JP2015220018A - Hydrocarbon based polymer electrolyte membrane, membrane-electrode assembly, and fuel cell - Google Patents

Abstract

A method for suppressing a decrease in proton conductivity of a polymer electrolyte membrane for a fuel cell is provided. A hydrocarbon polymer electrolyte membrane disposed between an anode and a cathode, wherein the outermost layer of at least one of the anode side layer and the cathode side layer of the hydrocarbon polymer electrolyte membrane is provided. The water absorption rate is larger than the water absorption rate of the adjacent layer, preferably the difference between the water absorption rate of the outermost layer on the anode side and the water absorption rate of the adjacent layer is 5% or more, and the hydrocarbon-based polymer electrolyte membrane Is a laminate having two or more layers containing an ion-exchange group-containing hydrocarbon polymer, and at least one outermost layer of the laminate and the layer in contact with the layer have substantially the same molecular structure A method of forming a layer containing an ion-exchange group-containing hydrocarbon polymer having: [Selection figure] None

Description

  The present invention relates to a hydrocarbon-based polymer electrolyte membrane, a membrane-electrode assembly, and a fuel cell.

Conventionally, studies have been made on hydrocarbon polymer electrolyte membranes for use in fuel cells and the like.
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 includes a pair of gas diffusion layers (anode-side gas diffusion layer and cathode-side gas diffusion layer) in which catalyst layers are stacked, and a polymer electrolyte membrane sandwiched between the gas diffusion layers. Including the membrane-electrode assembly, the anode electrode generates hydrogen ions and electrons, and the hydrogen ions pass through the polymer electrolyte membrane and react with oxygen at the cathode electrode to generate water.

  In such a fuel cell, it is important from the viewpoint of proton conductivity that the polymer electrolyte membrane contains water, but as the reaction proceeds, the polymer electrolyte membrane on the anode side progresses. The moisture content in the inside may decrease (dry out), and the proton conductivity of the polymer electrolyte membrane may decrease.

  Various studies have been conducted to suppress this phenomenon. For example, Patent Document 1 discloses that a gas diffusion layer to be used has a specific configuration.

JP 2013-191321 A

  However, conventional proton conducting membranes and membrane-electrode assemblies have room for further improvement in order to suppress a decrease in proton conductivity.

  An object of the present invention is to provide a polymer electrolyte membrane excellent in proton conductivity.

Under such circumstances, the present inventors have intensively studied to solve the above problems, and as a result, the water absorption rate of at least one of the anode side layer and the cathode side layer of the polymer electrolyte membrane is adjacent. According to the hydrocarbon-based polymer electrolyte membrane having a larger water absorption rate than the layer, the inventors have found that the above object can be achieved, and have completed the present invention.
A configuration example of the present invention is as follows.

  [1] A hydrocarbon-based polymer electrolyte membrane disposed between an anode and a cathode, wherein the water absorption rate of at least one of the anode side layer and the cathode side layer of the polymer electrolyte membrane is adjacent to each other. A hydrocarbon-based polymer electrolyte membrane, wherein the water absorption rate of the layer is larger.

[2] The hydrocarbon-based polymer electrolyte membrane according to [1], wherein the water absorption rate of the anode-side outermost layer of the polymer electrolyte membrane is larger than the water absorption rate of a layer adjacent thereto.
[3] The hydrocarbon-based polymer electrolyte according to [1] or [2], wherein the difference between the water absorption rate of the outermost layer on the anode side of the polymer electrolyte membrane and the water absorption rate of the adjacent layer is 5% or more. film.

[4] The hydrocarbon polymer according to any one of [1] to [3], wherein the polymer electrolyte membrane is a laminate having two or more layers containing an ion exchange group-containing hydrocarbon polymer. Electrolyte membrane.
[5] Among the laminates, at least one outermost layer and a layer in contact with the layer are layers containing an ion exchange group-containing hydrocarbon polymer having substantially the same molecular structure. [4] The hydrocarbon-based polymer electrolyte membrane described in 1.

[6] Of the polymer electrolyte membrane, at least the anode-side outermost layer is
A step (C) of forming a coating film from a composition containing an ion exchange group-containing hydrocarbon polymer and a good solvent for the polymer; and
Step (D) in which the coating film obtained in Step (C) is exposed to an atmosphere of water or a poor solvent for the polymer.
The hydrocarbon-based polymer electrolyte membrane according to any one of [1] to [5], which is a layer obtained by a method comprising:

[7] Of the polymer electrolyte membrane, at least the anode-side outermost layer contains an ion-exchange group-containing hydrocarbon polymer, and the outermost layer comprises:
A step of bringing the outermost part or outermost layer of the membrane to be the polymer electrolyte membrane into contact with a solvent containing a good solvent for the ion-exchange group-containing hydrocarbon-based polymer constituting the part or layer (A), and
Exposing the polymer electrolyte membrane obtained in step (A) to an atmosphere of water or a poor solvent for the polymer (B)
The hydrocarbon-based polymer electrolyte membrane according to any one of [1] to [5], which is a layer obtained by a method comprising:

  [8] The hydrocarbon-based polymer electrolyte according to any one of [4] to [7], wherein the anode-side outermost layer has a thickness of 1 to 70% of the total thickness of the laminate. film.

[9] Of the polymer electrolyte membrane, at least the cathode-side outermost layer is
A step (C) of forming a coating film from a composition containing an ion exchange group-containing hydrocarbon polymer and a good solvent for the polymer; and
The hydrocarbon system according to any one of [1] to [8], which is a layer obtained by a method including the step (E) in which the coating film obtained in the step (C) is heated in air or under vacuum. Polymer electrolyte membrane.

  [10] The hydrocarbon-based polymer electrolyte membrane according to [6] or [9], wherein the composition contains a crosslinking agent.

[11] A membrane-electrode assembly in which a gas diffusion layer, a catalyst layer, the hydrocarbon-based polymer electrolyte membrane according to any one of [1] to [10], a catalyst layer, and a gas diffusion layer are laminated in this order.
[12] A fuel cell having the membrane-electrode assembly according to [11].

  According to the present invention, a polymer electrolyte membrane excellent in proton conductivity over a long period can be provided.

≪Hydrocarbon polymer electrolyte membrane≫
A hydrocarbon-based polymer electrolyte membrane according to the present invention (hereinafter, also simply referred to as “electrolyte membrane”) is a hydrocarbon-based electrolyte membrane disposed between an anode and a cathode, and is an anode of the electrolyte membrane. The water absorption rate of at least one of the side layer and the cathode side layer is greater than the water absorption rate of an adjacent layer (however, this layer is a layer constituting an electrolyte membrane; the same shall apply hereinafter), It is preferable that the water absorption rate of the outermost layer on the anode side of the electrolyte membrane is larger than the water absorption rate of a layer adjacent thereto.
Such an electrolyte membrane is excellent in proton conductivity over a long period of time. Moreover, it is thought that dry-out can be suppressed by using such an electrolyte membrane.

During operation of the fuel cell, water stays around the cathode catalyst layer, and the supply of reaction gas (air) to the cathode catalyst layer may be hindered (this phenomenon is also called “flooding”). .) When this flooding occurs, the reactivity at the cathode decreases, resulting in a decrease in power generation efficiency of the fuel cell.
By using an electrolyte membrane in which the water absorption rate of the outermost layer on the anode side is larger than the water absorption rate of the layer adjacent to it, the water generated on the cathode side easily moves to the anode side. It is also possible to suppress this.

The electrolyte membrane of the present invention is not particularly limited as long as the water absorption rate of the outermost layer of at least one of the anode side layer and the cathode side layer is larger than the water absorption rate of the adjacent layer, but the electrolyte membrane is excellent in proton conductivity over a longer period of time. The water absorption rate of the anode outermost layer is preferably larger than the water absorption rate of the adjacent layer, and the difference between the water absorption rate of the anode outermost layer and the water absorption rate of the adjacent layer is 5 % Or more, preferably 10% or more. The difference in water absorption is preferably 2000% or less, and more preferably 1500% or less. This water absorption can be adjusted by changing the ion exchange capacity of the polymer contained in the electrolyte membrane, but in the present invention, the electrolyte membrane is formed by a specific production method, for example, the following method (i) or method (ii). By manufacturing, an electrolyte membrane having a water absorption rate in the above relationship can be obtained.
Specifically, the water absorption rate can be measured by the method described in Examples below.

The electrolyte membrane of the present invention, the power generation resistance that is measured by the method described in Examples below, preferably at most 200 milliohms · cm ² or less, more preferably 170mΩ · cm ² or less.

  The electrolyte membrane of the present invention is preferably a membrane whose dimensions do not easily change during the operation of the fuel cell or the like from the viewpoint of obtaining a fuel cell exhibiting stable power generation performance. The dimensional change rate in the hot water surface measured by the method described in the examples is preferably 40% or less, more preferably 30% or less.

  The thickness of the electrolyte membrane of the present invention may be the same as that of an electrolyte membrane usually used for fuel cells and the like, but is preferably 3 to 200 μm, more preferably 5 to 150 μm.

<Structure of hydrocarbon polymer electrolyte membrane>
The electrolyte membrane of the present invention may be a single electrolyte membrane or a hydrocarbon as long as the water absorption rate of at least one of the anode side layer and the cathode side layer is larger than the water absorption rate of adjacent layers. Although it may be a laminate having two or more layers made of a polymer, an electrolyte membrane having a plurality of layers having different water absorption rates can be easily formed, and in particular, the thickness of the anode-side outermost layer having a large water absorption rate can be reduced. The laminate is preferable from the viewpoint that it can be easily adjusted to the following range and the water absorption characteristics of the obtained electrolyte membrane can be easily adjusted.

  The electrolyte membrane of the present invention is not particularly limited, and a conventionally known membrane (layer) may be present in addition to the electrolyte membrane (layer), and the effects of the present invention can be more effectively exhibited. From this point, it is preferable that the polymer electrolyte membrane is a hydrocarbon-based polymer electrolyte substantially consisting only of an electrolyte membrane.

  The electrolyte membrane of the present invention has an anode side layer, a cathode side layer, an adjacent layer, an anode side outermost layer or a layer adjacent to the anode side outermost layer, and the like. For example, by performing the treatment of the following method (i), the treated portion is made into one layer, and the portion not subjected to the treatment is made into another layer, thereby forming a plurality of layers. It can be regarded as a film having.

  The laminate may be a laminate having two or more layers containing a hydrocarbon polymer, but two layers containing an ion exchange group-containing hydrocarbon polymer (hereinafter simply referred to as “polymer”). A laminate having at least one layer is preferable. The number of layers is not particularly limited, but if the number of layers is increased, peeling at the interface is more likely to occur. Therefore, a laminate composed of two or three layers is preferable from the viewpoint of suppressing the peeling. .

  In the laminate, the outermost layer and the layer in contact with the layer are substantially the same from the viewpoint that separation at the layer interface hardly occurs and an electrolyte membrane excellent in dimensional stability and mechanical strength is obtained. It is preferably a layer containing a polymer having a molecular structure, more preferably the two outermost layers are layers containing a polymer having substantially the same molecular structure, and all the layers in the laminate are More preferably, the layer includes a polymer having substantially the same molecular structure.

In order to give a difference between the water absorption rate of the outermost layer and the water absorption rate of the adjacent layer, polymers having different molecular structures and ion exchange amounts are used when forming the outermost layer and the adjacent layer. However, in this case, the layers of the obtained laminate tend to be easily separated.
On the other hand, for example, the electrolyte membrane obtained by the following method (ii) is excellent over a long period of time even when a polymer having substantially the same molecular structure is used when forming the outermost layer and its adjacent layer. The electrolyte membrane exhibits proton conductivity, and is unlikely to peel off at the layer interface, and is excellent in dimensional stability and mechanical strength.

Here, a polymer having substantially the same molecular structure means a polymer having the same repeating unit as well as a polymer having the completely same molecular structure, but having different repeating orders and content. Examples include coalescence.
The layers containing polymers having substantially the same molecular structure are usually preferable because delamination hardly occurs.

  The thickness of the outermost layer on the anode side of the laminate is preferably such that the dimensional change rate is not more than the above value, from the viewpoint of obtaining an electrolyte membrane that is superior in proton conductivity and dimensional stability over a long period of time. It is preferably 1 to 70% of the total thickness of the laminate, more preferably 2.5 to 25%, and even more preferably 3.5 to 15%.

<Method for producing hydrocarbon polymer electrolyte membrane>
The water absorption rate of the outermost layer of at least one of the anode side layer and the cathode side layer is larger than the water absorption rate of the adjacent layer. In particular, the water absorption rate of the anode outermost layer is larger than the water absorption rate of the adjacent layer. The method for producing the electrolyte membrane is not particularly limited, and a mixture containing a hydrocarbon polymer and a water absorbing agent (eg, silica gel, calcium chloride, activated carbon, activated alumina, silica alumina, magnesium silicate, copper sulfate) is used. It may be a method of forming a film so as to be unevenly distributed on one surface side in the electrolyte membrane from which the water absorbing agent is obtained by a conventionally known method (in this case, the layer in which the water absorbing agent is unevenly distributed and the other layer) The following method (i) is preferable.

  A laminate having a layer in which the water absorption rate of at least one of the anode side layer and the cathode side layer is larger than the water absorption rate of the adjacent layer, in particular, the water absorption rate of the anode side outermost layer is larger than the water absorption rate of the adjacent layer. The production method is not particularly limited, and is a method of laminating the layer containing the water-absorbing agent and the layer not containing the water-absorbing agent, and after forming one of these layers in advance, the other layer is formed on the layer. Although the method of apply | coating the mixture for formation and obtaining a laminated body etc. may be sufficient, the following method (ii) is preferable.

<Method (i)>
According to the method (i), an electrolyte membrane excellent in mechanical strength and free from peeling can be obtained.
Method (i) specifically includes:
A step (A) of bringing a solvent containing a good solvent for a polymer constituting the portion into contact with an outermost portion of a membrane to be a hydrocarbon-based polymer electrolyte membrane; and
Exposing the electrolyte membrane obtained in the step (A) to an atmosphere of water or a poor solvent for the polymer (B)
It is a method including.

・ Process (A)
The “film to be a hydrocarbon-based polymer electrolyte membrane” used in the step (A) refers to a raw material film in which the membrane obtained through the steps (A) and (B) becomes the electrolyte membrane of the present invention. .
The raw material film may be a film including a reinforcing layer obtained by impregnating or applying a reinforcing layer made of a porous material or a sheet-like fibrous substance with the following composition. Further, it may be a film containing a fiber, a filler-like reinforcing material, or the like.

  The raw material film is preferably formed in a step (C) of forming a coating film from a composition containing a polymer and a good solvent for the polymer, and the coating film obtained in the step (C) in the air or in a vacuum. It can be obtained by a method including the step (E) of heating.

Although the said process (C) is not specifically limited, The process of forming a coating film by specifically apply | coating the said composition on a base material by a well-known method is mentioned.
Examples of the base material include base materials such as resin, metal, and glass. Preferably, a base material made of a thermoplastic resin such as a polyethylene terephthalate (PET) film is used.

The polymer will be described below.
The polymer contained in the said composition can be used individually by 1 type or in combination of 2 or more types.

As a good solvent for the polymer contained in the composition, depending on the polymer used, for example, N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide, γ-butyrolactone, N, N— Aprotic polar solvents such as dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), dimethylurea, dimethylimidazolidinone, acetonitrile, etc., chlorinated solvents such as dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene and dichlorobenzene, methanol , Ethanol, propanol, iso-propyl alcohol, sec-butyl alcohol, tert-butyl alcohol and other alcohols, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl Alkylene glycol monoalkyl ethers such as ether, acetone, methyl ethyl ketone, cyclohexanone, ketones such as γ- butyrolactone, tetrahydrofuran (THF), ethers such as 1,3-dioxane.
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 and the viscosity of the resulting composition.

  When a mixture of an aprotic polar solvent and another solvent is used as the good solvent, the composition of the mixture is preferably 95 to 25% by weight of an aprotic polar solvent, more preferably 90 to 25%. % By weight and other solvents are preferably 5 to 75% by weight, more preferably 10 to 75% by weight (however, the total is 100% by weight). When the blending amount of the other solvent is within the above range, the effect of lowering 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 having an effect of lowering the viscosity of the composition in a wide composition range is preferable as the other solvent.

  The concentration of the polymer in the composition is preferably 1 to 40% by weight, more preferably 3 to 25%, depending on the molecular weight of the polymer and the thickness of the film or layer to be formed. % By weight. If the polymer content is less than the above range, pinholes tend to occur. On the other hand, when the content of the polymer exceeds the above range, the viscosity of the composition is too high to form a coating film, and the obtained electrolyte membrane may lack surface smoothness.

  In the composition, as long as the effects of the present invention are not impaired, a compound having a high platinum affinity (eg, a compound containing a sulfur atom), a metal-containing compound such as tin oxide or tin ion, and a metal ion, if necessary. You may mix | blend additives, such as at least 1 sort (s) of metal components chosen from the group which consists of.

  The composition further includes inorganic acids such as sulfuric acid and phosphoric acid; phosphoric acid glass; tungstic acid; phosphate hydrate; β-alumina proton substitute; inorganic proton conductor particles such as proton-introduced oxide; An organic acid containing an acid; an organic acid containing a sulfonic acid; an organic acid containing a phosphonic acid;

The step (E) is preferably a temperature at which the good solvent can be removed from the coating film obtained in the step (C), more preferably a temperature equal to or higher than the boiling point of the good solvent, specifically, 50 to 200 ° C. It is desirable to carry out by hold | maintaining at the temperature of 0.1 to 10 hours.
The heating may be performed in one step, or may be performed in two or more steps, that is, after preliminary drying in advance, followed by main drying.
The preliminary drying is preferably performed at 30 to 100 ° C, more preferably 50 to 100 ° C, preferably 3 to 180 minutes, more preferably 5 to 60 minutes.
Moreover, the said main drying can be preferably performed by hold | maintaining at the temperature more than the said preliminary drying temperature, More preferably, the temperature of 50-200 degreeC, Preferably it is 0.1 to 10 hours.

  When the obtained membrane is immersed in water after the preliminary drying or after the main drying, the organic solvent in the membrane can be replaced with water, and the amount of residual organic solvent in the resulting electrolyte membrane can be reduced. it can.

The amount of residual organic solvent in the electrolyte membrane thus obtained is usually 5% by weight or less. Further, depending on the immersion conditions, the amount of the remaining organic solvent in the obtained film can be reduced to 1% by weight or less. As such conditions, for example, the amount of water used relative to 1 part by weight of the membrane after preliminary drying or after main drying is 50 parts by weight or more, the temperature of the water when immersed is 10 to 60 ° C., and the immersion time 10 minutes to 10 hours.
Thus, after immersing a film | membrane in water, it is desirable to obtain a raw material film | membrane by air-drying.

  The base material may be peeled off after the preliminary drying or may be peeled off after the main drying. Further, it is a constituent material of a fuel cell and is laminated in contact with an electrolyte membrane, for example, when the following catalyst layer is used as the base material, the obtained raw material film is used without peeling from the base material. Also good.

  It does not restrict | limit especially as a solvent containing the good solvent of the polymer used by the said process (A), The solvent containing the solvent similar to the good solvent used for the said composition is mentioned. These good solvents can be used alone or in combination of two or more.

  In the step (A), the solvent containing the good solvent for the polymer is usually brought into contact with the entire surface of the raw material film having the largest area or a part thereof, and the solvent is brought into contact with both surfaces of the surface. However, it is preferable that the solvent is brought into contact with only one surface (the outermost portion on the anode side) from the viewpoint of obtaining an electrolyte membrane having more excellent proton conductivity.

  The method of bringing the solvent into contact with the outermost part of the raw material film is not particularly limited, and the method of applying the solvent to the layer by a conventionally known method, the method of spraying the solvent, and the outermost part of the raw material film as described above The method of immersing in a solvent is mentioned.

・ Process (B)
The step (B) is not particularly limited as long as it is a step in which the electrolyte membrane obtained in the step (A) is exposed to an atmosphere of water or a poor solvent of the polymer. Specifically,
Removing the good solvent from the electrolyte membrane obtained in the step (A) in an atmosphere of water or a poor solvent of the polymer, (B1), or
The step (B2) of removing the good solvent from the electrolyte membrane by immersing the electrolyte membrane obtained in the step (A) in water or a poor solvent of the polymer.
Is mentioned.

・ Process (B1)
Step (B1) is a step of removing the good solvent from the electrolyte membrane obtained in step (A) in an atmosphere of water or a poor solvent for the polymer. By passing through this step (B1), the water absorption rate of the outermost layer (part) is larger than the water absorption rate of the adjacent layer (part), preferably the water absorption rate of the anode outermost part is the water absorption rate of the adjacent portion A larger electrolyte membrane can be obtained.
Specifically, the step (B1) includes a method of heating the electrolyte membrane obtained in the step (A) in the presence of water vapor and / or the gaseous poor solvent.

  The poor solvent may be appropriately selected according to the polymer contained in the electrolyte membrane obtained in the step (A), but alcohols such as ethanol and n-butanol, esters such as butyl acetate, acetone, and methyl ethyl ketone And ketones such as propylene glycol monoethyl ether and propylene glycol monopropyl ether, and hydrocarbons such as hexane and toluene. This poor solvent can be used individually by 1 type or in combination of 2 or more types.

When the step (B1) is performed in an atmosphere in the presence of water vapor and / or gaseous poor solvent, the concentration of the water vapor or the poor solvent in the atmosphere is preferably 40% or more, more preferably 80% or more. Under the conditions of
In addition, the conditions which heat the electrolyte membrane obtained at the process (A) can be performed on the conditions similar to the conditions demonstrated by the said process (E), for example.

・ Process (B2)
Step (B2) is a step of removing the good solvent from the electrolyte membrane by immersing the electrolyte membrane obtained in the step (A) in water or a poor solvent of the polymer. By passing through this step (B2), the water absorption rate of the outermost layer (part) is larger than the water absorption rate of the adjacent layer (part), preferably the water absorption rate of the anode outermost part is the water absorption rate of the adjacent portion A larger electrolyte membrane can be obtained.
The immersion time and immersion conditions (temperature, etc.) at this time are not particularly limited.
Further, after the immersion, the obtained electrolyte membrane may be dried by air drying or heating under the same conditions as described in the step (E).

<Method (ii)>
According to the method (ii), the water absorption characteristics of the obtained electrolyte membrane can be easily adjusted.
Specifically, as the method (ii),
Method (1):
A step (A) of bringing a solvent containing a good solvent for a polymer constituting the layer into contact with an outermost layer of a membrane (laminate) to be a hydrocarbon-based polymer electrolyte membrane; and
Exposing the electrolyte membrane obtained in step (A) to an atmosphere of water or a poor solvent for the polymer (B)
Including, and
Method (2):
At least the anode outermost layer,
A step (C) of forming a coating film from a composition containing a polymer and a good solvent for the polymer; and
Step (D) in which the coating film obtained in Step (C) is exposed to an atmosphere of water or a poor solvent for the polymer.
The method of forming by the method containing is mentioned.

  In the method (1), a film (laminate) that becomes a hydrocarbon-based polymer electrolyte film is used instead of the raw material film in the method (i). This “membrane (laminate) to be a hydrocarbon-based polymer electrolyte membrane” is a raw material laminate in which the laminate obtained through the steps (A) and (B) in the method (1) is the electrolyte membrane of the present invention. It means the body.

The method for producing the raw material laminate is not particularly limited, but preferably,
A coating film is formed by performing the step (C) on the layer obtained through the steps (C) and (E) using the composition and using the same or different composition as the composition. Forming and obtaining a laminate through the step (E),
A method in which two or more layers are formed in advance through the steps (C) and (E), and the layers are superposed (heated), and the polymer constituting the layers is dissolved in these layers. Examples thereof include a method in which a solvent and the composition are applied (hot) pressing, or a method in which a conventionally known adhesive or crosslinking agent is applied between these layers (hot) pressing.

  This raw material laminate is a laminate containing a layer including a reinforcing layer, which is obtained by impregnating or applying a reinforcing layer made of a porous material or a sheet-like fibrous substance with the composition. It may be a body, or may be a laminate containing a layer containing fibers, filler-like reinforcing materials and the like.

The composition used for manufacturing the raw material laminate may contain a crosslinking agent.
As such a crosslinking agent, any crosslinking agent can be used as long as it can crosslink a layer containing a polymer. For example, a crosslinking agent having the following structure is preferable.

（式中Ｒ¹は水素または任意の有機基である。）

(Wherein R ¹ is hydrogen or an arbitrary organic group.)

  Specific examples of the cross-linking agent include RESITOP C357 (manufactured by Gunei Chemical Industry Co., Ltd.), DM-BI25X-F, 46DMOC, 46DMOIPP, 46DMOEP (trade name, manufactured by Asahi Organic Materials Co., Ltd.), DML. -MBPC, DML-MBOC, MDL-OCHP, DML-PC, DML-PCHP, DML-PTBP, DML-34X, DML-EP, DML-POP, DML-OC, dimethylol-Bis-C, dimethylol-BisOC-P , DML-BisOC-Z, DML-BisOCHP-Z, DML-PFP, DML-PSBP, DML-MB25, DML-MTrisPC, DML-Bis25X-34XL, DML-Bis25X-PCHP (trade name, Honshu Chemical Industry Co., Ltd.) ), "Nikarak" (registered trademark) MX-290 (trade) Product name, manufactured by Sanwa Chemical Co., Ltd.), 2,6-dimethoxymethyl-4-t-butylphenol, 2,6-dimethoxymethyl-p-cresol, 2,6-diacetoxymethyl-p-cresol, TriML-P , TriML-35XL, TriML-TrisCR-HAP (trade name, manufactured by Honshu Chemical Industry Co., Ltd.), TM-BIP-A (trade name, manufactured by Asahi Organic Materials Co., Ltd.), TML-BP, TML-HQ, TML-pp-BPF, TML-BPA, TMOM-BP (trade name, manufactured by Honshu Chemical Industry Co., Ltd.), “Nikarak” MX-280, “Nikarak” MX-270 (trade name, manufactured by Sanwa Chemical Co., Ltd.) ), HML-TPPHBA, HML-TPHAP (trade name, manufactured by Honshu Chemical Industry Co., Ltd.) and the like.

Specifically, the method (2) is for the surface of the film or laminate obtained by the same method as the material film or material laminate (the surface having the largest area among the outermost layers of the film or laminate). In this method, at least the anode outermost layer is formed on the whole or a part of at least one through the steps (C) and (D).
In the method (2), specifically, the step (C) and the step (D) may be performed on both surfaces of the surface of the film or laminate obtained by the same method as the raw material film or raw material laminate. However, it is preferable to perform the step (C) and the step (D) only on one surface (the outermost portion on the anode side) from the viewpoint of obtaining an electrolyte membrane having more excellent proton conductivity.

  The process (C) in this method (2) includes the same process as the process (C) in the process (A).

  When the composition used in step (C) in method (2) contains the cross-linking agent, the amount of the cross-linking agent used is most preferably from the viewpoint of easily obtaining an electrolyte membrane exhibiting the water absorption characteristics. The water absorption rate of the outer layer is a range that does not become smaller than the water absorption rate of the adjacent layer. Specifically, it is preferably 1 to 50 parts by weight with respect to 100 parts by weight of the polymer used in the composition, More preferably, it is 3 to 25 parts by weight.

The step (D) is not particularly limited as long as it is a step in which the coating film obtained in the step (C) is exposed to an atmosphere of water or a poor solvent for the polymer.
Removing the good solvent from the coating film obtained in the step (C) in an atmosphere of water or a poor solvent of the polymer (D1), or
The step (D2) of removing the good solvent from the coating film by immersing the coating film obtained in the step (C) in water or a poor solvent of the polymer.
Is mentioned.

  The steps (D1) and (D2) include the same steps as the steps (B1) and (B2) except that the object for removing the good solvent is changed to the coating film obtained in the step (C). Can be mentioned.

[Hydrocarbon polymer containing ion exchange groups]
The polymer has an ion exchange group.
The ion exchange group may be any known one, and is not particularly limited, and examples thereof include a phosphonic acid group and a sulfonic acid group. Especially, the electrolyte membrane which is excellent in power generation performance can be obtained by using the polymer which has a sulfonic acid group.

The glass transition temperature (Tg) of the polymer is 100 ° C. or higher, more preferably 120 ° C. or higher, particularly preferably 150 ° C. or higher, from the viewpoint that an electrolyte membrane having excellent durability can be obtained. The upper limit of the Tg is not particularly limited, but may be, for example, 250 ° C.
Specifically, the Tg can be measured by the method described in the examples below.

The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is preferably 10,000 to 1,000,000, more preferably 20,000 to 800,000, still more preferably 50,000 to 300,000. The number average molecular weight (Mn) is preferably 3,000 to 1,000,000, more preferably 6,000 to 800,000, and still more preferably 15,000 to 300,000.
Specifically, the average molecular weight can be measured by the method described in the Examples below.

The ion exchange capacity of the polymer is preferably 0.5 to 3.5 meq / g, more preferably 0.5 to 3.0 meq / g. 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 can be obtained. On the other hand, if it is 3.5 meq / g or less, it becomes an electrolyte membrane having sufficiently high water resistance, which is preferable.
Specifically, the ion exchange capacity of the polymer can be measured by the method described in the Examples below.

The ion exchange capacity can be adjusted by changing the type, ratio, combination, etc. of the structural units contained in the polymer. Therefore, it can be adjusted by changing the charge amount ratio, type, etc. of the precursor (monomer / oligomer) that induces the structural unit during the polymerization.
In general, when the proportion of the structural unit containing an ion exchange group increases in the polymer, the ion exchange capacity of the resulting polymer increases and proton conductivity increases, but the water resistance tends to decrease, When the proportion of the structural units is reduced, the ion exchange capacity of the resulting polymer is reduced and the water resistance is increased, but the proton conductivity tends to be lowered.

Examples of the polymer include aliphatic systems such as polyacetal, polyethylene, polypropylene, acrylic polymer, polystyrene, polystyrene-graft-ethylenetetrafluoroethylene copolymer, polystyrene-graft-polytetrafluoroethylene, and aliphatic polycarbonate. Polymer in which sulfonic acid group is introduced into polymer, polyester, polysulfone, polyphenylene ether, polyetherimide, aromatic polycarbonate, polyether ether ketone, polyether ketone, polyether ketone ketone, polyether ether sulfone, polyether sulfone , Polycarbonate, polyphenylene sulfide, aromatic polyamide, aromatic polyamideimide, aromatic polyimide, polybenzoxazole, polybenzothiazole Sulfonic acid aromatic polymer having an aromatic ring in a part or the whole of the main chain of polybenzimidazole or the like is introduced polymers.
Moreover, the polymer which changed the group introduce | transduced into these polymers into ion exchange groups, such as a phosphonic acid group from a sulfonic acid group, the polymer in which these groups coexist, etc. are mentioned.

  As the polymer, a known polymer can be used, and is not particularly limited. For example, International Publication No. 2013/018677, JP2012-067216, JP2007-284653, JP2008. Polymers described in JP-A Nos. 181882 and JP-A No. 2004-345997 are preferable, and the following polymer (1) is more preferable.

・ Polymer (1)
The polymer (1) is a polymer having a structural unit having an ion exchange group and a hydrophobic structural unit, and is a polymer or an oligomer.
In the present invention, the structural unit having an ion exchange group may be simply an ion exchange group, and examples of the ion exchange group include a sulfonic acid group, a phosphonic acid group, a carboxy group, and a bissulfonylimide group. Acid groups are preferred.

  Specifically, the polymer (1) is a polymer comprising a hydrophilic segment (A1) as a structural unit having an ion exchange group and a hydrophobic segment (B1) as a hydrophobic structural unit. Is preferred. In this case, the polymer (1) may be a block body or a random body, but from the viewpoint of obtaining an electrolyte membrane that is more excellent in power generation performance and dimensional stability during a dry and wet cycle. A block copolymer of a hydrophilic segment (A1) and a hydrophobic segment (B1) is preferred.

・ Hydrophilic segment (A1)
The hydrophilic segment (A1) is not particularly limited as long as it has an ion exchange group and shows hydrophilicity. For example, it has an aromatic ring in the main chain and contains an ion exchange group such as a sulfonic acid group. The structural unit represented by the following formula (5) (hereinafter referred to as “structural unit (5)” from the viewpoint that an electrolyte membrane having high continuity of the hydrophilic segment and high proton conductivity can be obtained. It is preferable that it is a segment including the structural unit (5).
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 (5), 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 carbonization 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 represent a hydrogen atom or a protecting group. However, at least one of all R ¹⁸ and R ¹⁹ contained in the structural unit (5) 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 (5) having a sulfonic acid group, as a structural unit having an ion exchange group other than the sulfonic acid group, for example, a structural unit having a phosphonic acid group, An aromatic structural unit having a nitrogen-containing heterocycle described in JP2011-089036A and WO2007 / 010731 may be included.

・ Hydrophobic segment (B1)
The hydrophobic segment (B1) is not particularly limited as long as it is a hydrophobic segment.
The hydrophilic segment (B1) may be composed of only one type of structural unit or may include two or more types of structural units.

  The hydrophobic segment (B1) is preferably a hydrophobic segment that has an aromatic ring in the main chain and does not contain an ion exchange group such as a sulfonic acid group, and an electrolyte membrane that is more excellent in suppressing hot water swelling is obtained. The structural unit represented by the following formula (1) (hereinafter also referred to as “structural unit (1)”) and the structural unit represented by the following formula (2) (hereinafter “structural unit (2)”) And a segment including at least one structural unit selected from the group consisting of structural units represented by the following formula (3 ′) (hereinafter also referred to as “structural unit (3 ′)”). Are preferable, and a segment composed of at least one structural unit selected from the group consisting of the structural unit (1) and the structural unit (2) is more preferable.

  When the polymer (1) contains any one of the structural units (1) to (3 ′), in particular, the structural unit (1) or (2), 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 (B1) contains a nitrile group, an electrolyte membrane with high toughness and mechanical strength can be produced.

・ Structural unit (1)
When the hydrophobic segment (B1) contains the structural unit (1), the segment (B1) includes the polymer (1) obtained by increasing the rigidity 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 (B1) may include one type of structural unit (1), or may include two or more types of structural units (1).

In the formula (1), 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 —. E- (E 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 heterocycle, 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 the group consisting of nitrile group, and R ²² -E-.) shows a plurality of R ²¹ is bonded To form a ring structure.
When R ²¹ is R ²² -E- and R ²² is further substituted with R ²² -E-, the plurality of E 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 (2)
It is preferable that the hydrophobic segment (B1) contains the structural unit (2) because radical resistance to peroxide and the like is improved and an electrolyte membrane excellent in power generation durability can be obtained.
Moreover, when the hydrophobic segment (B1) contains the structural unit (2), an appropriate flexibility (flexibility) can be imparted to the segment (B1), and the electrolyte membrane containing the resulting polymer Toughness can be improved.
The hydrophobic segment (B1) may include one type of structural unit (2), or may include two or more types of structural units (2).

In the formula (2), 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 —. E- (E and R ²² are each independently synonymous with E 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 (2) is a structural unit other than the structural unit represented by Formula (1).

・ Structural unit (3 ')
When the hydrophobic segment (B1) contains the structural unit (3 ′), an appropriate flexibility (flexibility) can be imparted to the segment (B1), and an electrolyte membrane containing the resulting polymer can be obtained. Toughness can be improved.
The hydrophobic segment (B1) may include one type of structural unit (3 ′) or may include two or more types of structural units (3 ′).

In formula (3 ′), A ′ and D ′ 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, an aromatic hydrocarbon group or a halogenated hydrocarbon group.), A cyclohexylidene group or a fluorenylidene group, B ′ independently represents an oxygen atom or a sulfur atom, and R ^{1 to} R ¹⁶ each independently represent represent hydrogen atom, halogen atom, hydroxy group, nitro group, nitrile group or R ²² -E- (E and R ²² are independently the same as E and R ²² in the formula (1).) shows the , R ^{1 to} R ¹⁶ may combine 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.

-Synthesis method of polymer (1) The polymer (1) 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 an ion exchange 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.

≪Membrane-electrode assembly≫
The membrane-electrode assembly of the present invention is, for example, a laminate 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 cathode electrode catalyst layer is provided on one surface of the electrolyte membrane of the present invention, and an anode electrode catalyst layer is provided on the other surface. It is preferable that a gas diffusion layer is provided in contact with the opposite side of each catalyst layer to the electrolyte membrane.

  The gas diffusion layer is not particularly limited and a known one can be used, and examples thereof 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 substrate 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.

  Although the thickness of the said gas diffusion layer should just be the same thickness as the gas diffusion layer normally used for a fuel cell, Preferably it is 50-400 micrometers, More preferably, it is 100-300 micrometers.

The catalyst layer is not particularly limited, and a known layer can be used. For example, the catalyst layer includes a catalyst, an ion exchange resin electrolyte, and the like.
As the catalyst, a noble metal catalyst such as platinum, palladium, gold, ruthenium or iridium is preferably used. The noble metal catalyst may contain two or more elements such as an alloy or a mixture. As such a precious metal catalyst, a catalyst supported on high specific surface area carbon fine particles may be used.

  The ion exchange resin electrolyte acts as a binder component for binding the catalyst, and efficiently supplies ions generated by the 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 electrolyte is preferably a polymer having a proton exchange group in order to improve proton conductivity in the catalyst layer. Examples of proton exchange groups include, but are not particularly limited to, sulfonic acid groups, carboxylic acid groups, and phosphoric acid groups.

The polymer having such a proton exchange group is not particularly limited, but a polymer having a proton exchange group composed of a fluoroalkyl ether side chain and a fluoroalkyl main chain, or an aromatic hydrocarbon-based polymer having a sulfonic acid group. A coalescence or the like is preferably used. Further, the ion exchange group-containing hydrocarbon polymer may be used as an ion exchange resin electrolyte, and further, a polymer having a proton exchange group and containing a fluorine atom, another polymer obtained from ethylene, styrene, etc. These copolymers or blends may be used.
Moreover, the said ion exchange resin electrolyte can use a well-known thing without a restriction | limiting in particular, For example, Nafion may be sufficient.

  The catalyst layer may further contain an additive such as a carbon fiber or a resin having no 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.

  Although the thickness of the said catalyst layer should just be the same thickness as the catalyst layer normally used for a fuel cell etc., Preferably it is 1-100 micrometers, More preferably, it is 3-50 micrometers.

≪Fuel cell≫
The fuel cell of the present invention includes the membrane-electrode assembly. Such a fuel cell is particularly excellent in power generation and durability, suppresses a decrease in power generation performance over time, and enables stable power generation over a long period of time.

  Specifically, the fuel cell includes at least one electricity generation unit including a separator, located on both outer sides of at least one membrane-electrode assembly; a fuel supply unit that supplies fuel to the electricity generation unit; and oxidation Preferably, the fuel cell includes an oxidant supply unit that supplies the agent to the electricity generation unit.

  As said separator, what is used for a normal fuel cell can be used. Specifically, a carbon type separator, a metal type separator, etc. are mentioned.

  Moreover, as a member which comprises a fuel cell, it is possible to use a well-known thing without a restriction | limiting in particular. The fuel cell 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 flat stacking in which single cells are arranged in a plane, and a fuel or oxidant flow path is a stack in which single cells are stacked via separators formed on the back surface of the separator. Polar stacking may be used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

  Hereinafter, evaluation of the compounds obtained in the synthesis examples was performed as follows.

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

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

[Synthesis Example 1]
Synthesis of hydrophilic unit 3,5-Dichlorobenzenesulfonyl chloride (114.65 g, 467 mmol) was added to a solution of neopentyl alcohol (45.30 g, 514 mmol) in pyridine (300 mL) over 15 minutes while stirring little by little. did. During this time, the reaction temperature was kept at 18-20 ° C. The reaction mixture was stirred for an additional 30 minutes while cooling, and then ice-cooled 10 wt% aqueous HCl (1600 mL) was added. Insoluble components in water were extracted with 700 mL of ethyl acetate, washed twice with 1N HCl aqueous solution (700 mL each), then twice with 5 wt% aqueous NaHCO ₃ solution (700 mL each) and dried over MgSO ₄ . . The solvent was removed using a rotary dryer and the residue was recrystallized from 500 mL methanol. As a result, neopentyl 3,5-dichlorobenzenesulfonate represented by the formula (1-1) was obtained as glossy colorless crystals (purity exceeding 99% by ¹ H-NMR). The yield was 105.98 g, and the yield was 76%.

[Synthesis Example 2]
Synthesis of hydrophobic oligomer To a 1 L three-necked flask equipped with a stirrer, thermometer, Dean-stark tube, nitrogen inlet tube and condenser tube, 90.1 g (0.52 mol) of 2,6-dichlorobenzonitrile, 2, 26.6 g (0.12 mol) of 5-di-tert-butylhydroquinone, 59.4 g (0.36 mol) of 2-tert-butylhydroquinone, and 85.6 g (0.62 mol) of potassium carbonate were weighed. After the flask was purged with nitrogen, 600 mL of sulfolane and 300 mL of toluene were added and stirred. After stirring, the obtained flask was placed in an oil bath, and the reaction solution was heated to reflux at 150 ° C. Water produced by the reaction was trapped in a Dean-stark tube. After 3 hours, when almost no water was observed, toluene was removed from the Dean-stark tube out of the system. The reaction temperature was gradually raised to 180 to 190 ° C., and stirring was continued at that temperature for 3 hours. Then, 24.6 g (0.14 mol) of 2,6-dichlorobenzonitrile was added, and the reaction was further continued for 5 hours.

  The reaction solution was allowed to cool and then coagulated in 2401 mL of a methanol / 4 wt% aqueous sulfuric acid solution (5/1 (volume ratio)). The precipitated product was filtered and the filtrate was placed in 2401 mL of water and stirred at 55 ° C. for 1 hour. After filtration, the filtrate was again placed in 2401 mL of water and stirred at 55 ° C. for 1 hour. After filtration, the filtrate was put into 2401 mL of methanol and stirred at 55 ° C. for 1 hour, and then filtered. The filtrate was again put into 2401 mL of methanol, stirred at 55 ° C. for 1 hour and filtered. The filtered product was air-dried and then vacuum-dried at 80 ° C. to obtain 125 g of the desired product (yield 90%). Mn measured by GPC was 7,000 and Mw 15000. It was confirmed that the obtained compound was an oligomer represented by the formula (1-2).

[Synthesis Example 3]
Synthesis of sulfonic acid group-containing polymer (I) Compound 289.57 g represented by formula (1-1), compound 164.22 g represented by formula (1-2), bis (triphenylphosphine) nickel dichloride In a mixture of 26.17 g, triphenylphosphine 20.98 g, and zinc 156.89 g, 1448.3 mL of dry dimethylacetamide (DMAc) was added under nitrogen.

The reaction system was heated with stirring (finally heated to 79 ° C.) and reacted for 3 hours. An increase in viscosity in the system was observed during the reaction. The obtained reaction solution was diluted with 2510 mL of DMAc, stirred for 30 minutes, and filtered using Celite as a filter aid.
To the filtrate was added 423.11 g of lithium bromide, and the mixture was reacted at an internal temperature of 120 ° C. for 7 hours under a nitrogen atmosphere. After the reaction, the reaction solution was cooled to room temperature, poured into 35 L of water and solidified. The coagulated product was immersed in acetone, filtered, and the filtrate was washed. The washed product was washed with stirring in 7658 g of 1N aqueous sulfuric acid. After filtration, the product was washed with ion exchanged water until the pH of the washing solution reached 5 or higher. Mn of the obtained polymer was 52000, Mw was 120,000, and the ion exchange capacity was 2.6 meq / g. The obtained polymer was a compound represented by the following formula.

[Synthesis Example 4]
Synthesis of sulfonic acid group-containing polymer (II) Compound 2910.2 g represented by formula (1-1), compound 13.3.03 g represented by formula (1-2), bis (triphenylphosphine) nickel dichloride 26 1272 mL of dried DMAc in a mixture of .17 g, 20.98 g of triphenylphosphine, and 156.89 g of zinc was added under nitrogen.

The reaction system was heated with stirring (finally heated to 79 ° C.) and reacted for 3 hours. An increase in viscosity in the system was observed during the reaction. The obtained reaction solution was diluted with 2299 mL of DMAc, stirred for 30 minutes, and filtered using Celite as a filter aid.
425.22 g of lithium bromide was added to the filtrate, and the mixture was reacted at an internal temperature of 120 ° C. for 7 hours under a nitrogen atmosphere. After the reaction, the reaction solution was cooled to room temperature, poured into 32 L of water and solidified. The coagulated product was immersed in acetone, filtered, and the filtrate was washed. The washed product was washed with stirring in 7063 g of 1N aqueous sulfuric acid. After filtration, the product was washed with ion exchanged water until the pH of the washing solution reached 5 or higher. Mn of the obtained polymer was 58000, Mw was 130,000, and the ion exchange capacity was 2.9 meq / g. The obtained polymer was a compound represented by the following formula.

[Evaluation method]
(1) <Hot water surface dimensional change, presence / absence of peeling of laminated film interface, evaluation of water absorption>
The electrolyte membranes obtained in the following examples and comparative examples were cut into 2.0 cm × 3.0 cm to obtain test pieces. The obtained test piece was conditioned under conditions of 24 ° C. and relative humidity (RH) 50%, and then the weight of the test piece (initial weight) was measured. The test piece was placed in a 150 mL vial, and about 100 mL was placed there. Of deionized water was added, and the mixture was heated at 95 ° C. for 24 hours using a thermostatic dryer (manufactured by ASONE, SONW-450). After heating, the test piece was taken out from the hot water, and the in-plane dimensional change rate was determined from the following formula.
In-plane dimensional change rate (%) = (size of 2 cm side when containing water / 2 cm + size of 3 cm side when containing water / 3 cm) × 100/2

  Moreover, when the said test piece was taken out from hot water after completion | finish of the said heating, the presence or absence of peeling of the lamination | stacking interface of an electrolyte membrane (laminated film) was confirmed visually.

The water absorption (%) of each layer of the electrolyte membrane obtained in the following examples and comparative examples was measured as follows.
Except for cast coating on a PET substrate so that the film thickness obtained is 20 μm, the substrate with an electrolyte membrane was formed in the same manner as each layer constituting the electrolyte membrane obtained in the following Examples and Comparative Examples. Created. That is, for example, in order to measure the water absorption rate of each layer of the electrolyte membrane of Example 1, the substrate with an electrolyte membrane having a thickness of 20 μm containing the polymer (I) and the electrolyte membrane having a thickness of 20 μm containing the polymer (II) A base material was prepared.
Next, the electrolyte membrane was peeled from the obtained substrate with electrolyte membrane, and the peeled electrolyte membrane was cut into 2.0 cm × 3.0 cm to obtain a test piece. The obtained test piece was conditioned under conditions of 24 ° C. and relative humidity (RH) 50%, and then the weight of the test piece (initial weight) was measured. The test piece was placed in a 150 mL vial, and about 100 mL was placed there. Of deionized water was added, and the mixture was heated at 95 ° C. for 24 hours using a thermostatic dryer (manufactured by ASONE, SONW-450). After completion of heating, the test piece was taken out from the hot water, the water on the surface of the test piece was lightly wiped with Kimwipe, and the weight of the test piece after immersion in hot water (weight after water absorption) was measured. The water absorption was calculated from the following formula.
Water absorption rate (%) = (weight after water absorption / initial weight) × 100

  The water absorption rate does not change with the thickness of the electrolyte membrane.

(2) <Generation resistance measurement>
[Preparation of base layer paste for gas diffusion layer]
80 g of zirconia balls ("YTZ balls" manufactured by Nikkato Co., Ltd.) with a diameter of 5 mm are placed in an 80 mL plastic bottle, 0.48 g of ketjen black EC (manufactured by Lion Corporation), 12.21 g of distilled water, n-propyl alcohol 4 .14 g and 3.16 g of Nafion (registered trademark) D2020 (manufactured by DuPont, polymer concentration 21% dispersion, ion exchange capacity 1.08 meq / g) are stirred for 60 minutes with a paint shaker, and then the zirconia balls are removed. Thus, an underlayer paste for the gas diffusion layer was obtained.

[Preparation of anode catalyst layer paste]
80 g of zirconia balls (YTZ balls) with a diameter of 5 mm are put into an 80 mL plastic bottle, and platinum ruthenium-supported carbon particles (“TEC61E54” manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., Pt: 29.8 mass% supported, Ru: 23.2 mass%) Support) 1.23 g, distilled water 3.49 g, n-propyl alcohol 11.59 g and Nafion D2020 (3.69 g) were added, and the mixture was stirred for 60 minutes with a paint shaker. Obtained.

[Preparation of cathode catalyst layer paste]
Next, 80 g of zirconia balls (YTZ balls) having a diameter of 5 mm are put into an 80 mL plastic bottle, and platinum-supported carbon particles (“TEC10E50E” manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., Pt: 45.6% by mass) 1.18 g, distilled 3.46 g of water, 11.26 g of n-propyl alcohol and Nafion D2020 (4.09 g) were added, and the mixture was stirred for 60 minutes with a paint shaker, and then zirconia balls were removed to obtain a cathode electrode paste.

[Preparation of anode side catalyst layer]
A gas diffusion layer GDL34EE manufactured by SGL CARBON was cut into 5 cm × 5 cm, and the base layer paste of the gas diffusion layer was applied on the microporous layer side and dried at 120 ° C. for 60 minutes. The carrying amount of the underlayer was 0.30 mg / cm ² . Further, an anode catalyst layer paste was applied on the underlayer and dried at 120 ° C. for 60 minutes. The amount of catalyst applied was 0.50 mg / cm ² .

[Production of cathode-side catalyst layer]
A gas diffusion layer GDL34EE manufactured by SGL CARBON was cut into 5 cm × 5 cm, and the base layer paste of the gas diffusion layer was applied on the microporous layer side and dried at 120 ° C. for 60 minutes. The carrying amount of the underlayer was 0.30 mg / cm ² . Further, a cathode catalyst layer paste was applied on the underlayer and dried at 120 ° C. for 60 minutes. The amount of catalyst applied was 0.50 mg / cm ² .

[Production of polymer electrolyte fuel cells]
The electrolyte membranes obtained in the following examples and comparative examples are the anode-side catalyst layer-attached gas diffusion layer and the cathode-side catalyst layer-attached gas diffusion layer, and the catalyst layer paste application surface of each gas diffusion layer is in contact with the electrolyte membrane. The membrane-electrode assembly was manufactured by hot pressing at 160 ° C. for 10 minutes under a pressure of 60 kg / cm ² . A separator also serving as a gas flow path is laminated on the gas diffusion layer of the obtained membrane-electrode assembly, which is sandwiched between two titanium current collectors, and a heater is disposed on the outside thereof, with an effective area of 25 cm. ^Two evaluation fuel cells were prepared.
However, when the electrolyte membrane is sandwiched between the gas diffusion layers, as shown in Table 1, in Examples 1 to 3, and Comparative Examples 1 and 2, the anode side catalyst layer is disposed on the second membrane side of the electrolyte membrane. The attached gas diffusion layer was in contact.

[Measurement of power generation resistance]
Air was supplied to the cathode electrode side of the obtained fuel cell for evaluation at a utilization rate of 40%, pure hydrogen was supplied to the anode electrode side at a utilization rate of 53%, the cell temperature was 80 ° C., and the relative humidity on the cathode electrode side was 0. %, The anode electrode side relative humidity was 43%, and the cell resistance after holding for 12 hours at a current density of 0.25 A / cm ² was measured.

[Example 1]
A solution obtained by dissolving 10 g of the polymer (I) obtained in Synthesis Example 3 in 57 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) was cast-coated on a PET film with a die coater, and 80 ° C. in the atmosphere. And dried for 40 minutes at 120 ° C. in the atmosphere. 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 PET film with an electrolyte film having a film thickness of 19 μm (first layer film) Got. Further, a solution obtained by dissolving 1 g of the polymer (II) obtained in Synthesis Example 4 in 24 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) was cast-coated on the first layer film with a bar coater. After drying in the atmosphere at 80 ° C. for 40 minutes, it was dried in the atmosphere 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 the remaining NMP in the coating film, and then air-dried, and an electrolyte membrane having a total film thickness of 20 μm (first layer film + second layer) A PET film with a film) was obtained. It was found that the thickness of the second layer film was 1 μm by subtracting the thickness of the first layer film from the total thickness of the obtained electrolyte membrane. Evaluation of said (1)-(2) was implemented using the electrolyte membrane obtained by peeling a PET film from the obtained PET film with electrolyte membrane. The results are shown in Table 1.

[Example 2]
A solution obtained by dissolving 10 g of the polymer (I) obtained in Synthesis Example 3 in 57 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) was cast-coated on a PET film with a die coater, and 80 ° C. in the atmosphere. And dried for 40 minutes at 120 ° C. in the atmosphere. 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 PET film with an electrolyte film having a film thickness of 19 μm (first layer film) Got. Further, a solution obtained by dissolving 1 g of the polymer (I) obtained in Synthesis Example 3 in 24 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) was cast-coated on the first layer film with a bar coater. After drying at 80 ° C. and a relative humidity of 90% RH for 40 minutes, it was dried at 120 ° C. in the atmosphere for 40 minutes. The dried PET film with a coating film was immersed in a large amount of distilled water overnight to remove residual NMP in the coating film, and then air-dried to obtain a PET film with an electrolyte film having a total film thickness of 20 μm. It was found that the thickness of the second layer film was 1 μm by subtracting the thickness of the first layer film from the total thickness of the obtained electrolyte membrane. Evaluation of said (1)-(2) was implemented using the electrolyte membrane obtained by peeling a PET film from the obtained PET film with electrolyte membrane. The results are shown in Table 1.

Example 3
A solution obtained by dissolving 10 g of the polymer (I) obtained in Synthesis Example 3 in 57 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) was cast-coated on a PET film with a die coater, and 80 ° C. in the atmosphere. And dried for 40 minutes at 120 ° C. in the atmosphere. 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 PET film with an electrolyte film having a film thickness of 19 μm (first layer film) Got. Further, a solution obtained by dissolving 1 g of the polymer (I) obtained in Synthesis Example 3 in 24 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) was cast-coated on the first layer film with a bar coater. The coated PET film was immersed in distilled water for 5 minutes and then dried at 120 ° C. in the atmosphere for 40 minutes. The dried PET film with a coating film was immersed in a large amount of distilled water overnight to remove residual NMP in the coating film, and then air-dried to obtain a PET film with an electrolyte film having a total film thickness of 20 μm. It was found that the thickness of the second layer film was 1 μm by subtracting the thickness of the first layer film from the total thickness of the obtained electrolyte membrane. Evaluation of said (1)-(2) was implemented using the electrolyte membrane obtained by peeling a PET film from the obtained PET film with electrolyte membrane. The results are shown in Table 1.

Example 4
A solution obtained by dissolving 1 g of the polymer (I) obtained in Synthesis Example 3 in 24 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) was cast-coated on a PET film with a bar coater. After immersing the PET film in distilled water for 5 minutes, the PET film with an electrolyte membrane having a film thickness of 1 μm (first layer film) was obtained by drying at 120 ° C. for 40 minutes in the air. Further, on the first layer film, a solution obtained by dissolving 10 g of the polymer (I) obtained in Synthesis Example 3 in 57 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) was cast coated with a die coater. After drying in the atmosphere at 80 ° C. for 40 minutes, it was dried in the atmosphere 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 total film thickness is 19 μm and the thickness of the second layer film is 18 μm. A PET film with an electrolyte membrane was obtained. Furthermore, a solution obtained by dissolving 1 g of the polymer (I) obtained in Synthesis Example 3 in 24 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) (mass ratio) was placed on the second layer film with a bar coater. After cast coating, the coated PET film was immersed in distilled water for 5 minutes, and then dried in air 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 residual NMP in the coating film, and then air-dried to obtain a PET film with an electrolyte film having a total film thickness of 20 μm. The thickness of the third layer film was found to be 1 μm by subtracting the thickness of the first and second layer films from the total thickness of the obtained electrolyte membrane. Evaluation of said (1)-(2) was implemented using the electrolyte membrane obtained by peeling a PET film from the obtained PET film with electrolyte membrane. The results are shown in Table 1.

Example 5
A solution obtained by dissolving 10 g of the polymer (I) obtained in Synthesis Example 3 in 57 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) was cast-coated on a PET film with a die coater, and 80 ° C. in the atmosphere. And dried for 40 minutes at 120 ° C. in the atmosphere. 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 PET film with an electrolyte film having a film thickness of 19 μm (first layer film) Got. Further, a solution obtained by dissolving 1 g of the polymer (II) obtained in Synthesis Example 4 and 0.05 g of p-xylene glycol as a crosslinking agent in 24 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) was used as the one layer. The cast film was cast on the eye coat with a bar coater, dried in air at 80 ° C. for 40 minutes, and then dried in air at 120 ° C. for 40 minutes. The dried PET film with a coating film is immersed overnight in a large amount of distilled water to remove the remaining NMP in the coating film, and then heated at 160 ° C. in the atmosphere for 30 minutes for a crosslinking reaction. The total film thickness is 20 μm. A PET film with an electrolyte membrane was obtained. It was found that the thickness of the second layer film was 1 μm by subtracting the thickness of the first layer film from the total thickness of the obtained electrolyte membrane. Evaluation of said (1)-(2) was implemented using the electrolyte membrane obtained by peeling a PET film from the obtained PET film with electrolyte membrane. The results are shown in Table 1.

[Comparative Example 1]
A solution obtained by dissolving 10 g of the polymer (I) obtained in Synthesis Example 3 in 57 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) was cast-coated on a PET film with a die coater, and 80 ° C. in the atmosphere. And dried for 40 minutes at 120 ° C. in the atmosphere. 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 PET film with an electrolyte film having a film thickness of 19 μm (first layer film) Got. Further, a solution obtained by dissolving Nafion D2020 (10 g) in 42 g of n-propyl alcohol was cast-coated on the first layer film with a bar coater, dried at 80 ° C. for 40 minutes in the atmosphere, and then at 120 ° C. in the atmosphere. It dried for 40 minutes and obtained PET film with an electrolyte membrane whose total film thickness is 20 micrometers. It was found that the thickness of the second layer film was 1 μm by subtracting the thickness of the first layer film from the total thickness of the obtained electrolyte membrane. Evaluation of said (1)-(2) was implemented using the electrolyte membrane obtained by peeling a PET film from the obtained PET film with electrolyte membrane. The results are shown in Table 1.

[Comparative Example 2]
A solution obtained by dissolving 10 g of the polymer (I) obtained in Synthesis Example 3 in 57 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) was cast-coated on a PET film with a die coater, and 80 ° C. in the atmosphere. And dried for 40 minutes at 120 ° C. in the atmosphere. 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 PET film with an electrolyte film having a film thickness of 19 μm (first layer film) Got. Further, 1 g of the polymer (II) obtained in Synthesis Example 4 and 0.15 g of p-xylene glycol as a crosslinking agent were dissolved in 24 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) (mass ratio). Was coated on the first layer film with a bar coater, dried in air at 80 ° C. for 40 minutes, and then dried in air at 120 ° C. for 40 minutes. The dried PET film with a coating film is immersed overnight in a large amount of distilled water to remove the remaining NMP in the coating film, and then heated at 160 ° C. in the atmosphere for 30 minutes for a crosslinking reaction. The total film thickness is 20 μm. A PET film with an electrolyte membrane was obtained. It was found that the thickness of the second layer film was 1 μm by subtracting the thickness of the first layer film from the total thickness of the obtained electrolyte membrane. Evaluation of said (1)-(2) was implemented using the electrolyte membrane obtained by peeling a PET film from the obtained PET film with electrolyte membrane. The results are shown in Table 1.

[Comparative Example 3]
A solution obtained by dissolving 10 g of the polymer (I) obtained in Synthesis Example 3 in 57 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) was cast-coated on a PET film with a die coater, and 80 ° C. in the atmosphere. And dried for 40 minutes at 120 ° C. in the atmosphere. The dried PET film with a coating film was immersed in a large amount of distilled water overnight to remove residual NMP in the coating film, and then air-dried to obtain a PET film with an electrolyte film having a film thickness of 20 μm. Evaluation of said (1)-(2) was implemented using the electrolyte membrane obtained by peeling a PET film from the obtained PET film with electrolyte membrane. The results are shown in Table 1.

[Comparative Example 4]
A solution of 5 g of the polymer (I) obtained in Synthesis Example 3 and 5 g of the polymer (II) obtained in Synthesis Example 4 in 57 g of a mixed solvent of methanol / NMP = 40/60 (mass ratio) It was cast-coated on a die coater and dried in the atmosphere at 80 ° C. for 40 minutes, and then dried in the atmosphere 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 residual NMP in the coating film, and then air-dried to obtain a PET film with an electrolyte film having a film thickness of 20 μm. Evaluation of said (1)-(2) was implemented using the electrolyte membrane obtained by peeling a PET film from the obtained PET film with electrolyte membrane. The results are shown in Table 1.

Claims (12)

  A hydrocarbon-based polymer electrolyte membrane disposed between an anode and a cathode, wherein the water absorption rate of at least one of the anode side layer and the cathode side layer of the polymer electrolyte membrane is equal to the water absorption rate of an adjacent layer. A hydrocarbon-based polymer electrolyte membrane characterized by being larger than the rate.   The hydrocarbon-based polymer electrolyte membrane according to claim 1, wherein the water absorption rate of the outermost layer on the anode side of the polymer electrolyte membrane is larger than the water absorption rate of a layer adjacent thereto.   The hydrocarbon-based polymer electrolyte membrane according to claim 1 or 2, wherein a difference between the water absorption rate of the anode side outermost layer of the polymer electrolyte membrane and the water absorption rate of a layer adjacent thereto is 5% or more.   The hydrocarbon polymer electrolyte membrane according to any one of claims 1 to 3, wherein the polymer electrolyte membrane is a laminate having two or more layers containing an ion exchange group-containing hydrocarbon polymer.   5. The layered body according to claim 4, wherein at least one outermost layer and a layer in contact with the layer are layers containing an ion exchange group-containing hydrocarbon polymer having substantially the same molecular structure. Hydrocarbon polymer electrolyte membrane. Of the polymer electrolyte membrane, at least the anode outermost layer is
A step (C) of forming a coating film from a composition containing an ion exchange group-containing hydrocarbon polymer and a good solvent for the polymer; and
Step (D) in which the coating film obtained in Step (C) is exposed to an atmosphere of water or a poor solvent for the polymer.
The hydrocarbon-based polymer electrolyte membrane according to any one of claims 1 to 5, which is a layer obtained by a method comprising: Among the polymer electrolyte membranes, at least the anode-side outermost layer contains an ion exchange group-containing hydrocarbon polymer, and the outermost layer comprises:
A step of bringing the outermost part or outermost layer of the membrane to be the polymer electrolyte membrane into contact with a solvent containing a good solvent for the ion-exchange group-containing hydrocarbon-based polymer constituting the part or layer (A), and
Exposing the polymer electrolyte membrane obtained in step (A) to an atmosphere of water or a poor solvent for the polymer (B)
The hydrocarbon-based polymer electrolyte membrane according to any one of claims 1 to 5, which is a layer obtained by a method comprising:   The hydrocarbon-based polymer electrolyte membrane according to any one of claims 4 to 7, wherein the thickness of the outermost layer on the anode side of the laminate is 1 to 70% of the total thickness of the laminate. Among the polymer electrolyte membranes, at least the cathode-side outermost layer is
A step (C) of forming a coating film from a composition containing an ion exchange group-containing hydrocarbon polymer and a good solvent for the polymer; and
The hydrocarbon system according to any one of claims 1 to 8, which is a layer obtained by a method comprising the step (E) of heating the coating film obtained in the step (C) in air or under vacuum. Polymer electrolyte membrane.   The hydrocarbon-based polymer electrolyte membrane according to claim 6 or 9, wherein the composition contains a crosslinking agent.   A membrane-electrode assembly in which a gas diffusion layer, a catalyst layer, the hydrocarbon-based polymer electrolyte membrane according to any one of claims 1 to 10, a catalyst layer, and a gas diffusion layer are laminated in this order.   A fuel cell comprising the membrane-electrode assembly according to claim 11.