JP2018018665A - Gas diffusion layer base material and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas diffusion layer base material which is improved in permeability of moisture or gas while maintaining strength and also to provide a method of manufacturing the same.SOLUTION: Disclosed is a method for obtaining a gas diffusion layer base material 1 by undergoing a papermaking of a conductive base material 10 made of carbon fibers and a pulp 20 together (S10), impregnating a phenolic resin 30 into a papermaking base material 40 (S30) after the pulp 20 is extinguished by heating of the formed papermaking base material 40 (S20), and thereafter, performing carbonization and graphitization of the phenolic resin 30 by predetermined heat-firing (S50). In the gas diffusion layer base material 1, the weight per unit area is 30 g/cm2, and when dry nitrogen gas is made to flow through one side of the surface in the thickness direction at the flow rate of 10 L/min, the difference in pressure between the front and back is within a range of 0.01-0.3 MPa.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a base material for a fuel cell gas diffusion layer for diffusing a reaction fluid used in a power generation reaction of a fuel cell, and in particular, a gas diffusion layer base having improved moisture and gas permeability while maintaining strength. The present invention relates to a material and a manufacturing method thereof.

  2. Description of the Related Art A fuel cell, in particular, a polymer electrolyte fuel cell whose use is expanded as a power source for automobiles and the like is configured by laminating a plurality of fuel cell separators, and a single cell. In general, an electrode catalyst layer made of a conductive material such as carbon carrying a catalyst such as platinum and an ion exchange resin on both sides of a polymer electrolyte membrane that selectively transmits specific ions, and an electrode catalyst layer A cathode (+) side electrode and an anode (−) side electrode constituted by a porous gas diffusion layer (GDL) disposed on the outside of the membrane are disposed, and a membrane / electrode assembly (MEGA) Diffusion Layer Assembly). In addition, a gas flow path for supplying fuel gas (anode gas) or oxidizing gas (cathode gas) and discharging generated gas and excess gas is formed outside the gas diffusion layer constituting the membrane / electrode assembly. And a membrane / electrode assembly is sandwiched between the separators.

  In the gas diffusion layer of the polymer electrolyte fuel cell having such a structure, the function of diffusing the fuel gas or the oxidizing gas supplied from the gas flow path formed in the separator to the catalyst layer adjacent to the gas diffusion layer (gas diffusion) Gas permeability is required, and conductivity is also required as a current collecting function for moving electrons for electrochemical reaction. Furthermore, in order to maintain the stable power generation performance of the battery by keeping the polymer electrolyte membrane and the catalyst layer in an optimal wet state at all times and suppressing the flooding phenomenon (the phenomenon that the pores of the gas diffusion layer are blocked by water). In addition, moisture permeability is required to discharge excess reaction product water and dew condensation water generated by the electrochemical reaction of hydrogen and oxygen during power generation. Of course, thermal and chemical stability and physical strength for protecting the polymer electrolyte membrane and the catalyst layer are also required.

  In particular, from the aspects of gas diffusivity and moisture management of electrolyte membranes and electrode assemblies, the gas and moisture permeability of the gas diffusion layer is a very important physical property. It is possible to supply a sufficient amount of gas, and it is possible to prevent water clogging of the electrode, which causes the gas diffusibility by blocking the gas flow path, thereby improving the water discharge performance at the electrode. Enable output. Especially in applications where a high power density is required for vehicles such as automobiles, the reaction conditions are high because the gas is pressurized and the operating conditions are in a high current region (region where the current density is high). About the gas diffusion layer, in order to efficiently supply gas, and also to increase the amount of water generated, it is easy for flooding, which is a wet phenomenon, to occur because the amount of water generated increases. Requires high moisture and gas permeability.

As a gas diffusion layer for a fuel cell, generally, a base material formed into a sheet or the like using conductive fibers such as carbon fibers is used. A treatment (for example, formation of a coating layer made of carbon fine particles or a water repellent) is performed to improve conductivity and water repellency.
Here, in order to improve the function of the gas diffusion layer, in order to increase moisture and gas permeability in the base material of the gas diffusion layer, pulp or the like is added to the base fiber such as carbon fiber, and the pulp disappears by heating. A method of forming a porous substrate by making a mark into a hole has been proposed.
Moreover, in order to improve the electroconductivity etc. of a gas diffusion layer base material, the technique of couple | bonding base fibers, such as carbon fiber, with carbides, such as resin, is known.

  For example, in Patent Document 1, pulp and phenol resin are added to carbon fiber, a sheet-shaped molding material is made by a papermaking method, a predetermined number of layers are stacked, pressed and cured, and further obtained It is disclosed that a carbon substrate for a fuel cell is obtained by subjecting the molded plate to carbonization treatment such as carbonization and graphitization in a high-temperature heating furnace.

  Further, in Patent Documents 2 to 4, after carbon fibers are impregnated with a thermosetting resin into carbon fiber sheets formed with an aggregate made of paper made of pulp or thermoplastic resin (hereinafter referred to as pulp or the like). A technique for producing a gas diffusion layer base material that has been heated and fired and carbonized is disclosed.

Hei 11-185770 2013-16476 gazette Hei 8-59360 2005-297547

  Thus, in order to improve the desired characteristics in the gas diffusion layer base material, in Patent Document 1, paper is made together with carbon fiber, pulp, and phenol resin, and in Patent Documents 2 to 4, together with carbon fiber. It has been proposed to impregnate a papermaking body on which pulp or the like is made with a thermosetting resin.

  However, in the technique of Patent Document 1, paper is made with a resin together with carbon fiber and pulp. In the techniques of Patent Documents 2 to 4, pulp and the like are present together with carbon fiber in the carbon fiber sheet impregnated with the resin. Therefore, the resin tends to adhere and adsorb to the pulp and the like. For this reason, although the pulp etc. disappears by heating and baking during resin carbonization, a large amount of resin carbide is distributed and remains on the disappearance trace (the trace where the pulp etc. existed), filling the gap of the disappearance trace (filling) ) Therefore, the volume of voids of disappearance traces of pulp or the like cannot be increased, and there is a limit to increasing moisture and gas permeability.

On the other hand, the inventors' experimental studies confirmed that moisture and gas permeability were improved by reducing the amount of pulp made with carbon fiber while keeping the amount of resin unchanged.
However, reducing the amount of pulp reduces the strength during papermaking, and the sheet is damaged in continuous papermaking where a large tensile force acts on the sheet when the sheet is wound around the roll or conveyed by the roll. This makes it difficult to form a long sheet, resulting in a decrease in productivity.
Furthermore, although moisture permeation and gas permeability can be improved by reducing the basis weight, that is, the thickness, in this case, the strength is lowered and the handling method is limited.

  Then, this invention makes it a subject to provide the gas diffusion layer base material which can improve the permeability | transmittance of a water | moisture content or gas, and its manufacturing method.

  The method for producing a gas diffusion layer base material according to claim 1 is characterized in that the disappearance in the papermaking base material in the disappearance step is performed following the papermaking step in which the conductive base material and the disappearing material are made together to form the papermaking base material. After the material has disappeared, the paper base material from which the disappeared material has disappeared is impregnated with a carbon precursor resin in a resin impregnation step, and then impregnated into the paper base material in a carbonization / graphitization step The carbon precursor resin thus obtained is carbonized and graphitized.

The paper making step is a step of making a paper together with the conductive base material and the disappearing material, and forms a paper base material such as a sheet which is a precursor of the gas diffusion layer base material.
Here, the above disappearing material is thermally decomposed by heating in the next disappearing step and disappears (burns out), and the disappeared traces become pores (pores, pores) that serve as gas and moisture channels of the gas diffusion layer base material. ). Moreover, it has a function as a binder which connects an electroconductive base material in a papermaking stage. For example, fibrillated materials such as pulp (plant fiber) that is easily pyrolyzed by low-temperature heating, has little residue, and has a high function as a binder are particularly suitable.

Moreover, the said disappearance process is a process of making the said loss | disappearance material paper-made with the said electroconductive base material lose | disappear by heating. Thus, the paper-making base material having a void (hole) due to the disappearance trace of the disappearing material and made of an aggregate of the conductive base material is obtained.
Further, the resin impregnation step includes carbonizing the papermaking substrate comprising the aggregate of the conductive substrate after the disappearance material has disappeared by heating and baking in a non-oxidizing atmosphere in the next carbonization / graphitization step. A step of impregnating the carbon precursor resin to be graphitized. Usually, a resin solution (dispersion) or a resin film is supplied to the papermaking substrate and a resin is added to the papermaking substrate.

In the carbonization / graphitization step, the carbon precursor resin in the papermaking substrate is obtained by drying and heating the papermaking substrate impregnated with the carbon precursor resin, followed by carbonization firing in a non-acidic atmosphere. Is a step of carbonizing and graphitizing the material.
Here, in the carbonization / graphitization, the temperature condition of heating and firing is set according to the purpose of the gas diffusion layer base material, desired characteristics, resin characteristics, etc., and it does not matter whether carbonization or graphitization is distinguished.
The non-oxidizing atmosphere means an atmosphere that is not widely oxidizable, and is usually in an inert gas such as nitrogen (N ₂ ) gas, argon (Ar) gas, or helium gas. Embedded in carbon powder such as activated carbon in a reducing atmosphere such as in carbon monoxide (CO) gas, hydrogen (H ₂ ) gas, in a vacuum, in an atmosphere such as carbon dioxide gas, or in an enclosed space It also includes methods.
In the drying and heating, moisture and solvent in the papermaking substrate are removed before carbonization and firing, and the resin is cured as necessary.

  In the method for producing a gas diffusion layer base material according to claim 2, the conductive base material is made of carbon fiber, the disappearing material is made of pulp (plant fiber), and the resin is made of a phenol resin.

The gas diffusion layer base material according to claim 3 is a paper base formed by paper making together a conductive base material and a disappearing material that has a binder function to bind the conductive base material and can be lost by heating. After the material is heated to eliminate the disappearing material in the paper base material, the paper base material composed of the aggregate of the conductive base materials is impregnated with a carbon precursor resin, and predetermined drying and heating are performed. Since the resin was carbonized and graphitized by heating and baking in a non-oxidizing atmosphere later, the conductive base material was bound by the resin carbide, and the predetermined voids were formed by the disappearance of the disappearing material. Yes, on the front and back of the gas diffusion layer substrate when dry nitrogen gas was passed at a flow rate of 10 L / min from one surface in the thickness direction of the gas diffusion layer substrate with a basis weight (basis weight) of 30 g / cm ² The differential pressure is 0.01 to 0.3 MPa, more preferably The pressure is in the range of 0.01 to 0.2 MPa, more preferably 0.01 to 0.08 MPa.

  Here, the resin carbide is formed by carbonization / graphitization of a carbon precursor resin such as a phenol resin by heating and baking (made by carbonizing and graphitizing the resin), and binds the conductive base material. It is a substance. As the carbon precursor resin, a phenol resin or the like is preferable because it has a strong binding force to a conductive substrate such as carbon fiber and a large residual weight during carbonization.

  According to the method for producing a gas diffusion layer substrate according to the invention of claim 1, after making a papermaking substrate by making a paper together with the conductive substrate and the disappearable material in the papermaking step, After the papermaking substrate is heated to dissipate the disappearing material in the papermaking substrate, the disappearing material disappears in the resin impregnation step, and the papermaking substrate comprising the aggregate of conductive substrates is carbonized. After impregnating a possible carbon precursor resin and drying and heating the papermaking substrate impregnated with the resin in the carbonization / graphitization step, the papermaking substrate in the non-oxidizing atmosphere is heated at a high temperature. Carbonize and graphitize the resin.

  Thus, before the paper making base material is impregnated with the resin in the resin impregnation step, the disappearing material in the paper making base material formed by making the paper together with the conductive base material and the disappearing material is lost in the disappearance step. In addition, it is possible to avoid a situation in which the resin remains on the disappeared trace of the lost material due to the resin adhering to and adsorbed on the lost material, thereby blocking or filling the lost track, and a predetermined pore volume can be secured in the disappeared track of the lost material. . Therefore, the moisture and gas permeability of the gas diffusion layer base material is improved.

  In this way, by impregnating the paper making base material from which the disappearing material has disappeared with the resin, the resin can be uniformly distributed on the conductive base material, and a predetermined pore volume is ensured in the disappearing trace of the disappearing material. By doing so, it is possible to improve the moisture and gas permeability without reducing the use of the lost material that causes a decrease in strength, and to secure a sufficient amount of the lost material. Therefore, when a paper is made together with the conductive base material by using a predetermined amount of the disappearing material, an appropriate strength can be secured, so that continuous paper making can be easily performed.

  According to the method for producing a gas diffusion layer substrate according to the invention of claim 2, the conductive substrate is made of carbon fiber, the vanishing material is made of pulp (plant fiber), and the resin is made of a phenol resin. From the above, in addition to the effect of claim 1, high strength of the gas diffusion layer base material is obtained by the carbon fiber, and the residue is easily lost by heating at a low temperature condition by the pulp (plant fiber). The void volume and porosity of the disappearance trace can be increased, and high moisture and gas permeability can be obtained. Furthermore, the phenol resin has a high carbonization rate, and the phenol resin carbide has a strong binding force with a conductive substrate such as carbon fiber, whereby the conductivity and strength of the gas diffusion layer substrate can be increased.

The gas diffusion layer base material according to claim 3 is formed by binding a conductive base material with a resin carbide, forming a predetermined pore, and being porous, with a basis weight (basis weight) of 30 g / cm ^2. In the above, the pressure difference between the front and back of the gas diffusion layer when dry nitrogen gas is allowed to flow from one surface in the thickness direction of the gas diffusion layer substrate at a flow rate of 10 L / min is within a range of 0.01 to 0.3 MPa. is there.

As a result of the inventors' diligent experimental research, a paper-making base material formed by paper-making together a conductive base material and a disappearing material that has a binder function for linking the conductive base material and can be lost by heating. On the other hand, first, the disappeared material in the papermaking substrate is disappeared by heating, and then impregnated with a carbon precursor resin that can be carbonized, and then heated and fired in a non-oxidizing atmosphere after drying and heating. By carbonizing and graphitizing the resin in the paper base material, the conductive base material is bound by the resin carbide, and predetermined voids are formed by disappearance of the lost material before impregnation with the resin, and Difference in front and back of the gas diffusion layer base material when dry nitrogen gas is passed at a flow rate of 10 L / min from one surface in the thickness direction of the gas diffusion layer base material with a basis weight (basis weight) of 30 g / cm ² The pressure is in the range of 0.01 to 0.3 MPa. A porous gas diffusion layer base material having high gas permeability could be obtained.

  This is because, by impregnating the resin with the papermaking base material from which the disappearing material has disappeared, the resin does not adhere to or adhere to the disappearing material, so that the disappearance material disappears and the carbide derived from the resin blocks the disappearance material. This is because a situation of filling or the like is avoided, and a predetermined hole volume is secured in the disappeared trace of the lost material. And since it is possible to secure a predetermined pore volume in the disappearance trace of the disappearing material in this way, it is possible to improve the permeability of moisture and gas without reducing the use of the disappearing material that causes a decrease in strength. When the paper is made together with the conductive base material, a sufficient strength is ensured. Therefore, continuous paper making is also possible.

Accordingly, the differential pressure between the front and back sides of the gas diffusion layer is 0.01 to 0.3 MPa when dry nitrogen gas is allowed to flow from one surface in the thickness direction of the gas diffusion layer substrate at a flow rate of 10 L / min. The inner gas permeability can be achieved even under a weight per unit area of 30 g / cm ² , and the moisture and gas permeability are increased while maintaining the strength.

  Here, when the differential pressure is less than 0.01, gas permeability becomes excessively high, and when used for an electrode of a fuel cell for an automobile that requires high power density, for example, high temperature operation conditions Below, drying of the polymer film is likely to proceed, which may reduce battery performance. On the other hand, when the differential pressure exceeds 0.3, the gas permeability is low, so that the output improvement effect is small in an automobile fuel cell that requires a high output density. When the differential pressure is in the range of 0.01 to 0.3 MPa, a high output can be stably obtained in a fuel cell for automobiles that require a high output density. Preferably it is in the range of 0.01 to 0.2 MPa, more preferably in the range of 0.01 to 0.08 MPa.

FIG. 1 is a flowchart showing a method for manufacturing a gas diffusion layer substrate according to an embodiment of the present invention. FIG. 2 is a photograph of the microscope (reference is 200 μm) of the sheet surface (surface in a direction perpendicular to the thickness direction of the sheet) of the gas diffusion layer substrate according to Example 1 of the present embodiment. FIG. 3 is a microscope (reference is 200 μm) photograph of the sheet surface (surface in the direction perpendicular to the sheet thickness direction) of the gas diffusion layer substrate according to Comparative Example 1. 4 is a photograph of the microscope (reference is 200 μm) of the sheet surface (surface in the direction perpendicular to the thickness direction of the sheet) of the gas diffusion layer substrate according to Comparative Example 2. FIG. FIG. 5 is a conceptual diagram for explaining the gas permeability test.

[Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, since the same symbol and the same code | symbol mean the same or the equivalent functional part in embodiment, the detailed description which overlaps is abbreviate | omitted here.
First, the manufacturing method of the gas diffusion layer base material of embodiment of this invention is demonstrated with reference to FIG.
In the present embodiment, as shown in the flowchart of FIG. 1, first, the conductive base material 10 and the disappearing material 20 are made together in the paper making process (step S <b> 10) to form the paper making base material 40. .

  Examples of the conductive substrate 10 include carbon-based and metal-based materials, but in consideration of thermal and chemical stability (corrosion resistance, conductivity, etc.), carbon fibers (carbon fibers, carbon fibers), carbon particles are preferable. (Carbon particles). As long as it is a conductive substance having conductivity, it may be in the form of fibers or particles, and both carbon fibers and carbon particles can be used in combination, but carbon fiber is the main component from the viewpoint of strength and papermaking properties. Is preferred.

  Examples of the carbon fiber include polyacrylonitrile (PAN) -based carbon fiber, pitch-based carbon fiber, rayon-based carbon fiber, phenol-based carbon fiber, and the like. One type may be used alone, or two or more types may be used in combination. May be. It is selected according to the desired properties of the papermaking substrate 40 and the gas diffusion layer substrate 1. From the viewpoint of strength and the like, polyacrylonitrile-based carbon fibers and pitch-based carbon fibers are preferable. In particular, when the carbon fiber to be used is only polyacrylonitrile-based carbon fiber, the strength of the gas diffusion layer substrate 1 becomes extremely high. On the other hand, when polyacrylonitrile-based carbon fiber and pitch-based carbon fiber are used in combination, the elasticity and flexibility of the papermaking substrate 40 can be ensured.

  The conductive fibers such as carbon fibers may be short fibers or long fibers, but carbon short fibers are preferable in consideration of dispersibility, ease of papermaking (yield), and the like. In addition, when the fiber length is short, it is possible to suppress an excessively long passage (hole, pore, pore) serving as a gas permeation path or a water discharge path in the gas diffusion layer substrate 1. You can acquire various directions of the passage. As a result, it is advantageous for allowing gas and moisture to permeate in a direction in which it is easy to escape, and it becomes possible to increase the permeability of gas and moisture. In addition, it is advantageous for moderate moisture retention. The short fibers may be short fibers obtained by cutting continuous long fibers, or the continuous long fibers are stirred in a dispersion medium such as water by a stirrer (for example, a mixer or a slashfiner). It may be obtained by shortening the fiber.

  The length and diameter of the conductive fiber (single fiber) such as carbon fiber can be appropriately selected. However, considering the dispersibility, the strength of the gas diffusion layer substrate 1 to be formed, the average fiber diameter is, for example, It is in the range of 1 to 60 μm, preferably 3 to 30 μm, more preferably 4 to 20 μm. In particular, if the average fiber diameter is in the range of 4 to 20 μm, more preferably in the range of 5 to 15 μm, high gas and moisture permeability can be secured in the formed gas diffusion layer substrate 1. Furthermore, 3 to 9 μm is preferable from the viewpoint of production cost and dispersibility, and 4 to 8 μm is preferable from the viewpoint of smoothness and conductivity of the gas diffusion layer substrate 1. In the case of carbon fibers having a flat cross section, the average of the major axis and the minor axis is defined as the fiber diameter.

  The average fiber length of the conductive fibers (single fibers) is, for example, in the range of 0.2 to 50 mm, preferably 1 to 30 mm, more preferably 3 to 25 mm, more preferably 5 to 15 mm. In particular, 2 to 12 mm is preferable, and more preferably in the range of 3 to 9 mm from the viewpoints of capture properties by the disappearing material 20 at the time of paper making and binding properties by the resin carbide described later. Further, if the fiber length is in the range of 3 to 20 mm, more preferably in the range of 4 to 10 mm, the dispersibility at the time of papermaking is good, and the conductive substrate 10 is less likely to slip through the papermaking body, and its blending amount. Adjustment and control are easy and the papermaking property is good. Furthermore, the sheet-like papermaking substrate 40 is uniform with little unevenness in the basis weight, and the strength of the gas diffusion layer substrate 1 can be increased. In addition, by using two or more types of fibers having different average diameters and average lengths, it is easy to adjust and control characteristics such as surface smoothness, conductivity, strength, and the like of the gas diffusion layer substrate 1.

  The vanishing material 20 decomposes and disappears by predetermined heating, and the disappeared traces form pores (pores, pores) that serve as gas and water passages of the gas diffusion layer base material 1, and paper making It only needs to function as a binder that sometimes connects the conductive base materials 10 together, for example, pulp (plant fibers) such as wood, cellulose, cotton, bamboo and hemp, animal fibers such as wool, polylactic acid, Examples thereof include resin fibers such as polyvinyl alcohol (PVA), polyethylene, polyolefin, polypropylene, polyurethane, polyester, nylon, vinylon, acrylic, aramid, polyacetal, and novoloid. These may be used individually by 1 type and may use 2 or more types together. In the case of wet papermaking, one that does not dissolve in a dispersion medium described later is selected.

  The vanishing material 20 may be in the form of particles, lumps, etc., but the trapping property of the conductive substrate 10 is good and the papermaking yield can be increased to facilitate papermaking, and papermaking with the conductive substrate 10 is possible. From the above, it is possible to improve the entanglement property and the reinforcing property of the conductive substrate 10 in the papermaking substrate 40, and thus a fibrous organic substance is preferable.

And among the above-mentioned, pulps such as wood that have high thermal decomposability and little residue when heated under relatively low temperature conditions (temperature that does not cause deterioration of the conductive substrate 10, preferably 500 ° C. or less). Polylactic acid fibers and the like are suitable.
In particular, pulp fibers such as wood are almost decomposed and disappeared under low-temperature heating conditions, and have high affinity with carbon fibers as the conductive substrate 10, and also have good water absorption. This is advantageous for moderate dispersibility, capture property, entanglement property, and contact property, and can prevent the conductive base material 10 from slipping through the paper body, facilitating adjustment and control of the blending amount of the conductive base material 10, and paper making. And the strength of the papermaking substrate 40 can be increased. Then, the conductive base material 10 is supported on the papermaking base material 40 to prevent the conductive base material 10 from dropping and peeling off, and the shape retention of the papermaking base material 40 can be improved. 1 can be obtained. In addition, since the conductive substrate 10 can be prevented from dropping off and reinforcing in this way, it is advantageous to increase the blending ratio of the conductive substrate 10 and increase the conductivity. Furthermore, since the conductive base material 10 is less likely to break due to the dispersion of the conductive base material 10, it is possible to prevent a decrease in power generation performance due to the conductive base material 10 being pierced into the polymer film of the fuel cell. In addition, pulp fibers such as wood are easy to handle and inexpensive. Therefore, it is optimal as the vanishing material 20.

Further, the lost material 20 is more preferably fibrillated by disaggregation / beating. By fibrillation, the entanglement property and contact property of the conductive substrate 10 can be improved, and the strength and shape retention of the papermaking substrate 40 can be further increased.
Fibrilization is a phenomenon in which fibrils inside the fiber appear on the surface due to frictional action and become fuzzy. In addition, “beating” means “pulp slurry is made to pass through a continuous compression / release process by passing the pulp slurry between rotating concavity and convexity blades such as refiners and beaters. To cause swelling, fibrillation, and cutting ”(Chemical Handbook, Applied Chemistry (6th edition), page 250, published by Maruzen Co., Ltd., January 30, 2003) . The beating method is not particularly limited, and may be fibrillated by a pulper, pressurized water jet (water jet punching) or the like.

  By making such a vanishing material 20 together with the conductive base material 10, the dispersibility of the conductive base material 10 is increased during papermaking to prevent re-convergence, and the capture ability of the conductive base material 10 is improved during papermaking. The predetermined strength is maintained by being increased and the conductive base material 10 is bound, and the conductive base material 10 is prevented from falling off and peeling off after paper making. Moreover, it is suppressed that the orientation of the fibrous conductive base material 10 changes after papermaking.

  The blending amount of the conductive base material 10 and the disappearing material 20 depends on the type, size and shape, and desired properties of the gas diffusion layer base material 1 (strength, conductivity, electrical resistance, thermal conductivity, gas diffusibility, The water retention rate, drainage, etc.) are set in consideration, but preferably the blending amount of the disappearing material 20 is 40 parts by weight to 300 parts by weight with respect to 100 parts by weight of the conductive substrate 10. More preferably, it is 100-250 weight part, More preferably, it is 125-200 weight part. Within this range, it is possible to secure sufficient strength (tensile strength, etc.) that can withstand continuous paper making, continuous paper making is easy, productivity can be increased, and cost can be reduced. Is possible.

And in this Embodiment, the papermaking base material 40 is formed by paper-making together such an electroconductive base material 10 and the loss | disappearance material 20 in a papermaking process (step S10).
Examples of a method for papermaking the conductive base material 10 and the disappearing material 20 include a wet papermaking method in which the conductive base material 10 and the disappearing material 20 are dispersed in a dispersion medium, or a conductive base material 10 and the disappearing material in the air. Papermaking can be carried out by a dry papermaking method in which 20 is dispersed and accumulated, but a wet papermaking method is preferred from the viewpoint of uniformity, strength, productivity, controllability of basis weight, and the like.

In the wet papermaking method, paper is made by dispersing the conductive substrate 10 and the disappearing material 20 in a dispersion medium (papermaking medium). As the papermaking process at this time, a known method can be adopted. The solid content (conductive group) can be obtained by squeezing a mixture (slurry) in which the conductive base material 10 and the disappearing material 20 are dispersed using a separating member such as a net-like member or by vacuum suction or drying. The material 10 and the disappearing material 20) and the dispersion medium are separated, and the solid-state conductive base material 10 and the disappearing material 20 can be accumulated (assembled) to form the papermaking base material 40. More specifically, for example, the paper base 40 can be obtained by supplying to a wet paper machine having wires such as a long net, a short net, a circular net, etc., dewatering in a dewatering part, and pressurizing and squeezing water. it can.
As the dispersion medium at this time, water is generally adopted, but depending on the case, an organic solvent such as toluene, xylene, cyclohexane, alcohol or the like may be used.
Moreover, the preparation method of the said mixture is not ask | required in particular, For example, it is also possible to mix and disperse a papermaking component using rotary apparatuses, such as a pulper.

  In addition, it is preferable that the density | concentration of the electroconductive base material 10 and the loss | disappearance material 20 in a dispersion medium exists in the range of 1-50 g / L. If it is the said density | concentration range, productivity will be good, and also dispersibility of the electroconductive base material 10 and the loss | disappearance material 20 will be favorable, and aggregation of the electroconductive base material 10 and the loss | disappearance material 20 will not generate | occur | produce easily. A uniform paper-making base material 40 with a small variation is obtained.

  In the present embodiment, a thin sheet-like (paper-like) papermaking substrate 40 is formed by papermaking. Thus, by forming in sheet form, it can respond to thickness reduction of the electrode for fuel cells. In particular, since the papermaking substrate 40 is formed into a sheet by papermaking, the productivity is good, the papermaking substrate 40 has a large surface area, is homogeneous, has high strength and hardness, is easy to handle, and has a separator and a catalyst layer. It is ideal for use in fuel cell electrodes.

  In addition, there are continuous paper making methods and batch-type methods for paper making. However, continuous paper making is preferred because the basis weight is easily controlled and productivity can be increased. In particular, in the present embodiment, as will be described later, moisture or gas permeability (air permeability) of the gas diffusion layer base material 1 is eliminated by eliminating the disappearing material 20 before impregnating the carbon precursor resin 30. High permeability can be obtained without reducing the amount of the disappearing material 20 that also functions as a binder that binds the conductive base material 10. For this reason, it is possible to secure a sufficient amount of the disappearing material 20, it is possible to ensure sufficient strength and tensile resistance that can withstand continuous paper making by blending a predetermined amount of the disappearing material 20, and a sheet-like continuous paper making is possible. Easily possible. In other words, paper making using a continuous paper making apparatus, conveyance while winding between a plurality of rolls, and winding, without damaging the paper making base material 40, and good roll conveyance property that can be wound into a roll shape. Can be formed.

In this way, a sheet-like papermaking base material (gas diffusion layer base material precursor) 40 is formed by papermaking the conductive base material 10 and the disappearing material 20 together. The basis weight (weighing) of the sheet-like papermaking substrate 40 at this time is, for example, 10 to 200 g / m ² , and the thickness is, for example, 20 to 400 μm.

In the case of carrying out the present invention, a binder (glue agent, paper strength enhancer) such as polyvinyl alcohol, polyvinyl acetate, polyethylene, etc., is used to enhance papermaking properties, bondability (strength), etc. as necessary. It is also possible to use polyolefin such as polypropylene, polyester such as polyethylene terephthalate, polyacrylonitrile, cellulose, polyethylene oxide, polyacrylamide, styrene-butadiene rubber, starch, corn starch and the like. Such a binder may be mixed at the time of paper making and may be wet-made with the conductive substrate 10 and the disappearing material 20 or may be impregnated after paper making. By using a binder, it is possible to enhance the binding properties of the papermaking components, prevent the falling off, and improve the shape retention, handling and handling properties. However, due to the presence of the binder, the carbon precursor resin 30 to be impregnated in the subsequent resin impregnation step (step S30) adheres to the binder, resulting in uneven distribution, or the binder adheres to the disappearing material 20. If the disappearance trace is closed or buried, the moisture and gas permeability may be reduced. Therefore, a binder that is thermally decomposed by heat treatment in the next disappearance step (step S20) is suitable.
However, by using pulp or the like as the disappearing material 20, more preferably by using fibrillar pulp or the like, it has a function of enhancing the bonding of the conductive base material 10, so that the binder is substantially used. Even if it does not add, the papermaking base material 40 formed by making the conductive base material 10 and the disappearing material 20 has high strength and shape retention.

  In the case of carrying out the present invention, entanglement processing by mechanical entanglement method (needle punching method, etc.), high pressure liquid injection method (water jet punching method, etc.), high pressure gas injection method (steam jet punching method, etc.), etc. It is also possible to increase the strength, handling property, conductivity, etc. of the papermaking substrate 40 by entanglement of the conductive substrate 10 in three dimensions. Such an entanglement process can also improve the strength and shape-retaining property of the paper-making substrate 40 obtained by paper-making the conductive substrate 10 and the disappearing material 20. Furthermore, an operation for controlling the degree of orientation of the fiber may be performed by adjusting the dehydration rate of the dispersion medium. Further, the paper quality of the sheet-like papermaking substrate 40 may be adjusted, for example, by compressing the papermaking substrate 40 made by a paper machine through a roll.

Furthermore, if necessary, a fiber that becomes a carbon source that can be carbonized similarly to the resin 30 such as a phenol resin by high-temperature heat treatment in the carbonization / graphitization step (step S50) described later, for example, an acrylic polymer (acrylic fiber, For example, a paper made of a polyacrylonitrile fiber), a cellulosic polymer (cellulosic fiber such as rayon, polynosic fiber, etc.), a phenolic polymer (phenolic fiber) or the like may be made together with the conductive substrate 10 and the disappearing material 20.
In addition, for example, the papermaking substrate 40 can be formed using a flocculant, a viscosity modifier, a surfactant, and the like.

  Next, the papermaking substrate 40 obtained by making both the conductive substrate 10 and the disappearing material 20 in this way is heated at a predetermined temperature in the disappearing step (step S20), thereby making the papermaking substrate. The disappearing material 20 in 40 is lost.

  In the heat treatment in the disappearing step (step S20), heating conditions (temperature, time, atmosphere, etc.) that can decompose and disappear the disappearing material 20 are set according to the type of the disappearing material 20 and the like. Here, when the heating temperature is too high, the conductive substrate 10 is deteriorated. On the other hand, when the heating temperature is too low, the productivity is lowered. For example, when the vanishing material 20 is wood or cellulose pulp, the heating temperature is set to 200 to 500 ° C., preferably 350 ° C. to 450 ° C. There is no possibility of deteriorating the material 10.

  By the heat treatment in the disappearing step (step S20), the disappearing material 20 in the paper making base material 40 is decomposed and disappeared, and the disappearance trace of the disappearing material 20 becomes a void, whereby pores (pores, Pores) are formed, and the porosity (porosity, porosity) is increased. The voids that are disappeared traces function as gas vents and moisture passage holes in the fuel cell. Further, the disappearance material 20 disappears and becomes voids, so that the impregnation property (carbon permeability) of the carbon precursor resin 30 impregnated in the next resin impregnation step (step S30) is enhanced by the voids of the disappearance trace. Therefore, even a small amount of the carbon precursor resin 30 can be uniformly distributed to enhance the properties such as a predetermined strength in the gas diffusion layer substrate 1. The heat treatment may be a batch type or a continuous type.

Subsequently, the paper making base material 40 from which the disappearing material 20 has disappeared in this way is subjected to carbonization / graphitization (hereinafter, without distinction) in a high heat treatment described later in the resin impregnation step (step S30). Carbon precursor resin 30 (also referred to as “carbonization”) (hereinafter also simply referred to as “resin 30”) is impregnated.
Specifically, the carbon precursor resin 30 impregnated into the papermaking substrate 40 in the resin impregnation step (step S30) is carbonized by high heat treatment in a non-oxidizing atmosphere in the carbonization / graphitization step (step S50) described later. And a resin that becomes a conductive carbide (resin that becomes a carbon source), for example, phenol resin, furan resin, epoxy resin, melamine resin, imide resin, urethane resin, aramid resin, urea resin, unsaturated polyester Examples thereof include thermosetting resins such as resin and pitch. Among them, a phenol resin that is easy to handle, easily remains as a conductive substance after carbonization, has a high carbonization rate, and has a strong binding force for binding the conductive substrate 10 such as carbon fiber is preferable.

  Examples of the phenol resin include resol type phenol resin, cresol type phenol, xylenol resin and the like in addition to phenol. In particular, resole phenolic resins obtained by the reaction of phenols (phenol, resorcin, cresol, xylol, etc.) and aldehydes (formaldehyde, paraformaldehyde, furfural, etc.) in the presence of ammonia-based catalysts are the cause of fuel cell durability degradation. This is preferable in that it does not contain a metal component.

  The compounding amount of the resin 30 such as a phenol resin to be carbonized is set according to the characteristics of the gas diffusion layer substrate 1, but the ratio of the resin carbide in the gas diffusion layer substrate 1 is 10 to 90% by mass, Preferably, if it is in the range of 15 to 80% by mass, the conductivity and strength of the gas diffusion layer substrate 1 are sufficiently high. More preferably, if it is in the range of 15 to 40% by mass, and more preferably 20 to 40% by mass, the gas diffusion layer substrate 1 has high moisture and gas permeability. In addition, deformation due to thermal shrinkage during carbonization is small, and shape retention is improved. For example, the resin amount (solid content) of the phenol resin as the resin 30 impregnated in the papermaking substrate 40 is 20 to 150 parts by weight, more preferably 100 parts by mass of the conductive substrate 10 such as carbon fiber. By setting it as 30-80 weight part, it can adjust to the ratio of the above-mentioned resin carbide.

  In the papermaking substrate 40 impregnated with the resin 30 that can be carbonized by heating such as a phenol resin, the carbonization / graphitization step (step S50) after the subsequent drying / heating step (step S40) is performed. By carbonizing the resin 30 such as a phenol resin by heat baking treatment (high temperature, non-oxidizing atmosphere), the conductive substrate 10 is bound by the resin carbide to form a strong conductive path, and the gas diffusion layer The conductivity, strength, and shape retention of the substrate 1 can be improved.

  As a method for impregnating the papermaking substrate 40 made of the aggregate of the conductive substrate 10 with the disappearance material 20 disappearing, the papermaking substrate in a resin solution (resin dispersion) is used as the resin 30 such as phenol resin. 40, a method of immersing 40, a method of applying a resin solution (resin dispersion) to the papermaking substrate 40 (kiss coating method, dipping method, spraying method, curtain coating method, roller contact method, etc.), a resin film as a papermaking substrate For example, a method of transferring the image to 40 is described. The resin 30 is appropriately selected depending on the properties, addition amount, and the like of the resin 30. From the viewpoint of productivity and uniformity, the resin 30 is immersed in the papermaking substrate 40 by immersing the papermaking substrate 40 in a solution (dispersion) of the resin 30. Is preferably impregnated. Alternatively, the solution (dispersion liquid) of the resin 30 may be uniformly applied to the entire papermaking substrate 40 by a squeezing method (dip-nip method or the like) using a squeezing device. It is also possible to adjust and control the amount of resin 30 to be impregnated by changing the roll interval of the squeezing device, and the paper base 40 can be uniformly impregnated with the resin 30.

In the impregnation of the resin 30 as described above, the resin 30 is usually dissolved in a solvent such as alcohols (ethanol or the like), ketones (acetone or the like), toluene, or a resin dispersed in a dispersion medium such as water. A dispersion or the like is used. For example, a phenol resin uses an alcohol such as methanol, ethanol or butyl alcohol, or a solvent (dispersion medium) such as water.
The impregnation treatment with the resin 30 may be a batch type or a continuous type.

When the present invention is carried out, a conductive material such as carbon particles may be included in the resin solution and impregnated with the resin 30 as necessary in order to increase conductivity.
In addition, as appropriate, in order to prevent the conductive substrate 10 from dropping off or peeling off, a binder (glue), for example, polyvinyl alcohol, polyvinyl acetate, polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, poly A resin such as ethylene oxide or polyacrylamide may be impregnated into the papermaking substrate 40 in the resin impregnation step (step S30).

Next, the papermaking substrate 40 impregnated with the predetermined resin 30 is dried and heated in a drying / heating process (step S40).
In the present embodiment, the solvent in the papermaking substrate 40 impregnated with the solution (dispersion) of the resin 30 in the resin impregnation step (step S30) by the drying / heating treatment in the drying / heating step (step S40). (Dispersion medium), water is evaporated, and the resin 30 is cured.

Drying / heating methods include, for example, non-contact using equipment such as a hot air furnace that circulates and supplies hot air, an atmospheric furnace that uses a high-temperature heater, an IR furnace that uses an infrared heater, and a microwave furnace that uses a microwave. There are a method, a contact method in which a heated roll or hot plate is contacted and dried.
In a non-contact method such as a method of blowing hot air in a hot air furnace or the like, operability and maintenance are easy, and it is possible to prevent the conductive base material 10 and the resin 30 from falling off due to contact with a heat source.
On the other hand, for example, in a contact method such as a method of hot pressing in the thickness direction (hydraulic press, hot press, belt press, roll press, etc.), the surface smoothness of the papermaking substrate 40 is particularly high when heating while applying surface pressure. It is possible to improve the contact with peripheral layers such as a catalyst layer when incorporating into a fuel cell. If the pressing pressure is increased more than necessary, the pores may be filled with the resin 30, and the papermaking substrate 40 becomes dense, making it difficult for gas generated during heating and firing to be discharged. There is a risk of deformation and damage. For this reason, the heating temperature and the molding pressure are set in consideration of deterioration, breakage, dropout, etc. of the conductive substrate 10 and permeability. In addition, a continuous paper press 40 (roll press, hydraulic head press, etc.) can be continuously pressed (for example, a press pressure of 0.01 to 2 MPa) to produce a long papermaking substrate 40, and productivity Also good.

  In the present embodiment, the temperature during drying and heating is set to a temperature at which the solvent (dispersion medium) and moisture can be evaporated and the resin 30 can be cured. For example, if it is a phenol resin, the papermaking base material 40 will be dried and heat-treated within the range of 120-300 degreeC under air | atmosphere. If it is in the said range, a solvent and a water | moisture content will be fully removed in a short time (for example, 3 to 10 minutes), the resin 30 can be hardened, and the fall of the intensity | strength by deterioration of the electroconductive base material 10, etc. may be caused. Nor.

  Thus, in the present embodiment, the thermosetting resin 30 such as a phenol resin is cured before carbonization in the next carbonization / graphitization step (step S50), thereby suppressing vaporization of the resin 30 during carbonization. Fixing, and improving the contact between the conductive substrate 10 and the resin 30, further preventing deformation, and improving the strength of the gas diffusion layer substrate 1 to be formed and the bonding property with the surrounding layers. It becomes possible.

However, when carrying out the present invention, the temperature condition during drying / heating may be set to a temperature at which the resin 30 does not cure, and the resin 30 may not be cured in the drying / heating process (step S40). Is possible. When the phenol resin or the like is not cured, for example, the solvent (dispersion medium) or the like is evaporated by performing drying and heat treatment within a range of 60 to 120 ° C. in which the solvent and moisture can be removed in a short time. If the drying / heating time is too long, a large-scale drying furnace is required for continuous drying / heating, which increases costs and reduces productivity. Therefore, the drying / heating time is, for example, 1 minute to 60 minutes.
The drying / heating treatment may be a batch type or a continuous type.

Subsequently, the papermaking substrate 40 thus dried and heat-treated is subjected to a high-temperature firing treatment in the carbonization / graphitization step (step S50).
In the carbonization / graphitization step (step S50), the temperature of the papermaking substrate 40 is, for example, 1000 to 3000 ° C., preferably 1200 to 2500 ° C. in a non-oxidizing atmosphere such as inert treatment (inert gas). Then, the resin 30 impregnated in the previous resin impregnation step (step S30) is carbonized and graphitized by performing a heating and baking treatment for 10 minutes to 1 hour. If the maximum temperature during carbonization is too low, there will be less expression of strength and conductivity, and if the maximum temperature during carbonization is too high, the fiber strength of the conductive substrate 10 will deteriorate and fine powder will be produced. May occur. More preferably, it is heated in a temperature range of 1500 to 2500 ° C., more preferably 1700 to 2300 ° C., thereby reducing impurities in the papermaking substrate 40 and reducing electrical strength such as conductivity without losing strength. Specific resistance) and corrosion resistance can be improved. The heat treatment time at the maximum temperature is preferably 0.5 to 20 minutes. The heat treatment under an inert treatment (inert gas) atmosphere includes a heat treatment at 300 to 800 ° C. (pretreatment; pre-baking and precarbonization) and a heat treatment at 1000 to 3000 ° C. (main treatment; post-treatment). Carbonization and graphitization) can also be performed in multiple stages. Here, the heating and firing conditions are set according to the types of the conductive base material 10 and the resin 30, the desired properties (conductivity, etc.) of the gas diffusion layer base material 1, and the like. There is no difference between carbonization and graphitization.

  By such a high-temperature baking treatment, the resin 30 such as phenol resin is carbonized, and the conductive base material 10 is bound by the carbonized resin, that is, the resin carbide to form a strong conductive path, and gas diffusion The conductivity and strength of the layer substrate 1 can be increased. Thereby, when this gas diffusion layer base material 1 is used as an electrode for a fuel cell, it is possible to reduce electrical resistance, improve current collection, and improve the performance of the fuel cell.

The inert atmosphere can be obtained by circulating an inert gas such as nitrogen gas, argon gas, or helium gas in the heating furnace. Depending on the case, it is also possible to carry out a heat-firing process under an atmosphere of carbon dioxide gas or the like under vacuum.
The carbonization treatment may be performed using a batch-type carbonization furnace or a continuous carbonization furnace, and may be continuously performed by heating and baking (running the papermaking substrate 40 continuously). If it is a continuous type, the gas diffusion layer substrate 1 can be obtained with high productivity and low cost. Furthermore, when a long gas diffusion layer substrate 1 is obtained, when a fuel cell is manufactured, the subsequent steps (for example, formation of a microporous layer, bonding with a catalyst layer, manufacture of a membrane-electrode assembly) are also performed. Continuous processing is possible, fuel cells can be manufactured with high productivity, and costs can be reduced.

  Thus, the papermaking substrate 40 impregnated with the resin 30 such as phenol resin is carbonized in the carbonization / graphitization step (step 50), whereby the conductive substrate 10 is bound by the resin carbide, It becomes the gas diffusion layer base material 1 with enhanced conductivity and strength. Such a gas diffusion layer base material 1 also has elasticity and the like because the conductive base material 10 is bound with resin carbide, and has a dimension absorbability when joined to an electrolyte membrane in application to a fuel cell. high.

In the present embodiment, since the conductive base material 10 such as carbon fiber is made together with a predetermined amount of the disappearing material 20 such as pulp, the strength of the paper making base material 40 is good and the disappearing material 20 is lost. Since the shape-retaining property is good even after the formation, the sheet-like papermaking substrate 40 is formed with a thickness from the papermaking stage, and a plurality of sheets are laminated and adjusted to constitute the gas diffusion layer substrate 1 Even if not, it is possible to use one sheet for the drying / heating step (step S40) and the carbonization / graphitization step (step S50). In this case, there is no fear of delamination, and a thermocompression treatment step for laminating is not particularly required, so that it can be manufactured at low cost.
However, the papermaking substrate 40 is thinned at the papermaking stage, and then a plurality of sheet-like papermaking substrates 40 are laminated and heated and pressed to bond them, followed by a drying / heating step (step S40) and a carbonization / graphitization step. You may use for (step S50). At this time, the papermaking substrates 40 having different properties can be laminated depending on the types of the papermaking components.

Moreover, when implementing this invention, you may provide a shaping | molding process after a drying / heating process (step S40) or a carbonization / graphitization process (step S50) as needed. For example, it can be formed by a method in which smooth rigid plates are applied to both surfaces of the gas diffusion layer substrate 1 and heat-pressed in the thickness direction, a continuous roll press device, a method using a continuous belt press device, or the like. By such press molding (heat pressure molding), the surface of the gas diffusion layer substrate 1 can be smoothed and the thickness can be equalized, and when it is incorporated in a fuel cell, it contacts with a peripheral layer such as a catalyst layer. The contact resistance can be reduced by improving the property. In addition, even if protrusions such as fiber frays are present on the surface of the diffusion layer substrate 1, it can be suppressed by pressing. In addition, the orientation of the conductive substrate 10 is adjusted by pressurization, and the contact property and entanglement of the conductive substrate 10 and the resin carbide (derived from the resin 30) can be improved. 1 can be improved in conductivity and strength. Furthermore, moisture and gas permeability can be adjusted. In addition, the heating temperature and the molding pressure in the heat and pressure molding at this time are set in consideration of deterioration, breakage, dropout, and the like of the conductive base material 10 and, for example, within a range of 120 to 300 ° C. The molding pressure is, for example, in the range of 0.01 to 10 MPa.
In particular, as will be described later, in the present embodiment, the resin carbide derived from the resin 30 is prevented from remaining in the pores formed by the disappearance of the disappearing material 20, so that a high porosity and large voids are obtained. Since the pore volume (hole diameter) can be secured, high moisture and gas permeability can be obtained even if a predetermined pressing is performed.

  Incidentally, the thickness of the gas diffusion layer substrate 1 is, for example, in the range of 50 to 300 μm, preferably 70 to 250 μm. Within this range, it has moderate strength, good hand linkability, easy transport, good coating operability and coating properties for forming a coating layer (microporous layer), and moderate Electrical resistance and desired moisture and gas permeability can be ensured.

As described above, in the present embodiment, the paper making process for forming the sheet-like paper making base material 40 by making the paper together with the conductive base material 10 such as carbon fiber and the disappearing material 20 such as pulp (step S10). Then, after the sheet-like papermaking substrate 40 obtained is heated to perform the disappearing step (step S20) for erasing the disappearing material 20 in the papermaking substrate 40, the papermaking substrate 40 is formed. A carbon impregnation step (step S50) is performed in which a resin impregnation step (step S30) for impregnating the resin 30 is carried out, followed by predetermined drying and heating in the drying and heating step (step S40), followed by high-temperature firing in a non-oxidizing atmosphere. By carrying out the above, the gas diffusion layer substrate 1 is manufactured.
According to the gas diffusion layer substrate 1 formed by such a manufacturing method, a predetermined high porosity and a large pore volume (pore diameter) are ensured, and high moisture and gas permeability is obtained.

  This is provided with a disappearing step (step S20) for disappearing the disappearing material 20 in the papermaking substrate 40 before the resin impregnation step (step S30), and impregnating the resin 30 with respect to the disappearing material 20 to which the resin 30 is easily attached and adsorbed. By eliminating the resin 30 from the papermaking base 40 before making it adhere, adsorption / adsorption of the resin 30 to the lost material 20 is avoided, and there are many resin carbides derived from the resin 30 in the voids (holes) of the disappeared trace of the lost material 20. This is because the pore volume is prevented from decreasing due to residual and distributed.

  Thus, in this embodiment, the absence of the disappearing material 20 in the papermaking substrate 40 impregnated with the resin 30 avoids the concentration of the distribution of the resin 30 in the voids of the disappeared trace of the disappearing material 20. In addition, it is avoided that the resin carbide derived from the resin 30 blocks or fills the voids of the disappearance material 20, and a large pore volume and a high porosity can be obtained in the gas diffusion layer substrate 1, and moisture and gas can be obtained. The permeability of is increased. Therefore, when applied to a fuel cell, it is possible to improve the diffusibility of gas and the ability to discharge excess water, and the output of the fuel cell can be improved.

And, by impregnating the paper-making base material 40 from which the vanishing material 20 has disappeared in this manner with the resin 30, the void volume and porosity of the voids formed by the disappearance of the vanishing material 20 are maintained, By securing a large pore volume and a high porosity, moisture and gas permeability can be increased without reducing the vanishing material 20 having a binder function for binding the conductive substrate 10 during papermaking. Therefore, a predetermined amount of the disappearing material 20 can be secured, and by using the predetermined amount of the disappearing material 20, it is possible to form a strength that can withstand continuous paper making by strengthening the connection of the conductive base material 10.
Thus, even when a predetermined amount of the disappearing material 20 is used, the permeability of moisture and gas can be increased, and continuous paper making is easily possible by blending the predetermined amount of the disappearing material 20, whereby the gas diffusion layer substrate 1 Thus, it is possible to achieve both strength and moisture and gas permeability, and to obtain a high-quality gas diffusion layer substrate 1 with high productivity and low cost.

  Furthermore, moisture and gas permeability can be increased without reducing the vanishing material 20, a predetermined amount of the vanishing material 20 can be secured, and the voids of the vanishing material 20 are resin carbide derived from the resin 30. Therefore, it is easy to adjust the porosity and pore volume (pore diameter) depending on the blending amount and size of the vanishing material 20, and the gas diffusion layer substrate 1 Control of moisture and gas permeability is easily possible. Therefore, it is possible to easily adjust moderate permeability according to the use of fuel cell (use conditions such as operating conditions), type (component materials, etc.), etc. Adjustment of the water content) and the adjustment of the ptron conductivity can be easily performed, and the output and the improvement of the fuel cell can be easily adjusted. In particular, the combination of a large amount of the disappearing material 20 can increase the bond of the conductive base material 10 to increase the strength, and the porosity formed by the disappearance of the disappearing material 20 can be increased. Is prevented from being clogged or buried by the resin carbide derived from the resin 30, so that the void volume can be increased, so that high permeability of moisture and gas can be obtained, and flooding when applied to a fuel cell. It becomes advantageous for suppression of. In addition, as described above, adjustment of the blending amount and size of the disappearing material 20 makes it easy to control the moisture and gas permeability of the gas diffusion layer base material 1, so that it is possible to cope with dry-up. is there.

  Further, before the resin 30 is impregnated in the resin impregnation step (step S30), the resin 30 is removed from the paper making base material 40 in the disappearance step (step S20). Many will adhere to. Therefore, it is possible to easily control the characteristics such as the thickness and strength of the gas diffusion layer base material 1 by the blending amount of the resin 30 and the like, which can contribute to the adjustment and improvement of the output of the fuel cell.

Further, before the resin 30 is impregnated in the resin impregnation step (step S30), the lost material 20 in the paper making base material 40 of the disappearance step (step S20) is disappeared and the disappearance trace becomes a hole, whereby the resin The impregnation efficiency of the resin 30 in the impregnation process (step S30) is good, and it is possible to uniformly impregnate the papermaking substrate 40, which is an aggregate of the conductive substrate 10, and the papermaking substrate with a small amount of resin. It is possible to uniformly include the inside of 40, and cost reduction can be achieved. Further, since the disappearing material 20 does not exist in the papermaking base material 40 impregnated with the resin 30, the resin 30 is uniformly distributed in the papermaking base material 40, and after carbonization, the resin carbide derived from the resin 30 becomes a gas diffusion layer base. The material 1 is evenly distributed.
Therefore, the gas diffusion layer base material 1 with high homogeneity can be obtained, and the conductivity by the conductive path of the resin carbide derived from the phenol resin or the like, and the binding property of the conductive base material 10 by the resin carbide are made uniform. Can be planned. Further, the strength of the gas diffusion layer base material 1 is improved by increasing the binding property of the conductive base material 10, and further, the conductive base material that causes a short circuit by being stuck in the electrolyte membrane when applied to a fuel cell. 10 can be prevented from falling off and peeling off. In addition, since the distribution of the resin 30 is uniform, the surface smoothness can be increased, and when applied to a fuel cell, the contact area with the catalyst layer can be improved and the contact resistance can be reduced. In addition, when the surface smoothness is high, it is possible to prevent the excessive water generated by the humidified gas or the reaction from accumulating at the bonding interface of the surrounding layers such as the catalyst layer, thereby suppressing flooding.

And the situation where the void | clearance void | hole of the vanishing material 20 is filled up with the resin carbide is avoided, the resin carbide derived from the resin 30 is uniformly distributed in the gas diffusion layer base material 1, and further, the predetermined amount of the vanishing material 20 is obtained. As a result, the bonding of the conductive base material 10 is enhanced at the paper making stage to prevent the conductive base material 10 from dropping or peeling off, so that the distribution of pores is uniform and uniform.
As described above, according to the gas diffusion layer substrate 1 of the present embodiment, the pore volume and the porosity are increased, and the distribution of the pores is uniform. The amount of diffusion of the reaction gas that permeates through the layer and diffuses into the reaction part becomes uniform. As a result, the contact efficiency between the catalyst and the reaction gas is improved, and the battery performance can be improved.
If the vanishing material 20 is in a fibrous form, the voids that are vanished traces basically have a shape corresponding to the carrying form of the vanishing material 20, and are continuous holes (gas diffusion passages) with good moisture and gas permeability. , A water flow path).

  Furthermore, according to the gas diffusion layer base material 1 of the present embodiment, in the drying / heating step (step S40) and the carbonization / graphitization step (step S50), the lost material 20 is lost and voids are present in the disappeared trace. Since the papermaking substrate 40 having the above structure is heated, the gas resulting from the decomposition of the resin 30 and the condensed water generated when the resin 30 is cured are easily removed from the voids of the disappearance trace and easily discharged to the outside. Thus, deformation of the papermaking substrate 40 due to heating, generation of cracks, and the like are prevented. In addition, since the gas easily escapes in this manner, there is less possibility that the gas or the like accumulates even if the heating rate of heating is increased and the papermaking substrate 40 is deformed or cracked. Therefore, productivity can be increased.

  In addition, in the conventional technique, since the resin 30 adheres to and is adsorbed to the disappearing material 20, the resin 30 that has adhered to and adsorbed to the disappearing material 20 that has disappeared in the carbonization / graphitization step becomes a resin carbide after carbonization. In this embodiment, since the resin 30 does not adhere to or adsorb to the disappearing material 20, the resin carbide is prevented from being peeled off, and the gas diffusion layer substrate 1 has high conductivity. Sex is obtained.

Further, when the papermaking substrate 40 containing the disappearing material 20 is dried and heat-treated after impregnation with a conventional technique, the coefficient of thermal expansion (thermal contraction) by which the disappearing material 20 is decomposed at a low temperature is large. For this reason, the papermaking substrate 40 formed into a sheet may be deformed (swelled or the like) during drying and heat treatment. By reducing the rate of temperature increase, deformation can be prevented, but it takes a lot of drying time.
On the other hand, in the present embodiment, the disappearance material 20 disappears before impregnation with the resin 30, so that there is no deformation at the time of drying / heating treatment due to the disappearance material 20, thereby improving the drying / heating treatment efficiency. It is possible to reduce the cost during drying and heat treatment.

  Further, in the present embodiment, as described above, even if a predetermined amount of the disappearing material 20 is secured, the permeability of moisture and gas can be increased, and a long papermaking substrate 40 can be easily formed by continuous papermaking. The paper-making substrate 40 can be wound up, and handling properties and handling properties are high, and the gas diffusion layer substrate 1 can be obtained with high productivity and low cost.

The gas diffusion layer base material 1 of the present embodiment thus obtained can be optimally used as an electrode base material for a gas diffusion layer that forms an electrode of a solid polymer electrolyte fuel cell used in an automobile or the like.
It can also be used for applications such as electromagnetic shielding materials, conductive sheets, carbonaceous cushion materials, and furnace wall heat insulating materials for high-temperature vacuum furnaces.

  Note that the gas diffusion layer base material 1 that has been carbonized by heating and baking treatment may be applied as it is to the electrode for the gas diffusion layer, or may be subjected to water repellent treatment by impregnation with a fluorine-based resin or the like. In some cases, a coating layer (microporous layer) is formed on the surface by applying a coating solution for forming (microporous layer), and then applied to the gas diffusion layer electrode.

  Next, the gas diffusion layer substrate 1 according to the embodiment of the present invention will be described with reference to examples.

[Example 1]
The gas diffusion layer substrate 1 according to Example 1 is a carbon fiber (short fiber; average fiber diameter of 0.1 to 50 μm) as the conductive substrate 10 in the blending amount (part by weight) shown in Table 1 below. , Average fiber length of 0.01 to 50 mm) and fibrillated pulp (wood-based, cellulose-based) as the disappearing material 20 are mixed in water as a dispersion medium and beaten in water using an appropriate papermaking reagent. As a result, the carbon fibers and the pulp were uniformly dispersed in water. In addition, water was 98.0-99.9 weight part with respect to a total of 100 weight part of carbon fiber and a pulp. Subsequently, the resulting carbon fiber / pulp / water mixture was subjected to papermaking using a mesh member, and the papermaking step (step S10) was performed.
Papermaking is contained in the mixture by supplying the mixture to the upper surface of a mesh member (stainless steel (SUS316, 65-80 mesh) or plastic) and performing vacuum dehydration with a vacuum dehydrator placed at the bottom of the mesh member. The liquid component (water as a dispersion medium) was separated from the solid component (carbon fiber and pulp), and the solid component (carbon fiber and pulp) was deposited on the upper surface of the mesh member.
Thus, a sheet-like papermaking substrate 40 having a basis weight (weighing) of 45 to 60 g / cm ² and an average thickness of 250 to 300 μm was obtained. The papermaking substrate 40 thus obtained is a sheet-like aggregate of carbon fibers and pulp.
In Example 1, since a predetermined amount of fibrillated pulp was used as the disappearing material 20, it had strength and shape-retaining properties that could withstand continuous paper making by a wet continuous paper making device, and therefore continuous using a wet continuous paper making device. A long papermaking substrate 40 sheet was produced by papermaking.

Next, the vanishing process (step S20) which lose | disappears a pulp by heating the sheet-like paper-making base material 40 formed by making paper together in this way at 400 degreeC for 1 hour was implemented. In Example 1, the paper base 40 sheet was heat-treated with a heating roll incorporating a heater in a batch type heating furnace.
In addition, by making a paper using a predetermined amount of the fibrillated pulp as the vanishing material 20 together with the carbon fiber, the carbon fiber is strongly bound, and even after the fibrillated pulp is lost in the disappearing step (step S20), The shape of 40 was maintained, there was no dropping or peeling of the carbon fiber, and handling and handling were good.

  Subsequently, the sheet-like papermaking substrate 40 from which the pulp has disappeared is immersed in a phenol resin solution (dispersion) to impregnate the sheet-like papermaking substrate 40 from which the pulp has disappeared with the phenol resin as the resin 30. A resin impregnation step (step S30) was performed. The amount (parts by weight) of phenol resin (solid content) at this time is as shown in Table 1 below.

Thereafter, a drying / heating process (step S40) is performed in which the sheet-shaped paper-making substrate 40 impregnated with the phenolic resin is dried and heated in the hot air oven at 180 ° C. for 5 minutes in the air to dry the paper-making substrate 40. Also, the resin 30 in the papermaking substrate 40 was cured.
Then, the carbonization and graphitization process (step S50) which heats by a heating-firing furnace at 2000-2500 degreeC for 1 hour in nitrogen gas atmosphere, and carbonizes a phenol resin was implemented.
In Example 1, heating and firing were performed in a batch heating furnace in which nitrogen gas was circulated.
Thus, the gas diffusion layer base material 1 according to Example 1 was obtained.

[Comparative Example 1]
Moreover, in order to compare the characteristics (gas permeability described later) of the gas diffusion layer substrate 1 according to Example 1, a gas diffusion layer substrate according to a comparative example was also produced.
In Comparative Example 1, the same blending contents (materials) and blending amounts as in Example 1 were prepared, but the disappearance process (Step S20) in Example 1 was omitted, and the resin impregnation was performed immediately after the paper making process (Step S10). The process (Step S30) was performed, and subsequently the drying / heating process (Step 40) and the carbonization / graphitization process (Step S50) were performed to obtain the gas diffusion layer base material according to Comparative Example 1. Each paper making process (step S10), resin impregnation process (step S30), drying / heating process (step 40), and carbonization / graphitization process (step S50) were performed under the same conditions as in Example 1. In Comparative Example 1, as in Example 1, continuous paper making was possible in the paper making process (step S10).

[Comparative Example 2]
Also in Comparative Example 2, it was manufactured in the same manufacturing process as Comparative Example 1. That is, the disappearance step (step S20) in Example 1 is omitted, and the resin impregnation step (step S30) is performed immediately after the paper making step (step S10), and then the drying / heating step (step 40) and carbonization are performed. -The graphitization process (step S50) was implemented. In Comparative Example 2, the same blending material as in Example 1 and Comparative Example 1 is used, but as shown in Table 1 below, the amount of pulp as the disappearing material 20 is 4 minutes as compared with Example 1 and Comparative Example 1. The gas diffusion layer substrate according to Comparative Example 2 was obtained by reducing to 1.
In Comparative Example 2, as in Example 1, continuous paper making was possible in the paper making process (step S10).

  In such Comparative Example 1 and Comparative Example 2, the disappearing material 20 is present in the papermaking substrate 40 at the stage of impregnation with the phenol resin, and the disappearing material 20 is disappeared in the carbonization / graphitization step (step S50). Will be.

  In addition, the gas diffusion layer base materials according to Example 1 and Comparative Examples 1 and 2 thus obtained were porous with pores formed as shown in the microscope photographs of FIGS. 2 to 4. Yes, the carbon fiber was bound by the resin carbide derived from the phenol resin, and the resin carbide in the gas diffusion layer substrate was 20% by mass (the residual carbon ratio of the phenol resin was 70%). The average thickness of the gas diffusion layer base material according to Example 1 and Comparative Examples 1 and 2 was 150 to 250 μm.

  Here, the gas diffusion layer base material of Example 1 and Comparative Examples 1 and 2 thus obtained was subjected to a test for examining gas permeability (ease of gas escape).

Regarding the gas permeability of the gas diffusion layer base material, in a state where the gas diffusion layer base material is fixed, dry nitrogen is allowed to flow perpendicularly to the surface of the gas diffusion layer base material, ), And the pressure difference was measured.
Specifically, as shown in FIG. 5, one side in the thickness direction of one test piece (gas diffusion layer base material) is a pressure chamber, and the other side in the thickness direction of the test piece is an open chamber. The test piece was set horizontally on the test apparatus. Then, nitrogen gas was supplied as a test gas to the pressure chamber at a flow rate of 10 L / min, and the pressure difference between the pressure chamber and the open chamber was measured when the pressure change after a predetermined time elapsed. It can be said that the smaller the value of the differential pressure (MPa), the higher the gas permeability. In Example 1 and Comparative Example 1, the basis weight (basis weight) of the gas diffusion layer base material 1 through which gas was permeated was 30 g / cm ² (carbon fiber 24 g / cm ² , resin carbide 6 g / cm ² ). is there.

  Table 1 shows the amounts (parts by weight) of materials used for the production of the gas diffusion layer base materials according to Example 1, Comparative Example 1, and Comparative Example 2, production conditions, and measurement results of gas permeability. .

As shown in Table 1, the differential pressure between the front and back in the thickness direction of the gas diffusion layer base material in the test for evaluating gas permeability is highest in the gas diffusion layer base material according to Comparative Example 1, at 0.55 MPa. Yes, the gas permeability was the smallest.
Moreover, although it implements in the same manufacturing process as Comparative Example 1, in Comparative Example 2 in which the amount of the pulp as the vanishing material 20 is less than that in Comparative Example 1, the differential pressure is smaller than that in Comparative Example 1, but the value is It was 0.10 MPa.

  In Comparative Example 2, the resin amount of the phenol resin is the same as in Comparative Example 1, but the disappearance trace formed by the disappearance of the pulp by reducing the amount of the pulp 20 as the disappearing material 20. Despite the decrease in pores, the differential pressure in Comparative Example 2 was smaller than that in Comparative Example 1 with a large amount of pulp. However, the strength of the gas diffusion layer substrate was lower than that of Comparative Example 1 by reducing the amount of pulp as the disappearing material 20.

On the other hand, according to the gas diffusion layer substrate 1 according to Example 1, the gas permeability was highest at a differential pressure of 0.02 MPa and a very low value.
This is because, in Comparative Example 1 and Comparative Example 2, pulp is present on the papermaking substrate 40 at the stage of impregnation with the phenolic resin. A lot of carbides remained, and the disappearance trace of the pulp was filled more with the phenol resin 30, whereas in Example 1, at the stage of impregnation with the phenol resin, the pulp was not present in the papermaking substrate 40, This is because the phenol resin is uniformly distributed without adhering to and adsorbing to the pulp, so that the carbonized phenol resin does not obstruct gas permeability by filling many disappearance traces of the pulp.

In particular, in Example 1, although the amount of phenol resin, carbon fiber, and pulp used were the same as those in Comparative Example 1, the gas diffusibility was significantly improved as compared with Comparative Example 1.
Moreover, although the amount of phenol resin and the amount of carbon fiber are the same as Example 1, Example 1 shows much higher gas diffusibility than Comparative Example 2 which reduced pulp amount to 1/4, The strength was high enough to enable continuous paper making at the paper making stage.
That is, according to the gas diffusion layer substrate 1 of Example 1, the gas diffusibility was enhanced while maintaining the strength.

By the way, according to an experimental study by the present inventor, when making paper, the strength (tensile strength) that can withstand continuous paper making when the carbon fiber 10 is 100 parts by weight and the pulp 20 is less than 40 parts by weight. It has been confirmed that continuous papermaking becomes difficult. Therefore, preferably, if the blending amount of the pulp 20 is 40 parts by weight or more, it is possible to ensure sufficient strength to withstand continuous paper making, continuous paper making is easy, and productivity can be increased.
And if the pulp 20 is in the range of 40 parts by weight to 300 parts by weight with respect to 100 parts by weight of the carbon fiber 10, the paper making base 40 is formed by continuous paper making of the carbon fiber 10 and the pulp 20 in the paper making process. Therefore, productivity can be increased and costs can be reduced. Moreover, the intensity | strength and electroconductivity by the carbon fiber 10 are ensured, and the intensity | strength of the gas diffusion layer base material 1 obtained becomes high.

In addition, from the microscope photographs of FIGS. 2 to 4, in Comparative Example 1 (see FIG. 3), a large amount of phenolic resin adhered and adsorbed on the pulp, so the distribution of resin carbide is uneven and dense, resulting in voids. It can be confirmed that the distribution of pores and the pore volume are also sparse. Moreover, in the comparative example 2 (refer FIG. 4), it can confirm that the distribution of carbon fiber is coarse because there was little pulp amount.
In contrast, in Example 1 (see FIG. 2), it can be confirmed that the distribution of the resin carbide is uniform, the carbon fibers are densely distributed, and the distribution of the pores is uniform.

Here, according to the inventor's experimental research, when the differential pressure is smaller than 0.01, the gas permeability becomes too high, so that the fuel cell electrode for automobiles that require high power density is used. When used, for example, the drying of the polymer membrane is likely to proceed under high temperature operating conditions, which may reduce battery performance. On the other hand, if the differential pressure is greater than 0.3, the gas permeability is low. In addition, it has been confirmed that the output improvement effect is small in a fuel cell for automobiles that requires a high output density.
Therefore, when the differential pressure is in the range of 0.01 to 0.3 MPa, a high output can be stably obtained in a fuel cell for an automobile that requires a power density.
And by the present inventor's experimental research, the papermaking base material 40 formed by papermaking together the carbon fiber as the conductive base material 10 and the pulp as the disappearance material 20 is heated at a predetermined temperature to make the papermaking base material 40. The pulp 20 inside disappeared, the pulp 20 disappeared, and the papermaking substrate 40 made of an aggregate of carbon fibers 10 was impregnated with a carbonizable phenolic resin as the resin 30, and the phenolic resin 30 was impregnated. The paper making base 40 is dried and heated at a predetermined temperature, and further heated and fired at a predetermined temperature in a non-acidic atmosphere to carbonize and graphitize the phenol resin in the paper making base 40, thereby obtaining a basis weight of 30 g. / in cm ² under the conditions, both sides of the differential pressure of the gas diffusion layer base material 1 when flowed through the dry nitrogen gas from the flow rate 10L / min in a gas diffusion layer base material 1 in the thickness direction of the one surface is zero. 01-0.3 It has been confirmed that the gas diffusion layer base material 1 within the range of MPa is obtained. In applications where high reaction activity is required in the fuel cell, the differential pressure is preferably in the range of 0.01 to 0.2 MPa, more preferably 0.01 to 0.08 MPa. Within range.

  Thus, the manufacturing method of the gas diffusion layer base material 1 according to Example 1 has a binder function for linking the carbon fiber as the conductive base material 10 and the conductive base material 10 and can be lost by heating. Paper making process (step S10) for making paper together with pulp as the disappearing material 20 to form the paper making base material 40, and a disappearing process for heating the paper making base material 40 to eliminate the pulp 20 in the paper making base material 40 (Step S20), a resin impregnation step (Step S30) for impregnating the papermaking substrate 40 made of an aggregate of carbon fibers 10 from which the pulp 20 has disappeared with a phenol resin as the carbon precursor resin 30, and drying and heating After drying and heating the papermaking substrate 40 impregnated with the phenol resin 30 in the step (step S40), the papermaking substrate 40 is heated in a non-oxidizing atmosphere to impregnate the papermaking substrate 40 Those having a carbide-graphitization step of carbonization and graphitization fat 30 (step 50).

  And the gas diffusion layer base material 1 of Example 1 consists of the accumulation body of the carbon fiber 10 after the pulp 20 in the papermaking base material 40 formed by making paper together with the carbon fiber 10 and the pulp 20 disappears. Since the paper making base material 40 is impregnated with the phenol resin 30 and the phenol resin 30 is carbonized by predetermined heating and baking, the carbon fibers 10 are bound by the carbide of the phenol resin 30, and the loss of the pulp 20 causes a predetermined amount. Of the gas diffusion layer substrate 1 when dry nitrogen gas is allowed to flow from one surface in the thickness direction of the gas diffusion layer substrate 1 at a flow rate of 10 L / min. The pressure difference between the front and back sides is in the range of 0.01 to 0.3 MPa.

  Thus, before impregnating the paper making base material 40 with the phenol resin 30 in the resin impregnation step (step S30), the pulp 20 in the paper making base material 40 is lost, so that the phenol resin 30 adheres to and adsorbs to the pulp 20. By doing so, the situation in which the carbide of the phenol resin 30 remains in the disappearance trace of the pulp 20 to block or fill the disappearance trace is avoided, and a predetermined pore volume can be secured in the disappearance trace of the pulp 20. Therefore, the moisture and gas permeability of the gas diffusion layer substrate 1 is improved.

Then, by impregnating the phenolic resin 30 with the papermaking substrate 40 from which the pulp 20 has disappeared, the phenolic resin 30 can be evenly distributed in the carbon fibers 10, and a predetermined pore volume is secured in the pulp mark. As a result, the permeability of moisture and gas can be improved without reducing the use of the pulp 20 that causes a decrease in strength, and a sufficient amount of the pulp 20 can be secured. Therefore, when paper is made together with carbon fibers by using a predetermined amount of pulp 20, a suitable strength can be ensured, so that continuous paper making is also possible. Furthermore, even if the pulp 20 disappears, the strength and shape retention of the papermaking substrate 40, which is an aggregate of the carbon fibers 10, are ensured, and the subsequent handling properties are also good.
In this way, the gas diffusion layer substrate 1 and the method for producing the same can be obtained with improved productivity of moisture and gas, high strength, and high productivity.

  In particular, in Example 1, the conductive base material 10 is made of carbon fiber, the disappearing material 20 is made of pulp, and the resin 30 is made of phenol resin. In addition, the pulp 20 easily disappears by heating under a low temperature condition, and there is almost no residue. The void volume and porosity of the disappeared trace can be increased, and the moisture and gas permeability is high. Can be obtained. Furthermore, the phenol resin 30 has a high carbonization rate, and the carbide of the phenol resin 30 has a strong binding force with the carbon fiber 10, whereby the conductivity and strength of the gas diffusion layer substrate 1 can be increased.

  In the above embodiment, carbon fibers are used for the conductive base material 10; however, when the present invention is carried out, carbon black (for example, Fourness Black, Acetylene Black, Lamp Black, Thermal Black, etc.) is appropriately used. It is also possible to use conductive particles such as graphite and carbon nanotubes, thereby improving the contact property of the carbon fibers and improving the conductivity. In particular, since pulp is used as the disappearing material 20, the conductive particles adhere to the carbon fibers 10 and the pulp 20 even when paper making, and the rate of transfer to the papermaking body is also high.

  Moreover, in the said embodiment, although the shape of the papermaking base material 40 was formed in the thin sheet form, when implementing this invention, it is also possible to form in the plate shape etc. which are thick and difficult to wind up It is.

DESCRIPTION OF SYMBOLS 1 Gas diffusion layer base material 10 Conductive base material 20 Dissipating material 30 Resin (carbon precursor resin)
40 Papermaking substrate

Claims (3)

A papermaking step of forming a papermaking base material by making a paper together with a conductive base material, a binder function for binding the conductive base material, and a disappearing material that can be lost by heating;
A disappearing step of heating the papermaking substrate to eliminate the disappearing material in the papermaking substrate;
A resin impregnation step of impregnating a carbon precursor resin into the papermaking base material comprising the aggregate of the conductive base material after the disappearance material has disappeared;
A carbonization / graphitization step of carbonizing and graphitizing the carbon precursor resin by drying and heating the paper base material impregnated with the carbon precursor resin, followed by heating and firing in a non-oxidizing atmosphere. A method for producing a gas diffusion layer base material.   The method for producing a gas diffusion layer substrate according to claim 1, wherein the conductive substrate is made of carbon fiber, the disappearing material is made of pulp, and the carbon precursor resin is made of a phenol resin. Comprising a conductive base material and a resin carbide that binds the conductive base material, and is a porous gas diffusion layer base material in which predetermined pores are formed,
The gas diffusion when dry nitrogen gas is allowed to flow at a flow rate of 10 L / min to one surface in the thickness direction of the gas diffusion layer base material with respect to the gas diffusion layer base material having a basis weight of 30 g / cm ² A gas diffusion layer base material, wherein the pressure difference between the front and back surfaces of the layer base material is within a range of 0.01 to 0.3 MPa.