WO2009110467A1 - Carbon fiber paper and manufacturing method for the same - Google Patents

Carbon fiber paper and manufacturing method for the same Download PDF

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Publication number
WO2009110467A1
WO2009110467A1 PCT/JP2009/053962 JP2009053962W WO2009110467A1 WO 2009110467 A1 WO2009110467 A1 WO 2009110467A1 JP 2009053962 W JP2009053962 W JP 2009053962W WO 2009110467 A1 WO2009110467 A1 WO 2009110467A1
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Prior art keywords
fiber paper
carbon fiber
holes
carbon
oxidized
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PCT/JP2009/053962
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French (fr)
Japanese (ja)
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浩之 龍田
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東邦テナックス株式会社
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Publication of WO2009110467A1 publication Critical patent/WO2009110467A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/023—Porous and characterised by the material
    • H01M8/0234—Carbonaceous material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M2008/1095—Fuel cells with polymeric electrolytes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a carbon fiber paper for a gas diffusion layer of a solid polymer electrolyte fuel cell and a method for producing the same.
  • the carbon fiber paper has a plurality of fine pores formed by gaps between fibers and a plurality of fine pores having a diameter larger than the pores and formed from one surface of the carbon fiber paper toward the other surface. With non-through holes
  • carbon fiber paper Compared with carbon fiber fabric, carbon fiber paper has a small thickness and a small number of fine pores formed by gaps between fibers. Carbon fiber paper has less unevenness in air permeability and thickness than carbon fiber non-woven fabric, and has excellent properties in mass transfer and heat transfer inside carbon fiber paper. Utilizing these properties, carbon fiber paper is used for gas diffusion layer electrode substrates for polymer electrolyte fuel cells, printed wiring board substrates, and the like.
  • a method in which a through-hole having a large diameter or a large groove width is formed in the gas diffusion layer compared to the diameter of a large number of fine pores formed in the gaps between fibers.
  • this gas diffusion layer has a low mechanical strength due to the presence of the through-holes or through-grooves, resulting in poor handling.
  • the presence of the through hole and the through groove reduces the contact area with the catalyst layer, and as a result, the contact resistance between them increases.
  • gas permeability is different between the portion where the through hole or the groove is present and the other portion, and there is a problem that the battery performance is deteriorated due to partial drying of the electrolyte membrane particularly in a low current density region.
  • the object of the present invention is to provide a carbon fiber paper and a method for producing the same that solve the above problems.
  • the object of the present invention is to prevent flooding and excessive drying of the electrolyte membrane in a wide range of battery reactions from high current density range and high humidification condition to low current density range and low humidification condition.
  • An object of the present invention is to provide a carbon fiber paper for a solid polymer electrolyte fuel cell gas diffusion layer, which is excellent in water management as a content, and as a result does not hinder battery reaction, and a method for producing the same.
  • Another object of the present invention is to provide a carbon fiber paper for a solid polymer electrolyte fuel cell gas diffusion layer having a uniform gas diffusibility and a low contact resistance with a catalyst layer, and a method for producing the same. .
  • the present inventor has intensively studied carbon fiber paper. As a result, non-through holes having a predetermined depth and larger diameter than the pores of the carbon fiber paper from one surface of the carbon fiber paper having small pores compared to the carbon fiber fabric to the other surface It has been found that carbon fiber paper having a plurality of carbon atoms is optimal as a solid polymer electrolyte type gas diffusion layer.
  • the present invention is as described below.
  • Carbon fiber paper having a depth of 20 to 80% of the thickness of the carbon fiber paper, and the number of non-through holes per unit area is 100 to 1000 / cm. 2.
  • Carbon fiber paper for solid polymer electrolyte fuel cell gas diffusion layer having a thickness of 50 to 400 ⁇ m.
  • Oxidized fiber paper obtained by forming a plurality of non-through holes from one surface of the oxidized fiber paper to the other surface by laser processing on the oxidized fiber paper, and then forming the non-through holes The paper is fired at a temperature of 1300 to 2500 ° C.
  • Carbon fiber paper having a plurality of non-through holes with an average hole diameter of 50 to 500 ⁇ m formed from one surface to the other surface, the depth of the non-through holes being 20 to 80% of the thickness of the carbon fiber paper A method for producing a carbon fiber paper for a solid polymer electrolyte fuel cell gas diffusion layer, wherein the number of non-through holes per unit area is 100 to 1000 holes / cm 2 and the thickness is 50 to 400 ⁇ m.
  • Oxidized fiber paper is subjected to laser processing to obtain an oxidized fiber paper having a plurality of through holes extending from one surface to the other surface, and then subjected to an opening treatment with the oxidized fiber paper having the through holes formed therein.
  • an adhesive type oxidized fiber paper having a plurality of non-through holes formed from one side of the attached oxidized fiber paper to the other side is obtained.
  • Non-through holes per unit area The number of 100 to 1000 / cm 2, a thickness of 50 to the solid polymer electrolyte fuel cell gas diffusion layer carbon fiber paper manufacturing method of a 400 [mu] m.
  • the carbon fiber paper of the present invention When the carbon fiber paper of the present invention is used as a gas diffusion layer of a solid polymer electrolyte fuel cell, the carbon fiber paper is disposed so that one surface of the carbon fiber paper on which the non-through holes are formed is located on the separator side.
  • the carbon fiber paper can be used under a wide range of battery reaction conditions from a high current density region and a high humidification condition to a low current density region and a low humidification condition. Exhibits excellent water management capabilities as a gas diffusion layer.
  • the generated water is quickly discharged through the non-through hole formed in the gas diffusion layer, and the battery reaction is reduced by flooding. To prevent.
  • the holes formed from one side of the carbon fiber paper to the other side are non-through holes.
  • FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a solid polymer electrolyte fuel cell incorporating the carbon fiber paper of the present invention.
  • FIG. 2 is a graph showing the relationship between the current density and the voltage under high humidification conditions of the solid polymer electrolyte fuel cells incorporating the carbon fiber papers of Examples 1 to 3 and Comparative Examples 1 to 4.
  • FIG. 3 is a graph showing the relationship between the current density and voltage under low humidification conditions of the solid polymer electrolyte fuel cells incorporating the carbon fiber papers of Examples 1 to 3 and Comparative Examples 1 to 4.
  • FIG. 1 is a conceptual diagram showing an example of a solid polymer electrolyte fuel cell incorporating the carbon fiber paper of the present invention, and is a cross-sectional view along a plane orthogonal to the surface of the carbon fiber paper.
  • a solid polymer electrolyte fuel cell 2 includes an electrolyte membrane 4, catalyst layers 6 and 8 that function as a pair of electrodes, a pair of gas diffusion layers 10 and 12 made of carbon fiber paper, A pair of separators 14 and 16 are the main constituent members. One cell is formed by these main components.
  • the soot electrolyte membrane 4 is made of a solid polymer having proton conductivity such as a cation exchange resin membrane.
  • catalyst layers 6 and 8 containing a noble metal catalyst are arranged on both outer sides of the electrolyte membrane 4.
  • the catalyst layers 6 and 8 function as a pair of electrodes.
  • One catalyst layer 6 is an anode
  • the other catalyst layer 8 is a cathode.
  • a pair of gas diffusion layers 10 and 12 made of carbon fiber paper are disposed outside the electrodes made of the catalyst layers 6 and 8.
  • the soot gas diffusion layer 10 permeates and diffuses hydrogen gas, methanol or the like of fuel supplied to the fuel cell from the outside of the fuel cell, and supplies it to the catalyst layer 6.
  • the gas diffusion layer 12 supplies oxygen gas supplied from the outside of the fuel cell to the fuel cell and an oxidizing agent such as air to the catalyst layer 8 through the gas diffusion layer 12.
  • an oxidizing agent such as air
  • protons, oxidant, and electrons react to generate water.
  • the gas diffusion layer 12 has a role of discharging generated water through the gas diffusion layer 12 to the outside.
  • Separators 14 and 16 are disposed outside the gas diffusion layers 10 and 12, respectively. On the surface of the separator 14 where the separator 14 and the gas diffusion layer 10 are in contact, a flow path (not shown) for supplying fuel is provided. On the surface of the separator 16 where the separator 16 and the gas diffusion layer 12 are in contact with each other, a flow path (not shown) for supplying an oxidant and discharging water is provided.
  • the fuel (for example, hydrogen) supplied from the outside to the solid polymer electrolyte fuel cell 2 is sent to the catalyst layer 6, and protons and electrons are generated by the action of the catalyst of the catalyst layer 6.
  • This proton passes through the electrolyte membrane 4 and reaches the catalyst layer 8.
  • the electrons are sent to the catalyst layer 8 through an external load circuit (not shown). In the catalyst layer 8, the electrons, the protons, and the oxidizing agent are combined to generate water.
  • the proton conductivity of the electrolyte membrane 4 varies depending on the water content in the electrolyte membrane 4. When the water content is high, the proton conductivity increases, and when the water content is low, the proton conductivity decreases.
  • Water management includes drainage management of water generated at the cathode formed of the catalyst layer 8 and water retention management of the electrolyte membrane 4. It is necessary to carry out water management at the same time.
  • the carbon fiber paper of the present invention is a carbon having pores formed by gaps between carbon fibers constituting the carbon fiber paper and a plurality of non-through holes 18 formed from one surface toward the other surface. Fiber paper.
  • the average pore diameter of the pores formed by the gaps between the carbon fibers is 10 to 20 ⁇ m, preferably 12 to 18 ⁇ m, more preferably 13 to 17 ⁇ m.
  • the average pore diameter of the pores can be controlled by adjusting the fiber diameter of the carbon fiber, the amount of the organic polymer described later, the pressure of the thermal compression treatment described later, and the like.
  • the average hole diameter of the plurality of non-through holes 18 formed from one surface to the other surface is 50 to 500 ⁇ m, preferably 90 to 250 ⁇ m, and more preferably 110 to 200 ⁇ m.
  • the depth of the non-through hole 18 is 20 to 80%, preferably 30 to 70%, more preferably 40 to 60% of the thickness of the carbon fiber paper.
  • the mass transferability between the portion of the carbon fiber paper where the non-through hole exists and the portion where the non-through hole does not exist is increased. Spots appear.
  • carbon fiber paper is used for the gas diffusion layer, it is difficult to supply gas uniformly to the catalyst layer 8. As a result, local drying of the electrolyte membrane occurs, and eventually the power generation performance of the fuel cell is likely to deteriorate. Furthermore, the strength of the carbon fiber paper is reduced.
  • Non number of the through holes is preferably 100 to 1,000 / cm 2 per unit area, more preferably 300-500 amino / cm 2.
  • the carbon fiber paper of the present invention contains fibrous carbon and non-fibrous carbon.
  • the ratio of fibrous carbon in the carbon fiber paper is 20% by mass or more, preferably 40% by mass or more in order to increase strength and conductivity. 60 to 90% by mass is more preferable.
  • the thickness of the carbon fiber paper is preferably 50 to 400 ⁇ m, more preferably 80 to 300 ⁇ m, and particularly preferably 100 to 250 ⁇ m.
  • Fibrous carbon is derived from oxidized fibers in the raw oxidized fiber paper.
  • Non-fibrous carbon is derived from an organic polymer that is mixed with the oxidized fiber as a binder when the raw oxidized fiber paper is produced by wet papermaking.
  • the oxidized fiber becomes fibrous carbon, and the organic polymer becomes non-fibrous carbon.
  • a plurality of non-through holes are formed from one side of the raw oxidized fiber paper to the other side by subjecting the raw oxidized fiber paper to a hole processing by laser processing.
  • An example is a method in which the oxidized fiber paper is obtained and then the oxidized fiber paper in which the non-through holes are formed is baked and carbonized at 1300 to 2500 ° C. in an inert atmosphere.
  • the oxidized fiber paper is subjected to an opening treatment by laser processing to obtain an oxidized fiber paper having a plurality of through holes extending from one surface to the other surface, and then the oxidized fiber paper having the through holes formed therein.
  • an opening treatment by laser processing to obtain an oxidized fiber paper having a plurality of through holes extending from one surface to the other surface, and then the oxidized fiber paper having the through holes formed therein.
  • Oxidized fiber paper as a raw material for producing the present carbon fiber paper can be produced by mixing oxidized fiber having a predetermined fiber length and an organic polymer, and making paper by an existing wet papermaking method.
  • Oxidized fibers such as polyacrylonitrile (PAN), pitch-based, phenolic, and rayon-based oxidized fibers can be used as the oxidized fibers.
  • PAN polyacrylonitrile
  • the average fiber thickness of the oxidized fiber is preferably 0.5 to 5.0 dtex.
  • the average fiber length of the oxidized fiber is preferably 3 to 52 mm, more preferably 3 to 10 mm.
  • organic polymer aromatic polyamide (aramid), phenol resin, polyimide, PAN, and the like are preferable because of the high residual carbon ratio after carbonization.
  • the organic polymer can be used in any form such as liquid, powder, pellet, short fiber, and pulp.
  • the raw oxidized fiber paper is preferably oxidized fiber paper that has been subjected to heat compression treatment for the purpose of homogenization and high bulk density.
  • the heat compression treatment is preferably carried out at a temperature of 100 to 350 ° C. under a pressure of 0.30 to 20 MPa. By this treatment, the bulk density of the raw oxidized fiber paper is controlled to 1.0 to 0.2 g / cm 3 .
  • the hot compression process can be performed by, for example, calendaring or pressing.
  • the raw oxidized fiber paper whose pore diameter is controlled in this way is subjected to a hole opening process by laser processing described later.
  • the raw oxidized fiber paper is subjected to an opening process using a laser processing apparatus to form non-through holes.
  • the diameter of the non-through hole is preferably 54 to 540 ⁇ m.
  • the number of apertures is preferably 100 to 10,000 / cm 2 .
  • the depth of the non-through hole is preferably 20 to 80% of the thickness of the oxidized fiber paper.
  • the laser processing apparatus YAG, CO2, a semiconductor laser, or the like can be used.
  • laser processing conditions laser irradiation conditions in a conventionally known carbon dioxide gas laser or the like can be appropriately employed.
  • a wavelength of 9.3 to 10.6 ⁇ m in the infrared wavelength range is generally used, and the energy is preferably 4 to 60 mJ.
  • through-holes may be formed in the oxidized fiber paper to obtain a porous oxidized fiber paper, and non-porous oxidized fiber paper that has not been subjected to opening treatment may be bonded to the porous fiber fiber paper.
  • the opening conditions of the porous oxidized fiber conform to the opening conditions of the non-through holes.
  • thermocompression bonding there is a method of thermocompression bonding the two using the organic compound. Moreover, you may bond both together with the adhesive agent which melt
  • the oxidized fiber paper is preferably pre-fired at about 500 ° C. in an inert gas atmosphere such as nitrogen. Thereafter, it is carbonized by firing at 1300 to 2500 ° C. in an inert gas atmosphere such as nitrogen to obtain a carbon fiber paper.
  • the rate of temperature increase is preferably 200 ° C./min or less.
  • the carbon fiber paper obtained by the above manufacturing method has a plurality of non-through holes with an average pore diameter of 50 to 500 ⁇ m formed from one side to the other side.
  • the depth of the non-through hole is 20 to 80% of the thickness of the carbon fiber paper.
  • This carbon fiber paper has pores with an average pore diameter of 10 to 20 ⁇ m formed by the gaps between the carbon fibers constituting the carbon fiber paper.
  • This carbon fiber paper has an air permeability defined by JIS L 1096 of 10,000 ml / min or more, no film-like carbide is formed on the surface, and a bending strength of 10 MPa or more.
  • the carbon fiber paper has a thickness of 50 to 400 ⁇ m, a basis weight of 20 to 180 g / m 2 , and a bulk density of 0.2 to 0.6 g / cm 3 .
  • Non-through holes in oxidized fiber paper and carbon fiber paper Using a digital microscope (manufactured by KEYENCE, trade name: VH-8000C), various dimensions of non-through holes of oxidized fiber paper and carbon fiber paper were measured. From these measured values, the average non-through hole diameter and non-through hole density were determined by the above-described calculation method.
  • Example 1 Polyacrylonitrile (PAN) oxidized fiber (average fiber thickness 2.2 dtex, average fiber length 5 mm, specific gravity 1.42) as oxidized fiber, and aramid fibrid (average fiber length 1.2 mm, manufactured by DuPont) as organic polymer ) And polyethylene terephthalate (PET) fibers (average fiber thickness 2.5 dtex, average fiber length 5 mm) were mixed so that the blending ratio was 65/15/20 mass%. This mixture was subjected to wet paper making to obtain a raw oxidized fiber paper.
  • PAN Polyacrylonitrile
  • PET polyethylene terephthalate
  • the basis weight is 147 g / m 2
  • the thickness is 320 ⁇ m
  • the bulk density is 0.46 g / cm 3
  • the gap between the oxidized fibers Oxidized fiber paper having an average pore diameter of 17 ⁇ m was obtained.
  • the oxidized fiber paper is subjected to a hole opening process by a laser processing apparatus, and the oxidized fiber has non-through holes having a diameter of 220 ⁇ m, a depth of 240 ⁇ m (75% of the thickness of the oxidized fiber paper), and a non-through hole density of 320 / cm 2. I got paper.
  • the oxidized fiber paper was fired at 500 ° C. for 10 minutes in a nitrogen gas atmosphere, and then at 2000 ° C. for 10 minutes.
  • a carbon fiber paper having a basis weight of 75 g / m 2 , a thickness of 200 ⁇ m, and a bulk density of 0.375 g / cm 3 was obtained.
  • Example 2 Carbon fiber paper was obtained in the same manner as in Example 1 except that the depth of the non-through hole of the oxidized fiber paper was 80 ⁇ m (25% of the thickness of the oxidized fiber paper). As shown in Table 1, this carbon fiber paper has a non-through hole diameter of 202 ⁇ m, a non-through hole depth of 50 ⁇ m (25% of the thickness of the carbon fiber paper), and a non-through hole density of 400 holes / cm 2. The average pore diameter of the pores formed by the gaps between the fibers was 15 ⁇ m.
  • Example 3 An oxidized fiber paper having a basis weight of 72 g / m 2 , a thickness of 160 ⁇ m, a bulk density of 0.45 g / cm 3 , and an average pore diameter of 17 ⁇ m formed by gaps between fibers is subjected to a hole opening treatment with a laser processing apparatus, and the diameter A porous oxidized fiber paper having through holes of 220 ⁇ m and 320 pieces / cm 2 was obtained.
  • non-porous oxidized fiber paper having a basis weight of 72 g / m 2 , a thickness of 160 ⁇ m, a bulk density of 0.45 g / cm 3 , and an average pore diameter of 17 ⁇ m of pores formed by the gaps between fibers was laminated, A patch-type oxidized fiber paper was obtained.
  • This sticky oxidized fiber paper was baked and carbonized under the same conditions as in Example 1 to obtain a carbon fiber paper having a basis weight of 75 g / m 2 , a thickness of 200 ⁇ m, and a bulk density of 0.375 g / cm 3 .
  • this carbon fiber paper has a non-through hole diameter of 202 ⁇ m, a non-through hole depth of 100 ⁇ m (50% of the thickness of the carbon fiber paper), and a non-through hole density of 400 holes / cm 2.
  • the average pore diameter of the pores formed by the gaps between the fibers was 15 ⁇ m.
  • Examples 4 to 9 The carbon fiber paper shown in Table 1 was obtained by operating in the same manner as in Example 1.
  • Example 1 A carbon fiber paper was obtained in the same manner as in Example 1 except that the oxidized fiber paper was not subjected to the hole opening treatment. This carbon fiber paper was confirmed to have no through holes and non-through holes with a diameter of 50 ⁇ m or more. The average pore diameter of the pores formed by the gaps between the fibers was 15 ⁇ m.
  • Carbon fiber paper was obtained in the same manner as in Example 1 except that the depth of the non-through hole of the oxidized fiber paper was 40 ⁇ m (12.5% of the thickness of the oxidized fiber paper).
  • this carbon fiber paper has a non-through hole diameter of 202 ⁇ m, a non-through hole depth of 25 ⁇ m (12.5% of the thickness of the carbon fiber paper), and a non-through hole density of 400 /
  • the average pore diameter of the pores formed by cm 2 and the gap between the fibers was 15 ⁇ m.
  • Example 3 A carbon fiber paper was obtained in the same manner as in Example 1 except that the depth of the non-through hole of the oxidized fiber paper was 280 ⁇ m (87.5% of the thickness of the oxidized fiber paper).
  • this carbon fiber paper has a non-through hole diameter of 202 ⁇ m, a non-through hole depth of 175 ⁇ m (87.5% of the thickness of the carbon fiber paper), and a non-through hole density of 400 /
  • the average pore diameter of the pores formed by cm 2 and the gap between the fibers was 15 ⁇ m.
  • Carbon fiber paper was obtained in the same manner as in Example 1 except that the hole was penetrated in the opening process of the oxidized fiber paper. As shown in Table 2, the carbon fiber paper has a through hole diameter of 202 ⁇ m, a through hole depth of 202 ⁇ m (100% of the thickness of the carbon fiber paper), and a surface density of the through holes of 400 pieces / cm 2 . The average pore diameter of the pores formed by the gaps between the fibers was 15 ⁇ m.
  • the carbon fiber paper obtained in Examples 4 to 9 was evaluated in the same manner. Tables 1 and 2 list the maximum reached current density.
  • the carbon fiber papers obtained in Examples 4 to 9 had a high current density of 0.7 A / cm 2 under both high and low humidification conditions.

Abstract

Disclosed is a carbon fiber paper for diffusing solid polyelectrolyte fuel cell gas, having fine pores with an average diameter of 10−20μm formed in the gaps of carbon fibers that constitute the carbon fiber paper, and a plurality of non-penetrating pores with an average diameter of 50−500μm formed in the direction from one surface toward the other. The carbon fiber paper has a thickness of 50−400μm, and the non-penetrating pores of the carbon fiber paper have depths of 20−80% of the carbon fiber paper thickness, and a unit area count of 100−1000 pores/cm2.

Description

炭素繊維紙及びその製造方法Carbon fiber paper and manufacturing method thereof
  本発明は、固体高分子電解質型燃料電池のガス拡散層用炭素繊維紙、及びその製造方法に関する。この炭素繊維紙は、繊維同士の間隙で形成される多数の微細な細孔と、前記細孔よりも大径で、炭素繊維紙の一方の面から他方の面に向かって形成された複数の非貫通孔とを有する The present invention relates to a carbon fiber paper for a gas diffusion layer of a solid polymer electrolyte fuel cell and a method for producing the same. The carbon fiber paper has a plurality of fine pores formed by gaps between fibers and a plurality of fine pores having a diameter larger than the pores and formed from one surface of the carbon fiber paper toward the other surface. With non-through holes
  炭素繊維紙は、炭素繊維織物と比較すると、厚みや、繊維同士の間隙で形成される多数の微細な細孔の孔径が小さい。炭素繊維紙は、炭素繊維不織布と比較すると、通気性や厚みに斑が少なく、炭素繊維紙内部における物質移動、伝熱に優れた性質を有する。これらの性質を利用し、炭素繊維紙は、高分子電解質型燃料電池用のガス拡散層電極基材や、プリント配線板用基材などに用いられている。 Compared with carbon fiber fabric, carbon fiber paper has a small thickness and a small number of fine pores formed by gaps between fibers. Carbon fiber paper has less unevenness in air permeability and thickness than carbon fiber non-woven fabric, and has excellent properties in mass transfer and heat transfer inside carbon fiber paper. Utilizing these properties, carbon fiber paper is used for gas diffusion layer electrode substrates for polymer electrolyte fuel cells, printed wiring board substrates, and the like.
  前記ガス拡散層に炭素繊維紙の様な多孔質体を用いる燃料電池は、高電流密度域及び高加湿条件下で発電をする場合、発電時に生成される水がガス拡散層に滞留することがある。この場合には、拡散層を通して触媒層に供給される酸化剤ガスが前記水により遮断され、発電が停止することが起る(フラッディング現象)。他方、低電流密度域及び低加湿条件下で発電をする場合は、発電時に生成される水が減少し、その結果電解質膜が乾燥し、電池性能が低下することが起きる。 In a fuel cell using a porous material such as carbon fiber paper for the gas diffusion layer, when power is generated under a high current density region and a high humidification condition, water generated during power generation may stay in the gas diffusion layer. is there. In this case, the oxidant gas supplied to the catalyst layer through the diffusion layer is blocked by the water, and power generation stops (flooding phenomenon). On the other hand, when power generation is performed under a low current density region and a low humidification condition, water generated during power generation is reduced, and as a result, the electrolyte membrane is dried and battery performance is degraded.
  上記問題を解決するため、繊維同士の間隙で形成される多数の微細な細孔の孔径と比較して大径の貫通孔又は溝幅の大きな貫通溝を、ガス拡散層に形成する方法が提案されている(例えば、特許文献１～４参照)。しかし、このガス拡散層は、貫通孔又は貫通溝の存在により、機械的強度が低くなり、取扱性が悪くなる。更に、貫通孔や貫通溝が存在することにより、触媒層との接触面積が減少し、その結果両者間の接触抵抗が増大する。更には、貫通孔又は貫通溝の存在する部分と、それ以外の部分とでガス透過性が異なり、特に低電流密度域では電解質膜の部分的な乾燥により電池性能が低下する問題がある。 In order to solve the above problem, a method is proposed in which a through-hole having a large diameter or a large groove width is formed in the gas diffusion layer compared to the diameter of a large number of fine pores formed in the gaps between fibers. (For example, see Patent Documents 1 to 4). However, this gas diffusion layer has a low mechanical strength due to the presence of the through-holes or through-grooves, resulting in poor handling. Furthermore, the presence of the through hole and the through groove reduces the contact area with the catalyst layer, and as a result, the contact resistance between them increases. Furthermore, gas permeability is different between the portion where the through hole or the groove is present and the other portion, and there is a problem that the battery performance is deteriorated due to partial drying of the electrolyte membrane particularly in a low current density region.
  上記問題を解決するために、カーボンペーパー等の基材上に黒鉛粒子を用いてガス拡散膜を形成し、そのガス拡散膜の表面から裏面に向けて凹部を形成する方法が提案されている(例えば、特許文献５参照)。しかし、この黒鉛粒子のガス拡散膜は通気性が悪く、特に高電流密度域において、フラッディング現象を充分に防止できていない。
特開２００７－１０３２４１号公報  (特許請求の範囲) 特開２００６－３３１７８６号公報  (特許請求の範囲) 特開２００５－１０８８２０号公報  (特許請求の範囲) 特開２００４－１５２５８４号公報  (特許請求の範囲) 特開２００６－４７８７号公報  (特許請求の範囲) In order to solve the above problem, a method of forming a gas diffusion film using graphite particles on a substrate such as carbon paper and forming a recess from the front surface to the back surface of the gas diffusion film has been proposed ( For example, see Patent Document 5). However, the gas diffusion film of graphite particles has poor air permeability and cannot sufficiently prevent the flooding phenomenon particularly in a high current density region.
JP 2007-103241 A (Claims) JP 2006-331786 A (Claims) Japanese Patent Laying-Open No. 2005-108820 (Claims) JP 2004-152584 A (Claims) JP 2006-4787 A (Claims)
  本発明の目的とするところは、上記問題を解決した炭素繊維紙及びその製造方法を提供することにある。 The object of the present invention is to provide a carbon fiber paper and a method for producing the same that solve the above problems.
  具体的には、本発明の目的は、高電流密度域及び高加湿条件から、低電流密度域及び低加湿条件までの広範囲な電池反応において、フラッディングや電解質膜の過度の乾燥を防止することを内容とする水管理性に優れ、その結果電池反応を阻害することが無い固体高分子電解質型燃料電池ガス拡散層用炭素繊維紙及びその製造方法を提供することにある。 Specifically, the object of the present invention is to prevent flooding and excessive drying of the electrolyte membrane in a wide range of battery reactions from high current density range and high humidification condition to low current density range and low humidification condition. An object of the present invention is to provide a carbon fiber paper for a solid polymer electrolyte fuel cell gas diffusion layer, which is excellent in water management as a content, and as a result does not hinder battery reaction, and a method for producing the same.
　本発明の他の目的は、ガス拡散性が均一であり、また更に触媒層との接触抵抗の低い固体高分子電解質型燃料電池ガス拡散層用炭素繊維紙及びその製造方法を提供することにある。 Another object of the present invention is to provide a carbon fiber paper for a solid polymer electrolyte fuel cell gas diffusion layer having a uniform gas diffusibility and a low contact resistance with a catalyst layer, and a method for producing the same. .
  上記目的を達成するために、本発明者は炭素繊維紙について鋭意検討した。その結果、炭素繊維織物と比較して小さな細孔を有する炭素繊維紙の一方の面から他方の面に向かって、所定の深さで炭素繊維紙の前記細孔よりも大径の非貫通孔を複数有する炭素繊維紙が固体高分子電解質型ガス拡散層として最適であることを見出した。 達成 In order to achieve the above object, the present inventor has intensively studied carbon fiber paper. As a result, non-through holes having a predetermined depth and larger diameter than the pores of the carbon fiber paper from one surface of the carbon fiber paper having small pores compared to the carbon fiber fabric to the other surface It has been found that carbon fiber paper having a plurality of carbon atoms is optimal as a solid polymer electrolyte type gas diffusion layer.
  本発明は、以下に記載のものである。 The present invention is as described below.
  ［１］  炭素繊維紙を構成する炭素繊維同士の間隙で形成される平均孔径が１０～２０μｍの細孔と、一方の面から他方の面に向かって形成される平均孔径が５０～５００μｍの複数の非貫通孔とを有する炭素繊維紙であって、非貫通孔の深さが炭素繊維紙の厚みの２０～８０％であり、単位面積当りの非貫通孔の数が１００～１０００個／ｃｍ２であり、厚みが５０～４００μｍである固体高分子電解質型燃料電池ガス拡散層用炭素繊維紙。 [1] A pore having an average pore diameter of 10 to 20 μm formed by a gap between carbon fibers constituting carbon fiber paper and a plurality of pores having an average pore diameter of 50 to 500 μm formed from one surface to the other surface. Carbon fiber paper having a depth of 20 to 80% of the thickness of the carbon fiber paper, and the number of non-through holes per unit area is 100 to 1000 / cm. 2. Carbon fiber paper for solid polymer electrolyte fuel cell gas diffusion layer having a thickness of 50 to 400 μm.
  ［２］  炭素繊維紙が、繊維状炭素と非繊維状炭素とを含み、炭素繊維紙中の繊維状炭素の割合が２０質量％以上である[１]に記載の炭素繊維紙。 [2] The carbon fiber paper according to [1], wherein the carbon fiber paper contains fibrous carbon and non-fibrous carbon, and the proportion of the fibrous carbon in the carbon fiber paper is 20% by mass or more.
　[３]　カソード側のガス拡散層に用いる[１]に記載の炭素繊維紙。 [3] The carbon fiber paper according to [1] used for the gas diffusion layer on the cathode side.
  [４]  酸化繊維紙にレーザー加工をすることにより、酸化繊維紙の一方の面から他方の面に向かう非貫通孔を複数形成した酸化繊維紙を得、次いで前記非貫通孔を形成した酸化繊維紙を不活性雰囲気下、１３００～２５００℃の温度で焼成することを特徴とする、炭素繊維紙を構成する炭素繊維同士の間隙で形成される平均孔径が１０～２０μｍの細孔と、一方の面から他方の面に向かって形成される平均孔径が５０～５００μｍの複数の非貫通孔とを有する炭素繊維紙であって、非貫通孔の深さが炭素繊維紙の厚みの２０～８０％であり、単位面積当りの非貫通孔の数が１００～１０００個／ｃｍ２であり、厚みが５０～４００μｍである固体高分子電解質型燃料電池ガス拡散層用炭素繊維紙の製造方法。 [4] Oxidized fiber paper obtained by forming a plurality of non-through holes from one surface of the oxidized fiber paper to the other surface by laser processing on the oxidized fiber paper, and then forming the non-through holes The paper is fired at a temperature of 1300 to 2500 ° C. in an inert atmosphere, and pores having an average pore diameter of 10 to 20 μm formed by gaps between carbon fibers constituting the carbon fiber paper, Carbon fiber paper having a plurality of non-through holes with an average hole diameter of 50 to 500 μm formed from one surface to the other surface, the depth of the non-through holes being 20 to 80% of the thickness of the carbon fiber paper A method for producing a carbon fiber paper for a solid polymer electrolyte fuel cell gas diffusion layer, wherein the number of non-through holes per unit area is 100 to 1000 holes / cm 2 and the thickness is 50 to 400 μm.
  [５]  酸化繊維紙にレーザー加工することにより、一方の面から他方の面にわたる貫通孔を複数形成した酸化繊維紙を得、次いで前記貫通孔を形成した酸化繊維紙と、開孔処理を施していない酸化繊維紙とを貼付けることにより、貼付けた酸化繊維紙の一方の面から他方の面に向かう非貫通孔を複数形成した貼付型酸化繊維紙を得、次いで前記貼付型酸化繊維紙を不活性雰囲気下、１３００～２５００℃の温度で焼成することを特徴とする、炭素繊維紙を構成する炭素繊維同士の間隙で形成される平均孔径が１０～２０μｍの細孔と、一方の面から他方の面に向かって形成される平均孔径が５０～５００μｍの複数の非貫通孔とを有する炭素繊維紙であって、非貫通孔の深さが炭素繊維紙の厚みの２０～８０％であり、単位面積当りの非貫通孔の数が１００～１０００個／ｃｍ２であり、厚みが５０～４００μｍである固体高分子電解質型燃料電池ガス拡散層用炭素繊維紙の製造方法。 [5] Oxidized fiber paper is subjected to laser processing to obtain an oxidized fiber paper having a plurality of through holes extending from one surface to the other surface, and then subjected to an opening treatment with the oxidized fiber paper having the through holes formed therein. By sticking the non-oxidized fiber paper, an adhesive type oxidized fiber paper having a plurality of non-through holes formed from one side of the attached oxidized fiber paper to the other side is obtained. Fine pores having an average pore diameter of 10 to 20 μm formed by gaps between carbon fibers constituting carbon fiber paper, characterized by firing at a temperature of 1300 to 2500 ° C. in an inert atmosphere, from one side Carbon fiber paper having a plurality of non-through holes with an average hole diameter of 50 to 500 μm formed toward the other surface, and the depth of the non-through holes is 20 to 80% of the thickness of the carbon fiber paper , Non-through holes per unit area The number of 100 to 1000 / cm 2, a thickness of 50 to the solid polymer electrolyte fuel cell gas diffusion layer carbon fiber paper manufacturing method of a 400 [mu] m.
  本発明の炭素繊維紙を、固体高分子電解質型燃料電池のガス拡散層として用いる場合、本炭素繊維紙の、非貫通孔が形成されている一方の面を、セパレータ側に位置するように配置し、他方の面を触媒層側に位置するように配置することにより、高電流密度域及び高加湿条件から低電流密度域及び低加湿条件までの広範囲な電池反応条件下において、本炭素繊維紙は、ガス拡散層として優れた水管理能力を発揮する。 When the carbon fiber paper of the present invention is used as a gas diffusion layer of a solid polymer electrolyte fuel cell, the carbon fiber paper is disposed so that one surface of the carbon fiber paper on which the non-through holes are formed is located on the separator side. However, by arranging the other side to be located on the catalyst layer side, the carbon fiber paper can be used under a wide range of battery reaction conditions from a high current density region and a high humidification condition to a low current density region and a low humidification condition. Exhibits excellent water management capabilities as a gas diffusion layer.
  すなわち、一方の電池反応条件の高電流密度域及び高加湿条件下では、発生した水は、ガス拡散層内に形成される非貫通孔を通って速やかに排出され、フラッディングによる電池反応の低下を防止する。 That is, under the high current density region and high humidification condition of one battery reaction condition, the generated water is quickly discharged through the non-through hole formed in the gas diffusion layer, and the battery reaction is reduced by flooding. To prevent.
　本発明の炭素繊維紙をガス拡散層として用いる場合、炭素繊維紙の一面から他面方向に形成された孔は非貫通孔である。その結果、低電流密度域及び低加湿条件の電池反応条件下であっても、電解質膜の部分的な乾燥による電池性能の低下抑制することが出来るとともに、触媒層との接触抵抗の増大も抑制することができる。 When the carbon fiber paper of the present invention is used as a gas diffusion layer, the holes formed from one side of the carbon fiber paper to the other side are non-through holes. As a result, it is possible to suppress a decrease in battery performance due to partial drying of the electrolyte membrane, and an increase in contact resistance with the catalyst layer, even under battery reaction conditions in a low current density region and a low humidification condition. can do.
　これに対し、貫通孔を有する従来の炭素繊維紙をガス拡散層として用いる場合、低電流密度域及び低加湿条件の電池反応条件下では、貫通孔による供給ガスの局部的な集中による電解質膜の部分的な乾燥による電池性能の低下が起こるとともに、触媒層との接触抵抗も増大する。 In contrast, when a conventional carbon fiber paper having a through hole is used as a gas diffusion layer, the electrolyte membrane due to the local concentration of the supply gas through the through hole under the battery reaction conditions in a low current density region and a low humidification condition. Battery performance decreases due to partial drying, and contact resistance with the catalyst layer also increases.
図１は、本発明の炭素繊維紙を組込んだ固体高分子電解質型燃料電池の一構成例を示す概略断面図である。FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a solid polymer electrolyte fuel cell incorporating the carbon fiber paper of the present invention. 図２は、実施例１～３、比較例１～４の炭素繊維紙を組込んだ固体高分子電解質型燃料電池の、高加湿条件下における電流密度と電圧との関係を示すグラフである。FIG. 2 is a graph showing the relationship between the current density and the voltage under high humidification conditions of the solid polymer electrolyte fuel cells incorporating the carbon fiber papers of Examples 1 to 3 and Comparative Examples 1 to 4. 図３は、実施例１～３、比較例１～４の炭素繊維紙を組込んだ固体高分子電解質型燃料電池の、低加湿条件下における電流密度と電圧との関係を示すグラフである。FIG. 3 is a graph showing the relationship between the current density and voltage under low humidification conditions of the solid polymer electrolyte fuel cells incorporating the carbon fiber papers of Examples 1 to 3 and Comparative Examples 1 to 4.
符号の説明Explanation of symbols
  ２    固体高分子電解質型燃料電池
  ４    電解質膜
  ６、８    触媒層
  １０、１２    炭素繊維紙
  １４、１６    セパレータ
  １８    非貫通孔 2 Solid Polymer Electrolyte Fuel Cell 4 Electrolyte Membrane 6, 8 Catalyst Layer 10, 12 Carbon Fiber Paper 14, 16 Separator 18 Non-Through Hole
  以下、本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail.
  図１は、本発明の炭素繊維紙を組込んだ固体高分子電解質型燃料電池の一例を示す概念図であって、炭素繊維紙の表面に直交する面に沿った断面図である。 FIG. 1 is a conceptual diagram showing an example of a solid polymer electrolyte fuel cell incorporating the carbon fiber paper of the present invention, and is a cross-sectional view along a plane orthogonal to the surface of the carbon fiber paper.
  図１に示すように、固体高分子電解質型燃料電池２は、電解質膜４と、一対の電極として作用する触媒層６、８と、炭素繊維紙からなる一対のガス拡散層１０、１２と、一対のセパレータ１４、１６を主要構成部材としている。これらの主要構成部材で一つのセルが形成されている。 As shown in FIG. 1, a solid polymer electrolyte fuel cell 2 includes an electrolyte membrane 4, catalyst layers 6 and 8 that function as a pair of electrodes, a pair of gas diffusion layers 10 and 12 made of carbon fiber paper, A pair of separators 14 and 16 are the main constituent members. One cell is formed by these main components.
  電解質膜４は、陽イオン交換樹脂膜等のプロトン伝導性を持つ固体高分子からなる。電解質膜４の両外側には、貴金属触媒を含む触媒層６、８が配置されている。この触媒層６、８は、一対の電極として作用する。一方の触媒層６はアノードで、他方の触媒層８はカソードである。触媒層６、８からなる電極のそれぞれの外側には、炭素繊維紙からなる一対のガス拡散層１０、１２が配置される。 The soot electrolyte membrane 4 is made of a solid polymer having proton conductivity such as a cation exchange resin membrane. On both outer sides of the electrolyte membrane 4, catalyst layers 6 and 8 containing a noble metal catalyst are arranged. The catalyst layers 6 and 8 function as a pair of electrodes. One catalyst layer 6 is an anode, and the other catalyst layer 8 is a cathode. A pair of gas diffusion layers 10 and 12 made of carbon fiber paper are disposed outside the electrodes made of the catalyst layers 6 and 8.
  ガス拡散層１０は、燃料電池の外部から燃料電池に供給される燃料の水素ガスやメタノール等を透過、拡散させて、触媒層６に供給する。 The soot gas diffusion layer 10 permeates and diffuses hydrogen gas, methanol or the like of fuel supplied to the fuel cell from the outside of the fuel cell, and supplies it to the catalyst layer 6.
　ガス拡散層１２は、燃料電池の外部から燃料電池に供給される酸素ガスや、空気等の酸化剤を、ガス拡散層１２を通して触媒層８に供給する。触媒層８においては、プロトンと酸化剤と、電子とが反応して水を生成する。ガス拡散層１２は、生成する水をガス拡散層１２を通して外部に排出させる役割を持つ。 The gas diffusion layer 12 supplies oxygen gas supplied from the outside of the fuel cell to the fuel cell and an oxidizing agent such as air to the catalyst layer 8 through the gas diffusion layer 12. In the catalyst layer 8, protons, oxidant, and electrons react to generate water. The gas diffusion layer 12 has a role of discharging generated water through the gas diffusion layer 12 to the outside.
　ガス拡散層１０、１２のそれぞれの外側には、セパレータ１４、１６が配置される。セパレータ１４とガス拡散層１０とが接するセパレータ１４の表面には、燃料を供給する流路(不図示)が設けられている。セパレータ１６とガス拡散層１２とが接するセパレータ１６の表面には、酸化剤を供給し、水を排出する流路(不図示)が設けられている。 Separators 14 and 16 are disposed outside the gas diffusion layers 10 and 12, respectively. On the surface of the separator 14 where the separator 14 and the gas diffusion layer 10 are in contact, a flow path (not shown) for supplying fuel is provided. On the surface of the separator 16 where the separator 16 and the gas diffusion layer 12 are in contact with each other, a flow path (not shown) for supplying an oxidant and discharging water is provided.
  外部から固体高分子電解質型燃料電池２に供給される燃料（例えば水素）は触媒層６に送られ、触媒層６の触媒の作用により、プロトンと電子とが生成される。このプロトンは、電解質膜４を通り、触媒層８に達する。一方、前記電子は、外部負荷回路(不図示)を通って触媒層８に送られる。触媒層８においては、前記電子と前記プロトンと酸化剤とが結合し、水が生成される。 The fuel (for example, hydrogen) supplied from the outside to the solid polymer electrolyte fuel cell 2 is sent to the catalyst layer 6, and protons and electrons are generated by the action of the catalyst of the catalyst layer 6. This proton passes through the electrolyte membrane 4 and reaches the catalyst layer 8. On the other hand, the electrons are sent to the catalyst layer 8 through an external load circuit (not shown). In the catalyst layer 8, the electrons, the protons, and the oxidizing agent are combined to generate water.
　電解質膜４のプロトンの伝導度は、電解質膜４内の水分の含有量によって変化する。水分含有量が多い場合は、プロトンの伝導度は大きくなり、水分含有量が少ない場合はプロトンの伝導度は小さくなる。 The proton conductivity of the electrolyte membrane 4 varies depending on the water content in the electrolyte membrane 4. When the water content is high, the proton conductivity increases, and when the water content is low, the proton conductivity decreases.
  固体高分子電解質型燃料電池２において、水分の管理は極めて重要である。水管理としては、触媒層８からなるカソードで生成される水の排水管理、及び電解質膜４の保水管理がある。これらの水管理を同時に行う必要がある。 水分 In the solid polymer electrolyte fuel cell 2, the management of moisture is extremely important. Water management includes drainage management of water generated at the cathode formed of the catalyst layer 8 and water retention management of the electrolyte membrane 4. It is necessary to carry out water management at the same time.
  本発明の炭素繊維紙は、炭素繊維紙を構成する炭素繊維同士の間隙で形成される細孔と、一方の面から他方の面に向かって形成される複数の非貫通孔１８とを有する炭素繊維紙である。 The carbon fiber paper of the present invention is a carbon having pores formed by gaps between carbon fibers constituting the carbon fiber paper and a plurality of non-through holes 18 formed from one surface toward the other surface. Fiber paper.
　炭素繊維同士の間隙で形成される細孔の平均孔径は１０～２０μｍで、１２～１８μｍが好ましく、１３～１７μｍがより好ましい。この細孔の平均孔径は、炭素繊維の繊維径、後述する有機高分子の配合量、後述する熱圧縮処理の圧力等を調節することにより制御できる。 The average pore diameter of the pores formed by the gaps between the carbon fibers is 10 to 20 μm, preferably 12 to 18 μm, more preferably 13 to 17 μm. The average pore diameter of the pores can be controlled by adjusting the fiber diameter of the carbon fiber, the amount of the organic polymer described later, the pressure of the thermal compression treatment described later, and the like.
　一方の面から他方の面に向かって形成される複数の非貫通孔１８の平均孔径は、５０～５００μｍで、９０～２５０μｍが好ましく、１１０～２００μｍがより好ましい。非貫通孔１８の孔の深さは、炭素繊維紙の厚みの２０～８０％で、３０～７０％が好ましく、４０～６０％がより好ましい。非貫通孔の孔の深さを上記の範囲に制御することにより、炭素繊維紙を高分子電解質型燃料電池のカソード側のガス拡散層１２に用いる場合、触媒層８で生成する水の排水性及び電解質膜４の保水性を両立させることができる。 The average hole diameter of the plurality of non-through holes 18 formed from one surface to the other surface is 50 to 500 μm, preferably 90 to 250 μm, and more preferably 110 to 200 μm. The depth of the non-through hole 18 is 20 to 80%, preferably 30 to 70%, more preferably 40 to 60% of the thickness of the carbon fiber paper. By controlling the depth of the non-through holes within the above range, when carbon fiber paper is used for the gas diffusion layer 12 on the cathode side of the polymer electrolyte fuel cell, the drainage of water produced in the catalyst layer 8 And the water retention of the electrolyte membrane 4 can be made compatible.
  非貫通孔１８の深さが炭素繊維紙の厚みの２０％未満の場合は、炭素繊維紙内における物質移動性が不足する。従って、この炭素繊維紙をガス拡散層電極８に用いる場合、反応生成水を非貫通孔からスムーズに排出できなくなる。その結果、反応生成水が酸素ガス等の酸化剤の供給を遮断するフラッディングが発生し易くなる。 場合 When the depth of the non-through hole 18 is less than 20% of the thickness of the carbon fiber paper, the mass mobility in the carbon fiber paper is insufficient. Therefore, when this carbon fiber paper is used for the gas diffusion layer electrode 8, the reaction product water cannot be smoothly discharged from the non-through holes. As a result, flooding in which the reaction product water blocks the supply of an oxidizing agent such as oxygen gas is likely to occur.
  非貫通孔１８の深さが、炭素繊維紙の厚みの８０％を超える場合は、炭素繊維紙の非貫通孔の存在する部分と、非貫通孔が存在しない部分との間で物質移動性に斑が生じる。この場合は、炭素繊維紙をガス拡散層に用いる場合、触媒層８に均一にガスを供給することが困難となる。その結果、局所的な電解質膜の乾燥を発生せしめ、最終的には燃料電池の発電性能の低下が生じ易くなる。更に、炭素繊維紙の強度が低下する。 When the depth of the non-through hole 18 exceeds 80% of the thickness of the carbon fiber paper, the mass transferability between the portion of the carbon fiber paper where the non-through hole exists and the portion where the non-through hole does not exist is increased. Spots appear. In this case, when carbon fiber paper is used for the gas diffusion layer, it is difficult to supply gas uniformly to the catalyst layer 8. As a result, local drying of the electrolyte membrane occurs, and eventually the power generation performance of the fuel cell is likely to deteriorate. Furthermore, the strength of the carbon fiber paper is reduced.
  単位面積当りの非貫通孔の数(非貫通孔密度)は１００～１０００個／ｃｍ２が好ましく、３００～５００個／ｃｍ２がより好ましい。 Non number of the through holes (non-through-hole density) is preferably 100 to 1,000 / cm 2 per unit area, more preferably 300-500 amino / cm 2.
  本発明の炭素繊維紙は、繊維状炭素と非繊維状炭素を含む。炭素繊維紙を高分子電解質型燃料電池用ガス拡散層に用いる場合、強度、導電性を高くするため、炭素繊維紙中の繊維状炭素の割合は２０質量％以上で、４０質量％以上が好ましく、６０～９０質量％がより好ましい。炭素繊維紙の厚みは５０～４００μｍが好ましく、８０～３００μｍがより好ましく、１００～２５０μｍが特に好ましい。 炭素 The carbon fiber paper of the present invention contains fibrous carbon and non-fibrous carbon. When carbon fiber paper is used for a gas diffusion layer for a polymer electrolyte fuel cell, the ratio of fibrous carbon in the carbon fiber paper is 20% by mass or more, preferably 40% by mass or more in order to increase strength and conductivity. 60 to 90% by mass is more preferable. The thickness of the carbon fiber paper is preferably 50 to 400 μm, more preferably 80 to 300 μm, and particularly preferably 100 to 250 μm.
  繊維状炭素は、原料の酸化繊維紙中の酸化繊維に由来するものである。非繊維状炭素は、湿式抄紙で原料酸化繊維紙を製造する際に、酸化繊維にバインダーとして混合する有機高分子に由来するものである。 Fibrous carbon is derived from oxidized fibers in the raw oxidized fiber paper. Non-fibrous carbon is derived from an organic polymer that is mixed with the oxidized fiber as a binder when the raw oxidized fiber paper is produced by wet papermaking.
　後述の炭素化処理において、酸化繊維は繊維状炭素になり、有機高分子は非繊維状炭素になる。 In the carbonization treatment described later, the oxidized fiber becomes fibrous carbon, and the organic polymer becomes non-fibrous carbon.
  本発明の炭素繊維紙の製造方法としては、原料酸化繊維紙をレーザー加工によって開孔処理することにより、原料の酸化繊維紙の一方の面から他方の面に向って複数の非貫通孔を形成した酸化繊維紙を得、次いで前記非貫通孔を形成した酸化繊維紙を不活性雰囲気下で、１３００～２５００℃で焼成して炭素化する方法が例示できる。 As a method for producing carbon fiber paper of the present invention, a plurality of non-through holes are formed from one side of the raw oxidized fiber paper to the other side by subjecting the raw oxidized fiber paper to a hole processing by laser processing. An example is a method in which the oxidized fiber paper is obtained and then the oxidized fiber paper in which the non-through holes are formed is baked and carbonized at 1300 to 2500 ° C. in an inert atmosphere.
  又は、酸化繊維紙を、レーザー加工により開孔処理をすることにより、一方の面から他方の面にわたる複数の貫通孔を形成した酸化繊維紙を得、次いで前記貫通孔を形成した酸化繊維紙と、開孔処理を施していない酸化繊維紙とを貼付けた後、この貼付けた酸化繊維紙を上記条件で炭素化する方法がある。 Alternatively, the oxidized fiber paper is subjected to an opening treatment by laser processing to obtain an oxidized fiber paper having a plurality of through holes extending from one surface to the other surface, and then the oxidized fiber paper having the through holes formed therein. There is a method of pasting the oxidized fiber paper that has not been subjected to the opening treatment and then carbonizing the pasted oxidized fiber paper under the above conditions.
  〔原料の酸化繊維紙〕
  本炭素繊維紙の製造用原料の酸化繊維紙は、所定繊維長の酸化繊維と、有機高分子とを混合し、既存の湿式抄紙法にて抄紙することにより製造できる。酸化繊維としては、ポリアクリロニトリル(ＰＡＮ)系、ピッチ系、フェノール系、レーヨン系等の酸化繊維を用いることが出来るが、酸化繊維及び得られる炭素繊維の強度が大きいことから、ＰＡＮ系酸化繊維が好ましい。酸化繊維の平均繊維太さは０．５～５．０dtexが好ましい。酸化繊維の平均繊維長は３～５２ｍｍが好ましく、３～１０ｍｍがより好ましい。 [Oxidized fiber paper as raw material]
Oxidized fiber paper as a raw material for producing the present carbon fiber paper can be produced by mixing oxidized fiber having a predetermined fiber length and an organic polymer, and making paper by an existing wet papermaking method. Oxidized fibers such as polyacrylonitrile (PAN), pitch-based, phenolic, and rayon-based oxidized fibers can be used as the oxidized fibers. However, since the strength of the oxidized fibers and the obtained carbon fibers is high, the PAN-based oxidized fibers are preferable. The average fiber thickness of the oxidized fiber is preferably 0.5 to 5.0 dtex. The average fiber length of the oxidized fiber is preferably 3 to 52 mm, more preferably 3 to 10 mm.
　有機高分子としては、炭素化後の残炭率の高さから、芳香族ポリアミド(アラミド)、フェノール樹脂、ポリイミド、ＰＡＮ等が好適である。有機高分子の形態は、液状、パウダー状、ペレット状、短繊維状、パルプ状等の任意の形態のものが利用できる。 As the organic polymer, aromatic polyamide (aramid), phenol resin, polyimide, PAN, and the like are preferable because of the high residual carbon ratio after carbonization. The organic polymer can be used in any form such as liquid, powder, pellet, short fiber, and pulp.
  〔熱圧縮処理〕
  原料の酸化繊維紙は、均質化や高嵩密度化を目的にして、熱圧縮処理が施されている酸化繊維紙が好ましい。熱圧縮処理は、１００～３５０℃の温度下、圧力０．３０～２０ＭＰａの条件で処理することが好ましい。この処理により、原料の酸化繊維紙の嵩密度は１．０～０．２ｇ／ｃｍ３に制御される。 [Heat compression treatment]
The raw oxidized fiber paper is preferably oxidized fiber paper that has been subjected to heat compression treatment for the purpose of homogenization and high bulk density. The heat compression treatment is preferably carried out at a temperature of 100 to 350 ° C. under a pressure of 0.30 to 20 MPa. By this treatment, the bulk density of the raw oxidized fiber paper is controlled to 1.0 to 0.2 g / cm 3 .
  熱圧縮処理は、例えばカレンダー加工や、プレス加工により行うことができる。 The hot compression process can be performed by, for example, calendaring or pressing.
  この熱圧縮処理の結果、酸化繊維同士は圧縮され、その圧縮により酸化繊維同士の間隙で形成される細孔径は制御される。 酸化 As a result of this thermal compression treatment, the oxidized fibers are compressed, and the pore diameter formed in the gap between the oxidized fibers is controlled by the compression.
  本発明においては、このようにして細孔径を制御した原料の酸化繊維紙に、後述するレーザー加工による開孔処理を行う。 に お い て In the present invention, the raw oxidized fiber paper whose pore diameter is controlled in this way is subjected to a hole opening process by laser processing described later.
  〔開孔処理〕
  上記原料の酸化繊維紙には、レーザー加工装置を用いて開孔処理が施されて、非貫通孔が形成される。非貫通孔の直径は、５４～５４０μｍが好ましい。開孔数は、１００～１００００個／ｃｍ２が好ましい。非貫通孔の深さは酸化繊維紙の厚みの２０～８０％が好ましい。レーザー加工装置としては、ＹＡＧ、ＣＯ２、半導体レーザーなどを利用することが出来る。 [Opening treatment]
The raw oxidized fiber paper is subjected to an opening process using a laser processing apparatus to form non-through holes. The diameter of the non-through hole is preferably 54 to 540 μm. The number of apertures is preferably 100 to 10,000 / cm 2 . The depth of the non-through hole is preferably 20 to 80% of the thickness of the oxidized fiber paper. As the laser processing apparatus, YAG, CO2, a semiconductor laser, or the like can be used.
  レーザー加工条件としては、従来公知の炭酸ガスレーザー等におけるレーザー照射条件を適宜採用できる。炭酸ガスレーザーの場合は、赤外線波長域にある９．３～１０．６μｍの波長が一般的に使用され、エネルギーは４～６０ｍＪが好ましい。 As laser processing conditions, laser irradiation conditions in a conventionally known carbon dioxide gas laser or the like can be appropriately employed. In the case of a carbon dioxide laser, a wavelength of 9.3 to 10.6 μm in the infrared wavelength range is generally used, and the energy is preferably 4 to 60 mJ.
　なお、前述のように酸化繊維紙に貫通孔を形成して多孔酸化繊維紙を得、これに開孔処理をしていない無孔酸化繊維紙を貼合わせても良い。多孔酸化繊維の開孔条件は、前記非貫通孔の開孔条件に準じる。 In addition, as described above, through-holes may be formed in the oxidized fiber paper to obtain a porous oxidized fiber paper, and non-porous oxidized fiber paper that has not been subjected to opening treatment may be bonded to the porous fiber fiber paper. The opening conditions of the porous oxidized fiber conform to the opening conditions of the non-through holes.
　貼り合せ方法としては、前記有機化合物を用いて両者を熱圧着する方法がある。また、前記有機化合物を溶解して製造した接着剤で両者を貼り合せても良い。 As a bonding method, there is a method of thermocompression bonding the two using the organic compound. Moreover, you may bond both together with the adhesive agent which melt | dissolved and manufactured the said organic compound.
  〔炭素化処理〕
  上記酸化繊維紙を、窒素等の不活性ガス雰囲気下、５００℃付近で、好ましくは予備焼成する。その後、窒素等の不活性ガス雰囲気下で１３００～２５００℃で焼成して炭素化し、炭素繊維紙を得る。 [Carbonization treatment]
The oxidized fiber paper is preferably pre-fired at about 500 ° C. in an inert gas atmosphere such as nitrogen. Thereafter, it is carbonized by firing at 1300 to 2500 ° C. in an inert gas atmosphere such as nitrogen to obtain a carbon fiber paper.
  昇温下で炭素化する場合、昇温速度は２００℃／分以下が好ましい。 炭素 When carbonizing at a high temperature, the rate of temperature increase is preferably 200 ° C./min or less.
  以上の製造方法で得られる炭素繊維紙は、一方の面から他方の面に向かって形成した平均孔径が５０～５００μｍの非貫通孔を複数有する。非貫通孔の深さは炭素繊維紙の厚みの２０～８０％である。 The carbon fiber paper obtained by the above manufacturing method has a plurality of non-through holes with an average pore diameter of 50 to 500 μm formed from one side to the other side. The depth of the non-through hole is 20 to 80% of the thickness of the carbon fiber paper.
  この炭素繊維紙は、炭素繊維紙を構成する炭素繊維の間隙で形成される平均細孔径が１０～２０μｍの細孔を有する。この炭素繊維紙は、ＪＩＳ L 1096に規定される通気度が１００００ｍｌ／ｍｉｎ以上であり、その表面に膜状炭化物が形成されておらず、曲げ強さは１０ＭＰａ以上である。 This carbon fiber paper has pores with an average pore diameter of 10 to 20 μm formed by the gaps between the carbon fibers constituting the carbon fiber paper. This carbon fiber paper has an air permeability defined by JIS L 1096 of 10,000 ml / min or more, no film-like carbide is formed on the surface, and a bending strength of 10 MPa or more.
  更に、この炭素繊維紙は、厚さが５０～４００μｍ、目付が２０～１８０ｇ／ｍ２、嵩密度が０．２～０．６ｇ／ｃｍ３である。 Further, the carbon fiber paper has a thickness of 50 to 400 μm, a basis weight of 20 to 180 g / m 2 , and a bulk density of 0.2 to 0.6 g / cm 3 .
  以下、実施例により本発明を更に具体的に説明するが、本発明はこれら実施例に限定されるものではない。なお、操作条件の評価、各物性の測定は次の方法によった。 Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, evaluation of operation conditions and measurement of each physical property were based on the following methods.
  〔酸化繊維紙、炭素繊維紙の細孔径〕
  パームポロメーター[ＰＭＩ(Ｐｏｒｏｕｓ　Ｍａｔｅｒｉａｌ，Ｉｎｃ．)社製：商品名ＣＦＰ－１１００ＡＥＸ]を用い、酸化繊維紙、炭素繊維紙の細孔分布を測定した。得られた細孔分布を用いて体積平均細孔径を求めた。 [Pore diameter of oxidized fiber paper and carbon fiber paper]
The pore distribution of oxidized fiber paper and carbon fiber paper was measured using a palm porometer [manufactured by PMI (Porous Material, Inc.): trade name CFP-1100AEX]. Using the obtained pore distribution, the volume average pore diameter was determined.
  〔酸化繊維紙、炭素繊維紙の非貫通孔〕
  デジタルマイクロスコープ(ＫＥＹＥＮＣＥ社製：商品名ＶＨ－８０００Ｃ)を用い、酸化繊維紙、炭素繊維紙の非貫通孔の諸寸法を測定した。これらの測定値から、前述の算出方法により、平均非貫通孔径、非貫通孔密度を求めた。 [Non-through holes in oxidized fiber paper and carbon fiber paper]
Using a digital microscope (manufactured by KEYENCE, trade name: VH-8000C), various dimensions of non-through holes of oxidized fiber paper and carbon fiber paper were measured. From these measured values, the average non-through hole diameter and non-through hole density were determined by the above-described calculation method.
  〔酸化繊維の比重〕
  比重は、アルキメデス法(溶媒アセトン)により測定した。 [Specific gravity of oxidized fiber]
Specific gravity was measured by the Archimedes method (solvent acetone).
  〔酸化繊維紙、炭素繊維紙の厚さ〕
  酸化繊維紙、炭素繊維紙に直径５ｍｍの円盤状の圧板で荷重１．２Ｎを負荷したときの厚さを測定した。 [Thickness of oxidized fiber paper and carbon fiber paper]
The thickness of the oxidized fiber paper and carbon fiber paper when a load of 1.2 N was applied with a disk-shaped pressure plate having a diameter of 5 mm was measured.
  〔酸化繊維紙、炭素繊維紙の目付〕
  １００ｍｍ角の酸化繊維紙、炭素繊維紙を１２０℃、１時間乾燥させた後、質量を測定し、単位面積当たりの質量を算出した。 [Oxidized fiber paper, carbon fiber paper weight]
A 100 mm square oxidized fiber paper and carbon fiber paper were dried at 120 ° C. for 1 hour, and then the mass was measured to calculate the mass per unit area.
  〔酸化繊維紙、炭素繊維紙の嵩密度〕
  上記条件により測定した厚さ及び目付のデータを用いて嵩密度を算出した。 [Bulk density of oxidized fiber paper and carbon fiber paper]
The bulk density was calculated using the thickness and basis weight data measured under the above conditions.
  〔実施例１〕
  酸化繊維としてポリアクリロニトリル(ＰＡＮ)系酸化繊維(平均繊維太さ２．２ｄｔｅｘ、平均繊維長５ｍｍ、比重１．４２)と、有機高分子としてアラミドファイブリッド(平均繊維長１．２ｍｍ、デュポン社製)と、ポリエチレンテレフタレート（ＰＥＴ）繊維(平均繊維太さ２．５ｄｔｅｘ、平均繊維長５ｍｍ)とを、配合比が６５／１５／２０質量％となるように混合した。この混合物を、湿式抄紙し、原料の酸化繊維紙を得た。 [Example 1]
Polyacrylonitrile (PAN) oxidized fiber (average fiber thickness 2.2 dtex, average fiber length 5 mm, specific gravity 1.42) as oxidized fiber, and aramid fibrid (average fiber length 1.2 mm, manufactured by DuPont) as organic polymer ) And polyethylene terephthalate (PET) fibers (average fiber thickness 2.5 dtex, average fiber length 5 mm) were mixed so that the blending ratio was 65/15/20 mass%. This mixture was subjected to wet paper making to obtain a raw oxidized fiber paper.
　原料の酸化繊維紙を温度１８０℃、圧力８．５ＭＰａの条件下で６０秒間圧縮処理することにより、目付１４７ｇ／ｍ２、厚さ３２０μｍ、嵩密度０．４６ｇ／ｃｍ３、酸化繊維同士の間隙で形成される細孔の平均孔径１７μｍの酸化繊維紙を得た。 By compressing the raw oxidized fiber paper for 60 seconds under the conditions of a temperature of 180 ° C. and a pressure of 8.5 MPa, the basis weight is 147 g / m 2 , the thickness is 320 μm, the bulk density is 0.46 g / cm 3 , and the gap between the oxidized fibers Oxidized fiber paper having an average pore diameter of 17 μm was obtained.
  この酸化繊維紙に、レーザー加工装置で開孔処理を施し、直径２２０μｍ、深さ２４０μｍ(酸化繊維紙の厚みの７５％)、非貫通孔密度３２０個／ｃｍ２の非貫通孔を有する酸化繊維紙を得た。 The oxidized fiber paper is subjected to a hole opening process by a laser processing apparatus, and the oxidized fiber has non-through holes having a diameter of 220 μm, a depth of 240 μm (75% of the thickness of the oxidized fiber paper), and a non-through hole density of 320 / cm 2. I got paper.
　その後、この酸化繊維紙を窒素ガス雰囲気下にて５００℃で１０分間、その後２０００℃で１０分間焼成した。目付７５ｇ／ｍ２、厚さ２００μｍ、嵩密度０．３７５ｇ／ｃｍ３の炭素繊維紙が得られた。 Thereafter, the oxidized fiber paper was fired at 500 ° C. for 10 minutes in a nitrogen gas atmosphere, and then at 2000 ° C. for 10 minutes. A carbon fiber paper having a basis weight of 75 g / m 2 , a thickness of 200 μm, and a bulk density of 0.375 g / cm 3 was obtained.
  〔実施例２〕
  酸化繊維紙の非貫通孔の深さを８０μｍ(酸化繊維紙の厚みの２５％)にしたこと以外は、実施例１と同様にして炭素繊維紙を得た。表１に示すように、この炭素繊維紙は、非貫通孔の直径が２０２μｍ、非貫通孔の深さが５０μｍ(炭素繊維紙の厚みの２５％)、非貫通孔密度が４００個／ｃｍ２、繊維同士の間隙で形成される細孔の平均孔径が１５μｍであった。 [Example 2]
Carbon fiber paper was obtained in the same manner as in Example 1 except that the depth of the non-through hole of the oxidized fiber paper was 80 μm (25% of the thickness of the oxidized fiber paper). As shown in Table 1, this carbon fiber paper has a non-through hole diameter of 202 μm, a non-through hole depth of 50 μm (25% of the thickness of the carbon fiber paper), and a non-through hole density of 400 holes / cm 2. The average pore diameter of the pores formed by the gaps between the fibers was 15 μm.
  〔実施例３〕
  目付７２ｇ／ｍ２、厚さ１６０μｍ、嵩密度０．４５ｇ／ｃｍ３、繊維同士の間隙で形成される細孔の平均孔径１７μｍの酸化繊維紙に、レーザー加工装置で開孔処理を施し、直径２２０μｍ、３２０個／ｃｍ２の貫通孔を有する多孔酸化繊維紙を得た。この多孔酸化繊維紙に、目付７２ｇ／ｍ２、厚さ１６０μｍ、嵩密度０．４５ｇ／ｃｍ３、繊維同士の間隙で形成される細孔の平均孔径１７μｍの無孔酸化繊維紙を張り合わせて、貼付型酸化繊維紙を得た。この貼付型酸化繊維紙を、実施例１と同様の条件で焼成して炭素化させて、目付７５ｇ／ｍ２、厚さ２００μｍ、嵩密度０．３７５ｇ／ｃｍ３の炭素繊維紙を得た。 Example 3
An oxidized fiber paper having a basis weight of 72 g / m 2 , a thickness of 160 μm, a bulk density of 0.45 g / cm 3 , and an average pore diameter of 17 μm formed by gaps between fibers is subjected to a hole opening treatment with a laser processing apparatus, and the diameter A porous oxidized fiber paper having through holes of 220 μm and 320 pieces / cm 2 was obtained. To this porous oxidized fiber paper, non-porous oxidized fiber paper having a basis weight of 72 g / m 2 , a thickness of 160 μm, a bulk density of 0.45 g / cm 3 , and an average pore diameter of 17 μm of pores formed by the gaps between fibers was laminated, A patch-type oxidized fiber paper was obtained. This sticky oxidized fiber paper was baked and carbonized under the same conditions as in Example 1 to obtain a carbon fiber paper having a basis weight of 75 g / m 2 , a thickness of 200 μm, and a bulk density of 0.375 g / cm 3 .
  この炭素繊維紙は、表１に示すように、非貫通孔の直径が２０２μｍ、非貫通孔の深さが１００μｍ(炭素繊維紙の厚みの５０％)、非貫通孔密度が４００個／ｃｍ２、繊維同士の間隙で形成される細孔の平均孔径が１５μｍであった。 As shown in Table 1, this carbon fiber paper has a non-through hole diameter of 202 μm, a non-through hole depth of 100 μm (50% of the thickness of the carbon fiber paper), and a non-through hole density of 400 holes / cm 2. The average pore diameter of the pores formed by the gaps between the fibers was 15 μm.
　  〔実施例４～９〕
　実施例１と同様に操作して、表１に記載の炭素繊維紙を得た。 [Examples 4 to 9]
The carbon fiber paper shown in Table 1 was obtained by operating in the same manner as in Example 1.
  〔比較例１〕
  酸化繊維紙に開孔処理を施さなかった以外は実施例１と同様に操作して炭素繊維紙を得た。この炭素繊維紙には、直径５０μｍ以上の貫通孔及び非貫通孔が無いことが確認された。繊維同士の間隙で形成される細孔の平均孔径は、１５μｍであった。 [Comparative Example 1]
A carbon fiber paper was obtained in the same manner as in Example 1 except that the oxidized fiber paper was not subjected to the hole opening treatment. This carbon fiber paper was confirmed to have no through holes and non-through holes with a diameter of 50 μm or more. The average pore diameter of the pores formed by the gaps between the fibers was 15 μm.
  〔比較例２〕
  酸化繊維紙の非貫通孔の深さを４０μｍ(酸化繊維紙の厚みの１２．５％)としたこと以外は、実施例１と同様に操作して炭素繊維紙を得た。 [Comparative Example 2]
Carbon fiber paper was obtained in the same manner as in Example 1 except that the depth of the non-through hole of the oxidized fiber paper was 40 μm (12.5% of the thickness of the oxidized fiber paper).
　表１に示すように、この炭素繊維紙は、非貫通孔の直径が２０２μｍ、非貫通孔の深さが２５μｍ(炭素繊維紙の厚みの１２．５％)、非貫通孔密度が４００個／ｃｍ２、繊維同士の間隙で形成される細孔の平均孔径が１５μｍであった。 As shown in Table 1, this carbon fiber paper has a non-through hole diameter of 202 μm, a non-through hole depth of 25 μm (12.5% of the thickness of the carbon fiber paper), and a non-through hole density of 400 / The average pore diameter of the pores formed by cm 2 and the gap between the fibers was 15 μm.
  〔比較例３〕
  酸化繊維紙の非貫通孔の深さを２８０μｍ(酸化繊維紙の厚みの８７．５％)としたこと以外は、実施例１と同様にして炭素繊維紙を得た。 [Comparative Example 3]
A carbon fiber paper was obtained in the same manner as in Example 1 except that the depth of the non-through hole of the oxidized fiber paper was 280 μm (87.5% of the thickness of the oxidized fiber paper).
　表１に示すように、この炭素繊維紙は、非貫通孔の直径が２０２μｍ、非貫通孔の深さが１７５μｍ(炭素繊維紙の厚みの８７．５％)、非貫通孔密度が４００個／ｃｍ２、繊維同士の間隙で形成される細孔の平均孔径が１５μｍであった。 As shown in Table 1, this carbon fiber paper has a non-through hole diameter of 202 μm, a non-through hole depth of 175 μm (87.5% of the thickness of the carbon fiber paper), and a non-through hole density of 400 / The average pore diameter of the pores formed by cm 2 and the gap between the fibers was 15 μm.
  〔比較例４〕
  酸化繊維紙の開孔処理において孔を貫通させた以外は、実施例１と同様にして炭素繊維紙を得た。表２に示すように、この炭素繊維紙は、貫通孔の直径が２０２μｍ、貫通孔の深さが２０２μｍ(炭素繊維紙の厚みの１００％)、貫通孔の表面密度が４００個／ｃｍ２、繊維同士の間隙で形成される細孔の平均孔径が１５μｍであった。 [Comparative Example 4]
Carbon fiber paper was obtained in the same manner as in Example 1 except that the hole was penetrated in the opening process of the oxidized fiber paper. As shown in Table 2, the carbon fiber paper has a through hole diameter of 202 μm, a through hole depth of 202 μm (100% of the thickness of the carbon fiber paper), and a surface density of the through holes of 400 pieces / cm 2 . The average pore diameter of the pores formed by the gaps between the fibers was 15 μm.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
  〔評価例〕
  実施例１～３で得られた炭素繊維紙を用いて、固体高分子電解質型燃料電池用ガス拡散層を作製した。これらのガス拡散層を組込んだ燃料電池(セル)を、表３に示す高加湿条件下、及び低加湿条件下において発電させることにより、ガス拡散層の評価テストを行った。表１、２に最高到達電流密度を記載した。実施例１～３で得られた炭素繊維紙は、高加湿条件下及び低加湿条件下の何れの場合にも、高い電流密度において、電圧の低下が見られなかった。即ち、広い電流密度域で高い電池性能が維持できた。 [Evaluation example]
Using the carbon fiber paper obtained in Examples 1 to 3, a gas diffusion layer for a solid polymer electrolyte fuel cell was produced. A fuel cell (cell) incorporating these gas diffusion layers was subjected to an evaluation test of the gas diffusion layer by generating power under the high and low humidification conditions shown in Table 3. Tables 1 and 2 list the maximum reached current density. The carbon fiber papers obtained in Examples 1 to 3 did not show a decrease in voltage at a high current density under both high and low humidification conditions. That is, high battery performance could be maintained in a wide current density range.
　実施例４～９で得られた炭素繊維紙を、同様の方法で評価した。表１、２に最高到達電流密度を記載した。実施例４～９で得られた炭素繊維紙は、高加湿条件下及び低加湿条件下の何れの場合にも、０．７Ａ／ｃｍ２の高い電流密度が得られた。 The carbon fiber paper obtained in Examples 4 to 9 was evaluated in the same manner. Tables 1 and 2 list the maximum reached current density. The carbon fiber papers obtained in Examples 4 to 9 had a high current density of 0.7 A / cm 2 under both high and low humidification conditions.
  比較例１～２で得られた炭素繊維紙を用いて、同様の評価テストを行った。表１、２に最高到達電流密度を記載した。何れの炭素繊維紙についても、高加湿条件下の場合、低い電流密度領域において、出力電圧の低下が見られ、電池性能は低いものであった。その原因は、反応生成水の排出が不十分の点にあった。 A similar evaluation test was performed using the carbon fiber paper obtained in Comparative Examples 1 and 2. Tables 1 and 2 list the maximum reached current density. For any carbon fiber paper, under high humidification conditions, the output voltage decreased in a low current density region, and the battery performance was low. The cause was inadequate discharge of reaction product water.
  比較例３～４で得られた炭素繊維紙を用いて、同様の評価テストを行った。表１、２に最高到達電流密度を記載した。何れの炭素繊維紙についても、低加湿条件下の場合、低い電流密度領域において電圧の低下が見られ、電池性能は低いものであった。その原因は、電解質膜の乾燥による膜抵抗の増加にあると推定される。 同 様 Similar evaluation tests were performed using the carbon fiber paper obtained in Comparative Examples 3-4. Tables 1 and 2 list the maximum reached current density. For any of the carbon fiber papers, under low humidification conditions, a voltage drop was observed in a low current density region, and the battery performance was low. The cause is estimated to be an increase in membrane resistance due to drying of the electrolyte membrane.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003

Claims (5)

  1. 炭素繊維紙を構成する炭素繊維同士の間隙で形成される平均孔径が１０～２０μｍの細孔と、一方の面から他方の面に向かって形成される平均孔径が５０～５００μｍの複数の非貫通孔とを有する炭素繊維紙であって、非貫通孔の深さが炭素繊維紙の厚みの２０～８０％であり、単位面積当りの非貫通孔の数が１００～１０００個／ｃｍ２であり、厚みが５０～４００μｍである固体高分子電解質型燃料電池ガス拡散層用炭素繊維紙。 A pore having an average pore diameter of 10 to 20 μm formed by a gap between carbon fibers constituting the carbon fiber paper and a plurality of non-penetrations having an average pore diameter of 50 to 500 μm formed from one surface to the other surface Carbon fiber paper having holes, the depth of the non-through holes being 20 to 80% of the thickness of the carbon fiber paper, and the number of non-through holes per unit area being 100 to 1000 / cm 2 A carbon fiber paper for a solid polymer electrolyte fuel cell gas diffusion layer having a thickness of 50 to 400 μm.
  2. 炭素繊維紙が、繊維状炭素と非繊維状炭素とを含み、炭素繊維紙中の繊維状炭素の割合が２０質量％以上である請求項１に記載の炭素繊維紙。 The carbon fiber paper according to claim 1, wherein the carbon fiber paper contains fibrous carbon and non-fibrous carbon, and the proportion of the fibrous carbon in the carbon fiber paper is 20% by mass or more.
  3. カソード側のガス拡散層に用いる請求項１に記載の炭素繊維紙。 The carbon fiber paper according to claim 1, which is used for a gas diffusion layer on the cathode side.
  4. 酸化繊維紙にレーザー加工をすることにより、酸化繊維紙の一方の面から他方の面に向かう非貫通孔を複数形成した酸化繊維紙を得、次いで前記非貫通孔を形成した酸化繊維紙を不活性雰囲気下、１３００～２５００℃の温度で焼成することを特徴とする、炭素繊維紙を構成する炭素繊維同士の間隙で形成される平均孔径が１０～２０μｍの細孔と、一方の面から他方の面に向かって形成される平均孔径が５０～５００μｍの複数の非貫通孔とを有する炭素繊維紙であって、非貫通孔の深さが炭素繊維紙の厚みの２０～８０％であり、単位面積当りの非貫通孔の数が１００～１０００個／ｃｍ２であり、厚みが５０～４００μｍである固体高分子電解質型燃料電池ガス拡散層用炭素繊維紙の製造方法。 By performing laser processing on the oxidized fiber paper, an oxidized fiber paper having a plurality of non-through holes from one surface of the oxidized fiber paper to the other surface is obtained, and then the oxidized fiber paper having the non-through holes formed therein is not used. A pore having an average pore diameter of 10 to 20 μm formed by a gap between carbon fibers constituting carbon fiber paper, characterized by firing at a temperature of 1300 to 2500 ° C. in an active atmosphere, and from one surface to the other A carbon fiber paper having a plurality of non-through holes with an average pore diameter of 50 to 500 μm formed toward the surface, wherein the depth of the non-through holes is 20 to 80% of the thickness of the carbon fiber paper, A method for producing a carbon fiber paper for a solid polymer electrolyte fuel cell gas diffusion layer, wherein the number of non-through holes per unit area is 100 to 1000 holes / cm 2 and the thickness is 50 to 400 μm.
  5. 酸化繊維紙にレーザー加工することにより、一方の面から他方の面にわたる貫通孔を複数形成した酸化繊維紙を得、次いで前記貫通孔を形成した酸化繊維紙と、開孔処理を施していない酸化繊維紙とを貼付けることにより、貼付けた酸化繊維紙の一方の面から他方の面に向かう非貫通孔を複数形成した貼付型酸化繊維紙を得、次いで前記貼付型酸化繊維紙を不活性雰囲気下、１３００～２５００℃の温度で焼成することを特徴とする、炭素繊維紙を構成する炭素繊維同士の間隙で形成される平均孔径が１０～２０μｍの細孔と、一方の面から他方の面に向かって形成される平均孔径が５０～５００μｍの複数の非貫通孔とを有する炭素繊維紙であって、非貫通孔の深さが炭素繊維紙の厚みの２０～８０％であり、単位面積当りの非貫通孔の数が１００～１０００個／ｃｍ２であり、厚みが５０～４００μｍである固体高分子電解質型燃料電池ガス拡散層用炭素繊維紙の製造方法。 Laser processing is performed on the oxidized fiber paper to obtain an oxidized fiber paper in which a plurality of through holes extending from one surface to the other surface are formed, and then the oxidized fiber paper in which the through holes are formed and an oxidation that has not been subjected to the opening process. By sticking the fiber paper, a paste type oxidized fiber paper having a plurality of non-through holes formed from one side to the other side of the pasted oxidized fiber paper is obtained, and then the paste type oxidized fiber paper is in an inert atmosphere. Lower pores having an average pore diameter of 10 to 20 μm formed by gaps between carbon fibers constituting carbon fiber paper, characterized by firing at a temperature of 1300 to 2500 ° C., and from one side to the other side Carbon fiber paper having a plurality of non-through holes with an average pore diameter of 50 to 500 μm formed toward the surface, the depth of the non-through holes being 20 to 80% of the thickness of the carbon fiber paper, and a unit area The number of non-through holes per A method for producing a carbon fiber paper for a solid polymer electrolyte fuel cell gas diffusion layer having a thickness of 100 to 1000 / cm 2 and a thickness of 50 to 400 μm.
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CN111682227A (en) * 2020-07-06 2020-09-18 山东交通学院 Preparation method of diffusion layer for fuel cell

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