JP5522239B2 - Manufacturing method of membrane electrode assembly for polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to a method for producing a membrane electrode assembly for a polymer electrolyte fuel cell.

  A polymer electrolyte fuel cell has a membrane electrode assembly in which electrodes (cathode (air electrode) and anode (fuel electrode)) are arranged on both sides of a polymer electrolyte membrane, and a conductive separator in which a gas flow path is formed. Via multiple stacks. The electrode is composed of a catalyst layer in contact with the polymer electrolyte membrane, and a porous gas diffusion layer disposed outside the catalyst layer. The gas diffusion layer plays a role of diffusing air or fuel gas into the electrode and a role of draining water generated in the electrode.

The following methods are known as a method for producing a membrane electrode assembly.
(1) A coating solution containing an electrode catalyst and an ion exchange resin is applied on the gas diffusion layer to form a catalyst layer, which is used as an electrode, and heat is applied with a polymer electrolyte membrane sandwiched between the two electrodes. A method of joining by pressing (Patent Document 1).
(2) A coating solution containing an electrode catalyst and an ion exchange resin is coated on the substrate film and dried to form a first catalyst layer, and the ion exchange resin is contained on the first catalyst layer. A coating solution is applied and dried to form a polymer electrolyte membrane. A coating solution containing an electrode catalyst and an ion exchange resin is applied onto the polymer electrolyte membrane and dried to form a second catalyst layer. The base film is peeled from the laminate including the first catalyst layer, the polymer electrolyte membrane, and the second catalyst layer, and the laminate is sandwiched between the two gas diffusion layers. A method of joining by pressing (Patent Document 2).

  However, in the method (1), a coating liquid in which an electrode catalyst and an ion exchange resin are dispersed in a solvent is applied directly on the gas diffusion layer to form a catalyst layer. A part of the exchange resin and the catalyst enters, and part of the gap of the gas diffusion layer is blocked. In particular, the ion exchange resin easily penetrates from the catalyst layer into the gas diffusion layer together with the solvent. As a result, the gas diffusibility of the gas diffusion layer is lowered, and the output voltage of the polymer electrolyte fuel cell becomes insufficient in a high current density region.

In addition, since the electrode obtained by the method (1) has a small amount of ion exchange resin present in the catalyst layer, the catalyst layer and the polymer electrolyte membrane are not sufficiently bonded during hot pressing. As a result, the following problems occur.
(I) The resistance at the interface between the catalyst layer and the polymer electrolyte membrane increases.
(Ii) Since the polymer electrolyte membrane tends to swell and shrink due to humidification, the interface between the catalyst layer and the polymer electrolyte membrane tends to peel off when humidification and drying are repeated. Less resistance.

  In the method (2), since the polymer electrolyte membrane is formed directly on the first catalyst layer by coating, a part of the ion exchange resin enters the first catalyst layer, Many of the voids in the catalyst layer are blocked. As a result, the gas diffusibility of the first catalyst layer is lowered, and the output voltage of the polymer electrolyte fuel cell is insufficient in a high current density region.

Japanese Patent Laid-Open No. 04-162365 International Publication No. 02/005371 Pamphlet

  The present invention provides a method capable of producing a membrane electrode assembly for a polymer electrolyte fuel cell, which can obtain a high output voltage in a wide range of current densities and is excellent in resistance to humidity fluctuation.

The method for producing a membrane electrode assembly for a polymer electrolyte fuel cell according to the present invention includes a first electrode having a release layer, a catalyst layer, and a gas diffusion layer in this order, and a second electrode having a catalyst layer and a gas diffusion layer. , A method for producing a membrane electrode assembly for a polymer electrolyte fuel cell comprising a polymer electrolyte membrane disposed between a release layer of the first electrode and a catalyst layer of the second electrode, The step (a ′), the step (b), the step (c) and the step (g) are characterized in that
(A ′) A step of applying a coating liquid containing an electrode catalyst and an ion exchange resin on the release layer formed on the surface of the base film to form a coating liquid layer.
(B) A step of applying a gas diffusion layer on the coating liquid layer formed in step (a ′) and then drying the coating liquid layer to form a catalyst layer.
(C) The process of peeling a base film from the said peeling layer and obtaining the said 1st electrode after a process (b).
(G) The first electrode obtained in step (c), the second electrode, and the polymer electrolyte membrane are brought into contact with the release layer of the first electrode and the polymer electrolyte membrane. And a step of heat bonding so that the catalyst layer of the second electrode and the polymer electrolyte membrane are in contact with each other.

The method for producing a membrane electrode assembly for a polymer electrolyte fuel cell according to the present invention includes a first electrode having a release layer, a catalyst layer, and a gas diffusion layer in this order, and a first electrode having a release layer, a catalyst layer, and a gas diffusion layer in this order. And a polymer electrolyte membrane disposed between the release layer of the first electrode and the release layer of the second electrode, and a method for producing a membrane electrode assembly for a polymer electrolyte fuel cell It has the following steps (a ′) and (b) to (g).
(A ′) A step of applying a coating liquid containing an electrode catalyst and an ion exchange resin on the release layer formed on the surface of the base film to form a coating liquid layer.
(B) A step of applying a gas diffusion layer on the coating liquid layer formed in step (a ′) and then drying the coating liquid layer to form a catalyst layer.
(C) The process of peeling a base film from the said peeling layer and obtaining the said 1st electrode after a process (b).
(D ′) A step of applying a coating liquid containing an electrode catalyst and an ion exchange resin on the release layer formed on the surface of the substrate film to form a coating liquid layer.
(E) A step of applying a gas diffusion layer on the coating liquid layer formed in the step (d ′) and then drying the coating liquid layer to form a catalyst layer.
(F) After the step (e), a step of peeling the base film from the release layer to obtain the second electrode.
(G) The first electrode obtained in the step (c), the second electrode obtained in the step (f), and the polymer electrolyte membrane are in contact with the release layer and the polymer electrolyte membrane. Step of heat bonding.

The release layer is intended to facilitate removal from the substrate without breaking the catalyst layer formed on the release layer. Examples of the release layer material include release properties such as silicone resins, fluorine resins, and surfactants. High material is used. However, in order to join the release layer to the polymer electrolyte membrane in a later step, the release layer preferably contains an ion exchange resin, and particularly preferably contains a fluorine ion exchange resin as a main component. When ion exchange resin is not included as a main component, the thickness of the release layer is preferably as thin as possible, and is preferably 0.3 μm or less. When ion exchange resin is mainly contained, the thickness of the release layer is preferably 0.1 to 5 μm.
The electrode catalyst contains a noble metal, and the amount of the noble metal per unit area of the catalyst layer is preferably 0.01 to 0.5 mg / cm ² .

  According to the method for producing a membrane / electrode assembly for a polymer electrolyte fuel cell of the present invention, a high output voltage is obtained in a wide range of current densities and a high output voltage is obtained. A membrane electrode assembly can be manufactured.

It is sectional drawing which shows an example of the membrane electrode assembly for polymer electrolyte fuel cells. It is sectional drawing which shows 1 process of the manufacturing method of the membrane electrode assembly for polymer electrolyte fuel cells of this invention. It is sectional drawing which shows 1 process of the manufacturing method of the membrane electrode assembly for polymer electrolyte fuel cells of this invention. It is sectional drawing which shows the other example of the membrane electrode assembly for polymer electrolyte fuel cells. It is sectional drawing which shows 1 process of the manufacturing method of the membrane electrode assembly for polymer electrolyte fuel cells of this invention. It is sectional drawing which shows the other example of the membrane electrode assembly for polymer electrolyte fuel cells.

  In this specification, a compound represented by the formula (2) is referred to as a compound (2). The same applies to compounds represented by other formulas.

[First Embodiment]
FIG. 1 is a cross-sectional view showing an example of a membrane electrode assembly for a polymer electrolyte fuel cell (hereinafter referred to as a membrane electrode assembly). The membrane electrode assembly 10 includes a first electrode 20 having a catalyst layer 12 and a gas diffusion layer 14, a second electrode 30 having a catalyst layer 12 and a gas diffusion layer 14, a first electrode 20 and a second electrode. A polymer electrolyte membrane 40 interposed between the electrode 30 and the catalyst layer 12 is provided.

  The first electrode 20 may be an anode or a cathode. The second electrode 30 is a cathode when the first electrode 20 is an anode, and is an anode when the first electrode 20 is a cathode.

(Catalyst layer)
The catalyst layer 12 includes an electrode catalyst and an ion exchange resin.
The electrode catalyst preferably contains a noble metal. As the noble metal, platinum or a platinum alloy is preferable.
As the electrode catalyst, a supported catalyst in which platinum or a platinum alloy is supported on a carbon support is preferable.

Examples of the carbon carrier include activated carbon and carbon black.
The specific surface area of the carbon support is preferably 200 m ² / g or more. The specific surface area of the carbon support is measured by nitrogen adsorption on the carbon surface using a BET specific surface area apparatus.

Platinum alloys include platinum group metals other than platinum (ruthenium, rhodium, palladium, osmium, iridium), gold, silver, chromium, iron, titanium, manganese, cobalt, nickel, molybdenum, tungsten, aluminum, silicon, zinc And an alloy of one or more metals selected from the group consisting of tin and platinum. The platinum alloy may contain a metal alloyed with platinum and an intermetallic compound of platinum.
As the platinum alloy for the anode, when a fuel gas containing carbon monoxide is supplied to the anode, an alloy containing platinum and ruthenium is preferable from the viewpoint of the activity stability of the electrode catalyst.
The supported amount of platinum or platinum alloy is preferably 10 to 80% by mass in the electrode catalyst (100% by mass).

The ion exchange capacity of the ion exchange resin is preferably 0.5 to 2.5 meq / g dry resin, particularly 1.0 to 2.0 meq / g dry resin from the viewpoint of conductivity and gas diffusibility. preferable.
Examples of the ion exchange resin include a fluorine-containing ion exchange resin and a non-fluorine ion exchange resin, and the fluorine-containing ion exchange resin is preferable from the viewpoint of durability.

  As the fluorinated ion exchange resin having an ionic group, a perfluorocarbon polymer having a sulfonic acid group (which may contain an etheric oxygen atom) is preferable, and tetrafluoroethylene (hereinafter referred to as TFE) is preferred. A copolymer having a base unit and a repeating unit having a sulfonic acid group (hereinafter referred to as copolymer H) is particularly preferred. The repeating unit having a sulfonic acid group is preferably a repeating unit represented by the following formula (1).

  However, X is a fluorine atom or a trifluoromethyl group, m is an integer of 0 to 3, n is an integer of 1 to 12, and p is 0 or 1.

Copolymer H is obtained by polymerizing a mixture of monomers having TFE and -SO ₂ F groups to obtain precursor polymer F, and then converting -SO ₂ F groups in precursor polymer F to sulfonic acid groups. Is obtained. Conversion of the —SO ₂ F group into a sulfonic acid group is performed by hydrolysis and acidification treatment.

As the monomer having a —SO ₂ F group, the compound (2) is preferable.
_{CF 2 = CF (OCF 2 CFX} ) m -O p - (CF 2) n -SO 2 F ··· (2).
However, X is a fluorine atom or a trifluoromethyl group, m is an integer of 0-3, and n is an integer of 1-12.

As the compound (2), compounds (2-1) to (2-3) are preferable.
CF ₂ = CFO (CF ₂ ) _q SO ₂ F (2-1),
CF ₂ = CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) _r SO ₂ F (2-2),
_{CF 2 = CF (OCF 2 CF} (CF 3)) t O (CF 2) s SO 2 F ··· (2-3).
However, q, r, and s are integers of 1 to 8, and t is an integer of 1 to 3.

  Non-fluorinated ion exchange resins include sulfonated polyarylene, sulfonated polybenzoxazole, sulfonated polybenzothiazole, sulfonated polybenzimidazole, sulfonated polysulfone, sulfonated polyethersulfone, sulfonated polyetherethersulfone, sulfone. Polyphenylene sulfone, sulfonated polyphenylene oxide, sulfonated polyphenylene sulfoxide, sulfonated polyphenylene sulfide, sulfonated polyphenylene sulfide sulfone, sulfonated polyether ketone, sulfonated polyether ether ketone, sulfonated polyether ketone ketone, sulfonated polyimide, etc. Can be mentioned.

The mass ratio (F / C) of the mass (F) of the ion exchange resin and the mass (C) of the carbon in the electrode catalyst is preferably 0.2 to 2.5 from the viewpoint of electrode conductivity and water repellency. 0.7 to 2.0 is more preferable. If F / C is 0.2 or more, the catalyst layer 12 is difficult to break. If F / C is 2.5 or less, the catalyst layer 12 does not have a dense structure, and gas diffusibility is good.
The catalyst layer 12 may be a single layer or a plurality of layers. In the case of a plurality of layers, it is preferable that the F / C of each layer be gradually increased as it approaches the polymer electrolyte membrane 40.

The amount of the noble metal per unit area of the catalyst layer 12 is preferably from 0.01 to 0.5 / cm ^2, more preferably ^{0.05~0.4mg / cm 2, 0.1~0.3mg / cm} 2 Is particularly preferred. When the amount of the noble metal is 0.01 mg / cm ² or more, the amount of the coating solution when applying the coating solution on the base film is not too small, and the coating solution layer is stabilized. When the amount of the noble metal is 0.5 mg / cm ² or less, the amount of the coating solution does not increase excessively, the infiltration of the coating solution into the gas diffusion layer 14 is suppressed, and the catalyst layer 12 is not easily broken. When the amount of the noble metal is 0.05 to 0.4 mg / cm ² , the amount of the coating liquid is an appropriate amount, so that the catalyst layer 12 having a uniform thickness can be formed. If the amount of the noble metal is 0.1 to 0.3 mg / cm ² , the penetration of the coating liquid into the gas diffusion layer 14 and the cracking of the catalyst layer 12 are sufficiently suppressed.

  The thickness of the catalyst layer 12 is preferably 20 μm or less and more preferably 1 to 15 μm from the viewpoint of improving the gas diffusibility of the catalyst layer 12 and improving the power generation characteristics of the polymer electrolyte fuel cell. Moreover, it is preferable that the thickness of the catalyst layer 12 is uniform. If the thickness of the catalyst layer 12 is reduced, the amount of the electrode catalyst per unit area may be reduced and the reaction activity of the electrode may be lowered. In this case, platinum or a platinum alloy is highly supported as the electrode catalyst. By using the supported catalyst supported at a high rate, the reaction activity of the electrode can be maintained high without a shortage of the amount of the electrode catalyst.

(Gas diffusion layer)
The gas diffusion layer 14 has a gas diffusing base material.
The gas diffusing substrate is a porous substrate having conductivity. Examples of the gas diffusing substrate include carbon cloth, carbon paper, carbon felt and the like.
The gas diffusing substrate is preferably water-repellent treated with polytetrafluoroethylene (hereinafter referred to as PTFE); a mixture of PTFE and carbon black or the like. By performing the water repellent treatment, clogging of the pores of the gas diffusing substrate due to water or the like generated in the catalyst layer 12 on the cathode side is suppressed, so that a decrease in gas diffusivity is suppressed. In addition, by using carbon black during the water repellent treatment, the conductivity of the membrane electrode assembly 10 is improved.
The thickness of the gas diffusion layer 14 is preferably 100 to 400 μm, and more preferably 140 to 350 μm.

(Electrolyte membrane)
The polymer electrolyte membrane 40 is made of an ion exchange resin membrane.
Examples of the ion exchange resin of the membrane include the same ion exchange resin as that of the catalyst layer 12, and the same ion exchange resin as that of the catalyst layer 12 is preferable.
The polymer electrolyte membrane 40 preferably contains an inhibitor that suppresses the generation of peroxide. When the polymer electrolyte fuel cell is operated for a long time, the polymer electrolyte membrane 40 deteriorates due to the generation of peroxide, and the output voltage of the polymer electrolyte fuel cell decreases. The inhibitor is preferably contained in an electrolyte membrane coating solution described later.

  The thickness of the polymer electrolyte membrane 40 is preferably 50 μm or less, more preferably 3 to 40 μm, and particularly preferably 5 to 30 μm. When the thickness of the polymer electrolyte membrane 40 is 50 μm or less, the polymer electrolyte membrane 40 is unlikely to be in a dry state, and a decrease in power generation characteristics of the solid polymer fuel cell can be suppressed. If the thickness of the polymer electrolyte membrane 40 is 3 μm or more, a short circuit hardly occurs.

As the method for producing the polymer electrolyte membrane 40, when the ion exchange resin is a copolymer H, the following method (x) or method (y) may be mentioned. From the viewpoint of thickness accuracy and productivity, the method ( y) is preferred.
(X) A method of converting the —SO ₂ F group into a sulfonic acid group after the precursor polymer F is formed into a film.
(Y) A method of forming the copolymer H into a film.

Method (x):
Examples of the method for forming the precursor polymer F into a film include an extrusion molding method, a pressure press molding method, and a stretching method.
Conversion of the —SO ₂ F group into a sulfonic acid group is performed by hydrolysis and acidification treatment.

Method (y):
Examples of a method for forming the copolymer H into a film include a method (cast method) in which an electrolyte membrane coating solution containing the copolymer H is coated on a substrate film and dried.
The electrolyte membrane coating solution is a dispersion in which the copolymer H is dispersed in a dispersion medium containing alcohol and water.

The drying temperature is preferably 70 to 170 ° C.
After drying or simultaneously with drying, the polymer electrolyte membrane 40 is heat-treated (annealed).
The heat treatment temperature is preferably from 100 to 250 ° C, more preferably from 130 to 220 ° C, particularly preferably above the glass transition temperature (Tg) of the copolymer H and not more than (Tg + 100) ° C.
The heat treatment time is preferably 5 minutes to 3 hours, and more preferably 10 minutes to 1 hour. If the heat treatment time is 5 minutes or more, the strength of the polymer electrolyte membrane 40 is sufficient. If the heat treatment time is 3 hours or less, the productivity will be good.

(Method for producing membrane electrode assembly)
As a manufacturing method of the membrane electrode assembly 10, the following method (I) or method (II) may be mentioned.

(Method (I))
Method (I) is a method having the following steps (a) to (g).
(A) The process of forming the coating liquid layer 16 by applying the coating liquid for catalyst layers containing an electrode catalyst and an ion exchange resin on the base film 50 as shown in FIG.
(B) As shown in FIG. 2, after covering the gas diffusion layer 14 on the coating liquid layer 16 formed in the step (a), the coating liquid layer 16 is dried to form the catalyst layer 12. Process.
(C) The process of obtaining the 1st electrode 20 by peeling the base film 50 from the catalyst layer 12 formed at the process (b) as shown in FIG.
(D) The process of forming the coating liquid layer 16 by applying the coating liquid for catalyst layers containing an electrode catalyst and an ion exchange resin on the base film 50, as shown in FIG.
(E) As shown in FIG. 2, the gas diffusion layer 14 is placed on the coating liquid layer 16 formed in the step (d), and then the coating liquid layer 16 is dried to form the catalyst layer 12. Process.
(F) As shown in FIG. 2, the process of peeling the base film 50 from the catalyst layer 12 formed at the process (e), and obtaining the 2nd electrode 30.
(G) The first electrode 20 obtained in the step (c), the second electrode 30 obtained in the step (f), the polymer electrolyte membrane 40, the catalyst layers 12 and the polymer electrolyte membrane. The process of heat-bonding so that 40 may contact.

Step (a):
Examples of the base film 50 include a resin film. Examples of the material for the resin film include the following resins. From the viewpoint of heat resistance, chemical stability, and releasability, fluorine-containing resins are preferable.
Non-fluorinated resin: polyethylene terephthalate, polyethylene, polypropylene, polyimide, etc.
Fluorine-containing resin: PTFE, ethylene-TFE copolymer (hereinafter referred to as ETFE), ethylene-hexafluoropropylene copolymer, TFE-perfluoro (alkyl vinyl ether) copolymer, polyvinylidene fluoride, and the like.

The coating fluid for the catalyst layer is prepared by dispersing the electrode catalyst in a solvent and dissolving or dispersing the ion exchange resin in the solvent.
When the ion exchange resin is a fluorine-containing ion exchange resin, the solvent is preferably an alcohol or a fluorine-containing solvent.
Examples of alcohols include ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and tert-butanol. In order to increase the solubility of the ion exchange resin, a mixed solvent of alcohols and water may be used.

The following are mentioned as a fluorine-containing solvent.
Hydrofluorocarbon: 2H-perfluoropropane, 1H, 4H-perfluorobutane, 2H, 3H-perfluoropentane, 3H, 4H-perfluoro (2-methylpentane), 2H, 5H-perfluorohexane, 3H-perfluoro (2-methylpentane) and the like.
Fluorocarbon: perfluoro (1,2-dimethylcyclobutane), perfluorooctane, perfluoroheptane, perfluorohexane and the like.
Hydrochlorofluorocarbon: 1,1-dichloro-1-fluoroethane, 1,1,1-trifluoro-2,2-dichloroethane, 3,3-dichloro-1,1,1,2,2-pentafluoropropane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane and the like.
Fluoroether: 1H, 4H, 4H-perfluoro (3-oxapentane), 3-methoxy-1,1,1,2,3,3-hexafluoropropane and the like.
Fluorine-containing alcohol: 2,2,2-trifluoroethanol, 2,2,3,3,3-pentafluoro-1-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, etc. .

  When the ion exchange resin is a non-fluorine ion exchange resin, N, N-dimethylformamide, dimethyl sulfoxide, dimethylacetamide, N-methylpyrrolidone, methylene chloride, chloroform, carbon tetrachloride, 1,1,1- Examples include trichloroethane, 1,1,2-trichloroethane, trichloroethylene, and tetrachloroethylene.

  5-25 mass% is preferable and, as for the solid content concentration of the coating liquid for catalyst layers, 8-15 mass% is more preferable. If the solid content concentration of the coating liquid for the catalyst layer is 5% by mass or more, the catalyst layer coating liquid enters the gas diffusion layer 14 when the gas diffusion layer 14 is placed on the coating liquid layer 16. Less is. If the solid content concentration of the coating liquid for the catalyst layer is 25% by mass or less, the catalyst layer 12 having a uniform thickness can be formed. When the solid content concentration of the coating liquid for the catalyst layer is 8 to 15% by mass, the stability of the coating liquid for the catalyst layer is improved.

  When the shear rate is 1 (1 / S), the viscosity of the catalyst layer coating solution is preferably 200 to 8000 mPa · s, and more preferably 1000 to 4000 mPa · s. When the viscosity of the catalyst layer coating liquid is 200 mPa · s or more, the catalyst layer coating liquid hardly enters the gas diffusion layer 14. If the viscosity of the catalyst layer coating solution is 8000 mPa · s or less, the catalyst layer 12 having a uniform thickness can be formed. When the viscosity of the catalyst layer coating solution is 1000 to 4000 mPa · s, the stability of the catalyst layer coating solution is improved.

0.2-2.5 are preferable and, as for F / C in the coating liquid for catalyst layers, 0.7-2.0 are more preferable. If F / C is 0.2 or more, the catalyst layer 12 is difficult to break. If F / C is 2.5 or less, the catalyst layer 12 does not have a dense structure, and gas diffusibility is good. If F / C is 0.7 to 2.0, the catalyst layer 12 is more difficult to break and the gas diffusibility is also improved.
The coating liquid layer 16 may be a single layer or a plurality of layers. In the case of a plurality of layers, a plurality of catalyst layer coating solutions corresponding to the number of layers are prepared and applied simultaneously or sequentially. In the case of a plurality of layers, it is preferable that the F / C of each catalyst layer coating solution is gradually increased as it approaches the polymer electrolyte membrane 40.

Examples of the coating method include a batch coating method and a continuous coating method.
Examples of the batch coating method include a bar coater method, a spin coater method, and a screen printing method.
Examples of the continuous coating method include a post-measuring method or a pre-measuring method. The post-measuring method is a method in which an excess catalyst layer coating solution is applied, and the catalyst layer coating solution is subsequently removed so as to have a predetermined thickness. The pre-weighing method is a method of applying a catalyst layer coating liquid in an amount necessary to obtain a predetermined thickness.

Examples of the post-measuring method include an air doctor coater method, a blade coater method, a rod coater method, a knife coater method, a squeeze coater method, an impregnation coater method, and a comma coater method.
Examples of pre-measuring methods include die coater method, reverse roll coater method, transfer roll coater method, gravure coater method, kiss roll coater method, cast coater method, spray coater method, curtain coater method, calendar coater method, extrusion coater method, etc. It is done.
As the coating method, the screen printing method or the die coater method is preferable from the viewpoint that the coating liquid layer 16 having a uniform thickness can be formed, and the die coater method is more preferable from the viewpoint of production efficiency.

Step (b):
As the gas diffusion layer 14, the gas diffusing substrate can be used as it is. If necessary, the gas diffusing substrate may be subjected to a water repellent treatment.
The coating liquid layer 16 is a coating film that is formed by applying the catalyst layer coating liquid and in which all or part of the solvent contained in the catalyst layer coating liquid remains. The solvent remaining in the coating liquid layer 16 is preferably 20% by mass or more with respect to the solvent (100% by mass) contained in the catalyst layer coating liquid.

The gas diffusion layer 14 may be placed on the coating liquid layer 16 immediately after the catalyst layer coating liquid is applied on the base film 50, or a part of the solvent contained in the coating liquid layer 16. It may be after evaporating. Usually, since water or alcohol is used as a solvent, the gas diffusion layer 14 is placed on the coating liquid layer 16 for 5 minutes after the catalyst layer coating liquid is applied on the base film 50. Is preferred.
A part of the solvent contained in the coating liquid layer 16 may be evaporated at room temperature, or may be evaporated by heating. Before covering the gas diffusion layer 14 on the coating liquid layer 16, the heating temperature for evaporating a part of the solvent contained in the coating liquid layer 16 is preferably 100 ° C. or less.

  After covering the gas diffusion layer 14 on the coating liquid layer 16, the drying temperature when drying the coating liquid layer 16 is preferably 50 to 150 ° C. When the drying temperature is 50 ° C. or higher, drying does not take time, and the ion exchange resin of the catalyst layer 12 is sufficiently heat-treated and stabilized. When the drying temperature is 150 ° C. or lower, the catalyst layer 12 is hardly deteriorated and the catalyst layer 12 does not burn.

  When drying the coating liquid layer 16 in a continuous drying furnace, the drying temperature is preferably gradually increased, the drying time is short, and the ion exchange resin of the catalyst layer 12 is sufficiently heat-treated to provide a stable structure. It is more preferable that the drying furnace inlet temperature is 50 to 80 ° C. and the drying furnace outlet temperature is 120 to 150 ° C. from the viewpoint of improving the power generation characteristics of the polymer electrolyte fuel cell.

  After covering the gas diffusion layer 14 on the coating liquid layer 16, the drying time when drying the coating liquid layer 16 is preferably 3 to 30 minutes, and more preferably 5 to 15 minutes. If the drying time is 3 minutes or more, the drying is sufficiently performed and the solvent hardly remains. When the drying time is 30 minutes or less, the productivity is improved, and the deterioration of the catalyst layer 12 is unlikely to proceed even under a high temperature condition where the drying temperature is higher than 130 ° C. If the drying time is 5 to 15 minutes, the power generation characteristics of the polymer electrolyte fuel cell are sufficiently exhibited.

Step (c):
The step (c) may be performed immediately before the step (g), and the first electrode 20 with the base film 50 obtained in the step (b) is the base film 50 until just before the step (g). It may be stored in a protected state.

Step (d) to Step (f):
Step (d) to step (f) may be performed in the same manner as step (a) to step (c).

Step (g):
During the heat bonding, the first electrode 20, the second electrode 30, and the polymer electrolyte membrane 40 may be heat bonded at the same time, and one of the first electrode 20 and the second electrode 30 may be bonded. After the electrodes and the polymer electrolyte membrane 40 are heat bonded, the remaining electrodes and the polymer electrolyte membrane 40 may be heat bonded.
Examples of the bonding method include a hot press method, a hot roll press, ultrasonic fusion, and the like, and the hot press method is preferable from the viewpoint of in-plane uniformity.

  120-160 degreeC is preferable and, as for press temperature (temperature of the press plate in a press), 130-150 degreeC is more preferable. If the pressing temperature is 120 ° C. or higher, bonding is sufficiently performed, and an increase in resistance due to poor contact is suppressed. When the pressing temperature is 160 ° C. or lower, the catalyst layer 12 is hardly deteriorated and the polymer electrolyte membrane 40 is not easily deformed. When the pressing temperature is 130 to 150 ° C., the power generation characteristics and durability of the polymer electrolyte fuel cell are good.

  The pressing pressure is preferably 0.5 to 5 MPa, more preferably 1 to 4 MPa. When the pressing pressure is 0.5 MPa or more, the bonding is sufficiently performed, and an increase in resistance due to poor contact is suppressed. If the pressing pressure is 5 MPa or less, the catalyst layer 12 is hardly deteriorated and the polymer electrolyte membrane 40 is not easily deformed. When the pressing pressure is 1 to 4 MPa, the power generation characteristics and durability of the polymer electrolyte fuel cell are good.

  The pressing time is preferably 0.5 to 10 minutes, and more preferably 1 to 5 minutes. If the pressing time is 0.5 minutes or more, the bonding is sufficiently performed and the increase in resistance due to poor contact is suppressed. If the pressing time is 10 minutes or less, the catalyst layer 12 is not easily deteriorated, and the polymer electrolyte membrane 40 is not easily deformed. If the pressing time is 1 to 5 minutes, the power generation characteristics and durability of the polymer electrolyte fuel cell will be good.

(Method (II))
Method (II) is a method having the following step (a) to step (c), step (d ″), step (e ″) and step (g).
(A) The process of forming the coating liquid layer 16 by applying the coating liquid for catalyst layers containing an electrode catalyst and an ion exchange resin on the base film 50 as shown in FIG.
(B) As shown in FIG. 2, after covering the gas diffusion layer 14 on the coating liquid layer 16 formed in the step (a), the coating liquid layer 16 is dried to form the catalyst layer 12. Process.
(C) The process of obtaining the 1st electrode 20 by peeling the base film 50 from the catalyst layer 12 formed at the process (b) as shown in FIG.
(D ″) A step of forming a coating liquid layer 16 by applying a coating liquid for a catalyst layer containing an electrode catalyst and an ion exchange resin on the gas diffusion layer 14 as shown in FIG.
(E ″) A step of drying the coating liquid layer 16 formed in the step (d ″) to form the catalyst layer 12 and obtaining the second electrode 30 as shown in FIG.
(G) The first electrode 20 obtained in the step (c), the second electrode 30 obtained in the step (e ″), the polymer electrolyte membrane 40, the catalyst layers 12 and the polymer electrolyte. A process of heat bonding so that the film 40 comes into contact.

Step (a) to step (c):
Step (a) to step (c) may be performed in the same manner as step (a) to step (c) in method (I).

Step (d ″):
As the gas diffusion layer 14, the gas diffusing substrate can be used as it is. If necessary, the gas diffusing substrate may be subjected to a water repellent treatment.
The material, composition, preparation method and the like of the catalyst layer coating solution are the same as in step (a).
The coating method, coating conditions, etc. of the coating fluid for the catalyst layer are the same as in step (a).

Step (e "):
The drying conditions and the like of the coating liquid layer 16 are the same as in step (b).

Step (g):
Step (g) may be performed in the same manner as in step (g) in method (I).

  According to the manufacturing method of the membrane electrode assembly 10 described above, after at least one catalyst layer 12 is coated on the base film 50 with the catalyst layer coating liquid to form the coating liquid layer 16. The coating liquid layer 16 is covered with the gas diffusion layer 14 in a state where the coating liquid layer 16 contains a solvent without completely drying the coating liquid layer 16, and the coating liquid is applied in this state. Since the layer 16 is formed by drying, a part of the coating liquid layer 16 penetrates into the gas diffusion layer 14, improving the adhesion between the resulting catalyst layer 12 and the gas diffusion layer 14, and the catalyst. A large amount of ion exchange resin is present on the surface side of the layer 12. Therefore, the adhesive force at the interface between the catalyst layer 12 and the polymer electrolyte membrane 40 by heat bonding is increased, the resistance at the interface is decreased, and the power generation characteristics of the solid polymer fuel cell are improved. Further, even when the humidity is changed, peeling does not occur due to the high adhesive force at the interface, and thus the output voltage of the polymer electrolyte fuel cell does not decrease. Excellent.

[Second Embodiment]
FIG. 4 is a cross-sectional view showing another example of the membrane electrode assembly. The membrane electrode assembly 60 includes a first electrode 22 having the release layer 18, the catalyst layer 12 and the gas diffusion layer 14 in this order, and a second electrode 32 having the release layer 18, the catalyst layer 12 and the gas diffusion layer 14 in order. A polymer electrolyte membrane 40 is provided between the first electrode 22 and the second electrode 32 so as to be in contact with each release layer 18.

The first electrode 22 may be an anode or a cathode. The second electrode 32 is a cathode when the first electrode 22 is an anode, and is an anode when the first electrode 22 is a cathode.
In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in FIG.

(Peeling layer)
The release layer 18 is for improving the peelability of the base film from the electrode when forming the electrode.
As a material of the release layer 18, a material having high peelability such as silicone resin, fluorine resin, and surfactant can be used. However, in order to join the polymer electrolyte membrane in a subsequent step, the release layer 18 preferably includes an ion exchange resin, and particularly preferably includes a fluorine-based ion exchange resin as a main component. When the ion exchange resin is mainly contained, the adhesive force at the interface between the electrode and the polymer electrolyte membrane 40 can be improved when bonded to the polymer electrolyte membrane.
Examples of the ion exchange resin include those similar to the ion exchange resin of the catalyst layer 12, and the ion exchange resin that is the same as the ion exchange resin of the catalyst layer 12 and the polymer electrolyte membrane 40 is particularly preferable.
A part of the release layer 18 may enter the pores of the catalyst layer 12.

  When the release layer 18 does not contain an ion exchange resin as a main component, the thickness is preferably as thin as possible, preferably 0.3 μm or less. When the ion exchange resin is mainly contained, the thickness of the release layer 18 is preferably 0.1 to 5 μm, particularly preferably 0.5 to 3 μm. If the thickness of the release layer 18 is 0.1 μm or more, the catalyst layer 12 is not easily broken when the base film is peeled off from the electrode, and the catalyst layer 12 does not remain on the base film. When the thickness of the release layer 18 is 5 μm or less, an increase in the distance between the two catalyst layers 12 can be suppressed when the polymer electrolyte membrane 40 is joined, and an increase in resistance can be suppressed. If the thickness of the release layer 18 is 0.5 to 3 μm, the peelability of the base film from the electrode is good, sufficient adhesion with the polymer electrolyte membrane 40 can be secured, and the increase in resistance is slight. is there.

When the release layer 18 includes an ion exchange resin, the release layer 18 is obtained by coating and drying a release layer coating liquid containing the ion exchange resin on the base film.
1-10 mass% is preferable and, as for solid content concentration of the coating liquid for peeling layers, 3-8 mass% is more preferable.
The drying temperature is preferably 70 to 170 ° C.

(Method for producing membrane electrode assembly)
As a manufacturing method of the membrane electrode assembly 60, the following method (III) may be mentioned.

(Method (III))
Method (III) is a method having the following step (a ′), step (b), step (c), step (d ′), step (e) to step (g).
(A ′) As shown in FIG. 5, a coating solution for a catalyst layer containing an electrode catalyst and an ion exchange resin is applied onto the release layer 18 formed on the surface of the substrate film 50 to apply the coating solution. Forming the layer 16;
(B) As shown in FIG. 5, after covering the gas diffusion layer 14 on the coating liquid layer 16 formed in the step (a ′), the coating liquid layer 16 is dried to form the catalyst layer 12. Forming step.
(C) As shown in FIG. 5, the process of peeling the base film 50 from the peeling layer 18 and obtaining the 1st electrode 22 after a process (b).
(D ′) As shown in FIG. 5, a coating solution for a catalyst layer containing an electrode catalyst and an ion exchange resin is applied onto the release layer 18 formed on the surface of the substrate film 50 to apply the coating solution. Forming the layer 16;
(E) As shown in FIG. 5, after covering the gas diffusion layer 14 on the coating liquid layer 16 formed in the step (d ′), the coating liquid layer 16 is dried to form the catalyst layer 12. Forming step.
(F) As shown in FIG. 5, the process of peeling the base film 50 from the peeling layer 18 and obtaining the 2nd electrode 32 after a process (e).
(G) The first electrode 22 obtained in the step (c), the second electrode 32 obtained in the step (f), the polymer electrolyte membrane 40, the release layer 18 and the polymer electrolyte membrane. The process of heat-bonding so that 40 may contact.

Step (a):
The material, composition, preparation method and the like of the coating liquid for the catalyst layer are the same as in step (a) in method (I).
The coating method, coating conditions, etc. of the coating liquid for the catalyst layer are the same as in step (a) in method (I).

Step (b) to step (c):
Step (b) to step (c) may be performed in the same manner as step (b) to step (c) in method (I).

Step (d ′) to Step (f):
Step (d ′) to step (f) may be performed in the same manner as step (a ′) to step (c).

Step (g):
Step (g) may be performed in the same manner as in step (g) in method (I).

  According to the method for manufacturing the membrane electrode assembly 60 described above, the release layer 18 can peel the catalyst layer 12 from the base film 50 without breaking. In particular, when the release layer 18 contains an ion exchange resin, the release layer 18 containing more ion exchange resin than the catalyst layer 12 is provided on the surface of the catalyst layer 12 of each electrode. The adhesive force at the interface between the layer 18 and the polymer electrolyte membrane 40 is increased, the resistance at the interface is decreased, and the power generation characteristics of the polymer electrolyte fuel cell are improved. Further, even when the humidity is changed, peeling does not occur due to the high adhesive force at the interface, and thus the output voltage of the polymer electrolyte fuel cell does not decrease. Excellent.

  Moreover, after coating the coating liquid for catalyst layers on the peeling layer 18 formed in the surface of the base film 50, and forming the coating liquid layer 16, drying the coating liquid layer 16 completely. In the state where the coating liquid layer 16 contains a solvent, the gas diffusion layer 14 is placed on the coating liquid layer 16, and the coating liquid layer 16 is dried in this state to form the catalyst layer 12. Therefore, a large amount of ion exchange resin is present on the surface side of the catalyst layer 12. Therefore, the adhesive force at the interface between the release layer 18 and the catalyst layer 12 is also increased, the resistance at the interface is decreased, and the power generation characteristics of the polymer electrolyte fuel cell are improved. Further, even when the humidity is changed, peeling does not occur due to the high adhesive force at the interface, and thus the output voltage of the polymer electrolyte fuel cell does not decrease. Excellent.

[Third Embodiment]
FIG. 6 is a cross-sectional view showing another example of the membrane electrode assembly. The membrane electrode assembly 70 includes a first electrode 22 having a release layer 18, a catalyst layer 12, and a gas diffusion layer 14, a second electrode 30 having a catalyst layer 12 and a gas diffusion layer 14, and a first electrode. And a polymer electrolyte membrane 40 interposed between the release layer 18 of the first electrode 22 and the catalyst layer 12 of the second electrode 30 between the second electrode 30 and the second electrode 30.

The first electrode 22 may be an anode or a cathode. The second electrode 30 is a cathode when the first electrode 22 is an anode, and is an anode when the first electrode 22 is a cathode.
In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in FIG. The same components as those of the second embodiment are denoted by the same reference numerals as those in FIG.

(Method for producing membrane electrode assembly)
As a manufacturing method of the membrane electrode assembly 70, the following method (IV) or method (V) may be mentioned.

(Method (IV))
Method (IV) is a method having the following step (a ′), step (b), step (c), step (d ″), step (e ″) and step (g).
(A ′) As shown in FIG. 5, a coating solution for a catalyst layer containing an electrode catalyst and an ion exchange resin is applied onto the release layer 18 formed on the surface of the substrate film 50 to apply the coating solution. Forming the layer 16;
(B) As shown in FIG. 5, after covering the gas diffusion layer 14 on the coating liquid layer 16 formed in the step (a ′), the coating liquid layer 16 is dried to form the catalyst layer 12. Forming step.
(C) As shown in FIG. 5, the process of peeling the base film 50 from the peeling layer 18 and obtaining the 1st electrode 22 after a process (b).
(D ″) A step of forming a coating liquid layer 16 by applying a coating liquid for a catalyst layer containing an electrode catalyst and an ion exchange resin on the gas diffusion layer 14 as shown in FIG.
(E ″) A step of drying the coating liquid layer 16 formed in the step (d ″) to form the catalyst layer 12 and obtaining the second electrode 30 as shown in FIG.
(G) The first electrode 22 obtained in the step (c), the second electrode 30 obtained in the step (e ″), and the polymer electrolyte membrane 40 are separated from the release layer of the first electrode 22. A step of heat-bonding so that the catalyst layer 12 of the second electrode 30 and the polymer electrolyte membrane 40 are in contact with each other.

Step (a ′), step (b), step (c):
Step (a ′), step (b), and step (c) may be performed in the same manner as step (a ′), step (b), and step (c) in method (III).

Step (d ″) to Step (e ″):
The step (d ″) to the step (e ″) may be performed in the same manner as the step (d ″) to the step (e ″) in the method (II).

Step (g):
Step (g) may be performed in the same manner as in step (g) in method (III).

(Method (V))
The method (V) is a method having the following step (a ′) and step (b) to step (g).
(A ′) As shown in FIG. 5, a coating solution for a catalyst layer containing an electrode catalyst and an ion exchange resin is applied onto the release layer 18 formed on the surface of the substrate film 50 to apply the coating solution. Forming the layer 16;
(B) As shown in FIG. 5, after covering the gas diffusion layer 14 on the coating liquid layer 16 formed in the step (a ′), the coating liquid layer 16 is dried to form the catalyst layer 12. Forming step.
(C) As shown in FIG. 5, the process of peeling the base film 50 from the peeling layer 18 and obtaining the 1st electrode 22 after a process (b).
(D) The process of forming the coating liquid layer 16 by applying the coating liquid for catalyst layers containing an electrode catalyst and an ion exchange resin on the base film 50, as shown in FIG.
(E) As shown in FIG. 2, the gas diffusion layer 14 is placed on the coating liquid layer 16 formed in the step (d), and then the coating liquid layer 16 is dried to form the catalyst layer 12. Process.
(F) As shown in FIG. 2, the process of peeling the base film 50 from the catalyst layer 12 formed at the process (e), and obtaining the 2nd electrode 30.
(G) The first electrode 22 obtained in the step (c), the second electrode 30 obtained in the step (f), and the polymer electrolyte membrane 40 are combined with the release layer 18 of the first electrode 22. Heating and joining so that the polymer electrolyte membrane 40 and the catalyst layer 12 of the second electrode 30 and the polymer electrolyte membrane 40 are in contact with each other.

Step (a ′), step (b), step (c):
Step (a ′), step (b), and step (c) may be performed in the same manner as step (a ′), step (b), and step (c) in method (III).

Step (d) to Step (f):
Step (d) to step (f) may be performed in the same manner as step (d) to step (f) in method (I).

Step (g):
Step (g) may be performed in the same manner as in step (g) in method (III).

  According to the manufacturing method of the membrane electrode assembly 70 described above, the release layer 18 can peel the catalyst layer 12 from the base film 50 without breaking. In particular, when the release layer 18 contains an ion exchange resin, the release layer 18 containing more ion exchange resin than the catalyst layer 12 is provided on the surface of the catalyst layer 12 of the first electrode 22. The adhesive force at the interface between the release layer 18 and the polymer electrolyte membrane 40 due to bonding is increased, the resistance at the interface is decreased, and the power generation characteristics of the polymer electrolyte fuel cell are improved. Further, even when the humidity is changed, peeling does not occur due to the high adhesive force at the interface, and thus the output voltage of the polymer electrolyte fuel cell does not decrease. Excellent.

  Moreover, after coating the coating liquid for catalyst layers on the peeling layer 18 formed in the surface of the base film 50, and forming the coating liquid layer 16, drying the coating liquid layer 16 completely. In the state where the coating liquid layer 16 contains a solvent, the gas diffusion layer 14 is placed on the coating liquid layer 16, and the coating liquid layer 16 is dried in this state to form the catalyst layer 12. Therefore, a large amount of ion exchange resin is present on the surface side of the catalyst layer 12. Therefore, the adhesive force at the interface between the release layer 18 and the catalyst layer 12 is also increased, the resistance at the interface is decreased, and the power generation characteristics of the polymer electrolyte fuel cell are improved. Further, even when the humidity is changed, peeling does not occur due to the high adhesive force at the interface, and thus the output voltage of the polymer electrolyte fuel cell does not decrease. Excellent.

[Solid polymer fuel cell]
A polymer electrolyte fuel cell can be obtained by disposing separators in which grooves serving as gas flow paths are formed on both surfaces of the membrane electrode assembly obtained by the production method of the present invention.
Examples of the separator include a separator made of various conductive materials such as a metal separator, a carbon separator, and a separator made of a material in which graphite and a resin are mixed.
In the polymer electrolyte fuel cell, power is generated by supplying a gas containing oxygen to the cathode and a gas containing hydrogen to the anode. The membrane electrode assembly obtained by the production method of the present invention can also be applied to a methanol fuel cell in which methanol is supplied to the anode to generate power.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.
Examples 1 and 2 are reference examples, Example 3 is an example, and Example 4 is a comparative example.

(Copolymer H)
A copolymer H1 (ion exchange capacity 1.1 meq / g dry resin) composed of units based on TFE and repeating units represented by the following formula (1-1) was prepared.

(Polymer electrolyte membrane)
Copolymer H1 was dispersed in a mixed solvent of ethanol and water (ethanol / water = 60/40 (mass ratio)) to prepare an electrolyte membrane coating solution having a solid content concentration of 25 mass%.
On the ETFE film (base film), an electrolyte membrane coating solution is applied using a die coater so that the dry film thickness is 25 μm, dried in a 90 ° C. drier for 10 minutes, and further 140 ° C. For 30 minutes. The ETFE film was peeled off to obtain a polymer electrolyte membrane (A).

(Gas diffusion layer)
As a gas diffusive substrate constituting the gas diffusion layer, carbon paper whose surface is water repellent treated with a dispersion containing carbon black particles and polytetrafluoroethylene (product name: H2315T10AC1 manufactured by NOK) (hereinafter referred to as carbon) Paper (B).) Was prepared.

(Anode catalyst layer coating solution)
Copolymer H1 was dispersed in ethanol to prepare a copolymer dispersion having a solid concentration of 10% by mass.
A catalyst (made by Tanaka Kikinzoku Kogyo Co., Ltd., trade name: TEC61E54, platinum / ruthenium alloy supported) on which a platinum / ruthenium alloy (platinum / ruthenium = 31/22 (mass ratio)) is supported on a carbon support (specific surface area 800 m ² / g). 33 g of an amount: 53% by mass) is added to 227.5 g of distilled water, pulverized using an ultrasonic wave application device, 117.5 g of ethanol is further added, and the mixture is stirred well to obtain an electrode catalyst dispersion. Prepared.
To the electrode catalyst dispersion, 122.5 g of the copolymer dispersion was added and stirred well to prepare an anode catalyst layer coating solution (C).

(Cathode catalyst layer coating solution)
Copolymer H1 was dispersed in ethanol to prepare a copolymer dispersion having a solid concentration of 10% by mass.
35 g of a catalyst (platinum / cobalt alloy supported amount: 40% by mass) in which platinum / cobalt alloy (platinum / cobalt = 36/4 (mass ratio)) is supported on a carbon support (specific surface area 250 m ² / g) is distilled. The mixture was added to 226.5 g of water, pulverized using an ultrasonic wave application device, further added with 37.5 g of ethanol, and stirred well to prepare an electrode catalyst dispersion.
To the electrode catalyst dispersion, 210 g of the copolymer dispersion was added and stirred well to prepare a cathode catalyst layer coating solution (D).

(Base film with release layer formed on the surface)
Copolymer H1 was dispersed in a mixed solvent of ethanol and water (ethanol / water = 60/40 (mass ratio)) to prepare a release layer coating solution having a solid content concentration of 6 mass%.
The release layer coating solution was applied on the ETFE film using a die coater so that the dry film thickness was 2 μm, and dried in an oven at 80 ° C. for 10 minutes to form a release layer on the surface. A base film was obtained.

[Example 1]
Step (a):
On the ETFE film, the anode catalyst layer coating solution (C) was applied using a die coater so that the amount of platinum was 0.2 mg / cm ² to form a coating solution layer.

Step (b):
Immediately after forming the coating liquid layer, the carbon paper (B) was placed on the coating liquid layer, and the coating liquid layer was dried in an oven at 80 ° C. for 15 minutes to form an anode catalyst layer.

Step (c):
The ETFE film was peeled off from the anode catalyst layer to obtain an anode composed of carbon paper (B) and an anode catalyst layer.

Step (d):
On the ETFE film, the cathode catalyst layer coating solution (D) was applied using a die coater so that the amount of platinum was 0.2 mg / cm ² to form a coating solution layer.

Step (e):
Immediately after forming the coating solution layer, carbon paper (B) was placed on the coating solution layer, and the coating solution layer was dried in an oven at 80 ° C. for 15 minutes to form a cathode catalyst layer.

Step (f):
The ETFE film was peeled off from the cathode catalyst layer to obtain a cathode composed of carbon paper (B) and the cathode catalyst layer.

Step (g):
The polymer electrolyte membrane (A) is disposed between the anode and the cathode, stacked so that the catalyst layers of the respective electrodes are in contact with the polymer electrolyte membrane (A), and placed in a press machine heated to 140 ° C. in advance. A membrane electrode assembly having an electrode area of 25 cm ² was obtained by hot pressing for 1 minute at a pressing pressure of 1.5 MPa.

(Evaluation of power generation characteristics)
The membrane electrode assembly is incorporated in a power generation cell, hydrogen (utilization rate 70%) / air (utilization rate 50%) is supplied at normal pressure, and the cell temperature is 65 ° C., and the current density is 0.2 A / cm ^2. Alternatively, the cell voltage at the initial stage of operation at 1.0 A / cm ² was measured. However, hydrogen having a dew point of 65 ° C. was supplied to the anode side, and air having a dew point of 65 ° C. was supplied to the cathode side. Table 1 shows the cell voltage.

(Evaluation of humidity resistance)
The membrane electrode assembly was incorporated into a power generation cell, and nitrogen was passed through both electrodes at a pressure of 1 L / min at normal pressure. Nitrogen permeation was measured in a state where dry air and 150% humidified air flow alternately every two minutes and a differential pressure of 20 kPa was periodically applied. Table 1 shows the nitrogen permeation amount after 20000 times. There was no change compared to the initial value.

(Adhesive strength at the membrane / electrode interface)
The anode catalyst layer and the polymer electrolyte membrane (A) are placed in contact with each other, placed in a press machine preheated to 140 ° C., and hot-pressed at a pressure of 1.5 MPa for 1 minute. A membrane anode assembly in which the electrolyte membrane (A) was joined was produced. The gas diffusion layer side of the joined body was fixed, the end of the polymer electrolyte membrane (A) was sandwiched between the chucks of a tensile tester, and the 90 ° peel strength was measured under the following conditions. Table 1 shows the 90-degree peel strength.
Sample width: 25mm,
Peeling speed: 50 mm / min,
Temperature: 25 ° C.

  The cathode catalyst layer and the polymer electrolyte membrane (A) are placed in contact with each other, placed in a press machine preheated to 140 ° C., and hot-pressed for 1 minute at a press pressure of 1.5 MPa. A membrane / cathode assembly in which the electrolyte membrane (A) was joined was produced. The 90 ° peel strength of the joined body was measured in the same manner. Table 1 shows the 90-degree peel strength.

[Example 2]
Step (a) to step (c):
An anode was obtained in the same manner as in step (a) to step (c) of Example 1.

Step (d ″):
On the carbon paper (B), the cathode catalyst layer coating solution (D) was applied using a die coater so that the amount of platinum was 0.2 mg / cm ² to form a coating solution layer.

Step (e "):
The coating liquid layer was dried in an oven at 80 ° C. for 15 minutes to form a cathode catalyst layer to obtain a cathode composed of carbon paper (B) and a cathode catalyst layer.

Step (g):
In the same manner as in Step (g) of Example 1, a membrane / electrode assembly having an electrode area of 25 cm ² was obtained.

  The membrane electrode assembly is evaluated for power generation characteristics and humidity fluctuation resistance. The results are shown in Table 1. The nitrogen permeation amount after 20000 times does not change compared to the initial value.

[Example 3]
Step (a ′):
The anode catalyst layer coating solution (C) is applied onto the release layer of the base film on the surface of which the release layer is formed using a die coater so that the amount of platinum is 0.2 mg / cm ^2. A coating liquid layer was formed.

Step (b):
Immediately after forming the coating liquid layer, the carbon paper (B) was placed on the coating liquid layer, and the coating liquid layer was dried in an oven at 80 ° C. for 15 minutes to form an anode catalyst layer.

Step (c):
The ETFE film was peeled from the release layer to obtain an anode composed of carbon paper (B), an anode catalyst layer, and a release layer.

Step (d ′)
The cathode catalyst layer coating solution (D) is applied onto the release layer of the base film on the surface of which the release layer is formed using a die coater so that the amount of platinum is 0.2 mg / cm ^2. A coating liquid layer was formed.

Step (e):
Immediately after forming the coating solution layer, carbon paper (B) was placed on the coating solution layer, and the coating solution layer was dried in an oven at 80 ° C. for 15 minutes to form a cathode catalyst layer.

Step (f):
The ETFE film was peeled from the release layer to obtain a cathode composed of carbon paper (B), a cathode catalyst layer, and a release layer.

Step (g):
In the same manner as in Step (g) of Example 1, a membrane / electrode assembly having an electrode area of 25 cm ² was obtained.

The membrane electrode assembly is evaluated for power generation characteristics and humidity fluctuation resistance. The results are shown in Table 1. The nitrogen permeation amount after 20000 times does not change compared to the initial value.
Further, the 90-degree peel strength was measured in the same manner as in Example 1. The results are shown in Table 1.

[Example 4]
Step (a ″):
On the carbon paper (B), the anode catalyst layer coating solution (C) was applied using a die coater so that the amount of platinum was 0.2 mg / cm ² to form a coating solution layer.

Step (b ″):
The coating liquid layer was dried in an oven at 80 ° C. for 15 minutes to form an anode catalyst layer to obtain an anode composed of carbon paper (B) and an anode catalyst layer.

Steps (d ″) to (e ″)
In the same manner as in Steps (d ″) to (e ″) of Example 2, a cathode was obtained.

Step (g)
In the same manner as in Step (g) of Example 1, a membrane / electrode assembly having an electrode area of 25 cm ² was obtained.

The membrane electrode assembly was evaluated for power generation characteristics and resistance to variation in humidity. The results are shown in Table 1. The amount of nitrogen permeation after 20000 times markedly increased compared to the initial value.
Further, the 90-degree peel strength was measured in the same manner as in Example 1. The results are shown in Table 1.

  Since the membrane electrode assembly obtained by the production method of the present invention has a high output voltage in a wide range of current densities, it is used as a power source for mobile bodies such as automobiles, a distributed power generation system, a home cogeneration system, etc. It is extremely useful for polymer electrolyte fuel cells.

DESCRIPTION OF SYMBOLS 10 Membrane electrode assembly 12 Catalyst layer 14 Gas diffusion layer 16 Coating liquid layer 18 Release layer 20 1st electrode 22 1st electrode 30 2nd electrode 32 2nd electrode 40 Polymer electrolyte membrane 50 Base film 60 Membrane electrode assembly 70 Membrane electrode assembly

Claims (4)

A first electrode having a release layer, a catalyst layer, and a gas diffusion layer in order;
A second electrode having a catalyst layer and a gas diffusion layer;
A polymer electrolyte membrane disposed between a release layer of the first electrode and a catalyst layer of the second electrode, and a method for producing a membrane electrode assembly for a polymer electrolyte fuel cell,
The manufacturing method of the membrane electrode assembly for polymer electrolyte fuel cells which has the following process (a '), process (b), process (c), and process (g).
(A ′) A step of applying a coating liquid containing an electrode catalyst and an ion exchange resin on the release layer formed on the surface of the base film to form a coating liquid layer.
(B) A step of applying a gas diffusion layer on the coating liquid layer formed in step (a ′) and then drying the coating liquid layer to form a catalyst layer.
(C) The process of peeling a base film from the said peeling layer and obtaining the said 1st electrode after a process (b).
(G) The first electrode obtained in step (c), the second electrode, and the polymer electrolyte membrane are brought into contact with the release layer of the first electrode and the polymer electrolyte membrane. And a step of heat bonding so that the catalyst layer of the second electrode and the polymer electrolyte membrane are in contact with each other. A first electrode having a release layer, a catalyst layer, and a gas diffusion layer in order;
A second electrode having a release layer, a catalyst layer and a gas diffusion layer in order,
A polymer electrolyte membrane disposed between the release layer of the first electrode and the release layer of the second electrode, and a method for producing a membrane electrode assembly for a polymer electrolyte fuel cell,
The manufacturing method of the membrane electrode assembly for polymer electrolyte fuel cells which has the following process (a ') and process (b)-process (g).
(A ′) A step of applying a coating liquid containing an electrode catalyst and an ion exchange resin on the release layer formed on the surface of the base film to form a coating liquid layer.
(B) A step of applying a gas diffusion layer on the coating liquid layer formed in step (a ′) and then drying the coating liquid layer to form a catalyst layer.
(C) The process of peeling a base film from the said peeling layer and obtaining the said 1st electrode after a process (b).
(D ′) A step of applying a coating liquid containing an electrode catalyst and an ion exchange resin on the release layer formed on the surface of the substrate film to form a coating liquid layer.
(E) A step of applying a gas diffusion layer on the coating liquid layer formed in the step (d ′) and then drying the coating liquid layer to form a catalyst layer.
(F) After the step (e), a step of peeling the base film from the release layer to obtain the second electrode.
(G) The first electrode obtained in the step (c), the second electrode obtained in the step (f), and the polymer electrolyte membrane are in contact with the release layer and the polymer electrolyte membrane. Step of heat bonding.   The method for producing a membrane electrode assembly for a polymer electrolyte fuel cell according to claim 1 or 2, wherein the release layer contains an ion exchange resin, and the thickness of the release layer is 0.1 to 5 µm. The electrode catalyst comprises a noble metal, the amount of noble metal per unit area of the catalyst layer is 0.01 to 0.5 / cm ^2, polymer electrolyte according to claim 1 Manufacturing method of fuel cell membrane electrode assembly.

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