JP4559767B2 - Carbon electrode substrate manufacturing method - Google Patents

Description

  The present invention relates to a carbon electrode base material having high strength and flexibility and used for a fuel cell, particularly a gas diffusion layer of a polymer electrolyte fuel cell, and a method for producing the same.

  The carbon electrode base material is not only conductive and gas permeable, but also excellent in corrosion resistance, mechanical strength and flexibility, so it can be used for gas and electrical applications such as gas diffusion layers for polymer electrolyte fuel cells. Widely used for those requiring transmission ability. However, for example, when used as a gas diffusion layer for a polymer electrolyte fuel cell, there is a problem that the diffusion of the reaction gas is gradually inhibited and the pores of the gas diffusion layer are blocked (flooding) in some cases. . This may be because the water generated by the electrochemical reaction is not efficiently discharged and the water stays on the carbon electrode substrate. When such flooding occurs, a rapid decrease in output is observed particularly in a high current density region. Accordingly, a carbon electrode substrate used for a polymer electrolyte fuel cell is particularly required to have a water management function in which water does not easily stay.

  Moreover, in patent document 1, the carbon electrode base material from which the area of a pore becomes large toward an other end is manufactured. However, the production of the carbon electrode base material is performed by batch production, and the degree of freedom of processing when assembling as a fuel cell is reduced as compared with the carbon electrode base material continuously wound in a roll shape. Although it is possible in principle to make the carbon electrode substrate continuously wound into a roll shape, the process becomes complicated and leads to an increase in cost.

Further, in Patent Document 2, an electron conduction path is a portion where carbon fibers are dense (for example, a portion where carbon fibers overlap in a carbon cloth), and a gas permeation route is a portion where carbon fibers are not overlapped (for example, a portion where carbon fibers are not overlapping in carbon cloth) The carbon electrode base material is manufactured so that a portion where no carbon fiber exists (for example, a portion where carbon fiber does not exist in the carbon cloth) serves as a generated water discharge path. However, in this case, the thickness of the carbon electrode substrate is uneven due to the overlap of the carbon fibers, so that when assembled as a fuel cell, the contact resistance between the adjacent electrolyte membrane and the separator may increase.
JP 2002-319411 A JP 2003-142110 A

  The present invention can continuously roll up the carbon electrode substrate without damaging the excellent conductivity, gas permeability, mechanical strength and flexibility of the carbon electrode substrate, and has an excellent water management function. The object is to provide a carbon electrode substrate and a method for producing the same.

The gist of the present invention is (a) a process of making carbon short fibers into carbon fiber paper in a state where a perforated plate in which holes are formed in a flat plate is installed on the lower side of a mesh plate used for paper making;
(B) impregnating the carbon fiber paper with a thermosetting resin to obtain a resin-impregnated carbon fiber paper;
(C) heat-pressing the resin-impregnated carbon fiber paper to obtain a resin-cured carbon fiber paper;
(D) A method for producing a carbon electrode substrate, comprising: baking the resin-cured carbon fiber paper at a temperature of 1200 ° C. or higher in a nitrogen atmosphere to form a carbon electrode substrate.

The pore diameter of the porous plate is 4 to 10 mm, and the pitch distance of the porous plate is 6 to 12 mm;
In the step (a), using a binder up to 5% by mass with respect to the short carbon fibers,
Carrying out each of the steps (b) to (d) continuously,
A continuous belt device comprising a heating zone capable of preheating the resin-impregnated carbon fiber paper and a curing zone capable of curing the thermosetting resin while pressing the resin-impregnated carbon fiber paper in the step (c). Furthermore, the temperature of the heating zone is 120 to 300 ° C., the passage time of the heating zone is 1 to 6 minutes, and the temperature of the curing zone is 250 to 400 ° C. (however, a temperature higher than the temperature of the heating zone) The pressing pressure in the curing zone is 1 to 20 MPa,
It is preferable that the belt speed in the continuous belt device is 0.1 to 6.0 m / min.

  According to the present invention, the carbon electrode base material has excellent conductivity, gas permeability, mechanical strength and flexibility, and can be continuously wound into a roll, and has a water management function. It is possible to provide an excellent carbon electrode substrate and a method for producing the same.

  The present invention is described in detail below.

  The carbon electrode base material can be used for electrodes of battery members such as primary batteries, secondary batteries, fuel cells, electric double layer capacitors, capacitors, etc., and is not corroded by acid, and conducts and stores electricity. It is something that can be done. The carbon electrode base material in the present invention is a carbon electrode base material composed of carbon short fibers and a carbonized resin, and in any one direction in the plane direction, a portion having a high carbon short fiber content, and carbon short fibers The part which does not contain or the content rate of a short carbon fiber is low appears repeatedly. In any one direction in the plane direction, it is preferable that a portion having a high carbon short fiber content and a portion not containing the carbon short fiber or a portion having a low carbon short fiber content appear regularly and repeatedly. The carbon electrode substrate of the present invention is particularly suitable as a carbon electrode substrate for a polymer electrolyte fuel cell.

  In the carbon electrode substrate of the present invention, gas easily passes through a portion where carbon short fibers are relatively small, and water easily passes through a portion where carbon short fibers are relatively large. That is, for example, when used in a polymer electrolyte fuel cell, fuel gas is supplied through a portion with relatively short carbon fibers, and generated water is discharged through a portion with relatively short carbon fibers. . Therefore, water does not easily stay in the carbon electrode base material, and when used as, for example, a gas diffusion layer for a polymer electrolyte fuel cell, a rapid output drop is less likely to occur particularly in a high current density region. The expression of such a function is considered to be affected by the difference in surface tension, the likelihood of capillary action, etc., depending on the content of short carbon fibers.

  The carbon short fiber is obtained by cutting a carbon fiber yarn or a carbon fiber tow short. Here, a carbon fiber having a length of 100 mm or less is a short carbon fiber. The types of carbon fibers include polyacrylonitrile, pitch, phenol, and graphite. However, since the carbon electrode base material has higher bending strength and tensile strength, polyacrylonitrile-based carbon fibers have been cut. It is preferable to use short carbon fibers. Further, it is more preferable that 70% by mass or more of the short carbon fibers to be used are polyacrylonyl carbon short fibers.

  A polyacrylonitrile-based carbon fiber is a spinning process for producing a polyacrylonitrile-based fiber that is a precursor (precursor), and a flameproofing process in which the fiber is heated and fired in an air atmosphere at 200 to 400 ° C. to convert it into an oxidized fiber. , A fiber obtained through a carbonization step of carbonization by heating to 300 to 2500 ° C. in an inert atmosphere such as nitrogen, argon, helium, etc., which is generally used as a composite material reinforcing fiber Can be used.

  The short carbon fibers used in the present invention preferably have a minimum fiber diameter of 5 μm or less and a fiber length of 15 mm or less. By including short carbon fibers having a fiber diameter of 5 μm or less, the flexibility of the carbon electrode substrate is improved. The average fiber diameter of the short carbon fibers is more preferably 5 μm or less, and the maximum value of the short fiber diameter is particularly preferably 5 μm or less. The lower limit of the fiber diameter is not particularly limited, but the minimum fiber diameter is preferably 3 μm or more. In addition, the fiber diameter of the short carbon fiber was measured by a helium-neon laser (manufactured by Anritsu, trade name: SLB DIA MEASURING SYSTEM) described in JIS R-7601. The average fiber diameter was measured for 100 carbon fibers, and the average value was defined as the average fiber diameter of the carbon fibers. Further, it is preferable to set the fiber length to 15 mm or less because dispersibility in the stock liquid during paper making becomes good and more uniform paper can be produced. More preferably, it is 9 mm or less. The lower limit of the fiber length is not particularly limited, but is preferably 3 mm or more.

  The carbonized resin that is a constituent component of the carbon electrode substrate of the present invention is obtained by carbonizing a resin. The resin to be carbonized may be a thermoplastic resin or a thermosetting resin. A thermosetting resin is preferred because it does not liquefy when the temperature is raised. As a thermosetting resin, a phenol resin, an epoxy resin, a melamine resin, a urea resin etc. can be used, for example. Phenol resin is preferred because of high carbonization efficiency. The carbonization treatment can be performed, for example, by a firing process described later.

  In the carbon electrode substrate of the present invention, the carbonized resin is preferably contained in an amount of 20 to 70% by mass with respect to the short carbon fibers. The intensity | strength of a carbon electrode base material becomes higher because a carbonized resin ratio shall be 20 mass% or more. Moreover, the porosity of a carbon electrode base material becomes higher by setting it as 70 mass% or less, and gas-permeation performance improves more. More preferably, it is 30-50 mass%.

The carbon electrode substrate of the present invention preferably has a thickness of 0.3 mm or less in view of high flexibility and easy handling. More preferably, it is 0.25 mm or less. Moreover, it is preferable that it is 0.05 mm or more from a viewpoint of intensity | strength, and it is more preferable that it is 0.1 mm or more. Moreover, as a carbon electrode base material of this invention, it is preferable that the penetration resistance of thickness direction is 10 m (ohm) * cm < ² > or less from a viewpoint of the cell performance when it integrates as a fuel cell member. More preferably, it is 8 mΩ · cm ² or less. The lower limit is not particularly limited, but is usually 3 mΩ · cm ² or more.

  As a carbon electrode base material of this invention, what has a full length of 20 m or more is preferable. Moreover, it is preferable to provide in the state wound up by roll shape. This is because productivity can be improved due to the continuum such as the size and shape can be processed freely. Although there is no restriction | limiting in particular about the upper limit of length, From a viewpoint of workability | operativity in the state wound up by roll shape, it is preferable that it is 500 m or less.

The carbon electrode substrate as described above is
(A) In a state where a perforated plate is installed on the lower side of the net used for paper making, paper short fibers are made into carbon fiber paper;
(B) impregnating the carbon fiber paper with a thermosetting resin to obtain a resin-impregnated carbon fiber paper;
(C) heat-pressing the resin-impregnated carbon fiber paper to obtain a resin-cured carbon fiber paper;
(D) The resin-cured carbon fiber paper can be suitably produced by a method comprising baking the resin-cured carbon fiber paper at a temperature of 1200 ° C. or higher to form a carbon electrode substrate. The method will be described below.

  First, carbon short paper is made to produce carbon fiber paper. At this time, carbon short fibers are made with a perforated plate installed below the mesh plate used for paper making. In this way, the portion of the perforated plate that has pores has a relatively large amount of short carbon fibers, while the portion of the perforated plate that has no holes has a relatively small amount of short carbon fibers, so The carbon fiber paper changes according to the arrangement. That is, in any one direction in the plane direction, a carbon fiber paper in which a portion having a high carbon short fiber density and a portion not containing carbon short fibers or a portion having a low carbon short fiber density appear repeatedly. Since the distribution state of the short carbon fiber in the short carbon fiber paper is maintained in the subsequent process, the carbon electrode base material finally obtained has a carbon short fiber content in any one direction in the plane direction. And a portion that does not contain carbon short fibers or has a low content of carbon short fibers repeatedly appear.

  More specifically, the liquid containing short carbon fibers is separated into short carbon fibers and moisture on the mesh plate, and only the short carbon fibers remain on the mesh plate (see FIG. 4A). At this time, by disposing the perforated plate below the mesh plate, a portion through which moisture actively passes (portion of the hole in the perforated plate) and a portion other than that (portion of the perforated plate without the hole) are formed. As a result, a relatively large amount of short carbon fibers gathers in a portion where moisture actively passes, and a relatively small amount of short carbon fibers in a portion where moisture does not pass (see FIG. 4B).

  As the porous plate, a porous plate having a hole diameter of 4 to 10 mm and a pitch distance of 6 to 12 mm is preferable. The distance between pitches here is a distance connecting the center points of the holes. Further, by using a mesh plate in which the hole part is partially blocked, it is possible to create the same situation as when the mesh plate and the porous plate are used in combination. The holes are preferably arranged regularly.

  When making short carbon fibers, it is preferable to use a binder (binder) for the purpose of fixing the short carbon fibers together. If the amount is too large, the electrical resistance of the electrode substrate obtained by firing becomes high, and therefore it is more preferable to use a binder in an amount of up to 5% by mass based on the short carbon fibers. Thereby, it is possible to maintain the strength of the obtained carbon fiber paper, and to prevent the short carbon fibers from peeling and dropping from the carbon fiber paper during the production and the change in the orientation of the short carbon fibers. As the binder, a high molecular compound is preferable. For example, polyvinyl alcohol, or an acrylonitrile-based polymer pulp or short fiber can be used. Moreover, there is no restriction | limiting in particular as a state of a binder, Any, fibrous form, pellet form, powder form, etc. may be sufficient.

  Papermaking of short carbon fibers can be carried out either batchwise or continuously, but the continuous method is preferred from the viewpoint of productivity. In the case of the continuous type, it is preferable that the perforated plate is moved while moving at the same speed as the mesh plate. As a method for continuously making short carbon fibers, a technique similar to a known method such as a circular net type, a long net type, or a short net type for continuously making paper from fibers such as pulp may be applied. Since the circular net type requires a considerable amount of binder, the long net type and the short net type are preferable from the viewpoint of manufacturing cost.

The average mass per unit area of the carbon fiber paper obtained by the papermaking is preferably ^{15g / m 2 ~40g / m 2} .

  Next, a carbon fiber paper obtained by paper making is impregnated with a thermosetting resin to obtain a resin-impregnated carbon fiber paper. This step can be carried out either batchwise or continuously, but is preferably continuous from the viewpoint of productivity. As a method for impregnating carbon fiber paper with a thermosetting resin, a dip-nip method using a squeezing device, a method of uniformly coating a resin on the surface of carbon fiber paper using a coater, and transferring a resin film to carbon fiber paper It can be performed by a general continuous production method such as a method. In the dip-nip method, carbon fiber paper is immersed in a mixed solution of a thermosetting resin and a solvent such as alcohol such as methanol or ethanol, and the mixed solution is uniformly applied to the entire carbon fiber paper by a squeezing device. The coating amount is adjusted by changing the roll interval of the squeezing device. When the viscosity of the mixed solution containing the thermosetting resin is relatively low, it is possible to more uniformly impregnate the thermosetting resin by using a method of coating with a coater or a method of transferring a resin film. When the viscosity is high, the dip-nip method is preferable because the thermosetting resin does not easily penetrate into the carbon fiber paper. Thus, it is necessary to employ an appropriate impregnation method depending on the viscosity of the thermosetting resin.

  Then, the obtained resin-impregnated carbon fiber paper is heated and pressed to obtain a resin-cured carbon fiber paper. This hot pressing process is an indispensable process for improving the strength and thickness accuracy of the finally obtained carbon electrode substrate, and any technique can be used as long as heat and pressure can be applied to the resin-impregnated carbon fiber paper. Applicable. For example, a method of pressing with a metal plate from both the upper and lower surfaces, a method of molding by inserting into a mold, and a method of using a continuous belt device are mentioned. This step can be carried out either batchwise or continuously, but is preferably continuous from the viewpoint of productivity. The method of hot pressing with a continuous belt device is more preferable in that it can produce a continuous carbon electrode substrate of 20 m or more and has high productivity.

  A schematic diagram of an example of a continuous belt device is shown in FIG. In the continuous belt device, a pair of metal belts 3 are arranged at the top and bottom, and the resin-impregnated carbon fiber paper 1 is passed between the belts 3 while operating.

  A continuous belt device requires both a heating device and a press device. In particular, as shown in FIG. 3, it is preferable to have a heating zone 4 capable of preheating the resin-impregnated carbon fiber paper and a curing zone 5 capable of curing the thermosetting resin while pressing the resin-impregnated carbon fiber paper. . The heating zone 4 is a zone that is set to a temperature at which the thermosetting resin becomes soft and can be effectively pressed in the curing zone 5. Even in the absence of the heating zone 4, in principle, pressing is possible, but since the carbon electrode base material is likely to be wrinkled and cracked and production stability may be lowered, the heating zone 4 is provided. It is preferable.

  In the continuous belt device as described above, it is preferable to press at a pressure of 1 to 20 MPa. The heating zone temperature is 120 to 300 ° C., the heat treatment time is 1 to 6 minutes, the curing zone temperature is 250 to 400 ° C. (but higher than the heating zone temperature), and the press pressure is 1 to 20 MPa. Is more preferable because the strength of the carbon electrode substrate is improved. If the temperature of the heating zone is too low or the heat treatment time is too short, wrinkles are likely to occur on the carbon electrode substrate. If the temperature of the heating zone is too high, the thermosetting resin may be cured before pressing. On the other hand, when the press pressure is too low, the conductivity of the carbon electrode substrate may be reduced due to insufficient contact between the short carbon fibers, and the flexibility of the carbon electrode substrate is reduced because the thickness is increased. Tend. When the press pressure is too high, there is no problem in the characteristics of the carbon electrode substrate, but an excessive press facility is required, which is not preferable in terms of cost effectiveness.

  Moreover, it is preferable that the speed of the belt 3 is 0.1-6.0 m / min from a viewpoint of manufacturing efficiency and the quality of a carbon electrode base material.

  If the resin-impregnated carbon fiber paper 1 is passed between the belts 3 as it is, the belt 3 and the resin-impregnated carbon fiber paper 1 may adhere to each other due to the oozed resin. Therefore, it is preferable to coat a release agent on the surface of the resin-impregnated carbon fiber paper 1 in contact with the belt 3 of the continuous press apparatus. As the release agent, for example, a fluorine-based resin and a silicon-based resin are preferable from the viewpoint of releasability. Alternatively, as shown in FIG. 3, it is preferable to sandwich a release agent-coated substrate 2 coated with a release agent between a belt 3 and a resin-impregnated carbon fiber paper 1 of a continuous press apparatus. As the release agent coating substrate 2, for example, paper having excellent thermal stability and mechanical strength coated with fluorine resin or silicon resin can be used, and a smooth one having a surface roughness of 1 μm or less is released. It is preferable from the viewpoint of moldability.

  A carbon electrode base material is obtained by the process of baking the obtained resin-cured carbon fiber paper at a temperature of 1200 ° C. or higher in a nitrogen atmosphere after the heating press. Nitrogen atmosphere means an atmosphere of only nitrogen, and some oxygen and other gas molecules may be mixed. As a calcination temperature, 1400-2200 degreeC is preferable from a mechanical strength and electroconductivity viewpoint of a carbon electrode base material. The furnace for firing can be used without particular limitation as long as it is a furnace that can be fired at 1200 ° C. or higher in a nitrogen atmosphere, but from the viewpoint of productivity, it is preferable to continuously fire using a continuous firing furnace.

  EXAMPLES The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the examples of the present invention. In addition, each physical-property value in an Example was measured with the following method.

1) Bending strength of carbon electrode base material It measured using the bending strength test apparatus (A and D company make, brand name: Tensilon UTM-I-2500). Specifically, using a carbon electrode substrate cut to 8 cm × 1 cm as a test piece, applying a load at a fulcrum distance of 2 cm and a strain rate of 10 mm / min, the pressure wedge when the test piece breaks The load was measured and the bending strength was obtained from the following formula.

2) Deflection of carbon electrode base material It measured using the bending strength test apparatus (A and D company make, brand name: Tensilon UTM-I-2500). Specifically, using a carbon electrode substrate cut to 8 cm × 1 cm as a test piece, a load was applied at a distance between fulcrums of 2 cm and a strain rate of 30 mm / min, and the test piece was broken from the point where the load began to be applied. The movement distance of the pressure wedge up to the time of the bending was defined as the deflection.

3) Gas permeability of carbon electrode base material Based on JIS-P8117, a Gurley densometer (manufactured by Kumagai Riki Co., Ltd.) was used, and the time required for 200 mm ³ gas (air) to pass through was measured and calculated.

4) Penetration resistance of carbon electrode base material A sample of the carbon electrode base material was sandwiched between copper plates, pressed at 1 MPa from the top and bottom of the copper plate, and measured for resistance when a current was passed at a current density of 10 mA / cm ^2. Obtained from the equation.

Penetration resistance (Ω · cm ² ) = Measured resistance value (Ω) × Sample area (cm ² ) (2)
5) Power generation characteristics of single cell stack The single cell stack was connected to FUEL CELL TEST SYSTEM (product name: SERIES 890B, manufactured by SCRIBNERASSOCIATE. INC), and a power generation characteristic test was performed.

[Example 1]
A fiber bundle of PAN-based carbon fibers having an average fiber diameter of 4 μm was cut to obtain short fibers having an average fiber length of 3 mm. These were defibrated in water using a slurry tank of a wet continuous paper making machine, and when sufficiently dispersed, short fibers of polyvinyl alcohol (PVA) as a binder were uniformly dispersed and fed out by a pressure device.

The dispersion is fed onto a mesh plate placed on the top of a perforated plate (stainless steel, 1 mm thick) having holes with a diameter of 6 mm and a pitch distance of 8 mm, and then dried with a dryer. Thus, a carbon fiber paper having a length of 200 m was obtained. In addition, the average mass per unit area of the obtained carbon fiber paper was 30 g / m ² .

  Next, this carbon fiber paper was impregnated with a thermosetting resin by a dip-nip method. That is, this carbon fiber paper was continuously fed into a tray containing a 20% by mass ethanol solution of phenol resin (Phenolite J-325 (trade name) manufactured by Dainippon Ink Chemical Co., Ltd.), and with a squeezing device. Excess phenol resin was squeezed and dried by blowing hot air continuously to obtain a resin-impregnated carbon fiber paper.

  Next, this resin-impregnated carbon fiber paper was continuously heated and pressed with a continuous belt device (manufactured by Mitsubishi Rayon Engineering Co., Ltd.) to obtain a resin-cured carbon fiber paper. At this time, the heat treatment temperature of the heating zone is 160 ° C., the heat treatment time is 5 minutes, the temperature of the curing zone is 250 ° C., the press pressure is 3 MPa, the press time is 2 seconds, and the belt speed is 0.00. It was 5 m / min.

  Subsequently, the resin-cured carbon fiber paper was carbonized by heating in a nitrogen gas atmosphere at 2000 ° C. for 10 minutes using a continuous firing furnace, to obtain a carbon electrode base material having a length of 190 m.

  The obtained carbon electrode substrate was measured for bending strength, deflection, gas permeability, and penetration resistance. The measurement results are shown in Table 1.

[Comparative Example 1]
A carbon electrode substrate was obtained in the same manner as in Example 1 except that the porous plate was not used. Carbon short fibers were uniformly distributed in the obtained carbon electrode base material. In addition, bending strength, deflection, gas permeability, and penetration resistance were measured for the obtained carbon electrode substrate. The measurement results are shown in Table 1.

Next, the carbon electrode base material obtained in Example 1 and Comparative Example 1 was cut into a 5 cm square, and water repellent treatment [commercially available PTFE aqueous solution (Mitsui / Dupont Fluoro Chemical Co., Ltd.) was used in water of 15 to 20 mass. So that the catalyst layer (mixed of carbon black and platinum catalyst) is 1.0 mg / cm ² on the substrate. An electrolyte membrane (manufactured by DuPont, trade name: Nafion 115) was sandwiched between the coated carbon electrode base materials to prepare a membrane electrode assembly. Next, the membrane electrode assembly was further sandwiched with a carbon separator and tightened with a tightening torque of 4 N · m to produce a single cell stack. Among the obtained single cell stacks, the one using the carbon electrode substrate produced by the method of Example 1 was designated as cell stack A, and the one using the carbon electrode substrate produced by the method of Example 2 was used as the cell stack. B.

  Fig. 1 shows the power generation characteristics of the above cell stack when power is generated at 80 ° C using hydrogen for the anode and oxygen for the cathode. Fig. 1 shows the power generation characteristics when power is generated at 80 ° C using hydrogen for the anode and air for the cathode. FIG. 2 shows the power generation characteristics of the cell stack. 1 and 2, the symbol (□) indicates the power generation characteristics of the cell stack A, and the symbol (Δ) indicates the power generation characteristics of the cell stack B. As apparent from FIGS. 1 and 2, it was found that the cell stack A can obtain a higher output voltage than the cell stack B, particularly in the high current density region.

  This is because, in the carbon electrode base material of Comparative Example 1, the diffusibility of the gas is hindered by the retention of water generated by the electrochemical reaction, and a rapid output decrease is observed in the high current density region. In the carbon electrode base material of Example 1 according to the present invention, the fuel gas is supplied from a portion having a relatively small structure of carbon short fibers, and the generated water is efficiently discharged from a relatively large portion of carbon short fibers. In particular, it is considered that good power generation characteristics were exhibited in a high current density region.

It is a figure which shows the electric power generation characteristic of a cell stack at the time of generating electric power at 80 degreeC using hydrogen for an anode and oxygen for a cathode. It is a figure which shows the electric power generation characteristic of a cell stack at the time of generating electric power at 80 degreeC using hydrogen for an anode and air for a cathode. It is the schematic of an example of the continuous belt apparatus which can be used by this invention. It is a figure which shows the arrangement | positioning condition of the net board and perforated board at the time of making a carbon short fiber, (a) is a bird's-eye view, (b) is a top view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Resin impregnated carbon fiber paper 2 ... Release agent coating base material 3 ... Belt 4 ... Heating zone 5 ... Curing zone

Claims (7)

(A) on the underside of the mesh plate used for papermaking, with a perforated plate in which holes are formed in a flat plate , making carbon short fibers to make carbon fiber paper;
(B) impregnating the carbon fiber paper with a thermosetting resin to obtain a resin-impregnated carbon fiber paper;
(C) heat-pressing the resin-impregnated carbon fiber paper to obtain a resin-cured carbon fiber paper;
(D) A method for producing a carbon electrode substrate, comprising: baking the resin-cured carbon fiber paper at a temperature of 1200 ° C. or higher in a nitrogen atmosphere to form a carbon electrode substrate. The method for producing a carbon electrode substrate according to claim 1, wherein the pore diameter of the porous plate is 4 to 10 mm, and the distance between pitches of the porous plate is 6 to 12 mm. The method for producing a carbon electrode substrate according to claim 1 or 2, wherein in the step (a), a binder of up to 5% by mass is used with respect to the short carbon fibers. The method for producing a carbon electrode substrate according to any one of claims 1 to 3, wherein each of the steps (b) to (d) is continuously performed. A continuous belt device comprising a heating zone capable of preheating the resin-impregnated carbon fiber paper and a curing zone capable of curing the thermosetting resin while pressing the resin-impregnated carbon fiber paper in the step (c). The method for producing a carbon electrode substrate according to claim 4, wherein: The temperature of the heating zone is 120 to 300 ° C., the passage time of the heating zone is 1 to 6 minutes, the temperature of the curing zone is 250 to 400 ° C. (but higher than the temperature of the heating zone), The method for producing a carbon electrode substrate according to claim 5, wherein the press pressure is 1 to 20 MPa. The method for producing a carbon electrode substrate according to claim 5 or 6, wherein a belt speed in the continuous belt device is 0.1 to 6.0 m / min.

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