JP5052024B2 - Membrane-electrode assembly manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a membrane-electrode assembly of a polymer electrolyte fuel cell. More specifically, the present invention relates to a method for producing a membrane-electrode assembly having a reinforcing member at the peripheral edge of a polymer electrolyte membrane.

  A polymer electrolyte fuel cell has a structure in which catalyst layers (electrode layers) are laminated on both surfaces of a polymer electrolyte membrane having proton conductivity. This structure is called a membrane-electrode assembly (MEA: Membrane Electrode Assembly). Gas diffusion layers are provided on both surfaces of the membrane-electrode assembly to form a membrane-electrode-gas diffusion layer assembly. The membrane-electrode-gas diffusion layer assembly is hermetically sandwiched between a pair of separators engraved with gas flow paths to form a cell, and the cell is stacked to form a structure called a stack.

  An oxidant gas such as oxygen is supplied to one surface (cathode side) of the polymer electrolyte membrane via the flow path of one separator. Fuel, such as hydrogen, is supplied to the other surface (anode side) of the polymer electrolyte membrane via the flow path of the other separator. On the anode side, the fuel diffuses in the gas diffusion layer and reaches the catalyst layer, and protons and electrons are generated from the fuel by an electrode reaction in the catalyst layer. The protons pass through the polymer electrolyte membrane and move to the cathode side. On the cathode side, the oxidant diffuses in the gas diffusion layer and reaches the catalyst layer, and water and the like are generated from the proton and the oxidant by the electrode reaction. The electrode reaction on the cathode side and the anode side is promoted by a catalyst such as platinum contained in the catalyst layer. Although the electrons are also attracted to the cathode side, the energy of the chemical reaction (redox reaction) can be used as electric power by taking out the flow of the electrons to the outside.

  When manufacturing the stack, the polymer electrolyte membrane is sandwiched between electrodes and a separator, and tightened with an end plate and a bolt. The polymer electrolyte membrane needs to have sufficient strength so that it can withstand the tightening pressure and so that physical damage due to wear or the like does not occur during long-term use. On the other hand, for reasons such as improving proton conductivity, the polymer electrolyte membrane needs to be as thin as possible. For these reasons, it is desirable to increase the strength of the polymer electrolyte membrane without increasing the thickness.

As a technique for solving this problem, there is a polymer electrolyte fuel cell disclosed in Experimental Example 2 of Patent Document 1. In this polymer electrolyte fuel cell, the strength of the polymer electrolyte membrane is improved by attaching a frame to the peripheral edge of the polymer electrolyte membrane. The catalyst layer is applied on a carbon non-woven fabric (gas diffusion layer) and joined to a polymer electrolyte membrane to which a frame is attached. The carbon non-woven fabric (gas diffusion layer) and the catalyst layer are formed slightly larger (on the order of 1 mm) on both sides than the holes of the frame so that the catalyst layer completely covers the inside of the frame.
JP-A-10-308228

  In the conventional configuration, since the catalyst layer and the gas diffusion layer are larger than the holes of the frame body, the catalyst layer rides on the frame body together with the gas diffusion layer. The catalyst layer riding on the frame comes into contact with the corner of the inner edge of the frame. When the membrane-electrode assembly is sandwiched between the separators in such a state, the pressure is concentrated on the contact portion between the catalyst layer and the frame, and the catalyst layer may be distorted or damaged. Distortion and damage can be prevented by making the catalyst layer smaller than the hole in the frame. However, in such a configuration, there is a possibility that a gap is formed between the gas diffusion layer and the catalyst layer and the frame, and a short circuit of the reaction gas may occur through the gap. As described above, in the conventional method, it is difficult to manufacture a membrane-electrode assembly having no overlap or gap between the frame and the catalyst layer due to the limit of accuracy of alignment and part dimensions.

  The present invention has been made in order to solve the above-described problems, a frame (reinforcing member) is disposed on the peripheral edge of the polymer electrolyte membrane, and a catalyst layer is formed inside the reinforcing member without a gap, An object of the present invention is to provide a method for efficiently producing a membrane-electrode assembly in which a catalyst layer is not easily distorted or damaged by pressing during stack assembly.

  The inventors of the present invention have intensively studied to improve the power generation efficiency, device life, manufacturing efficiency, etc., in a fuel cell having a membrane-electrode assembly in which the periphery of the polymer electrolyte membrane is reinforced with a hard resin. As a result, it has been found that problems (cross leak, crossover) in which the reaction gas (oxidant gas, fuel gas) reacts directly through the membrane easily occur at the peripheral portion of the polymer electrolyte membrane. The cause of the problem was presumed to be that in the membrane-electrode assembly, there was a route for the reaction gas to reach the membrane directly from the gas diffusion layer without passing through the catalyst layer. The portion where the cross leak occurred was concentrated on the peripheral portion of the polymer electrolyte membrane. It has also been found that the deterioration of the membrane progresses specifically and rapidly at the peripheral portion, which may reduce the life of the fuel cell. In order to prevent cross-leakage, it is necessary to configure the membrane-electrode assembly so that the reaction gas always reaches the polymer electrolyte membrane through the catalyst layer.

  In the conventional method, as described above, an overlap or a gap is easily generated between the catalyst layer and the frame. If there is a gap, naturally a cross leak occurs. On the other hand, if the catalyst layer is configured to overlap the frame body, it is considered that no cross leak occurs because the gas passes through the catalyst layer and reaches the membrane. However, the pressure is concentrated on the overlapping portion of the frame and the catalyst layer. If the catalyst layer is distorted or damaged by the pressing, a cross leak will occur. From the above examination, the present inventors have realized that the overlap and the gap are problems that inevitably occur when the frame body and the catalyst layer are separately formed and joined. Furthermore, the present inventors have come to the idea that if a catalyst layer is applied to the inside of the frame after attaching the frame to the polymer electrolyte membrane, no overlap or gap will occur between the frame and the catalyst layer. It was.

  Some polymer electrolyte membranes expand and contract due to humidity and the like, and when a catalyst layer is applied directly to the membrane, wrinkles may be caused, which may be a problem. For these reasons as well, a method for directly forming a catalyst layer on a membrane has not been common. However, according to the study by the present inventors, while the membrane is sucked and fixed by a suction fixing device (a suction fixing device by a decompression method), or while the membrane is placed on the backing member (while being held, It was also found that wrinkle generation can be prevented by applying the catalyst layer while remaining fixed.

  In order to solve the above-described problems, a method for producing a membrane-electrode assembly according to the present invention includes a reinforcement member having a frame portion formed so as to surround an opening, and the frame portion includes at least one surface of a polymer electrolyte membrane. A reinforcing member disposing step provided on the polymer electrolyte membrane so as to cover a peripheral portion, and a catalyst layer applying step of applying a catalyst layer on the entire surface of the polymer electrolyte membrane exposed at least in the opening of the reinforcing member And a gas diffusion layer disposing step of disposing a gas diffusion layer so as to cover the catalyst layer.

  In such a method, the catalyst layer covers the entire inner surface of the opening of the reinforcing member and is applied so as to protrude from the reinforcing member, so that no gap is generated between the reinforcing member and the catalyst layer. The catalyst layer is not printed and attached to a nonwoven fabric or the like, but is applied to the polymer electrolyte membrane, so that even if the catalyst layer overlaps the reinforcing member, the catalyst layer is unlikely to be distorted or damaged. Accordingly, a membrane-electrode assembly in which a reinforcing member is disposed on the periphery of the polymer electrolyte membrane, a catalyst layer is formed without gaps inside the reinforcing member, and the catalyst layer is not easily distorted or damaged by pressing during stack assembly. Can be manufactured efficiently.

  In the method for producing a membrane-electrode assembly of the present invention, the catalyst layer may be applied by spraying in the catalyst layer application step.

  If the spray is used, the catalyst layer can be easily applied so as to cover the entire inner surface of the opening of the reinforcing member and to protrude from the reinforcing member.

  The method for producing a membrane-electrode assembly according to the present invention further includes a composite member having the reinforcing member and a covering member that has substantially the same planar shape as the reinforcing member and covers one side of the reinforcing member. A composite member forming step for forming, and a covering member removing step for removing the covering member from the reinforcing member after coating the catalyst layer, wherein the reinforcing member is covered with the covering member in the reinforcing member disposing step. The composite member is provided so as to be positioned closer to the polymer electrolyte membrane than the member, and in the catalyst layer coating step, the catalyst layer is applied so as to protrude from the opening of the composite member to the periphery of the opening. May be.

  By this method, the covering member is removed after the catalyst layer is applied, so that the main surface of the reinforcing member is not contaminated by the catalyst particles. By collecting the catalyst particles on the covering member, the utilization efficiency of the catalyst can be improved. Note that substantially the same planar shape means, for example, when either the reinforcing member or the covering member has a minute notch or a hole, or when the size of the reinforcing member and the covering member is slightly different due to manufacturing errors. In addition, those having a portion that does not overlap the reinforcing member and the covering member are included.

  In the method for manufacturing a membrane-electrode assembly of the present invention, the composite member forming step may form the composite member by bonding and punching two resin sheets.

  By this method, a composite member can be easily created. Since the covering member and the reinforcing member have the same shape, the removed covering member can be used as the reinforcing member or repeatedly used as the covering member.

  In the method of manufacturing a membrane-electrode assembly according to the present invention, the reinforcing member disposing step may include a first polymer having a frame formed so as to surround the opening, and the first polymer in the frame. A first reinforcing member disposing step provided on the first polymer electrolyte membrane so as to cover a peripheral portion of at least one surface of the electrolyte membrane; and a second portion in which a frame portion is formed so as to surround the opening. A second reinforcing member disposing step of providing a reinforcing member on the second polymer electrolyte membrane so that the frame portion covers a peripheral portion of at least one surface of the second polymer electrolyte membrane; And the catalyst layer coating step includes a first catalyst layer coating for coating the first catalyst layer on the entire surface of the first polymer electrolyte membrane exposed at least in the opening of the first reinforcing member. And an entire surface of the second polymer electrolyte membrane exposed at least in the opening of the second reinforcing member And a second catalyst layer coating step for coating the second catalyst layer, and in the first polymer electrolyte membrane coated with the first catalyst layer, the first catalyst layer And a surface of the second polymer electrolyte membrane coated with the second catalyst layer that is not coated with the second catalyst layer. You may have a film | membrane contact process.

  By this method, the catalyst layer can be separately applied to the two polymer electrolyte membranes.

  In the method of manufacturing a membrane-electrode assembly according to the present invention, the first reinforcing member and the first reinforcing member have substantially the same planar shape and cover one side of the first reinforcing member. A first composite member forming step of forming a first composite member having a first covering member that has substantially the same planar shape as the second reinforcing member and the second reinforcing member; A second composite member forming step of forming a second composite member having a second covering member that covers one side of the second reinforcing member; and after applying the first catalyst layer, the first composite member A first covering member removing step of removing the covering member from the first reinforcing member; and a second step of removing the second covering member from the second reinforcing member after applying the second catalyst layer. A covering member removing step, wherein in the first reinforcing member disposing step, the first auxiliary member is disposed. The first composite member is provided so that the member is positioned closer to the first polymer electrolyte membrane than the first covering member. In the second reinforcing member disposing step, the second reinforcing member is provided. The second composite member is provided such that the member is positioned closer to the second polymer electrolyte membrane than the second covering member, and in the first catalyst layer coating step, the first composite layer is provided. The first catalyst layer is applied so as to protrude from the opening of the member to the periphery of the opening. In the second catalyst layer application step, the opening of the second composite member is extended to the periphery of the opening. The second catalyst layer may be applied so as to protrude.

  By this method, the covering member is removed after the catalyst layer is applied, so that the main surface of the reinforcing member is not contaminated by the catalyst particles. By collecting the catalyst particles on the covering member, the utilization efficiency of the catalyst can be improved. At the same time, the catalyst layers can be separately applied to the two polymer electrolyte membranes.

  The method for producing a membrane-electrode assembly according to the present invention further includes a first polymer electrolyte membrane holding step of holding the first polymer electrolyte membrane on one surface of the first backing member, A second polymer electrolyte membrane holding step for holding the second polymer electrolyte membrane on one surface of the two backing members, wherein the first reinforcing member disposing step comprises A step of providing the first composite member on the first polymer electrolyte membrane so that a reinforcing member covers a surface of the first polymer electrolyte membrane that is not held by the first backing member; In the second reinforcing member disposing step, the second composite member is attached to the second composite member so that the second reinforcing member covers a surface of the second polymer electrolyte membrane that is not held by the second backing member. A step of providing the polymer electrolyte membrane, and further comprising the polymer electrolyte A first backing member removing step of removing the first backing member from the first polymer electrolyte membrane coated with the first catalyst layer before the contact step; and the polymer electrolyte membrane contact And a second backing member removing step of removing the second backing member from the second polymer electrolyte membrane coated with the second catalyst layer before the contacting step.

  According to this method, the main surface of the reinforcing member is not contaminated by the catalyst particles by removing the covering member after applying the catalyst layer. By collecting the catalyst particles on the covering member, the utilization efficiency of the catalyst can be improved. In addition, since the catalyst layer is applied while the polymer electrolyte membrane is fixed to the backing member, wrinkles in the polymer electrolyte membrane can be reliably prevented.

  Note that “abutment” does not necessarily refer to the case where the two members are bonded together so that they are in direct contact, but the two members via some member (such as a reinforcing material or another polymer electrolyte layer). Including the case where is attached.

  The method for producing a membrane-electrode assembly of the present invention has the above-described configuration, and has the following effects. That is, a membrane-electrode assembly in which a reinforcing member is disposed on the periphery of the polymer electrolyte membrane, a catalyst layer is formed without gaps inside the reinforcing member, and the catalyst layer is less likely to be distorted or damaged by pressing during stack assembly. It is possible to provide a method for efficiently manufacturing the process.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
[Process]
1A to 1D are process diagrams schematically showing an example of the method for producing a membrane-electrode assembly according to the first embodiment of the present invention. FIG. 1A is a diagram showing a state of only a polymer electrolyte membrane. FIG. 1B is a diagram illustrating a process in which a reinforcing member is attached to the polymer electrolyte membrane. FIG. 1C is a diagram illustrating a state in which a catalyst layer is applied from above the reinforcing member to form a membrane-electrode assembly. FIG. 1-D is a diagram showing a state where a gas diffusion layer is formed on the catalyst layer to form a membrane-electrode-gas diffusion layer assembly. Hereinafter, the membrane-electrode assembly manufacturing method of the present embodiment will be described with reference to FIGS. 1-A to 1 -D. In addition, the figure is a schematic diagram for illustrating the positional relationship of each member in each process to the last, and does not limit the relative size, shape, thickness, and the like.

  In the step shown in FIG. 1-A, a polymer electrolyte membrane 102 is prepared. The polymer electrolyte membrane 102 is preferably a membrane having proton conductivity. For example, a perfluorosulfonic acid membrane is suitably used.

  In the step shown in FIG. 1B, the reinforcing members 104A and 104B are attached to both surfaces of the peripheral edge of the polymer electrolyte membrane 102 (reinforcing member disposing step). The reinforcing members 104A and 104B are formed with a frame portion so as to surround the openings 123A and 123B, and the outer periphery of the frame portion has substantially the same shape as the outer periphery of the polymer electrolyte membrane 102. The peripheral portions on both sides of the polymer electrolyte membrane 102 are covered with the frame portions of the reinforcing members 104A and 104B. The material of the reinforcing members 104A and 104B is preferably one having corrosion resistance (acid resistance) and heat resistance. For example, polytetrafluoroethylene resin (PTFE) is suitably used. The reinforcing members 104A and 104B are manufactured, for example, by punching a PTFE sheet with a Thomson type, for example. The method of attaching the reinforcing members 104A and 104B to the polymer electrolyte membrane 102 is preferably one that can be attached with an appropriate strength. For example, thermocompression bonding or adhesion using an adhesive is used.

  In the step shown in FIG. 1-C, the catalyst layers 109A and 109B (electrodes) are applied (catalyst layer application step). As the catalyst layers 109A and 109B, for example, a mixture of catalyst supporting particles in which a catalyst such as platinum is supported on carbon particles and a polymer electrolyte is preferably used. For coating the catalyst layers 109A and 109B, for example, a polymer electrolyte resin is mixed with a solvent such as alcohol or a mixture of alcohol and water to form a dispersion liquid, and catalyst-supported particles are further mixed to adjust the catalyst dispersion liquid. The catalyst dispersion is applied onto the polymer electrolyte membrane 102 and the reinforcing member 104 using a known thin film manufacturing technique such as spraying, spin coating, doctor blade, die coating, or screen printing, and dried. The catalyst layers 109A and 109B are formed by volatilizing the solvent. As a method for applying the catalyst layer, a spray method is most preferable.

  When the catalyst dispersion is applied, wrinkles may occur in the polymer electrolyte membrane. In order to prevent the generation of wrinkles, it is preferable to fix the polymer electrolyte membrane during the application of the catalyst layer. Examples of the fixing method include fixing by a suction fixing device (a suction fixing device by a decompression method) capable of fixing the polymer electrolyte membrane to the processing stage by suction and use of a backing member.

  When using a suction fixing device (vacuum fixing device), place the polymer electrolyte membrane on the processing stage of the suction fixing device (vacuum suction device) and suck one surface (surface A). In this way, the membrane is fixed, and after the reinforcing member is attached to the opposite surface (surface B), the catalyst layer is applied. After coating the catalyst layer on the surface B, remove the polymer electrolyte membrane from the processing stage of the suction fixing device (suction fixing device by decompression method), invert it and suck the surface B side to fix the polymer electrolyte membrane again Then, the reinforcing member is attached to the surface A and the catalyst layer is applied.

  When the backing member is used, first, the polymer electrolyte membrane is held on the backing member, and the reinforcing member is attached to the surface (surface B) opposite to the surface (surface A) in contact with the backing member. Apply the layer. After applying the catalyst layer to the surface B, the backing member is removed from the polymer electrolyte membrane, and the reinforcing member is attached to the surface A and the catalyst layer is applied to the surface A.

  The catalyst layer 109A is applied so as to cover the polymer electrolyte membrane 102 over the entire surface of the polymer electrolyte membrane 102 exposed to the opening 123A of the reinforcing member 104A and to protrude to the peripheral portion of the opening 123A. The catalyst layer 109B is applied so as to cover the polymer electrolyte membrane 102 over the entire surface of the polymer electrolyte membrane 102 exposed in the opening 123B of the reinforcing member 104B and to protrude from the peripheral portion of the opening 123B. The membrane-electrode assembly 113 is obtained by applying the catalyst layers 109A and 109B.

1D, gas diffusion layers 114A and 114B are formed so as to cover the catalyst layers 109A and 109B (gas diffusion layer disposing step). The gas diffusion layers 114A and 114B are preferably those having sufficient gas permeability and conductivity. For example, carbon cloth or the like is suitably used. As a method for attaching the gas diffusion layers 114A and 114B, those that can be joined with an appropriate strength are preferable. However, when sandwiched between separators or the like, the membrane-electrode assembly 113 and the gas diffusion layers 114A and 114B may be simply laminated without bonding. The gas diffusion layers 114A and 114B are preferably configured to be equal to or smaller than the catalyst layers 109A and 109B. The gas diffusion layer and the catalyst layer are not necessarily in direct contact with each other, and another layer may be provided between them. By forming the gas diffusion layers 114A and 114B, the membrane-electrode-gas diffusion layer assembly 115 is obtained.
[Construction]
FIG. 2 is a schematic view showing a cross section of the membrane-electrode-gas diffusion layer assembly produced by the membrane-electrode assembly manufacturing method according to the first embodiment of the present invention in use. As shown in FIG. 2, in use, in the membrane-electrode-gas diffusion layer assembly 115, the outer periphery of the gas diffusion layers 114A and 114B is surrounded by frame-shaped gaskets 119A and 119B. Further, the membrane-electrode-gas diffusion layer assembly 115 and the gaskets 119A, 119B are sandwiched between the inner surfaces of the gas diffusion layers 114A, 114B by the separators 120A, 120B in which the channel 122 is engraved. The According to the membrane-electrode assembly manufacturing method of the first embodiment, catalyst layers 109A and 109B are formed on the reinforcing members 104A and 104B attached to the peripheral edge of the polymer electrolyte membrane 102, respectively. . The gas diffusion layers 114A and 114B are provided on the catalyst layers 109A and 109B, respectively. A gap 121 is formed between the gas diffusion layers 114A and 114B and the gaskets 119A and 119B, but the gap 121 is not in contact with the polymer electrolyte membrane 102. With this structure, the total amount of gas supplied from the gas diffusion layers 114A and 114B passes through the catalyst layers 109A and 109B and reaches the polymer electrolyte membrane 102.
[Features and effects]
The feature of this embodiment is that reinforcing members 104A and 104B are attached on the polymer electrolyte membrane 102, and the catalyst layer 109 is coated so as to protrude from the reinforcing members 104A and 104B. According to this method, the catalyst layers 109A and 109B cover the entire surface of the polymer electrolyte membrane 102 exposed in the openings 123A and 123B, respectively, and a gap is generated between the catalyst layers 109A and 109B and the reinforcing members 104A and 104B. Nothing will happen. With this structure, gas does not reach the polymer electrolyte membrane 102 directly from the gas diffusion layers 114A and 114B (through the gaps without passing through the catalyst layers 109A and 109B). In addition, since the catalyst layer 109 is applied directly on the polymer electrolyte membrane 102, the catalyst layer 109A, 114B can run over the reinforcing members 104A, 104B, and the gas diffusion layer can be distorted or damaged. The layer will not break.

  As is clear from the above description, according to the membrane-electrode assembly manufacturing method of the first embodiment, the reinforcing member is disposed on the peripheral edge of the polymer electrolyte membrane, and the catalyst is formed without any gap inside the reinforcing member. A membrane-electrode assembly in which a layer is formed and the catalyst layer is less likely to be distorted or damaged by pressing during stack assembly can be efficiently produced.

Also, in the membrane-electrode assembly manufacturing method of the first embodiment, unlike the membrane-electrode assembly manufacturing method of the second to third embodiments described later, the polymer electrolyte membrane is directly applied so as to ride on the reinforcing member. Coated. With this configuration, a covering member is not necessary, and the number of members can be reduced.
(Second Embodiment)
[Process]
FIG. 3A to FIG. 3E are process diagrams schematically showing an example of the membrane-electrode assembly manufacturing method of the second embodiment of the present invention. FIG. 3-A is a diagram showing a state of only the polymer electrolyte membrane. FIG. 3-B is a diagram illustrating a process in which the reinforcing member and the covering member are attached to the polymer electrolyte membrane. FIG. 3C is a diagram illustrating a state in which a catalyst layer is applied from above the covering member. FIG. 3D is a diagram illustrating a state where the covering member is removed. FIG. 3E is a diagram showing a state where a gas diffusion layer is formed on the catalyst layer to form a membrane-electrode-gas diffusion layer assembly. Hereinafter, the membrane-electrode assembly manufacturing method of the present embodiment will be described with reference to FIGS. In addition, the figure is a schematic diagram for illustrating the positional relationship of each member in each process to the last, and does not limit the relative size, shape, thickness, and the like. Needless to say, the second embodiment can be modified similarly to the first embodiment.

  The membrane-electrode assembly manufacturing method of the second embodiment is 1) a point in which a composite member in which a reinforcing member and a covering member are joined is used instead of a single reinforcing member, and 2) the covering member is used as a reinforcing member after coating the catalyst layer. The method is the same as the method for manufacturing the membrane-electrode assembly according to the first embodiment except that it is removed. Therefore, the same name is attached | subjected about a common member and method, and detailed description is abbreviate | omitted.

  In the step shown in FIG. 3A, a polymer electrolyte membrane 202 is prepared.

  In the step shown in FIG. 3B, the composite member 206A composed of the reinforcing member 204A and the covering member 205A is placed on one side of the peripheral edge of the polymer electrolyte membrane 202 so that the reinforcing member 204A abuts the polymer electrolyte membrane 202. It is attached (so that the reinforcing member 204A is positioned on the polymer electrolyte membrane 202 side with respect to the covering member 205A), and is composed of the reinforcing member 204B and the covering member 205B on the other surface of the peripheral edge of the polymer electrolyte membrane 202. The composite member 206B is attached (so that the reinforcing member 206B is positioned closer to the polymer electrolyte membrane 202 than the covering member 205B) so that the reinforcing member 206B contacts the polymer electrolyte membrane 202 (reinforcing member disposing step). . The covering member 205A is made of the same material as the reinforcing member 204A, has substantially the same planar shape as the reinforcing member 204A, and covers one side of the reinforcing member 204A. The covering member 205B is made of the same material as that of the reinforcing member 204B, and has substantially the same planar shape as the reinforcing member 204B, and covers one side of the reinforcing member 204B. The reinforcing member 204A and the covering member 205A have an opening 223A. The reinforcing member 204B and the covering member 205B have an opening 223B. The reinforcing members 204A and 204B and the covering members 205A and 205B are joined so that only the covering members 205A and 205B can be removed after the catalyst layer is applied. For example, two PTFE sheets are bonded by an adhesive having a weak adhesive force. Thereafter, the composite member 206A having the opening 223A is formed by punching using, for example, a Thomson mold (composite member forming step). The composite member 206B is also formed by the same method. Note that the covering members 205A and 205B are not necessarily made of the same material as the reinforcing members 204A and 204B, and may be made of another material (such as a masking tape). For example, the covering members 205A and 205B may be configured by a frame-shaped metal plate. In such a configuration, the covering member can be reused many times in the manufacturing process, which is efficient. The reinforcing members 204A and 204B and the covering members 205A and 205B are not necessarily bonded, and the covering member may be simply placed on the reinforcing member and sprayed. Such a configuration eliminates the need for an adhesion step and facilitates removal of the covering member, thereby improving work efficiency. The shape of the covering member and that of the reinforcing member only need to match the opening, and the outer edge may not necessarily match.

  In the step shown in FIG. 3C, catalyst dispersion layers 208A and 208B (electrodes) are applied. The catalyst dispersion layer 208A covers the entire surface of the polymer electrolyte membrane 202 exposed to the opening 223A without any gap, and is further coated so as to protrude from the periphery of the opening 223A. The catalyst dispersion layer 208B is exposed to the opening 223B. The entire surface of the polymer electrolyte membrane 202 is covered without any gap, and is applied so as to protrude from the periphery of the opening 223B (catalyst layer coating step). As in the first embodiment, when wrinkles occur in the polymer electrolyte membrane when the catalyst dispersion is applied, the coating is performed while fixing the polymer electrolyte membrane with a suction fixing device (a suction fixing device using a reduced pressure method) or a backing member. It is preferable to carry out.

  In the step shown in FIG. 3D, portions where the catalyst dispersion layers 208A and 208B protrude from the peripheral portions of the openings 223A and 223B are removed together with the covering members 205A and 205B. The covering member 205A is detachably bonded to the reinforcing member 204A and easily removed from the main body portion, and the covering member 205B is also detachably bonded to the reinforcing member 204B and easily removed from the main body portion. (Coating member removing step) By this step, the catalyst layer 209A (first catalyst layer) is formed without gaps on the entire surface of the polymer electrolyte membrane 202 exposed to the opening 223A of the reinforcing member 204A, and the opening 223B of the reinforcing member 204B is formed. A catalyst layer 209B (second catalyst layer) is formed on the entire surface of the exposed polymer electrolyte membrane 202 without a gap, and a membrane-electrode assembly 213 is obtained. When the catalyst dispersion liquid is applied, the main surfaces of the reinforcing members 204A and 204B are protected by the covering members 205A and 205B, thereby preventing the main surfaces of the reinforcing members 204A and 204B from being contaminated by the catalyst particles.

In the step shown in FIG. 3E, gas diffusion layers 214A and 214B are formed on the catalyst layers 209A and 209B (gas diffusion layer disposing step). By forming the gas diffusion layers 214A and 214B, the membrane-electrode-gas diffusion layer assembly 215 is obtained. In addition, you may perform the process of FIG. 3-E before the process of FIG. 3-D.
[Construction]
FIG. 4 is a schematic diagram showing a cross-section of the membrane-electrode-gas diffusion layer assembly 215 produced by the membrane-electrode assembly manufacturing method of the second embodiment of the present invention in use. As shown in FIG. 4, in use, in the membrane-electrode-gas diffusion layer assembly 215, the outer circumferences of the gas diffusion layers 214A and 214B are surrounded by frame-shaped gaskets 219A and 219B, respectively. Further, the membrane-electrode-gas diffusion layer assembly 215 and gaskets 219A, 219B are sandwiched by separators 220A, 220B in which the channel 222 is engraved on the inner surface so that the channel 222 is in contact with the gas diffusion layers 214A, 214B. Is done. According to the membrane-electrode assembly manufacturing method of the second embodiment, the catalyst layers 209A and 209B do not protrude above the reinforcing members 204A and 204B, respectively, and there are gaps between the reinforcing members 204A and 204B, respectively. Formed without making. The gas diffusion layers 214A and 214B are provided on the catalyst layers 209A and 209B, respectively. A gap 221 is formed between the gas diffusion layers 214A and 214B and the gaskets 219A and 219B, but the gap 221 is not in contact with the polymer electrolyte membrane 202. With this structure, the total amount of gas supplied from the gas diffusion layers 214A and 214B passes through the catalyst layers 209A and 209B, respectively, and reaches the polymer electrolyte membrane 202. Since the catalyst layers 209A and 209B do not protrude above the reinforcing members 204A and 204B, the gas diffusion layers 209A and 209B and the reinforcing members 204A and 204B are in direct contact with each other.
[Features and effects]
According to the membrane-electrode assembly manufacturing method of the second embodiment, the reinforcing member is disposed on the periphery of the polymer electrolyte membrane, and the catalyst layer has no gap inside the reinforcing member, as in the first embodiment. A membrane-electrode assembly which is formed and hardly distorts or breaks the catalyst layer due to pressing during stack assembly can be efficiently produced.

Further, the second embodiment has the following features and effects. In the first embodiment, the catalyst layer protrudes from the surface of the reinforcing member. When the catalyst layer is composed of a particulate material, the catalyst layer that protrudes between the gas diffusion layer and the reinforcing member may enter, and the adhesion between the gas diffusion layer and the reinforcing member may deteriorate due to the particles of the catalyst layer. is there. Further, when a noble metal such as platinum is used as a catalyst for the catalyst layer, it is necessary to reduce the amount of catalyst particles used at the time of production as much as possible from the viewpoint of economy. If a gas diffusion layer is formed on the protruding catalyst layer, the protruding portion of the catalyst does not contribute to the reaction of the electrode and is excessively used. According to the membrane-electrode assembly manufacturing method of the present embodiment, the coating member is removed from the reinforcing member after the catalyst layer is applied from above the covering member. According to such a method, the catalyst layer does not protrude from the main surface of the reinforcing member (not contaminated by the catalyst particles), and the adhesion between the reinforcing member and the gas diffusion layer is improved. Further, at the time of stack assembly, the peripheral portion of the membrane-electrode assembly is sandwiched between the gasket and the like and is pressure-bonded. However, if the sealing performance of the peripheral portion is low, problems such as gas leakage occur. In the present embodiment, since catalyst particles do not remain on the surface of the reinforcing member, a gap is hardly generated between the reinforcing member and the gasket or the like, and the sealing performance of the peripheral portion of the membrane-electrode assembly is improved. The protruding catalyst layer can be collected and reused together with the covering member, and excessive use of the catalyst can be prevented.
(Third embodiment)
[Process]
FIG. 5-A to FIG. 5-F are process charts schematically showing an example of the membrane-electrode assembly manufacturing method of the third embodiment of the present invention. FIG. 5-A is a diagram showing a state of only the polymer electrolyte membrane. FIG. 5-B is a diagram illustrating a process in which the reinforcing member and the covering member are attached to the polymer electrolyte membrane. FIG. 5-C is a diagram showing a state in which a catalyst layer is applied from above the covering member. FIG. 5-D is a diagram illustrating a state where the covering member is removed. FIG. 5-E is a diagram showing a state in which polymer electrolyte membranes are joined to form a membrane-electrode assembly. FIG. 5-F is a diagram showing a state where a gas diffusion layer is formed on the catalyst layer to form a membrane-electrode-gas diffusion layer assembly. Hereinafter, the membrane-electrode assembly manufacturing method of the present embodiment will be described with reference to FIGS. In addition, the figure is a schematic diagram for illustrating the positional relationship of each member in each process to the last, and does not limit the relative size, shape, thickness, and the like. Needless to say, the third embodiment can be modified in the same manner as in the first and second embodiments.

  The membrane-electrode assembly manufacturing method of the third embodiment does not form reinforcing members or catalyst layers on both sides of one polymer electrolyte membrane, but on the anode side and two polymer electrolyte membranes, respectively. The method is the same as that of the membrane-electrode assembly manufacturing method of the second embodiment, except that a cathode-side reinforcing member and a catalyst layer are formed and then a polymer electrolyte membrane is bonded. Therefore, the same name is attached | subjected about a common member and method, and detailed description is abbreviate | omitted.

  In the step shown in FIG. 5-A, a polymer electrolyte membrane 302A (first polymer electrolyte membrane) and a polymer electrolyte membrane 302B (second polymer electrolyte membrane) are prepared.

  In the step shown in FIG. 5-B, a composite member 306A (first member) composed of a reinforcing member 304A (first reinforcing member) and a covering member 305A (first covering member) is formed on the peripheral edge of one surface of the polymer electrolyte membrane 302A. Are attached so that the reinforcing member 304A abuts on the polymer electrolyte membrane 302A (so that the reinforcing member 304A is positioned on the polymer electrolyte membrane 302A side with respect to the covering member 305A). Arrangement process). A composite member 306B (second composite member) composed of a reinforcing member 304B (second reinforcing member) and a covering member 305B (second covering member) is provided on the peripheral edge of one surface of the polymer electrolyte membrane 302B. Is attached to the polymer electrolyte membrane 302B (so that the reinforcing member 304B is positioned on the polymer electrolyte membrane 302B side of the covering member 305B) (second reinforcing member disposing step). The reinforcing member 304A and the covering member 305A have an opening 323A. The reinforcing member 304B and the covering member 305B have an opening 323B. The composite members 306A and 306B are created by the same method as in the second embodiment (first composite member forming step, second composite member forming step).

  In the step shown in FIG. 5C, the catalyst dispersion layer 308A (electrode) is applied so as to protrude from the opening 323A to the periphery of the opening 323A (first catalyst layer application step), and the catalyst dispersion layer 308B. (Electrode) is applied so as to protrude from the opening 323B to the periphery of the opening 323B (second catalyst layer coating step). As in the first and second embodiments, when wrinkling occurs in the polymer electrolyte membrane when the catalyst dispersion is applied, the polymer electrolyte membrane is removed with a suction fixing device (a suction fixing device using a reduced pressure system) or a backing member. It is preferable to perform coating while fixing. In this embodiment, since one polymer electrolyte membrane 302A, 302B is prepared for each of both surfaces, the composite members 306A, 306B are attached while the polymer electrolyte membranes 302A, 302B are fixed, and the catalyst layer 309A (first 309B (second catalyst layer) is preferably formed. Alternatively, the polymer electrolyte membranes 302A and 302B are held on the backing member, and the composite members 306A and 306B are attached while the polymer electrolyte membranes 302A and 302B are fixed on the backing member, and the catalyst layers 309A and 309B are attached. It may be formed.

  In the step shown in FIG. 5-D, the portion where the catalyst dispersion layer 308A protrudes from the periphery of the opening 323A of the covering member 305A is removed together with the covering member 305A (first covering member removing step). The portion where the catalyst dispersion layer 308B protrudes from the periphery of the opening 323B of the covering member 305B is removed together with the covering member 305B (second covering member removing step). By this step, the catalyst layer 309B is formed on the entire surface of the polymer electrolyte membrane 302A exposed to the opening 323A of the reinforcing member 304A without gaps, and the catalyst is formed on the entire surface of the polymer electrolyte membrane 302B exposed to the openings 304B of the reinforcing member 304B. A structure in which the layer 309B is formed is obtained.

  In the step shown in FIG. 5-E, the structure obtained in the fourth step is bonded on the side where the catalyst layer does not exist. The polymer electrolyte membrane 302A is removed from the suction fixing device (vacuum fixing device) or the backing member, and the polymer electrolyte membrane 302B is removed from the suction fixing device (vacuum suction device) or the backing member. The surfaces of the electrolyte membranes 302A and 302B that have been in contact with the suction fixing device (the suction fixing device by the decompression method) or the backing member are brought into contact with each other and bonded together (polymer electrolyte membrane contact step). A heat press is suitably used for the bonding. By hot pressing, a gas such as air that is sandwiched between the polymer electrolyte membranes 302A and 302B is easily released, and the polymer electrolyte membranes 302A and 302B are joined to form a single polymer electrolyte membrane 312. . By this step, the catalyst layer 309A (first catalyst layer) is formed on the entire surface of the polymer electrolyte membrane 312 exposed in the opening 323A of the reinforcing member 304A without any gap, and the polymer electrolyte membrane exposed in the opening 323B of the reinforcing member 304B. A membrane-electrode assembly 313 in which the catalyst layer 309B (first catalyst layer) is formed on the entire surface of 312 without a gap is obtained.

  In the step shown in FIG. 5F, gas diffusion layers 314A and 314B are disposed on the catalyst layers 309A and 309B, respectively (gas diffusion layer disposition step). By disposing the gas diffusion layers 314A and 314B, the membrane-electrode-gas diffusion layer assembly 315 is obtained.

The process of FIG. 5-D, the process of FIG. 5-E, and the process of FIG. 5-F may be performed in any order.
[Construction]
FIG. 6 is a schematic diagram showing a cross section of the membrane-electrode-gas diffusion layer assembly 315 used in the method of manufacturing the membrane-electrode assembly according to the third embodiment of the present invention in use. As shown in FIG. 6, according to the membrane-electrode assembly manufacturing method of the third embodiment, the polymer electrolyte membrane 302A and the polymer electrolyte membrane 302B are integrated into a single polymer electrolyte membrane 312. Yes. In use, in the membrane-electrode-gas diffusion layer assembly 315, the outer periphery of the gas diffusion layer 314A is surrounded by the frame-shaped gasket 319A, and the outer periphery of the gas diffusion layer 314B is surrounded by the frame-shaped gasket 319B. Further, the membrane-electrode-gas diffusion layer assembly 315 and the gaskets 319A, 319B are in contact with the gas diffusion layers 314A, 314B, respectively, by the separators 320A, 320B in which the channel 322 is engraved. So that it is pinched. According to the membrane-electrode assembly manufacturing method of the third embodiment, the catalyst layer 309A is formed without protruding from the reinforcing member 304A and without forming a gap with the reinforcing member 304A, and the catalyst layer 309B is formed. It is formed without protruding from the reinforcing member 304B and without forming a gap with the reinforcing member 304B. The gas diffusion layer 314A is provided so as to cover the catalyst layer 309A, and the gas diffusion layer 314B is provided so as to cover the catalyst layer 309B. A gap 221 is formed between the gas diffusion layer 314A and the gasket 319A, and between the gas diffusion layer 314B and the gasket 319B, but the gap 321 is not in contact with the polymer electrolyte membrane 312. With this structure, when the gas supplied from the gas diffusion layers 314A and 314B reaches the polymer electrolyte membrane 312, it always passes through the catalyst layer 309A or 309B. Since the catalyst layers 309A and 309B do not protrude above the reinforcing members 304A and 304B, the gas diffusion layer 309A and the reinforcing member 304A directly contact the gas diffusion layer 309B and the reinforcing member 304B, respectively.
[Features and effects]
According to the membrane-electrode assembly manufacturing method of the third embodiment, the reinforcing member is disposed on the periphery of the polymer electrolyte membrane, and the catalyst layer has no gap inside the reinforcing member, as in the second embodiment. The formed membrane-electrode assembly can be produced efficiently. In addition, the adhesion between the reinforcing member and the gas diffusion layer is improved, and the sealing property during stack assembly is also improved. By collecting and reusing the protruding catalyst layer together with the covering member, waste of the catalyst can be prevented.

Further, the third embodiment has the following features and effects. In the first embodiment and the second embodiment, since the catalyst layer is applied to both surfaces of a single polymer electrolyte membrane, the polymer electrolyte membrane is once attached to a suction fixing device (suction fixing by a decompression method) after coating one surface. It is necessary to remove it from the device) and the backing member, invert it and fix it again. When the polymer electrolyte membrane is made of a delicate and easily wrinkled material, the membrane may be severely wrinkled simply by removing it from a suction fixing device (a suction fixing device using a reduced pressure method) or a backing member. According to the membrane-electrode assembly manufacturing method of the third embodiment, a total of two polymer electrolyte membranes are prepared, one on each side, and the reinforcing member is attached while the respective polymer electrolyte membranes are fixed. The catalyst layer can be applied. According to this method, wrinkles of the polymer electrolyte membrane can be effectively prevented.
(Modification)
Examples of possible modifications in the first to third embodiments will be described below. The form (planar shape, thickness, etc.) of the polymer electrolyte, the reinforcing member, and the opening is not particularly limited. The reinforcing member preferably covers the periphery of the polymer electrolyte membrane in a frame shape, but the outer periphery of the reinforcing member and the polymer electrolyte membrane may not coincide. The covering member may not have the same shape as the reinforcing member, but preferably covers at least the periphery of the opening of the reinforcing member (the portion protruding when the catalyst layer is applied). The polymer electrolyte membrane may have a reinforcing membrane inside. The reinforcing member, the catalyst layer, and the gas forming layer may be disposed only on one side of the polymer electrolyte membrane. The order of each process is not restricted to the above-mentioned thing, You may replace. The composite member is not necessarily formed and attached independently of the polymer electrolyte membrane, and the structure in which the polymer electrolyte membrane, the reinforcing member, and the covering member are laminated may be formed in any order. For example, the reinforcing member and the covering member may be sequentially laminated on the polymer electrolyte membrane. In the third embodiment, the polymer electrolyte membrane may be covered only with the reinforcing member without providing the covering member. When the catalyst layer is applied using a suction fixing device (a suction fixing device using a reduced pressure system), the coating may be performed while warming with a heater or the like.
Example 1
Example 1 is an example of Embodiment 3 of the present invention, in which a polymer electrolyte membrane is fixed on a backing member, and a reinforcing member is attached and a catalyst layer is applied thereon. 7A to 7E are process diagrams schematically showing a method for producing a membrane-catalyst layer-gas diffusion layer assembly according to Example 1 of the present invention. FIG. 7A is a diagram showing a state in which the polymer electrolyte membrane is held on the backing member. FIG. 7-B is a diagram showing a state where the reinforcing member and the covering member are attached to the polymer electrolyte membrane. FIG. 7-C is a diagram showing a state in which a catalyst layer is applied from above the covering member. FIG. 7D is a diagram illustrating a state where the covering member is removed. FIG. 7-E is a diagram showing a state in which polymer electrolyte membranes are joined to form a membrane-electrode assembly. FIG. 7-F is a diagram showing a state where a gas diffusion layer is formed on the catalyst layer to form a membrane-electrode-gas diffusion layer assembly. FIG. 7G is a diagram showing a state where a gasket and a separator are joined to the membrane-electrode-gas diffusion layer assembly to form a cell. Hereinafter, the manufacturing method of the membrane-catalyst layer-gas diffusion layer assembly according to Example 1 will be described in detail with reference to FIGS. 7-A to 7-G. The drawings are merely schematic diagrams for illustrating the positional relationship of each member in each process, and the relative size, shape, thickness, and the like are not adjusted to the actual ratio.
[Preparation of membrane]
A PET base material 401A (first backing member) and 401B (second backing member) made of polyethylene terephthalate (PET) having a square shape with a thickness of about 100 μm and a main surface of 200 mm on one side are prepared. The surface was treated with a silicon release agent.

CF ₂ = repeating unit _{CF 2 = CF-OCF 2 CF} (CF 3) based on _{CF 2} -OCF ₂ CF ₂ SO ₃ dispersion of the ion-exchange resin consisting of repeating units based on H (ion exchange capacity: 1. 1 milliequivalent / gram dry resin, trade name: Flemion, manufactured by Asahi Glass Co., Ltd., hereinafter referred to as Dispersion A), and by a die coating method, a thickness of 15 μm and one side of one side of the PET base materials 401A and 401B are prepared. Coating was performed so as to form a 160 mm square. Dispersion A was dried at 90 ° C. for 30 minutes on PET substrates 401A and 401B. Through this step, a base material-membrane assembly 403A in which the polymer electrolyte membrane 402A (first polymer electrolyte membrane) is placed on the PET base material 401A is prepared (first polymer electrolyte membrane holding step). Then, a base material-membrane assembly 403B in which the polymer electrolyte membrane 402B (second polymer electrolyte membrane) was placed on the PET base material 401B was prepared (second polymer electrolyte membrane holding step) (FIG. 7). -A). As a result, the polymer electrolyte membranes 402A and 402B were held and fixed on the PET base materials 401A and 401B, respectively. The adhesion between the polymer electrolyte membranes 402A and 402B and the PET base materials 401A and 401B does not generate wrinkles even when the catalyst layer is applied, and the polymer electrolyte membranes 402A and 401A from the PET base materials 401A and 401B after application. It was suitable in that 402B can be easily removed.
[Fabrication and installation of frame]
Two bases made of polytetrafluoroethylene (PTFE) (hereinafter referred to as PTFE base material) having a thickness of about 100 μm and a main surface having a square of 150 mm were prepared, and the two were joined. The two bonded PTFE substrates were punched with a Thomson type so that a square opening 423A (hole) with a side of 100 mm opened in the center. Accordingly, a multilayer frame 406A (first composite member) having a double structure of a frame body 404A (first reinforcing member) made of a PTFE base material and a mask body 405A (first covering member) made of a PTFE base material. ) Was obtained (first composite member forming step). Similarly, a multilayer frame body having a double structure of a frame body 404B (second reinforcing member) made of a PTFE base material and a mask body 405B (second covering member) made of a PTFE base material and having an opening 423B. 406B (second composite member) was obtained (second composite member forming step). Cutouts for guides were formed on the outer circumferences of the multilayer frames 406A and 406B (see “Lamination of polymer electrolyte membrane”).

The multilayer frame body 406A is placed at the center of the upper surface of the substrate-membrane assembly 403A, and the reinforcing member 404A is not held by the backing member 401A of the polymer electrolyte membrane 402A so that the frame body 404A abuts the polymer electrolyte membrane 402A. Glued with adhesive (as coated). Through this process, a base material-membrane-frame body assembly 407A in which the polymer electrolyte membrane 402A, the frame body 404A, and the mask body 405A were sequentially laminated on the PET base material 401A was produced (first reinforcing member). Arrangement process). Further, the multilayer frame 406B is placed at the center of the upper surface of the substrate-membrane assembly 403B, and the reinforcing member 404B is not held by the backing member 401B in the polymer electrolyte membrane 402B so that the frame 404B contacts the polymer electrolyte membrane 402B. Glued with adhesive (to cover the surface). Through this step, a base material-membrane-frame body assembly 407B in which the polymer electrolyte membrane 402B, the frame body 404B, and the mask body 405B were sequentially laminated on the PET base material 401B was produced (second reinforcing member). Arrangement process) (FIG. 7B).
[Catalyst layer coating]
Dispersion A and a catalyst-supported carbon powder in which 50% by mass of a platinum catalyst having an average particle diameter of about 3 nm is supported on an acetylene black-based carbon powder are mixed with an ethanol and water dispersion medium (1: 1 by mass ratio). 1), a dispersion having a solid content of 14% by mass (hereinafter referred to as electrode catalyst dispersion) was prepared. Next, the electrode catalyst dispersion is applied to the base material-membrane-frame assembly 407A so as to cover the entire surface of the polymer electrolyte membrane 402A exposed in the opening 423A of the multilayer frame 406A without any gaps, and in a mask. Spraying was performed so as to protrude above the body 405A (so as to protrude from the periphery of the opening 423A) (first catalyst layer coating step). Further, the electrode catalyst dispersion is applied to the base material-membrane-frame assembly 407B so as to cover the entire surface of the polymer electrolyte membrane 402B exposed in the opening 423B of the multilayer frame 406B without any gaps, and a mask body Spraying was performed so as to protrude above 405B (so as to protrude into the periphery of the opening 423B) (second catalyst layer coating step). Through this process, the entire surface of the polymer electrolyte membrane 402 exposed to the openings 423A and 423B and a part of the mask bodies 405A and 405B were covered with the electrode catalyst dispersion layer 408 (FIG. 7C).

The electrode catalyst dispersion layers 408A and 408B were dried on the substrate-membrane-frame assembly 407A and 407B at 90 ° C. for 30 minutes, and the mask bodies 405A and 405B were peeled off (first covering member removing step) Second covering member removing step). Through this process, the entire surfaces of the polymer electrolyte membranes 402A and 402B exposed in the openings 423A and 423B of the frames 404A and 404B are respectively covered with the catalyst layers 409A (first catalyst layer) and 409B (second catalyst layer). It became a thing. Through this process, the frame body 404A is laminated on the polymer electrolyte membrane 402A, and the entire surface of the polymer electrolyte membrane 402A exposed to the opening 423A of the frame body 404A is covered with the catalyst layer 409A without any gaps. -The catalyst layer assembly 410A was formed. Also, a membrane-frame-catalyst in which a frame 404B is laminated on the polymer electrolyte membrane 402B, and the entire surface of the polymer electrolyte membrane 402B exposed in the opening 423B of the frame 404B is covered with a catalyst layer 409B without any gaps. A layer assembly 410B was formed. By the above method, the membrane-frame-catalyst layer assemblies 410A, B are held on the PET substrates 401A, 401B, respectively, and the substrate-membrane-frame-catalyst layer assemblies 411A, 411B (FIG. 7). -D) was produced.
[Polymer electrolyte membrane bonding]
A metal rod was fitted vertically into the plate at an interval at which the metal rods were fitted into the cutout portions of the frame bodies 404A and 404B to produce a guide frame. The base material-membrane-frame body-catalyst layer assembly 411B is peeled from the PET base material 401B (second backing member removing step), and the obtained membrane-frame body-catalyst layer assembly 410B is cut out from the frame body. Was fitted in the guide frame so that the polymer electrolyte membrane 402B faced upward. Furthermore, the PET base material 401A is peeled from the base material-membrane-frame body-catalyst layer assembly 411A (first backing member removing step), and the obtained membrane-frame body-catalyst layer assembly 410A is removed from the frame body. The cutout was fitted in the guide frame so that the notch was fitted to the metal rod and the polymer electrolyte membrane 402A was directed downward. The membrane-frame-catalyst layer assemblies 410A and 410B are brought into contact with the guide frame, removed from the guide frame, and joined by hot pressing at about 150 ° C., 50 kg / cm ² for 20 minutes (polymer electrolyte membrane Contact process). By the joining, the polymer electrolyte membranes 402A and 402B were integrated into a single polymer electrolyte membrane 412. After joining, the polymer electrolyte membrane 412 protruding from the frames 404A and 404B was cut off. By fitting the notches into the guide frame, the membrane-frame-catalyst layer assemblies 410A and 410B could be stacked so that no deviation occurred on the outer periphery. By the above method, the peripheral portions on both sides of the polymer electrolyte membrane 412 are reinforced by the frames 404A and 404B, and the entire surface of the polymer electrolyte membrane 412 exposed to the openings 423A and 423B of the frames 404A and 404B is covered by the catalyst layer 409. One membrane-catalyst layer assembly 413 (membrane-electrode assembly) covered without a gap was produced (FIG. 7-E).
[Formation of gas diffusion layer]
A conductive layer having a thickness of about 10 μm made of carbon black and polytetrafluoroethylene particles is formed on one surface of a carbon cloth substrate having a thickness of about 300 μm, and punched into a 104 mm square square with a Thomson type. A carbon cloth 414A (first gas diffusion layer) and 414B (second gas diffusion layer) were produced. The carbon cloth 414A with the conductive layer was disposed so that the conductive layer of the carbon cloth 414A with the conductive layer was in contact with the catalyst layer 409A and covered the entire surface of the catalyst layer 409A (first gas diffusion layer forming step). Further, the carbon cloth 414B with the conductive layer was disposed so that the conductive layer of the carbon cloth 414B with the conductive layer was in contact with the catalyst layer 409B and covered the entire surface of the catalyst layer 409B (second gas diffusion layer forming step). Through this process, the peripheral portions of both surfaces of one polymer electrolyte membrane 412 are reinforced by the frames 404A and 404B, respectively, and the entire surface of the polymer electrolyte membrane 412 exposed to the openings 423A and 423B of the frame is the catalyst layer 409A, Membrane-catalyst layer-gas diffusion layer assembly 415 (membrane-electrode-gas diffusion layer assembly) covered with 409B without gaps, and the entire surfaces of the catalyst layers 409A, 409B are covered with carbon cloths 414A, 414B with conductive layers, respectively. ) Was produced (FIG. 7-F).
[Assembly with gasket and separator]
Two polytetrafluoroethylene (PTFE) base materials (hereinafter referred to as PTFE base materials) having a thickness of about 100 μm and a main surface having a side of 150 mm are prepared, and a square hole having a side of 120 mm is opened in the center. So punched with Thomson type. The obtained PTFE frame was used as gaskets 419A and 419B.

  In addition, two square carbon plates having a thickness of 2 mm and a main surface of 150 mm were prepared, and a flow path snaked with a width of 5 mm and an interval of 7 mm was engraved on one surface of each plate to form a flow path 422. The obtained carbon plates with flow paths were used as separators 420A and 420B.

Gaskets 419A and 419B were attached to both surfaces of the membrane-catalyst layer-gas diffusion layer assembly 415 so as to surround the gas diffusion layers 414A and 414B, respectively. The membrane-electrode-gas diffusion layer assembly 415 and the gaskets 419A, 419B are joined by the separators 420A, 420B so that the respective flow paths 422 are in contact with the gas diffusion layers 414A, 414B, respectively (FIG. 7-). G). The cell 424 was obtained by the above method.
[Check cross section]
The cell 424 obtained as described above was cut along a straight line passing through the openings 423A and 423B, and the cross section was observed with a microscope (an enlarged view portion of FIG. 7-G). As shown in FIG. 7G, no significant gap was observed between the catalyst layer 409A and the frame 404A. Although a gap 421 was observed between the gas diffusion layer (carbon cloth with conductive layer 414A) and the gasket 419A, the gap 421 was not in contact with the polymer electrolyte membrane 412. With this configuration, the fuel gas and the oxidant gas can flow directly from the gas diffusion layer (carbon cloth 414A, 414B with conductive layer) to the polymer electrolyte membrane 412 (without passing through the catalyst layers 409A and 409B). It was confirmed that it can be prevented.
[Modification]
Note that it is not always necessary to use a guide frame and a notch in order to overlap the outer periphery so that no deviation occurs. For example, alignment marks (register marks, etc.) are formed at the four corners, and these marks are confirmed by a CCD or the like. However, favorable results were obtained even when alignment was performed.
(Comparative Example 1)
In Comparative Example 1, a catalyst layer is formed on a polymer electrolyte membrane, and then a frame is attached. 8A to 8E are process diagrams schematically showing a method for producing a membrane-catalyst layer-gas diffusion layer assembly according to Comparative Example 1 of the present invention. FIG. 8-A is a diagram showing a state in which the polymer electrolyte membrane is held on the backing member. FIG. 8-B is a diagram showing a state in which a catalyst layer is applied to the polymer electrolyte membrane. FIG. 8C is a diagram illustrating a state where a frame is attached to the outer periphery of the catalyst layer. FIG. 8-D is a diagram showing a state in which polymer electrolyte membranes are joined to form a membrane-electrode assembly. FIG. 8E is a diagram showing a state where a gas diffusion layer is formed on the catalyst layer to form a membrane-electrode-gas diffusion layer assembly. FIG. 8F is a diagram showing a state where a gasket and a separator are joined to the membrane-electrode-gas diffusion layer assembly to form a cell. Hereinafter, the method for producing the membrane-catalyst layer-gas diffusion layer assembly according to Comparative Example 1 will be described in detail with reference to FIGS.
[Preparation of membrane]
Substrate-membrane assemblies 503A and 503B (FIG. 8A) composed of a PET substrate and a polymer electrolyte membrane were produced by the same method as in the example.
[Catalyst layer coating]
An electrode catalyst dispersion was prepared in the same manner as in the examples. Next, the electrode catalyst dispersion was applied to the center of one main surface of each of the base material-membrane assemblies 503A and 503B by screen printing so that the printed surface was a square having a side of 98 mm. The electrode catalyst dispersion was dried at 90 ° C. for 30 minutes on the substrate-membrane assemblies 503A and 503B. From this step, the catalyst layer was laminated on the polymer electrolyte membrane to form membrane-catalyst layer assemblies 516A and 516B. By the above method, one substrate-membrane-catalyst layer assembly 517A, 517B (FIG. 8-B) in which the membrane-catalyst layer assembly was held on the PET substrate was produced.
[Fabrication and installation of frame]
A polytetrafluoroethylene (PTFE) base material (hereinafter referred to as PTFE base material) having a thickness of about 100 μm and a main surface having a side of 150 mm is prepared, and a square hole (opening) having a side of 100 mm is at the center. The PTFE substrate was punched with a Thomson mold so as to open. As a result, PTFE-based frames 504A and 504B were obtained. As in Example 1, notches for guides were formed on the outer periphery of the frame bodies 504A and 504B.

Frames 504A and 504B are arranged at the center of the main surface of the base material-membrane-catalyst layer assembly 517A, 517B on the side where the polymer electrolyte membrane and the catalyst layer are disposed, and the inner periphery overlaps with the catalyst layers 509A, 509B. It was mounted so as not to become hot, and was hot-pressed at about 150 ° C. for 20 minutes. By the above method, the polymer electrolyte membrane and the frame body are sequentially laminated on the PET base material, and the base material-membrane-frame body-catalyst layer assembly 511A in which the catalyst layer is fitted inside the opening of the frame body. 511B was created (FIG. 8-C).
[Polymer electrolyte membrane bonding]
In the same manner as in the example, the PET substrate 501 was peeled off from each of the substrate-membrane-frame-catalyst layer assembly 511A, 511B, and the polymer electrolyte membrane 502 side was bonded. The membrane-catalyst layer assembly 513 (membrane-electrode assembly) in which the frame bodies 504A and 504B are attached to both surfaces of the polymer electrolyte membrane 512 by bonding and the catalyst layers 509A and 509B are fitted inside thereof is 1 A sheet was produced (FIG. 8-D).
[Formation of gas diffusion layer]
Carbon cloths 514A and 514B with conductive layers were produced in the same manner as in the example. A carbon cloth with a conductive layer 514A is attached on the catalyst layer 509A so that the conductive layer is in contact with the catalyst layer 509A, and a carbon cloth with a conductive layer is provided on the catalyst layer 509B so that the conductive layer is in contact with the catalyst layer 509B. 514B was attached, and one membrane-catalyst layer-gas diffusion layer assembly 515 (membrane-electrode-gas diffusion layer assembly) was produced (FIG. 8-E).
[Assembly with gasket and separator]
Gaskets 519A and 519B and separators 520A and 520B were produced in the same manner as in Example, and were joined to membrane-catalyst layer-gas diffusion layer assembly 515 to obtain cell 524 (FIG. 8-F). .
[Check cross section]
The cell 524 obtained as described above was cut along a straight line passing through the inside of the openings of the frame bodies 504A and 504B, and the cross section was observed with a microscope (enlarged portion of FIG. 8F). As shown in FIG. 8F, in addition to the gap 521 formed between the gas diffusion layer (carbon cloth with a conductive layer 514A) and the gasket 519A, the cross section is between the catalyst layer 509A and the inner periphery of the frame 504A. In addition, a gap 518 of about 1 mm was observed. In such a configuration, fuel gas or oxidant gas directly from the gas diffusion layer (carbon cloth 514A, 514B with conductive layer) to the polymer electrolyte membrane 512 through the gap 518 (without passing through the catalyst layers 509A, 509B). Was expected to flow through.
(Comparison between Example 1 and Comparative Example 1)
In the polymer electrolyte membranes used in Example 1 and Comparative Example 1, when the electrode catalyst dispersion was applied thereon, the polymer electrolyte membrane was greatly expanded and contracted (about 10 to 20 mm per 200 mm). Further, the degree of expansion / contraction varies greatly depending on humidity, film thickness, etc., and it has been difficult to predict how much the expansion / contraction will occur.

  In Comparative Example 1, the catalyst layer was applied before attaching the frame to the polymer electrolyte membrane. Considering the degree of expansion and contraction, in order to prevent the catalyst layer and the frame from overlapping each other, it is necessary to form the catalyst layer at least 1 mm on both sides smaller than the frame, and a gap is inevitably generated.

  On the other hand, in Example 1, a frame was attached before applying the catalyst layer on the polymer electrolyte membrane, and the catalyst layer was applied so as to partially overlap the frame. By this method, there is no gap between the catalyst layer and the frame (the inner periphery of the frame and the outer periphery of the catalyst layer are in contact with each other without a gap), and a structure in which the catalyst layer and the frame are in close contact with each other can be easily obtained. I was able to make it. Moreover, since the catalyst layer did not protrude from the reinforcing member, the adhesion between the reinforcing member and the gas diffusion layer was improved. It was suggested that waste of the catalyst could be prevented if the protruding catalyst layer was collected and reused together with the covering member. When a catalyst layer is applied to a single polymer electrolyte membrane, wrinkles occur due to expansion and contraction, and subsequent processing may be difficult. In Example 1, the generation of wrinkles could be effectively prevented by applying the catalyst layer while the polymer electrolyte membrane was fixed on the PET substrate.

  In the method for producing a membrane-electrode assembly according to the present invention, a reinforcing member is disposed on the periphery of the polymer electrolyte membrane, and a catalyst layer is formed on the inner side of the reinforcing member without any gap. This is useful as a method for efficiently producing a membrane-electrode assembly that is unlikely to be distorted or damaged.

It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 1st Embodiment of this invention, Comprising: It is a figure which shows the state of only a polymer electrolyte membrane. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 1st Embodiment of this invention, Comprising: It is a figure which shows the process in which a reinforcement member is attached to a polymer electrolyte membrane. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 1st Embodiment of this invention, Comprising: The state which became a membrane-electrode assembly by applying the catalyst layer from the reinforcement member is shown. FIG. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 1st Embodiment of this invention, Comprising: A gas diffusion layer is formed on a catalyst layer, and a membrane-electrode-gas diffusion layer assembly and It is a figure which shows the state which became. It is a schematic diagram which shows the cross section in the use condition of the membrane-electrode-gas diffusion layer assembly produced by the membrane-electrode assembly manufacturing method of the first embodiment of the present invention. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 2nd Embodiment of this invention, Comprising: It is a figure which shows the state of only a polymer electrolyte membrane. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 2nd Embodiment of this invention, Comprising: It is a figure which shows the process in which a reinforcement member and a coating | coated member are attached to a polymer electrolyte membrane. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 2nd Embodiment of this invention, Comprising: It is a figure which shows the state by which the catalyst layer was coated from the coating | coated member. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 2nd Embodiment of this invention, Comprising: It is a figure which shows the state from which the coating | coated member was removed. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 2nd Embodiment of this invention, Comprising: A gas diffusion layer is formed on a catalyst layer, and a membrane-electrode-gas diffusion layer assembly and It is a figure which shows the state which became. It is a schematic diagram which shows the cross section in the use condition of the membrane-electrode-gas diffusion layer assembly produced by the membrane-electrode assembly manufacturing method of the second embodiment of the present invention. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 3rd Embodiment of this invention, Comprising: It is a figure which shows the state of only a polymer electrolyte membrane. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 3rd Embodiment of this invention, Comprising: It is a figure which shows the process in which a reinforcement member and a coating | coated member are attached to a polymer electrolyte membrane. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 3rd Embodiment of this invention, Comprising: It is a figure which shows the state by which the catalyst layer was coated from on the coating | coated member. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 3rd Embodiment of this invention, Comprising: It is a figure which shows the state from which the coating | coated member was removed. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 3rd Embodiment of this invention, Comprising: Polymer electrolyte membranes are joined and the figure which shows the state used as the membrane-electrode assembly. is there. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method of 3rd Embodiment of this invention, Comprising: A gas diffusion layer is formed on a catalyst layer, and a membrane-electrode-gas diffusion layer assembly and It is a figure which shows the state which became. It is a schematic diagram which shows the cross section in the use condition of the membrane-electrode-gas diffusion layer assembly produced by the membrane-electrode assembly manufacturing method of the third embodiment of the present invention. It is process drawing which shows typically the manufacturing method of the membrane-catalyst layer-gas diffusion layer assembly by Example 1 of this invention, Comprising: It is a figure which shows the state by which the polymer electrolyte membrane was hold | maintained on the backing member. . It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method by Example 1 of this invention, Comprising: It is a figure which shows the state by which the reinforcement member and the coating | coated member were attached to the polymer electrolyte membrane. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method by Example 1 of this invention, Comprising: It is a figure which shows the state in which the catalyst layer was coated from the coating | coated member. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method by Example 1 of this invention, Comprising: It is a figure which shows the state from which the coating | coated member was removed. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method by Example 1 of this invention, Comprising: The polymer electrolyte membranes are joined and the figure which shows the state used as the membrane-electrode assembly. . It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method by Example 1 of this invention, Comprising: A gas diffusion layer is formed on a catalyst layer, and it becomes a membrane-electrode-gas diffusion layer assembly. FIG. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method by Example 1 of this invention, Comprising: The state which became a cell by joining a gasket and a separator to the membrane-electrode-gas diffusion layer assembly FIG. It is process drawing which shows typically the manufacturing method of the membrane-catalyst layer-gas diffusion layer assembly by the comparative example 1 of this invention, Comprising: It is a figure which shows the state by which the polymer electrolyte membrane was hold | maintained on the backing member. . It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method by the comparative example 1 of this invention, Comprising: It is a figure which shows the state by which the catalyst layer was applied to the polymer electrolyte membrane. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method by the comparative example 1 of this invention, Comprising: It is a figure which shows the state by which the frame was attached to the outer periphery of a catalyst layer. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method by the comparative example 1 of this invention, Comprising: Polymer electrolyte membranes are joined and the figure which shows the state used as the membrane-electrode assembly. . It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method by the comparative example 1 of this invention, Comprising: A gas diffusion layer is formed on a catalyst layer, and it becomes a membrane-electrode-gas diffusion layer assembly. FIG. It is process drawing which shows typically an example of the membrane-electrode assembly manufacturing method by the comparative example 1 of this invention, Comprising: The state which became a cell by joining a gasket and a separator to a membrane-electrode-gas diffusion layer assembly FIG.

Explanation of symbols

102 Polymer electrolyte membrane 104A, 104B Reinforcing member 109A, 109B Catalyst layer 113 Membrane-electrode assembly 114A, 114B Gas diffusion layer 115 Membrane-electrode-gas diffusion layer assembly 119A, 119B Gasket 120A, 120B Separator 121 Gap 122 Flow path 123A, 123B Opening 202 Polymer electrolyte membrane 204A, 204B Reinforcement member 205A, 205B Cover member 206A, 206B Composite member 208A, 208B Catalyst dispersion layer 209A, 209B Catalyst layer 213 Membrane-electrode assembly 214A, 214B Gas diffusion layer 215 Membrane -Electrode-Gas diffusion layer assembly 219A, 219B Gasket 220A, 220B Separator 221 Gap 222 Channel 223A, 223B Opening 302A, 302B Polymer electrolyte membrane 304A, 304B Supplement Member 305A, 305B Cover member 306A, 306B Composite member 308A, 308B Catalyst dispersion layer 309A, 309B Catalyst layer 312 Polymer electrolyte membrane 313 Membrane-electrode assembly 314A, 314B Gas diffusion layer 315 Membrane-electrode-gas diffusion layer assembly 319A, 319B Gasket 320A, 320B Separator 321 Gap 322 Flow path 323 Opening 401A, 401B PET base material 402A, 402B Polymer electrolyte membrane 403A, 403B Base material-membrane assembly 404A, 404B Frame body 405A, 405B Mask body 406A, 406B Multilayer frame 407A, 407B Substrate-membrane-frame assembly 408A, 408B Electrode dispersion liquid layer 409A, 409B Catalyst layer 410A, 410B Membrane-frame-catalyst layer assembly 411A, 411B Substrate-membrane-frame Body Catalyst layer assembly 412 Polymer electrolyte membrane 413 Membrane-catalyst layer assembly 414A, 414B Carbon cloth with conductive layer 415 Membrane-catalyst layer-gas diffusion layer assembly 419A, 419B Gasket 420A, 420B Separator 421 Gap 422 Channel 423A, 423B Opening 424 Cell 501A, 501B PET base material 502A, 502B Polymer electrolyte membrane 503A, 503B Base material-membrane assembly 504A, 504B Frame body 509A, 509B Catalyst layer 511A, 511B Base material- membrane-frame body-catalyst layer joint Body 512 polymer electrolyte membrane 513 membrane-catalyst layer assembly 514A, 514B carbon cloth with conductive layer 515 membrane-catalyst layer-gas diffusion layer assembly 516A, 516B membrane-catalyst layer assembly 517A, 517B base material-membrane-catalyst Layer assembly 518 gap 519A, 19B gasket 520A, 520B separator 521 gap 522 passage 524 cells

Claims (7)

A reinforcing member disposing step in which a reinforcing member having a frame portion so as to surround the opening is provided on the polymer electrolyte membrane so that a peripheral portion of at least one surface of the polymer electrolyte membrane is covered with the frame portion; ,
A catalyst layer coating step of coating a catalyst layer over the entire surface of the polymer electrolyte membrane exposed at least in the opening of the reinforcing member;
A gas diffusion layer disposing step of disposing a gas diffusion layer so as to cover the catalyst layer;
I have a,
The method for producing a membrane-electrode assembly, wherein the catalyst layer coating step is to coat the catalyst layer so that the catalyst layer protrudes from the periphery of the opening when viewed from the thickness direction of the catalyst layer. .   The method for producing a membrane-electrode assembly according to claim 1, wherein in the catalyst layer coating step, the catalyst layer is applied by spraying. Further, a composite member forming step of forming a composite member having the reinforcing member and a covering member that has substantially the same planar shape as the reinforcing member and covers one side of the reinforcing member;
A covering member removing step of removing the covering member from the reinforcing member after applying the catalyst layer,
In the reinforcing member disposing step, the composite member is provided so that the reinforcing member is positioned on the polymer electrolyte membrane side with respect to the covering member,
The method for producing a membrane-electrode assembly according to claim 1, wherein, in the catalyst layer coating step, the catalyst layer is coated so as to protrude from the opening of the composite member to the periphery of the opening.   The said composite member formation process is a membrane-electrode assembly manufacturing method of Claim 3 which forms the said composite member by bonding and punching out two resin sheets. In the reinforcing member disposing step, the first reinforcing member having a frame portion so as to surround the opening is covered with a peripheral portion of at least one surface of the first polymer electrolyte membrane with the frame portion. A first reinforcing member disposing step provided on the first polymer electrolyte membrane; and a second reinforcing member having a frame portion formed so as to surround the opening. A second reinforcing member disposing step provided on the second polymer electrolyte membrane so as to cover a peripheral portion of at least one surface of
The catalyst layer coating step includes a first catalyst layer coating step of coating the first catalyst layer on the entire surface of the first polymer electrolyte membrane exposed at least in the opening of the first reinforcing member; A second catalyst layer coating step of coating a second catalyst layer on the entire surface of the second polymer electrolyte membrane exposed at least in the opening of the second reinforcing member,
Furthermore, the surface of the first polymer electrolyte membrane coated with the first catalyst layer that is not coated with the first catalyst layer, and the second polymer electrolyte membrane that is coated with the second catalyst layer. The method for producing a membrane-electrode assembly according to claim 1, further comprising a polymer electrolyte membrane contact step of contacting a surface of the polymer electrolyte membrane not coated with the second catalyst layer. And a first composite member having a first covering member that has substantially the same planar shape as the first reinforcing member and covers one surface of the first reinforcing member. A first composite member forming step to be formed;
A second composite member is formed having the second reinforcing member and a second covering member that has substantially the same planar shape as the second reinforcing member and covers one surface of the second reinforcing member. A second composite member forming step;
A first covering member removing step of removing the first covering member from the first reinforcing member after applying the first catalyst layer;
A second covering member removing step of removing the second covering member from the second reinforcing member after applying the second catalyst layer,
In the first reinforcing member disposing step, the first composite member is provided such that the first reinforcing member is located closer to the first polymer electrolyte membrane than the first covering member;
In the second reinforcing member disposing step, the second composite member is provided such that the second reinforcing member is located on the second polymer electrolyte membrane side with respect to the second covering member,
In the first catalyst layer coating step, the first catalyst layer is applied so as to protrude from the opening of the first composite member to the periphery of the opening,
The membrane-electrode according to claim 5, wherein, in the second catalyst layer coating step, the second catalyst layer is coated so as to protrude from the opening of the second composite member to the peripheral portion of the opening. Bonded body manufacturing method And a first polymer electrolyte membrane holding step for holding the first polymer electrolyte membrane on one surface of the first backing member;
A second polymer electrolyte membrane holding step of holding the second polymer electrolyte membrane on one surface of the second backing member,
In the first reinforcing member disposing step, the first composite member is formed so that the first reinforcing member covers a surface of the first polymer electrolyte membrane that is not held by the first backing member. A step of providing the first polymer electrolyte membrane;
In the second reinforcing member disposing step, the second composite member is disposed on the second composite member so as to cover a surface of the second polymer electrolyte membrane that is not held by the second backing member. A step of providing the second polymer electrolyte membrane;
A first backing member removing step of removing the first backing member from the first polymer electrolyte membrane coated with the first catalyst layer before the polymer electrolyte membrane contact step; ,
A second backing member removing step of removing the second backing member from the second polymer electrolyte membrane coated with the second catalyst layer before the polymer electrolyte membrane contact step; The method for producing a membrane-electrode assembly according to claim 5.

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