JP4811992B2 - Conductive porous film - Google Patents

Description

  The present invention relates to a conductive porous film.

  Conventionally, for example, a gas diffusion layer used in a polymer electrolyte fuel cell (hereinafter referred to as a fuel cell) has a repellent property between the gas diffusion layer and the catalyst layer in order to adjust moisture at the anode and cathode of the fuel cell. Some are provided with an aqueous porous layer.

  The porous layer needs to have conductivity as well as water repellency. Therefore, as a method of forming the porous layer, a method of forming a porous layer on the carbon paper by applying a dispersion liquid containing carbon and a water-repellent fluororesin to the carbon paper of the gas diffusion layer and sintering it. There is.

Further, the porous PTFE film is used as a substrate as the porous layer, and the catalyst is placed in the pores of the porous PTFE film by immersing the porous PTFE film in a dispersion liquid in which, for example, particulate catalyst layer material is dispersed in an alcohol solvent. A material containing a layer material is disclosed in Patent Document 1.
JP-A-8-213027

  However, the wet coating method in which the dispersion liquid is applied has a problem in that the diffusibility of a reaction gas such as hydrogen or air is lowered by the penetration of the dispersion liquid into the carbon paper.

  In addition, when the porous PTFE film is immersed in a dispersion containing carbon, a water repellent, and a surfactant, alcohol is used as a solvent for the dispersion, and when, for example, PTFE is used as the water repellent, the dispersion Since PTFE fine particles are aggregated, pure water must be used as a solvent. However, since the porous PTFE film repels water, there is a problem that carbon and a water repellent agent do not easily penetrate into the porous PTFE film.

  Further, since carbon particles and PTFE fine particles are immersed in the porous PTFE film, if the PTFE fine particles are sheared by being pushed in with a spatula or sucked from the other, the PTFE fine particles are easily fibrillated. Since the PTFE thus fiberized can easily expand and contract, the rigidity is lost, and there is a problem that such a carbon layer creeps when the fuel cell is repeatedly started and stopped.

  The present invention has been invented to solve such problems. For example, carbon and PTFE particles are present in pores between fibers constituting a porous film made of a fluororesin, for example, a porous PTFE film. An object of the present invention is to obtain a conductive porous film that secures conductivity and gas permeability and has high rigidity.

In the present invention, a conductive material containing at least carbon and particulate Teflon (registered trademark, hereinafter the same) fine particles are contained in a stone wall shape in pores formed between fibers of a porous film made of a fluororesin. .

  In addition, a hydrophilic treatment step for subjecting the conductive porous film to a hydrophilic treatment on a porous film made of a fluororesin, and a conductive material containing at least carbon in a solvent mainly containing water and Teflon fine particles are dispersed. The dispersion is soaked into the pores of the porous film subjected to hydrophilic treatment.

  According to the present invention, conductivity is imparted to a porous film by containing conductive carbon and particulate fluororesin fine particles in pores formed between fibers of a porous film made of a fluororesin. In addition, for example, a conductive porous film excellent in gas diffusibility of a reaction gas such as hydrogen or air can be obtained.

  Since it is constituted by carbon contained in the pores of the porous film and highly rigid fluororesin fine particles, a highly conductive conductive porous film can be obtained.

  Further, the porous film is subjected to a hydrophilic treatment, and then a conductive material containing at least carbon is infiltrated into the pores of the porous film subjected to the hydrophilic treatment, thereby easily producing the conductive porous film. be able to.

  In this embodiment, the conductive porous film is used for a fuel cell, but is not limited to the use of a fuel cell.

  A fuel cell is supplied with an oxidant gas such as air containing hydrogen on one side of the membrane electrode assembly and oxygen on the other side, and generates power by an electrochemical reaction between hydrogen and oxygen. A schematic configuration of a membrane electrode assembly 1 according to an embodiment of the present invention will be described with reference to FIG. The membrane electrode assembly 1 includes an electrolyte membrane 2 and a gas diffusion electrode 3 provided on both main surfaces of the electrolyte membrane 2. The gas diffusion electrode 3 includes a catalyst layer 4 in contact with the electrolyte membrane 2 and a gas diffusion layer 5 provided outside the catalyst layer 4.

  The electrolyte membrane 2 is a proton conductive solid polymer electrolyte membrane, for example, an electrolyte membrane of perfluorosulfonic acid.

  The catalyst layer 4 is composed of a catalyst and an electrolyte. The catalyst may be carbon carrying a catalyst such as platinum or platinum black, and the catalyst layer may further contain carbon or a water repellent.

  The gas diffusion layer 5 will be described with reference to the schematic diagram of FIG. The gas diffusion layer 5 is formed by joining a conductive porous layer 6 and carbon paper 7. Carbon cloth may be used in place of the carbon paper 7. Further, the gas diffusion layer 5 may be composed of only the porous layer 6.

  The porous layer 6 is a layer containing at least conductive carbon 12 and a water repellent 13 inside a porous film 10 made of PTFE (polytetrafluoroethylene) which is a fluororesin. The detail of the porous layer 6 is demonstrated using the schematic of FIG.

  The porous layer 6 contains particulate carbon 12 and a water repellent 13 in pores (voids) 11a formed between the fibers 10a of the porous film 10 by a method described later. The porous film 10 is formed, for example, by stretching PTFE or the like biaxially. The porous film 10 obtained by biaxially stretching PTFE or the like is composed of granular nodes and radially extending fibers 10a, and has a connected porous structure including pores 11a. In addition, a pore 11b having a diameter smaller than that of the pore 11a is formed in the vicinity of the node portion 10b of the fiber 10a. The pores 11b do not contain the carbon 12 and the water repellent 13, and only a reactive gas such as hydrogen or oxygen passes through the pores 11b. That is, by forming the pores 11a containing a large amount of carbon 12 in the porous film 10 and the pores 11b having a diameter smaller than the pore 11a and not containing the carbon 12, the conductivity of the porous film 10 is improved. For example, the diffusibility of the reaction gas such as hydrogen or oxygen can be improved. In addition, it is preferable if the carbon 12 is in a particulate form because the diffusibility of the reaction gas is improved.

  Further, the porous layer 6 uses a water-repellent porous film 10 and further contains a water-repellent agent 13 in the pores 11a in the porous film 10, thereby improving drainage in the gas diffusion layer 5, Flooding can be suppressed. Moreover, since the carbon 12 and the water repellent 13 contained in the pores 11a of the porous film 10 are configured in a stone wall shape, a highly rigid conductive porous film can be obtained.

  The porous film 10 is, for example, a Gore-Tex film manufactured by Japan Gore-Tex. As the carbon 12, for example, carbon powder such as acetylene black or vulcan is used. The water repellent 13 is fluororesin fine particles such as PTFE fine particles. The porous film 10 is not limited to the Gore-Tex film, the porous film 10 is sufficiently thin, has little thickness unevenness, and has a pore size larger than the particle size of the carbon 12 and the water repellent 13 to be contained, In addition, it has a porosity that can give enough carbon to show sufficient electrical conductivity, and it has physical and chemical stability that can withstand the manufacturing process and fuel cell environment. Absent. Further, the carbon 12 and the water repellent 13 are not limited to the above members, and may be any members having conductivity or water repellency.

  With the above configuration, by providing the gas diffusion layer 5 of the membrane electrode assembly 1 with the porous layer 6 having conductivity and water repellency, the power generation efficiency of the fuel cell can be improved and flooding can be suppressed.

  Next, an embodiment of the method for producing the porous layer 6 will be described with reference to the flowchart of FIG.

  In step S100, the porous film 10 is immersed in isopropyl alcohol for several seconds. This replaces the air in the pores 11a and 11b of the porous film 10 with isopropyl alcohol. As the porous film 10, a Gore-Tex film having a thickness of 100 μm and a pore 11 a having a diameter of about 3 μm is used. In this embodiment, isopropyl alcohol is used. However, the present invention is not limited to this. For example, alcohol such as ethyl alcohol may be used.

  In step S101, a surfactant, Triton X100 (registered trademark) manufactured by Dow Chemical Company, is diluted with pure water to prepare a surfactant aqueous solution having a surfactant concentration of 3%, and the surfactant aqueous solution is porous. The quality film 10 is immersed for about 10 seconds. Repeat this 5 times. In step S100, the air in the pores 11a and 11b is replaced with isopropyl alcohol, and the pores 11a and 11b are filled with isopropyl alcohol, so that the surfactant is added to the pores 11a and 11b located inside the porous film 10. It can be easily penetrated.

  Then, it is immersed for about 10 seconds in a surfactant aqueous solution having a new surfactant concentration of 3%. Repeat this 5 times. As a result, the surfactant penetrates into the pores of the porous film 10. The surfactant is not limited to Triton X100.

  In step S102, the porous film 10 impregnated with the surfactant is dried at 50 ° C. A surfactant is attached to the porous film 10 in steps S101 and S102. The porous film 10 is subjected to a hydrophilic treatment through the above steps (Steps S100 to S102 constitute a hydrophilic treatment step).

  In step S103, the dispersion containing carbon 12 and the water repellent 13 is stirred into a solution containing a surfactant using pure water as a solvent to prepare a dispersion (hereinafter referred to as dispersion A). The solid content concentration of the conductive material containing the carbon 12 and the water repellent 13 in the dispersion A is 15%. As the dispersion containing the water repellent 13, for example, Polyflon, D1-E manufactured by Daikin Industries, Ltd. can be used. And the dispersion liquid A is apply | coated to the porous film 10 which performed the hydrophilic treatment, and it is made to dry. This process is repeated three times.

  At this time, as a method for applying the dispersion A, a method in which a prescribed amount is placed on the porous film 10 with a coater or the like, or a method in which the prescribed amount is also placed by a spray or the like is preferable. Since the pores 11a of the porous film 10 are hydrophilized, the dispersion A can be easily immersed in the pores 11a. Here, when an operation of applying a shearing force with a spatula or the like and pushing it into the pores 11a, a part of the water repellent 13 is fibrillated, and the rigidity of the porous layer 6 formed as a result is lowered.

  Here, the porous film 10 in the case of using the present invention and the porous film immersed by applying a shearing force without using the present invention, that is, the water repellent agent in the pores of the porous film were fiberized. The compression amount of the porous film is shown in FIG. FIG. 5 is a diagram showing the results of measuring the change in the compression amount over time by applying a load of 2 MPa to the porous film 10 using the present invention and the porous film not using the present invention. In FIG. 5, when the compression amount changes to the plus side, creep or the like occurs, indicating that the porous film is crushed. Moreover, the change of the compression amount of the porous film 10 using this invention is shown by a solid line, and the change of the compression amount of the porous film when not using this invention is shown by a broken line.

  According to FIG. 5, when not using this invention, the compression amount of a porous film becomes large compared with the case where this invention is used. This is because when the present invention is not used, the PTFE fine particles of the water repellent 13 are made into fibers by being immersed by applying a shearing force, freely expand and contract, and the carbon 12 particles move.

  Here, the solid content concentration is a weight ratio in the dispersion A, and the same applies hereinafter. When the solid content concentration of the dispersion A is high, the carbon 12 and the water repellent 13 do not easily penetrate into the pores 11a of the porous film 10, and when the solid content concentration is low, coating and drying are performed. The number of times of performing the process is increased and workability is deteriorated. Therefore, the solid content concentration is desirably 10% or more and 50% or less. Moreover, when the particle diameter of the carbon 12 in the dispersion A was measured, the average particle diameter of the carbon 12 was about 0.5 μm. If the particle diameter of the carbon 12 is too small, particles of the carbon 12 are also contained in the pores 11b of the porous film 10 and gas diffusibility is lowered. If the particle diameter of the carbon 12 is too large, the pores 11a Since the carbon 12 is difficult to penetrate, the particle size of the carbon 12 is preferably set to 0.4 μm to 0.6 μm.

  By subjecting the porous film 10 to a hydrophilic treatment, the dispersion A containing the carbon 12 and the water repellent 13 can be easily permeated into the pores 11 a in the porous film 10. Thereby, the workability | operativity at the time of manufacturing the porous layer 6 with high electroconductivity is improved, and the electroconductive porous layer 6 can be manufactured easily. In the porous layer 6, the carbon 12 and the water repellent 13 are contained in the porous film 10 so that the weight ratio of the carbon 12 is at least 30% or more. The weight ratio of the carbon 12 is desirably 45% or more (step S103 constitutes a soaking step).

  In step S104, the porous film 10 containing carbon 12 and the water repellent 13 is immersed in isopropyl alcohol five times to remove the surfactant in the porous film 10 (step S104 is a surfactant removing step). Configure).

  In step S <b> 105, the porous film 10 is baked at a temperature of 150 ° C., and isopropyl alcohol attached to the porous film 10 is removed.

  By the above method, carbon 12 and water repellent 13 are contained in the pores 11a of the porous film 10 to obtain a porous layer 6 having good conductivity, good gas diffusibility, and higher strength. it can. In addition, the porous layer 6 is manufactured by the said process using the roll-shaped porous film 10. FIG. By using the roll-shaped porous film 10, workability at the time of manufacturing the porous layer 6 can be improved.

  In this embodiment, the surfactant is removed with isopropyl alcohol, and then the isopropyl alcohol is removed. However, instead of being immersed in isopropyl alcohol, the surfactant may be removed by baking at a temperature equal to or higher than the vaporization temperature of the surfactant. Good.

  Further, when a surfactant whose vaporization temperature of the surfactant is equal to or lower than the melting point of the water repellent 13 is used, the surfactant may be heated at a temperature equal to or higher than the melting point of the water repellent 13. Thereby, the surfactant can be removed and the carbon 12 can be fixed to the porous film 10 using the water repellent 13 as a binder.

  In this embodiment, the porous film 10 was subjected to a hydrophilic treatment in steps S100 to S102. However, ethanol, which is alcohol, and Triton X100 were agitated to prepare a solution having a Triton X100 concentration of 5%. The porous film 10 may be soaked in the solution, and then the porous film 10 may be taken out of the solution and dried in an atmosphere of 50 ° C. to subject the porous film 10 to a hydrophilic treatment. In addition to ethanol, alcohol such as acetone, benzene, or the like may be used.

  Further, Triton X100 is diluted with pure water and stirred to prepare a surfactant aqueous solution having a solid content concentration of 4%. The porous film 10 is submerged in this solution and fixed with a glass weight or the like. Then, after the porous film 10 submerged in the solution is decompressed, it is returned to normal pressure. Thereafter, the porous film 10 may be taken out of the solution and dried in an atmosphere at 50 ° C. to subject the porous film 10 to a hydrophilic treatment. Thereby, for example, the roll-like porous film 10 can be subjected to a hydrophilic treatment at a time, and workability can be improved.

  The gas diffusion layer 5 is formed by laminating a porous layer 6 and a carbon paper 7 having a thickness of 160 μm, and heating and pressurizing at a temperature equal to or higher than the melting point of the water repellent 13. In this embodiment, the porous layer 6 and the carbon paper 7 are integrally formed by heating and pressing under conditions of 360 ° C. and 2 MPa for 60 seconds. Thereby, the porous layer 6 and the carbon paper 7 are joined. In the porous layer 6, the carbon 12 can be fixed to the porous film 10 by the water repellent 13.

  The catalyst layer 4 includes a dispersion liquid (hereinafter referred to as dispersion liquid B) in which a catalyst-supporting carbon that supports a catalyst such as platinum and an electrolyte that is a component of the electrolyte membrane 2 are dispersed in alcohol or a liquid containing alcohol and water. Is applied to the surface of the porous layer 6 having a smooth surface of the gas diffusion layer 5 and then dried. At this time, it is desirable to apply the gas diffusion layer 5 while being fixed by suction or tape. As a coating method of the dispersion B, for example, spray coating, die coater, doctor blade, roller transfer, or the like is used. Note that the electrolyte contained in the dispersion B is not limited to the components of the electrolyte membrane 2. For the catalyst layer 4, the coating step of applying the dispersion B and the drying step of drying may be alternately performed a plurality of times. In the drying step, it is desirable to dry in a ventilated atmosphere, an incombustible gas atmosphere, or a reduced pressure atmosphere. Further, it may be exposed to pure water after drying, and the alcohol component may be eluted and then dried again.

  As described above, the gas diffusion electrode 3 composed of the catalyst layer 4 and the gas diffusion layer 5 is formed. Note that a dispersion liquid in which a catalyst such as platinum, carbon black, and an electrolyte are dispersed in a liquid containing alcohol or alcohol and water may be used as the dispersion liquid B.

  After the gas diffusion electrode 3 is formed by the catalyst layer 4 and the gas diffusion layer 5, the gas diffusion electrode 3 is disposed so that the catalyst layer 4 is in contact with both main surfaces of the electrolyte membrane 2, and the temperature is higher than the glass transition of the electrolyte. Heat and pressurize with. Thereby, the membrane electrode assembly 1 is formed by integrating the electrolyte membrane 2 and the gas diffusion electrode 3.

  By the above method, the membrane electrode assembly 1 having the gas diffusion electrode 3 containing the carbon 12 in the pores 11a of the porous layer 6 and having good conductivity and good gas diffusibility can be formed.

  In this embodiment, the catalyst layer 4 is formed on the surface of the porous layer 6 of the gas diffusion layer 5 in which the conductive porous film or the porous layer 6 made of the conductive porous film and the carbon paper 7 are integrated. Although formed, the porous layer 6 is biaxially stretched, the dispersion B is applied, and the catalyst is applied to the pores having a newly expanded diameter, which are newly formed by the stretching. The layer 4 may be formed.

  Alternatively, the dispersion A may be applied to one surface of the porous film 10 and the dispersion B may be applied to the other surface. Thereby, the carbon 12 and the water repellent 13 may be contained on one surface of the porous film 10, and the catalyst-supporting carbon and the electrolyte may be contained on the other surface of the porous film 10.

  Further, as shown in FIG. 6, the catalyst-supporting carbon 21 and the electrolyte 22 are contained in the pores 24 a of the porous film 20 different from the porous film 10 of the porous layer (first conductive porous film) 6. Thus, the catalyst layer (second conductive porous film) 23 may be formed without containing the catalyst-supporting carbon 21 and the electrolyte 22 in the pores 24b having a diameter smaller than that of the pores 24a.

  Then, the gas diffusion layer 5 and the catalyst layer 23 are laminated and heated and pressurized under the conditions of 130 ° C. and 2 MPa, thereby integrating the gas diffusion layer 5 and the catalyst layer 23 as shown in FIG. In the case where the gas diffusion layer 5 and the catalyst layer 23 are integrated, it is desirable to heat at a temperature equal to or higher than the glass transition point of the electrolyte contained in the catalyst layer 23.

  The effect of the embodiment of the present invention will be described.

  The porous film 10 is, for example, a biaxially stretched PTFE film or the like, and includes a granular node portion 10b and radially extending fibers 10a, and has a connected porous structure. When carbon 12 or water repellent 13 is applied thereto, the carbon 12 or water repellent 13 enters the larger pores 11a in the pores made of nodes and fibers, and the corners of the fine pores 11b and the pores 11a. Remains void. The gas diffusibility is improved by the voids, and the structure of the gas diffusion layer is maintained by the porous base material, so that the durability is improved.

  By setting the weight ratio of the carbon 12 in the porous layer 6 to 30% or more, the conductivity of the porous layer 6 can be improved, for example, the power generation efficiency of the fuel cell can be improved.

  By containing the water repellent 13 in the porous film 10, the drainage property in the porous layer 6 can be improved, and flooding in a high humidity state can be suppressed.

  When the porous layer 6 is manufactured, the porous film 10 of the porous layer 6 is subjected to a hydrophilic treatment, and then the dispersion A containing the conductive carbon 12 and the water repellent 13 is applied to the porous film 10. And dry. As a result, carbon 12 can be easily imparted into the pores 11 a of the porous film 10, the porous layer 6 having good conductivity can be easily manufactured, and work for manufacturing the porous layer 6 The sex can be improved.

  The hydrophilic treatment is performed by first immersing the porous film 10 in, for example, isopropyl alcohol. By replacing the air in the pores 11a and 11b of the porous film 10 with isopropyl alcohol in advance, an aqueous solution containing a surfactant can be easily impregnated in the pores 11a and 11b. After impregnating the pores 11a and 11b with the surfactant aqueous solution, the porous film 10 is dried, so that the inner surfaces of the pores 11a and 11b are covered with the surfactant, thereby the inner surfaces of the pores 11a and 11b. Hydrophilicity can be imparted to the.

  In dispersion A in which carbon 12 and water repellent 13 are dispersed in pure water, the solid content concentration of carbon 12 and water repellent 13 is set to 10% or more by weight ratio of dispersion A, whereby the dispersion The number of times A is applied can be reduced to improve workability, and by setting it to 50% or less, carbon 12 or the like can be easily infiltrated into the pores 11a of the porous film 10.

  When the porous layer 6 and the carbon paper 7 are integrated, by heating and pressing at a temperature higher than the melting point of the water repellent 13, the water repellent 13 serves as a binder to join the porous layer 6 and the carbon paper 7 together. can do. Further, the carbon 12 in the porous layer 6 can be fixed.

  Since the porous layer 6 is formed using the porous film 10 having a smooth surface, the catalyst layer 4 is made thin and uniform even when the dispersion B containing the catalyst or the like is applied to the surface of the porous layer 6. The gas diffusion electrode 3 that can be formed, has excellent gas diffusibility, and has sufficiently small thickness unevenness can be obtained.

  When the dispersion layer B is applied to one surface of the porous layer 6 to form the catalyst layer 4, the constituent material of the porous layer 6 and the catalyst layer 4 is applied to the base material in a liquid state. Since the mass layer 6 and the catalyst layer 4 are integrated without a gap, the gas diffusion electrode 3 can be formed without a gap between the gas diffusion layer 5 and the electrode (catalyst layer 4). This can prevent a decrease in power generation efficiency of the fuel cell due to the gap.

  It goes without saying that the present invention is not limited to the above-described embodiments, and includes various modifications and improvements that can be made within the scope of the technical idea.

  For example, it can be used for automobiles, digital cameras, personal computers, sensors, and the like.

It is a schematic block diagram of the membrane electrode assembly which shows embodiment of this invention. It is a schematic block diagram of the gas diffusion layer which shows embodiment of this invention. It is a schematic block diagram of the porous layer which shows embodiment of this invention. It is a flowchart which shows the manufacturing method of the porous layer of embodiment of this invention. It is a figure which shows the relationship between time passage and the compression amount of a porous film. It is a schematic block diagram of the catalyst layer which shows the example of a change of embodiment of this invention. It is a schematic block diagram of the gas diffusion layer and catalyst layer which show the example of a change of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Membrane electrode assembly 2 Electrolyte membrane 3 Gas diffusion electrode 4 Catalyst layer 5 Gas diffusion layer 6 Porous layer (conductive porous film, 1st conductive porous film)
7 Carbon paper 10, 20 Porous film 10a Fiber 11a, 11b, 24a, 24b Pore 12 Carbon 13 Water repellent 21 Catalyst-supporting carbon 22 Electrolyte 23 Catalyst layer (second conductive porous film)

Claims (18)

A conductive porous film comprising a conductive material containing at least carbon and particulate fluororesin fine particles in a stone wall shape in pores formed between fibers of a porous film made of a fluororesin .   The conductive porous film according to claim 1, wherein a weight ratio of carbon to the conductive porous film is 30% or more. A hydrophilization treatment step for subjecting a porous film made of a fluororesin to a hydrophilic treatment;
Soaking a dispersion in which a conductive material containing at least carbon in a solvent mainly containing water and fluororesin fine particles are dispersed in the pores of the porous film subjected to the hydrophilic treatment; A method for producing a conductive porous film, comprising:   In the hydrophilization treatment step, the porous film is immersed in alcohol, and after the alcohol is filled in the pores, the alcohol in the pores is replaced with a solution containing a surfactant, The method for producing a conductive porous film according to claim 3, wherein the solution containing the surfactant is dried.   The method for producing a conductive porous film according to claim 3, wherein in the hydrophilization treatment step, the porous film is immersed in alcohol containing a surfactant and dried.   The hydrophilization treatment step is performed by immersing the porous film in a solution containing a surfactant, reducing the atmosphere of the porous film, returning to normal pressure, and drying. A method for producing a conductive porous film.   The method for producing a conductive porous film according to claim 3, wherein the step of soaking comprises immersing the porous film subjected to the hydrophilic treatment in the dispersion and then drying.   The conductive porous according to any one of claims 4 to 7, further comprising a surfactant removing step of removing the surfactant attached to the porous film after the step of soaking. Quality film manufacturing method.   The method for producing a conductive porous film according to claim 8, wherein the surfactant removing step removes the surfactant by washing the porous film with alcohol.   9. The conductive porous according to claim 8, wherein the surfactant removing step removes the surfactant by baking the porous film at a temperature equal to or higher than a vaporization temperature of the surfactant. A method for producing a film. The surfactant is a surfactant having a vaporization temperature equal to or lower than the melting point of the fluororesin fine particles,
The said surfactant removal process heats the said porous film at the temperature more than melting | fusing point of the said fluororesin microparticles | fine-particles, The manufacturing of the electroconductive porous film of Claim 9 or 10 characterized by the above-mentioned. Method. The step of soaking comprises the step of drying the porous film after soaking the dispersion into the pores of the porous film,
The method for producing a conductive porous film according to any one of claims 3 to 11, wherein the step of soaking is performed a plurality of times.   The weight ratio of the solid content of the conductive material in the dispersion is 10% or more and 50% or less when the solvent and the conductive material are combined to be 100%. The manufacturing method of the electroconductive porous film as described in any one of 1-12.   The conductive porous film according to claim 1 or 2 and carbon paper or carbon cloth are laminated, heated and pressurized at a temperature equal to or higher than the melting point of the fluororesin fine particles, the conductive porous film, A method for producing a gas diffusion layer, characterized by integrating carbon paper or carbon cloth.   A gas diffusion electrode, wherein a catalyst and an electrolyte are applied to the surface of the conductive film of the gas diffusion layer produced by the method according to claim 14. The carbon and fluororesin are included in the pores on one surface of the conductive porous film according to claim 1 or 2,
A gas diffusion electrode, wherein the pores on the other surface of the conductive porous film contain an electrolyte and carbon and a catalyst, or the electrolyte and a catalyst-supporting carbon. The first conductive porous film according to claim 1 or 2,
A gas diffusion electrode characterized by laminating and integrating an electrolyte, carbon, and a catalyst, or a second conductive porous film containing the electrolyte and catalyst-carrying carbon, in the pores of the porous film. Production method.   A membrane electrode assembly, wherein the gas diffusion electrode according to claim 15 or 16 is provided on both surfaces of an electrolyte membrane.

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