Electrolyte membrane, electrolyte membrane with catalyst layer, transfer sheet for producing same, membrane electrode assembly, water electrolytic device, and method for producing electrolyte

Abstract

The purpose of the present invention is to provide an electrolyte membrane having good adhesion between the electrolyte membrane and a catalyst layer. The main content is an electrolyte membrane comprising a layer (A) and a layer (B) on at least one surface of the layer (A), the porosity (X1) in the interface region of the layer (B) with the layer (A) being higher than the porosity (X2) in the interface region of the layer (B) on the opposite side from the layer (A).

Description

Technical Field

[0001] The present invention relates to an electrolyte membrane, an electrolyte membrane with a catalyst layer, a transfer sheet used for producing the same, a membrane electrode assembly, a water electrolysis device, and a method for producing an electrolyte membrane with a catalyst layer. Background Art

[0002] In recent years, hydrogen energy has attracted attention as a next-generation energy storage and transportation method. By using hydrogen as fuel for fuel cells, it can be converted into electricity with theoretically higher energy efficiency than power generation using heat engines, and the emission of harmful substances is relatively small, so it can become a highly efficient clean energy source.

[0003] One way to produce hydrogen is through the electrolysis of water. If water is electrolyzed using surplus electricity generated by renewable energy, electricity can be converted into hydrogen energy without emitting carbon dioxide. In addition, depending on the storage method, hydrogen can be transported by tank trucks or tankers and can be provided to necessary places when necessary, so water electrolysis has a high potential as a tool for electricity storage.

[0004] There are two ways to produce hydrogen by water electrolysis: alkaline water electrolysis and solid polymer electrolyte membrane (PEM) water electrolysis. PEM water electrolysis has the advantage of being able to operate at a high current density and flexibly respond to changes in the output of renewable energy.

[0005] PEM type water electrolysis device is usually composed of a single cell in which a membrane electrode assembly (Membrane Electrode Assembly: MEA) is sandwiched by a partition. MEA is composed of an electrolyte membrane with a catalyst layer (Catalyst Coated Membrane: CCM) with a catalyst layer formed on both sides of the polymer electrolyte membrane, one side of the catalyst layer is the anode catalyst layer, and the other side is the cathode catalyst layer. Water is supplied to the anode catalyst layer of the PEM type water electrolysis unit to which current is applied, and protons are generated by electrochemical reaction. Then, the protons diffuse in the polymer electrolyte membrane from the anode electrode layer side to the cathode electrode layer side, and hydrogen is generated from the protons by electrochemical reaction in the cathode layer.

[0006] In a PEM type water electrolysis device, the bonding property at the interface between the catalyst layer and the polymer electrolyte membrane may be reduced during water electrolysis operation.

[0007] Therefore, in order to improve the bonding property between the polymer electrolyte membrane and the catalyst layer, it has been proposed to dispose an adhesive layer between the polymer electrolyte membrane and the catalyst layer (for example, refer to Patent Documents 1 and 2).

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application No. 2008-512844

[0011] Patent Document 2: Japanese Patent Application Publication No. 2011-187436 Summary of the invention

[0012] Inventions should solve problems

[0013] However, the prior art disclosed in the above patent document cannot sufficiently improve the bonding between the polymer electrolyte membrane and the catalyst layer. If the bonding between the polymer electrolyte membrane and the catalyst layer is insufficient, for example, the polymer electrolyte membrane and the catalyst layer may be peeled off during operation of the water electrolysis device, thereby reducing durability.

[0014] In view of the above background, an object of the present invention is to provide an electrolyte membrane having good bonding properties with a catalyst layer.

[0015] Means of solving problems

[0016] In order to achieve the above-mentioned object, the electrolyte membrane of the present invention adopts the following structure. That is, the electrolyte membrane comprises an (A) layer containing a polymer electrolyte and a (B) layer located on at least one side of the (A) layer, wherein the porosity (X1) of the (B) layer in the interface region with the (A) layer is higher than the porosity (X2) of the (B) layer in the interface region on the side opposite to the (A) layer.

[0017] Effects of the Invention

[0018] According to the present invention, it is possible to provide an electrolyte membrane having excellent bonding properties between an electrolyte membrane and a catalyst layer and good durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic cross-sectional view of an electrolyte membrane according to Embodiment 1 of the present invention.

[0020] Figure 2 It is a schematic cross-sectional view of an electrolyte membrane with a catalyst layer formed by using the electrolyte membrane according to the first embodiment of the present invention.

[0021] Figure 3 It is a schematic cross-sectional view of an electrolyte membrane according to Embodiment 2 of the present invention.

[0022] Figure 4 It is a schematic cross-sectional view of an electrolyte membrane with a catalyst layer formed by using the electrolyte membrane according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0023] Hereinafter, the embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments and can be implemented after various changes according to the purpose and use. In addition, the description of the specific embodiments shown in the accompanying drawings can also be understood as the description of the present invention of the general concept.

[0024] The electrolyte membrane of an embodiment of the present invention is an electrolyte membrane comprising an (A) layer containing a polymer electrolyte and a (B) layer located on at least one side of the (A) layer. It is important that the porosity (X1) in the interface region between the (B) layer and the (A) layer is higher than the porosity (X2) in the interface region of the (B) layer on the side opposite to the (A) layer.

[0025] In the present invention, the interface region refers to a region in the (B) layer whose thickness is 10% of the thickness of the (B) layer as a whole from each interface between the (B) layer and other adjacent layers. The porosity (X1) and the porosity (X2) can be measured by observing the cross section of the electrolyte membrane with a field emission scanning electron microscope and performing image processing. The details are described in the examples.

[0026] (Implementation Method 1)

[0027] Figure 1 It is a schematic cross-sectional view showing an example of the electrolyte membrane according to the first embodiment of the present invention.

[0028] In the first embodiment, the electrolyte membrane 1 has a structure in which a (B) layer 20 is stacked on one surface of a (A) layer 10. The (B) layer 20 has an interface region 21 on the (A) layer side and an interface region 22 on the side opposite to the (A) layer. The porosity of the interface region 21 is porosity (X1), and the porosity of the interface region 22 is porosity (X2).

[0029] in addition, Figure 2 1 is a cross-sectional schematic diagram showing an example of an electrolyte membrane with a catalyst layer in which catalyst layers are stacked on both sides of the electrolyte membrane of Embodiment 1. Hereinafter, the electrolyte membrane with a catalyst layer (Catalyst Coated Membrane) is sometimes referred to as "CCM". CCM100 is a structure in which catalyst layers 30 and catalyst layers 40 are stacked on both sides of the electrolyte membrane 1. Here, the catalyst layers 30 and 40 are respectively an anode catalyst layer and a cathode catalyst layer in different orders.

[0030] The electrolyte membrane of the first embodiment is characterized in that the porosity (X1) of the interface region 21 between the (B) layer 20 and the (A) layer 10 is higher than the porosity (X2) of the interface region 22 of the (B) layer 20 on the side opposite to the (A) layer 10. As a result, the bonding between the electrolyte membrane 1 and the catalyst layer 30 is improved. Although the mechanism is not clear, it is speculated as follows.

[0031] Generally speaking, the degree of porosity of the outermost layer affects the surface roughness (concavity), and has the following tendency: when the porosity is high, the surface roughness (concavity) becomes larger, and when the porosity is low, the surface roughness (concavity) becomes smaller (smoothness becomes higher). In addition, it can be considered that the concavity formed on the outermost surface of the layer plays an anchoring role on the bonding interface with other layers.

[0032] Typically, the (A) layer 10 containing a polymer electrolyte has a relatively smooth surface, and the catalyst layers 30 and 40 have a concave-convex surface due to the presence of catalyst particles. Therefore, on the side of the (A) layer 10 having a smooth surface, the interface region 21 (porosity (X1) of the (B) layer 20 having a relatively high porosity is made to face it, and on the side of the catalyst layer 30 having a concave-convex surface, the interface region 22 (porosity (X2) of the (B) layer 20 having a relatively low porosity is made to face it, thereby showing an anchoring effect on the two interfaces. In this way, it can be considered that the bonding between the (A) layer 10 and the (B) layer 20 and the bonding between the (B) layer 20 and the catalyst layer 30 are respectively improved.

[0033] The present invention is particularly effective when the polymer electrolyte contained in the (A) layer 10 and the polymer electrolyte contained in the catalyst layer 30 are different from each other. This is because when the (A) layer 10 and the catalyst layer 30 contain polymer electrolytes of different types, interlayer bonding tends to decrease.

[0034] Here, the so-called polymer electrolytes are different in type, for example, one is a hydrocarbon polymer electrolyte and the other is a fluorine polymer electrolyte. Specifically, the case where the (A) layer 10 contains a hydrocarbon polymer electrolyte and the catalyst layer 30 contains a fluorine polymer electrolyte (form 1), the case where the (A) layer 10 contains a fluorine polymer electrolyte and the catalyst layer 30 contains a hydrocarbon polymer electrolyte (form 2), etc. can be cited. From the viewpoint of water electrolysis performance, form 1 is preferred.

[0035] As in the above-mentioned forms 1 and 2, when the polymer electrolyte contained in the (A) layer 10 and the polymer electrolyte contained in the catalyst layer 30 are of different types, from the viewpoint of bonding, the (B) layer 20 preferably contains a polymer of the same type as the catalyst layer 30. Here, the so-called same polymer type refers to the case where the main skeleton of the polymer is of the same type system regardless of the difference in ionicity or non-ionicity, fluorine-based polymers, hydrocarbon-based polymers, etc. For example, ionic fluorine-based polymers (fluorine-based polymer electrolytes) and non-ionic fluorine-based polymers are polymers of the same type, and similarly, ionic hydrocarbon-based polymers (hydrocarbon-based polymer electrolytes) and non-ionic hydrocarbon-based polymers are polymers of the same type. From the viewpoint of proton conductivity, the (B) layer 20 more preferably contains a polymer electrolyte of the same type as the polymer electrolyte contained in the catalyst layer 30. The polymer contained in the (B) layer 20 will be described in detail later.

[0036] Particularly preferred combinations of materials contained in the (A) layer, the catalyst layer, and the (B) layer include a structure in which the (A) layer contains a hydrocarbon-based polymer electrolyte, the catalyst layer contains a fluorine-based polymer electrolyte, and the (B) layer contains a fluorine-based polymer.

[0037] From the viewpoint of improving the bonding between the electrolyte membrane 1 and the catalyst layer 30, the porosity ratio (X2 / X1) of the porosity (X1) to the porosity (X2) is preferably 0.90 or less, more preferably 0.80 or less, and particularly preferably 0.70 or less. The lower limit of (X2 / X1) is 0.00.

[0038] From the viewpoint of improving the bonding property between the (A) layer 10 and the (B) layer 20, the porosity (X1) is preferably 20% or more, more preferably 22% or more, and particularly preferably 25% or more. From the viewpoint of film forming property of the coating film, the porosity (X1) is preferably 60% or less, more preferably 50% or less, further preferably 40% or less, and particularly preferably 37% or less.

[0039] From the viewpoint of improving the bonding property between the (B) layer 20 and the catalyst layer 30, the porosity (X2) is preferably less than 20%, more preferably less than 19%. The lower limit is 0%.

[0040] Furthermore, it is more preferred that the porosity (X1) is 20% or more and the porosity (X2) is less than 20%. Furthermore, within the range of the porosity ratio (X2 / X1), it is more preferred that the porosity (X1) is 20% or more and the porosity (X2) is less than 20%.

[0041] The porosity (X2) is preferably adjusted according to the mass ratio (C / I) of the content (C) of the catalyst particles (including the particles carrying the catalyst) contained in the catalyst layer 30 to the content (I) of the polymer electrolyte. Generally, the surface roughness (concavity and convexity) of the catalyst layer with a high C / I tends to become larger, and the surface roughness (concavity and convexity) of the catalyst layer with a low C / I tends to become smaller. In order to improve the anchoring effect of the bonding surface, (X2) is preferably lower relative to the catalyst layer with a relatively high C / I, and (X2) is preferably higher relative to the catalyst layer with a relatively low C / I. For example, when the above-mentioned mass ratio (C / I) is 4.0 or more, the porosity (X2) is more preferably less than 12%, further preferably less than 8%, and particularly preferably less than 6%. On the other hand, when the above-mentioned mass ratio (C / I) is less than 4.0, the porosity (X2) is preferably less than 20%.

[0042] When the (B) layer 20 is disposed only on one side of the (A) layer 10, it can be disposed only on the anode catalyst layer side or only on the cathode catalyst layer side. When the electrolyte membrane of the present embodiment 1 is applied to a water electrolysis device, by disposing the (B) layer 20 on the anode catalyst layer side, in addition to improving the bonding property, the effect of suppressing the electrochemical oxidation degradation of the (A) layer can also be expected. In addition, by disposing the (B) layer 20 on the cathode catalyst layer side, in addition to improving the bonding property, it can also be expected to protect the (A) layer from the influence of the peroxide radicals generated at the cathode byproduct.

[0043] In the water electrolysis device, the anode is in a high potential environment. In order to suppress the electrochemical oxidation degradation of the (A) layer 10, the (B) layer on the anode catalyst layer side preferably has a barrier function. From this point of view, when the catalyst layer 30 is the anode catalyst layer, the porosity (X2) of the (B) layer 20 on the anode catalyst layer side is preferably relatively low. Specifically, the porosity (X2) is preferably less than 12%, more preferably less than 8%, further preferably less than 6%, and most preferably 0%.

[0044] On the other hand, from the viewpoint of suppressing the interface peeling between the catalyst layer and the (B) layer caused by the hydrogen generated by the cathode (ensuring the escape channel of the hydrogen), when the catalyst layer 30 is the cathode catalyst layer, the porosity (X2) of the (B) layer 20 on the cathode catalyst layer side is preferably high. Specifically, the porosity (X2) is more preferably 3% or more, further preferably 5% or more, and particularly preferably 7% or more. In addition, the upper limit of the porosity (X2) is preferably less than 20%.

[0045] In addition, in the water electrolysis device, the ratio of the catalyst particles in the anode catalyst layer to the polymer electrolyte is set relatively large, so it is difficult to obtain the bonding between the anode catalyst layer and the (A) layer. Therefore, from the viewpoint of improving bonding, it is more beneficial to configure the (B) layer on the anode catalyst layer side. Therefore, it is more preferable that the catalyst layer 30 is the anode catalyst layer.

[0046] (Implementation Method 2)

[0047] Figure 3 1 is a schematic cross-sectional view showing an example of an electrolyte membrane according to Embodiment 2 of the present invention. In Embodiment 2, the electrolyte membrane 2 has a structure in which a (B) layer 20a is stacked on one surface of a (A) layer 10 and another (B) layer 20b is stacked on the opposite surface.

[0048] The (B) layer 20a has an interface region 21a on the (A) layer 10 side and an interface region 22a on the side opposite to the (A) layer 10. The (B) layer 20b has an interface region 21b on the (A) layer 10 side and an interface region 22b on the side opposite to the (A) layer 10.

[0049] The porosity of the interface regions 21a and 21b is porosity (X1), and the porosity of the interface regions 22a and 22b is porosity (X2). Here, for the sake of distinction, if the porosities in the interface regions 21a and 21b are respectively set to (X1-1) and (X1-2), and the porosities in the interface regions 22a and 22b are respectively set to (X2-1) and (X2-2), then (X1-1) and (X1-2) may be the same or different, and (X2-1) and (X2-2) may be the same or different. In this case, the porosity (X1) being higher than the porosity (X2) means that (X1-1)>(X2-1) and / or (X1-2)>(X2-2).

[0050] in addition, Figure 4 The schematic cross-sectional view shows an example of an electrolyte membrane (CCM) with a catalyst layer, in which an anode catalyst layer 50 is stacked on the (B) layer 20a side of the electrolyte membrane of Embodiment 2 and a cathode catalyst layer 60 is stacked on the (B) layer 20b side. The CCM 200 has a structure in which the anode catalyst layer 50 and the cathode catalyst layer 60 are stacked on both sides of the electrolyte membrane 2.

[0051] In CCM 200, the relationship of (X1)>(X2) is preferably satisfied at least in the (B) layer 20a on the anode catalyst layer 50 side, and more preferably satisfied in both the (B) layer 20a on the anode catalyst layer 50 side and the (B) layer 20b on the cathode catalyst layer 60 side. That is, preferably (X1-1)>(X2-1), more preferably (X1-1)>(X2-1) and (X1-2)>(X2-2).

[0052] The porosity (X2-1) in the (B) layer 20a on the anode catalyst layer 50 side is preferably smaller than the porosity (X2-2) in the (B) layer 20b on the cathode catalyst layer 60 side. In addition, it is particularly preferred that the porosity (X2-1) in the (B) layer 20a adjacent to the anode catalyst layer 50 is less than 12%, and the porosity (X2-2) in the (B) layer 20b adjacent to the cathode catalyst layer 60 is less than 20%.

[0053] Hereinafter, matters common to the respective embodiments included in the present invention will be described in detail.

[0054] [(A) layer]

[0055] The (A) layer contains a polymer electrolyte. Examples of the polymer electrolyte include fluorine-based polymer electrolytes and hydrocarbon-based polymer electrolytes. From the viewpoint of water electrolysis performance, hydrocarbon-based polymer electrolytes are preferred.

[0056] Here, fluorine-based polymer electrolyte refers to a fluorine-based polymer having an ionic group. Fluorine-based polymer refers to a polymer in which most or all hydrogen atoms of an alkyl group and / or an alkylene group in the polymer are replaced by fluorine atoms. As representative examples of fluorine-based polymer electrolytes, commercial products such as Nafion (registered trademark) (manufactured by DuPont), Fluemion (registered trademark) (manufactured by Asahi Glass Co., Ltd.) and Aspyrex (registered trademark) (manufactured by Asahi Kasei Corporation) can be cited.

[0057] Hydrocarbon-based polymer electrolytes refer to hydrocarbon-based polymers having ionic groups. As hydrocarbon-based polymers, aromatic hydrocarbon-based polymers having aromatic rings in the main chain are preferred. Here, the aromatic rings may include not only hydrocarbon-based aromatic rings but also heterocyclic rings. In addition, a portion of aliphatic units may also constitute the polymer together with the aromatic ring units.

[0058] As specific examples of aromatic hydrocarbon polymers, there can be listed polymers having structures selected from polysulfone, polyethersulfone, polyphenylene ether, polyarylether polymers, polyphenylene sulfide, polyphenylene sulfide sulfone, polyparaphenylene, polyarylene polymers, polyaryl ketone, polyetherketone, polyarylphosphine oxide, polyetherphosphine oxide, polybenzoxazole, polybenzothiazole, polybenzimidazole, polyamide, polyimide, polyetherimide, and polyimide sulfone together with aromatic rings on the main chain. In addition, the polysulfone, polyethersulfone, polyetherketone, etc. mentioned here are general terms for structures having sulfone bonds, ether bonds, and ketone bonds on their molecular chains, including polyetherketoneketone, polyetheretherketone, polyetheretherketoneketone, polyetherketoneetherketoneketone, polyetherketonesulfone, etc. The hydrocarbon skeleton can have multiple structures among these structures. Among them, as aromatic hydrocarbon polymers, polymers having polyetherketone skeletons, i.e., polyetherketone polymers, are most preferably used.

[0059] As a hydrocarbon-based polymer electrolyte, it is preferred to have a block copolymer having one or more segments (A1) containing an ionic group and one or more segments (A2) not containing an ionic group. Here, the segment represents a partial structure having a molecular weight of 2000 or more in a copolymer polymer chain consisting of repeating units showing specific properties. By using a block copolymer, a co-continuous phase separation structure having finer phase domains than a polymer blend can be exhibited, and more excellent power generation performance and physical durability can be achieved.

[0060] Hereinafter, the segment (A1) or polymer containing an ionic group may be described as an "ionic block", and the segment (A2) or polymer not containing an ionic group may be described as a "non-ionic block". In addition, the description of "not containing an ionic group" does not exclude the form in which the segment or polymer contains a small amount of ionic groups within a range that does not hinder the effect of the present invention.

[0061] The ionic group possessed by the polymer electrolyte can be any ionic group having proton exchange capacity. As such a functional group, it is preferred to use a functional group selected from a sulfonic acid group, a sulfonimide group, a sulfate group, a phosphonic acid group, a phosphoric acid group and a carboxylic acid group. The ionic group may include two or more in the polymer. Among them, from the viewpoint of high proton conductivity, the polymer more preferably has at least one selected from a sulfonic acid group, a sulfonimide group and a sulfate group, and from the viewpoint of raw material cost, it is most preferred to have a sulfonic acid group.

[0062] From the perspective of the balance between proton conductivity and water resistance, the ion exchange capacity (IEC) of the polymer electrolyte is preferably 0.1 meq / g or more and 5.0 meq / g or less. The IEC is more preferably 1.4 meq / g or more, and further preferably 2.0 meq / g or more. In addition, the IEC is more preferably 3.5 meq / g or less, and further preferably 3.0 meq / g or less. When the IEC is less than 0.1 meq / g, the proton conductivity may be insufficient, and when the IEC is greater than 5.0 meq / g, the water resistance may be insufficient.

[0063] Here, IEC is the molar amount of the ionic groups introduced per unit dry weight of the polymer electrolyte, and the larger the value, the more the amount of ionic groups introduced. In the present invention, IEC is defined as the value obtained by neutralization titration. IEC is calculated by neutralization titration according to the method described in Example 2.

[0064] In the present invention, as the hydrocarbon-based polymer electrolyte, an aromatic hydrocarbon-based block copolymer is particularly preferably used, and a polyetherketone-based block copolymer is more preferably used. The following polyetherketone-based block copolymer is particularly preferably used, and the polyetherketone-based block copolymer contains: a segment having the following structural unit (S1) containing an ionic group, and a segment having a structural unit (S2) not containing an ionic group.

[0065]

[0066] In the general formula (S1), Ar 1 ~Ar 4 represents any divalent arylene group, Ar 1 and / or Ar 2 Contains ionic groups, Ar 3 and Ar 4 It may or may not contain an ionic group. 1 ~Ar 4 The arylene group may be arbitrarily substituted, and two or more arylene groups may be used independently of each other. * represents a bonding site with the general formula (S1) or other structural units.

[0067]

[0068] In the general formula (S2), Ar 5 ~Ar 8 represents an arbitrary divalent arylene group, which may be arbitrarily substituted but does not contain an ionic group. 5 ~Ar 8 Two or more arylene groups may be used independently of each other. * represents a bonding site with the general formula (S2) or other structural units.

[0069] Here, as Ar 1 ~Ar 8 Preferred divalent arylene groups include hydrocarbon arylene groups such as phenylene, naphthylene, biphenylene, and fluorenediyl, and heteroarylene groups such as pyridinediyl, quinoxalinediyl, and thiophenediyl, but are not limited thereto. Here, as "phenylene", there can be three types, namely, o-phenylene, m-phenylene, and p-phenylene, depending on the position of the bonding site with the benzene ring and other constituent units, but in the case of no particular limitation in this specification, they are used as a general term. The same applies to other divalent arylene groups such as "naphthylene" or "biphenylene". Ar 1 ~Ar 8 Preferably, it is a phenylene group containing a phenylene group and an ionic group, and most preferably, it is a p-phenylene group containing a p-phenylene group and an ionic group. 5 ~Ar 8 It may be substituted with a group other than an ionic group, but is more preferably unsubstituted from the viewpoint of proton conductivity, chemical stability, and physical durability.

[0070] In addition, in order to obtain sufficient dimensional stability, mechanical strength, physical durability, fuel barrier properties, and solvent resistance, the polymer electrolyte is preferably a crystalline aromatic hydrocarbon polymer. Here, "crystalline" means having a crystallizable property that can crystallize when heated, or has already crystallized.

[0071] Whether there is a crystallizable property that can crystallize when the temperature is increased can be confirmed by confirming that the heat of crystallization measured by differential scanning calorimetry (DSC) after film formation is 0.1 J / g or more. Already crystallized can be confirmed by a degree of crystallinity measured by wide-angle X-ray diffraction of 0.5% or more. That is, in the present invention, it is preferred that the heat of crystallization measured by differential scanning calorimetry (DSC) after film formation is 0.1 J / g or more, or the degree of crystallinity measured by wide-angle X-ray diffraction is 0.5% or more.

[0072] Aromatic hydrocarbon polymers with crystallinity sometimes have poor processability of electrolyte membranes. In this case, a protecting group may be introduced into the aromatic hydrocarbon polymer to temporarily suppress crystallinity. Specifically, by forming a membrane with a protecting group introduced and then deprotecting it, a crystalline aromatic hydrocarbon polymer can be used as a polymer electrolyte in the present invention.

[0073] (A) layer can be enhanced with a porous substrate. As the form of the porous substrate, woven fabric, nonwoven fabric, porous membrane, mesh fabric, etc. can be listed. As the material of the porous substrate, known materials such as hydrocarbon-based porous substrates or fluorine-based porous substrates can be used.

[0074] The layer (A) may contain various additives such as a surfactant, a radical scavenger, a hydrogen peroxide decomposer, a non-electrolyte polymer, an elastomer, a filler, etc., within a range not inhibiting the effects of the present invention.

[0075] When the electrolyte membrane of the present invention is applied to a water electrolysis device, the thickness of the (A) layer is preferably relatively large, specifically, preferably 30 μm or more, more preferably 50 μm or more, particularly preferably 70 μm or more, and preferably 250 μm or less, more preferably 200 μm or less, particularly preferably 175 μm or less.

[0076] [(B) Layer]

[0077] The (B) layer has the function of improving the bonding between the (A) layer and the catalyst layer, that is, the function of a bonding layer. The (B) layer has an interface region with the (A) layer and an interface region on the side opposite to the (A) layer, and the porosity in these two interface regions is different. Such a (B) layer can be composed of a single layer or a stack of two or more layers.

[0078] The pores in the interface region can be formed, for example, by containing particles. Moreover, the porosity can be controlled, for example, by adjusting the particle density. From the viewpoint of adjusting the particle density and controlling the porosity, the (B) layer preferably contains at least particles and a polymer. That is, the porosity can be controlled by adjusting the ratio (P / F) between the mass (P) of the polymer and the mass (F) of the particles. Generally, when the ratio (P / F) increases, the porosity decreases.

[0079] When the (B) layer is a single layer, for example, in the process of applying a coating liquid containing particles and polymers on the horizontally mounted or horizontally transported (A) layer and drying, the porosity (X1) can be increased relative to the porosity (X2) by implementing an operation to increase the particle density on the (A) layer side. As the above-mentioned operation, for example, a method of using particles with a specific gravity sufficiently larger than that of the polymer to make the coating liquid viscosity relatively low, slowing down the drying speed, thereby making it easy for the particles to settle, or a method of separating the particles from the polymer, etc. As the above-mentioned phase separation method, for example, a method of using particles and polymers having a surface tension sufficiently lower than that of the particles and being incompatible with the particles, and a solvent having a relatively high compatibility with the particles, thereby making it easy for the polymer to be biased toward the air interface during phase separation during drying, etc. can be listed.

[0080] (B) layer preferably has a laminated structure. By making (B) layer a laminated structure, porosity (X1) and porosity (X2) can be easily controlled. For example, by applying multiple coating solutions with different ratios (P / F) of polymer and particles on (A) layer, a (B) layer of a laminated structure with different porosity according to the layer is formed. Thus, even if the porosity in each layer is uniform, a (B) layer with a porosity (X1) higher than the porosity (X2) can be obtained.

[0081] When the (B) layer is a stacked structure consisting of n layers, they are referred to as (B-1) layer, (B-2) layer, ... (Bn) layer in order from the (A) layer side. When the (B) layer is a stacked structure, the (B-1) layer adjacent to the (A) layer preferably has the highest porosity.

[0082] When the (B) layer is a laminated structure, it is preferably a 2-layer structure or a 3-layer structure, and more preferably a 2-layer structure. When the (B) layer is composed of 2 layers, the layer adjacent to the (A) layer is the (B-1) layer, and the layer on the side opposite to the (A) layer is the (B-2) layer. The following describes the morphology of the 2-layer structure, but the present invention is not limited thereto.

[0083] The (B-1) layer in the two-layer structure is a layer including the interface region with the (A) layer. That is, the (B-1) layer is a layer providing the porosity (X1) in the interface region with the (A) layer. The (B-2) layer is a layer including the interface region on the side opposite to the (A) layer. That is, the (B-2) layer is a layer providing the porosity (X2) in the interface region on the side opposite to the (A) layer.

[0084] In the (B-1) layer in the two-layer structure, for example, from the viewpoint of controlling the porosity (X1) to be 20% or more, the ratio (P / F) of the mass of the polymer (P) to the mass of the particles (F) is preferably in the range of 0.2 to 1.6, more preferably in the range of 0.4 to 1.4, and particularly preferably in the range of 0.6 to 1.2.

[0085] In the (B-2) layer in the two-layer structure, for example, from the viewpoint of controlling the porosity (X2) to less than 20%, the above ratio (P / F) is preferably 1.2 or more, more preferably 1.4 or more, and particularly preferably 1.6 or more. When the porosity (X2) contains 0%, it is preferred that the (B-2) layer has a structure that does not contain particles, that is, is composed only of polymer.

[0086] When the (B) layer is a two-layer structure, the (B-2) layer includes a form without particles as described above. Even if the (B-2) layer does not contain particles, when the (B-1) layer contains particles, it is equivalent to the case where "the (B) layer contains particles and polymers".

[0087] When the layer (B) contains particles, examples of the particles include inorganic particles, organic particles, and organic-inorganic composite particles.

[0088] Examples of the inorganic particles include carbon particles, silica, titanium oxide, aluminum oxide, zirconium oxide, cerium oxide, calcium carbonate, zeolite, mica, sericite, sericite, kaolin, mica, talc, and montmorillonite.

[0089] Among the above inorganic particles, carbon particles are preferred because they are relatively stable to acids and alkalis. Examples of the carbon particles include carbon black, graphite, activated carbon, carbon nanotubes, carbon nanofibers, and fullerene.

[0090] As organic particles, various resin particles can be listed. As resins constituting the resin particles, thermoplastic resins or thermosetting resins such as polyethylene resins, polypropylene resins, polyvinyl acetate resins, poly(meth)acrylic acid resins, polyvinyl chloride resins, polystyrene resins, polycarbonate resins, polyester resins, polyphenylene sulfide resins, polyamide resins, polyimide resins, polyurethane resins, ethylene-(meth)acrylate copolymers, ABS resins, fluorine resins, epoxy resins, phenolic resins, melamine resins, guanamine resins, polyazole resins, polyether sulfone resins, and polyether ketone resins can be listed.

[0091] Examples of the organic-inorganic composite particles include acrylic-silica composite particles, melamine-silica composite particles, benzoguanamine-silica composite particles, benzoguanamine-melamine-silica composite particles, polystyrene-silica composite particles, silsesquioxane-based organic-inorganic hybrid particles, and inorganic nanoparticles coated with organic matter.

[0092] Among the above particles, inorganic particles are preferred, carbon particles are more preferred, and carbon black is particularly preferred.

[0093] From the viewpoint of effective pore formation, dispersibility and film forming property for bonding, the average particle size of the particles is preferably 5 nm or more, more preferably 10 nm or more, and particularly preferably 20 nm or more. In addition, it is preferably 1000 nm or less, more preferably 500 nm or less, and particularly preferably 200 nm or less.

[0094] When the layer (B) contains a polymer, a nonionic polymer or an ionic polymer can be used as the polymer. These polymers can be used alone or in combination of two or more.

[0095] As the nonionic polymer, fluorine-based polymers or hydrocarbon-based polymers can be cited. As the nonionic fluorine-based polymer, polytetrafluoroethylene, poly(vinylidene fluoride), copolymers of vinylidene fluoride and hexafluoropropylene, copolymers of vinylidene fluoride and trifluoroethylene, copolymers of vinylidene fluoride and tetrafluoroethylene, poly(vinylidene fluoride), etc. can be cited.

[0096] Examples of the nonionic hydrocarbon polymer include polysulfone, polyethersulfone, polyphenylene ether, polyarylether, polyphenylene sulfide, polyphenylene sulfide, polyphenylene sulfide sulfone, polyparaphenylene, polyarylene polymers, polyarylene ketone, polyetherketone, polyarylphosphine oxide, polyetherphosphine oxide, polybenzoxazole, polybenzothiazole, polybenzimidazole, polyamide, polyimide, polyetherimide, polyimide sulfone, and polyvinyl alcohol.

[0097] Examples of the ionic polymer include ionic fluorine-based polymers and ionic hydrocarbon-based polymers. Examples of these polymers include the polymers listed as examples of the above-mentioned fluorine-based polymer electrolytes and hydrocarbon-based polymer electrolytes.

[0098] Among them, from the viewpoint of imparting a barrier function in a high potential environment to the (B) layer, a fluorine-based polymer is preferred, and from the viewpoint of improving proton conductivity, a hydrocarbon-based polymer electrolyte or a fluorine-based polymer electrolyte is preferred. That is, when the (B) layer contains a polymer, from the above viewpoint, a fluorine-based polymer electrolyte is most preferred.

[0099] When the (B) layer has a laminated structure, the particles and polymers contained in each layer may be of the same or different types, but are preferably of the same type from the viewpoint of bonding within the (B) layer.

[0100] The layer (B) may contain various additives such as a surfactant, a radical scavenger, a hydrogen peroxide decomposer, a non-electrolyte polymer, an elastomer, etc., within a range not inhibiting the effects of the present invention.

[0101] From the viewpoint of improving the bonding function, the thickness of the (B) layer is preferably 0.5 μm or more, more preferably 0.8 μm or more, and particularly preferably 1 μm or more. From the viewpoint of ensuring good proton conductivity, the thickness is preferably 20 μm or less, more preferably 15 μm or less, and particularly preferably 10 μm or less.

[0102] In particular, it is preferred that the thickness of the (A) layer is 30 μm to 250 μm, and the thickness of the (B) layer is 0.5 μm to 20 μm.

[0103] When the (B) layer is a laminated structure, the thickness of each layer constituting the (B) layer may be the same or different. For example, when the (B) layer is a two-layer structure, the thickness of the (B-1) layer is preferably in the range of 0.25 μm to 10 μm, more preferably in the range of 0.4 μm to 7.5 μm, and particularly preferably in the range of 0.5 μm to 5 μm. The thickness of the (B-2) layer is preferably in the range of 0.25 μm to 10 μm, more preferably in the range of 0.4 μm to 7.5 μm, and particularly preferably in the range of 0.5 μm to 5 μm. When the (B) layer is a two-layer structure, the thickness of the (B-1) layer and the (B-2) layer are each preferably more than 10% of the total thickness of the (B) layer. In addition, the thickness of the layer can be measured by a contact film thickness measurement method or SEM observation measurement described in the examples.

[0104] [Method for producing electrolyte membrane]

[0105] Hereinafter, a method for producing the electrolyte membrane will be described, but the present invention is not limited to these production methods.

[0106] First, the method for producing the (A) layer is described. The (A) layer can be formed into a film, for example, by coating or melt extrusion. Among them, the coating method is preferred. The coating method is used as an example for description below, but the present invention is not limited thereto.

[0107] The (A) layer can be produced, for example, by coating a polymer electrolyte solution on a film-forming substrate such as a polyethylene terephthalate (PET) film and drying the coating.

[0108] The (A) layer may be a so-called "composite membrane" reinforced with a porous substrate. The composite membrane preferably has a polymer electrolyte layer on one or both sides of a porous substrate impregnated with a polymer electrolyte. As a method for producing the composite membrane, for example, a porous substrate is attached to a polymer electrolyte solution coated on a film-forming substrate to impregnate it, and then a polymer electrolyte solution is coated on the porous substrate and dried.

[0109] In addition, as a polymer electrolyte, an electrolyte in which an ionic group forms a salt with a cation of an alkali metal or alkaline earth metal may also be used. In this case, it is preferred that an acid treatment for exchanging the cation of an alkali metal or alkaline earth metal with a proton is performed after the electrolyte membrane is formed on the film-forming substrate. The acid treatment may be performed by a known method.

[0110] The electrolyte membrane of the embodiment of the present invention is produced by laminating the (B) layer on the (A) layer produced as described above. The lamination method is not particularly limited, and a coating method, a transfer method, or a combination thereof can be used.

[0111] The coating method is a method of coating a coating liquid for the (B) layer on the (A) layer formed on the film-forming substrate, and laminating after drying. The transfer method is a method of transferring the (B) layer to the (A) layer by heating and pressing a transfer sheet having the (B) layer laminated on a transfer substrate and the (A) layer formed on the film-forming substrate.

[0112] When the (B) layer has a laminated structure, the coating liquid for the (B-1) layer may be applied onto the (A) layer formed on the film-forming substrate, and the coating liquid for the (B-2) layer may be applied before or after drying and then dried. Alternatively, two coating liquids having different polymer to particle ratios (P / F) may be prepared, and the two coating liquids may be simultaneously applied onto the (A) layer using a multilayer die or a multilayer slide coater and then dried.

[0113] As a transfer method, the (B) layer transfer sheet in which the (B-2) layer and the (B-1) layer are stacked in sequence on the transfer substrate and the (A) layer formed on the film-forming substrate are heated and pressed to transfer the (B-1) layer and the (B-2) layer to the (A) layer.

[0114] In the above-mentioned method, since the bonding property with the (A) layer is high and the interface resistance can be suppressed, the coating method is more preferred. The coating method is not particularly limited as long as it can be coated into a target shape, for example, die coating, screen printing, spray coating, gravure coating, slide coating, etc. can be used.

[0115] Regarding the method for manufacturing an electrolyte membrane in which a (B) layer is laminated on both sides of a (A) layer, the coating method, transfer method, and a combination of the coating method and the transfer method as described above may also be used. In addition, in the following manufacturing method, the (B) layer laminated on one side of the (A) layer is referred to as the first (B) layer, and the (B) layer laminated on the other side of the (A) layer is referred to as the second (B) layer.

[0116] As a production method using a coating method, for example, there can be mentioned a production method having the following steps: step (1-1) of coating a coating liquid for the first (B) layer on the (A) layer formed on the film-forming substrate and drying to laminate, step (1-2) of peeling off the film-forming substrate to expose the surface of the (A) layer opposite to the first (B) layer, and step (1-3) of coating a coating liquid for the second (B) layer on the exposed (A) layer and drying to laminate. Between the above steps (1-1) and (1-3), a step of laminating a protective substrate on the first (B) layer can be provided. As the protective substrate, a substrate that is the same as the film-forming substrate or the transfer substrate, or a substrate having a slightly adhesive layer laminated on a resin film can be used.

[0117] As a manufacturing method using a transfer method, there can be listed, for example, a manufacturing method having the following steps: a step (2-1) of respectively obtaining a 1st (B layer) transfer sheet having a 1st (B) layer stacked on a transfer substrate and a 2nd (B) layer transfer sheet having a 2nd (B) layer stacked on a transfer substrate, a step (2-2) of peeling off the film-forming substrate from the (A) layer formed on the film-forming substrate, and a step (2-3) of heating and pressing the (A) layer between the 1st (B) layer transfer sheet and the 2nd (B) layer transfer sheet.

[0118] As a manufacturing method using a coating method and a transfer method in combination, for example, there can be cited a manufacturing method having the following steps: a step (3-1) of coating a coating liquid for the first (B) layer on the (A) layer formed on the film-forming substrate, drying and laminating, a step (3-2) of obtaining a second (B) layer transfer sheet having the second (B) layer laminated on the transfer substrate, a step (3-3) of peeling the film-forming substrate from the (A) layer formed on the film-forming substrate to expose the surface of the (A) layer opposite to the first (B) layer, and a step (3-4) of bringing the exposed (A) layer into contact with the second (B) layer transfer sheet and heating and pressing. Between the above steps (3-1) and (3-4), a step of laminating a protective substrate on the first (B) layer can be provided.

[0119] As a modified example of the production method using the above-mentioned combined method, there is a production method in which the first (B) layer is laminated by transfer and the second (B) layer is laminated by coating.

[0120] In the above production method, either the first (B) layer or the second (B) layer may have a laminated structure of the (B-1) layer and the (B-2) layer, or both layers may have a laminated structure.

[0121] In the production process of CCM, a method of laminating the (B) layer together with the catalyst layer on the (A) layer may be adopted. The details will be described later.

[0122] The method for preparing the coating liquid for the (B) layer is not particularly limited as long as it is a method that can obtain the target coating liquid, and examples thereof include stirring with a stirrer, pulverizing with a homogenizer, homogenizing with a revolving mixer, and dispersing with a bead mill or a ball mill.

[0123] The solvent contained in the coating liquid for the (B) layer is not particularly limited as long as it can disperse the particles and the polymer, but is preferably a solvent that can be easily evaporated and removed by heating. For example, a solvent having a boiling point of 140° C. or less is preferred. As the solvent of the coating liquid for the (B) layer, specifically, alcohols such as water, methanol, ethanol, n-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, and pentanol; ketones such as acetone, methyl ethyl ketone, pentanone, hexanone, heptanone, cyclohexanone, methylcyclohexanone, acetylacetone, and diisobutyl ketone; ethers such as tetrahydrofuran, dioxane, diethylene glycol dimethyl ether, anisole, methoxytoluene, and dibutyl ether; esters such as methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, butyl acetate, methyl lactate, ethyl lactate, and butyl lactate; and dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, propylene glycol, diethylene glycol, diacetone alcohol, 1-methoxy-2-propanol, and the like, or a mixture of two or more thereof can be used.

[0124] After coating the coating solution for the (B) layer on the (A) layer, a drying process is performed as required to form the (B) layer. In the drying process, the coating is heated to evaporate the solvent. The heating means is not particularly limited as long as it can heat the fixed polymer electrolyte membrane. For example, a heating device such as an oven or a heater, a device for controlling the temperature near the polymer electrolyte membrane using infrared rays, warm air, etc., etc. can be used. In addition, heat can also be conducted to the polymer electrolyte membrane by a fixing mechanism. The preferred heating temperature range is close to the boiling point of the solvent and is below the glass transition temperature of the polymer electrolyte membrane. In addition, the solvent can be removed only by reducing pressure or introducing airflow without heating, and the drying process can also be omitted.

[0125] The (B) layer transfer sheet can be prepared by coating the (B) layer coating liquid on the transfer substrate and undergoing a drying process as needed. The drying process can use the above-mentioned method. Next, by overlapping the (B) layer coating surface of the (A) layer and the (B) layer transfer sheet and performing hot pressing, the (B) layer can be laminated on the (A) layer. The temperature and pressure of the hot press can be appropriately selected according to the thickness of the (A) layer, the moisture content, the thickness of the (B) layer and the type of transfer substrate, but from the viewpoints of industrial productivity and thermal decomposition suppression of the polymer electrolyte, it is preferably carried out in the range of 120°C to 250°C. Specifically, it is more preferably carried out at a temperature greater than the glass transition temperature of the polymer contained in the (B) layer and below 200°C. From the viewpoint of protecting the electrolyte membrane, the pressure in the hot pressing is preferably as weak as possible, for example, in the case of flat plate pressing, the range of 2 to 10 MPa is preferably preferred.

[0126] As transfer substrate, in addition to the resin film or substrate identical with the substrate used during (A) layer film making, the fluorine resin film composed of fluorine resins such as polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, ethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, polyvinylidene fluoride can also be used. In addition, transfer substrate can also be a substrate formed by laminating a release layer containing a known release agent such as a fluorine release agent on a substrate such as a resin film in order to improve release. As the transfer substrate used in the present invention, in addition to heat resistance and solvent resistance, from the viewpoint of chemical stability and release, preferably a fluorine resin film.

[0127] [Catalyst layer electrolyte membrane (CCM)]

[0128] The electrolyte membrane according to the embodiment of the present invention may be formed into a CCM by disposing a catalyst layer on one or both surfaces thereof. That is, the CCM includes a catalyst layer on one or both surfaces of the electrolyte membrane.

[0129] [Catalyst layer]

[0130] The catalyst layer is usually a layer comprising catalyst particles and a polymer electrolyte. The catalyst layer can be formed by laminating a catalyst layer coating liquid to which catalyst particles are added to a polymer electrolyte solution on an electrolyte membrane by coating or transfer. As the polymer electrolyte, a hydrocarbon polymer electrolyte or a fluorine polymer electrolyte as described above can be used. From the viewpoint of gas diffusivity and chemical durability, a fluorine polymer electrolyte is preferred, and a perfluorocarbon sulfonic acid polymer is further preferred.

[0131] As catalyst particles, platinum group elements (platinum, ruthenium, rhodium, palladium, osmium, iridium), iron, lead, gold, silver, copper, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum and other metals or their alloys, or oxides, composite oxides, etc. are generally used. In addition, carbon particles carrying the above metals (carbon particles carrying catalysts) are also generally used. As the above carbon particles, as long as they are particulate and have electrical conductivity, and are not corroded or deteriorated by reaction with the catalyst, there is no particular limitation, and preferably carbon black, graphite, activated carbon, carbon fiber, carbon nanotubes and fullerene particles are used.

[0132] The mass ratio (C / I) of the content (C) of catalyst particles (including catalyst-supporting particles) to the content (I) of the polymer electrolyte in the catalyst layer is generally in the range of 1.0 to 15.0, preferably in the range of 1.5 to 13.0.

[0133] When applied to a water electrolysis device, the mass ratio (C / I) in the anode catalyst layer is preferably 4.0 or more, more preferably 5.0 or more, and particularly preferably 7.0 or more. In addition, it is preferably 15.0 or less, more preferably 14.0 or less, and particularly preferably 13.0 or less. On the other hand, the mass ratio (C / I) in the cathode catalyst layer is preferably less than 4.0, more preferably less than 3.5, and particularly preferably less than 3.0. In addition, it is preferably 1.0 or more, more preferably 1.5 or more, and particularly preferably 1.7 or more.

[0134] From the viewpoint of gas diffusibility and durability, the thickness of the catalyst layer is preferably 0.1 μm or more, more preferably 0.5 μm or more, particularly preferably 1 μm or more, and preferably 500 μm or less, more preferably 100 μm or less, particularly preferably 30 μm or less.

[0135] The anode catalyst layer and the cathode catalyst layer can be composed of the same material or different materials. When CCM is applied to a water electrolysis device, the anode catalyst layer can be made of a catalyst that can generate oxygen with water or hydroxide as a raw material, preferably using noble metals such as iridium, ruthenium, rhodium, palladium or their oxides. At this time, the catalyst particles can be used in the form of individual particles, or can be used as particles of a supported catalyst supported on titanium oxide, etc. The cathode catalyst layer can be made of a catalyst that can generate hydrogen with protons or water as a raw material, preferably using carbon particles supported by platinum supported on carbon particles.

[0136] [Method for producing CCM]

[0137] The CCM according to an embodiment of the present invention is manufactured by stacking a catalyst layer on an electrolyte membrane. There is no particular limitation on the method for stacking the catalyst layer, and a coating method, a transfer method, and a combination thereof can be used. The coating method is a method of coating a catalyst layer coating liquid on the electrolyte membrane and drying it for stacking. The transfer method is a method of heating and pressing a catalyst layer transfer sheet having a catalyst layer stacked on a transfer substrate and an electrolyte membrane for stacking. Among them, the transfer method is preferred. As a transfer substrate used in the catalyst layer transfer sheet, the same resin film or substrate as described above can be used.

[0138] Hereinafter, several methods for manufacturing CCM using a transfer method are described by way of example, but the present invention is not limited to these methods.

[0139] As a CCM manufacturing method (I), a manufacturing method having the following steps can be adopted: a step of obtaining an electrolyte membrane having a (B) layer stacked on a (A) layer; a step of obtaining a catalyst layer transfer sheet having a catalyst layer stacked on a transfer substrate; and a step of bringing the (B) layer of the electrolyte membrane and the catalyst layer of the transfer sheet into relative contact and performing heating and pressing.

[0140] In addition, as another method for producing CCM, a method for transferring the (B) layer and the catalyst layer onto the (A) layer together can be used. As the above-mentioned method for producing CCM (II), a method having the following steps can be used: a step of forming the (A) layer, a step of obtaining a catalyst layer / (B) layer transfer sheet in which the catalyst layer and the (B) layer are sequentially stacked on a transfer substrate, and a step of bringing the (A) layer and the (B) layer of the transfer sheet into relative contact and heating and pressing.

[0141] The catalyst layer / (B) layer transfer sheet used in the above-mentioned CCM manufacturing method (II) is useful as a component for obtaining the CCM of an embodiment of the present invention. That is, a component for obtaining the CCM of an embodiment of the present invention is composed of, for example, a catalyst layer / (B) layer transfer sheet in which the catalyst layer and the (B) layer are sequentially stacked on a transfer substrate.

[0142] In addition, in the above-mentioned CCM manufacturing method (II), the (B) layer is composed of two layers, wherein the layer adjacent to the above-mentioned (A) layer is set as the (B-1) layer, and the layer on the side opposite to the (A) layer is set as the (B-2) layer. As a catalyst layer / (B) layer transfer sheet, a catalyst layer / (B-2) layer / (B-1) layer transfer sheet in which a catalyst layer, a (B-2) layer and a (B-1) layer are sequentially stacked on a transfer substrate can be used. The transfer sheet can be used as a component for obtaining a CCM of an embodiment of the present invention. That is, a component for obtaining a CCM of an embodiment of the present invention is composed of, for example, a catalyst layer / (B-2) layer / (B-1) layer transfer sheet in which a catalyst layer, a (B-2) layer and a (B-1) layer are sequentially stacked on a transfer substrate.

[0143] In addition, as a manufacturing method (III) for other CCMs in which the (B) layer is composed of two layers, a manufacturing method comprising the following steps can be adopted: a step of obtaining a stacked body in which a (B-1) layer is stacked on the (A) layer; a step of obtaining a catalyst layer / (B-2) layer transfer sheet in which a catalyst layer and a (B-2) layer are stacked in sequence on a transfer substrate; and a step of bringing the (B-1) layer of the stacked body and the (B-2) layer of the transfer sheet into relative contact and heating and pressing them.

[0144] The catalyst layer / (B-2) layer transfer sheet used in the above-mentioned method (III) for producing CCM is useful as a component for obtaining the CCM of an embodiment of the present invention. That is, a component for obtaining the CCM of an embodiment of the present invention is composed of, for example, a catalyst layer / (B-2) layer transfer sheet in which a catalyst layer and a (B-2) layer are sequentially stacked on a transfer substrate.

[0145] The transfer sheet used in the manufacturing methods (II) and (III) of the above-mentioned CCM, i.e., the parts for obtaining CCM, can be manufactured, for example, by coating a catalyst layer coating liquid on a transfer substrate, coating (B) layer coating liquid before or after drying, and drying. In addition, a method can also be adopted in which a catalyst layer coating liquid and a (B) layer coating liquid are simultaneously coated on a transfer substrate using a multilayer die head or a multilayer slide coater and dried. The coating method is not particularly limited as long as it can be coated into a target shape, for example, die coating, screen printing, spray coating, gravure coating, slide coating, etc. can be used.

[0146] In the above-mentioned CCM manufacturing method, the temperature and pressure of the heating and pressing can be appropriately selected according to the thickness of the (A) layer, the moisture content, the thickness of the (B) layer and the catalyst layer, and the type of the transfer substrate, but from the viewpoints of industrial productivity and thermal decomposition suppression of the polymer electrolyte, it is preferably carried out in the range of 120°C to 250°C. Specifically, it is more preferably carried out at a temperature greater than the glass transition temperature of the polymer contained in the (B) layer and below 200°C. From the viewpoint of protecting the electrolyte membrane, the pressure in the heating and pressing is preferably as weak as possible, for example, in the case of flat plate pressing, it is preferably in the range of 2 to 10 MPa.

[0147] [Membrane Electrode Assembly]

[0148] The membrane electrode assembly includes the CCM and gas diffusion layers (gas diffusion electrodes) disposed on both surfaces thereof. Specifically, the anode gas diffusion layer is disposed and bonded to the anode catalyst layer side of the CCM, and the cathode gas diffusion layer is disposed and bonded to the cathode catalyst layer side.

[0149] The gas diffusion layer is generally composed of a component having gas permeability and electron conductivity, and examples thereof include a carbon porous body or a metal porous body. Examples of the carbon porous body include carbon paper, carbon cloth, carbon mesh, carbon nonwoven fabric, etc. Examples of the metal porous body include metal mesh, foamed metal, metal fabric, metal sintered body, metal nonwoven fabric, etc. Examples of the metal include titanium, aluminum, copper, nickel, nickel-chromium alloy, copper and its alloys, silver, aluminum alloy, zinc alloy, lead alloy, titanium, niobium, tantalum, iron, stainless steel, gold, platinum, etc.

[0150] The gas diffusion layer may be subjected to hydrophobic treatment for preventing gas diffusion and permeability reduction due to water retention, partial hydrophobic treatment and partial hydrophilic treatment for forming a water discharge path, and addition of carbon powder for reducing resistance. In addition, the gas diffusion layer may be provided with a conductive intermediate layer containing at least an inorganic conductive substance and a hydrophobic polymer on the CCM side. In particular, when the gas diffusion layer is composed of a carbon fiber fabric or nonwoven fabric with a large porosity, the provision of a conductive intermediate layer can suppress the performance reduction caused by the penetration of the catalyst solution into the gas diffusion layer.

[0151] The thickness of the gas diffusion layer is preferably 50 μm or more, more preferably 100 μm or more, particularly preferably 150 μm or more, and preferably 1000 μm or less, more preferably 700 μm or less, particularly preferably 500 μm or less.

[0152] The anode gas diffusion layer and the cathode gas diffusion layer may be composed of the same material or different materials. When the membrane electrode assembly is applied to a water electrolysis device, the anode gas diffusion layer and the cathode gas diffusion layer are preferably composed of different materials. For example, the anode gas diffusion layer is preferably composed of a metal porous body, and the cathode gas diffusion layer is preferably composed of a carbon porous body.

[0153] [Application examples]

[0154] The electrolyte membrane of the embodiment of the present invention, the CCM using the electrolyte membrane, and the membrane electrode assembly can be applied to electrochemical applications, for example. Examples of electrochemical applications include fuel cells, redox flow batteries, water electrolysis devices, and electrochemical hydrogen compression devices. Among them, it is preferably applied to water electrolysis hydrogen devices, and particularly preferably applied to water electrolysis devices.

[0155] Example

[0156] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. In addition, various measurement conditions are as follows.

[0157] (1) Molecular weight of polymer

[0158] The number average molecular weight and weight average molecular weight of the polymer solution were measured by gel permeation chromatography (GPC). As an apparatus, HLC-8022GPC produced by Tosoh Corporation was used. As a detector, an ultraviolet detector and a differential refractometer were used. In addition, as a GPC chromatographic column, 2 TSK gel SuperHM-H (inner diameter 6.0mm, length 15cm) manufactured by Tosoh Corporation were used. As a developing solvent, N-methyl-2-pyrrolidone solvent (N-methyl-2-pyrrolidone solvent containing 10mmol / L lithium bromide) was used, and the flow rate was 0.2mL / min, and the number average molecular weight and weight average molecular weight were obtained by standard polystyrene conversion.

[0159] (2) Ion exchange capacity (IEC) of polymer

[0160] The solution obtained by dissolving the polymer in NMP was applied to a PET film and dried to prepare an electrolyte membrane. The ion exchange capacity of the electrolyte membrane was measured by neutralization titration. The measurement was performed three times and the average value was taken.

[0161] After the proton replacement was performed and the electrolyte membrane was thoroughly washed with pure water, the water on the membrane surface was wiped off and then vacuum dried at 100° C. for 12 hours or more to determine the dry weight.

[0162] 50 mL of a 5 mass % sodium sulfate aqueous solution was added to the electrolyte membrane, and the membrane was left to stand for 12 hours to perform ion exchange.

[0163] The sodium sulfate aqueous solution after ion exchange was titrated with a 0.01 mol / L sodium hydroxide aqueous solution. A commercially available phenolphthalein solution for titration at 0.1 w / v% was added as an indicator, and the point at which the solution turned pale purple was regarded as the end point.

[0164] The ion exchange capacity (IEC) was calculated from the following formula.

[0165] IEC (meq / g) = [concentration of sodium hydroxide aqueous solution (mmol / mL) x amount added (mL)] / dry weight of sample (g).

[0166] (3) Determination of the film thickness of each layer by SEM observation and determination of the porosity by image processing

[0167] A shielding plate was placed directly above the sample, and a broad ion beam of argon gas was irradiated from above to perform etching, thereby exposing the cross section of the (B) layer. Then, the cross section of the sample was coated with Pt, and cross-sectional observation was performed under the following conditions.

[0168] Equipment: Field emission scanning electron microscope (FE-SEM) JSM-7800F Prime

[0169] Accelerating voltage: 5.0 kV

[0170] Detection signal: reflected electrons

[0171] Shooting magnification: 500x, 5000x, 50000x

[0172] In the measurement of the film thickness, the thickness of the (A) layer and the (B) layer were measured for an image captured at a 500-fold or 5000-fold imaging magnification, thereby obtaining the thickness of each layer.

[0173] For the measurement of pores, image analysis was applied to images taken at a magnification of 50,000 times. After image noise reduction, background brightness unevenness reduction, and contrast increase were performed using the image analysis software ImageJ, the particle components and pore components in the above image were binarized by machine learning using the plug-in Trainable Weka Segmentation. In the binarization, the same classifier was applied, and each sample was binarized according to the same benchmark. Based on the obtained binary image, the total area (pore area) of the pore components in the two interfaces with a thickness of 10% from the (B) layer was calculated, and the ratio of the pore area to the overall area of ​​the region was calculated to obtain the porosity. The porosity in the interface region with the (A) layer is set as porosity (X1), and the porosity in the interface region on the opposite side of the (A) layer is set as porosity (X2).

[0174] (4) Evaluation of interlayer adhesion (peelability)

[0175] The CCM formed by laminating the catalyst layer on the electrolyte membrane prepared in the examples and comparative examples was cut into a size of 2 cm × 2 cm as a test piece. The bonding state between the electrolyte membrane and the catalyst layer was observed when the test piece was immersed in 20 g of ion exchange water at 80°C for 6 hours, 12 hours, 18 hours and 24 hours, and evaluated according to the following criteria.

[0176] A: No peeling occurred after immersion for 24 hours.

[0177] B: No peeling occurred after immersion for 18 hours, but peeling occurred after immersion for 24 hours.

[0178] C: No peeling occurred after immersion for 12 hours, but peeling occurred after immersion for 18 hours.

[0179] D: No peeling occurred after immersion for 6 hours, but peeling occurred after immersion for 12 hours.

[0180] E: Peeling occurred after immersion for 6 hours.

[0181] (5) Durability evaluation

[0182] For the CCM in which catalyst layers are stacked on both sides of the electrolyte membrane produced in the embodiment and the comparative example, a commercially available gas diffusion electrode 24BCH manufactured by SGL Corporation is stacked on the cathode catalyst layer side as a cathode gas diffusion layer, and a commercially available porous titanium sintered body plate is stacked on the anode catalyst layer side as an anode gas diffusion layer to produce a membrane electrode assembly.

[0183] The membrane electrode assembly prepared above was installed in a JARI standard unit "Ex-1" (electrode area 25 cm 2 ) and connected the unit in such a way that the average CCM pressure was 4 MPa, and the unit temperature was set to 80°C. Deionized water with a conductivity of 1 μS / cm or less was supplied to both the cathode electrode and the anode electrode at a flow rate of 0.2 L / min under atmospheric pressure, and a 2.0 A / cm 2 The current is used to produce hydrogen and oxygen through water electrolysis.

[0184] Durability is tested by continuously applying 2.0A / cm 2 The voltage (V1) at 300 hours of current is evaluated by the rate of increase from the initial applied voltage (V0). The smaller the voltage increase rate, the better the durability. The voltage increase rate is calculated by the following formula.

[0185] Voltage rise rate (%) = (V1-V0) × 100 / (V0)

[0186] [Synthesis example 1]

[0187] (Synthesis of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane (K-DHBP) represented by the following chemical formula (G1))

[0188] 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 added to a 500 mL flask with a stirrer, a thermometer and a distillation tube and dissolved. Then, the mixture was stirred at 78-82°C for 2 hours. Furthermore, the internal temperature was gradually raised to 120°C and heated until the distillation of methyl formate, methanol and trimethyl orthoformate was completely stopped. After the reaction solution was cooled to room temperature, the reaction solution was diluted with ethyl acetate and the organic layer was washed with 100 mL of a 5% potassium carbonate aqueous solution. After separation, the solvent of the organic layer was distilled off. 80 mL of dichloromethane was added to the residue to precipitate crystals, which were filtered and dried to obtain 52.0 g of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane represented by the following chemical formula (G1). The crystals were analyzed by gas chromatography (GC), and the results showed that the crystals contained 99.9% of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane and 0.1% of 4,4'-dihydroxybenzophenone, with a purity of 99.9%.

[0189]

[0190] [Synthesis example 2]

[0191] (Synthesis of 3,3'-sodium disulfonate-4,4'-difluorobenzophenone represented by the following chemical formula (G2))

[0192] In 150 mL of fuming sulfuric acid (50% SO3) (Fujifilm Wako Pure Chemical Industries, Ltd. reagent), 109.1 g of 4,4'-difluorobenzophenone was reacted at 100°C for 10 hours. Then, it was added little by little into a large amount of water, neutralized with NaOH, and 200 g of common salt (NaCl) was added to precipitate the synthetic product. The precipitate obtained was filtered and recrystallized with ethanol aqueous solution to obtain 3,3'-disulfonic acid sodium-4,4'-difluorobenzophenone represented by the following chemical formula (G2). The purity was 99.3%.

[0193]

[0194] [Synthesis example 3]

[0195] (Synthesis of nonionic oligomer a1 represented by the following general formula (G3))

[0196] In a 2000mL SUS polymerization apparatus equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark water separator, 16.59g of potassium carbonate (Aldrich reagent, 120mmol), 25.83g of K-DHBP obtained in Synthesis Example 1 (100mmol), and 20.3g of 4,4'-difluorobenzophenone (Aldrich reagent, 93mmol) were added. After nitrogen substitution in the apparatus, 300mL of N-methylpyrrolidone (NMP) and 100mL of toluene were added, and after dehydration at 150°C, the temperature was raised to remove toluene, and polymerization was carried out at 170°C for 3 hours. Reprecipitation and purification were carried out with a large amount of methanol to obtain the terminal hydroxyl body of the nonionic oligomer a1. The number average molecular weight of the terminal hydroxyl body of the nonionic oligomer a1 is 10,000.

[0197] In a 500mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark water separator, 1.1g of potassium carbonate (Sigma Aldrich Japan (same) reagent, 8mmol) and 20.0g (2mmol) of the terminal hydroxyl body of the above non-ionic oligomer a1 were added. After nitrogen substitution in the device, 100mL of NMP and 30mL of toluene were added, and the toluene was removed by heating after dehydration at 100°C. 2.2g of hexafluorobenzene (Sigma Aldrich Japan (same) reagent, 12mmol) was further added, and the reaction was carried out at 105°C for 12 hours. Reprecipitation and purification were carried out with a large amount of isopropanol to obtain the non-ionic oligomer a1 (terminal: fluorine group) represented by the following general formula (G3). The number average molecular weight is 11000.

[0198]

[0199] [Synthesis Example 4]

[0200] (Synthesis of Ionic Oligomer a2 Represented by the Following General Formula (G4))

[0201] In a 2000 mL SUS polymerization apparatus equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark water separator, 27.6 g of potassium carbonate (Sigma Aldrich Japan (same) reagent, 200 mmol), 12.9 g (50 mmol) of K-DHBP obtained in Synthesis Example 1, 9.3 g (Sigma Aldrich Japan (same) reagent, 50 mmol), 39.3 g (93 mmol) of 3,3'-sodium disulfonate-4,4'-difluorobenzophenone obtained in Synthesis Example 2, and 17.9 g of 18-crown-6 (Fujifilm Wako Pure Chemical Industries, Ltd., 82 mmol) were added. After nitrogen substitution in the apparatus, 300 mL of NMP and 100 mL of toluene were added, and after dehydration at 150°C, the toluene was removed by heating, and polymerization was carried out at 170°C for 6 hours. Reprecipitation and purification were carried out with a large amount of isopropanol to obtain an ionic oligomer a2 (terminal: hydroxyl group) represented by the following general formula (G4). The number average molecular weight is 16000. In the general formula (G4), M represents H, Na or K.

[0202]

[0203] [Synthesis example 5]

[0204] (Synthesis of neopentyl 3-(2,5-dichlorobenzoyl)benzenesulfonate represented by the following chemical formula (G5))

[0205] Add 245g (2.1mol) of chlorosulfonic acid to a 3L three-necked flask with a stirrer and a cooling tube, then add 105g (420mmol) of 2,5-dichlorobenzophenone, and react in an oil bath at 100°C for 8 hours. After the specified time, slowly pour the reaction solution into 1000g of crushed ice and extract with ethyl acetate. Wash the organic layer with brine, dry it with magnesium sulfate, and then distill off the ethyl acetate to obtain pale yellow crude crystals of 3-(2,5-dichlorobenzoyl)benzenesulfonyl chloride. Use the crude crystals directly in the next step without purification.

[0206] Add 41.1 g (462 mmol) of 2,2-dimethyl-1-propanol (neopentyl alcohol) to 300 mL of pyridine and cool to about 10°C. Slowly add the crude crystals obtained above over a period of about 30 minutes. After all are added, stir for another 30 minutes to react. After the reaction, pour the reaction solution into 1000 mL of hydrochloric acid water and recover the precipitated solid. Dissolve the obtained solid in ethyl acetate, wash with sodium bicarbonate aqueous solution and brine, dry with magnesium sulfate, and then distill off the ethyl acetate to obtain crude crystals. Recrystallize it with methanol to obtain white crystals of 3-(2,5-dichlorobenzoyl)benzenesulfonic acid neopentyl ester shown in the following chemical formula (G5).

[0207]

[0208] [Synthesis example 6]

[0209] (Synthesis of an oligomer not containing an ionic group represented by the following general formula (G6))

[0210] 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 nitrogen inlet, 49.4g (0.29mol) of 2,6-dichlorobenzonitrile, 88.4g (0.26mol) of 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, and 47.3g (0.34mol) of potassium carbonate were weighed and added. After replacing the atmosphere in the flask with nitrogen, 346mL of sulfolane and 173mL of toluene were added and stirred. The flask was placed in an oil bath and heated to reflux at 150°C. The water generated by the reaction was allowed to azeotropically coexist with toluene and removed from the system using a Dean-Stark tube while the reaction was carried out. After about 3 hours, almost no water was observed to be generated. Most of the toluene was removed while gradually increasing the reaction temperature, and then the reaction was continued at 200°C for 3 hours. Then 12.3g (0.072mol) of 2,6-dichlorobenzonitrile was added and the reaction was continued for another 5 hours.

[0211] After the obtained reaction solution was cooled, 100 mL of toluene was added for dilution. The precipitate of the inorganic compound produced as a by-product was filtered out, and the filtrate was put into 2 L of methanol. The precipitated product was filtered, recovered, dried, and dissolved in 250 mL of tetrahydrofuran. It was reprecipitated in 2 L of methanol to obtain 107 g of the target oligomer represented by the following general formula (G6). The number average molecular weight was 11,000.

[0212]

[0213] [Synthesis Example 7]

[0214] (Synthesis of polyethersulfone (PES)-based block copolymer precursor b1 composed of a segment represented by the following chemical formula (G8) and a segment represented by the following general formula (G9))

[0215] 1.62 g of anhydrous nickel chloride and 15 mL of dimethyl sulfoxide were mixed and adjusted to 70° C. 2.15 g of 2,2′-bipyridine was added thereto, and the mixture was stirred at the same temperature for 10 minutes to prepare a nickel-containing solution.

[0216] In the solution obtained by dissolving 1.49g of 2,5-dichlorobenzenesulfonic acid (2,2-dimethylpropyl) and 0.50g of Sumika Ecocell PES5200P (manufactured by Sumitomo Chemical Co., Ltd., Mn=40000, Mw=94000) represented by the following general formula (G7) in 5mL of dimethyl sulfoxide, 1.23g of zinc powder was added and adjusted to 70°C. The above nickel-containing solution was injected thereinto, and a polymerization reaction was carried out at 70°C for 4 hours. The reaction mixture was added to 60mL of methanol, and then 60mL of 6mol / L hydrochloric acid was added and stirred for 1 hour. The precipitated solid was separated by filtration and dried to obtain 1.62g of an off-white block copolymer precursor b1 containing segments represented by the following general formula (G8) and the following general formula (G9), with a yield of 99%. The weight average molecular weight is 230,000.

[0217]

[0218] [Preparation of coating solution for layer (A)]

[0219] Coating solutions p1 to p4 containing various polymer electrolytes were prepared according to the following procedures.

[0220] [Coating liquid p1]: Coating liquid containing polyetherketone-based block copolymer P1

[0221] In a 2000 mL SUS polymerization apparatus equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark water separator, 16 g of ionic oligomer a2 and 11 g of nonionic oligomer a1 were added, and NMP was added to make the total amount of oligomers added 7 wt%, and the reaction was carried out at 105°C for 24 hours.

[0222] Reprecipitate in a large amount of isopropanol / NMP mixed solution (weight ratio 2 / 1), recover the obtained precipitate by filtration, and wash with a large amount of isopropanol to obtain block copolymer P1. The weight average molecular weight is 340,000. The ion exchange capacity (IEC) of the block copolymer P1 is 2.1meq / g. Then, the block copolymer P1 is dissolved in NMP and pressure filtered using a 1μm polypropylene filter to obtain a coating liquid P1 (polymer electrolyte concentration is 13% by mass). The viscosity of the coating liquid P1 is 1300mPa·s.

[0223] [Coating liquid p2]: Coating liquid containing polyetherketone random copolymer P2

[0224] 129 g of 2,2-bis(4-hydroxyphenyl)-1,3-dioxolane synthesized in Synthesis Example 1, 93 g of 4,4'-biphenol (Sigma Aldrich Japan (same) reagent) and 422 g (1.0 mol) of 3,3'-sodium disulfonate-4,4'-difluorobenzophenone synthesized in Synthesis Example 2 were placed in a 5L reaction container equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark water separator. After replacing the atmosphere in the container with nitrogen, 3000 g of NMP, 450 g of toluene, and 232 g of 18-crown ether-6 (Fujifilm Wako Pure Chemical Industries, Ltd. reagent) were added. After confirming that all the monomers were dissolved, 304 g of potassium carbonate (Sigma Aldrich Japan (same) reagent) was added, and dehydration was carried out at 160°C while reflux. Then, the temperature was raised to remove the toluene, and desalting polycondensation was carried out at 200°C for 1 hour. The obtained random copolymer P2 had a weight average molecular weight of 320,000 and an ion exchange capacity (IEC) of 2.1.

[0225] NMP was then added to dilute the polymer stock solution so that the viscosity of the polymer stock solution was 500 mPa·s. An angle rotor RA-800 was set in an inverter·small high-speed cooling centrifuge (model 6930) manufactured by Kubota Corporation, and the polymer stock solution was directly centrifuged at 25°C with a centrifugal force of 20,000 G for 30 minutes. The precipitated solids (sludge) and the supernatant (coating liquid) were separated very cleanly, so the supernatant was recovered. Next, while stirring, vacuum distillation was performed at 80°C to remove NMP until the polymer concentration reached 14% by mass, and then pressure filtration was performed using a 5μm polyethylene filter to obtain a coating liquid p2. The viscosity of the coating liquid p2 was 1000 mPa·s.

[0226] [Coating liquid p3]: A coating liquid containing a polyarylene block copolymer P3 represented by the following general formula (G10):

[0227] Dry N,N-dimethylacetamide (DMA C )540mL was added under nitrogen to a mixture of 135.0g (0.336mol) of neopentyl 3-(2,5-dichlorobenzoyl)benzenesulfonate, 40.7g (5.6mol) of the nonionic oligomer represented by the general formula (G6) synthesized in Synthesis Example 6, 6.71g (16.8mmol) of 2,5-dichloro-4'-(1-imidazolyl)benzophenone, 6.71g (10.3mmol) of bis(triphenylphosphine)nickel dichloride, 35.9g (0.137mol) of triphenylphosphine, 1.54g (10.3mmol) of sodium iodide and 53.7g (0.821mol) of zinc.

[0228] The reaction system was heated under stirring (finally heated to 79° C.) and reacted for 3 hours. During the reaction, the viscosity of the system was observed to increase. The polymerization reaction solution was diluted with 730 mL of DMAc, stirred for 30 minutes, and filtered using diatomaceous earth as a filter aid.

[0229] The filtrate was concentrated with an evaporator, and 43.8 g (0.505 mol) of lithium bromide was added to the filtrate, and the reaction was carried out for 7 hours at an internal temperature of 110°C under a nitrogen atmosphere. After the reaction, it was cooled to room temperature, and 4 L of acetone was injected to solidify. The solid was collected by filtration and air-dried, then crushed with a blender, and washed with 1500 ml of 1N hydrochloric acid while stirring. After filtration, the product was washed with ion exchange water until the pH of the washing liquid was above 5. Then, it was dried at 80°C overnight to obtain 23.0 g of polyarylene block copolymer P3. The weight average molecular weight of the polyarylene block copolymer P3 is 190,000, and the ion exchange capacity (IEC) is 2.0. The obtained polyarylene block copolymer P3 was dissolved in a mixed organic solvent of N-methyl-2-pyrrolidone / methanol = 30 / 70 (mass %) to 0.1 g / g, and a coating liquid p3 was obtained. The viscosity of the coating liquid p3 is 1200 mPa·s.

[0230]

[0231] [Coating liquid p4]: Coating liquid containing polyethersulfone block copolymer P4

[0232] 0.23 g of the block copolymer precursor b1 obtained in Synthesis Example 7 was measured and added to a mixed solution of 0.16 g of lithium bromide monohydrate and 8 mL of NMP, and reacted at 120°C for 24 hours. The reaction mixture was poured 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 an off-white block copolymer P4 composed of a segment represented by the above general formula (G9) and a segment represented by the following chemical formula (G11). The weight average molecular weight of the obtained polyethersulfone block copolymer P4 was 190,000, and the ion exchange capacity (IEC) was 2.0. The obtained polyethersulfone block copolymer P4 was dissolved in an organic solvent of N-methyl-2-pyrrolidone / methanol = 30 / 70 (mass %) to 0.1 g / g, and a coating liquid p4 was obtained. The viscosity of the coating liquid p4 was 1300 mPa·s.

[0233]

[0234] [Preparation of coating solution for layer (B)]

[0235] Coating solutions q1 to q10 were prepared according to the following procedures.

[0236] [Coating liquid q1]

[0237] Particles: Carbon black (VULCAN (registered trademark) XC72 manufactured by Cabot Corporation: average particle size 30 nm) 10 parts by mass

[0238] Polymer: Fluorine-based polymer electrolyte manufactured by Chemours Corporation ["Nafion" (registered trademark) Model D2020], 8 parts by mass in terms of solid content

[0239] Solvent: A mixed solvent of water and n-propanol with a mass ratio of 4:6

[0240] The particles and polymer were dispersed in a solvent using a bead mill to prepare a coating liquid q1 having a solid content concentration of 10% by mass. The ratio (P / F) of the mass of the polymer (P) to the mass of the particles (F) in the coating liquid q1 was 0.8.

[0241] [Preparation of coating liquid q2 to q10]

[0242] Coating liquids q2 to q7 were prepared in the same manner as coating liquid q1, except that the ratio of polymer to particles (P / F) was changed as shown in Table 1. Coating liquid q8 was prepared in the same manner as coating liquid q1, except that particles were not used. Coating liquid q9 was prepared in the same manner as coating liquid q1, except that particles were changed from carbon black to cerium (IV) oxide (average particle size 50 nm) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Co., Ltd. Coating liquid q10 was prepared in the same manner as coating liquid q8, except that the polymer was changed to PVDF (polyvinylidene fluoride) manufactured by Solvey.

[0243] Table 1

[0244] Coating liquid particle polymer P / F q1 Carbon Black "nafion" 0.8 q2 Carbon Black "nafion" 0.4 q3 Carbon Black "nafion" 1.2 q4 Carbon Black "nafion" 1.6 q5 Carbon Black "nafion" 1.8 q6 Carbon Black "nafion" 2.0 q7 Carbon Black "nafion" 3.0 q8 "nafion" q9 Cerium Oxide "nafion" 0.8 q10 PVDF

[0245] [Preparation of anode catalyst layer transfer sheet]

[0246] The following anode catalyst layer coating solution was cast onto a commercially available polytetrafluoroethylene film so that the iridium content was 1.0 mg / cm 2 , and dried at 100° C. for 4 hours to prepare an anode catalyst layer transfer sheet.

[0247] <Anode Catalyst Layer Coating Solution>

[0248] The preparation was carried out by dispersing 10 parts by mass of particles (IrO2 catalyst ElystIr75 0480 (Ir content 75%) manufactured by Umicore) and 1.2 parts by mass of a fluorine-based polymer electrolyte ("Nafion" (registered trademark) model D2020 manufactured by Chemizer Co., Ltd.) in terms of solid content in 28.8 parts by mass of water, 30 parts by mass of n-propanol and 30 parts by mass of tert-butanol.

[0249] [Preparation of cathode catalyst layer transfer sheet]

[0250] The following cathode catalyst layer coating solution was cast onto a commercially available polytetrafluoroethylene film so that the amount of platinum was 0.3 mg / cm 2 , and dried at 100° C. for 4 hours to prepare a cathode catalyst layer transfer sheet.

[0251] <Cathode Catalyst Layer Coating Solution>

[0252] The catalyst particles (10 parts by mass of platinum catalyst-supported carbon particles TEC10E50E (platinum support rate 50% by mass) manufactured by Tanaka Precious Metals Industry Co., Ltd.) and 5 parts by mass of a fluorine-based polymer electrolyte (Nafion (registered trademark) model D2020 manufactured by Chemizer Co., Ltd.) were dispersed in 25 parts by mass of water, 30 parts by mass of n-propanol and 30 parts by mass of tert-butanol to prepare the product.

[0253] [Example 1]

[0254] The electrolyte membrane was produced according to the following procedure.

[0255] [Production of (A) layer]

[0256] The PET film "LumiLa" (registered trademark) 125T60 manufactured by Toray Industries, Ltd. was bonded and fixed to a SUS plate using "Kaputon" (registered trademark) tape. The coating solution p1 was cast on the PET film and dried at 100°C for 4 hours to obtain a thin film. The thin film was immersed in a 10% by mass sulfuric acid aqueous solution at 80°C for 24 hours, subjected to proton substitution and deprotection reactions, and then immersed in a large excess of pure water for 24 hours and fully washed to obtain a layer (A) (film thickness 100 μm).

[0257] (B) Layer stacking

[0258] The coating liquid q1 was cast on the (A) layer and dried at 100°C for 4 hours, thereby laminating the (B-1) layer (film thickness 3 μm) on the (A) layer. Next, the coating liquid q8 was cast on the (B-1) layer and dried at 100°C for 4 hours, thereby laminating the (B-2) layer (film thickness 3 μm).

[0259] [Examples 2 to 11]

[0260] An electrolyte membrane was prepared in the same manner as in Example 1 except that the coating liquid of the (B-1) layer and the coating liquid of the (B-2) layer were changed as shown in Table 2.

[0261] [Examples 12 to 14]

[0262] An electrolyte membrane was prepared in the same manner as in Example 1 except that the coating liquid p1 for the (A) layer was changed to that shown in Table 2.

[0263] [Comparative Example 1]

[0264] An electrolyte membrane was obtained in the same manner as in Example 1 except that the (B) layer was not laminated.

[0265] [Comparative Example 2]

[0266] The (A) layer is prepared in the same manner as in Example 1, and the coating liquid q8 is cast on the (A) layer and dried at 100°C for 4 hours, thereby stacking a single (B) layer (film thickness 6 μm) consisting only of a polymer on the (A) layer to produce an electrolyte membrane.

[0267] [Comparative Example 3]

[0268] The (A) layer is prepared in the same manner as in Example 1, and the coating liquid q7 is cast on the (A) layer and dried at 100°C for 4 hours, thereby stacking a single (B) layer (film thickness 6 μm) containing particles and polymer on the (A) layer to produce an electrolyte membrane.

[0269] [Example 15]

[0270] Follow the instructions below to make CCM.

[0271] [Production of (A) layer]

[0272] In the same manner as in Example 1, the (A) layer was prepared.

[0273] [Preparation of Catalyst Layer / (B) Layer Transfer Sheet]

[0274] The coating liquid q8 was cast on the catalyst layer of the anode catalyst layer transfer sheet, and dried at 100°C for 4 hours to laminate the (B-2) layer (film thickness 3 μm), and then the coating liquid q1 was cast on the (B-2) layer, and dried at 100°C for 4 hours to laminate the (B-1) layer (film thickness 3 μm). The catalyst layer / (B) layer transfer sheet is a catalyst layer / (B-2) layer / (B-1) layer transfer sheet in which a catalyst layer and a (B) layer (((B-2) layer / (B-1) layer) are laminated in sequence on a transfer substrate, and is used to prepare a CCM.

[0275] [Production of CCM]

[0276] The (A) layer and the (B-1) layer of the transfer sheet prepared above are overlapped in a relative contact manner, heated and pressed at 150°C and 5 MPa for 3 minutes, cooled to below 40°C under pressure, and then the pressure is released to obtain CCM.

[0277] [Example 16]

[0278] Prepare CCM according to the following instructions.

[0279] [Preparation of Laminated Body of Layer (A) and Layer (B-1)]

[0280] The coating liquid q1 was cast on the layer (A) prepared in the same manner as in Example 1, and dried at 100°C for 4 hours to obtain a laminate having the layer (B-1) (film thickness 3 μm) laminated on the layer (A).

[0281] [Preparation of Catalyst Layer / (B-2) Layer Transfer Sheet]

[0282] The coating solution q8 was cast on the catalyst layer of the anode catalyst layer transfer sheet and dried at 100°C for 4 hours to laminate the (B-2) layer (film thickness 3 μm). The catalyst layer / (B-2) layer transfer sheet is formed by laminating the catalyst layer and the (B-2) layer in sequence on the transfer substrate, and is used to prepare CCM.

[0283] [CCM Production]

[0284] The (B-1) layer of the above-made stack and the (B-2) layer of the catalyst layer / (B-2) layer transfer sheet are overlapped in a relative contact manner, heated and pressed at 150°C and 5MPa for 3 minutes, cooled to below 40°C under pressure, and then the pressure is released to obtain CCM.

[0285] [evaluate]

[0286] The anode catalyst layer transfer sheet was stacked on the (B) layer side of the electrolyte membrane produced in the above Examples 1 to 14 and Comparative Examples 1 to 3, and heated and pressed at 150°C and 5 MPa for 3 minutes, and then cooled to below 40°C under pressure, and then the pressure was released to obtain a CCM. For these CCMs and the CCMs produced in Examples 15 and 16, the adhesion between the electrolyte membrane and the catalyst layer was evaluated according to the above "(4) Evaluation of interlayer adhesion (peelability)". The results are shown in Table 2.

[0287]

[0288] In the table, particle "CB" represents carbon black, and "Ce" represents cerium oxide.

[0289] [Example 21]

[0290] The electrolyte membrane was produced according to the following procedure.

[0291] [Production of (A) layer]

[0292] In the same manner as in Example 1, the (A) layer was prepared.

[0293] (B) Layer stacking

[0294] The coating liquid q1 was cast on the (A) layer and dried at 100°C for 4 hours, thereby laminating the (B-1) layer (film thickness 5 μm) on the (A) layer. Next, the coating liquid q4 was cast on the (B-1) layer and dried at 100°C for 4 hours, thereby laminating the (B-2) layer (film thickness 5 μm).

[0295] [Example 22]

[0296] An electrolyte membrane was produced in the same manner as in Example 21 except that the coating liquid for the (B-2) layer was changed to coating liquid q5.

[0297] [Comparative Example 21]

[0298] An electrolyte membrane was obtained in the same manner as in Example 21 except that the (B) layer was not laminated.

[0299] [evaluate]

[0300] The cathode catalyst layer transfer sheet was stacked on the (B) layer side of the electrolyte membrane produced in the above-mentioned embodiment and comparative example, and heated and pressed at 150°C and 5MPa for 3 minutes, cooled to below 40°C under pressure, and then released to obtain CCM. For these CCMs, the bonding properties between the electrolyte membrane and the catalyst layer were evaluated according to the above-mentioned "(4) Evaluation of interlayer bonding (peelability)". The results are shown in Table 3.

[0301] Table 3

[0302]

[0303] [Example 31]

[0304] The electrolyte membrane was produced according to the following procedure.

[0305] [Production of (A) layer]

[0306] In the same manner as in Example 1, the (A) layer was prepared.

[0307] [Preparation of (B) Layer Transfer Sheet D1]

[0308] The coating liquid q8 was cast on a commercially available polytetrafluoroethylene film and dried at 100°C for 4 hours to laminate the (B-2) layer (film thickness 3 μm). Furthermore, the coating liquid q1 was cast on the (B-2) layer and dried at 100°C for 4 hours to laminate the (B-1) layer (film thickness 3 μm) to obtain the (B) layer transfer sheet D1.

[0309] [Production of (B) Layer Transfer Sheet D2]

[0310] The coating liquid q4 was cast on a commercially available polytetrafluoroethylene film and dried at 100°C for 4 hours to laminate the (B-2) layer (film thickness 5 μm). Furthermore, the coating liquid q1 was cast on the (B-2) layer and dried at 100°C for 4 hours to laminate the (B-1) layer (film thickness 5 μm) to obtain the (B) layer transfer sheet D2.

[0311] (B) Layer stacking

[0312] The (A) layer is peeled off from the PET film, and the (B-1) layer side of the (B) layer transfer sheet D1 is overlapped on one side (anode side) of the (A) layer, and the (B-1) layer side of the (B) layer transfer sheet D2 is overlapped on the other side (cathode side) of the (A) layer. Heat pressing is performed at 150°C and 5MPa for 3 minutes, and the temperature is reduced to below 40°C under pressure, and then the pressure is released to produce an electrolyte membrane.

[0313] [Example 32]

[0314] [Production of (B) Layer Transfer Sheet D3]

[0315] In the preparation of the (B) layer transfer sheet D1, a (B) layer transfer sheet D3 was prepared in the same manner except that the (B-1) layer coating liquid q1 was changed to the coating liquid q9.

[0316] (B) Layer stacking

[0317] The (A) layer is peeled off from the PET film, and the (B-1) layer side of the (B) layer transfer sheet D3 is overlapped on one side (anode side) of the (A) layer, and the (B-1) layer side of the (B) layer transfer sheet D2 is overlapped on the other side (cathode side) of the (A) layer. Heat pressing is performed at 150°C and 5MPa for 3 minutes, and the temperature is reduced to below 40°C under pressure. Then the pressure is released to produce an electrolyte membrane.

[0318] [Example 33]

[0319] [Production of (B) Layer Transfer Sheet D4]

[0320] In the preparation of the (B) layer transfer sheet D1, a (B) layer transfer sheet D4 was prepared in the same manner except that the (B-2) layer coating liquid q8 was replaced by the coating liquid q10.

[0321] (B) Layer stacking

[0322] The (A) layer is peeled off from the PET film, and the (B-1) layer side of the (B) layer transfer sheet D4 is overlapped on one side (anode side) of the (A) layer, and the (B-1) layer side of the (B) layer transfer sheet D2 is overlapped on the other side (cathode side) of the (A) layer. Heat pressing is performed at 150°C and 5MPa for 3 minutes, and the temperature is reduced to below 40°C under pressure. Then the pressure is released to produce an electrolyte membrane.

[0323] [Examples 34 to 36]

[0324] An electrolyte membrane was prepared in the same manner as in Example 31 except that the coating liquid p1 for layer (A) was changed to that shown in Table 4.

[0325] [Comparative Example 31]

[0326] An electrolyte membrane was produced in the same manner as in Example 31 except that the (B) layer was not laminated.

[0327] [evaluate]

[0328] The anode catalyst layer transfer sheet was stacked on the anode side (B) layer of the electrolyte membrane produced in the above-mentioned embodiment and comparative example, and the cathode catalyst layer transfer sheet was stacked on the cathode side (B) layer of the electrolyte membrane, and heated and pressed at 150°C and 5MPa for 3 minutes, and then cooled to below 40°C under pressure, and then the pressure was released to obtain CCM. For these CCMs, the durability was evaluated according to the above-mentioned "(5) Evaluation of durability". The results are shown in Table 4.

[0329] Table 4

[0330]

[0331] Description of the accompanying drawings

[0332] 1.2 Electrolyte membrane

[0333] Floor 10(A)

[0334] 20, 20a, 20b (B) layer

[0335] 21, 21a, 21b (B) layer (A) side interface region

[0336] 22, 22a, 22b (B) layer on the opposite side of the (A) layer interface region 30, 40 catalyst layer

[0337] 50Anode catalyst layer

[0338] 60 cathode catalyst layer

[0339] 100, 200 Electrolyte membrane with catalyst layer

Claims

1. An electrolyte membrane comprising a layer A containing a polymer electrolyte and a layer B located on at least one side of the layer A, wherein a porosity X1 of the layer B in an interface region with the layer A is higher than a porosity X2 of the layer B in an interface region on a side opposite to the layer A. 2 . The electrolyte membrane according to claim 1 , wherein a porosity ratio X2 / X1 of the porosity X1 to the porosity X2 is 0.90 or less. 3 . The electrolyte membrane according to claim 1 , wherein the porosity X1 is greater than or equal to 20%, and the porosity X2 is less than 20%. 4 . The electrolyte membrane according to claim 1 , wherein the layer B contains at least particles and a polymer. The electrolyte membrane according to claim 4 , wherein the particles are carbon particles. The electrolyte membrane according to claim 4 or 5, wherein the polymer is a fluorine-based polymer. 7 . The electrolyte membrane according to claim 1 , wherein the B layer is composed of at least two layers, and among these layers, the layer adjacent to the A layer has the highest porosity.

8. The electrolyte membrane according to claim 1, wherein the B layer is composed of two layers, a layer adjacent to the A layer is a B-1 layer, and a layer on the opposite side to the A layer is a B-2 layer. 9 . The electrolyte membrane according to claim 1 , wherein the thickness of the A layer is 30 μm or more and 250 μm or less, and the thickness of the B layer is 0.5 μm or more and 20 μm or less. 10 . The electrolyte membrane according to claim 1 , comprising the B layer on both surfaces of the A layer. 11 . An electrolyte membrane with a catalyst layer, comprising the catalyst layer on one or both surfaces of the electrolyte membrane according to claim 1 .

12. An electrolyte membrane with a catalyst layer as described in claim 11, wherein the catalyst layer contains catalyst particles and a polymer electrolyte, the mass ratio C / I of the content C of the catalyst particles to the content I of the polymer electrolyte is greater than 4.0, and the porosity X2 of the B layer adjacent to the catalyst layer is less than 12%. 13 . The electrolyte membrane with a catalyst layer according to claim 12 , wherein the catalyst layer is an anode catalyst layer.

14. An electrolyte membrane with a catalyst layer as described in claim 11, wherein the catalyst layer contains catalyst particles and a polymer electrolyte, the mass ratio C / I of the content C of the catalyst particles to the content I of the polymer electrolyte is less than 4.0, and the porosity X2 of the B layer adjacent to the catalyst layer is less than 20%. 15 . The electrolyte membrane with a catalyst layer according to claim 14 , wherein the catalyst layer is a cathode catalyst layer.

16. An electrolyte membrane with a catalyst layer as described in any one of claims 11 to 15, comprising an anode catalyst layer on one surface of the electrolyte membrane and a cathode catalyst layer on the other surface, wherein the porosity X2 in the B layer on the anode catalyst layer side is less than 12%, and the porosity X2 in the B layer on the cathode catalyst layer side is less than 20%. 17 . The catalyst-layered electrolyte membrane according to claim 11 , wherein the polymer electrolyte contained in the layer A of the electrolyte membrane and the polymer electrolyte contained in the catalyst layer are of different types. 18 . The catalyst layer-carrying electrolyte membrane according to claim 17 , wherein the layer B of the electrolyte membrane contains a polymer of the same type as that of the catalyst layer. 19 . The catalyst layer-carrying electrolyte membrane according to claim 17 , wherein the A layer contains a hydrocarbon-based polymer electrolyte, the catalyst layer contains a fluorine-based polymer electrolyte, and the B layer contains a fluorine-based polymer. 20 . A membrane electrode assembly comprising the electrolyte membrane with a catalyst layer according to claim 11 .

21. A water electrolysis device comprising the membrane electrode assembly according to claim 20.

22. A catalyst layer / B layer transfer sheet, the transfer sheet being used for manufacturing the electrolyte membrane with a catalyst layer according to any one of claims 11 to 19, The catalyst layer and the B layer are sequentially stacked on the transfer substrate, and the porosity X1 of the interface region of the B layer opposite to the catalyst layer is higher than the porosity X2 of the interface region of the B layer with the catalyst layer.

23. The catalyst layer / B layer transfer sheet according to claim 22, wherein the B layer is composed of two layers, a B-1 layer and a B-2 layer, and the catalyst layer, the B-2 layer and the B-1 layer are sequentially stacked on the transfer substrate.

24. The catalyst layer / B layer transfer sheet according to claim 22, wherein the B layer is composed of two layers, a B-1 layer and a B-2 layer, and the catalyst layer and the B-2 layer are sequentially stacked on the transfer substrate.

25. A method for manufacturing an electrolyte membrane with a catalyst layer, comprising an electrolyte membrane and a catalyst layer provided on one or both surfaces of the electrolyte membrane, wherein the electrolyte membrane comprises a layer A containing a polymer electrolyte and a layer B provided on at least one surface of the layer A, the method comprising the following steps: A step of laminating the B layer on the A layer to obtain the electrolyte membrane according to any one of claims 1 to 10, a step of laminating the catalyst layer on a transfer substrate to produce a catalyst layer transfer sheet, and A step of heating and pressing the surface of the electrolyte membrane on which the B layer is laminated and the surface of the transfer sheet on which the catalyst layer is laminated are brought into contact with each other.

26. A method for manufacturing an electrolyte membrane with a catalyst layer, comprising an electrolyte membrane and a catalyst layer provided on one or both surfaces of the electrolyte membrane, wherein the electrolyte membrane comprises a layer A containing a polymer electrolyte and a layer B provided on at least one surface of the layer A, the method comprising the following steps: A step of sequentially laminating a catalyst layer and a B layer on a transfer substrate to obtain the catalyst layer / B layer transfer sheet according to claim 22, and A step of heating and pressing the catalyst layer / B layer transfer sheet so that the surface on which the B layer is laminated is in contact with at least one surface of the A layer.

27. A method for manufacturing an electrolyte membrane with a catalyst layer, comprising an electrolyte membrane and a catalyst layer provided on one or both surfaces of the electrolyte membrane, wherein the electrolyte membrane comprises a layer A containing a polymer electrolyte and a layer B provided on at least one surface of the layer A, The B layer is composed of two layers, the layer adjacent to the A layer is set as the B-1 layer, and the layer on the side opposite to the A layer is set as the B-2 layer, and the manufacturing method includes the following steps: A step of laminating a B-1 layer on the A layer to obtain a laminate, A step of sequentially stacking a catalyst layer and a B-2 layer on a transfer substrate to obtain a catalyst layer / B-2 layer transfer sheet according to claim 24, and a step of heating and pressing the surface of the laminate on which the B-1 layer is laminated and the surface of the transfer sheet on which the B-2 layer is laminated so as to face each other; The porosity X1 of the interface region of the B layer with the A layer is higher than the porosity X2 of the interface region of the B layer on the side opposite to the A layer.

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