aqueous sulfuric acid solution at 80°C for 24 hours, and subjected to a proton exchange and deprotection reaction, and then immersed in a large excess of pure water for 24 hours to sufficiently perform washing. At this time, the ion exchange capacity was 1.51 meq / g as determined by neutralization titration.

[0262] [Manufacture Example 1] Manufacture of Mesh Fabric Containing Liquid Crystalline Polyester Fiber

[0263] Into a 5L reaction vessel equipped with a stirring blade and a distillation tube, 870 parts by weight of p-hydroxybenzoic acid, 327 parts by weight of 4,4'-dihydroxydiphenyl, 89 parts by weight of hydroquinone, 292 parts by weight of terephthalic acid, 157 parts by weight of isophthalic acid, and 1460 parts by weight of acetic anhydride (total of phenolic hydroxyl groups: 1.10 equivalents) were charged, and the temperature was raised from room temperature to 145°C over 30 minutes while stirring under a nitrogen atmosphere, and then the reaction was performed at 145°C for 2 hours. Then, the temperature was raised to 335°C over 4 hours.

[0264] The polymerization temperature was maintained at 335°C, and the pressure was reduced to 133 Pa over 1.5 hours. Further, the reaction was continued for 40 minutes, and the polycondensation was completed when the torque reached 28 kgcm. Next, the inside of the reaction vessel was pressurized to 0.1 MPa, the polymer was discharged in the form of a strand through a spinneret having one circular discharge port with a diameter of 10 mm, and the strand was pelletized using a cutter.

[0265] The composition and melting point of the obtained liquid crystalline polyester are shown in Table 1.

[0266] [Table 1]

[0267] [Table 1]

[0268]

[0269] Using this liquid crystalline polyester, vacuum drying was performed at 160°C for 12 hours, and then the liquid crystalline polyester was stretched to a draw ratio of 3.5 using a tenter manufactured by Osaka Seimitsu Kogyosha Co., Ltd. A single screw extruder was used for melt extrusion, a gear pump was used for metering, and the polymer was supplied to a spinning pack. In the spinning pack, a metal nonwoven filter was used to filter the polymer, and the polymer was ejected under the conditions described in Table 2. Note that the introduction hole located directly above the spinneret was a straight hole, and the connection portion of the introduction hole to the spinneret was tapered. After the ejected polymer passed through a 40 mm heat retaining zone, it was cooled and solidified by a circular cooling air stream of 25°C from the outside of the yarn, and then a spinning oil containing a fatty acid ester compound as a main component was applied, and all the filaments were drawn to the first godet at the spinning speeds described in Table 2. After passing through the second godet at the same speed, the filaments other than one of all the filaments were sucked by a suction gun, and the remaining filament number 1 fiber passed through a dancer arm, and was wound into a pirn shape by a pirn winder (EFT type take up winder manufactured by KANZAKI MFG. CO., LTD., without a contact roller that contacts the wound package).

[0270] [Table 2]

[0271] [Table 2]

[0272]

[0273] A SSP-MV type rewinder (contact length: 200 mm, winding number: 8.7, taper angle: 45°) manufactured by KANZAKI MFG. CO., LTD. was used to rewind the spun fiber package. The drawing of the spun fiber was performed in the longitudinal direction (direction perpendicular to the fiber winding direction), and an oiling roller (stainless steel roller with pear skin finish) was used to apply the solid phase polymerization oil without using a speed regulating roller. Regarding the solid phase polymerization oil, 1.0% by weight of talc SG-2000 (manufactured by NIPPON TALC CO., LTD.) was dispersed in an aqueous solution containing 6.0% by weight of a phosphoric acid-based compound represented by the following formula (1).

[0274] [Chemical Formula 12]

[0275]

[0276] Regarding the core material of the rewound package, a core material having a Kevlar felt (unit area weight: 280 g / m 2 ; thickness: 1.5 mm) wound around a stainless steel open-end bobbin was used, and the face pressure was set to 100 gf. The oil partitioning attachment rate of the solid phase polymerization oil to the fiber after rewinding, and the rewinding conditions are shown in Table 3.

[0277] Next, the open-end tube made of stainless steel was taken out from the re-wound package in a state where the fiber was wound on the Kevlar felt, and solid phase polymerization was performed. As for the solid phase polymerization, a closed oven was used, and the temperature was raised from room temperature to 240°C in about 30 minutes, and kept at 240°C for 3 hours, and then, the temperature was raised at 4°C / hour to the maximum temperature shown in Table 3, and kept for the holding time shown in Table 3, and the solid phase polymerization was performed. Note that, as for the atmosphere, dehydrated nitrogen was supplied at a flow rate of 20 NL / minute, and exhaust was performed from the exhaust port so that the inside of the oven was not excessively pressurized.

[0278] [Table 3]

[0279] [Table 3]

[0280]

[0281] Next, the fiber was unwound from the package after the solid phase polymerization, and high-temperature non-contact heat treatment was continuously performed. The package after the solid phase polymerization was mounted on a free roller creel (having a shaft and a bearing, and the outer layer portion is freely rotatable. There is no brake and driving source.), and the yarn was pulled out from there along the lateral direction (fiber winding direction), and the fiber was continuously passed through a bath tank (having no guide member inside which comes into contact with the fiber) having a bath length of 150 cm (contact length of 150 cm) provided with slits at both ends, and the oil agent was washed away. As for the washing liquid, warm water at 50°C containing 0.2 wt% of a nonionic-anionic surfactant (Gran Up US-30 manufactured by Sanyo Chemical Industries, Ltd.) was prepared, the temperature was adjusted using an external tank, and the water tank was supplied using a pump. At the time of supply to the water tank, a pipe body perforated at intervals of 5 cm was inserted into the water tank, and by supplying water to the pipe body, a flow was imparted to the water tank. Note that, a mechanism for recovering the washing liquid overflowing from the slits and the liquid level adjustment hole and returning it to the external tank was provided.

[0282] Next, the washed fiber was passed through a bath tank (having no guide member inside which comes into contact with the fiber) having a bath length of 23 cm (contact length of 23 cm) provided with slits at both ends, and washing was performed using warm water at 50°C. The washed fiber was guided by a bearing roller guide, and was brought into contact with an air flow, and after the water was blown away, it was passed through a first roller provided with a separation roller. Note that, the creel was a free roller, and therefore, the fiber was imparted with tension by the roller, and thereby, unwinding from the solid phase polymerization package was performed, and the fiber was made to travel.

[0283] The fiber passing through the roll was made to travel between the heated slit heater, and high-temperature noncontact heat treatment was performed under the conditions shown in Table 4. No guide was provided in the slit heater, and the heater was also made noncontact with the fiber. The fiber after passing through the heater was made to pass through a second roll with a separation roll. Note that the yarn speed before heat treatment indicates the surface speed of the first roll, and the yarn speed after heat treatment indicates the surface speed of the second roll. The fiber after passing through the second roll was given a finishing oil agent with a fatty acid ester compound as the main component using an oiling roll made of ceramic, and was wound into a filament shape using an EFT-type bobbin traverse winder (manufactured by JIMTOU Corp.).

[0284] [Table 4]

[0285]

[0286] Using the obtained liquid crystalline polyester fiber, warping for warp was performed, and weaving was performed using an air-jet loom so that the mesh count would be 330 meshes / inch, to obtain mesh fabric A. The properties of this mesh fabric are shown in Table 5.

[0287] [Table 5]

[0288]

[0289] [Manufacturing Examples 2 to 3] Production of Mesh Fabric Containing Liquid Crystalline Polyester Fiber

[0290] Using the liquid crystalline polyester fiber obtained in Manufacturing Example 1, weaving was performed so that the mesh count would be 150 meshes / inch, and weaving was performed in the same manner as in Manufacturing Example 1 except for this, to obtain mesh fabric D of Manufacturing Example 2. The properties of this mesh fabric are shown in Table 5.

[0291] In addition, using the liquid crystalline polyester obtained in Manufacturing Example 1, spinning was performed in the same manner as in Manufacturing Example 1 except that the spinning conditions were set to the conditions shown in Table 2, the rewinding conditions were set to the conditions shown in Table 3, and the high-temperature heat treatment conditions were set to the conditions shown in Table 4, to obtain a liquid crystalline polyester fiber. Using this fiber, weaving was performed so that the mesh count would be 380 meshes / inch, and weaving was performed in the same manner as in Manufacturing Example 1 except for this, to obtain mesh fabric E of Manufacturing Example 3. The properties of this mesh fabric are shown in Table 5.

[0292] [Manufacturing Example 4] Production of Mesh Fabric Containing Polyphenylene Sulfide

[0293] Using a polyphenylene sulfide polymer having a melting point (Tml) of 278°C, a melt spinning machine having a single screw extruder was used, the spinning temperature was set to 330°C, and melt extrusion was performed at a single hole discharge amount = 2.6 g / min, and an unstretched yarn (single filament) was drawn at a draw speed of 850 m / min. The unstretched yarn was stretched using a hot roll type stretching machine at a draw ratio of 3.4 and a stretching temperature of 98°C, and heat set at 150°C to obtain a polyphenylene sulfide fiber having a fineness of 8.8 dtex. The fiber was woven so that the mesh count was 150 meshes / inch, and otherwise, the same operation as in Production Example 1 was performed to obtain a mesh fabric F. The tensile strength of the mesh fabric was 79 N / 5 cm.

[0294] [Example 1]

[0295] The 20 g of the block copolymer bl obtained in Synthesis Example 1 was dissolved in 80 g of NMP, and stirred at 20,000 rpm for 1 hour using a stirrer, and adjusted to a transparent polymer electrolyte solution bl having a polymer concentration of 20 mass%.

[0296] After the obtained polymer electrolyte solution bl was pressure-filtered using a glass fiber filter, the polymer electrolyte solution bl was cast-coated onto a PET substrate using an applicator so as to be attached to the mesh fabric A containing the liquid crystalline polyester fiber. After the polymer electrolyte solution bl was sufficiently impregnated by keeping at room temperature for 10 minutes, it was dried at 100°C for 4 hours. The polymer electrolyte solution bl was again cast-coated on the upper surface of the dried film, and after keeping at room temperature for 1 hour, it was dried at 100°C for 4 hours to obtain a film-shaped polymer. After the proton exchange and deprotection reaction were performed by immersing the film in 10 mass% sulfuric acid aqueous solution at 80°C for 24 hours, the film was sufficiently washed by immersing in a large amount of pure water for 24 hours to obtain a composite electrolyte film (film thickness: 50 μm).

[0297] [Example 2]

[0298] Instead of the polymer electrolyte solution bl, a 20% "Nafion (registered trademark)" solution (D2021) manufactured by Dupont was used, and otherwise, the same operation as in Example 1 was performed to obtain a composite electrolyte film (film thickness: 50 μm).

[0299] [Example 3]

[0300] Instead of the block copolymer bl, the block copolymer b2 obtained in Synthesis Example 2 was used, and otherwise, the same operation as in Example 1 was performed to obtain a composite electrolyte film (film thickness: 50 μm).

[0301] [Example 4]

[0302] Using the block copolymer b3 obtained in Synthetic Example 3 in place of the block copolymer bl, otherwise, the same operation as in Example 1 was performed to obtain a composite electrolyte membrane (film thickness: 50 μm).

[0303] [Example 5]

[0304] Using the random copolymer rl obtained in Synthetic Example 4 in place of the block copolymer bl, otherwise, the same operation as in Example 1 was performed to obtain a composite electrolyte membrane (film thickness: 50 μm).

[0305] [Example 6]

[0306] Using "V-SCREEN V330" (mesh fabric B) manufactured by NBC Corporation as a core-sheath composite fiber of a liquid crystal polyester and other components in place of the mesh fabric A, otherwise, the same operation as in Example 1 was performed to obtain a composite electrolyte membrane (film thickness: 50 μm).

[0307] [Comparative Example 1]

[0308] Without attaching the mesh fabric A, without performing the second casting of the polymer electrolyte solution A and drying, otherwise, the same operation as in Example 1 was performed to obtain a polymer electrolyte membrane (film thickness: 50 μm).

[0309] [Comparative Example 2]

[0310] Using a mesh fabric (mesh fabric C) containing polyether ether ketone fibers in place of the mesh fabric A, otherwise, the same operation as in Example 1 was performed to obtain a composite electrolyte membrane (film thickness: 100 μm).

[0311] [Examples 7-8]

[0312] Using the mesh fabric D in place of the mesh fabric A in Example 7, using the mesh fabric E in place of the mesh fabric A in Example 8, otherwise, the same operation as in Example 1 was performed to obtain a composite electrolyte membrane (film thickness: 50 μm).

[0313] [Example 9]

[0314] Using the mesh fabric F in place of the mesh fabric A, otherwise, the same operation as in Example 1 was performed to obtain a composite electrolyte membrane (film thickness: 60 μm).

[0315] [Example 10]

[0316] The film thickness was set to 80 μm, otherwise, the same operation as in Example 1 was performed to obtain a composite electrolyte membrane.

[0317] The results of the constitution and physical properties of the polymer electrolyte membranes used in each of the examples and comparative examples, the hydrogen compression evaluation, and the water electrolysis evaluation are shown in Tables 6 and 7.

[0318] [Table 6]

[0319]

[0320] [Table 7]

[0321]

Claims

1. A composite electrolyte membrane, characterized by, which has a 1-layer composite layer in which a mesh fabric and a polymer electrolyte are compounded, the mesh fabric contains liquid crystalline polyester fibers or polyphenylene sulfide fibers, and satisfies (1) and (2) below, (1) yarn thickness / fiber diameter < 2.0, (2) opening / fiber diameter > 1.0, the units of the yarn thickness, the fiber diameter, and the opening are μm, the liquid crystalline polyester fibers contain a liquid crystalline polyester single component.

2. The composite electrolyte film according to claim 1, characterized by the polymer electrolyte has proton conductivity.

3. The composite electrolyte film according to claim 1 or 2, characterized by, the polyphenylene sulfide fibers are formed of a copolymer containing 70 mol% or more of a p-phenylene sulfide unit represented by the following structural formula (1), 4. The composite electrolyte film according to claim 1 or 2, characterized by, the liquid crystalline polyester fibers contain a wholly aromatic polyester.

5. The composite electrolyte film according to claim 1 or 2, characterized by, the fiber diameter of the fibers constituting the mesh fabric is 50 μm or less.

6. The composite electrolyte film according to claim 1 or 2, characterized by the opening of the mesh fabric is 30 μm or more.

7. The composite electrolyte film according to claim 1 or 2, characterized by, the opening area of the mesh fabric is 30% or more.

8. The composite electrolyte film according to claim 1 or 2, characterized by, The mesh fabric has a transmission volume of 10 cc / m 2 The above.

9. The composite electrolyte film according to claim 1 or 2, characterized by, the yarn thickness of the mesh fabric is 50 μm or less.

10. The composite electrolyte film according to claim 1 or 2, characterized by, the heat of fusion ΔHm1 of the mesh fabric is 6.0 J / g or less.

11. The composite electrolyte film according to claim 1 or 2, characterized by, the polymer electrolyte is a hydrocarbon-based polymer electrolyte.

12. An electrolyte membrane with a catalyst layer, characterized by which has a catalyst layer on both sides of the composite electrolyte membrane described in any one of claims 1 to 11.

13. A membrane electrode composite, characterized by which contains the composite electrolyte membrane described in any one of claims 1 to 11.

14. An electrochemical hydrogen pump, characterized by which is made using the composite electrolyte membrane described in any one of claims 1 to 11.

15. A water electrolysis device, characterized by which is made using the composite electrolyte membrane described in any one of claims 1 to 11.

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