Carbon fiber fabrics, fuel cells, liquid electrolytic devices, redox flow batteries, planar heaters, and mobile bodies

Abstract

The object of the present invention is to provide a carbon fiber fabric, fuel cell, liquid electrolytic device, redox flow battery, planar heater, and mobile body that achieve both conductivity, tensile strength, and spring properties. [Solution] The carbon fiber fabric according to the present invention is a carbon fiber fabric formed by interweaving warp threads and weft threads, wherein the warp threads and / or weft threads are composed of spun yarns made of carbon fibers with a length of 90 mm or more and 230 mm or less.

Description

Technical Field

[0001] The present invention relates to a carbon fiber fabric used for a gas diffusion layer used in a fuel cell, a liquid electrolysis device, or a redox flow battery, and particularly to a carbon fiber fabric suitable for a gas diffusion layer of a solid polymer fuel cell used as a power source for a moving body such as a fuel cell vehicle or a ship.

Background Art

[0002] A fuel cell is a kind of power generation device that extracts electrical energy by electrochemically oxidizing fuels such as hydrogen and methanol, and has recently attracted attention as a clean energy supply source. Among them, the solid polymer fuel cell has a relatively low standard operating temperature of around 100°C and a high energy density, so it is expected to have a wide range of applications as a power generation device for relatively small-scale distributed power generation facilities, moving bodies such as fuel cell vehicles and ships.

[0003] The basic structure of a solid polymer fuel cell consists of a polymer electrolyte membrane, catalyst layers formed on both sides of the polymer electrolyte membrane, a gas diffusion layer formed outside the catalyst layer, and two separators sandwiching them.

[0004] The gas diffusion layer is required to have high gas diffusibility for diffusing the gas supplied from the separator to the catalyst, high drainage for discharging the water generated during the electrochemical reaction to the separator, and high conductivity for extracting the generated current. As a material having the above characteristics, a porous carbon sheet is generally used as the gas diffusion layer. Specific examples of the porous carbon sheet include conductive porous substrates such as carbon felt, carbon paper, and carbon fiber fabric made of carbon fiber. Among them, carbon paper, which is a substrate obtained by binding a carbon fiber paper body with a carbonized resin, is preferable in terms of mechanical strength, and is generally used because it has excellent characteristics of absorbing dimensional changes in the thickness direction due to swelling and shrinkage of the electrolyte membrane, that is, "springiness".

[0005] However, because carbon paper has a structure in which carbon fibers are bound together with a binder, conductivity in the thickness direction requires passing through multiple binder-carbon fiber spaces, resulting in low conductivity in that direction. Improving the conductivity of the gas diffusion layer is also a challenge in order to improve the performance of fuel cells, so studies are being conducted on using carbon fiber fabrics, which have excellent conductivity in the thickness direction, as a substitute for carbon paper in the gas diffusion layer.

[0006] For example, Patent Document 1 describes a technique for producing a carbon fiber fabric with minimal thickness variation and appropriate rigidity by first treating acrylic spun yarn as flame-resistant fibers, then weaving it into a fabric, pressing it, carbonizing or graphitizing it, and finally applying a binder.

[0007] Furthermore, Patent Document 2 describes a technique for producing a carbon fiber fabric of a thickness suitable for a gas diffusion layer by weaving thin acrylic fibers and then flame-retarding and carbonizing the fabric itself. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2004-100102 [Patent Document 2] Japanese Patent Publication No. 2019-71292 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, the carbon fiber fabric disclosed in Patent Document 1 is insufficient to reduce contact resistance with CCM (Catalyst Coated Membrane) and separators. In contrast, the carbon fiber fabric disclosed in Patent Document 2 is sufficiently thin and has excellent conductivity, but it has the problem of insufficient tensile strength and springiness unless it undergoes a hardening treatment.

[0010] Therefore, the present invention has been made in view of the above, and aims to provide a carbon fiber fabric, fuel cell, liquid electrolytic device, redox flow battery, planar heater, and mobile body that are excellent in conductivity, tensile strength, and springiness. [Means for solving the problem]

[0011] To solve the above problems, the present invention employs the following means. [1] A carbon fiber fabric formed by interweaving warp and weft threads, wherein the warp and / or weft threads are composed of spun yarns made of carbon fibers with a length of 90 mm or more and 230 mm or less. [2] The carbon fiber fabric according to [1], wherein the warp and / or weft threads are spun yarns made of carbon fibers with a length of 90 mm or more and 120 mm or less. [3] The carbon fiber fabric according to [1] or [2], wherein the twist angle of the spun yarn is 5° or more and 35° or less. [4] A carbon fiber fabric according to any of [1] to [3], wherein the warp and / or weft are double-ply yarns. [5] A carbon fiber fabric as described in any of [1] to [4], wherein the weave structure is plain weave or twill weave. [6] A carbon fiber fabric as described in any of [1] to [5], wherein the thickness when pressurized at 1 MPa is 50 μm or more and 150 μm or less. [7] A carbon fiber fabric according to any one of [1] to [6], wherein the diameter of the carbon fibers is 3 μm or more and 10 μm or less. [8] A carbon fiber fabric according to any one of [1] to [7], wherein the number of carbon fibers contained in the cross-section of the spun yarn is 50 or more and 250 or less per single yarn. [9] A carbon fiber fabric as described in any of [1] to [8], wherein the opening ratio is 5% or more and 75% or less. A fuel cell having a carbon fiber fabric as described in any of

[10] [1] to [9]. A liquid electrolytic apparatus having a carbon fiber fabric as described in any of

[11] [1] to [9]. A redox flow battery having a carbon fiber fabric as described in any of

[12] [1] to [9]. A planar heater having the carbon fiber fabric according to any one of

[13] [1] to [9].

[14] A moving body equipped with the fuel cell according to

[10] .

Advantages of the Invention

[0012] According to the present invention, a carbon fiber fabric excellent in conductivity, tensile strength, and springiness can be obtained.

Brief Description of the Drawings

[0013] [Figure 1] FIG. 1 is a diagram schematically showing the carbon fiber fabric according to the present invention. [Figure 2] FIG. 2 is a micrograph of the carbon fiber fabric according to Example 3 of the present invention. [Figure 3] FIG. 3 is a diagram showing a tensile test piece.

Modes for Carrying Out the Invention

[0014] Hereinafter, embodiments of the carbon fiber fabric according to the present invention will be described in detail based on the drawings. Note that the present invention is not limited by this embodiment. Also, the individual embodiments of the present invention are not independent, and they can be appropriately implemented in combination.

[0015] (Embodiment) FIG. 1 is a diagram schematically showing the carbon fiber fabric according to the present invention. The carbon fiber fabric of the present invention is formed by interweaving warp and weft threads. Here, the warp and / or weft threads are spun yarns. The spun yarns are composed of carbon fibers having a length of 90 mm or more and 230 mm or less. When both the warp and weft threads are spun yarns, any one of the spun yarns may be composed of carbon fibers having a length of 90 mm or more and 230 mm or less. When the length of the carbon fiber is 90 mm or more, a spun yarn having sufficient tensile strength can be obtained even when using a fine-count yarn such as 130 metric count yarn as a raw material. Here, the "length" of the carbon fiber refers to the length of the single fiber of the carbon fiber.

[0016] The length of the carbon fiber is preferably long, but if it is too long, it is difficult to stably produce the raw material fiber, resulting in high costs. The length of the carbon fiber is 230 mm or less, and when it is 120 mm or less, it is preferable because it can be produced at low cost. Note that it is important that the spun yarn is substantially composed of carbon fibers with a length of 90 mm or more and 230 mm or less. That is, it is not necessary that all the fibers constituting the spun yarn are carbon fibers with a length strictly within the range of 90 mm or more and 230 mm or less. In the present invention, "the spun yarn is composed of carbon fibers with a length of 90 mm or more and 230 mm or less" means that 90% or more of the fibers constituting the spun yarn are carbon fibers with a length of 90 mm or more and 230 mm or less. Therefore, as a component of the spun yarn, fibers other than carbon fibers or carbon fibers with a length outside the above range may be included in less than 10% of the whole.

[0017] In the present invention, the diameter of the carbon fiber constituting the spun yarn is preferably 3 μm or more and 10 μm or less. When the diameter of the carbon fiber is 10 μm or less, the thickness of the carbon fiber fabric can be reduced, and a carbon fiber fabric preferable for fuel cell applications can be obtained. Further, when the diameter of the carbon fiber is less than 3 μm, the strength and productivity of the carbon fiber fabric may deteriorate due to the small diameter.

[0018] The twist angle of the spun yarn constituting the carbon fiber fabric of the present invention is preferably 5° or more and 35° or less. Here, the twist angle is the angle (crossing angle) formed by the single fiber with respect to the center line of the spun yarn (a straight line extending in the stretching direction). This will be described with reference to FIG. 1. In FIG. 1, θ1 indicates the twist angle of the spun yarn constituting the warp. That is, θ1 indicates the angle formed by the center line of the spun yarn constituting the warp and the single fiber constituting the spun yarn. Similarly, θ2 indicates the twist angle of the spun yarn constituting the weft. When the twist angle is 5° or more, the springiness of the carbon fiber fabric is improved. When the twist angle exceeds 35°, there is a risk of generating minute cracks inside due to twist tightening caused by flame resistance or heat shrinkage during carbonization. When internal defects exist, single fiber breakage gradually occurs due to repeated compression, deteriorating the conductivity. It is more preferable that the twist angle is 30° or less because internal defects are less likely to occur.

[0019] The spun yarns (warp and / or weft) constituting the carbon fiber fabric of the present invention may be single yarns or double yarns, but double yarns are preferred because they increase the tensile strength and springiness of the carbon fiber fabric. A double yarn is a yarn made by twisting two single yarns together. For example, if a double yarn is made using a 130-meter single yarn, it is written as 2 / 130. If single yarns are used as they are, it is written as 1 / 130. Even in the case of double yarns, it is preferable that the twist angle defined for double yarns is within the range described above.

[0020] The spun yarn constituting the carbon fiber fabric of the present invention preferably contains 50 to 250 carbon fibers per single yarn in its cross-section. If the spun yarn is a double yarn, it is preferable that each single yarn constituting the double yarn is composed of 50 to 250 carbon fibers. To make the carbon fiber fabric thinner, it is preferable that the number of carbon fibers constituting the spun yarn be 250 or less. If the number of carbon fibers constituting the spun yarn is 150 or less, the thickness of the carbon fiber fabric can be further reduced, resulting in a carbon fiber fabric that is more suitable for fuel cell applications. If the number of carbon fibers constituting the spun yarn is less than 50, the strength and productivity of the carbon fiber fabric may deteriorate.

[0021] The carbon fiber fabric can be woven in plain weave, twill weave, or other patterns, but a twill weave is preferred because it improves springiness. When the carbon fiber fabric is used as a gas diffusion layer for fuel cells, a twill weave is also preferred because it improves in-plane gas diffusion under pressure.

[0022] Since the carbon fiber fabric is used as an electrode under pressure, it is preferable that its thickness when pressurized at a surface pressure of 1 MPa is between 50 μm and 150 μm. A thickness of 150 μm or less when pressurized at a surface pressure of 1 MPa is preferable because it provides excellent conductivity and allows for a reduction in the size of the fuel cell unit. On the other hand, if the thickness is less than 50 μm, the strength of the carbon fiber fabric and the gas diffusion within the surface may deteriorate.

[0023] Furthermore, the carbon fiber fabric of the present invention preferably has an opening ratio of 5% or more and 75% or less. An opening ratio of 5% or more is preferable because it provides a carbon fiber fabric with excellent gas diffusion in the direction perpendicular to the surface. If the opening ratio of the carbon fiber fabric exceeds 75%, it may become difficult to apply the microporous layer coating to one side of the carbon fiber fabric. Here, the opening ratio of the carbon fiber fabric is the value defined by the following formula (1), where Tp is the warp pitch, Yp is the weft pitch, Tw is the warp width, and Yw is the weft width. Opening ratio [%]=(Tp-Tw)×(Yp-Yw) / Tp / Yp×100 ...(1)

[0024] Next, a preferred method for obtaining the carbon fiber fabric of the present invention will be described in detail. However, the present invention is not limited to the following description, and any description of preferred embodiments within each description can also be interpreted as a description of the present invention as a broader concept.

[0025] <Spinning Process> In the spinning process of carbon fiber fabrics, long-fiber slivers can be used, which are produced using fibers made from natural cellulose (cotton, bamboo fiber, etc.), regenerated cellulose (rayon, acetate), polyacrylonitrile-based, pitch-based, polynosic-based, phenolic resin-based, poly(p-phenylene terephthalamide), or mixtures thereof as starting materials. Acrylic fibers, mainly composed of polyacrylonitrile, are desirable as starting materials because they are stable in terms of strength. Long-fiber slivers are obtained by cutting a tow, which is a bundle of filaments, using methods such as direct spinning, parlock spinning, or stapling. Spun yarn using long-fiber slivers can be produced in the following order, for example: drawing, roving, and finishing. The purpose of the drawing process is to align multiple slivers, perform drafting and doubling, reduce long-period thickness variations in the slivers, and further parallelize and straighten the fibers. The roving process involves drawing the sliver thin and increasing the parallelism of the fibers, creating a roving package that is easy to handle on the spinning machine. The spinning process involves drafting the roving to a specified thickness and simultaneously adding twist to the fiber bundle to give it strength, thereby producing spun yarn.

[0026] <Weaving process> In the weaving process, spun yarn is used to produce a fabric. In this invention, it is important that at least one of the warp or weft threads constituting the fabric is a spun yarn containing long fibers obtained by the aforementioned spinning process in order to improve the strength and springiness of the carbon fiber fabric. It is preferable that the spun yarn is a double yarn, as this further improves the springiness. Examples of weaving methods include plain weave, twill weave, or satin weave, but twill weave is preferred in order to improve the springiness of the carbon fiber fabric.

[0027] <Flame resistance process> The fabric obtained in the weaving process is heat-treated in air using a batch-type or continuous-type heating furnace. By heat-treating at 200-300°C, flame-resistant fabric is obtained. When flame-resistant fibers or carbon fibers are used as weaving materials, it is necessary to use relatively thick threads, and the electrical resistance in the thickness direction of the carbon fiber fabric remains high. In this invention, by first creating a thin fabric from acrylic fibers and then performing the flame-retardant and carbonization processes in a planar manner, the total energy cost can be reduced compared to weaving flame-resistant fibers or carbon fibers. In addition, since thin fibers can be used as raw materials, carbon fiber fabrics with excellent conductivity can be produced. On the other hand, conventionally, for example in Patent Document 1, carbon fiber fabrics are produced by going through a flame-retardant process as fibers, which has the problem of higher energy and equipment costs compared to directly flame-retarding the fabric.

[0028] <Carbonization process> The carbon fiber fabric of the present invention can be produced by firing a flame-resistant fabric in an inert atmosphere. Such firing can be carried out using either a batch-type or a continuous-type heating furnace. The inert atmosphere can be obtained by flowing an inert gas such as nitrogen gas or argon gas through the furnace.

[0029] The maximum firing temperature is preferably in the range of 800 to 3,000°C, and more preferably in the range of 1,100 to 1,500°C. A maximum temperature of 800°C or higher is preferable because it promotes carbonization of the flame-resistant fabric, resulting in a carbon fiber fabric with excellent conductivity and thermal conductivity. On the other hand, a maximum temperature of 3,000°C or lower is preferable because it reduces the operating cost of the heating furnace.

[0030] <Gas diffusion layer> A carbon fiber fabric with a microporous layer formed by applying a microporous layer coating solution to one side is suitably used as a gas diffusion layer. The microporous layer coating solution may contain a dispersion medium such as water or an organic solvent, or a dispersion aid such as a surfactant. Water is preferred as the dispersion medium, and a nonionic surfactant is preferred as the dispersion aid. It is preferable if the microporous layer coating solution contains conductive fine particles, as this allows for the acquisition of a microporous layer with excellent conductivity. It is also preferable if the microporous layer coating solution contains a water-repellent resin, as this allows for the acquisition of a microporous layer with excellent drainage properties for discharging water generated by electrochemical reactions in the fuel cell to the separator, as well as excellent mechanical strength. The microporous layer coating solution can be applied to carbon fiber fabrics using various commercially available coating devices. Coating methods include screen printing, rotary screen printing, spray atomization, intaglio printing, gravure printing, die coater coating, bar coating, and blade coating, but die coater coating is preferred because it allows for the quantification of the coating amount regardless of the surface roughness of the carbon fiber fabric. The coating methods exemplified above are merely examples and are not necessarily limited to these.

[0031] <Membrane electrode assembly> In the present invention, a membrane electrode assembly can be formed by bonding the above-mentioned carbon fiber fabric to at least one side of an electrolyte membrane having catalyst layers on both sides. When using a carbon fiber fabric with a microporous layer formed on it to serve as a gas diffusion layer, it is preferable to arrange it so that the microporous layer side is in contact with the catalyst layer side, as this facilitates back diffusion of the generated water and increases the contact area between the catalyst layer and the gas diffusion electrode layer, thereby reducing electrical resistance. Platinum is usually used as the catalyst for the catalyst layer. It is preferable to use a perfluorosulfonic acid-based polymer material with high proton conductivity, oxidation resistance, and heat resistance for the electrolyte membrane.

[0032] <Fuel cell> A fuel cell is one aspect of the present invention. The fuel cell of the present invention is a fuel cell having the carbon fiber fabric of the present invention. That is, it refers to a fuel cell having separators at both ends of the membrane electrode assembly described above. The separator has a flow path to allow fuel gas to flow into the anode-side gas diffusion layer and oxidizing gas to flow into the cathode-side gas diffusion layer. The separator and the flow path can be of any shape that allows fuel gas and oxidizing gas to flow in and out. A fuel cell stack can be constructed by stacking multiple of the above fuel cells.

[0033] <Liquid electrolyzer> A liquid electrolytic apparatus is one aspect of the present invention. The liquid electrolytic apparatus of the present invention has the carbon fiber fabric of the present invention. That is, it has a liquid electrolytic cell having separators on both sides of the above-mentioned membrane electrode assembly.

[0034] <Redox flow battery> A redox flow battery is one aspect of the present invention. The redox flow battery of the present invention uses the carbon fiber fabric of the present invention as the positive electrode and / or negative electrode. The carbon fiber fabric of the present invention can be used as an electrode in either a flow-through type or a flow-by type cell.

[0035] <Surface heater> A planar heater is one aspect of the present invention. The planar heater in the present invention is a planar body in which electrodes are attached to both ends of the carbon fiber fabric of the present invention, and insulating and heat-dissipating sheets are laminated to both sides. Because it has low resistivity, a large amount of heat generated per unit area, and a large area of ​​heat conducted to the heat sink compared to nichrome wire, etc., it can be made into a heater with good rapid heating properties. Also, because the threads are thin, a large aperture ratio can be made, making it a transparent planar heater. By selecting the materials for the front and back surfaces, a planar heater with good rapid heating properties, light transmission, flexibility, high temperature resistance, and little temperature variation within the surface can be obtained.

[0036] <Mobile> A mobile body is one aspect of the present invention. The fuel cell in the present invention is a fuel cell installed in a mobile body such as an automobile, ship, or railway, and can be used as a power source for said mobile body. In other words, the mobile body of the present invention refers to a mobile body equipped with the fuel cell of the present invention. [Examples]

[0037] The present invention will be specifically described below with reference to examples. However, the present invention is not limited in any way by the following examples.

[0038] <Manufacturing of carbon fiber fabrics> Acrylic filament was produced by cutting acrylic tow, and then 130-meter-long acrylic spun yarn was produced through drawing, roving, and spinning processes. Next, an acrylic fabric woven using acrylic spun yarn was heat-treated in a furnace with a maximum temperature of 250°C to produce a flame-resistant fabric. This flame-resistant fabric was fired in a furnace maintained in a nitrogen gas atmosphere with a maximum temperature of 1,250°C to obtain a carbon fiber fabric.

[0039] <Measurement method> [Length of carbon fibers in carbon fiber fabric] The carbon fiber fabric was cut to extract the warp and weft threads, and the length of the carbon fibers obtained by separating the extracted threads was measured. For 10 carbon fibers obtained from the warp and weft threads, the average length was calculated as the length of carbon fibers contained in the warp and weft threads, respectively.

[0040] [Diameter of carbon fibers in carbon fiber fabric] Using a microscope or other magnification equipment, five arbitrary points on the warp and weft threads were measured under a 2,500x magnification, and the average values ​​of these measurements were calculated as the diameters of the warp and weft threads.

[0041] [Number of carbon fibers contained in spun yarn in carbon fiber fabric] Using a microscope or other magnification equipment, the cross-sections of the warp and weft threads were examined at five locations each under a 500x magnification. The average number of carbon fibers contained in each cross-section was calculated as the number of carbon fibers in the spun warp and weft threads, respectively. The cross-sections of the warp and weft threads were revealed by cutting the carbon fiber fabric with a sharp blade. In the case of plied yarn, the number of carbon fibers contained in the two single yarns constituting the plied yarn was examined, and the average value of these was taken as the number of carbon fibers in the spun yarn.

[0042] [Twist angle of carbon fiber fabric] Using a microscope or other magnification equipment, measurements were taken at five arbitrary points on both the warp and weft threads under 250x magnification. The average values ​​of the intersection angles of each carbon fiber relative to the center line of the yarn were calculated as the twist angle of the warp and weft threads. In the case of double yarn, the twist angle was defined as the intersection angle of the carbon fibers relative to the center line at the intersection of the upper and lower threads.

[0043] [Open area ratio of carbon fiber fabric] The warp pitch Tp, weft pitch Yp, warp width Tw, and weft width Yw were measured under 200x magnification using a microscope or other magnification equipment, and the aperture ratio was derived using the above formula (1). This measurement was performed at five arbitrary points, and the average value was taken as the opening ratio of the carbon fiber fabric.

[0044] [Tensile strength of carbon fiber fabrics] The tensile strength of carbon fiber fabric was measured using the "Load Measuring Instrument LTS-B Series" manufactured by MinebeaMitsumi Inc. A tensile test specimen 1 of carbon fiber fabric, cut to the size shown in Figure 3, was attached to the load measuring instrument. The specimen was pulled at a speed of 0.2 mm / min in the longitudinal direction until it broke, and the peak strength was measured. This measurement was performed five times with different tensile test specimens, and the average value was taken as the tensile strength.

[0045] [The springiness of carbon fiber fabrics] The spring properties of carbon fiber fabric were measured using the compression test mode of the "Autograph®" AGS-X manufactured by Shimadzu Corporation. A 20mm x 20mm piece of carbon fiber fabric was cut, sandwiched between smooth metal rigid electrodes, and an average pressure of 2.0 MPa was applied. After releasing the pressure, it was repressurized and an average pressure of 1.5 MPa was applied, and the thickness of the carbon fiber fabric was measured after 25 seconds. Then, the average pressure was reduced to 0.5 MPa, and the thickness of the carbon fiber fabric was measured again after 25 seconds. The difference between the thickness of the carbon fiber fabric at an average pressure of 0.5 MPa and the thickness at an average pressure of 1.5 MPa was defined as the spring property.

[0046] [Electrical resistance of carbon fiber fabrics] The electrical resistance of a carbon fiber fabric was measured using the compression test mode of the "Autograph®" AGS-X manufactured by Shimadzu Corporation. The carbon fiber fabric was cut to a size of 20 mm x 20 mm, sandwiched between rigid electrodes made of smooth, gold-plated metal, and subjected to an average pressure of 1.0 MPa. The electrical resistance per unit area was calculated by measuring the voltage between the upper and lower electrodes when a current of 1 A was passed through them under these conditions.

[0047] [Pressurized thickness of carbon fiber fabric] The compression thickness of carbon fiber fabric was measured using the compression test mode of the "Autograph®" AGS-X manufactured by Shimadzu Corporation. The carbon fiber fabric was cut to a size of 20 mm x 20 mm, sandwiched between smooth metal rigid electrodes, and the thickness of the carbon fiber fabric was measured when an average pressure of 1.0 MPa was applied.

[0048] (Example 1) A carbon fiber fabric was prepared according to the above-described method for "Preparation of Carbon Fiber Fabric." A plain weave acrylic fabric was prepared using 130-meter count long-staple acrylic spun yarn as both the warp and weft threads. The density of the fabric can be expressed by the fabric cover factor Kc, which is the sum of the warp and weft cover factors (Kt + Ky) consisting of the yarn thickness and the number of threads per inch. Kt = Warp Cover Factor = nt × √9000 / Nt Ky = Weft Cover Factor = ny × √9000 / Ny nt = warp density per inch, ny = weft density per inch Nt = Warp yarn count in meters, Ny = Weft yarn count in meters For carbon fiber fabrics obtained by flame-retarding and carbonizing plain weave acrylic fabric with a warp thread count of 54 threads / inch and a weft thread count of 50 threads / inch, and a Kc=865, the length and diameter of carbon fibers in the warp and weft threads, the number of carbon fibers in the spun yarn of each thread, the open area ratio, the twist angle of the warp threads, the basis weight, the tensile strength, the springiness, the electrical resistance, and the compressed thickness were measured according to the <measurement method> described above. The results are shown in Table 1.

[0049] [Table 1]

[0050] (Example 2) In Example 2, carbon fiber fabrics were fabricated and various measurements were performed in the same manner as in Example 1, except that a 200-meter count short-spun acrylic spun yarn without long fibers was used as the weft, the warp thread count was 52 threads / inch and the weft thread count was 70 threads / inch, and a plain weave acrylic fabric with Kc = 1097 was produced. The results are shown in Table 1.

[0051] (Example 3) In Example 3, a carbon fiber fabric was prepared and various measurements were performed in the same manner as in Example 1, except that a plain weave acrylic fabric with Kc=941 was made using 130-meter count long-staple acrylic spun yarn (ply-ply) for both the warp and weft, with a warp thread count of 50 threads / inch and a weft thread count of 30 threads / inch. The results are shown in Table 1. Figure 2 shows a micrograph (250x magnification) of the carbon fiber fabric according to Example 3 of the present invention.

[0052] (Example 4) In Example 4, carbon fiber fabrics were prepared and various measurements were performed in the same manner as in Example 3, except that a 3 / 1 twill weave was selected for the weaving method. The results are shown in Table 1.

[0053] (Example 5) In Example 5, the carbon fiber fabric was prepared and various measurements were performed in the same manner as in Example 4, except that the number of weft threads was set to 45 threads / inch and a 3 / 1 twill acrylic fabric with Kc=1118 was produced. The results are shown in Table 1.

[0054] (Example 6) In Example 6, the carbon fiber fabric was prepared and various measurements were performed in the same manner as in Example 4, except that the number of weft threads was set to 60 threads / inch and a 3 / 1 twill acrylic fabric with Kc = 1294 was produced. The results are shown in Table 1.

[0055] (Comparative Example 1) In Comparative Example 1, a 200-meter count short-spun acrylic spun yarn (ply yarn) was used for the warp, and a 200-meter count short-spun acrylic spun yarn (single yarn) was used for the weft. In Comparative Example 1, the warp thread count was 70 threads / inch and the weft thread count was 36 threads / inch. A plain weave acrylic fabric with Kc=906 was flame-retarded and carbonized to obtain a carbon fiber fabric. The carbon fiber fabric was then prepared and various measurements were performed in the same manner as in Example 1, according to the <Measurement Method> described above. The results are shown in Table 1.

[0056] (Comparative Example 2) In Comparative Example 2, carbon fiber fabrics were prepared and various measurements were performed in the same manner as in Comparative Example 1, except that a 200-meter count short-spun acrylic spun yarn, which did not contain long fibers in the warp and weft, was used, the weft thread count was set to 44 threads / inch, and a 3 / 2 twill weave acrylic fabric with Kc = 864 was produced. The results are shown in Table 1.

[0057] (Comparative Example 3) In Comparative Example 3, carbon fiber fabric was prepared and various measurements were performed in the same manner as in Example 1, except that acrylic fabric was made using single yarns of 130-meter count short-spun acrylic yarn that did not contain long fibers for both the warp and weft. The results are shown in Table 1.

[0058] As shown in Table 1, Comparative Examples 1-3, in which fabrics were made using spun yarns that do not contain long fibers for both the warp and weft, exhibit lower tensile strength and springiness than Examples 1-6. Thus, as in Examples 1-6, it can be said that carbon fiber fabrics with excellent conductivity, tensile strength, and springiness can be obtained by using spun yarns in which at least one of the warp and weft threads contains long fibers.

[0059] The carbon fiber fabric of the present invention can be suitably used as electrodes for fuel cells, liquid electrolytic devices, and redox flow batteries, and in particular as gas diffusion electrodes for polymer electrolyte fuel cells used as power sources for mobile vehicles such as fuel cell vehicles and ships. It can also be suitably used as general-purpose heating equipment and industrial heaters, as well as as general-purpose and industrial flat heaters that require flexible shape changes and are installed to conform to the shape of seats and backs of automobile seats and chairs, floors, walls, etc. [Explanation of Symbols]

[0060] 1. Tensile test specimen

Claims

1. A carbon fiber fabric formed by interweaving warp and weft threads, The warp and / or weft threads are made of spun yarn consisting of carbon fibers with a length of 90 mm or more and 230 mm or less. Carbon fiber fabric.

2. The warp and / or weft threads are made of spun yarn consisting of carbon fibers with a length of 90 mm or more and 120 mm or less. The carbon fiber fabric according to claim 1.

3. The twist angle of the aforementioned spun yarn is 5° or more and 35° or less. The carbon fiber fabric according to claim 1.

4. The warp and / or weft threads are double-ply yarns. The carbon fiber fabric according to claim 1.

5. The weave structure is either plain weave or twill weave. The carbon fiber fabric according to claim 1.

6. The thickness when pressurized at 1 MPa is between 50 μm and 150 μm. The carbon fiber fabric according to claim 1.

7. The diameter of the carbon fiber is 3 μm or more and 10 μm or less. The carbon fiber fabric according to claim 1.

8. The number of carbon fibers contained in the cross-section of the aforementioned spun yarn is 50 to 250 per single yarn. The carbon fiber fabric according to claim 1.

9. The opening ratio is between 5% and 75%. The carbon fiber fabric according to claim 1.

10. A fuel cell having a carbon fiber fabric according to any one of claims 1 to 9.

11. A liquid electrolytic apparatus having a carbon fiber fabric according to any one of claims 1 to 9.

12. A redox flow battery having a carbon fiber fabric according to any one of claims 1 to 9.

13. A planar heater having a carbon fiber fabric according to any one of claims 1 to 9.

14. A mobile body equipped with the fuel cell described in claim 10.

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