JP5031340B2 - Membrane-electrode assembly - Google Patents

Description

  The present invention relates to an electrode-solid polymer membrane assembly used in a polymer electrolyte fuel cell or the like.

  A fuel cell is configured as a unit of a cell in which an anode and a cathode electrode in which a reaction responsible for power generation occurs and an electrolyte serving as an ion conductor between the anode and the cathode electrode are sandwiched between separators.

  The electrode actually becomes an electrochemical reaction field, and an electrode base material for promoting gas diffusion and collecting current is usually joined to the surface. For example, in an anode electrode of a polymer electrolyte fuel cell, fuel gas reacts on the electrode surface to generate protons and electrons, and the electrons are conducted to the electrode substrate, and the protons are conducted to the proton exchange membrane of the electrolyte. On the other hand, in the cathode electrode, the oxidizing gas, protons conducted from the electrolyte, and electrons conducted from the electrode substrate react to generate water on the electrode surface.

  Therefore, the anode electrode is required to have good electron conductivity and proton conductivity, and the cathode electrode has good electron conductivity and proton conductivity, and the generated water can be efficiently discharged. It is requested. In order to improve the electron conductivity and proton conductivity, a structure in which the carbon in the electrode and the electrolyte are continuously connected is necessary.

  In a conventional electrode formed by applying an electrode paste to a substrate, a composition distribution may be formed in the thickness direction of the electrode depending on the viscosity, composition, composition type, substrate type and the like of the electrode paste. Specifically, the electrode on the electrode substrate side tends to be dense. For this reason, distribution occurs in the reaction at the electrode, but the conventional electrode does not consider such a phenomenon, so gas diffusivity or water discharge that affects the reaction efficiency, and electron conductivity Or it could not be said that the compatibility with proton conductivity was sufficient.

Moreover, as an example of controlling the electrolyte distribution and pore volume in the electrode, in Japanese Patent Laid-Open No. 2001-319663 (Patent Document 1) and WO01 / 022514 (Patent Document 2), the electrolytic mass in the thickness direction of the electrode is expressed as gas. It is described that by controlling the diffusion layer side to be small and the proton exchange membrane side to be large, the gas diffusion property of the gas diffusion layer side electrode is improved and the power generation performance is improved. However, since the gradient range of the electrolytic mass is not described and there is no description that actually confirms the distribution of the electrolytic mass in the electrode, the effect of the gradient of the electrolytic mass is unclear. In addition, if the electrolytic mass in the electrode on the proton exchange membrane side is too large, the pore volume will be reduced, so that the electrode layer on the proton exchange membrane side may have insufficient gas diffusibility and drainage, and the electron conduction path may be cut off. On the other hand, if the electrolytic mass in the electrode on the gas diffusion layer side is made small, the continuity of the proton conduction path from the proton exchange membrane to the gas diffusion layer becomes insufficient in the electrode catalyst layer on the gas diffusion layer side. there is a possibility. Therefore, in the prior art, since the electrolyte distribution and pore volume distribution in the catalyst layer cannot be sufficiently controlled, the power generation performance and the power generation durability are not sufficient.
JP 2001-319663 A WO01 / 022514

An object of the present invention is to provide a membrane-electrode assembly having an electrode with improved power generation performance and power generation durability.

  The present inventors diligently studied the method for improving the power generation performance and the power generation durability. As a result, the pore volume in the thickness direction in the electrode and the distribution state of the polymer electrolyte in the membrane-electrode assembly are the power generation performance and We found that this is one of the factors that have a large impact on power generation durability, specified the range of the distribution state in each thickness direction, and made it closer to be uniform in the thickness direction of the electrode, and if necessary By using polyarylene having a sulfonic acid group having high heat resistance as the polymer electrolyte, it was found that the power generation performance and the power generation durability were further improved even in a high temperature region, and the present invention was completed.

According to the present invention, the following membrane-electrode assemblies [1] to [8] and a method for producing the same are provided, and the object of the present invention is achieved.
[1] A membrane-electrode assembly having an ion conductive membrane and an anode electrode and a cathode electrode each containing catalyst particles and a polymer electrolyte on both sides of the ion conductive membrane,
At least one of the anode electrode and the cathode electrode, in the thickness direction from the electrode surface to the ion conductive membrane side, with respect to the pore volume (V1) in the electrode up to 50% of the total electrode weight, the ion conductive membrane side The ratio (V2 / V1) of pore volume (V2) in the electrode up to 50% of the total electrode weight from the thickness direction to the electrode surface from the thickness direction to the thickness direction (V2 / V1) is 85% or more and less than 100% A membrane-electrode assembly.
[2] The above electrode is an ion conductive membrane with respect to the weight (W1) of the polymer electrolyte / catalyst particles in the electrode up to 50% of the total electrode weight in the thickness direction from the electrode surface to the ion conductive membrane side. The ratio (W2 / W1) of the weight ratio (W2 / W1) of the polymer electrolyte / catalyst particles in the electrode up to 50% of the total electrode weight from the side to the thickness direction is greater than 100% and not more than 130%. The membrane-electrode assembly according to [1], which is characterized.
[3] The membrane-electrode assembly according to [1] or [2], wherein at least one of the anode electrode and the cathode electrode is formed of a plurality of layers.
[4] The polymer electrolyte used in at least one of the ion conductive membrane, anode electrode and cathode electrode shares a polymer segment (A) having an ion conductive component and a polymer segment (B) having no ion conductive component. The membrane-electrode assembly according to any one of [1] to [3], wherein the membrane-electrode assembly is a bonded block copolymer.
[5] The main chain skeleton forming the polymer electrolyte used for at least one of the ion conductive membrane, the anode electrode, and the cathode electrode has a structure in which an aromatic ring is covalently bonded with a linking group [1] The membrane-electrode assembly of [4].
[6] The polymer electrolyte used for at least one of the ion conductive membrane, the anode electrode, and the cathode electrode is a sulfonic acid group-containing polyarylene having a structure represented by the following general formula (1): The membrane-electrode assembly according to 1] to [5].

[In the formula (1), Y represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, —
(CF ₂ ) _i — (i represents an integer of 1 to 10) or —C (CF ₃ ) ₂ —, Z is independently a direct bond, — (CH ₂ ) _j — (j is 1 to Represents an integer of 10.), —C (CH ₃ ) ₂ —, —O— or —S—, and Ar represents —SO ₃ H, —O (CH ₂ ) _p SO ₃ H or —O (CF _{2) p} SO ₃ H _(p represents an aromatic group having a substituent represented by indicating.) an integer of 1 to 12, m represents an integer of 0, n is an integer of 0 K represents an integer of 1 to 4.

A and D are each independently a direct bond, —CO—, —SO ₂ —, —SO—, —CON
H—, —COO—, — (CF ₂ ) _i — (i represents an integer of 1 to 10), — (CH ₂ ) _j — (j represents an integer of 1 to 10), —CR ′. _2- (R ′ represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group or a halogenated hydrocarbon group), a cyclohexylidene group, a fluorenylidene group, —O— or —S—, and B is independently An oxygen atom or a sulfur atom, and R ^{1 to} R ¹⁶
Each independently represents a hydrogen atom, a fluorine atom, an alkyl group, a halogenated alkyl group partially or wholly halogenated, an allyl group, an aryl group, a nitro group or a nitrile group, and s and t are each 0 to 4 represents an integer, and r represents 0 or an integer of 1 or more.

Z represents a direct bond or at least one structure selected from the group consisting of —O— and —S—, and Y represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO. -,-(CF ₂ ) _l
-(L is an integer of 1 to 10), at least one structure selected from the group consisting of -C (CF ₃ ) _2- , and R ²⁰ represents a nitrogen-containing heterocyclic group. q represents an integer of 1 to 5, and p represents an integer of 0 to 4. x, y, z represents a molar ratio when x + y + z = 100 mol%. ] [7] At least one of the anode electrode and the cathode electrode as a water repellent,
(A) a fluorine-containing copolymer having a structural unit derived from (meth) acrylate containing a polyfluoroalkyl group, and / or (B) represented by the following general formula (2) derived from a fluorine-containing olefin monomer. And a fluorine-containing copolymer having a structural unit represented by the following general formula (3) derived from a vinyl ether monomer:

[In Formula (2), X ¹ is a fluorine atom, a fluoroalkyl group or a group represented by —OW ¹ (W ¹
Represents an alkyl group or a fluoroalkyl group. ). ]

[In the formula (3), X ² represents a hydrogen atom or a methyl group, and X ³ represents a group represented by — (CH ₂ ) _h OW ² (W ² represents an alkyl group, a hydroxyalkyl group, a glycidyl group or a fluoroalkyl group. H represents an integer of 0 to 2), a group represented by -OCOW ³ (W ³ represents an alkyl group, a hydroxyalkyl group or a glycidyl group), a carboxyl group or an alkoxycarbonyl group. . ]
The membrane-electrode assembly according to any one of [1] to [6], comprising:
[8] At least one of the anode electrode and the cathode electrode is formed of a plurality of layers,
The electrode formed from a plurality of layers, wherein (V2 / V1) is 85% or more and less than 100% [1] to [7].
[9] A method for producing a membrane-electrode assembly in which an electrode paste containing a polymer electrolyte and catalyst particles is applied at least twice on an ion conductive membrane, the polymer in the electrode paste used for the first layer The ratio (P1 / P2) of the weight ratio (P1 / P2) of the polymer electrolyte / catalyst particles in the electrode paste used in the second layer or more to the weight ratio (P2) of the electrolyte / catalyst particles is 110% or more, 400 % Or less, a method for producing a membrane-electrode assembly.

  The membrane-electrode assembly of the present invention has a power generation performance and power generation even in a high temperature region by bringing the pore volume in the thickness direction in the electrode and the distribution state of the polymer electrolyte closer to be uniform in the thickness direction. Durability can be further improved. Therefore, if the membrane-electrode assembly of the present invention is used, a fuel cell exhibiting excellent power generation characteristics can be obtained.

Hereinafter, the present invention will be described in more detail.
[I. Membrane-electrode assembly]
(1) Configuration of Membrane-Electrode Assembly The membrane-electrode assembly of the present invention comprises an ion conductive membrane, and an anode electrode and a cathode electrode that are provided on both sides of the ion conductive membrane and each include catalyst particles and a polymer electrolyte. In this membrane-electrode assembly, the pore volume in the thickness direction is uniform in at least one of the anode electrode and the cathode electrode. These electrodes serve as an electrochemical reaction field, and an electrode base material that promotes gas diffusion and collects current is usually bonded to the surface.

Specifically, as shown in FIG. 1, in at least one of the anode electrode and the cathode electrode, the total electrode weight is measured in the thickness direction from the electrode surface (bonding surface with the electrode base material) to the ion conductive membrane side. The pore volume (V2) in the electrode up to 50% of the total electrode weight in the thickness direction from the ion conductive membrane side to the electrode surface with respect to the pore volume (V1) in the electrode up to 50%. Ratio (V2 / V1) is 8
It is characterized by being 5% or more and less than 100%.

More preferably, the ratio (V2 / V1) is 90% to 99%. Within the above ratio,
Insufficiency of gas diffusivity, drainage, proton conductivity, and electron conductivity due to local distribution of pore volume in the thickness direction of the electrode is eliminated, and the reaction proceeds efficiently throughout the thickness direction of the electrode. Sufficient power generation performance and power generation durability can be obtained.

The pore volume of the electrode can be measured by mercury porosimetry. Both the pore volume (V1) and the pore volume (V2) are preferably in the range of 0.05 to 2.0 ml / g- (electrode).
If the pore volume exceeds the above range and is too large, the mechanical properties tend to deteriorate. In addition, the electron conduction and proton conduction paths are cut, and the power generation performance may be reduced. On the other hand, if it is less than the above range, gas diffusibility and water discharge properties are poor, and power generation performance may be reduced. The pore volume in the electrode depends on the electrode paste preparation conditions described later, specifically, the stirring method, in the case of bead stirring, the bead diameter and the amount of beads, the stirring time, the amount of polymer electrolyte, the amount of carbon fiber, etc. ,Change. In general, the larger the amount of the polymer electrolyte, the smaller the pore volume, while the smaller the amount, the larger the pore volume.

  V1 is preferably in the range of 0.08 to 2.0 ml / g- (electrode), and more preferably in the range of 0.15 to 1.5 ml / g- (electrode). V2 is preferably in the range of 0.07 to 1.8 ml / g- (electrode), and more preferably in the range of 0.10 to 1.3 ml / g- (electrode). If it exists in this range, moisture resistance can be made high.

  In order to measure V2, in the thickness direction from the ion conductive membrane side to the electrode surface, electrodes up to 50% of the total electrode weight are connected from the electrode surface (joint surface with the electrode substrate) to the ion conductive membrane side. It is produced by uniformly shaving up to 50% of the total electrode weight in the thickness direction. After measuring the pore volume (V2) of this electrode by the mercury intrusion method, V1 can be obtained by subtracting V2 from the pore volume of all electrodes.

In the present invention, it is sufficient that either the anode electrode or the cathode electrode satisfies the above pore volume, and it is preferable that the cathode electrode is satisfied.
Further, it is preferable that the weight ratio of the polymer electrolyte / catalyst particles is uniformly distributed in the thickness direction in at least one of the anode electrode and the cathode electrode. Specifically, the weight ratio of polymer electrolyte / catalyst particles in the electrode up to 50% of the total electrode weight in the thickness direction from the electrode surface (bonding surface with the electrode base material) to the ion conductive membrane side (W1 ) In the thickness direction from the ion conductive membrane side to the electrode surface, the weight ratio of polymer electrolyte / catalyst particles in the electrode up to 50% of the total electrode weight (W2
) Ratio (W2 / W1) is preferably greater than 100% and 130% or less. More preferably, the ratio is 101 to 120%. With the above ratio, the lack of compatibility of gas diffusivity, drainage, proton conductivity, and electron conductivity due to the local distribution of the polymer electrolyte in the thickness direction of the electrode is resolved, and efficiency is achieved throughout the thickness direction of the electrode. Since the reaction proceeds well, sufficient power generation performance and power generation durability can be obtained. Moreover, since the polymer electrolyte is present within the above range in the thickness direction of the electrode, the pore volume per unit area of the above electrode can be adjusted within the above range.

W1 is preferably in a ratio of 0.05 to 1.9, and more preferably in a ratio of 0.1 to 1.5. W2 is preferably in a ratio of 0.1 to 2.3, and more preferably in a ratio of 0.2 to 1.9. If it exists in this range, ion conductivity can fully be ensured and moisture resistance can be made high.

When measuring W1 and W2, in the thickness direction from the electrode surface to the ion conductive membrane side, the electrode up to 50% of the total electrode weight is uniformly scraped in the plane direction with a scalpel, and the scraped one is collected. The collected sample is an electrode up to 50% of the total electrode weight in the thickness direction from the electrode surface to the ion conductive membrane side. Further, in the thickness direction from the ion conductive membrane side to the electrode surface, the electrode up to 50% of the total electrode weight is up to 50% of the total electrode weight in the thickness direction from the electrode surface to the ion conductive membrane side. After scraping off the electrode, in the same way, scrape the ion conductive film toward the ion conductive film side to the limit where the ion conductive film is not contaminated, collect the scraped material, and measure the thickness direction from the ion conductive film side to the electrode surface. Furthermore, the electrode is up to 50% of the total electrode weight. These electrodes were measured with a fluorescent X-ray apparatus, and the strength of atoms unique to the polymer electrolyte (for example, sulfur atoms derived from sulfonic acid) and atoms derived from the catalyst particles (for example, platinum atoms) in the electrodes was determined. Calculate the intensity ratio of atoms unique to molecular electrolyte / atoms derived from catalyst particles. Using the strength ratio of each electrode, the weight ratio (W1) of the polymer electrolyte / catalyst particles in the electrode up to 50% of the total electrode weight in the thickness direction from the electrode surface to the ion conductive membrane side, and The weight ratio (W2) of the polymer electrolyte / catalyst particles in the electrode up to 50% of the total electrode weight is determined in the thickness direction from the ion conductive membrane side to the electrode surface, and the ratio (W2 / W1) is calculated.

At least one of the anode electrode and the cathode electrode may be formed of a plurality of layers.
Specifically, it is preferable that the layer is composed of a plurality of layers in which V1 and W1 are in a specific range and V2 and W2 are in a specific range, and V2 / V1 and W2 / W1 have the above-described ratio. .
(2) Manufacturing Method of Membrane-Electrode Assembly As one specific manufacturing method of the membrane-electrode assembly according to the present invention, for example, an electrode paste is applied on an ion conductive film and dried to form an electrode 1 The electrode 2 can be formed by applying an electrode paste having a larger weight ratio to the weight ratio of the catalyst particles / polymer electrolyte in the electrode 1 and drying the electrode paste. . After obtaining the electrodes laminated in this way, the gas diffusion layer can be pressure-bonded by hot pressing.

  Further, for example, after applying an electrode paste on carbon paper (gas diffusion layer) subjected to water repellent treatment to form the electrode 3, the weight of the polymer electrolyte relative to the weight of the catalyst particles of the electrode 3 is further formed thereon. Alternatively, a method may be used in which an electrode 4 having a large weight ratio is applied and dried to form the electrode 4. After obtaining the electrode laminated in this way, the electrode can be formed on the ion conductive film by hot pressing on the ion conductive film.

  Further, for example, a certain electrode paste is applied onto a polytetrafluoroethylene film as a transfer substrate and dried to form the electrode 5, and the ratio of the weight of the polymer electrolyte to the weight of the catalyst particles of the electrode 5 is further formed thereon. In contrast, an electrode paste having a large weight ratio may be applied and dried to form the electrode 6 and then hot-pressed and transferred to the ion exchange membrane.

The method for producing a membrane-electrode assembly according to the present invention is preferably a method for producing a membrane-electrode assembly in which an electrode paste containing a polymer electrolyte and catalyst particles is applied at least twice on an ion conductive membrane. The weight ratio of the polymer electrolyte / catalyst particles in the electrode paste used in the second layer or more (P1) to the weight ratio of the polymer electrolyte / catalyst particles in the electrode paste used in the first layer (P1) ) Ratio (P1 / P2) is 110% or more and 400% or less. Preferably, it is 120% or more and 300% or less. By having such a configuration, the polymer electrolyte /
Not only can the ratio (W1 / W2) of the weight ratio of catalyst particles (W2 and W1) fall within the above-mentioned range, but also the pore volume in the thickness direction of the electrode and the weight ratio of the polymer electrolyte / catalyst particles. The distribution can be greatly homogenized as compared with the case of applying the electrode paste only once.

Although the reason for this is not clear, when an electrode is formed with only one layer with one type of paste, the electrode has different wettability to the coated substrate of the catalyst particles and the polymer electrolyte, and the specific gravity of each electrode. We believe that there is a distribution in pore volume and weight ratio of polymer electrolyte / catalyst particles in the thickness direction. For this reason, it is considered that by using two or more kinds of pastes having different concentrations, this problem can be solved and an electrode having a uniform pore volume and weight ratio can be formed. In particular, when the electrode paste is applied only once to the ion exchange membrane, the membrane electrolyte polymer / catalyst particle ratio tends to increase with respect to the electrode surface. It is considered that the polymer electrolyte / catalyst particle ratio applied to the (first layer) can be made relatively uniform throughout the electrode by making the polymer electrolyte / catalyst particle ratio smaller than the electrode surface side (second layer). It is done.

When catalyst-supported carbon is used as the catalyst particles in the electrode paste, the weight ratio of (polymer electrolyte / carbon in the catalyst particles) in the electrode paste first applied to the coated substrate side is 0.1. To 2.0, more preferably 0.2 to 1.6, and the weight ratio of the electrode paste (polymer electrolyte / carbon in the catalyst particles) applied after the second time is 0.3 to 2.5. More preferably, it is 0.4-2.0.

If the weight ratio of the polymer electrolyte / catalyst particles in the electrode paste applied in the first and second and subsequent times is within the above range, the pore volume in the thickness direction of the electrode and the polymer The distribution of the electrolyte can be controlled to a relatively homogeneous distribution state, and sufficient power generation performance and power generation durability can be obtained.

  The lamination of the electrode paste having the weight ratio of the polymer electrolyte to the different catalyst particles may be repeated any number of times, but usually 2 to 5 times, preferably 2 to 4 times, more preferably 2 to 3 times. It is.

  The pore volume in the electrode depends on the preparation conditions of the electrode paste, and depending on the stirring method (equipment), in the case of bead stirring, the bead diameter and the amount of beads, the stirring time, the amount of polymer electrolyte, the amount of carbon fiber, etc. Change. In general, the larger the amount of the polymer electrolyte, the smaller the pore volume, while the smaller the amount, the larger the pore volume.

Application methods The paste application methods include brush coating, brush coating, bar coater coating, knife coater coating, doctor blade method, screen printing, spray coating, etc., which can be applied to other substrates (transfer substrates). After forming the electrode once, it may be transferred to the electrode substrate or the ion conductive film. As the transfer substrate in this case, a polytetrafluoroethylene (PTFE) sheet or a glass plate or a metal plate whose surface is treated with a release agent can be used.

  As an electrode base material, the electrode base material generally used for a fuel cell is used without particular limitation. For example, a porous conductive sheet having a conductive material as a main constituent material can be mentioned. Examples of the conductive material include a fired body from polyacrylonitrile, a fired body from pitch, a carbon material such as graphite and expanded graphite, stainless steel, and the like. Examples include steel, molybdenum, and titanium. The form of the conductive material is not particularly limited, such as fibrous or particulate, but a fibrous conductive inorganic substance (inorganic conductive fiber), particularly carbon fiber is preferable. As a porous conductive sheet using inorganic conductive fibers, either a woven fabric or a non-woven fabric structure can be used. As the woven fabric, plain weaving, oblique weaving, satin weaving, crest weaving, binding weaving and the like are not particularly limited. Moreover, as a nonwoven fabric, what was manufactured by methods, such as a papermaking method, a needle punch method, a spun bond method, a water jet punch method, a melt blow method, is used, without being specifically limited. The porous conductive sheet using inorganic conductive fibers may be a knitted fabric.

  In particular, when carbon fibers are used as these fabrics, a woven fabric obtained by carbonizing or graphitizing a plain woven fabric using flame-resistant spun yarn, and a flame-resistant yarn is carbonized after being processed into a nonwoven fabric by a needle punch method or a water jet punch method. A graphitized non-woven fabric, a mat non-woven fabric by a paper making method using a flame-resistant yarn, a carbonized yarn or a graphitized yarn is preferable. For example, Toray carbon paper TGP series, SO series, E-TEK carbon cloth, etc. are preferably used.

  It is also a preferred embodiment that conductive particles such as carbon black or conductive fibers such as carbon fibers are added to the porous conductive sheet as an auxiliary agent in order to improve conductivity. These also correspond to the diffusion layer.

The thickness of the applied coating film (that is, the thickness of the catalyst electrode) is not particularly limited, but the metal supported as a catalyst is 0.05 to 4.0 mg / cm per unit surface area of the coating. ² , preferably in the range of 0.1 to 2.0 mg / cm ² .

Within this range, sufficiently high catalytic activity is exhibited, and protons can be extracted efficiently. Supported metal as a catalyst for the electrode when the non recoating the electrode unit surface area per coating, 0.05~3.0mg / cm ^2, the range preferably of 0.1 to 2.0 mg / cm ² It is desirable to be in If it is less than the above range, the effect of overcoating is small. On the other hand, if it exceeds the above range, the electrode becomes thick and cracks may occur, resulting in insufficient mechanical strength.

The conditions of the hot press are as follows: the temperature is 30 ° C. to 200 ° C., preferably 40 ° C. to 180 ° C., the pressure is 5 to 300 kg / cm ² , preferably 10 to 180 kg / cm ² , and the time is 30 seconds to 60 minutes, preferably 1 to 30 minutes. By performing hot pressing under conditions within the above range, the bondability between the electrode layer and the film is improved.

Moreover, when joining gas diffusion layers, such as carbon paper, on the said electrode, an electrode and a gas diffusion layer can be joined by the hot press conditions similar to the above.
(3) Diffusion layer A gas diffusion layer may be provided on the electrode surface as required.

Examples of the diffusion layer include water-repellent treated porous conductive sheets such as carbon paper, and the diffusion layer includes conductive particles such as carbon black and carbon fibers as an auxiliary agent for improving conductivity. Fibers may be added. Note that the diffusion layer is not necessarily provided because the electrode substrate also has the function.
[II. electrode]
(1) Structure of electrode The electrode of the present invention is manufactured by applying an electrode paste to an ion conductive film and drying as a rule, as described in the method for manufacturing a membrane-electrode assembly. Hereinafter, the electrode paste will be described in detail.
(2) Electrode paste The electrode paste used in the present invention is prepared, for example, by dispersing catalyst particles, a polymer electrolyte and, if necessary, a water repellent in an organic solvent, and kneading by a conventionally known method. Is done.

  Although the mixing order of each component is not specifically limited, for example, all components are mixed and stirred for a certain period of time, or components other than the dispersant are mixed and stirred for a certain period of time, and then a dispersant is added as necessary. It is preferable to add and to stir for a certain time. Moreover, you may adjust the quantity of an organic solvent and water as needed, and may adjust the viscosity of a composition.

Below, the component contained in an electrode paste is demonstrated.
(I) Catalyst Particles The catalyst particles consist of a catalyst supported on carbon or a metal oxide carrier, or a single catalyst.

Platinum or a platinum alloy is used as the catalyst. When a platinum alloy is used, stability and activity as an electrode catalyst can be further imparted. Such platinum alloys include platinum group metals other than platinum (ruthenium, rhodium, palladium, osmium, iridium), iron, cobalt, titanium, gold, silver, chromium, manganese, molybdenum, tungsten, aluminum, silicon, rhenium. An alloy of platinum and one or more selected from zinc and tin is preferable, and the platinum alloy may contain an intermetallic compound of a metal alloyed with platinum.

The catalyst forms catalyst particles both in a simple substance and in a state where it is supported on a carrier.
As the carrier for supporting the catalyst, carbon black such as oil furnace black, channel black, lamp black, thermal black and acetylene black is preferably used in view of the electron conductivity and the specific surface area. Further, artificial graphite or carbon obtained from organic compounds such as natural graphite, pitch, coke, polyacrylonitrile, phenol resin, furan resin, and the like may be used.

  Examples of the oil furnace black include “Vulcan XC-72”, “Vulcan P”, “Black Pearls 880”, “Black Pearls 1100”, “Black Pearls 1300”, “Black Pearls 2000”, and “Regal 400” manufactured by Cabot Corporation. “Ketjen Black EC” manufactured by Lion Corporation, “# 3150, # 3250” manufactured by Mitsubishi Chemical Corporation, and the like. Examples of the acetylene black include “DENKA BLACK” manufactured by Denki Kagaku Kogyo.

  As the form of these carbons, in addition to particles, fibers can also be used. Further, the amount of the catalyst supported on the carbon is not particularly limited as long as the catalyst activity can be effectively exhibited, but the supported amount is 0.1 to 9.0 g- with respect to the carbon weight. Metal / g-carbon, preferably in the range of 0.25 to 2.4 g-metal / g-carbon.

In addition to carbon, the carrier may be a metal oxide such as titania, zinc oxide, silica, ceria, alumina, alumina spinel, magnesia, zirconia, and the like.
(Ii) Polymer electrolyte The polymer electrolyte serves as a binder component that binds the carbon carrying the catalyst, and on the anode side, it efficiently supplies ions generated by the reaction on the catalyst to the ion conductive membrane. On the cathode side, the ions supplied from the ion conductive membrane are efficiently supplied to the catalyst.

  The polymer electrolyte used in the present invention is not particularly limited, but a polymer segment (A) having an ion conductive component composed of a sulfonic acid group or a phosphate group and a polymer segment (B) having no ion conductive component are covalently bonded. The block copolymer is preferred. More preferably, the main chain skeleton forming the copolymer is a polyarylene having a structure in which an aromatic ring is covalently bonded with a linking group, and particularly preferably a structural unit represented by the following general formula (A): And a polyarylene having a sulfonic acid group represented by the following general formula (C) including a structural unit represented by the following general formula (B). When such polyarylene is used, an electrode having higher heat resistance and higher mechanical strength can be formed.

First, the polyarylene having a sulfonic acid group used in the present invention will be specifically described.
As the sulfonic acid group-containing polyarylene, preferably, a polymer segment (A) having a sulfonic acid group, a polymer segment (B) not having an ion conductive component, and a segment having a nitrogen-containing heterocyclic group (C) ) Are covalently bonded block copolymers, and particularly preferably a structural unit represented by the following general formula (A) (hereinafter also referred to as “structural unit (A)” or “sulfonic acid unit”). And a structural unit represented by the following general formula (B) (hereinafter also referred to as “structural unit (B)” or “hydrophobic unit”), and a structural unit represented by the following general formula (C) (hereinafter referred to as “structural unit (B)”). , Which is also referred to as “structural unit (C)” or “basic unit”), and a polyarylene having a sulfonic acid group represented by the following general formula (D).
Structural unit (A) (sulfonic acid unit)

In the above formula (A), Y represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO—.
_{, - (CF 2) i -} (i is an integer from 1 to 10.) Or -C (CF _{3) 2} - shows a. Of these, —CO— and —SO ₂ — are preferable.

Z independently represents a direct bond, — (CH ₂ ) _j — (j represents an integer of 1 to 10), —C (CH ₃ ) ₂ —, —O— or —S—. Among these, a direct bond and —O— are preferable.

Ar is —SO ₃ H, —O (CH ₂ ) _p SO ₃ H or —O (CF ₂ ) _p SO ₃ H (p is 1 to
An integer of 12 is shown. The aromatic group which has a substituent represented by this is shown. Examples of the aromatic group include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and the like. In these, a phenyl group and a naphthyl group are preferable. Ar represents —SO ₃ H;
It is necessary to have at least one substituent represented by —O (CH ₂ ) _p SO ₃ H or —O (CF ₂ ) _p SO ₃ H, and two in the case of a naphthyl group It is preferable to have the above.

m is an integer of 0 to 10, preferably 0 to 2, n is an integer of 0 to 10, preferably 0 to 2, and k is an integer of 1 to 4.
As a preferred structure of the structural unit (A), in the above formula (A),
(1) a structure in which m = 0, n = 0, Y is —CO—, and Ar is a phenyl group having —SO ₃ H as a substituent;
(2) a structure in which m = 1, n = 0, Y is —CO—, Z is —O—, and Ar is a phenyl group having —SO ₃ H as a substituent;
(3) A structure in which m = 1, n = 1, k = 1, Y is —CO—, Z is —O—, and Ar is a phenyl group having —SO ₃ H as a substituent;
(4) a structure in which m = 1, n = 0, Y is —CO—, Z is —O—, and Ar is a naphthyl group having two —SO ₃ H as substituents;
(5) m = 1, n = 0, Y is —CO—, Z is —O—, and Ar is a phenyl group having —O (CH ₂ ) ₄ SO ₃ H as a substituent. Examples include structures.
Structural unit (B) (hydrophobic unit)

In the above formula (B), A and D are each independently a direct bond, —CO—, —SO ₂ —, —
SO—, —CONH—, —COO—, — (CF ₂ ) _i — (i represents an integer of 1 to 10), — (CH ₂ ) _j — (j represents an integer of 1 to 10) , -CR _'2 -, cyclohexylidene group,
A fluorenylidene group, -O- or -S- is shown. Among these, a direct bond, —CO—, —SO ₂ —, —CR ′ ₂ —, a cyclohexylidene group, a fluorenylidene group, and —O— are preferable. R ′ represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group or a halogenated hydrocarbon group. For example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, A propyl group, an octyl group, a decyl group, an octadecyl group, a phenyl group, a trifluoromethyl group, etc. are mentioned.

B independently represents an oxygen atom or a sulfur atom, preferably an oxygen atom.
R ^{1 to} R ¹⁶ each independently represent a hydrogen atom, a fluorine atom, an alkyl group, a halogenated alkyl group, an allyl group, an aryl group, a nitro group or a nitrile group, which is partially or wholly halogenated.

Examples of the alkyl group in R ^{1 to} R ¹⁶ include a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group, a hexyl group, a cyclohexyl group, and an octyl group. Examples of the halogenated alkyl group include a trifluoromethyl group, a pentafluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group. Examples of the allyl group include a propenyl group. Examples of the aryl group include a phenyl group and a pentafluorophenyl group.

s and t each represent an integer of 0 to 4. r shows 0 or an integer greater than or equal to 1, and an upper limit is 100 normally, Preferably it is 1-80.
As a preferred structure of the structural unit (B), in the above formula (B),
(1) s = 1, t = 1, A is —CR ′ ₂ —, a cyclohexylidene group or a fluorenylidene group, B is an oxygen atom, and D is —CO— or —SO ₂ —. , R ^{1 to} R ¹⁶ are hydrogen atoms or fluorine atoms,
(2) A structure in which s = 1, t = 0, B is an oxygen atom, D is —CO— or —SO ₂ —, and R ^{1 to} R ¹⁶ are hydrogen atoms or fluorine atoms,
(3) s = 0, t = 1, A is —CR ′ ₂ —, a cyclohexylidene group or a fluorenylidene group, B is an oxygen atom, and R ^{1 to} R ¹⁶ are a hydrogen atom, a fluorine atom or Examples thereof include a structure that is a nitrile group.
Structural unit (C) (basic unit)

In the formula, Z represents a direct bond or at least one structure selected from the group consisting of —O— and —S—, and Y represents —CO—, —SO ₂ —, —SO—, —CONH—. _{, -COO -, - (CF 2} ) l - (l is an integer of 1 to _{10), - C (CF 3)} 2 - represents at least one structure selected from the group consisting of, R ²⁰ is A nitrogen-containing heterocyclic group is shown. q represents an integer of 1 to 5, and p represents an integer of 0 to 4.

The nitrogen-containing heterocyclic group is not particularly limited, but pyrrole, thiazole, isothiazole, oxazole, isoxazole, pyridine, imidazole, imidazoline, pyrazole, 1,3,5-triazine, pyrimidine, pyritazine, pyrazine, Derived from a compound selected from the group consisting of nitrogen-containing heterocyclic compounds consisting of indole, quinoline, isoquinoline, bryne, benzimidazole, benzoxazole, benzthiazole, tetrazole, tetrazine, triazole, carbazole, acridine, quinoxaline, quinazoline and their derivatives Or at least one kind of group which may be used in combination.
(Polymer electrolyte structure)

In the above formula (D), A, B, D, Y, Z, Ar, k, m, n, r, s, t and R ^{1 to} R ¹⁶ are represented by the above formulas (A), (B) and (C ) And x, y, and z represent molar ratios when x + y + z = 100 mol%.

  The structural units (B) and (C) are optional components, and the remainder excluding (A) in the polymer corresponds to the amount of the structural units (B) and (C). Moreover, (B) and (C) may not be included. When this structural unit (B) is included, it is easy to adjust the molecular weight, the content of each repeating unit, the ion exchange amount, and the like, while suppressing swelling and elution in hot water, , A thermally and chemically stable polymer can be obtained. By including the structural unit (C), the stability of the sulfonic acid group under high temperature conditions is improved by the action of the nitrogen-containing heterocyclic group, and as a result, the heat resistance is improved. Since the nitrogen atom of the nitrogen-containing heterocyclic aromatic compound has basicity, it forms an ionic interaction with the sulfonic acid group. This enhances the stability of the sulfonic acid group and suppresses the elimination of the sulfonic acid group under high temperature conditions. Similarly, the cross-linking reaction between polymer molecules derived from sulfonic acid groups can be suppressed under high temperature conditions. The nitrogen-containing heterocyclic aromatic compound is a compound having an adequately strong basicity that can exhibit these effects without impairing proton conductivity.

  The above-mentioned ion exchange capacity can be adjusted by changing the type, usage ratio, and combination of the structural unit (A), the structural unit (B), and the structural unit (C). Therefore, the ion exchange capacity can be adjusted by changing the charge amount ratio and type of the precursor (monomer / oligomer) that induces the structural units (A) to (C) during the polymerization. If the ion exchange capacity of the polymer electrolyte having a fluorine content of 0 to 40% is too low, the proton conductivity in the fuel cell cannot be expressed and sufficient output cannot be obtained. On the other hand, if it is too high, the hot water generated in the fuel cell will clog the pores due to dissolution and swelling, thereby preventing the reactive gas from reaching the catalyst and reducing the power generation output. Preferably, it is 0.5 to 3.0 meq / g, more preferably 0.8 to 2.8 meq / g.

Further, the repeating structural unit represented by the formula (C) with respect to the repeating structural unit represented by the formula (A) (that is, the unit of x), that is, the unit of [] _x ,
] Ratio of the proportion of units of _{z (z} / x) is 0.001 mol% to 50 mol%, preferably from 0.1 mol% to 30 mol%, more preferably, 1 mol% 25 mol%.

The molecular weight of the polymer is 10,000 to 1,000,000, preferably 20,000 to 800,000 in terms of polystyrene-equivalent weight average molecular weight by gel permeation chromatography (GPC).
<Method for producing sulfonated polyarylene>
For the production of a polymer having a sulfonic acid group constituting the polymer electrolyte (sulfonated polyarylene), for example, the following three methods A, B and C can be used.

(Method A)
For example, similarly to the method described in JP-A-2004-137444, a monomer represented by the following general formula (A ′), a monomer represented by the following general formula (B ′), and the following general formula (C ′) To produce a polymer having a sulfonic acid ester group, deesterifying the sulfonic acid ester group, and converting the sulfonic acid ester group into a sulfonic acid group. it can.
Monomer (A ')

X represents an atom or group selected from a chlorine atom, a bromine atom and —OSO ₂ Rb (wherein Rb represents an alkyl group, a fluorine-substituted alkyl group or an aryl group).
Y, Z, Ar, m, n, and k are the same as those in formula (A), and R represents an alkyl group having 4 to 12 carbon atoms.

  Specific examples of the compound represented by the general formula (A ′) include a compound represented by the following general formula, JP-A Nos. 2004-137444, 2004-345997, and 2004-346163. Mention may be made of the sulfonic acid esters described in the publication.

In the compound represented by the general formula (A ′), the sulfonate structure is usually bonded to the meta position of the aromatic ring.
Monomer (B ')
The monomer (B ′) is represented by the following formula (B ′).

R ′ and R ″ represent an atom or group selected from a chlorine atom, a bromine atom and —OSO ₂ Rb (where Rb represents an alkyl group, a fluorine-substituted alkyl group or an aryl group).
R ^{1 to} R ¹⁶ , A, B, D, s, t, and r are the same as those in the general formula (B).

As specific examples of the monomer (B ′), when r in the general formula (B ′) is 0, for example, 4,4′-dichlorobenzophenone, 4,4′-dichlorobenzanilide, 2,2-bis (4-
Chlorophenyl) difluoromethane, 2,2-bis (4-chlorophenyl) -1,1,1,3,3,3-hexafluoropropane, 4-chlorobenzoic acid-4-chlorophenyl ester, bis (4-chlorophenyl) sulfoxide , Bis (4-chlorophenyl) sulfone, and 2,6-dichlorobenzonitrile. In these compounds, a compound in which a chlorine atom is replaced with a bromine atom or an iodine atom is exemplified.

When r in the general formula (B ′) is 1, the compounds listed below and JP-A-2003
And the compounds described in JP-A-113136.

  When r in the general formula (B ′) is r ≧ 2, for example, compounds having the following structures can be given.

Monomer (C ')
The monomer (C ′) is represented by the following formula (C ′).

X represents an atom or group selected from a chlorine atom or a bromine atom, and -OSO ₂ Rb (wherein Rb represents an alkyl group, a fluorine-substituted alkyl group or an aryl group).
Y, Z, R ²⁰ , p and q are the same as in the general formula (C).

  Specific examples of the monomer (C) include the following compounds.

Furthermore, compounds in which a chlorine atom is replaced with a bromine atom, and isomers having different bonding positions of chlorine and bromine atoms can be exemplified. In addition, a compound in which a —CO— bond is replaced with a —SO ₂ — bond can be exemplified. These compounds may be used alone or in combination of two or more.

  Examples of the method for synthesizing the monomer (C ′) include a method in which a compound represented by the following general formula (4) and a nitrogen-containing heterocyclic compound are subjected to a nucleophilic substitution reaction.

  In the formula, X, Y, p and q are the same as those defined in the general formula (C ′). X 'represents a halogen atom. A fluorine atom or a chlorine atom is preferable, and a fluorine atom is more preferable.

  Specific examples of the compound represented by the general formula (4) include 2,4-dichloro-4′-fluorobenzophenone, 2,5-dichloro-4′-fluorobenzophenone, and 2,6-dichloro-4′-fluoro. Benzophenone, 2,4-dichloro-2'-fluorobenzophenone, 2,5-dichloro-2'-fluorobenzophenone, 2,6-dichloro-2'-fluorobenzophenone, 2,4-dichlorophenyl-4'-fluorophenylsulfone 2,5-dichlorophenyl-4'-fluorophenylsulfone, 2,6-dichlorophenyl-4'-fluorophenylsulfone, 2,4-dichlorophenyl-2'-fluorophenylsulfone, 2,4-dichlorophenyl-2'-fluoro Phenylsulfone, 2,4-dichlorophenyl-2'-fluoroph Vinyl sulfonic. Of these compounds, 2,5-dichloro-4'-fluorobenzophenone is preferred.

The nitrogen-containing heterocyclic compound has active hydrogen, and this active hydrogen is subjected to a substitution reaction with the group represented by X ′ of the compound represented by the general formula (4).
Examples of the nitrogen-containing heterocyclic compound having active hydrogen include pyrrole, thiazole, isothiazole, oxazole, isoxazole, pyridine, imidazole, imidazoline, pyrazole, 1,3,5-triazine, pyrimidine, pyritazine, pyrazine, indole, quinoline, Isoquinoline, bromine, benzimidazole, benzoxazole, benzthiazole, tetrazole, tetrazine, triazole, carbazole, acridine, quinoxaline, quinazoline, 2-hydroxypyridine, 3-hydroxypyridine, 4-hydroxypyridine, 3-hydroxyquinoline, 8-hydroxy Quinoline, 2-hydroxypyrimidine, 2-mercaptopyridine, 3-mercaptopyridine, 4-mercaptopyridine, 2-mercaptopyrimidine, 2-me , And the like mercapto benzthiazole.

Of these compounds, pyrrole, imidazole, indole, carbazole, benzoxazole, and benzimidazole are preferable.
The reaction between the compound represented by the general formula (4) and the nitrogen-containing heterocyclic compound having active hydrogen is preferably performed in an organic solvent. A polar solvent such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, sulfolane, diphenylsulfone, dimethylsulfoxide is used. In order to accelerate the reaction, alkali metal, alkali metal hydride, alkali metal hydroxide, alkali metal carbonate, or the like is used. The ratio of the compound represented by the general formula (2) to the nitrogen-containing heterocyclic compound having active hydrogen is such that the nitrogen-containing heterocyclic compound having equimolar or active hydrogen is added in excess. Specifically, the nitrogen-containing heterocyclic compound having active hydrogen is preferably used in an amount of 1 to 3 times mol, particularly 1 to 1.5 times mol of the compound represented by the general formula (4).

The reaction temperature is 0 ° C to 300 ° C, preferably 10 ° C to 200 ° C. The reaction time is 15 minutes to 100 hours, preferably 1 hour to 24 hours.
The product is preferably used after being purified by a method such as recrystallization.

Polymerization of the sulfonated polyarylene In order to obtain the polymer, the monomer (A ′), the monomer (C ′) and, if necessary, the monomer (B ′) are first copolymerized to obtain a precursor.

This copolymerization is carried out in the presence of a catalyst. The catalyst used at this time is a catalyst system containing a transition metal compound, and this catalyst system is (1) a transition metal salt and a ligand. Compound(
Hereinafter, it is referred to as “ligand component”. ), Or transition metal complexes with ligands coordinated (including copper salts)
As well as (2) a reducing agent as an essential component, and in order to further increase the polymerization rate, a “salt” may be added.

As specific examples of these catalyst components, the use ratio of each component, reaction solvent, concentration, temperature, time, and other polymerization conditions, the compounds and conditions described in JP-A No. 2001-342241 can be employed.

For example, as the transition metal salt, nickel chloride, nickel bromide and the like are preferably used, and as the compound serving as a ligand, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, Tri-p-tolylphosphine, tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, 2,2'-bipyridine and the like are preferably used. Furthermore, nickel chloride bis (triphenylphosphine) and nickel chloride (2,2′bipyridine) are preferably used as the transition metal (salt) in which the ligand is coordinated in advance. Examples of the reducing agent include iron, zinc, manganese, aluminum, magnesium, sodium, and calcium, and zinc, magnesium, and manganese are preferable. As the “salt”, sodium bromide, sodium iodide, potassium bromide, tetraethylammonium bromide, and tetraethylammonium iodide are preferable. A polymerization solvent may be used for the reaction, and specifically, tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide, 1-methyl-2-pyrrolidone and the like are preferably used.

  The proportion of each component used in the catalyst system is usually from 0.0001 to 10 mol, preferably from 0.0001 to 10 mol, based on 1 mol of the total amount of monomers of the transition metal salt or the transition metal (salt) coordinated with the ligand. 01-0.5 mol. If it exists in this range, it can polymerize with high catalyst activity and high molecular weight. When “salt” is used in the catalyst system, the amount used is generally 0.001 to 100 mol, preferably 0.01 to 1 mol, per 1 mol of the total amount of monomers. Within such a range, the effect of increasing the polymerization rate is sufficient. The total concentration of monomers in the polymerization solvent is usually 1 to 90% by weight, preferably 5 to 40% by weight. Moreover, the polymerization temperature at the time of superposing | polymerizing a polymer is 0-200 degreeC normally, Preferably it is 50-100 degreeC. The polymerization time is usually 0.5 to 100 hours, preferably 1 to 40 hours.

Next, the obtained polymer is hydrolyzed to convert the sulfonic acid ester group (—SO ₃ R) in the structural unit into a sulfonic acid group (—SO ₃ H).
Hydrolysis includes (1) a method in which the polymer having a sulfonic acid ester group is added to an excess amount of water or alcohol containing a small amount of hydrochloric acid, and the mixture is stirred for 5 minutes or longer. A method in which a polymer having an acid ester group is reacted at a temperature of about 80 to 120 ° C. for about 5 to 10 hours, (3) 1 to 3 mol per mol of the sulfonic acid ester group (—SO ₃ R) in the polymer After the polymer having a sulfonic acid ester group is reacted at a temperature of about 80 to 150 ° C. for about 3 to 10 hours in a solution containing double moles of lithium bromide, such as N-methylpyrrolidone, hydrochloric acid is added. It can be performed by the method of doing.

(Method B)
For example, as in the method described in JP-A No. 2001-342241, a monomer having a skeleton represented by the general formula (A ′) and having no sulfonic acid group or sulfonic acid ester group, and the monomer (B ′) and the monomer (C ′) can be copolymerized, and the polymer can be synthesized by sulfonation using a sulfonating agent.

  As specific examples of the monomer having no sulfonic acid group or sulfonic acid ester group that can be a structural unit represented by the above general formula (A) that can be used in Method B, JP-A-2001-342241, Mention may be made of the dihalides described in JP-A-2002-29389.

(Method C)
In the general formula (A), when Ar is an aromatic group having a substituent represented by —O (CH ₂ ) _h SO ₃ H or —O (CF ₂ ) _h SO ₃ H, for example, Similarly to the method described in Japanese Patent Application Laid-Open No. 2005-606254, a precursor monomer that can be a structural unit represented by the general formula (A), and a monomer that can be a structural unit represented by the general formula (B), Alternatively, it can be synthesized by a method in which an oligomer and a monomer as a structural unit represented by the above general formula (C) are copolymerized, and then an alkylsulfonic acid or a fluorine-substituted alkylsulfonic acid is introduced.

  Specific examples of precursor monomers that can be used in (Method C) and can be structural units represented by the above general formula (A) include dihalides described in JP-A-2005-36125. Can be mentioned. Specifically, 2,5-dichloro-4′-hydroxybenzophenone, 2,4-dichloro-4′-hydroxybenzophenone, 2,6-dichloro-4′-hydroxybenzophenone, 2,5-dichloro-2 ′, Examples thereof include 4′-dihydroxybenzophenone and 2,4-dichloro-2 ′, 4′-dihydroxybenzophenone. Moreover, the compound which protected the hydroxyl group of these compounds by the tetrahydropyranyl group etc. can be mention | raise | lifted. Further, those in which a hydroxyl group is replaced with a thiol group and those in which a chlorine atom is replaced with a bromine atom or an iodine atom can also be mentioned.

(Method C) A method of introducing an alkyl sulfonic acid group into a precursor polymer (having no sulfonic acid group) by the method described in JP-A-2005-60625. For example, it can be introduced by reacting the hydroxyl group of the precursor polymer with propane sultone, butane sultone, or the like.

It is desirable that at least one of the anode electrode and the cathode electrode contains a water repellent.
(Water repellent)
The water repellent enhances the water resistance of the electrode by repelling moisture. When the water repellent is included, the water repellency and water retention of the electrode are increased, and it is good in both low and high humidity conditions. Power generation performance can be obtained. As the water repellent used in the present invention,
(A) a fluorine-containing copolymer having a structural unit derived from (meth) acrylate containing a polyfluoroalkyl group (hereinafter referred to as “fluorine-containing copolymer (a)”), and
(B) A structural unit represented by the following general formula (5) derived from a fluorine-containing olefin monomer (hereinafter also referred to as “structural unit (5)”), and a general formula ( 6) selected from the group consisting of a fluorine-containing copolymer (hereinafter referred to as “fluorine-containing copolymer (b)”) having the structural unit (hereinafter also referred to as “structural unit (6)”). Contains at least one.

In formula (5), X ¹ is a fluorine atom, a fluoroalkyl group or a group represented by —OW ¹ (W ¹
Represents an alkyl group or a fluoroalkyl group. ).

In Formula (6), X ² represents a hydrogen atom or a methyl group, and X ³ represents a group represented by — (CH ₂ ) _h OW ² (W ² represents an alkyl group, a hydroxyalkyl group, a glycidyl group, or a fluoroalkyl group. H represents an integer of 0 to 2), a group represented by -OCOW ³ (W ³ represents an alkyl group, a hydroxyalkyl group or a glycidyl group), a carboxyl group or an alkoxycarbonyl group.

Hereinafter, the fluorine-containing copolymers (a) and (b) will be described more specifically.
<Fluorine-containing copolymer (a)>
The fluorine-containing copolymer (a) is a polyfluoroalkyl group (hereinafter referred to as “R ^f group”).
Having a structural unit derived from (meth) acrylate.

Here, the R ^f group refers to a group in which two or more hydrogen atoms of an alkyl group are substituted with fluorine atoms. 1-20 are preferable and, as for carbon number of ^Rf group, 4-16 are especially preferable. The R ^f group may have either a linear structure or a branched structure, and in the case of a branched structure, it is preferable that the branched portion is present at the terminal portion of the R ^f group. A part of carbon atoms of the R ^f group may be substituted with an etheric oxygen atom or a thioetheric sulfur atom. Further, the R ^f group may contain a halogen atom other than a fluorine atom (for example, a chlorine atom).

In addition, the R ^f group is preferably a perfluoroalkyl group in which all of the hydrogen atoms of the alkyl group are substituted with fluorine atoms from the viewpoint of ease of imparting water repellency to the electrode.
The fluorine-containing copolymer (a) is derived from an R ^f group-containing (meth) acrylate. As the R ^f group-containing (meth) acrylate, a compound represented by the following general formula (7) is preferable.
CH ₂ = C (R) COO-QR ^f (7)
In formula (7), R represents a hydrogen atom or a methyl group. Q represents a divalent organic group, preferably an alkylene group and a divalent organic group containing an alkylene group, and more preferably an alkylene group. Specifically, —CH ₂ CH ₂ —, —CH (CH ₃ ) CH ₂ —, —CH ₂ CH ₂ N (CH ₃ ) CO—, —CH ₂ CH ₂ N (CH ₃ ) SO ₂ —, — CH (CH ₂ Cl) CH ₂ OCH ₂ CH ₂ N (CH ₃ ) SO ₂ — and the like are preferable.

As described above, R ^f is preferably a perfluoroalkyl group, and particularly a linear structure of perfluoroalkyl group represented by C _n F _{2n + 1} — (wherein n represents an integer of 4 to 16, preferably 6 to 12). A fluoroalkyl group is preferred.

As the R ^f group-containing (meth) acrylate represented by the above formula (7), for example,
CH ₂ = CRCOOCH ₂ CH ₂ R ^f ,
CH ₂ = CRCOOCH (CH ₃ ) CH ₂ R ^f ,
CH ₂ = CRCOOCH ₂ CH ₂ N (CH ₃ ) COR ^f ,
CH ₂ = CRCOOCH ₂ CH ₂ N (C ₂ H ₅ ) COR ^f ,
CH ₂ = CRCOOCH ₂ CH ₂ N (C ₃ H ₇ ) COR ^f ,
_{CH 2 = CRCOOCH 2 CH 2 N} (CH 3) SO 2 R f,
_{CH 2 = CRCOOCH 2 CH 2 N} (C 2 H 5) SO 2 R f,
_{CH 2 = CRCOOCH 2 CH 2 N} (C 3 H 7) SO 2 R f,
_{CH 2 = CRCOOCH (CH 2 Cl} ) CH 2 OCH 2 CH 2 N (CH 3) SO 2 R f
However, the present invention is not limited to these.

The R ^f group-containing (meth) acrylate may be used alone or in combination of two or more. Moreover, you may use together 2 or more types of compounds from which carbon number of ^Rf group differs.
The fluorine-containing copolymer (a), for the purpose of, for example, adjusting the fluorine content in the polymer, R ^f
It is preferable to contain a polymerization unit derived from a monomer other than the group-containing (meth) acrylate (hereinafter referred to as “other monomer”).

  As said other monomer, the monomer which has a radically polymerizable unsaturated bond is preferable. Specifically, vinyl chloride, stearyl (meth) acrylate, ethylene, vinyl acetate, vinyl fluoride, halogenated vinyl styrene, α-methyl styrene, p-methyl styrene, (meth) acrylic acid, alkyl (meth) acrylate Esters, polyoxyalkylene (meth) acrylates, (meth) acrylamides, diacetone (meth) acrylamides, N-methylol (meth) acrylamides, vinyl alkyl ethers, halogenated alkyl vinyl ethers, vinyl alkyl ketones, butadiene, isoprene, chloroprene, glycidyl ( (Meth) acrylate, aziridinyl (meth) acrylate, benzyl (meth) acrylate, 2-isocyanatoethyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl ( Data) acrylate, maleic anhydride, having a polysiloxane (meth) acrylate, etc. N- vinyl carbazole. Among these, vinyl chloride and stearyl (meth) acrylate are particularly preferable (from the viewpoint of improving water repellency).

The polymer unit derived from the R ^f group-containing (meth) acrylate in the fluorine-containing copolymer (a) is contained in the range of 25 to 100% by weight, preferably 30 to 85% by weight of the polymer (a). It is desirable. Since the content of the polymer unit derived from the R ^f group-containing (meth) acrylate is within the above range, the electrode has an excellent balance of water repellency and water retention, and good power generation performance under both low and high humidity conditions. Can be obtained.

The fluorine-containing copolymer (a) is produced using the R ^f group-containing (meth) acrylate and, if necessary, other monomers, appropriately employing known or well-known polymerization methods and conditions. Can do.

  Examples of the polymerization method include a bulk polymerization method, a suspension polymerization method, an emulsion polymerization method, and a solution polymerization. Moreover, in addition to radical polymerization reaction, it can also manufacture by polymerization reactions, such as a radiation polymerization reaction and a photopolymerization reaction. In particular, an emulsion polymerization method using a radical polymerization reaction is preferable.

  In the case of applying the emulsion polymerization method, a method in which a monomer, a surfactant and the like are emulsified in the presence of water and then polymerized by stirring is preferably employed. Further, a method in which a monomer, a surfactant, water and the like are preliminarily emulsified using an emulsifier such as a homogenizer and then polymerized with stirring is preferably employed.

  As the polymerization initiator, various polymerization initiators such as organic acid peroxides, azo compounds and persulfates are preferable. In addition, as the surfactant, various anionic, cationic, amphoteric or nonionic surfactants can be used.

  The number average molecular weight (Mn) of the fluorine-containing copolymer (a) used in the present invention is preferably 1,000 to 100,000, particularly preferably 10,000 to 100,000. If the Mn of the fluorinated copolymer (a) is lower than the above range, it becomes difficult to impart water repellency to the electrode, and it tends to be difficult to obtain good power generation performance under high humidity conditions. On the other hand, when Mn of the fluorinated copolymer (a) exceeds the above range, the viscosity of the electrode paste is remarkably increased, and it tends to be difficult to produce an electrode.

<Fluorine-containing copolymer (b)>
The fluorine-containing copolymer (b) includes the structural unit (5) and the structural unit (6),
Preferably, it further includes a structural unit derived from a monomer containing a hydroxyl group (hereinafter also referred to as “hydroxyl group-containing structural unit”).

Examples of the fluoroalkyl group in X ¹ in the structural unit (5) include a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluorohexyl group, and a perfluorocyclohexyl group. A C1-C6 fluoroalkyl group is mentioned. Examples of the alkyl group for W ¹ include a methyl group,
C1-C6 alkyl groups, such as an ethyl group, a propyl group, a butyl group, a hexyl group, a cyclohexyl group, etc. are mentioned. Examples of the fluoroalkyl group in W ¹ include the same fluoroalkyl groups as in X ¹ .

Examples of the alkoxycarbonyl group for X ³ in the structural unit (6) include a methoxycarbonyl group and an ethoxycarbonyl group. Examples of the fluoroalkyl group for W ² in the structural unit (6) include the same fluoroalkyl groups for X ¹ in the structural unit (5). The alkyl group in W ² and W ³ in the structural unit (6) in, for example, mentioned a methyl group, an ethyl group, a propyl group, a hexyl group, a cyclohexyl group, an alkyl group having 1 to 12 carbon atoms such as lauryl group It is done. Examples of the hydroxyalkyl group in W ² and W ³ include 2-hydroxyethyl group, 2-hydroxypropyl group, 3-hydroxypropyl group, 4-hydroxybutyl group, 3-hydroxybutyl group, and 5-hydroxypentyl. Group, 6-hydroxyhexyl group and the like.

Examples of the fluorine-containing olefin monomer that can be the structural unit (5) include compounds having at least one polymerizable unsaturated double bond group and at least one fluorine atom. Specifically, fluoroolefins such as tetrafluoroethylene, hexafluoropropylene and 3,3,3-trifluoropropylene;
Alkyl perfluorovinyl ethers or fluoroalkyl perfluorovinyl ethers represented by the general formula CF ₂ ═CF—O—W ¹ (W ¹ is as defined above);
Perfluoro (alkyl vinyl ether) s such as perfluoro (methyl vinyl ether), perfluoro (ethyl vinyl ether), perfluoro (propyl vinyl ether), perfluoro (butyl vinyl ether), perfluoro (isobutyl vinyl ether); perfluoro (propoxypropyl vinyl ether) Perfluoro (alkoxyalkyl vinyl ethers) such as

  The said fluorine-containing olefin type monomer may be used individually by 1 type, or may use 2 or more types together. Among the fluorine-containing olefin monomers, hexafluoropropylene, perfluoroalkyl perfluorovinyl ether and perfluoro (alkoxyalkyl vinyl ether) are preferable, and it is more preferable to use these in combination.

  Content of the structural unit (5) in the said fluorine-containing copolymer (b) is 20-70 mol%, Preferably it is 25-60 mol%, More preferably, it is 30-55 mol%. If the content of the structural unit (5) is lower than the above range, the drainage property of the electrode tends to be inferior, and thus good power generation performance may not be obtained under high humidity conditions. On the other hand, when the above range is exceeded, the solubility of the resulting fluorine-containing copolymer (b) in an organic solvent is remarkably lowered, and it may be difficult to produce a uniform electrode paste.

As a vinyl ether monomer that can be the structural unit (6), for example,
Methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, n-pentyl vinyl ether, n-hexyl vinyl ether, n-octyl vinyl ether, n-dodecyl vinyl ether, 2-ethylhexyl Alkyl vinyl ethers or cycloalkyl vinyl ethers such as vinyl ether and cyclohexyl vinyl ether; vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl caproate, vinyl versatate, vinyl stearate, etc .; methyl (meta ) Acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, (Meth) acrylic acid esters such as butyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2- (n-propoxy) ethyl (meth) acrylate; (meth) acrylic Examples thereof include carboxyl group-containing compounds such as acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid.

  Content of the structural unit (6) in the said fluorine-containing copolymer (b) is 5-70 mol%, Preferably it is 10-60 mol%, More preferably, it is 20-50 mol%. When the content of the structural unit (6) is lower than the above range, the water retention in the electrode tends to be inferior, and thus good power generation performance may not be obtained under low humidity conditions. On the other hand, if the above range is exceeded, the drainage property of the electrode tends to be inferior, and thus good power generation performance may not be obtained under high humidity conditions.

  Examples of the monomer containing a hydroxyl group that can be a hydroxyl group-containing structural unit include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 3-hydroxybutyl vinyl ether, 5 Hydroxyl group-containing vinyl ethers such as hydroxypentyl vinyl ether and 6-hydroxyhexyl vinyl ether; hydroxyl group-containing allyl ethers such as 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether and glycerol monoallyl ether; allyl alcohol; ) Acrylic acid ester and the like. These compounds may be used alone or in combination of two or more.

  Content of the hydroxyl-containing structural unit in the said fluorine-containing copolymer (b) is 5-70 mol%, Preferably it is 10-60 mol%, More preferably, it is 20-50 mol%. When the content of the hydroxyl group-containing structural unit is lower than the above range, the water retention in the electrode tends to be inferior, and thus good power generation performance may not be obtained under low humidity conditions. On the other hand, if the above range is exceeded, the drainage property of the electrode tends to be inferior, and thus good power generation performance may not be obtained under high humidity conditions.

  In the production of the fluorine-containing copolymer (b), when the monomer containing the hydroxyl group is used, from the viewpoint of increasing the yield in the polymerization reaction, the vinyl ether monomers are alkyl vinyl ethers, cycloalkyl vinyl ethers. It is preferable to use carboxylic acid vinyl esters or carboxyl group-containing compounds. In particular, from the viewpoint of increasing the fluorine content copolymerized in the fluorine-containing copolymer (B), for example, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, vinyl acetate, vinyl propionate, vinyl butyrate, pivalin. Low molecular weight monomers such as vinyl acid are preferred.

  The fluorine content in the fluorine-containing copolymer (b) is 30 to 70% by weight, preferably 40 to 60% by weight. If the fluorine content is lower than the above range, the water repellency of the electrode may decrease, and good power generation performance may not be obtained under high humidity conditions. On the other hand, if the fluorine content exceeds the above range, the water retention of the electrode will decrease. However, good power generation performance may not be obtained under low humidity conditions. In addition, the said fluorine content measures the weight of a fluorine atom by the Alizari complexone method.

Mn of the fluorine-containing copolymer (b) is a value in terms of polystyrene measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent, and is 5,000 to 500,000, preferably 10,000. To 300,000, more preferably 10,000 to 100,000. If Mn is smaller than the above range, the water repellency of the electrode may be reduced, and good power generation performance may not be obtained under high humidity conditions. It can be difficult.

  The polymerization mode for producing the fluorine-containing copolymer (b) may be any of emulsion, suspension, bulk or solution polymerization in the presence of a radical polymerization initiator, and may be batch, semi-continuous or continuous. The operation can be selected as appropriate. As the radical polymerization initiator, azo group-containing polysiloxane can be used, but other radical initiators can also be used in combination.

Examples of other radical polymerization initiators that can be used in combination include:
Diacyl peroxides such as acetyl peroxide and benzoyl peroxide; ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; hydroperoxides such as hydrogen peroxide, tert-butyl hydroperoxide and cumene hydroperoxide; Dialkyl peroxides such as di-tert-butyl peroxide, dicumyl peroxide and dilauroyl peroxide; peroxy esters such as tert-butyl peroxyacetate and tert-butyl peroxypivalate; azobisisobutyro Azo compounds such as nitrile and azobisisovaleronitrile; persulfates such as ammonium persulfate, sodium persulfate and potassium persulfate; perfluoroethyl iodide, perfluoropropyl eye Dide, perfluorobutyl iodide, (perfluorobutyl) ethyl iodide, perfluorohexyl iodide, 2- (perfluorohexyl) ethyl iodide, perfluoroheptyl iodide, perfluorooctyl iodide, 2- (per Fluorooctyl) ethyl iodide, perfluorodecyl iodide, 2- (perfluorodecyl) ethyl iodide, heptafluoro-2-iodopropane, perfluoro-3-methylbutyl iodide, perfluoro-5-methylhexylio Dye, 2- (perfluoro-5-methylhexyl) ethyl iodide, perfluoro-7-methyloctyl iodide, 2- (perfluoro-7-methyloctyl) ethyl iodide, perfluoro-9 -Methyldecyl iodide, 2- (perfluoro-9-methyldecyl) ethyl iodide, 2,2,3,3-tetrafluoropropyl iodide, 1H, H, 5H-octafluoropentyl iodide, 1H, 1H, Examples thereof include iodine-containing fluorine compounds such as 7H-dodecafluoroheptyl iodide, tetrafluoro-1,2-diiodoethane, octafluoro-1,4-diiodobutane and dodecafluoro-1,6-diiodohexane.

  In addition, the radical polymerization initiator may be used in combination with an inorganic reducing agent such as sodium hydrogen sulfite and sodium pyrosulfite, and an organic reducing agent such as cobalt naphthenate and dimethylaniline as necessary.

  The production of the fluorinated copolymer (b) is preferably carried out in a solvent system using a solvent. Examples of the solvent include esters such as ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, and cellosolve; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; cyclic ethers such as tetrahydrofuran and dioxane; N Amides such as N, N-dimethylformamide and N, N-dimethylacetamide; aromatic hydrocarbons such as toluene and xylene, etc., and alcohols and aliphatic hydrocarbons may be mixed as necessary. Can also be used.

The catalyst particles in the formed electrode are contained in a proportion of 20 to 90% by weight, preferably 40 to 85% by weight, and the polymer electrolyte is a proportion of 5 to 60% by weight, preferably 10 to 50% by weight. Contained. Moreover, the water repellent used as needed is contained in the electrode in a proportion of 0 to 20 wt%, preferably 1 to 10 wt%, and the dispersant is 0 to 10 wt%, preferably 0 to 0 wt%.
It is desirable that the carbon fiber is contained in a proportion of 3% by weight, and the carbon fiber is contained in a proportion of 0 to 20% by weight, preferably 1 to 10% by weight (the total of these is 100% by weight).

  If the ratio of the catalyst particles is lower than the above range, the electrode reaction rate may decrease, and if it exceeds the above range, the proton conductivity efficiency may decrease, and the power generation performance in the electrode is sufficiently low. There is a tendency that the pore volume cannot be secured. If the ratio of the polymer electrolyte is lower than the above range, the proton conductivity tends to decrease, and the electrode may not be formed because it cannot function as a binder. The pore volume tends to decrease. When the ratio of the water repellent is within the above range, the wet state in the electrode can be appropriately maintained, and the power generation output is improved.

When the proportion of the dispersant is within the above range, an electrode paste excellent in storage stability can be obtained and an electrode excellent in dispersibility can be obtained. When the carbon fiber is within the above range, the pore volume is appropriately secured, the drainage is good, and the power generation output is improved.
(Iii) Organic solvent and water An organic solvent is usually used for the preparation of the electrode paste. The organic solvent is not particularly limited, but preferably has a boiling point (b.p.) of 75 to 250 ° C., and —O—, —OH, —CO—, —SO—, —SO ₂ —. , —COO—, —CONR— (wherein R is a hydrogen atom, a hydrocarbon group), an organic solvent having at least one kind of group can be used.

  If the boiling point of the organic solvent is less than the above range, the productivity of the coating may decrease due to the phenomenon that the drying property of the electrode paste is fast and the nozzle of the die is easily clogged. If the boiling point exceeds the above range, removal of the solvent becomes difficult, pores in the electrode are blocked, and power generation performance may be reduced.

Specific examples of the organic solvent include ethanol (bp 78.3 ° C), n-propyl alcohol (bp 97 ° C), 2-propanol (bp 82.4 ° C), 2- Methyl-2-propanol (bp 82.5 ° C.), 2-butanol (bp 99.5 ° C.), n-butyl alcohol (bp 117 ° C.), 2-methyl-1-propanol (Bp 108 ° C), 1-pentanol (bp 138 ° C), 2-pentanol (bp 119 ° C), 3-pentanol (bp 115 ° C), 2- Methyl-1-butanol (bp 129 ° C.), 3-methyl-1-butanol (bp 131 ° C.), 2-methyl-2-butanol (bp 102 ° C.), 3-methyl- 2-butanol (bp 112 ° C), 2,2-dimethyl 1-propanol (bp 113 ° C), cyclohexanol ( b.p. 161 ° C.), 1-hexanol (b.
p.157 ° C.), 2-methyl-1-pentanol (bp 148 ° C.), 2-methyl-2-
Pentanol (bp 121 ° C), 4-methyl-2-pentanol (bp 132 ° C), 2-ethyl-1-butanol (bp 147 ° C), 1-methylcyclohexanol ( b.
156), 2-methylcyclohexanol (bp 168 ° C), 3-methylcyclohexanol (bp 168 ° C), 4-methylcyclohexanol (bp 171 ° C), 1-octanol (Bp. 195 ° C), 2-octanol (bp 180 ° C), 2-ethyl-1-hexanol (bp 184 ° C), dioxane (bp 101 ° C), butyl ether (bp 140 ° C), phenyl ether (bp 187 ° C), isopentyl ether (bp 173 ° C), 1,2-dimethoxyethane (bp 85.2 ° C), diethoxyethane (b p.102 ° C), bis (2-methoxyethyl) ether (bp 160 ° C), bis (2-ethoxyethyl) ether (bp 189 ° C), cineol (bp 176 ° C) , Benzyl ethyl ether (bp 185 ° C.) , Anisole (bp 154 ° C), phenetole (bp 170 ° C), acetal (bp 104 ° C), methyl ethyl ketone (bp 79.6 ° C), 2-pentanone (bp .102 ° C.), 3-pentanone (bp 102 ° C.), cyclopentanone (bp 131 ° C.), cyclohexanone (bp 156 ° C.), 2-hexanone (bp 128 ° C.) 4-methyl-2-pentanone (bp 117 ° C.), 2-heptanone (bp 151 ° C.), 2,4-dimethyl-3-pentanone (bp 125 ° C.),
2-octanone (bp 173 ° C.), γ-butyrolactone (bp 204 ° C.), n-butyl acetate (bp 126 ° C.), isobutyl acetate (bp 126 ° C.), acetic acid sec-butyl (bp 112 ° C), pentyl acetate (bp 150 ° C), isopentyl acetate (bp 142 ° C), 3-methoxybutyl acetate (bp 173 ° C), butyric acid Methyl (bp 102 ° C), ethyl butyrate (bp 121 ° C), methyl lactate (bp 145 ° C), ethyl lactate (bp 155 ° C), butyl lactate (bp 185 ° C), 2-methoxyethanol (bp 125 ° C), 2-ethoxyethanol (bp 136 ° C), 2- (methoxymethoxy) ethanol (bp 168 ° C), 2-isopropoxy Ethanol (bp 142 ° C), 1-methoxy-2-propanol (bp 120 ° C), 1 Ethoxy-2-propanol (bp 132 ° C), dimethyl sulfoxide (bp 189 ° C), N-methylformamide (bp 185 ° C), N, N-dimethylformamide (bp 153) ), N, N-diethylformamide (bp 178 ° C.), N, N-dimethylacetamide (bp 166 ° C.), N-methyl-2-pyrrolidone (bp 202 ° C.), tetra Examples include methylurea (bp 177.5 ° C.), and these can be used in combination of one or more.

  The electrode paste may contain water as necessary. Examples of water include distilled water and ion exchange water. The addition of water has the effect of reducing heat generation during electrode paste preparation.

  The organic solvent and water are removed at a drying temperature of 20 ° C. to 180 ° C., preferably 50 ° C. to 160 ° C., and a drying time of 5 minutes to 600 minutes, preferably 30 minutes to 400 minutes. If necessary, it can be removed by immersion in water. The water immersion temperature is 5 ° C to 120 ° C, preferably 15 ° C to 95 ° C, and the water immersion time is 1 minute to 72 hours, preferably 5 minutes to 48 hours.

  The amount of the organic solvent used is 5 to 95% by weight, preferably 15 to 90% by weight, based on 100% by weight of the entire paste. The amount of water used as necessary is 0 to 70%. % By weight, preferably 2 to 30% by weight.

When the amount of the organic solvent used is within the above range, the composition becomes a paste and is suitable for handling. When the amount of water used is within the above range, heat generation during electrode paste preparation can be efficiently reduced.
(Iv) Dispersant The electrode paste may further optionally contain a dispersant.

The dispersant is added to improve the dispersibility, storage stability, and fluidity of the electrode paste, thereby improving the productivity when applying the paste during electrode formation.
Examples of the dispersant include oleic acid / N-methyltaurine, potassium oleate / diethanolamine salt, alkyl ether sulfate / triethanolamine salt, polyoxyethylene alkyl ether sulfate / triethanolamine salt, amine of special modified polyether ester acid Salts, amine salts of higher fatty acid derivatives, amine salts of specially modified polyester acids, amine salts of high molecular weight polyetherester acids, amine salts of specially modified phosphoric acid esters, high molecular weight polyester acid amidoamine salts, amidoamine salts of special fatty acid derivatives, higher Fatty acid alkylamine salts, high molecular weight polycarboxylic acid amidoamine salts, sodium laurate, sodium stearate, sodium oleate sodium lauryl sulfate, sodium cetyl sulfate Salt, sodium stearyl sulfate, sodium oleyl sulfate, lauryl ether sulfate, sodium alkylbenzene sulfonate, oil-soluble alkylbenzene sulfonate, α-olefin sulfonate, higher alcohol phosphate monoester disodium salt, higher Anionic surfactants such as alcohol phosphate diester disodium salt, zinc dialkyldithiophosphate,
Benzyldimethyl {2- [2- (P-1,1,3,3-tetramethylbutylphenoxy) ethoxy] ethyl} ammonium chloride, octadecylamine acetate, tetradecylamine acetate, octadecyltrimethylammonium chloride, beef tallow trimethyl Ammonium chloride, dodecyltrimethylammonium chloride, palm trimethylammonium chloride, hexadecyltrimethylammonium chloride, behenyltrimethylammonium chloride, palm dimethylbenzylammonium chloride, tetradecyldimethylbenzylammonium chloride, octadecyldimethylbenzylammonium chloride, dioleyldimethylammonium chloride, 1 -Hydroxyethyl-2-tallow imidazoline quaternary salt, 2 Hepta de Seni Lou hydroxyethyl imidazoline,
Stearamide ethyl diethylamine acetate, stearamide ethyl diethylamine hydrochloride, triethanolamine monostearate formate, alkyl pyridium salt, higher alkyl amine ethylene oxide adduct, polyacrylamide amine salt, modified polyacrylamide amine salt, perfluoroalkyl Cationic surfactants such as quaternary ammonium iodide, and dimethyl coconut betaine, dimethyl lauryl betaine, sodium laurylaminoethylglycine, sodium laurylaminopropionate, stearyl dimethyl betaine, lauryl dihydroxyethyl betaine, amide betaine, imidazolinium betaine , Lecithin, 3- [ω-fluoroaccanoyl-N-ethylamino] -1-sodium propanesulfonate, N- [3- (par (Luorooctanesulfonamido) propyl] -N, N-dimethyl-N-carboxymethylene ammonium betaine and other amphoteric surfactants, and coconut fatty acid diethanolamide (1: 2 type), coconut fatty acid diethanolamide (1: 1 type) , Bovine fatty acid diethanolamide (1: 2 type), bovine fatty acid diethanolamide (1: 1 type), oleic acid diethanolamide (1: 1 type), hydroxyethyl lauryl amine, polyethylene glycol lauryl amine, polyethylene glycol coconut amine, polyethylene Glycol stearylamine, polyethylene glycol tallowamine,
Polyethylene glycol beef tallow propylene diamine, polyethylene glycol dioleyl amine, dimethyl lauryl amine oxide, dimethyl stearyl amine oxide, dihydroxyethyl lauryl amine oxide, perfluoroalkyl amine oxide, polyvinyl pyrrolidone, higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, fatty acid Nonionic surfactants such as ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, fatty acid ester of glycerin, fatty acid ester of pentaerythritol, fatty acid ester of sorbit, fatty acid ester of sorbitan, fatty acid ester of sugar, and laurylamino Sodium propionate, stearyl dimethyl betaine, Amphoteric surfactants such as rildihydroxyethylbetaine can be mentioned, and these can be used in combination of one or more, preferably a surfactant having a basic group, more preferably anionic or A cationic surfactant, and more preferably a surfactant having a molecular weight of 5,000 to 30,000.

(V) Carbon fiber Furthermore, the electrode paste may contain carbon fiber as needed. As the carbon fiber used in the present invention, rayon-based carbon fiber, PAN-based carbon fiber, lignin pover-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, etc. can be used, preferably vapor-grown carbon fiber. Is used. When the electrode paste carbon fiber is contained, the pore volume of the electrode is increased, the gas diffusibility is improved, the flooding phenomenon due to the generated water can be improved, and the power generation performance can be improved.
[III. Ion conductive membrane]
The ion conductive film constituting the membrane-electrode assembly of the present invention is not particularly limited, and a known ion conductive film can be used. As the component constituting the ion conductive film, the polymer exemplified above is used. An electrolyte is preferred. The polymer electrolyte has an ion exchange capacity of 0.3 to 5.0 meq / g, preferably 0.5 to 4.0 meq / g.

  For the ion conductive membrane using the polymer electrolyte, for example, a composition for forming an ion conductive membrane is prepared using an organic solvent similar to the organic solvent used in the electrode paste, and the composition is applied on a substrate. It can be produced by a casting method in which it is cast and formed into a film. In addition to the polymer electrolyte and the organic solvent, the composition may contain an inorganic acid such as sulfuric acid and phosphoric acid, an organic acid containing a carboxylic acid, an appropriate amount of water, and the like.

  The polymer concentration in the composition is usually 5 to 40% by weight, preferably 7 to 25% by weight, although it depends on the molecular weight of the polymer electrolyte. If the polymer concentration is lower than the above range, it is difficult to increase the film thickness, and pinholes tend to be easily generated. On the other hand, if the polymer concentration exceeds the above range, the solution viscosity is too high to form a film, and the surface smoothness is reduced. May lack sexuality.

The solution viscosity of the above composition depends on the molecular weight of the copolymer and the polymer concentration.
000 to 100,000 mPa · s, preferably 3,000 to 50,000 mPa · s. If the solution viscosity is lower than the above range, the retention of the solution during processing is poor and may flow from the substrate.On the other hand, if it exceeds the above range, the viscosity is too high to be extruded from the die, Film formation by the casting method may be difficult.

  The above composition is prepared by, for example, mixing the above-described components at a predetermined ratio and mixing them using a conventionally known method, for example, a mixer such as a wafer blower, a homogenizer, a disperser, a paint conditioner, or a ball mill. Can do.

  The base material is not particularly limited as long as it is a base material used in a normal solution casting method. For example, a base material made of plastic or metal is used, and preferably heat such as polyethylene terephthalate (PET) film. A substrate made of a plastic resin is used. Moreover, the said electrode can also be used as a base material.

After film formation by the above casting method, a polymer electrolyte membrane can be obtained by drying at a temperature of 30 to 160 ° C., preferably 50 to 150 ° C. for 3 to 180 minutes, preferably 5 to 120 minutes. The dry film thickness is usually 10 to 100 μm, preferably 20 to 80 μm. If the solvent remains in the membrane after drying, the solvent may be removed by water extraction as necessary.
[Example]
EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples. In addition, sulfonic acid equivalent, molecular weight, and pore volume, strength ratio of platinum atom (atom derived from catalyst particles) / sulfur atom (atom derived from sulfonated polyarylene), fuel cell creation and power generation performance, and power generation The durability was evaluated as follows.
1. Sulfonic acid equivalent The polymer having the sulfonic acid group was washed with water until the water was neutral, thoroughly washed with water except for free remaining acid, dried, weighed a predetermined amount, THF / Phenolphthalein dissolved in a mixed solvent of water was used as an indicator, titration was performed using a standard solution of NaOH, and the sulfonic acid equivalent was determined from the neutralization point.
2. Measurement of Molecular Weight The molecular weight of polyarylene having no sulfonic acid group was determined by GPC using polystyrene (THF) as a solvent and the molecular weight in terms of polystyrene. The molecular weight of polyarylene having a sulfonic acid group was determined by GPC using polystyrene as a molecular weight using N-methyl-2-pyrrolidone (NMP) to which lithium bromide and phosphoric acid were added as a solvent.
3. Electrode pore volume Up to 50% of the total electrode weight in the thickness direction from the ion conductive membrane side to the electrode surface, the thickness direction from the electrode surface (joint surface with the electrode substrate) to the ion conductive membrane side Then, up to 50% of the total electrode weight was uniformly removed. The pore volume (V2) of this electrode was measured by mercury porosimetry.

On the other hand, the pore volume of all electrodes is measured in advance by the mercury intrusion method in advance, and V2 is subtracted from the pore volume of the electrode, so that the ion conductive membrane side from the electrode surface (joint surface with the electrode substrate) Find the electrode pore volume (V1) up to 50% of the total electrode weight in the thickness direction to (V2 / V1)
Was calculated.
4). Intensity ratio of platinum atom / sulfur atom In the thickness direction from the electrode surface to the ion conductive membrane side, the electrode up to 50% of the total electrode weight is 50% of the total electrode weight with a knife from the electrode surface side in the membrane-electrode assembly. % Was uniformly cut in the direction of the electrode surface and collected (measured W1).

Further, in the thickness direction from the ion conductive membrane side to the electrode direction, the electrode corresponding to 50% of the total electrode weight is the same method as the electrode, and further to the limit where the ion conductive membrane is not contaminated toward the ion conductive membrane side. It was scraped off with a scalpel and collected (measured W2). These electrodes are measured with a fluorescent X-ray apparatus (MagiX PRO manufactured by Spectris Co., Ltd.), and the intensities of atoms unique to the polymer electrolyte (sulfur atoms derived from sulfonic acid) and atoms derived from catalyst particles (platinum atoms) in the electrodes are obtained. The intensity ratio (W2 / W1) of sulfur atom / platinum atom (S / Pt) was calculated. The strength ratio was used as an index of the weight ratio of the polymer electrolyte / catalyst particles.
[Synthesis of sulfonated polyphenylene ether]
A synthesis example of a sulfonated polyarylene preferably used as a sulfonic acid group-containing aromatic polymer according to the present invention will be described. The present invention is not particularly limited to the following synthesis examples. However, when these sulfonated polyarylenes are used as an ion conductive group-containing polymer in an electrode or an ion exchange membrane, a fuel cell exhibiting good power generation characteristics. Can be obtained.
[Synthesis Example 1] (1) Synthesis of hydrophobic unit 48.8 g (284 mmol) of 2,6-dichlorobenzonitrile was added to a 1 L three-necked flask equipped with a stirrer, thermometer, Dean-Stark tube, nitrogen introduction tube, and cooling tube. ), 2,2-bis (4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane (89.5 g, 266 mmol) and potassium carbonate (47.8 g, 346 mmol). After nitrogen substitution, 346 mL of sulfolane and 173 mL of toluene were added and stirred. The reaction solution was heated to reflux at 150 ° C. in an oil bath. 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 200 ° C. and stirring was continued for 3 hours. Then, 9.2 g (53 mmol) of 2,6-dichlorobenzonitrile was added, and the reaction was further continued for 5 hours.

The reaction solution was allowed to cool, and diluted with 100 mL of toluene. Inorganic salts insoluble in the reaction solution were filtered, and the filtrate was poured into 2 L of methanol to precipitate the product. The precipitated product was filtered and dried, then dissolved in 250 mL of tetrahydrofuran, and poured into 2 L of methanol for reprecipitation. The precipitated white powder was filtered and dried to obtain 109 g of the desired product. The number average molecular weight (Mn) measured by GPC was 9,500. It was confirmed that the obtained compound was an oligomer represented by the formula (I).

(2) Synthesis of basic unit
Synthesis of 2,5-dichloro-4 '-(1-imidazolyl) benzophenone

In a 2 L three-necked flask equipped with a stirrer, a thermometer, a condenser tube, and a nitrogen inlet tube, 150.7 g (0.560 mol) of 2,5-dichloro-4′-fluorobenzophenone, imidazole 114
. 4 g (1.68 mol), 100.6 g (0.728 mol) of potassium carbonate, and 840 ml of N, N′-dimethylacetamide were weighed. The reaction solution was heated at 110 ° C. for 2 hours using an oil bath in a nitrogen atmosphere. After confirming disappearance of the raw material by thin layer chromatography, the reaction solution was allowed to cool to room temperature. Thereafter, the reaction solution was gradually added to 3 L of water to coagulate the product and filtered. The product obtained by filtration was dissolved in THF (1.2 L), and toluene (4
After adding L), it was washed with brine until the aqueous layer was neutral. After the organic layer was dried with magnesium sulfate, the solvent was distilled off by an evaporator. The crude yield was 180 g. Recrystallization isolation operation was performed using a mixed solvent of 1 L of toluene heated to 80 ° C. and 20 ml of methanol to obtain 155 g of white solid (III) in a yield of 87%.
(3) Synthesis of sulfonated polyarylene 540 mL of dried N, N-dimethylacetamide (DMAc) was mixed with 135.0 g (336 mmol) of neopentyl 3- (2,5-dichlorobenzoyl) benzenesulfonate (Synthesis Example 1). ), 40.7 g (5.6 mmol) of the hydrophobic unit (I) synthesized with 2,5-dichloro-4 ′-(1-imidazolyl) benzophenone of the basic unit (III).
71 g (16.8 mmol), bis (triphenylphosphine) nickel dichloride 6.71 g (10.3 mmol), triphenylphosphine 35.9 g (137 mmol), sodium iodide 1.54 g (10.3 mmol), A mixture of 53.7 g (821 mmol) 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 polymerization reaction solution was diluted with 730 mL of DMAc, stirred for 30 minutes, and filtered using Celite as a filter aid.

A part of the filtrate was poured into methanol and solidified. The molecular weight by GPC of the copolymer comprising a sulfonic acid derivative protected with a neopentyl group is Mn = 58000, Mw = 135,3.
00.

  The filtrate was concentrated with an evaporator, 43.8 g (505 mol) of lithium bromide was added to the filtrate, and the mixture was reacted at an internal temperature of 110 ° C. for 7 hours under a nitrogen atmosphere. After the reaction, the mixture was cooled to room temperature, poured into 4 L of acetone and solidified. The coagulated product was collected by filtration, air-dried, pulverized with a mixer, and washed with 1500 mL of 1N hydrochloric acid while stirring. After filtration, the product was washed with ion-exchanged water until the pH of the washing solution reached 5 or higher, and then dried at 80 ° C. overnight to obtain 23.0 g of the target sulfonated polymer. The molecular weight of the sulfonated polymer after this deprotection was Mn = 60000 and Mw = 175000. The ion exchange capacity of this polymer was 2.4 meq / g. The obtained polyarylene having a sulfonic acid group is a compound represented by the structural formula (IV).

[Example 1]
<Preparation of ion conductive membrane>
Into a 50 ml screw tube containing a stirrer, 4.5 g of the sulfonated polyarylene (II) obtained in Synthesis Example 1, 15.3 g of N-methyl-2-pyrrolidone, and 10.2 g of methanol were taken at room temperature. For 4 hours. This solution was cast on a pet film using a doctor blade, and dried at 60 ° C. for 1 hour and 120 ° C. for 1 hour using a thermostatic bath, and the solvent was distilled off. After drying, it was peeled off from the pet film to obtain a polymer electrolyte membrane having a thickness of 50 μm. In the following evaluation, power generation evaluation was performed using this film.

<Preparation of anode electrode paste>
In a 50 mL plastic bottle, 25 g of zirconia balls having a diameter of 10 mm (“YTZ balls” manufactured by Nikkato Co., Ltd.) are placed, 1.51 g of platinum-supported carbon particles (Pt: 50 wt% supported, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.), distilled water 0. 88 g, 4.28 g of an N-methyl-2-pyrrolidone solution (solid content: 15% by weight) of polymer (IV) of Synthesis Example 1 and 12.47 g of N-methyl-2-pyrrolidone were added, and the mixture was stirred for 60 minutes with a paint shaker. As a result, an anode electrode paste A was obtained.

<Preparation 1 of cathode electrode paste>
Platinum-supported carbon particles (Pt: 46 wt% supported, “TEC10E50E” manufactured by Tanaka Kikinzoku Co., Ltd.) 1.51 g in a 50 mL plastic bottle containing 25 g of zirconia balls having a diameter of 10 mm (“YTZ balls” manufactured by Nikkato Co., Ltd.) 0.88 g of distilled water, 3.23 g of N-methyl-2-pyrrolidone solution of polymer (IV) of Synthesis Example 1 (solid content 15% by weight), N-methyl-
Fluorine-containing copolymer B produced using 12.47 g of 2-pyrrolidone, vapor grown carbon fiber (“VGCF” manufactured by Showa Denko KK) 0.49, hexafluoropropylene and hydroxyethyl vinyl ether 0.8g of methyl ethyl ketone solution (solid content 15% by weight)
A cathode electrode paste B was obtained by adding a mixture of and stirring with a paint shaker for 60 minutes.

<Preparation 2 of cathode electrode paste>
Platinum-supported carbon particles (Pt: 46 wt% supported, “TEC10E50E” manufactured by Tanaka Kikinzoku Co., Ltd.) 1.51 g in a 50 mL plastic bottle containing 25 g of zirconia balls having a diameter of 10 mm (“YTZ balls” manufactured by Nikkato Co., Ltd.) 0.88 g of distilled water, 5.38 g of N-methyl-2-pyrrolidone solution of polymer (IV) of Synthesis Example 1 (solid content 15% by weight), N-methyl-
Of fluorinated copolymer B produced using a monomer containing 12.47 g of 2-pyrrolidone, vapor-grown carbon fiber (“VGCF” manufactured by Showa Denko KK) 0.49, hexafluoropropylene and hydroxyethyl vinyl ether 1.33 g of methyl ethyl ketone solution (solid content 15% by weight)
The mixture consisting of was put and stirred for 60 minutes with a paint shaker to obtain cathode electrode paste C.

<Production of electrode>
The anode electrode paste A is applied to one side of the ion conductive membrane prepared as described above with a doctor blade using a mask having an opening of 5 cm × 5 cm, and the surface to which the anode electrode paste A is not applied is applied. Cathode electrode paste C was applied after applying cathode electrode paste B with a doctor blade using a mask having an opening of 5 cm × 5 cm. By drying this at 120 ° C. for 60 minutes, the platinum coating amount of the anode electrode A is 0.30 mg / cm ² , the platinum coating amount of the cathode electrode B is 0.25 mg / cm ² , and the platinum coating amount of the cathode electrode C Anode electrode A and cathode electrode B with 0.25 mg / cm ²
C was formed.

The weight ratio of the polymer electrolyte / catalyst particles in the cathode electrode paste C used in the second layer to the weight ratio (P2) of the polymer electrolyte / catalyst particles in the cathode electrode paste B used in the first layer ( The ratio of P1) (P1 / P2) was 167%.

<Fabrication of fuel cell>
The electrolyte membrane in which the anode electrode A and the cathode electrode BC are formed on each surface is sandwiched between two water-repellent carbon papers so as to be in contact with the anode electrode A and the cathode electrode BC, and the pressure is 30 kg / cm. ² and hot press molding under the conditions of 160 ° C. × 15 min to produce a membrane-electrode assembly. The obtained electrode-membrane assembly was sandwiched between two titanium current collectors, and a heater was placed on the outside thereof to produce a fuel cell for evaluation having an effective area of 25 cm ² .
[Example 2]
<Preparation of anode electrode paste>
An anode electrode paste A was obtained in the same manner as in Example 1.

<Preparation 1 of cathode electrode paste>
Platinum-supported carbon particles (Pt: 46 wt% supported, “TEC10E50E” manufactured by Tanaka Kikinzoku Co., Ltd.) 1.51 g in a 50 mL plastic bottle containing 25 g of zirconia balls having a diameter of 10 mm (“YTZ balls” manufactured by Nikkato Co., Ltd.) , 0.88 g of distilled water, 4.00 g of an N-methyl-2-pyrrolidone solution of polymer (IV) of Synthesis Example 1 (solid content 15 wt%), N-methyl-
Of fluorine-containing copolymer B produced by using 12.47 g of 2-pyrrolidone, 0.82 g of vapor grown carbon fiber (“VGCF” manufactured by Showa Denko KK), a monomer containing hexafluoropropylene and hydroxyethyl vinyl ether A cathode electrode paste D was obtained by adding a mixture of 1.07 g of methyl ethyl ketone solution (solid content 15% by weight) and stirring for 60 minutes with a paint shaker.

<Preparation 2 of cathode electrode paste>
Platinum-supported carbon particles (Pt: 46 wt% supported, “TEC10E50E” manufactured by Tanaka Kikinzoku Co., Ltd.) 1.51 g in a 50 mL plastic bottle containing 25 g of zirconia balls having a diameter of 10 mm (“YTZ balls” manufactured by Nikkato Co., Ltd.) 0.88 g of distilled water, 4.62 g of N-methyl-2-pyrrolidone solution of polymer (IV) of Synthesis Example 1 (solid content 15% by weight), N-methyl-
Of fluorine-containing copolymer B produced by using 12.47 g of 2-pyrrolidone, 0.49 g of vapor grown carbon fiber (“VGCF” manufactured by Showa Denko KK), a monomer containing hexafluoropropylene and hydroxyethyl vinyl ether A mixture composed of 1.07 g of a methyl ethyl ketone solution (solid content: 15% by weight) was added, and the mixture was stirred for 60 minutes with a paint shaker to obtain cathode electrode paste E.

<Manufacture of electrodes>
Except that the anode electrode paste D and cathode electrode pastes D and E obtained as described above were used (the cathode electrode paste D was first applied and then the cathode electrode paste E was applied), the same as in Example 1. Thus, an anode electrode A and a cathode electrode DE were formed.

The weight ratio of the polymer electrolyte / catalyst particles in the cathode electrode paste E used in the second layer to the weight ratio (P2) of the polymer electrolyte / catalyst particles in the cathode electrode paste D used in the first layer ( The ratio of P1) (P1 / P2) was 116%.

<Fabrication of fuel cell>
A fuel cell for evaluation was produced in the same manner as in Example 1 except that the anode electrode A and the cathode electrode DE obtained as described above were used.
[Example 3]
<Preparation of anode electrode paste 1>
In a 50 mL plastic bottle containing 25 g of zirconia balls having a diameter of 10 mm (“YTZ balls” manufactured by Nikkato Co., Ltd.), 1.51 g of platinum-supported carbon particles (Pt: 50 wt% supported, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.), distilled water 0.88 g, a mixture consisting of N-methyl-2-pyrrolidone solution (solid content 15% by weight) of polymer (IV) of Synthesis Example 1 (solid content 15% by weight), and N-methyl-2-pyrrolidone 12.47 g were put into a paint shaker. Was stirred for 60 minutes to obtain anode electrode paste F.

<Preparation 2 of anode electrode paste>
In a 50 mL plastic bottle containing 25 g of zirconia balls having a diameter of 10 mm (“YTZ balls” manufactured by Nikkato Co., Ltd.), 1.51 g of platinum-supported carbon particles (Pt: 50 wt% supported, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.), distilled water A mixture of 0.88 g, 5.38 g of an N-methyl-2-pyrrolidone solution of the polymer (IV) of Synthesis Example 1 (solid content 15% by weight) and 12.47 g of N-methyl-2-pyrrolidone was added, and a paint shaker was added. Was stirred for 60 minutes to obtain an anode electrode paste G.

<Preparation 1 of cathode electrode paste>
Cathode electrode paste B was obtained in the same manner as Example 1.
<Preparation 2 of cathode electrode paste>
Cathode electrode paste C was obtained in the same manner as Example 1.

<Production of electrode>
The anode electrode paste F was applied to one side of the ion conductive film prepared as described above with a doctor blade using a mask having an opening of 5 cm × 5 cm, and the anode electrode paste G was applied thereon. In addition, the cathode electrode paste C was applied on the surface on which the anode electrode pastes F and G were not applied, using a mask having an opening of 5 cm × 5 cm, and applying the cathode electrode paste B with a doctor blade. By drying this at 120 ° C. for 60 minutes, the platinum coating amount of the anode electrode F is 0.15 mg / cm ² , the platinum coating amount of the anode electrode G is 0.15 mg / cm ² , and the platinum coating amount of the cathode electrode B Is 0.25m
An anode electrode FG and a cathode electrode BC having g / cm ² and a platinum coating amount of 0.25 mg / cm ² on the cathode electrode C were formed.

The weight ratio of the polymer electrolyte / catalyst particles in the anode electrode paste G used in the second layer to the weight ratio (P2) of the polymer electrolyte / catalyst particles in the anode electrode paste F used in the first layer ( The ratio of P1) (P1 / P2) was 167%.

<Fabrication of fuel cell>
A fuel cell for evaluation was produced in the same manner as in Example 1 except that the anode electrode FG and the cathode electrode BC obtained as described above were used.
[Comparative Example 1]
<Preparation of anode electrode paste>
An anode electrode paste A was obtained in the same manner as in Example 1.

<Preparation of cathode electrode paste>
Cathode electrode paste E was obtained in the same manner as Example 2.
<Production of electrode>
The anode electrode paste A is applied to one side of the ion conductive membrane prepared as described above with a doctor blade using a mask having an opening of 5 cm × 5 cm, and the surface to which the anode electrode paste A is not applied is applied. Cathode electrode paste E was applied with a doctor blade using a mask having an opening of 5 cm × 5 cm. By drying this at 120 ° C. for 60 minutes, the anode coating amount of the anode A is 0.30 mg / cm ² and the cathode coating amount of the cathode E is 0.50 mg / cm ^2. E was formed (both only one layer).

<Fabrication of fuel cell>
A fuel cell for evaluation was produced in the same manner as in Example 1 except that the anode electrode A and the cathode electrode E obtained as described above were used.

[Comparative Example 2]
<Preparation of anode electrode paste>
An anode electrode paste A was obtained in the same manner as in Example 1.

<Preparation 1 of cathode electrode paste>
Platinum-supported carbon particles (Pt: 46 wt% supported, “TEC10E50E” manufactured by Tanaka Kikinzoku Co., Ltd.) 1.51 g in a 50 mL plastic bottle containing 25 g of zirconia balls having a diameter of 10 mm (“YTZ balls” manufactured by Nikkato Co., Ltd.) 0.88 g of distilled water, 1.09 g of N-methyl-2-pyrrolidone solution of polymer (IV) of Synthesis Example 1 (solid content 15% by weight), N-methyl-
Fluorine-containing copolymer B produced using 12.47 g of 2-pyrrolidone, vapor grown carbon fiber (“VGCF” manufactured by Showa Denko KK) 0.49, hexafluoropropylene and hydroxyethyl vinyl ether A mixture of 0.27 g of methyl ethyl ketone solution (solid content 15% by weight) was added and stirred for 60 minutes with a paint shaker to obtain cathode electrode paste H.

<Preparation 2 of cathode electrode paste>
Platinum-supported carbon particles (Pt: 46 wt% supported, “TEC10E50E” manufactured by Tanaka Kikinzoku Co., Ltd.) 1.51 g in a 50 mL plastic bottle containing 25 g of zirconia balls having a diameter of 10 mm (“YTZ balls” manufactured by Nikkato Co., Ltd.) , 0.88 g of distilled water, 7.50 g of N-methyl-2-pyrrolidone solution of polymer (IV) of Synthesis Example 1 (solid content 15% by weight), N-methyl-
Of fluorinated copolymer B produced using a monomer containing 12.47 g of 2-pyrrolidone, vapor-grown carbon fiber (“VGCF” manufactured by Showa Denko KK) 0.49, hexafluoropropylene and hydroxyethyl vinyl ether 1.86 g of methyl ethyl ketone solution (solid content 15% by weight)
A cathode electrode paste I was obtained by adding a mixture of and stirring with a paint shaker for 60 minutes.

<Production of electrode>
The anode electrode paste A is applied to one side of the ion conductive membrane prepared as described above with a doctor blade using a mask having an opening of 5 cm × 5 cm, and the surface to which the anode electrode paste A is not applied is applied. Cathode electrode paste I was applied after applying cathode electrode paste H with a doctor blade using a mask having an opening of 5 cm × 5 cm. By drying this at 120 ° C. for 60 minutes, the platinum coating amount of the anode electrode A is 0.30 mg / cm ² , the platinum coating amount of the cathode electrode H is 0.25 mg / cm ² , and the platinum coating amount of the cathode electrode I Anode electrode HI and cathode electrode HI with a 0.25 mg / cm ²
Formed.

The weight ratio of the polymer electrolyte / catalyst particles in the cathode electrode paste I used in the second layer to the weight ratio (P2) of the polymer electrolyte / catalyst particles in the cathode electrode paste H used in the first layer ( The ratio of P1) (P1 / P2) was 688%.

<Fabrication of fuel cell>
A fuel cell for evaluation was produced in the same manner as in Example 1 except that the anode electrode A and the cathode electrode HI obtained as described above were used.
[Evaluation]
It shows about the evaluation method of the fuel cell obtained in Examples 1-3 and Comparative Examples 1-4.
Evaluation 1
The temperature is maintained at 80 ° C., and the anode and cathode are supplied with 2 atmospheres of hydrogen and air (under a constant back pressure of 0.2 MPa) under conditions of humidity 40% RH and 80% RH, and a current density of 0.2 A.
The voltage between terminals at / cm ² and 0.8 A / cm ² was measured. The results are shown in Table 1.
Evaluation 2
After measuring evaluation 1, the temperature of the fuel cell was kept at 120 ° C., and durability evaluation was performed under the condition of humidity 40% RH. Hydrogen and air are supplied at 2 atm (under a constant back pressure of 0.2 MPa), and the time until the terminal voltage becomes 0.3 V or less when the current density is maintained at 0.2 A / cm ² is determined. It was measured. The results are shown in Table 2.

FIG. 1 is a schematic diagram for explaining evaluation of pore volume and weight distribution in an electrode according to the present invention.

Claims (9)

A membrane-electrode assembly having an ion conductive membrane, and an anode electrode and a cathode electrode each containing catalyst particles and a polymer electrolyte on both sides of the ion conductive membrane,
At least one of the anode electrode and the cathode electrode, in the thickness direction from the electrode surface to the ion conductive membrane side, with respect to the pore volume (V1) in the electrode up to 50% of the total electrode weight, the ion conductive membrane side A membrane characterized in that, in the thickness direction from the electrode surface to the electrode surface, the ratio (V2 / V1) of the pore volume (V2) in the electrode up to 50% of the total electrode weight is 85% or more and less than 100% Electrode assembly.   The electrode has a total electrode weight in the thickness direction from the ion conductive membrane side to the weight ratio (W1) of the polymer electrolyte / catalyst particles in the electrode up to 50% of the total electrode weight in the thickness direction from the surface. 2. The ratio (W2 / W1) of the weight ratio (W2 / W1) of the polymer electrolyte / catalyst particles in the electrode up to 50% is greater than 100% and not more than 130%. Membrane-electrode assembly.   The membrane-electrode assembly according to claim 1 or 2, wherein at least one of the anode electrode and the cathode electrode is formed of a plurality of layers.   The polymer electrolyte used for at least one of the ion conductive membrane, the anode electrode, and the cathode electrode is formed by covalently bonding a polymer segment (A) having an ion conductive component and a polymer segment (B) having no ion conductive component. The membrane-electrode assembly according to any one of claims 1 to 3, which is a block copolymer.   The main chain skeleton forming a polymer electrolyte used for at least one of the ion conductive membrane, the anode electrode, and the cathode electrode has a structure in which an aromatic ring is covalently bonded with a bonding group. The membrane-electrode assembly according to any one of the above. The polymer electrolyte used for at least one of the ion conductive membrane, the anode electrode, and the cathode electrode is a sulfonic acid group-containing polyarylene having a structure represented by the following general formula (1). 6. The membrane-electrode assembly according to any one of 5 above.

[In the formula (1), Y represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) _i — (i represents an integer of 1 to 10). Or —C (CF ₃ ) ₂ —, Z is independently a direct bond, — (CH ₂ ) _j — (j represents an integer of 1 to 10), —C (CH ₃ ) ₂ —, — O— or —S— is represented, and Ar represents —SO ₃ H, —O (CH ₂ ) _p SO ₃ H or —O (CF ₂ ) _p SO ₃ H (p represents an integer of 1 to 12). The aromatic group which has a substituent represented by this is shown, m shows the integer of 0-10, n shows the integer of 0-10, k shows the integer of 1-4.
A and D are each independently a direct bond, —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) _i — (i represents an integer of 1 to 10. ), — (CH ₂ ) _j — (j represents an integer of 1 to 10), —CR ′ ₂ — (R ′ represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group or a halogenated hydrocarbon group. ), Cyclohexylidene group, fluorenylidene group, —O— or —S—, B is independently an oxygen atom or sulfur atom, and R ^{1 to} R ¹⁶ are each independently hydrogen atom, fluorine atom, alkyl Group, a halogenated alkyl group, allyl group, aryl group, nitro group or nitrile group partially or wholly halogenated, s and t each represent an integer of 0 to 4, and r is 0 or 1 or more Indicates an integer.
Z represents a direct bond or at least one structure selected from the group consisting of —O— and —S—, and Y represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO. —, — (CF ₂ ) ₁ — (wherein 1 is an integer of 1 to 10), —C (CF ₃ ) ₂ —, at least one structure selected from the group consisting of R ²⁰ represents a nitrogen-containing complex A ring group is shown. q represents an integer of 1 to 5, and p represents an integer of 0 to 4. x, y, z represents a molar ratio when x + y + z = 100 mol%. ] As a water repellent, at least one of the anode electrode and the cathode electrode,
(A) a fluorine-containing copolymer having a structural unit derived from (meth) acrylate containing a polyfluoroalkyl group, and / or (B) represented by the following general formula (2) derived from a fluorine-containing olefin monomer. And a fluorine-containing copolymer having a structural unit represented by the following general formula (3) derived from a vinyl ether monomer :

[In Formula (2), X ¹ represents a fluorine atom, a fluoroalkyl group or a group represented by —OW ¹ (W ¹ represents an alkyl group or a fluoroalkyl group). ]

[In the formula (3), X ² represents a hydrogen atom or a methyl group, and X ³ represents a group represented by — (CH ₂ ) _h OW ² (W ² represents an alkyl group, a hydroxyalkyl group, a glycidyl group or a fluoroalkyl group. H represents an integer of 0 to 2), a group represented by -OCOW ³ (W ³ represents an alkyl group, a hydroxyalkyl group or a glycidyl group), a carboxyl group or an alkoxycarbonyl group. . ]
The membrane-electrode assembly according to any one of claims 1 to 6, comprising:   The at least one of an anode electrode and a cathode electrode is formed of a plurality of layers, and (V2 / V1) of the electrode formed of a plurality of layers is 85% or more and less than 100%. The membrane-electrode assembly according to any one of 1 to 7.   A method for producing a membrane-electrode assembly in which an electrode paste containing a polymer electrolyte and catalyst particles is applied at least twice on an ion conductive membrane, the polymer electrolyte / catalyst in the electrode paste used in the first layer The ratio (P1 / P2) of the weight ratio (P1 / P2) of the polymer electrolyte / catalyst particles in the electrode paste used in the second layer or more to the weight ratio (P2) of the particles is 110% or more and 400% or less. A method for producing a membrane-electrode assembly, characterized by using a certain thing.

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