WO2014157389A1

WO2014157389A1 - Electrolyte membrane composition, solid polymer electrolyte membrane, method of producing said electrolyte membrane, membrane-electrode assembly, solid polymer-type fuel cell, and water electrolysis cell and water electrolysis apparatus

Info

Publication number: WO2014157389A1
Application number: PCT/JP2014/058640
Authority: WO
Inventors: 法寛山本; 宣彰若林; 敏明門田; 翔平藤下
Original assignee: Jsr株式会社
Priority date: 2013-03-28
Filing date: 2014-03-26
Publication date: 2014-10-02
Also published as: JPWO2014157389A1

Abstract

The present invention relates to an electrolyte membrane composition, solid polymer electrolyte membrane, method of producing said electrolyte membrane, membrane-electrode assembly, solid polymer-type fuel cell, water electrolysis cell, and water electrolysis apparatus. This electrolyte membrane composition comprises a polymer (A) that has an ion exchange group, and a polymer (B) that has an arylene sulfide backbone and is soluble in an organic solvent.

Description

Composition for electrolyte membrane, solid polymer electrolyte membrane, method for producing the electrolyte membrane, membrane-electrode assembly, solid polymer fuel cell, water electrolysis cell, and water electrolysis apparatus

The present invention relates to an electrolyte membrane composition, a solid polymer electrolyte membrane, a method for producing the electrolyte membrane, a membrane-electrode assembly, a solid polymer fuel cell, a water electrolysis cell, and a water electrolysis apparatus.

A fuel cell is a power generator that directly takes out electricity by electrochemically reacting hydrogen gas obtained by reforming various hydrocarbon fuels (natural gas, methane, etc.) and oxygen gas in the air. It is attracting attention as a pollution-free power generator that can directly convert chemical energy into electrical energy with high efficiency.

Such a fuel cell is composed of a pair of electrode films (anode electrode and cathode electrode) carrying a catalyst and a proton conductive solid polymer electrolyte membrane sandwiched between the electrode films. Hydrogen ions and electrons are generated at the anode electrode, and the hydrogen ions pass through the solid polymer electrolyte membrane and react with oxygen at the cathode electrode to generate water.

Examples of the solid polymer electrolyte membrane include Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Kogyo Co., Ltd.), and Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.). Commercially available fluorocarbon polymer electrolyte membranes having sulfonic acid groups; mainly aromatic rings such as polyaromatic hydrocarbons, polyether ether ketones, polyphenylene sulfides, polyimides or polybenzazoles A polymer electrolyte membrane having a chain skeleton and having a sulfonic acid group is used.

By the way, in such a fuel cell, there is a concern that hydrogen peroxide or peroxide radicals generated by oxygen reduction reaction may cause deterioration of the solid polymer electrolyte membrane. In recent years, as a factor for lowering the long-term stability of the fuel cell, a part of platinum in the catalyst layer is precipitated in the polymer electrolyte membrane during the operation of the fuel cell, and hydrogen peroxide is formed in the vicinity of the deposited platinum. Has been reported to occur easily (Non-patent Document 1). It is also reported in this document that degradation of the polymer electrolyte membrane is promoted by such hydrogen peroxide.

In order to solve such problems, a polymer electrolyte membrane comprising an ion exchange membrane made of a polymer compound having a sulfonic acid group and a polyphenylene sulfide resin (Patent Document 1), a polymer electrolyte and a high platinum affinity A polymer electrolyte membrane containing a compound (Patent Document 2) and a polymer electrolyte membrane containing a polymer electrolyte and a specific sulfur-containing heterocyclic aromatic compound (Patent Document 3) have been proposed.

JP 2008-235265 A JP 2009-227979 A JP 2012-046741 A

However, the polymer electrolyte membrane described in Patent Document 1 may be inferior in film forming property because the polyphenylene sulfide resin has poor solubility in an organic solvent.
Further, in the polymer electrolyte membranes described in Patent Documents 2 and 3, the durability of the electrolyte membrane is reduced due to elution from the electrolyte membrane of a compound having a high platinum affinity or a sulfur-containing heterocyclic aromatic compound, and the battery. There was room for improvement due to concerns about the decline in power generation performance.

An object of the present invention is to provide a composition capable of easily obtaining a polymer electrolyte membrane that is excellent in durability and can suppress a decrease in power generation performance and water electrolysis performance over time.

Under such circumstances, the present inventors have intensively studied to solve the above problems, and as a result, a polymer having an arylene sulfide skeleton and a polymer soluble in an organic solvent together with a polymer having an ion exchange group. According to the electrolyte membrane composition containing the present invention, the inventors have found that the above object can be achieved, and have completed the present invention.
The configuration of the present invention is as follows.

[1] An electrolyte membrane composition comprising a polymer (A) having an ion exchange group and a polymer (B) having an arylene sulfide skeleton and soluble in an organic solvent.

[2] The electrolyte membrane composition according to [1], wherein the polymer (B) does not have crystallinity.

[3] The electrolyte membrane composition according to [1] or [2], wherein the polymer (B) includes at least one of structural units represented by the following formula (1) or (2).

[In Formula (1), R ¹ and R ² are each independently an alkyl group having 1 to 5 carbon atoms, an alkylsulfanyl group having 1 to 5 carbon atoms, a cyano group or a halogen atom, and a and b are each Independently, it is an integer of 0 to 3. X ¹ and X ² are each independently a direct bond, —S—, —NH—, —SO— or —SO ₂ —, but at least one of X ¹ and X ² is —S—. ]

[In the formula (2), R ³ represents an alkyl group having 1 to 5 carbon atoms, an alkylsulfanyl group having 1 to 5 carbon atoms, a cyano group, or a halogen atom, and c represents an integer of 0 to 4. ]

[4] The electrolyte membrane composition according to any one of [1] to [3], wherein the polymer (B) includes at least one of structural units represented by the following formulas (3) to (5): object.

Wherein ^{(3), R 1, R} 2, X 1, X 2, a and b are each independently, R ¹ in the formula ^{^{(1), R 2, X 1, X}} 2, a and b Is synonymous with ]

[In the formulas (4) and (5), R ³ and c are each independently synonymous with R ³ and c in the formula (2). ]

[5] The electrolyte according to any one of [1] to [4], wherein the polymer (B) has at least one group selected from the group consisting of a polar group, a group containing a fluorine atom, and a fluorenylidene group. Film composition.

[6] The electrolyte membrane composition according to any one of [1] to [5], wherein the polymer (B) has a structural unit represented by the following formula (7).

[In the formula (7), D is independently a direct bond, —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) ₁ — (l is 1 to 10 -C (CF ₃ ) ₂ -,-(CH ₂ ) _l- (l is an integer of 1 to 10), -C (CR ' ₃ ) _2- (R' is independently A cyclohexylidene group, a fluorenylidene group, —O— or —S—, and A and E are each independently a direct bond, —O— or —S—. R ⁴ to R ¹¹ are each independently a hydrogen atom, a fluorine atom, an alkyl group, an allyl group, an aryl group, a halogenated alkyl group in which some or all of the hydrogen atoms are halogenated, a nitro group, or a cyano group. And r is an integer of 0-4. However, the structural unit represented by Formula (7) is not the structural unit represented by Formula (2). ]

[7] The electrolyte membrane composition according to any one of [1] to [6], wherein the polymer (B) has a number average molecular weight in the range of 1,000 to 10,000.

[8] The electrolyte membrane composition according to any one of [1] to [7], further comprising at least one metal component selected from the group consisting of metal-containing compounds and metal ions.

[9] A solid polymer electrolyte membrane obtained from the electrolyte membrane composition according to any one of [1] to [8].

[10] A platinum surface having a surface area of 0.785 mm ² is immersed in an aqueous solution obtained by immersing the electrolyte membrane (volume 0.036 cm ³ ) in 50 mL of 1N sulfuric acid aqueous solution at 80 ° C. for 100 hours and then removing the electrolyte membrane. The poisoning rate of platinum is 20% or less when immersed in 20 cycles of cyclic voltammetry at a sweep rate of 0.01 V / s and a sweep potential range of 0.05 to 0.4 V. 9]. The solid polymer electrolyte membrane according to [9].

[11] The solid polymer according to [9] or [10], wherein the polymer (B) is present at least within 30% of the thickness of the electrolyte membrane relative to the thickness of the electrolyte membrane. Electrolyte membrane.

[12] The method for producing a solid polymer electrolyte membrane according to any one of [9] to [11], comprising a step of applying the electrolyte membrane composition according to any one of [1] to [8].

[13] A membrane-electrode assembly in which a gas diffusion layer, a catalyst layer, the solid polymer electrolyte membrane according to any one of [9] to [11], a catalyst layer, and a gas diffusion layer are laminated in this order.
[14] A polymer electrolyte fuel cell having the membrane-electrode assembly according to [13].

[15] A water electrolysis cell in which a catalyst layer, the solid polymer electrolyte membrane according to any one of [9] to [11], and a catalyst layer are laminated in this order.
[16] A water electrolysis apparatus having the water electrolysis cell according to [15].

According to the present invention, it is possible to easily obtain a polymer electrolyte membrane that is excellent in durability and can suppress a decrease in power generation performance and water electrolysis performance over time.

≪Composition for electrolyte membrane≫
The composition for electrolyte membrane of this invention contains the polymer (A) which has an ion exchange group, and the polymer (B) which has an arylene sulfide skeleton and is soluble in an organic solvent.
According to such a composition, it is possible to easily obtain a polymer electrolyte membrane that is excellent in durability and that can suppress a decrease in power generation performance and water electrolysis performance over time.

The composition for an electrolyte membrane of the present invention is preferably a liquid composition from the viewpoint of ease of production of a solid polymer electrolyte membrane (hereinafter also simply referred to as “electrolyte membrane”).

<Polymer having ion exchange group (A)>
The polymer (A) having an ion exchange group is not particularly limited as long as it is a polymer having an ion exchange group, and may be one used for a conventional solid polymer electrolyte membrane.
As an ion exchange group, a well-known thing can be used, Although it does not specifically limit, A phosphonic acid group, a sulfonic acid group, etc. are mentioned.
Among these, by using a polymer having a sulfonic acid group, an electrolyte membrane excellent in power generation performance and water electrolysis performance can be obtained.
The said polymer (A) may be used individually by 1 type, and may use 2 or more types together.

Examples of such a polymer (A) include polyacetal, polyethylene, polypropylene, acrylic resin, polystyrene, polystyrene-graft-ethylenetetrafluoroethylene copolymer, polystyrene-graft-polytetrafluoroethylene, and aliphatic polycarbonate. Polymers in which sulfonic acid groups are introduced into aliphatic polymers (aliphatic polymers having sulfonic acid groups), polyesters, polysulfones, polyphenylene ethers, polyether imides, aromatic polycarbonates, polyether ether ketones, poly Ether ketone, polyether ketone ketone, polyether ether sulfone, polyether sulfone, polycarbonate, polyphenylene sulfide, aromatic polyamide, aromatic polyamideimide, aromatic polyimide , A polymer in which a sulfonic acid group is introduced into an aromatic polymer having an aromatic ring in part or all of the main chain thereof such as polybenzoxazole, polybenzothiazole, polybenzimidazole, etc. (aromatic having a sulfonic acid group System polymer).
Moreover, the polymer which replaced the group introduce | transduced into these polymers with ion-exchange groups, such as a phosphonic acid group from a sulfonic acid group, or the polymer which used these groups together is mentioned.

As the polymer (A), a known polymer can be used, and is not limited to, but is not limited to a total fluorocarbon polymer having a sulfonic acid group commercially available under a trade name such as Nafion, Aciplex or Flemion, JP 2012-067216, JP 2010-238374, JP 2010-174179, JP 2010-135282, JP 2004-137444, JP 2004-345997, JP 2004. -346163, International Publication No. 2011/155528, Japanese Patent Application Laid-Open No. 2007-177197, International Publication No. 2007/043274, and the like.

Specifically, the polymer (A) is a polymer comprising a hydrophilic segment (A1) serving as a structural unit having a proton conductive group and a hydrophobic segment (B1) serving as a hydrophobic structural unit. It is preferable. In this case, the polymer (A) may be a block polymer or a random polymer, but an electrolyte membrane that is more excellent in power generation, water electrolysis performance, and dimensional stability during a wet and dry cycle is obtained. From the viewpoint of being obtained, a block copolymer of the hydrophilic segment (A1) and the hydrophobic segment (A2) is preferable.

・ Hydrophilic segment (A1)
The hydrophilic segment (A1) is not particularly limited as long as it has a proton conductive group and exhibits hydrophilicity. For example, the hydrophilic segment (A1) has an aromatic ring in the main chain and a proton conductive group such as a sulfonic acid group. From the point that an electrolyte membrane having high continuity of the hydrophilic segment and high proton conductivity can be obtained (hereinafter referred to as “structural unit”). (9) ") is preferable, and a segment composed of the structural unit (9) is more preferable.
The hydrophilic segment (A1) may consist of only one type of structural unit or may contain two or more types of structural units.

In the formula (9), Ar ¹¹ , Ar ¹² and Ar ¹³ are each independently a halogen atom, a nitrile group, a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent halogenated carbon atom having 1 to 20 carbon atoms. An aromatic group having a benzene ring, a condensed aromatic ring or a nitrogen-containing heterocyclic ring which may be substituted with a hydrogen group, and Y and Z are each independently a direct bond, —O—, —S—, —CO —, —SO ₂ —, —SO—, — (CH ₂ ) _u —, — (CF ₂ ) _u — (u is an integer of 1 to 10), —C (CH ₃ ) ₂ — or —C (CF ₃ ) ₂ — and R ¹⁷ is independently a direct bond, —O (CH ₂ ) _p —, —O (CF ₂ ) _p —, — (CH ₂ ) _p — or — (CF ₂ ) _p. -(P represents an integer of 1 to 12), and R ¹⁸ and R ¹⁹ each independently represents a hydrogen atom or a protecting group. However, at least one of all R ¹⁸ and R ¹⁹ contained in the structural unit (9) is a hydrogen atom.
x ¹ independently represents an integer of 0 to 6, x ² represents an integer of 1 to 7, a represents 0 or 1, and b represents an integer of 0 to 20.

The protecting group refers to an ion, atom or atomic group used for the purpose of temporarily protecting a reactive group (—SO ₃ — or —SO ₃ ⁻ ). Specific examples include an alkali metal atom, an aliphatic hydrocarbon group, an alicyclic group, an oxygen-containing heterocyclic group, and a nitrogen-containing cation.

The hydrophilic segment (A1) includes, in addition to the structural unit (9) having a sulfonic acid group, as a structural unit having a proton conductive group other than the sulfonic acid group, for example, a structural unit having a phosphonic acid group, Aromatic structural units having a nitrogen-containing heterocyclic ring described in Kaikai 2011-089036 and International Publication No. 2007/010731 may be included.

・ Hydrophobic segment (A2)
The hydrophobic segment (A2) is not particularly limited as long as it is a hydrophobic segment.
The hydrophilic segment (A2) may consist of only one type of structural unit or may contain two or more types of structural units.

The hydrophobic segment (A2) is preferably a hydrophobic segment having an aromatic ring in the main chain and not containing a proton conductive group such as a sulfonic acid group, and an electrolyte membrane that is more excellent in suppressing hot water swelling. From the viewpoint of being obtained, a structural unit represented by the following formula (10) (hereinafter also referred to as “structural unit (10)”), a structural unit represented by the following formula (11) (hereinafter referred to as “structural unit (11)”. And a segment containing at least one structural unit selected from the group consisting of structural units represented by the following formula (12) (hereinafter also referred to as “structural unit (12)”). Preferably, it is a segment composed of at least one structural unit selected from the group consisting of the structural unit (10) and the structural unit (11).

When the polymer (A) contains any one of the structural units (10) to (12), in particular, the structural unit (10) or (11), the hydrophobicity of the polymer is remarkably improved. Therefore, it is possible to obtain an electrolyte membrane having excellent hot water resistance while having proton conductivity similar to the conventional one. Moreover, when segment (A2) contains a nitrile group, an electrolyte membrane having high toughness and mechanical strength can be produced.

・ Structural unit (10)
By including the structural unit (10), the hydrophobic segment (A2) includes the polymer (10) obtained by increasing the rigidity of the segment (A2) and increasing the aromatic ring density. The hot water resistance, radical resistance to peroxide, gas barrier properties, mechanical strength, dimensional stability, etc. of the electrolyte membrane can be improved.
The hydrophobic segment (A2) may include one type of structural unit (10), or may include two or more types of structural units (10).

In the formula (10), at least one substitutable carbon atom constituting the aromatic ring may be replaced with a nitrogen atom, and R ²¹ is independently a halogen atom, a hydroxy group, a nitro group, a nitrile group or R ²² —. L- (L is a direct bond, —O—, —S—, —CO—, —SO ₂ —, —CONH—, —COO—, —CF ₂ —, —CH ₂ —, —C (CF ₃ ) ₂ -or -C (CH ₃ ) _2- ; R ²² represents an alkyl group, a halogenated alkyl group, an alkenyl group, an aryl group, a halogenated aryl group or a nitrogen-containing heterocyclic ring, and at least one of these groups one of the hydrogen atoms, further hydroxy group, a nitro group, may be substituted with at least one group selected from nitrile group and a group consisting of R ²² -L-.) shows a plurality of R ²¹ is bonded To form a ring structure.
When R ²¹ is R ²² -L-, and R ²² is further substituted with R ²² -L-, the plurality of L may be the same or different, and a plurality of R ²² (provided that The structure of the portion excluding the structural difference caused by the substitution may be the same or different. The same applies to the symbols in the other equations.
c ¹ and c ² independently represent an integer of 0 or 1 or more, d represents an integer of 1 or more, and e independently represents an integer of 0 to (2c ¹ + 2c ² +4).

・ Structural unit (11)
It is preferable that the hydrophobic segment (A2) contains the structural unit (11) because radical resistance to peroxide and the like is improved, and an electrolyte membrane excellent in power generation / water electrolysis durability can be obtained.
Further, when the hydrophobic segment (A2) contains the structural unit (11), an appropriate flexibility (flexibility) can be imparted to the segment (A2), and the electrolyte membrane containing the resulting polymer Toughness can be improved.
The hydrophobic segment (A2) may include one type of structural unit (11), or may include two or more types of structural units (11).

In the formula (11), at least one substitutable carbon atom constituting the aromatic ring may be replaced with a nitrogen atom, and R ³¹ is independently a halogen atom, a hydroxy group, a nitro group, a nitrile group or R ²² —. L— (L and R ²² are each independently synonymous with L and R ²² in the formula (1)), and a plurality of R ³¹ may be bonded to form a ring structure.
f represents 0 or an integer of 1 or more, and g represents an integer of 0 to (2f + 4). However, the structural unit represented by Formula (11) is a structural unit other than the structural unit represented by Formula (10).

・ Structural unit (12)
When the hydrophobic segment (A2) contains the structural unit (12), the segment (A2) can be imparted with appropriate flexibility (flexibility), and the toughness of the electrolyte membrane containing the resulting polymer Can be improved.
The hydrophobic segment (A2) may include one type of structural unit (12) or may include two or more types of structural units (12).

In the formula (12), G and J are each independently a direct bond, —O—, —S—, —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ _I − (i is an integer of 1 to 10), — (CH ₂ ) _j — (j is an integer of 1 to 10), —CR ′ ₂ — (R ′ is an aliphatic hydrocarbon group, aromatic A hydrocarbon group or a halogenated hydrocarbon group.), A cyclohexylidene group or a fluorenylidene group, Q independently represents an oxygen atom or a sulfur atom, and R ¹ to R ¹⁶ each independently represents a hydrogen atom. , halogen atom, hydroxy group, nitro group, nitrile group or R ^22-L-(L and R ²² are independently the same as L and R ²² in formula (10).) indicates, R ¹ ~ A plurality of groups of R ¹⁶ may be bonded to form a ring structure.
s and t each independently represent an integer of 0 to 4, and r represents 0 or an integer of 1 or more.

Synthetic method of polymer (A) The polymer (A) can be synthesized by a conventionally known method, and is not particularly limited. For example, the compound serving as the structural unit is reacted in the presence of a catalyst or a solvent. Then, if necessary, it can be synthesized by introducing a proton conductive group by a method such as conversion of a sulfonic acid ester group or the like to a sulfonic acid group, or sulfonation using a sulfonating agent.

<Physical properties of polymer (A)>
The polystyrene equivalent weight average molecular weight (Mw) of the polymer (A) by gel permeation chromatography (GPC) is preferably 10,000 to 1,000,000, more preferably 20,000 to 800,000, and even more preferably 50,000 to 300,000.

The ion exchange capacity of the polymer (A) is preferably 0.5 to 3.5 meq / g, more preferably 0.5 to 3.0 meq / g, still more preferably 0.8 to 2.8 meq / g. is there. An ion exchange capacity of 0.5 meq / g or more is preferable because an electrolyte membrane having high proton conductivity and high power generation performance and water electrolysis performance can be obtained. On the other hand, if it is 3.5 meq / g or less, an electrolyte membrane having sufficiently high water resistance can be obtained, which is preferable.
The ion exchange capacity can be measured, for example, by the method described in the examples below.

The ion exchange capacity can be adjusted, for example, by changing the type of each structural unit, the use ratio, the combination, and the amount of ion exchange groups introduced. Therefore, it can be adjusted by changing the charge amount ratio and type of the precursor (monomer / oligomer) that induces the structural unit during polymerization.

In general, when the proportion of the structural unit containing an ion exchange group is increased in the polymer, the ion exchange capacity of the obtained electrolyte membrane is increased and the proton conductivity is increased, but the water resistance tends to be reduced. When the proportion of the structural unit is reduced, the ion exchange capacity of the obtained electrolyte membrane is reduced and the water resistance is increased, but the proton conductivity tends to be lowered.

<Polymer (B)>
The polymer (B) is a polymer having an arylene sulfide skeleton and soluble in an organic solvent.
By using such a polymer (B), it is possible to obtain a composition for an electrolyte membrane in which the polymer (B) is uniformly dispersed, and to the outside of the electrolyte membrane during battery operation or water electrolysis device operation. The elution of the polymer and the deterioration of the electrolyte membrane are suppressed, and an electrolyte membrane excellent in durability can be easily obtained. In addition, it is possible to obtain a polymer electrolyte fuel cell and a water electrolysis device that are excellent in balance between power generation performance, water electrolysis performance, long-term stability, and the like.
The said polymer (B) may be used individually by 1 type, and may use 2 or more types together.

Generally, a catalyst layer is provided on an electrode of a polymer electrolyte fuel cell, and platinum, ruthenium, or the like is used as a catalyst contained in the catalyst layer. These catalysts are important because they promote the chemical reaction that is the source of the extracted electrical energy. On the other hand, during the operation of the battery, a part of the catalyst in the catalyst layer is deposited in the electrolyte membrane. It is believed that the electrolyte membrane is deteriorated by the catalyst, and this is a factor that lowers the long-term stability of the polymer electrolyte fuel cell.

In addition, in water electrolysis cells in water electrolysis devices that generate hydrogen and oxygen by electrolysis of water, platinum, ruthenium, iridium, iron, etc. are used as the catalyst contained in the catalyst layer. As in the case of the fuel cell, a part of the catalyst in the catalyst layer is deposited in the electrolyte membrane during the operation of the water electrolysis device, and this deposited catalyst causes deterioration of the electrolyte membrane, and the long-term stability of the water electrolysis device. Is considered to be a factor that reduces In particular, the deposited platinum and iron may cause significant deterioration of the electrolyte membrane.

From the above, the present inventors inactivate a catalyst such as platinum in the vicinity of the interface between the electrolyte membrane and the electrode, while being located away from the interface between the electrolyte membrane and the electrode, Catalysts such as platinum, which are thought to have little impact on the battery, are not deactivated, so that the polymer electrolyte fuel cell has a good balance between power generation performance and long-term stability, and water electrolysis performance and long-term stability. We thought that an excellent water electrolysis apparatus with good balance could be obtained.

As a result of intensive studies, the present inventors have used an electrolyte membrane containing the polymer (B) together with the polymer (A) having an ion exchange group, so that the solid state excellent in balance between power generation performance and long-term stability can be obtained. It has been found that a molecular fuel cell and a water electrolysis device excellent in balance between water electrolysis performance and long-term stability can be obtained.

Since the polymer (B) has an arylene sulfide skeleton and is soluble in an organic solvent, the electrolyte membrane containing the polymer (B) has a specific poisoning rate of platinum. It becomes as follows. This means that the elution amount of the polymer (B) from the electrolyte membrane is below a certain range. This inactivates platinum in the vicinity of the interface between the electrolyte membrane and the electrode, while deactivating platinum, which is located far from the interface between the electrolyte membrane and the electrode and has little effect on the deterioration of the electrolyte membrane. It is not considered to be converted.
Therefore, when the composition for electrolyte membrane of the present invention contains the polymer (B), a polymer electrolyte fuel cell excellent in balance between power generation performance and long-term stability, and water electrolysis performance and long-term stability. It is possible to obtain a water electrolysis apparatus excellent in balance.

The polymer (B) has an arylene sulfide skeleton. The polymer (B) has an arylene sulfide skeleton, so that the polymer (B) has excellent compatibility with the polymer (A), and the elution to the outside of the electrolyte membrane during battery power generation or water electrolysis is suppressed. Tend to be.
In the present invention, the arylene sulfide skeleton refers to a structural unit in which a sulfide bond (—S—) is bonded to a monocyclic or polycyclic aromatic hydrocarbon group, for example, a heavy unit having a thianthrene structure. The polymer is also referred to as a polymer having an arylene sulfide skeleton because it has a portion in which a sulfide bond is bonded to a benzene ring.
In this skeleton, the sulfide bond portion is easily coordinated to platinum. For this reason, it is thought that this sulfide bond part contributes to inactivation of platinum.

The polymer (B) becomes a polymer having excellent compatibility with the polymer (A), and becomes a polymer in which elution to the outside of the electrolyte membrane during battery power generation or water decomposition is suppressed. Preferably, at least one of the structural units represented by the following formula (1) or (2) (hereinafter also referred to as “structural unit (1)” and “structural unit (2)”) is included.

In the formula (1), R ¹ and R ² are each independently an alkyl group having 1 to 5 carbon atoms, an alkylsulfanyl group having 1 to 5 carbon atoms, a cyano group, or a halogen atom, and a and b are each Independently, it is an integer of 0 to 3. X ¹ and X ² are each independently a direct bond, —S—, —NH—, —SO— or —SO ₂ —, but at least one of X ¹ and X ² is —S—.

R ¹ and R ² are preferably a cyano group or a halogen atom from the viewpoint of improving the solubility in a polar solvent.
Said a and b are preferably 0 or 1, more preferably 0.

At least one of X ¹ and X ² is —S—, and the other is preferably a single bond or —S— from the viewpoint of becoming a polymer having a high sulfur content, and is an organic solvent. From the viewpoints of obtaining a polymer excellent in solubility in water and obtaining an electrolyte membrane that can sufficiently inactivate platinum in the vicinity of the interface between the electrolyte membrane and the electrode even if the amount of the polymer (B) added is small. More preferably, it is —S—.

In the formula (2), R ³ is an alkyl group having 1 to 5 carbon atoms, an alkylsulfanyl group having 1 to 5 carbon atoms, a cyano group or a halogen atom, and c is an integer of 0 to 4.

R ³ is preferably a cyano group, a chlorine atom, a bromine atom, or an iodine atom from the viewpoint of improving the solubility in a polar solvent.
The c is preferably 0 or 1, more preferably 0.

The polymer (B) can obtain a composition for an electrolyte membrane in which the polymer (B) is uniformly dispersed, and is a solid polymer fuel excellent in balance in power generation performance, water electrolysis performance, long-term stability, etc. It is preferable that at least one of the structural units represented by the following formulas (3) to (5) is included from the viewpoint that a battery or a water electrolysis device can be obtained.

When the polymer (B) contains the structural unit (2), a polymer having better solubility in an organic solvent is obtained, and an electrolyte membrane composition in which the polymer (B) is uniformly dispersed is obtained. Among the structural units represented by the formulas (4) and (5), it is preferable that the structural unit represented by the formula (5) is included in the structural units represented by the formula (5). It is more preferable that the structural unit and the structural unit represented by the following formula (2 ′) are included.

In formula (2 '), R ³ and c are independently the same meanings as R ³ and c in the formula (2). ]

As the polymer (B), a polymer excellent in compatibility with the polymer (A) or an organic solvent can be obtained, and a composition for an electrolyte membrane in which the polymer (B) is uniformly dispersed can be obtained. It is preferable to have a structural unit represented by the following formula (6) from the viewpoint of obtaining a polymer electrolyte fuel cell and a water electrolysis device that are excellent in performance, water electrolysis performance, long-term stability and the like. .

Wherein ^{(6), R 1, R} 2, X 1, X 2, a and b are each independently, R ¹ in the formula ^{^{(1), R 2, X 1, X}} 2, a and b X ³ is —O— or —S—. ]

In addition, the polymer (B) has at least one group selected from the group consisting of a polar group, a group containing a fluorine atom and a fluorenylidene group, so that a polymer excellent in solubility in a polar solvent can be obtained. From the point of view, it is preferable.
These groups are not particularly limited as long as they are contained in the polymer (B), but may be contained in any one of the groups represented by the above or the following formulas (1) to (8). preferable.

Examples of the polar group include a cyano group, a hydroxy group, and a carboxy group.
Examples of the group containing a fluorine atom include —CF ₃ , —C (CF ₃ ) ₂ — and the like.

The polymer (B) preferably has a structural unit represented by the following formula (7) from the viewpoint of obtaining a polymer excellent in solubility in an organic solvent, and the structural unit (1) and In addition to the structural unit (2), it is more preferable to further have a structural unit represented by the following formula (7).

[In the formula (7), D is independently a direct bond, —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) ₁ — (l is 1 to 10 -C (CF ₃ ) ₂ -,-(CH ₂ ) _l- (l is an integer of 1 to 10), -C (CR ' ₃ ) _2- (R' is independently A cyclohexylidene group, a fluorenylidene group, —O— or —S—, and A and E are each independently a direct bond, —O— or —S—. R ⁴ to R ¹¹ are each independently a hydrogen atom, a fluorine atom, an alkyl group, an allyl group, an aryl group, a halogenated alkyl group in which some or all of the hydrogen atoms are halogenated, a nitro group, or a cyano group. And r is an integer of 0-4. However, the structural unit represented by Formula (7) is not the structural unit (2). ]

The hydrocarbon group for R ′ is preferably a linear or branched alkyl group having 1 to 12 carbon atoms, more preferably a linear or branched alkyl group having 1 to 8 carbon atoms, and 1 to 5 carbon atoms. The linear or branched alkyl group is more preferable.
Preferable specific examples of the hydrocarbon group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group. And n-heptyl group.

Examples of the cyclic hydrocarbon group for R ′ include an alicyclic hydrocarbon group and an aromatic hydrocarbon group.
The alicyclic hydrocarbon group is preferably an alicyclic hydrocarbon group having 3 to 12 carbon atoms, specifically, a cycloalkyl group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group; And cycloalkenyl groups such as cyclobutenyl group, cyclopentenyl group, and cyclohexenyl group.
The aromatic hydrocarbon group is preferably an aromatic hydrocarbon group having 6 to 12 carbon atoms, and specific examples include a phenyl group, a biphenyl group, and a naphthyl group.

The alkyl group in R ⁴ to R ¹¹ is preferably a group exemplified as a preferred example of the hydrocarbon group in R ′. The halogenated alkyl group for R ⁴ to R ¹¹ is preferably a group obtained by halogenating some or all of the alkyl groups.
The aryl group in R ⁴ to R ¹¹ is preferably a group listed as a preferred example of the aromatic hydrocarbon group.

D is preferably —S—, —O—, —C (CF ₃ ) ₂ — or a fluorenylidene group from the viewpoint of obtaining a polymer having excellent solubility in a polar solvent.
A and E are preferably —O— or —S— from the viewpoint of improving the solubility of the polymer (B).
R ⁴ to R ¹¹ are each a hydrogen atom, a fluorine atom, a halogenated alkyl group in which some or all of the hydrogen atoms are halogenated from the viewpoint of obtaining a polymer excellent in solubility in a polar solvent, A nitro group or a cyano group is preferred.

When the polymer (B) includes the structural unit (1), the polymer (B) has a structural unit represented by the following formula (8), which is superior in solubility in an organic solvent and has a high sulfur content. Is preferable from the viewpoint of obtaining

Wherein ^{(8), R 1, R} 2, X 1, X 2, a and b are each independently, R ¹ in the formula ^{^{(1), R 2, X 1, X}} 2, a and b in the above ^{formula, D, E, R 4 ~} R 11 and r are as defined above D in the formula ^{(7), E, R 4} ~ R 11 and r, a 'is -O- or -S- It is. ]

<Synthesis Method of Polymer (B)>
The method for synthesizing the polymer (B) is not particularly limited, and can be synthesized by a conventionally known method. For example, a method for polymerizing a monomer having an arylene sulfide skeleton, a sulfide bond when synthesizing a polymer, and the like. And a method of polymerizing so that the resulting polymer has an arylene sulfide skeleton.

The polymer (B) includes, for example, a dihydroxy compound containing a dihalide containing the structural unit (1) and a structural unit represented by the formula (7) (where A and E are direct bonds). Can be obtained by polymerizing by heating in an appropriate organic solvent in the presence of an alkali metal compound such as potassium carbonate, and the structural unit represented by the formula (7) (where A and E are The dihalogen compound containing a direct bond) and an alkali metal sulfide salt such as sodium sulfide are heated and polymerized in a suitable organic solvent.
Specific examples include the methods shown in Synthesis Examples 3 to 7 below.

In the synthesis of the polymer (B), the amount of the dihalide containing the structural unit (1) and the monomer that can become the post-polymerization structural unit (2) are the solubility in an organic solvent and the deterioration of the electrolyte membrane. From the viewpoint of the balance with the inhibitory effect, it is preferably 10 to 70 mol%, more preferably 20 to 60 mol%, based on 100 mol% of all monomers used for the synthesis of the polymer (B).

<Physical properties of polymer (B)>
The number average molecular weight of the polymer (B) is preferably 1000 or more, more preferably 1100 or more, and further preferably 1200 or more. Further, the upper limit of the number average molecular weight of the polymer (B) is preferably 10,000 or less, more preferably 9000 or less, and further preferably 8000 or less.
When the number average molecular weight of the polymer (B) is less than 1000, the amount of the polymer (B) eluted out of the electrolyte membrane during battery power generation or water decomposition may be excessively increased. In addition, when the number average molecular weight of the polymer (B) exceeds 10,000, the solubility of the polymer (B) in an organic solvent described later decreases, or the compatibility (dispersibility) of the polymer (A) decreases. Sometimes.
In addition, the molecular weight of the said polymer (B) can be measured by the method as described in a following example.

The polymer (B) preferably has a sulfur atom content constituting a sulfide bond in the polymer of 2.0 mmol / g or more. More preferably, it is 2.5 mmol / g or more, More preferably, it is 2.7 mmol / g or more. When the content of sulfur atoms constituting the sulfide bond in the polymer (B) is less than 2.0 mmol / g, the effect of suppressing deterioration of the electrolyte membrane during battery power generation or water decomposition may not be sufficient.
The polymer (B) preferably has a sulfur atom content constituting a sulfide bond in the polymer of 10.0 mmol / g or less.
Content of the sulfur atom which comprises the sulfide bond in such a polymer (B) can be quantified by a Raman spectroscopy, for example.

The polymer (B) is a polymer soluble in an organic solvent. Here, the “polymer soluble in an organic solvent” is preferably a polymer that is soluble in 10 g or more in 1 L of an organic solvent, and more preferably a polymer that is soluble in 20 g or more. Examples of the organic solvent can be exemplified as follows. Particularly, a polymer that can be dissolved in an amount of 10 g or more in 1 L of a mixed solvent of N-methyl-2-pyrrolidone (hereinafter NMP) / methyl ethyl ketone / methanol = 60/20/20 (mass ratio). It is preferable that the polymer is soluble in 20 g or more.
Since the polymer (B) is soluble in an organic solvent, it is possible to produce an electrolyte membrane by a simple production method and the compatibility (dispersibility) with the polymer (A) is good. preferable.

The organic solvent is not particularly limited, but for example, aprotic systems such as NMP, N, N-dimethylformamide, γ-butyrolactone, N, N-dimethylacetamide, dimethyl sulfoxide, dimethylurea, dimethylimidazolidinone, and acetonitrile. Polar solvents, chlorinated solvents such as dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene, dichlorobenzene, alcohols such as methanol, ethanol, propanol, iso-propyl alcohol, sec-butyl alcohol, tert-butyl alcohol, ethylene glycol Alkylene glycol monoalkyl ethers such as monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, acetone, methyl ethyl Tons, ketones such as cyclohexanone, tetrahydrofuran, ethers 1,3-dioxane and the like.

Moreover, it is preferable that the said polymer (B) is a polymer which does not have crystallinity from the point that the polymer excellent in the solubility to an organic solvent is obtained.
Whether or not the polymer has crystallinity can be determined, for example, by the presence or absence of a melting peak in DSC measurement.

The melting point of the polymer (B) measured by Yanagimoto Seisakusho, precision melting point measuring device (model number: MP-500D) is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, and still more preferably 120. ℃ or more. When the melting point of the polymer (B) is less than 80 ° C., the polymer (B) is likely to move in the electrolyte membrane while the battery or water electrolysis apparatus is operating at a high temperature, and is easily eluted out of the electrolyte membrane. Therefore, durability of the electrolyte membrane, power generation performance, and water electrolysis performance tend to decrease.

The polymer (B) has a mass ratio of the polymer (A) to the polymer (B) of 99.99: 0.01 to 70:30, preferably 99.95: 0.05 to 75. : 25, more preferably 99.9: 0.1 to 80:20, particularly preferably 99.5: 0.5 to 85:15 in an amount of 99.5: 0.5 to 85:15. . When the polymer (A) and the polymer (B) are contained in such a range, an electrolyte membrane exhibiting good durability and proton conductivity can be obtained.

<Metal component>
The electrolyte membrane composition of the present invention may further contain at least one metal component selected from the group consisting of a metal-containing compound and a metal ion in addition to the polymer (A) and the polymer (B).

As the metal component, a component having hydrogen peroxide decomposability is preferable. Specifically, hydrogen peroxide that can be generated during battery power generation or water decomposition is converted into water by using a redox reaction or a disproportionation reaction. A component having capacity is more preferred.

Examples of the metal component include tin (Sn), aluminum (Al), manganese (Mn), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), and nickel (Ni). , Palladium (Pd), silver (Ag), cerium (Ce), vanadium (V), neodymium (Nd), praseodymium (Pr), samarium (Sm), cobalt (Co), gadolinium (Gd), terbium (Tb) And metal-containing compounds such as dysprosium (Dy), holmium (Ho) and erbium (Er), or metal ions thereof.

As the metal-containing compound, oxides of these metals are preferable.
Moreover, as said metal component, a tin oxide and a tin ion are preferable, and the electrolyte membrane excellent in durability is obtained by using the composition containing these.

The compounding amount of the metal component is not particularly limited, but is preferably 0.01 to 30% by weight, more preferably 0.1 to 25% by weight with respect to 100% by weight of the electrolyte membrane composition of the present invention. More preferably, it is 1 to 20% by weight.

<Solvent>
The electrolyte membrane composition according to the present invention preferably further contains a solvent. A liquid composition can be obtained because the composition for electrolyte membrane of this invention contains the said solvent.

Although it does not restrict | limit especially as said solvent, It is preferable that it is a solvent which can melt | dissolve said polymer (A) and said polymer (B), Specifically, the said organic solvent etc. are mentioned. These solvents can be used alone or in combination of two or more.
In particular, NMP is preferable from the viewpoint of the solubility of the polymer (A) and the polymer (B) and the viscosity of the composition.

Further, when a mixture of an aprotic polar solvent and another solvent is used as the solvent, the composition of the mixture is preferably 25 to 95% by mass, more preferably 25 to 90% by mass of the aprotic polar solvent. %, And the other solvent is preferably 5 to 75% by mass, more preferably 10 to 75% by mass (provided that the total is 100% by mass). When the blending amount of the other solvent is within the above range, the effect of reducing the viscosity of the resulting composition is excellent. As a combination of the aprotic polar solvent and the other solvent in this case, NMP is preferable as the aprotic polar solvent, and methanol or methyl ethyl ketone is effective as the other solvent in reducing the viscosity of the composition in a wide composition range.

The content of the polymer (A) in the liquid composition is preferably 1 to 40% by mass, more preferably 3 to 25% by mass, although it depends on the molecular weight of the polymer. When the content of the polymer (A) is less than 1% by mass, the obtained electrolyte membrane tends to cause poor appearance and tends to generate pinholes. On the other hand, when the content of the polymer (A) exceeds 40% by mass, the viscosity of the composition may be too high to form a film from the composition, and the obtained electrolyte film may have surface smoothness. May be lacking.

The viscosity of the liquid composition is preferably 2,000 to 100,000 mPa · s, more preferably 3,000 to 50, although it depends on the molecular weight and concentration of the polymers (A) and (B). 1,000 mPa · s.
When the viscosity of the liquid composition is within the above range, it is preferable because the composition has excellent retention during film formation, the thickness can be easily adjusted, and the film can be easily formed by a casting method.

The liquid composition can be prepared by mixing the polymer (A) and the polymer (B) in the solvent. Specifically, a method of simultaneously dissolving or dispersing the polymers (A) and (B) in the solvent, and after dissolving or dispersing the polymer (A) in the solvent, the polymer (B) Examples thereof include a method of preparing by mixing with this, or a method of dissolving or dispersing the polymer (A) after dissolving the polymer (B) in the solvent.

In the composition for electrolyte membrane, in addition to the polymer (A), the polymer (B) and a solvent blended as necessary, inorganic acids such as sulfuric acid and phosphoric acid; phosphate glass; tungstic acid; phosphoric acid Salt hydrate; β-alumina proton substitution product; inorganic proton conductor particles such as proton-introduced oxide; organic acid containing carboxylic acid; organic acid containing sulfonic acid; organic acid containing phosphonic acid; May be.

≪Solid polymer electrolyte membrane≫
The electrolyte membrane of the present invention is not particularly limited as long as it is a membrane obtained from the electrolyte membrane composition, but is preferably a membrane obtained from the liquid composition.
The electrolyte membrane of the present invention can be suitably used as an electrolyte membrane for a polymer electrolyte fuel cell and as an electrolyte membrane for water electrolysis, and particularly preferably used as an electrolyte membrane for a polymer electrolyte fuel cell. it can.

Since the electrolyte membrane of the present invention contains the polymer (A) and the polymer (B), it is difficult to deteriorate during battery power generation, has excellent power generation performance and durability, and when an electrode containing platinum is used, The platinum poisoning rate due to the eluate that can be eluted from the electrolyte membrane is low.
Similarly, it is hardly deteriorated during water electrolysis, is excellent in water electrolysis performance and durability, and when an electrode containing platinum is used, the poisoning rate of platinum due to an eluate that can be eluted from the electrolyte membrane is low.

The electrolyte membrane of the present invention (volume 0.036 cm ³ ) was immersed in 50 mL of 1N sulfuric acid aqueous solution at 80 ° C. for 100 hours, and then the platinum membrane having a surface area of 0.785 mm ² was added to the aqueous solution obtained by removing the electrolyte membrane. Is poisoned when platinum is immersed while measuring 20 cycles of cyclic voltammetry at a sweep rate of 0.01 V / s and a sweep potential range of 0.05 to 0.4 V, preferably 20% or less. More preferably, it is 15% or less. The lower limit of the platinum poisoning rate may be 0%.
When the platinum poisoning rate is in the above range, when an electrode containing platinum is used, the platinum in the vicinity of the interface between the electrolyte membrane and the electrode is inactivated and located at a location away from the interface between the electrolyte membrane and the electrode. Thus, it is possible to obtain a polymer electrolyte fuel cell and a water electrolysis apparatus that are excellent in balance between power generation performance, water electrolysis performance, and long-term stability, which are difficult to inactivate platinum, which is considered to have little influence on the deterioration of the electrolyte membrane.

In the electrolyte membrane of the present invention, the polymer (B) is preferably present at least within 30% of the thickness of the membrane from the surface of the membrane.
Since the polymer (B) usually has low proton conductivity, in order to obtain an electrolyte membrane having high power generation performance and high water electrolysis performance, the content of the polymer (B) contained in the electrolyte membrane is reduced as much as possible. It is considered that it is desired to improve the durability of the electrolyte membrane. In particular, as described above, the polymer (B) only needs to be able to inactivate platinum in the vicinity of the interface between the electrolyte membrane and the electrode. Electrolyte membrane excellent in balance between power generation performance, water electrolysis performance and long-term stability even when the content of the polymer (B) contained in the electrolyte membrane is small because it is located within 30% of the surface of Can be obtained.

Furthermore, even if the content of the polymer (B) contained in the electrolyte membrane is reduced, an electrolyte membrane excellent in balance between power generation performance, water electrolysis performance and long-term stability can be obtained. In the electrolyte membrane, the polymer (B) is preferably unevenly distributed in the vicinity of the surface of the membrane, and may be present only at a position within 30% from the surface of the electrolyte membrane with respect to the thickness of the membrane. More preferred.
When the polymer (B) is unevenly distributed near the surface of the electrolyte membrane, the electrolyte membrane has a concentration gradient such that the concentration of the polymer (B) gradually increases as it approaches the surface of the membrane. It may be.

The electrolyte membrane of the present invention may be a single layer film or a multilayered film.
In the case of a laminated film, the thickness of each layer is arbitrary. For example, one layer may be thick and the other layer may be thin.

From the viewpoint of durability and proton conductivity of the electrolyte membrane, the electrolyte membrane of the present invention contains the polymer (B) on one side or both surfaces in contact with the electrode when the membrane-electrode assembly is produced, The electrolyte membrane which does not contain a polymer (B) in the part other than that may be sufficient.
When the membrane-electrode assembly is prepared, the polymer (B) is contained only in the vicinity of one surface in contact with the electrode, and the other portion does not contain the polymer (B). In order to further suppress deterioration, the electrode is preferably a cathode electrode.

<Method for producing solid polymer electrolyte membrane>
The electrolyte membrane according to the present invention includes, for example, a step of applying the electrolyte membrane composition onto a substrate by a known method such as die coating, spray coating, knife coating, roll coating, spin coating, or gravure coating. Can be manufactured. Specifically, the electrolyte membrane of the present invention can be obtained by applying the electrolyte membrane composition onto a substrate, drying the applied composition, and peeling the resulting film from the substrate, if necessary. it can.
Since the composition for electrolyte membrane of this invention contains a polymer (A) and a polymer (B), an electrolyte membrane can be easily manufactured with the said well-known method.

The substrate is not particularly limited as long as it is a substrate used when a normal solution is applied, and examples thereof include a substrate made of resin, metal, glass, and preferably a polyethylene terephthalate (PET) film. And a base made of a thermoplastic resin.

The drying is preferably performed by holding at a temperature of 50 to 150 ° C. for 0.1 to 10 hours.
Note that the drying may be performed in one step, or may be performed in two or more steps, that is, pre-drying after preliminary drying.
Moreover, you may perform the said drying in inert gas atmosphere, such as nitrogen atmosphere, or under reduced pressure as needed.

The preliminary drying can be performed by holding at 30 to 100 ° C., more preferably 50 to 100 ° C., preferably 10 to 180 minutes, more preferably 15 to 60 minutes.
Further, the main drying can be carried out preferably by holding at a temperature not lower than the preliminary drying temperature, more preferably at a temperature of 50 to 150 ° C., and preferably for 0.1 to 10 hours.

When the obtained dried film is immersed in water after the preliminary drying or after the main drying, the organic solvent in the dried film can be replaced with water, and the residual organic solvent in the obtained electrolyte film The amount can be reduced. The amount of residual organic solvent in the electrolyte membrane thus obtained is preferably 5% by mass or less. Depending on the immersion conditions, the amount of the remaining organic solvent in the obtained film can be 1% by mass or less.
As such conditions, for example, the amount of water used is 50 parts by weight or more with respect to 1 part by weight of the dried film, the temperature of the water during immersion is 10 to 60 ° C., and the immersion time is 10 minutes to 10 hours. It is.

After the dried membrane is immersed in water as described above, it is further dried at 30 to 100 ° C., preferably 50 to 80 ° C. for 10 to 180 minutes, preferably 15 to 60 minutes, and then 50 to 150 ° C. Thus, it is preferable to obtain an electrolyte membrane by vacuum drying under reduced pressure of 500 mmHg to 0.1 mmHg for 0.5 to 24 hours.

As a method for obtaining the laminated film (two layers), the composition (I) is applied onto a substrate by a known method, and after drying or as necessary, a layer is formed, and then the layer is formed. The method of apply | coating composition (II) on top and drying and forming a layer is mentioned. In the case of obtaining a laminated film having three or more layers, another composition may be applied on the obtained layer and dried.
In addition, the composition (I) is applied onto a substrate by a known method and, if necessary, pre-dried, a film previously formed from the composition (II) or the like is placed thereon and subjected to hot pressing or the like. Thus, a laminated film can also be obtained.

The composition (I), the composition (II), and other compositions that can be further used are not particularly limited as long as they can form a layer and do not impair the effects of the present invention. The composition containing (A) or the composition for electrolyte membrane of the present invention is preferred. Among the composition (I), the composition (II), and other compositions that can be further used, at least one composition is the electrolyte membrane composition of the present invention.

The composition (I), composition (II), and other compositions that can be further used differ in the composition (formulation component and / or amount) of the composition forming the adjacent layers. Are preferred, and the composition of the composition forming the non-adjacent layers may be the same or different.

According to such a method, for example, the composition for an electrolyte membrane of the present invention is used as the composition (I), and the polymer (B) includes the polymer (A) as the composition (II). ) -Containing composition, the polymer (B) is easily produced at least at a position within 30% of the thickness of the membrane from the membrane surface or an unevenly distributed electrolyte membrane. be able to.

A reinforced solid polymer electrolyte membrane can also be produced by using a porous substrate or a sheet-like fibrous material.
Examples of the method for producing the reinforced solid polymer electrolyte membrane include a method of impregnating the liquid composition into a porous substrate or a sheet-like fibrous material, and a method for impregnating the electrolyte membrane composition of the present invention with a porous substrate. A method of applying to a material or a sheet-like fibrous material, and after forming a film from the electrolyte membrane composition of the present invention in advance, the membrane is laminated on a porous substrate or a sheet-like fibrous material, and hot pressing The method of doing is mentioned.

The porous substrate preferably has a large number of pores or voids penetrating in the thickness direction. For example, organic porous substrates made of various resins, metal oxides such as glass and alumina And inorganic porous base materials composed of metal and the metal itself.
The porous substrate may have a large number of through holes penetrating in a direction substantially parallel to the thickness direction.

Examples of such a porous substrate include, for example, JP 2008-119662, JP 2007-154153, JP 8-20660, JP 8-20660, JP 2006-120368. For example, those disclosed in Japanese Patent Laid-Open No. 2004-171994 and Japanese Patent Laid-Open No. 2009-64777 can be used.

As the porous substrate, an organic porous substrate is preferable. Specific examples of the porous substrate include polyolefins such as polytetrafluoroethylene, high molecular weight polyethylene, cross-linked polyethylene, polyethylene and polypropylene, polyimide, polyacrylotolyl, polyamideimide, polyetherimide, and polyether. A base material composed of one or more selected from the group consisting of sulfone and glass is preferred. The polyolefin is preferably high molecular weight polyethylene, cross-linked polyethylene, polyethylene or the like.

Examples of commercially available porous base materials include stretched porous polytetrafluoroethylene GORE-SELECT (manufactured by Japan Gore-Tex) and high molecular weight polyethylene porous base materials (manufactured by Lydall, SOLUPOR (registered trademark)). Is mentioned.

The porous base material is preferably a base material made of polyolefin such as polytetrafluoroethylene, high molecular weight polyethylene, cross-linked polyethylene, polyethylene and the like because it contacts the polymer (A). If necessary, the polyolefin substrate may be hydrophilized.

The hydrophilization treatment is a treatment that modifies the polyolefin constituting the porous using an alkali metal solution, and this treatment modifies the surface of the porous substrate and imparts hydrophilicity. Since the denatured portion may be browned, the browned portion may be removed by oxidative decomposition with hydrogen peroxide, sodium hypochlorite, ozone, or the like. Such hydrophilic treatment is sometimes referred to as chemical etching.
Examples of the alkali metal solution include a solution obtained by dissolving methyl lithium, a metal sodium-naphthalene complex, a metal sodium-anthracene complex, and the like in an organic solvent such as tetrahydrofuran, a metal sodium-liquid ammonia solution, and the like.

The porosity and thickness of the porous substrate are not particularly limited as long as the effects of the present invention are not impaired.

Moreover, as a sheet-like fibrous substance, a nonwoven fabric, a woven fabric, a knitted fabric, etc. are mentioned. Examples of the fibers constituting the woven fabric include, but are not limited to, polyethylene fibers, fluoropolymer reinforced fibers, polyimide fibers, polyphenylene sulfide sulfone fibers, polysulfone fibers, and glass fibers.
Examples of the fibers constituting the nonwoven fabric include polyamide resins, polyvinyl alcohol resins, polyvinylidene chloride resins, polyvinyl chloride resins, polyester resins, polyacrylonitrile resins, polyolefin resins (for example, polyethylene resins, Polypropylene resin), polystyrene resin (for example, crystalline polystyrene, amorphous polystyrene), aromatic polyamide resin or polyurethane resin, or glass, carbon, potassium titanate, silicon carbide, silicon nitride Further, fibers composed of inorganic components such as zinc oxide, aluminum borate, and wollastonite can be used.

The thickness of the sheet-like fibrous substance is not particularly limited as long as the effects of the present invention are not impaired.

The electrolyte membrane of the present invention has a dry film thickness of preferably 5 to 200 μm, more preferably 10 to 150 μm. Even when the electrolyte membrane of the present invention is a laminated membrane or a reinforced solid polymer electrolyte membrane, the thickness of the laminated membrane is preferably within this range.

≪Membrane-electrode assembly≫
The membrane-electrode assembly according to the present invention is a membrane-electrode assembly in which a gas diffusion layer, a catalyst layer, an electrolyte membrane of the present invention, a catalyst layer, and a gas diffusion layer are laminated in this order. Specifically, a catalyst layer for the cathode electrode is provided on one surface of the electrolyte membrane of the present invention, a catalyst layer for the anode electrode is provided on the other surface, and each of the catalyst layers for the cathode electrode and the anode electrode is further provided. It is preferable that a gas diffusion layer is provided on each of the cathode electrode side and the anode electrode side in contact with the side opposite to the electrolyte membrane.
Known gas diffusion layers and catalyst layers can be used without particular limitation.

Examples of the gas diffusion layer include a porous substrate or a laminated structure of a porous substrate and a microporous layer. When the gas diffusion layer is composed of a laminated structure of a porous base material and a microporous layer, the microporous layer is preferably in contact with the catalyst layer. The gas diffusion layer preferably contains a fluoropolymer in order to impart water repellency.

The catalyst layer is composed of a catalyst, an ion exchange resin, or the like.
Examples of the catalyst include metal catalysts such as platinum, palladium, gold, ruthenium, iridium, cobalt and iron, and noble metal catalysts such as platinum, palladium, gold, ruthenium and iridium are preferably used. The metal catalyst may contain two or more elements such as an alloy or a mixture. As such a metal catalyst, a catalyst supported on carbon particles having a high specific surface area can be used.

The ion exchange resin serves as a binder component for binding the catalyst, and efficiently supplies ions generated by a reaction on the catalyst to the electrolyte membrane at the anode electrode, and is supplied from the electrolyte membrane at the cathode electrode. A substance that efficiently supplies ions to the catalyst is preferable.

The ion exchange resin is preferably a polymer having a proton exchange group in order to improve proton conductivity in the catalyst layer.
Proton exchange groups contained in such polymers include sulfonic acid groups, carboxylic acid groups, and phosphoric acid groups, but are not particularly limited.

As the ion exchange resin, known ones can be used without particular limitation, and examples thereof include Nafion, the polymer (A) may be used as an ion exchange resin, and further a fluorine having a proton exchange group. It may be a polymer containing atoms, another polymer obtained from ethylene or styrene, a copolymer or a blend thereof.

The catalyst layer may further contain additives such as carbon fiber and a resin not having an ion exchange group, if necessary. This additive is preferably a component having high water repellency, and examples thereof include a fluorine-containing copolymer, a silane coupling agent, a silicone resin, a wax, and polyphosphazene. It is a coalescence.

≪Solid polymer fuel cell≫
The polymer electrolyte fuel cell according to the present invention has the membrane-electrode assembly. Therefore, the polymer electrolyte hydrogen fuel cell according to the present invention is particularly excellent in durability, suppresses a decrease in power generation performance with time, and enables stable power generation over a long period of time.

Specifically, the polymer electrolyte fuel cell according to the present invention includes at least one electricity generating unit including a separator and located on both outer sides of at least one membrane-electrode assembly and its gas diffusion layer; A polymer electrolyte fuel cell comprising: a fuel supply unit for supplying electricity to the electricity generation unit; and an oxidant supply unit for supplying oxidant to the electricity generation unit, wherein the membrane-electrode assembly is as described above preferable.

As the separator, those used in ordinary solid polymer fuel cells can be used. Specifically, a carbon type separator, a metal type separator, or the like can be used.

Further, as a member constituting the polymer electrolyte fuel cell, a known member can be used without any particular limitation. The polymer electrolyte fuel cell of the present invention may be a single cell or a stack cell in which a plurality of single cells are connected in series. A known method can be used as the stacking method. Specifically, it may be planar stacking in which single cells are arranged in a plane, or bipolar in which single cells are stacked via separators each having a fuel or oxidant flow path formed on the back surface of the separator. Stacking may be used.

≪Water electrolysis cell≫
The water electrolysis cell according to the present invention includes a laminate in which the catalyst layer, the electrolyte membrane of the present invention, and the catalyst layer are laminated in this order.
As the catalyst layer, known ones can be used without particular limitation, and specific examples include the same layers as the catalyst layer described in the membrane-electrode assembly.

≪Water electrolysis equipment≫
The water electrolysis apparatus according to the present invention has the water electrolysis cell.

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to these examples.

Hereinafter, the polymer obtained in the synthesis example was evaluated as follows.

[Ion exchange capacity of a polymer having an ion exchange group]
A sample film is prepared from the polymers obtained in Synthesis Examples 1 and 2 below, and the sample film is immersed in deionized water to completely remove the acid remaining in the film. A hydrochloric acid aqueous solution was prepared by immersing in 2 mL of 2N saline per 1 mg to exchange ions. This hydrochloric acid aqueous solution was neutralized with a standard aqueous solution of 0.001N sodium hydroxide using phenolphthalein as an indicator. The membrane after ion exchange was washed with deionized water and vacuum dried at 110 ° C. for 2 hours, and the dry weight of the membrane was measured. As shown in the following formula, an equivalent amount of sulfonic acid groups (hereinafter referred to as “ion exchange capacity”) was determined from the titration amount of sodium hydroxide and the dry weight of the membrane.
Ion exchange capacity (meq / g) = titration amount of sodium hydroxide (mmol) / dry weight of membrane (g)

(Measurement of molecular weight)
The molecular weight was measured using the following two methods depending on the polymer to be measured.
The polymer to be measured is dissolved in an N-methyl-2-pyrrolidone buffer solution (hereinafter referred to as “NMP buffer solution”), the NMP buffer solution is used as an eluent, and TOSOH HLC-8220 (manufactured by Tosoh Corporation) is used as an apparatus. The number average molecular weight (Mn) and the weight average molecular weight (Mw) in terms of polystyrene were determined by gel permeation chromatography (GPC) using TSKgel α-M (manufactured by Tosoh Corporation) as a column.
The NMP buffer solution was prepared at a ratio of NMP (3 L) / phosphoric acid (3.3 mL) / lithium bromide (7.83 g).

The polymer to be measured was dissolved in tetrahydrofuran (THF), THF was used as an eluent, TOSOH HLC-8220 (manufactured by Tosoh Corporation) was used as an apparatus, and TSKgel α-M (manufactured by Tosoh Corporation) was used as a column. The number average molecular weight (Mn) and weight average molecular weight (Mw) in terms of polystyrene were determined by gel permeation chromatography (GPC).

[DSC measurement of polymer (B)]
Using Thermo plus DSC8230 (manufactured by Rigaku Corporation), an aluminum pan encapsulating 1 mg of the polymer (B) obtained in the following synthesis example from 20 ° C. to 300 ° C. in a nitrogen atmosphere at a rate of 5 ° C./min. The temperature was raised and the presence or absence of an endothermic peak in the DSC curve was confirmed.

[Synthesis of a polymer having an ion exchange group]
[Synthesis Example 1]
(1-1) Synthesis of hydrophilic unit To a 1 L flask equipped with a stirrer was added a solution of neopentyl alcohol (45.30 g, 514 mmol) in pyridine (300 mL), followed by 3,5-dichlorobenzenesulfonyl chloride (114 .65 g, 467 mmol) was added in small portions over 15 minutes with stirring. During this time, the reaction temperature was kept at 18-20 ° C. The reaction mixture was stirred for an additional 30 minutes while cooling in an ice bath and then added to ice-cold 10% aqueous HCl (1600 mL). Insoluble components in water were extracted with 700 mL of ethyl acetate, washed twice with 1N aqueous HCl (700 mL each), then twice with 5% aqueous NaHCO ₃ (700 mL each) and then dried over magnesium sulfate. It was. The solvent was removed using a rotary dryer and the residue was recrystallized with 500 mL of methanol. As a result, shiny colorless crystals of neopentyl 3,5-dichlorobenzenesulfonate represented by the following formula (13) were obtained in a yield of 105.98 g and a yield of 76%.

(1-2) Synthesis of polymer having sulfonic acid group Addition system: In a mixture of 29.15 g (98.09 mmol) of the compound represented by the formula (13) and 1.65 g (6.28 mmol) of triphenylphosphine In addition, 71 mL of dehydrated dimethylacetamide (DMAc) was added under nitrogen to prepare an addition system solution.

Reaction system: 2,5-dichlorobenzophenone 23.03 g (91.71 mmol), 2,6-dichlorobenzonitrile 1.75 g (10.19 mmol), triphenylphosphine 1.92 g (7.34 mmol) and zinc 15.99 g In a mixture of (244.57 mmol), 66 mL of dehydrated DMAc was added under nitrogen. This system was heated to 60 ° C. with stirring, and then 1.60 g (2.45 mmol) of bis (triphenylphosphine) nickel dichloride was added to initiate polymerization, followed by stirring at 80 ° C. for 20 minutes. An exotherm and an increase in viscosity were observed with the reaction.

The addition system solution was added to the obtained reaction system under nitrogen. After heating the system to 60 ° C. with stirring, 15.39 g (235.43 mmol) of zinc and 2.05 g (3.14 mmol) of bis (triphenylphosphine) nickel dichloride were added to further promote the polymerization, and 80 ° C. For 3 hours. An exotherm and an increase in viscosity were observed with the reaction.

The obtained solution was diluted with 273 mL of DMAc, and filtered using Celite as a filter aid. To the filtrate, 29.82 g (343.33 mmol) of lithium bromide was added and reacted at 100 ° C. for 7 hours. After the reaction, the reaction solution was cooled to room temperature and poured into 3.2 L of water to be solidified. The solidified product was washed and filtered four times while stirring with acetone. The washed product was washed and filtered seven times while stirring with 1N sulfuric acid. Further, the washed product was washed and filtered with deionized water until the pH of the washing solution became 5 or more. The obtained washed product was dried at 75 ° C. for 24 hours to obtain 25.18 g of a polymer having a target ion exchange group.

The number average molecular weight (Mn) of the molecular weight in terms of polystyrene measured by GPC (solvent: NMP buffer solution) of the polymer having an ion exchange group was 53,000, and the weight average molecular weight (Mw) was 120,000. The ion exchange capacity of this polymer was 2.30 meq / g. When confirmed by NMR, the obtained polymer having an ion exchange group was a polymer having the following structural unit (q: r = 90: 10) (hereinafter also referred to as “polymer (A1)”). .

[Synthesis Example 2]
(2-1) Synthesis of hydrophilic unit 44.9 g (510.2 mmol) of 2,2-dimethylpropanol was dissolved in 147 ml of pyridine. To this solution, 100 g (405.6 mmol) of 2,5-dichlorobenzenesulfonic acid chloride was added at 0 ° C., and the mixture was stirred at room temperature for 1 hour to be reacted. To the reaction mixture, 740 mL of ethyl acetate and 740 mL of 2 mol% aqueous hydrochloric acid were added, stirred for 30 minutes, and allowed to stand to separate the organic layer. The separated organic layer was washed successively with 740 mL of water, 740 mL of a 10 wt% aqueous potassium carbonate solution and 740 mL of saturated brine, and then the solvent was distilled off under reduced pressure. The residue was purified by silica gel column chromatography (chloroform solvent). Subsequently, the solvent was distilled off from the obtained eluate under reduced pressure. Thereafter, the residue was dissolved in 970 mL of hexane at 65 ° C. and then cooled to room temperature. The precipitated solid was separated by filtration. The separated solid was dried to obtain 99.4 g of a white solid of 2,5-dichlorobenzenesulfonic acid (2,2-dimethylpropyl) represented by the following formula in a yield of 82.1%.

(2-2) Synthesis of polymer having sulfonic acid group 1.62 g (12.5 mmol) of anhydrous nickel chloride and 15 mL of dimethyl sulfoxide (DMSO) were mixed in a flask to adjust the internal temperature to 70 ° C. To this, 2.15 g (13.8 mol) of 2,2′-bipyridine was added and stirred at the same temperature for 10 minutes to prepare a nickel-containing solution.

1.49 g (5.0 mmol) of 2,5-dichlorobenzenesulfonic acid (2,2-dimethylpropyl) synthesized in (2-1) and Sumika Excel PES5200P represented by the following formula (S) (Sumitomo Chemical Co., Ltd.) ), Mn = 40000, Mw = 94000) 0.50 g (0.013 mmol) and 5 ml of dimethyl sulfoxide (DMSO) were dissolved in 1.23 g (18.8 mmol) of zinc. Adjusted to 70 ° C.

The nickel-containing solution was poured into the obtained liquid, and a polymerization reaction was performed at 70 ° C. for 4 hours. The reaction mixture was added to 60 mL of methanol, and then 60 mL of a 6 mol / L hydrochloric acid aqueous solution was added to the resulting mixture and stirred for 1 hour. The precipitated solid was separated by filtration and dried to obtain 1.62 g of a grayish white polymerization intermediate. 1.62 g of the obtained polymerization intermediate was added to a mixed solution of 1.13 g (13.0 mmol) of lithium bromide and 56 mL of NMP, and reacted at 120 ° C. for 24 hours. The reaction mixture was poured into 560 mL of 6 mol / L hydrochloric acid aqueous solution and stirred for 1 hour. The precipitated solid was separated by filtration. The separated solid was dried to obtain 0.42 g of an off-white polymer having a target sulfonic acid group.

The number average molecular weight (Mn) of the molecular weight in terms of polystyrene measured by GPC (solvent: NMP buffer solution) of the polymer having a sulfonic acid group was 75000, and the weight average molecular weight (Mw) was 173,000. The ion exchange capacity of this polymer was 1.95 meq / g. The obtained polymer having an ion exchange group was a polymer having the following structural unit (hereinafter also referred to as “polymer (A2)”).

(In the formula, m and n are each independently a value calculated from the charged amount of the raw material forming each structural unit.)

[Synthesis of polymer (B)]
[Synthesis Example 3]
To a 100 mL three-necked flask equipped with a stirrer, thermometer, condenser, Dean-Stark tube and nitrogen-introduced three-way cock, 3.27 g (0.015 mol) of 4,4′-thiodiphenol, 2, 2-bis (4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane 3.36 g (0.010 mol), 2,7-difluorothianthrene (J. Polym. Sci .: Part A: synthesized according to Polym.Chem., 42, 6353-6363 (2004)) 6.31 g (0.025 mol) and 4.49 g (0.033 mol) potassium carbonate were weighed out. After replacing the flask with nitrogen, 37 ml of N, N-dimethylacetamide and 17 ml of toluene were added and stirred. The flask was placed in an oil bath at 140 ° C., and the liquid after stirring was heated to reflux. When water produced by the reaction was azeotroped with toluene and reacted while being removed out of the system with a Dean-Stark tube, almost no water was observed in about 3 hours. After removing most of the toluene while gradually raising the reaction temperature, the reaction was continued at 160 ° C. for 20 hours.

The resulting reaction solution was allowed to cool and then poured into 110 mL of a methanol / 4 wt% sulfuric acid solution (5/1 (volume ratio)). The precipitated product was filtered, and the filtrate was placed in 110 mL of water and stirred at 55 ° C. for 1 hour. The liquid after stirring was filtered, and the residue was again stirred in 110 mL of water at 55 ° C. for 1 hour. Subsequently, the liquid after stirring was filtered, and the filtrate was put into 110 mL of methanol and stirred at 55 ° C. for 1 hour, and then filtered. The filtrate was again put into 110 mL of methanol and stirred and filtered at 55 ° C. for 1 hour. . The filtrate was air-dried and then vacuum-dried at 80 ° C. to obtain 9.91 g of the desired polymer.

The number average molecular weight (Mn) in terms of polystyrene determined by GPC (solvent: tetrahydrofuran) of the obtained target polymer was 2,200, and the weight average molecular weight (Mw) was 6000. Moreover, a melting peak was not confirmed in DSC measurement, and it did not have crystallinity. 20 g or more of the obtained polymer was dissolved in 1 L of a mixed solvent of NMP / methyl ethyl ketone / methanol = 60/20/20 (mass ratio). The obtained polymer was a polymer having the following structural unit (hereinafter also referred to as “polymer (B1)”).

[Synthesis Example 4]
In Synthesis Example 3, 3.27 g (0.015 mol) of 4,4′-thiodiphenol, 2,2-bis (4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane Instead of 36 g (0.010 mol) and 6.31 g (0.025 mol) of 2,7-difluorothianthrene, 5.46 g (0.025 mol) of 4,4′-thiodiphenol, 2,6-dichlorobenzonitrile 7.82 g of the target polymer was obtained in the same manner as in Synthesis Example 3, except that 1.72 g (0.010 mol) and 3.78 g (0.015 mol) of 2,7-difluorothianthrene were used.

The number average molecular weight (Mn) in terms of polystyrene determined by GPC (solvent: tetrahydrofuran) of the obtained target polymer was 2,500, and the polymerization average molecular weight (Mw) was 6000. Moreover, a melting peak was not confirmed in DSC measurement, and it did not have crystallinity. 20 g or more of the obtained polymer was dissolved in 1 L of a mixed solvent of NMP / methyl ethyl ketone / methanol = 60/20/20 (mass ratio). The obtained polymer was a polymer having the following structural unit (hereinafter also referred to as “polymer (B2)”).

[Synthesis Example 5]
Compound (IV) was synthesized according to the following synthetic route.

21.65 g (0.39 mol) of potassium hydroxide was dissolved in 320 g of cooled methanol. To this solution, 59.47 g (0.17 mol) of 9,9-bis (4-hydroxyphenyl) fluorene (compound (I)) was added at a temperature of 10 ° C. or lower, followed by 48 g of N, N-dimethylthiocarbamoyl chloride ( 0.39 mol) was added, the temperature was raised to 60 ° C., and the reaction was carried out for 3 hours. After cooling the reaction solution, the precipitated solid was collected by filtration and washed with 400 mL of a methanol / water mixed solution (50/50 volume ratio). The obtained solid was dissolved in 400 mL of chloroform, and washed with 400 mL of water three times. The chloroform layer was dried over anhydrous magnesium sulfate and concentrated, and then poured into 400 mL of methanol. The precipitate was separated by filtration, and the obtained solid was dried to obtain 77 g (yield 86%) of compound (II).

30 g of diphenyl ether was added to 52 g of compound (II), and reacted at 250 ° C. for 5 hours in a nitrogen atmosphere. The reaction mixture was cooled and then added to 500 mL of methanol, and the precipitate was collected by filtration and dried to obtain compound (III) (yield 91%).

After dissolving 50 g (0.9 mol) of potassium hydroxide in 160 g of cooled methanol, 47 g of compound (III) and 160 g of tetrahydrofuran were added and reacted under reflux conditions for 10 hours. After cooling the reaction mixture, it was poured into 2 L of water and concentrated hydrochloric acid was added until pH = 5. The aqueous layer was separated by decantation to obtain a viscous precipitate. This was dissolved in 600 mL of chloroform and washed 3 times with 600 mL of water. The chloroform layer was dried over anhydrous magnesium sulfate and concentrated. This was put into 1.5 L of methanol, and the precipitate was collected by filtration and dried to obtain 30 g (yield 88%) of 9,9-bis (4-mercaptophenyl) fluorene (compound (IV)).

In Synthesis Example 3, 3.27 g (0.015 mol) of 4,4′-thiodiphenol, 2,2-bis (4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane Instead of 36 g (0.010 mol) and 6.31 g (0.025 mol) of 2,7-difluorothianthrene, 9.56 g (0.35 g) of 9,9-bis (4-mercaptophenyl) fluorene (compound (IV)). 025 mol) and 2,7-difluorothianthrene 6.31 g (0.025 mol) were used in the same manner as in Synthesis Example 3 to obtain 12.42 g of the target polymer.

The number average molecular weight (Mn) in terms of polystyrene determined by GPC (solvent: tetrahydrofuran) of the obtained target polymer was 2,100, and the weight average molecular weight (Mw) was 8,000. Moreover, a melting peak was not confirmed in DSC measurement, and it did not have crystallinity. 20 g or more of the obtained polymer was dissolved in 1 L of a mixed solvent of NMP / methyl ethyl ketone / methanol = 60/20/20 (mass ratio). The obtained polymer was a polymer having the following structural unit (hereinafter also referred to as “polymer (B3)”).

[Synthesis Example 6]
To a 100 mL three-necked flask equipped with a stirrer, thermometer, condenser, Dean-Stark tube and nitrogen-introduced three-way cock, 3.42 g (0.03 mol) of 1,4-difluorobenzene, 2,6- 4.17 g (0.03 mol) of dichlorobenzonitrile and 4.68 g (0.06 mol) of sodium sulfide were weighed out. After the flask was purged with nitrogen, 25 ml of NMP and 13 ml of toluene were added and stirred. The flask was placed in an oil bath at 140 ° C., and the liquid after stirring was heated to reflux. When water produced by the reaction was azeotroped with toluene and reacted while being removed out of the system with a Dean-Stark tube, almost no water was observed in about 3 hours. After removing most of the toluene while gradually raising the reaction temperature, the reaction was continued at 190 ° C. for 20 hours.

The resulting reaction solution was allowed to cool and then poured into 90 mL of a methanol / 4 wt% sulfuric acid solution (5/1 (volume ratio)). The precipitated product was filtered, and the filtrate was placed in 90 mL of water and stirred at 55 ° C. for 1 hour. The liquid after stirring was filtered, and the residue was again stirred in 90 mL of water at 55 ° C. for 1 hour. Subsequently, the liquid after stirring was filtered, and the filtrate was put into 90 mL of methanol and stirred at 55 ° C. for 1 hour, and then filtered. The filtrate was again put into 90 mL of methanol and stirred at 55 ° C. for 1 hour and filtered. . The filtrate was air-dried and then vacuum-dried at 80 ° C. to obtain 9.91 g of the desired polymer.

The number average molecular weight (Mn) in terms of polystyrene determined by GPC (solvent: NMP buffer solution) of the obtained target polymer was 2,500, and the weight average molecular weight (Mw) was 6000. Moreover, a melting peak was not confirmed in DSC measurement, and it did not have crystallinity. 20 g or more of the obtained polymer was dissolved in 1 L of a mixed solvent of NMP / methyl ethyl ketone / methanol = 60/20/20 (mass ratio). The obtained polymer was a polymer having the following structural unit (hereinafter also referred to as “polymer (B4)”).

[Synthesis Example 7]
In Synthesis Example 3, instead of 3.27 g (0.015 mol) of 4,4′-thiodiphenol, 5.38 g (0.015 mol) of 4,4′-thio-bis (6-tert-butyl-m-cresol) was used. ) Was used in the same manner as in Synthesis Example 3 except that 8.85 g of the target polymer was obtained.

The number average molecular weight (Mn) in terms of polystyrene determined by GPC (solvent: tetrahydrofuran) of the obtained target polymer was 1,400, and the weight average molecular weight (Mw) was 2,200. Moreover, a melting peak was not confirmed in DSC measurement, and it did not have crystallinity. 20 g or more of the obtained polymer was dissolved in 1 L of a mixed solvent of NMP / methyl ethyl ketone / methanol = 60/20/20 (mass ratio). The obtained polymer was a polymer having the following structural unit (hereinafter also referred to as “polymer (B5)”).

[Example 1]
15 g of the polymer (A1) obtained in Synthesis Example 1 and 0.47 g of the polymer (B1) obtained in Synthesis Example 3 are mixed solvents of NMP / methyl ethyl ketone / methanol = 60/20/20 (mass ratio). The solution dissolved in 85 ml was cast coated on a PET film with a die coater, pre-dried at 80 ° C. for 40 minutes, and then dried at 120 ° C. for 40 minutes. The dried PET film with a coating film is immersed in a large amount of distilled water overnight to remove residual NMP in the coating film, and then air-dried. The polymer (A1) and the polymer (B1) have a mass ratio (heavy weight) The electrolyte membrane 1 was obtained that was contained in a combination (A1) / polymer (B1)) 97/3 and had a thickness of 40 μm.

[Performance evaluation]
(1) Platinum poisoning test A platinum disk electrode with a surface area of 0.785 mm ² is immersed in a 1N sulfuric acid aqueous solution degassed with N ₂ gas, a sweep rate of 0.01 V / s, and a sweep potential range of 0.05 to 1.5 V. The platinum voltammetry was performed by repeating the sweep until the cyclic voltammogram became constant, and a platinum disk electrode having a clean surface was obtained. In addition, the amount of electricity of the hydrogen desorption wave of the last measured cyclic voltammogram was the amount of electricity measured when the electrode surface was clean.

Next, the electrolyte membrane 1 (thickness 40 μm, area 9 cm ² , that is, volume 0.036 cm ³ ) peeled from the PET film is placed in a container containing 50 mL of 1N sulfuric acid aqueous solution, and the container is sealed and sealed at 80 ° C. for 100 hours. The heated aqueous solution was collected as a test solution. A platinum disk electrode surface having a clean surface was immersed in a test solution deaerated with N ₂ gas, and cyclic voltammetry was measured for 20 cycles at a sweep rate of 0.01 V / s and a sweep potential range of 0.05 to 0.4 V. . The amount of electricity of the hydrogen desorption wave at the 20th cycle was obtained, and this was used as the amount of electricity measured when the electrode surface was poisoned, and the poisoning rate of platinum was obtained from the following formula.
Platinum poisoning rate (%) = [(quantity of electricity measured when electrode surface is clean) − (quantity of electricity measured when electrode surface is poisoned)] × 100 / (clean electrode surface) Measured quantity of electricity)

A platinum wire was used as the counter electrode for cyclic voltammetry, and a reversible hydrogen electrode was used as the reference electrode. Further, during cyclic voltammetry, N ₂ gas was kept flowing to prevent air from entering the portion above the electrolyte in the electrochemical cell. The measurement was performed at room temperature. The results are shown in Table 1.

[Example 2]
In Example 1, a polymer (A1) and a polymer (B2) were obtained in the same manner as in Example 1 except that the polymer (B2) obtained in Synthesis Example 4 was used instead of the polymer (B1). Was obtained at a mass ratio of 97/3, and an electrolyte membrane 2 having a thickness of 40 μm was obtained. Using this electrolyte membrane, the same platinum poisoning test as in Example 1 was performed. The results are shown in Table 1.

[Example 3]
In Example 1, the polymer (B3) obtained in Synthesis Example 5 was used instead of the polymer (B1), and NMP / methanol = 80/20 (mass ratio) was used as the mixed solvent. In the same manner as described above, an electrolyte membrane 3 containing the polymer (A1) and the polymer (B3) at a mass ratio of 97/3 and having a film thickness of 40 μm was obtained. Using this electrolyte membrane, the same platinum poisoning test as in Example 1 was performed. The results are shown in Table 1.

[Example 4]
In Example 3, the polymer (A1) and the polymer (B4) were obtained in the same manner as in Example 3 except that the polymer (B4) obtained in Synthesis Example 6 was used instead of the polymer (B3). Was obtained at a mass ratio of 97/3, and an electrolyte membrane 4 having a thickness of 40 μm was obtained. Using this electrolyte membrane, the same platinum poisoning test as in Example 1 was performed. The results are shown in Table 1.

[Example 5]
Dispersion in which SnO ₂ was dispersed by adding 3.9 g of EPS-12A (12 wt% SnO ₂ aqueous dispersion, manufactured by Yamanaka Sangyo Co., Ltd.) to 85 mL of a mixed solvent of NMP / methyl ethyl ketone / methanol = 60/20/20 (mass ratio). The same procedure as in Example 1 was performed except that 15 g of the polymer (A1) obtained in Synthesis Example 1 and 0.47 g of the polymer (B1) obtained in Synthesis Example 3 were dissolved in the solution. Thus, an electrolyte membrane 5 was obtained. The electrolyte membrane 5 includes a polymer (A1), a polymer (B1), and SnO ₂ (metal component) at a mass ratio (polymer (A1) / polymer (B1) / metal component) 94/3/3. The film thickness was 40 μm. Using this electrolyte membrane 5, the same platinum poisoning test as in Example 1 was conducted. The results are shown in Table 1.

[Example 6]
In Example 3, the polymer (A1) and the polymer (B5) were used in the same manner as in Example 3 except that the polymer (B5) obtained in Synthesis Example 7 was used instead of the polymer (B3). Was obtained at a mass ratio of 97/3, and an electrolyte membrane 6 having a film thickness of 40 μm was obtained. Using this electrolyte membrane, the same platinum poisoning test as in Example 1 was performed. The results are shown in Table 1.

[Example 7]
In Example 1, the polymer (A2) and the polymer (B1) were obtained in the same manner as in Example 1 except that the polymer (A2) obtained in Synthesis Example 2 was used instead of the polymer (A1). Was obtained at a mass ratio of 97/3, and an electrolyte membrane 7 having a thickness of 40 μm was obtained. Using this electrolyte membrane, the same platinum poisoning test as in Example 1 was performed. The results are shown in Table 1.

[Example 8]
In Example 1, 71.4 ml of Nafion D2020 (manufactured by DuPont, polymer concentration 21% dispersion, ion exchange capacity 1.08 meq / g) was used instead of the polymer (A1), NMP was added, and water was added. In addition, Nafion and polymer (B1) were contained at a mass ratio of 97/3 in the same manner as in Example 1 except that the total amount of NMP was changed to 85 ml by distilling off 1-propanol and replacing the solvent. An electrolyte membrane 8 having a thickness of 40 μm was obtained. Using this electrolyte membrane, the same platinum poisoning test as in Example 1 was performed. The results are shown in Table 1.

[Comparative Example 1]
In Example 1, polymer (A1) and thianthrene were in a mass ratio of 97/3 in the same manner as in Example 1 except that thianthrene (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of polymer (B1). An electrolyte membrane having a thickness of 40 μm was obtained. Using this electrolyte membrane, the same platinum poisoning test as in Example 1 was performed. The results are shown in Table 1.

[Comparative Example 2]
In Example 1, an electrolyte membrane having a thickness of 40 μm was obtained in the same manner as in Example 1 except that the polymer (B1) was not used. Using this electrolyte membrane, the same platinum poisoning test as in Example 1 was performed. The results are shown in Table 1.

[Comparative Example 3]
15 g of the polymer (A1) obtained in Synthesis Example 1 and 0.47 g of polyphenylene sulfide (PPS, Sigma-Aldrich Japan, melting point 285 to 300 ° C.) NMP / methyl ethyl ketone / methanol = 60/20/20 (mass) The PPS was not dissolved when trying to dissolve in 85 ml of the mixed solvent of the ratio), and thus the electrolyte membrane could not be produced by cast coating.

〔Evaluation results〕
From Table 1, the electrolyte membranes obtained in Examples 1 to 8 and Comparative Example 2 have a low platinum poisoning rate even at high temperatures, and there is little concern about performance degradation due to a decrease in catalytic activity during battery power generation or water decomposition. It was a membrane. On the other hand, the electrolyte membrane obtained in Comparative Example 1 has a high platinum poisoning rate, and is a membrane in which the power generation performance and the water resolution are liable to be lowered due to a decrease in catalytic activity.

[Preparation of anode electrode paste]
In a 200 mL plastic bottle, 80 g of zirconia balls having a diameter of 5 mm (“YTZ balls” manufactured by Nikkato Co., Ltd.) are placed, platinum ruthenium-supporting carbon particles (“TEC61E54” manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.), Pt: 29.8% by mass, Ru: 23.2% by mass supported) 1.28 g, distilled water 3.60 g, n-propyl alcohol 12.02 g and Nafion D2020 (manufactured by DuPont, polymer concentration 21% dispersion, ion exchange capacity 1.08 meq / g) After adding 3.90 g and stirring with a paint shaker for 60 minutes, an anodic electrode paste was obtained by removing zirconia balls.

[Preparation of cathode electrode paste]
Next, 80 g of zirconia balls (YTZ balls) having a diameter of 5 mm are placed in a 200 ml plastic bottle, and platinum-supported carbon particles (“TEC10E50E” manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., Pt: 45.6% by mass) 1.25 g, distilled 3.64 g of water, 11.91 g of n-propyl alcohol and Nafion D2020 (4.40 g) were added, and the mixture was stirred for 60 minutes with a paint shaker, and then the zirconia balls were removed to obtain a cathode electrode paste.

[Example 9]
[Production of electrodes]
Using the mask having an opening of 5 cm × 5 cm on one side (the side opposite to the PET film) of the electrolyte membrane 1 with the PET film obtained in Example 1, the anode electrode paste was applied with a doctor blade, and the PET film Then, the cathode electrode paste was applied with a doctor blade using a mask having an opening of 5 cm × 5 cm on the peeled surface. This was dried at 120 ° C. for 60 minutes to obtain a laminate in which catalyst layers were formed on both surfaces of the electrolyte membrane. The catalyst coating amount of each catalyst layer was 0.50 mg / cm ² .

[Gas diffusion layer]
GDL24BC manufactured by SGL CARBON was used as the gas diffusion layer.

[Production of polymer electrolyte fuel cells]
The electrolyte membrane having the catalyst layer formed on both sides was sandwiched between two gas diffusion layers and hot-pressed at 160 ° C. for 20 minutes under a pressure of 60 kg / cm ² to prepare a membrane-electrode assembly. A separator also serving as a gas flow path is laminated on the gas diffusion layer of the obtained membrane-electrode assembly, and is sandwiched between two titanium current collectors. ^Two evaluation fuel cells were prepared.

[Performance evaluation]
(2) OCV (open circuit voltage) durability test Supply air at a normal pressure and a flow rate of 0.2 L / min to the cathode electrode side (the side where the electrolyte electrode cathode electrode paste was applied) of the fuel cell for evaluation obtained Then, pure hydrogen was supplied to the anode electrode side (side where the anode electrode paste of the electrolyte membrane was applied) at a flow rate of 0.2 L / min at normal pressure, the cell temperature was 90 ° C., the cathode electrode side relative humidity was 20%, When the anode electrode side relative humidity is set to 20%, voltage is measured when the circuit is operated for 300 hours in the open circuit state without power generation (initial stage) and when the circuit is operated for 300 hours without power generation. The rate of decline was measured. The results are shown in Table 2.

(3) Output voltage measurement before and after the OCV durability test Air was supplied to the cathode electrode side of the obtained fuel cell for evaluation at a back pressure of 120 kPa and a utilization factor of 40%, and a back pressure of 120 kPa and a utilization factor of 70% to the anode electrode side. The cell voltage at a current density of 1 A / cm ² was measured by supplying pure hydrogen, setting the cell temperature to 80 ° C., the cathode electrode side relative humidity to 50%, and the anode electrode side relative humidity to 50% (initial). In addition, the cell voltage at a current density of 1 A / cm ² after 300 hours of operation in an open circuit state was measured. From these results, the degree of decrease in cell voltage before and after the OCV durability test was determined. The results are shown in Table 2.

[Example 10]
In Example 9, evaluation was performed in the same manner as in Example 9 except that instead of the electrolyte membrane 1 with PET film obtained in Example 1, the electrolyte membrane 2 with PET film obtained in Example 2 was used. A fuel cell was prepared, and an OCV durability test and an output voltage measurement before and after the OCV durability test were performed using the fuel cell. The results are shown in Table 2.

[Example 11]
In Example 9, evaluation was performed in the same manner as in Example 9 except that instead of the electrolyte membrane 1 with PET film obtained in Example 1, the electrolyte membrane 3 with PET film obtained in Example 3 was used. A fuel cell was prepared, and an OCV durability test and an output voltage measurement before and after the OCV durability test were performed using the fuel cell. The results are shown in Table 2.

[Example 12]
In Example 9, evaluation was performed in the same manner as in Example 9 except that instead of the electrolyte membrane 1 with PET film obtained in Example 1, the electrolyte membrane 4 with PET film obtained in Example 4 was used. A fuel cell was prepared, and an OCV durability test and an output voltage measurement before and after the OCV durability test were performed using the fuel cell. The results are shown in Table 2.

[Example 13]
In Example 9, evaluation was performed in the same manner as in Example 9 except that instead of the electrolyte membrane 1 with PET film obtained in Example 1, the electrolyte membrane 5 with PET film obtained in Example 5 was used. A fuel cell was prepared, and an OCV durability test and an output voltage measurement before and after the OCV durability test were performed using the fuel cell. The results are shown in Table 2.

[Example 14]
In Example 9, instead of the electrolyte membrane 1 with PET film obtained in Example 1, the evaluation was performed in the same manner as in Example 9 except that the electrolyte membrane 6 with PET film obtained in Example 6 was used. A fuel cell was prepared, and an OCV durability test and an output voltage measurement before and after the OCV durability test were performed using the fuel cell. The results are shown in Table 2.

[Example 15]
In Example 9, instead of the electrolyte membrane 1 with PET film obtained in Example 1, the evaluation was performed in the same manner as in Example 9 except that the electrolyte membrane 7 with PET film obtained in Example 7 was used. A fuel cell was prepared, and an OCV durability test and an output voltage measurement before and after the OCV durability test were performed using the fuel cell. The results are shown in Table 2.

[Example 16]
In Example 9, instead of the electrolyte membrane 1 with PET film obtained in Example 1, the evaluation was performed in the same manner as in Example 9 except that the electrolyte membrane 8 with PET film obtained in Example 8 was used. A fuel cell was prepared, and an OCV durability test and an output voltage measurement before and after the OCV durability test were performed using the fuel cell. The results are shown in Table 2.

[Example 17]
5 g of the polymer (A1) obtained in Synthesis Example 1 and 0.55 g of the polymer (B1) obtained in Synthesis Example 3 are mixed solvents of NMP / methyl ethyl ketone / methanol = 60/20/20 (mass ratio). The solution dissolved in 95 mL was cast-coated on a PET film with a die coater so that the thickness after drying was 1 μm, and pre-dried at 80 ° C. for 40 minutes. From that, a solution obtained by dissolving 15 g of the polymer (A1) obtained in Synthesis Example 1 in 85 mL of a mixed solvent of NMP / methyl ethyl ketone / methanol = 60/20/20 (mass ratio) was cast coated with a die coater. The sample was pre-dried at 80 ° C. for 40 minutes and then dried at 120 ° C. for 40 minutes. The dried PET film with a coating film was immersed in a large amount of distilled water overnight to remove the remaining NMP in the coating film. After that, by air drying, the polymer (A1) and the polymer (B1) are contained in a mass ratio (polymer (A1) / polymer (B1)) 90/10 on the PET film. A layered product (electrolyte membrane 9, 40 μm) in which the layer (F1) and the layer (F2) having a thickness of 39 μm and consisting only of the polymer (A1) were laminated in this order was obtained. The mass ratio (polymer (A1) / polymer (B1)) of the polymer (A1) and the polymer (B1) in the entire electrolyte membrane 9 was 99.72 / 0.28.

In Example 9, instead of the electrolyte membrane 1 with PET film obtained in Example 1, the electrolyte membrane 9 with PET film was used, and the cathode electrode paste was layered on the surface (F1) and the anode electrode paste was layered. (F2) A fuel cell for evaluation was prepared in the same manner as in Example 9 except that it was applied to the surface, and an OCV durability test and an output voltage measurement before and after the OCV durability test were performed using the fuel cell. The results are shown in Table 2.

[Example 18]
5 g of the polymer (A1) obtained in Synthesis Example 1 and 0.55 g of the polymer (B1) obtained in Synthesis Example 3 are mixed solvents of NMP / methyl ethyl ketone / methanol = 60/20/20 (mass ratio). The solution dissolved in 95 ml was cast-coated on a PET film with a die coater so that the thickness after drying was 1 μm, and pre-dried at 80 ° C. for 40 minutes. From that, a solution obtained by dissolving 15 g of the polymer (A1) obtained in Synthesis Example 1 in 85 ml of a mixed solvent of NMP / methyl ethyl ketone / methanol = 60/20/20 (mass ratio) was cast coated with a die coater, Pre-dried at 80 ° C. for 40 minutes. Subsequently, 5 g of the polymer (A1) obtained in Synthesis Example 1 and 0.55 g of the polymer (B1) obtained in Synthesis Example 3 were added onto the pre-dried coating film with NMP / methyl ethyl ketone / methanol. = 60/20/20 (mass ratio) solution dissolved in 95 ml of mixed solvent was cast coated with a thickness of 1 μm after drying with a die coater, and preliminarily prepared at 80 ° C. for 40 minutes. After drying, it was dried at 120 ° C. for 40 minutes. The dried PET film with a coating film was immersed in a large amount of distilled water overnight to remove the remaining NMP in the coating film. Thereafter, the film is air-dried, and the polymer (A1) and the polymer (B1) are contained in a mass ratio (polymer (A1) / polymer (B1)) 90/10 on the PET film. A laminate (electrolyte film 10, thickness 40 μm) in which a layer (F4) having a thickness of 38 μm and a layer (F3) made of only (F3), the polymer (A1), and the layer (F3) was obtained in this order was obtained. The mass ratio (polymer (A1) / polymer (B1)) of the polymer (A1) and the polymer (B1) in the entire electrolyte membrane 8 was 99.5 / 0.5.

In Example 9, instead of the electrolyte membrane 1 with PET film obtained in Example 1, an evaluation fuel cell was prepared in the same manner as in Example 9 except that the electrolyte membrane 10 with PET film was used. Using the fuel cell, an OCV durability test and an output voltage measurement before and after the OCV durability test were performed. The results are shown in Table 2.

[Example 19]
15 g of the polymer (A1) obtained in Synthesis Example 1 and 0.47 g of the polymer (B1) obtained in Synthesis Example 3 are mixed solvents of NMP / methyl ethyl ketone / methanol = 60/20/20 (mass ratio). The solution dissolved in 85 ml was cast coated on a PET film with a die coater. On this coating liquid, a high molecular weight polyethylene porous substrate (manufactured by Lydall, SOLUPOR (registered trademark), 3P07A; specific gravity 3.0 g / m ² , air permeability 1.4 s / 50 ml, porosity 83 %, Thickness 20 μm). Further, the solution was cast again from the side of the porous substrate not in contact with the coating solution, and both surfaces of the porous substrate were impregnated with the solution. Next, after preliminary drying at 80 ° C. for 40 minutes, drying was performed at 120 ° C. for 40 minutes to obtain a laminate in which a coating film was formed on both surfaces of the substrate. The laminated body after drying is immersed in a large amount of distilled water overnight, the remaining NMP in the coating film is removed, and then air-dried to be reinforced with a porous substrate made of high molecular weight polyethylene, and the polymer (A1) and An electrolyte membrane 11 having a thickness of 20 μm was obtained, in which the mass ratio of polymer (B1) to polymer (A1) / polymer (B1) was 97/3.

In Example 9, an evaluation fuel cell was prepared in the same manner as in Example 9 except that the electrolyte membrane 11 was used instead of the electrolyte membrane 1 with the PET film obtained in Example 1. The OCV durability test and the output voltage measurement before and after the OCV durability test were performed. The results are shown in Table 2.

[Comparative Example 4]
Fuel for evaluation in the same manner as in Example 9, except that the electrolyte membrane with PET film obtained in Comparative Example 2 was used instead of the electrolyte membrane with PET film obtained in Example 1 in Example 9. A battery was prepared, and an OCV durability test and an output voltage measurement before and after the OCV durability test were performed using the fuel cell. The results are shown in Table 2.

[Comparative Example 5]
Fuel for evaluation in the same manner as in Example 9 except that the electrolyte membrane with PET film obtained in Comparative Example 1 was used instead of the electrolyte membrane with PET film obtained in Example 1 in Example 9. A battery was created. The fuel cell was used to measure the OCV durability test and the output voltage before and after the OCV durability test. The initial voltage could not be measured due to platinum catalyst poisoning. could not.

〔Evaluation results〕
It was found that the fuel cells obtained in Examples 9 to 19 had a lower open circuit voltage decrease rate than the fuel cell obtained in Comparative Example 4. Further, it was found that the fuel cells obtained in Examples 9 to 19 had a cell voltage decrease degree before and after the OCV endurance test smaller than the fuel cell obtained in Comparative Example 4. From the above, it can be seen that the electrolyte membrane of the present invention has excellent power generation performance and excellent durability.

Claims

An electrolyte membrane composition comprising a polymer (A) having an ion exchange group and a polymer (B) having an arylene sulfide skeleton and soluble in an organic solvent.
The composition for an electrolyte membrane according to claim 1, wherein the polymer (B) does not have crystallinity.
The composition for electrolyte membrane of Claim 1 or 2 in which the said polymer (B) contains at least either of the structural unit represented by following formula (1) or (2).

[In Formula (1), R 1 and R 2 are each independently an alkyl group having 1 to 5 carbon atoms, an alkylsulfanyl group having 1 to 5 carbon atoms, a cyano group or a halogen atom, and a and b are each Independently, it is an integer of 0 to 3. X 1 and X 2 are each independently a direct bond, —S—, —NH—, —SO— or —SO 2 —, but at least one of X 1 and X 2 is —S—. ]

[In the formula (2), R 3 represents an alkyl group having 1 to 5 carbon atoms, an alkylsulfanyl group having 1 to 5 carbon atoms, a cyano group, or a halogen atom, and c represents an integer of 0 to 4. ]
The composition for an electrolyte membrane according to any one of claims 1 to 3, wherein the polymer (B) contains at least one of structural units represented by the following formulas (3) to (5).

Wherein (3), R 1, R 2, X 1, X 2, a and b are each independently, R 1 in the formula (1), R 2, X 1, X 2, a and b Is synonymous with ]

[In the formulas (4) and (5), R 3 and c are each independently synonymous with R 3 and c in the formula (2). ]
The composition for an electrolyte membrane according to any one of claims 1 to 4, wherein the polymer (B) has at least one group selected from the group consisting of a polar group, a group containing a fluorine atom, and a fluorenylidene group. object.
The composition for an electrolyte membrane according to any one of claims 1 to 5, wherein the polymer (B) has a structural unit represented by the following formula (7).

[In the formula (7), D is independently a direct bond, —CO—, —SO 2 —, —SO—, —CONH—, —COO—, — (CF 2 ) 1 — (l is 1 to 10 -C (CF 3 ) 2 -,-(CH 2 ) l- (l is an integer of 1 to 10), -C (CR ' 3 ) 2- (R' is independently A cyclohexylidene group, a fluorenylidene group, —O— or —S—, and A and E are each independently a direct bond, —O— or —S—. R 4 to R 11 are each independently a hydrogen atom, a fluorine atom, an alkyl group, an allyl group, an aryl group, a halogenated alkyl group in which some or all of the hydrogen atoms are halogenated, a nitro group, or a cyano group. And r is an integer of 0-4. However, the structural unit represented by Formula (7) is not the structural unit represented by Formula (2). ]
The composition for an electrolyte membrane according to any one of claims 1 to 6, wherein the number average molecular weight of the polymer (B) is in the range of 1,000 to 10,000.
The composition for an electrolyte membrane according to any one of claims 1 to 7, further comprising at least one metal component selected from the group consisting of a metal-containing compound and a metal ion.
A solid polymer electrolyte membrane obtained from the electrolyte membrane composition according to any one of claims 1 to 8.
After the electrolyte membrane (volume 0.036 cm 3 ) was immersed in 50 mL of 1N sulfuric acid aqueous solution at 80 ° C. for 100 hours, the platinum surface with a surface area of 0.785 mm 2 was swept into the aqueous solution obtained by removing the electrolyte membrane. 10. The platinum poisoning rate when immersed for 20 cycles of cyclic voltammetry at a speed of 0.01 V / s and a sweep potential range of 0.05 to 0.4 V is 20% or less. The solid polymer electrolyte membrane described.
The solid polymer electrolyte membrane according to claim 9 or 10, wherein the polymer (B) is present at least at a position within 30% from the surface of the electrolyte membrane with respect to the thickness of the electrolyte membrane.
The method for producing a solid polymer electrolyte membrane according to any one of claims 9 to 11, comprising a step of applying the electrolyte membrane composition according to any one of claims 1 to 8.
A membrane-electrode assembly in which a gas diffusion layer, a catalyst layer, the solid polymer electrolyte membrane according to any one of claims 9 to 11, a catalyst layer, and a gas diffusion layer are laminated in this order.
A polymer electrolyte fuel cell comprising the membrane-electrode assembly according to claim 13.
A water electrolysis cell in which a catalyst layer, the solid polymer electrolyte membrane according to any one of claims 9 to 11 and a catalyst layer are laminated in this order.
A water electrolysis apparatus comprising the water electrolysis cell according to claim 15.