Carbon fiber-resin composite sheet

Abstract

To provide a novel carbon fiber-resin composite sheet having a portion with good gas impermeability and / or good mechanical strength and a portion with good electrical conductivity.SOLUTION: As shown in FIG. 1, a carbon fiber-resin composite sheet 10 according to the present invention is composed of a sheet containing carbon fiber and resin, includes a first portion 12 and a second portion 14 that are continuous and distinct in the planar direction, the density of the first portion 12 is greater than the density of the second portion 14, and the number of the first portions 12 and the second portions 14 is 10 or less each.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a carbon fiber-resin composite sheet, particularly a carbon fiber-resin composite sheet used in a fuel cell separator.

Background Art

[0002] Conventionally, as fuel cell separators, those made of metal materials and those made of carbon materials have been developed. A fuel cell separator made of a carbon material is useful in terms of light weight and chemical resistance compared to those mainly using metal materials. On the other hand, such a fuel cell separator may not obtain sufficient strength, and in particular, the probability of gas leakage due to crack generation is higher than that of metal, and also, when the amount of a binder component such as resin is increased to prevent this crack, the conductivity decreases. In order to solve such problems, various proposals have been made.

[0003] Patent Document 1 discloses a fuel cell separator characterized by having a conductive gas barrier layer (B) on a conductive layer (A) in which conductive fibers are bound and solidified with a synthetic resin.

[0004] Patent Document 2 discloses a fuel cell separator including a base material, wherein the base material includes a first conductive carbon material and a first conductive layer formed in a resin material, and a second conductive carbon material, and a second conductive layer formed adjacent to the first conductive layer on at least one side in the thickness direction of the first conductive layer and bonded to the first conductive layer through the resin material.

[0005] Patent Document 3 discloses an electrically conductive article used as an electrode in a fuel cell, which is composed of a reinforcing fiber having electrical conductivity contained in a base material having the thickness and mechanically oriented so as to be parallel to the thickness.

[0006] In Patent Document 4, a method for manufacturing a fuel cell separator is disclosed, which includes a step of manufacturing a stampable sheet containing a conductive filler and a polymer material, a step of supplying the stampable sheet to a molding machine equipped with a pair of molds engraved with the shape of a fuel cell separator, and a step of thermally molding the stampable sheet supplied to the molding machine into the shape of a separator.

[0007] In Patent Document 5, a method for manufacturing a fuel cell separator is disclosed, which includes providing a fiber sheet and a raw material sheet having carbon particles and a resin applied to the fiber sheet, and pressing the raw material sheet so as to have uneven shapes forming gas flow channels to obtain the top portions and the transition portions. In the pressing of the raw material sheet, the raw material sheet is pressed such that the pressing rate of the top portions is higher than the pressing rate of the transition portions.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0009] The present invention provides a novel carbon fiber-resin composite sheet having a portion with good gas impermeability and / or good mechanical strength and a portion with good electrical conductivity.

Means for Solving the Problems

[0010] As a result of intensive studies, the inventors of the present invention have found that the above problems can be solved by the following means, and have completed the present invention. That is, the present invention is as follows: <Aspect 1> A carbon fiber-resin composite sheet composed of a sheet containing carbon fibers and a resin, which is continuous and has a first portion and a second portion that are distinguishable in the plane direction, wherein the density of the first portion is greater than the density of the second portion, and the number of the first portion and the second portion is each 10 or less. Carbon fiber-resin composite sheet. <Aspect 2> The carbon fiber-resin composite sheet according to Aspect 1, satisfying at least one of the following (i), (ii), and (iii): (i) The conductivity in the thickness direction of the first portion is smaller than the conductivity in the thickness direction of the second portion; (ii) The gas permeability in the thickness direction of the first portion is smaller than the gas permeability in the thickness direction of the second portion; and (iii) The flexural modulus of the first portion is greater than the flexural modulus of the second portion. <Aspect 3> The carbon fiber-resin composite sheet according to Aspect 1, wherein the number of the first portion and the second portion is one each. <Aspect 4> The carbon fiber-resin composite sheet according to any one of Aspects 1 to 3, wherein the first portion exists so as to surround the second portion. <Aspect 5> The carbon fiber-resin composite sheet according to any one of Aspects 1 to 4, wherein the gas permeability in the thickness direction of the second portion is 6.00×10 -5 cm 3 sec -1 cm -2 or less, and the volume resistivity in the thickness direction of the second portion is 50 mΩ·cm 2 or less. Carbon fiber-resin composite sheet according to any one of Aspects 1 to 4. <Aspect 6> A fuel cell separator composed of the carbon fiber-resin composite sheet according to any one of Aspects 1 to 5. <Aspect 7> A fuel cell having the separator for a fuel cell described in Aspect 6.

Advantages of the Invention

[0011] According to the present invention, it is possible to provide a novel carbon fiber-resin composite sheet having a portion with good gas impermeability and / or good mechanical strength and a portion with good electrical conductivity.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0013] 《Carbon Fiber-Resin Composite Sheet》 As shown in FIG. 1, the carbon fiber-resin composite sheet 10 of the present invention is composed of a sheet containing carbon fibers and a resin, has a continuous first portion 12 and a second portion 14 which are distinguishable in the plane direction, the density of the first portion 12 is greater than the density of the second portion 14, and the number of the first portion 12 and the second portion 14 is each 10 or less.

[0014] The first part with a high density can have good gas impermeability and / or good mechanical strength, such as breaking strength, due to its dense structure. On the other hand, the inventors have found that the second part with a low density can unexpectedly obtain good electrical conductivity. Without wishing to be bound by theory, this is because when the structure is dense, the resin is likely to be exposed on the surface of the carbon fiber-resin composite sheet, thereby increasing the resistance, while when the density is appropriate, the carbon fibers are likely to be exposed on the surface of the carbon fiber-resin composite sheet, so it is considered that the resistance is reduced.

[0015] The carbon fiber-resin composite sheet of the present invention can be used in various applications, for example, it can be a separator for a fuel cell.

[0016] In particular, when the carbon fiber-resin composite sheet is a separator for a fuel cell, as shown in FIGS. 1(a) and (b), it is preferable that there is one each of the first part 12 and the second part 14 from the viewpoint of dividing the power supply part and the seal part. In this case, it is particularly preferable that the first part 12 exists so as to surround the second part 14.

[0017] The carbon fiber-resin composite sheet of the present invention can satisfy at least one of the following (i), (ii), and (iii): (i) The electrical conductivity in the thickness direction of the first part is smaller than the electrical conductivity in the thickness direction of the second part; (ii) The gas permeability in the thickness direction of the first part is smaller than the gas permeability in the thickness direction of the second part; and (iii) The flexural modulus of the first part is larger than the flexural modulus of the second part.

[0018] Hereinafter, the first part and the second part of the carbon fiber-resin composite sheet of the present invention will be described.

[0019] 〈First part〉 The first part is the part whose density is larger than the density of the second part.

[0020] The number of the first parts may be 10 or less, 8 or less, 5 or less, 3 or less, or 1.

[0021] The density of the first part is not particularly limited as long as it is greater than the density of the second part. For example, it may be 1.20 g / cm 3 or more, 1.22 g / cm 3 or more, or 1.25 g / cm 3 or more, and may also be 1.50 g / cm 3 or less, 1.40 g / cm 3 or less, 1.35 g / cm 3 or less, or 1.30 g / cm 3 or less.

[0022] In particular, from the viewpoint of conductivity, it is preferable that the ratio of the density of the first part to the true density of the material is 0.96 or more, or 0.97 or more, and 0.99 or less, or 0.98 or less.

[0023] Here, in the present invention, the "true density of the material" means the weighted average of the true densities of the carbon fiber and the resin constituting the carbon fiber-resin composite sheet, weighted by the mass content.

[0024] When the carbon fiber-resin composite sheet of the present invention is a separator for a fuel cell, the first part can be a seal part of the separator, particularly a peripheral seal part. On the other hand, the first part does not have to form a flow path for hydrogen and / or oxygen in the fuel cell.

[0025] The gas permeability of the first part can be 1.00×10 -6 cm 3 sec -1 cm -2 or less. This gas permeability can be 7.00×10 -7 cm 3 sec -1 cm -2 or less, 5.00×10 -7 cm 3 sec -1 cm -2Hereinafter, 3.00×10 -7 cm 3 sec -1 cm -2 Hereinafter, 1.00×10 -7 cm 3 sec -1 cm -2 Hereinafter, 7.00×10 -8 cm 3 sec -1 cm -2 Hereinafter, 5.00×10 -8 cm 3 sec -1 cm -2 Hereinafter, 3.00×10 -8 cm 3 sec -1 cm -2 Hereinafter, 1.00×10 -8 cm 3 sec -1 cm -2 Hereinafter, 7.00×10 -9 cm 3 sec -1 cm -2 Hereinafter, or 6.00×10 -9 cm 3 sec -1 cm -2 Hereinafter, or 5.50×10 -9 cm 3 sec -1 cm -2 It may be hereinafter, and also 1.00×10 -10 cm 3 sec -1 cm -2 It may be above. For example, this gas permeability may be 1.00×10 -10 cm 3 sec -1 cm -2 Above 1.00×10 -6 cm 3 sec -1 cm -2 It may be below.

[0026] Here, in this specification, the gas permeability is measured by the differential pressure method in accordance with JIS K7126-1:2006 for the gas permeability of the produced conductive sheet.

[0027] The ratio of the gas permeability in the thickness direction of the first part to the gas permeability in the thickness direction of the second part may be 1.00×10 -2 or less. This ratio may be 9.00×10 -3 or less, 7.00×10 -3 or less, 5.00×10 -3 or less, 3.00×10 -3 or less, 1.00×10 -3 or less, 9.00×10 -4 or less, 5.00×10 -4 or less, 3.00×10 -4 or less, or 2.50×10 -4 or less, and may also be 1.00×10 -5 or more, 3.00×10 -5 or more, 5.00×10 -5 or more, 7.00×10 -5 or more, or 9.00×10 -5 or more. For example, this ratio may be 1.00×10 -5 or more and 1.00×10 -2 or less.

[0028] The volume resistivity in the thickness direction of the first part can be 100 mΩ·cm 2 or less. This volume resistivity can be 90 mΩ·cm 2 or less, 80 mΩ·cm 2 or less, 70 mΩ·cm 2 or less, or 60 mΩ·cm 2 or less, and can also be 20 mΩ·cm 2 or more, 25 mΩ·cm 2 or more, 30 mΩ·cm 2 or more, 35 mΩ·cm 2 or more, 40 mΩ·cm 2 or more, 45 mΩ·cm 2 or more, or 55 mΩ·cm 2 or more. For example, this volume resistivity can be 20 mΩ·cm 2 or more and 100 mΩ·cm 2 or less.

[0029] Here, in this specification, the volume resistivity is measured by placing carbon papers on both sides of the fabricated carbon fiber-resin composite sheet, sandwiching this between flat electrodes plated with gold, applying a pressure of 1 MPa, then applying a current of 1 A to these flat electrodes and measuring the voltage between the electrodes, and subtracting the resistance at the interface between the flat electrodes and the carbon papers from the obtained resistance.

[0030] The ratio of the volume resistivity in the thickness direction of the first part to the volume resistivity in the thickness direction of the second part can be 3.0 or more. This ratio can be 3.3 or more, 3.5 or more, or 3.7 or more, and can also be 6.0 or less, 5.5 or less, 5.2 or less, 5.0 or less, or 4.7 or less. For example, this ratio can be 3.0 or more and 6.0 or less.

[0031] 〈Second part〉 The second part is a part whose density is smaller than the density of the first part.

[0032] The density of the second part is not particularly limited as long as it is smaller than the density of the first part. For example, it can be 0.90 g / cm 3 or more, 0.95 g / cm 3 or more, 1.00 g / cm 3 or more, 1.05 g / cm 3 or more, or 1.08 g / cm 3 or more, and can also be 1.25 g / cm 3 or less, or 1.22 g / cm 3 or less.

[0033] In particular, from the perspective of conductivity, the ratio of the density of the second part to the true density of the material is preferably 0.82 or more, or 0.83 or more, and 0.95 or less, 0.94 or less, or 0.93 or less.

[0034] The number of the second parts can be 10 or less, 8 or less, 5 or less, 3 or less, or 1.

[0035] The gas permeability in the thickness direction of the second part is 6.00×10-5 cm 3 sec -1 cm -2 It can be as follows. This gas permeability is 5.50×10 -5 cm 3 sec -1 cm -2 Hereinafter, 5.20×10 -5 cm 3 sec -1 cm -2 Hereinafter, 5.00×10 -5 cm 3 sec -1 cm -2 Hereinafter, or 4.80×10 -5 cm 3 sec -1 cm -2 It can be as follows, and also 1.00×10 -9 cm 3 sec -1 cm -2 Above, 3.00×10 -9 cm 3 sec -1 cm -2 Above, 5.00×10 -9 cm 3 sec -1 cm -2 Above, 7.00×10 -9 cm 3 sec -1 cm -2 Above, 1.00×10 -8 cm 3 sec -1 cm -2 Above, 3.00×10 -8 cm 3 sec -1 cm -2 Above, 5.00×10 -8 cm 3 sec -1 cm -2 Above, 7.00×10 -8 cm 3 sec -1 cm -2 Above, 1.00×10 -7 cm 3 sec -1 cm -2 Above, 3.00×10-7 cm 3 sec -1 cm -2 Above, 5.00×10 -7 cm 3 sec -1 cm -2 Above, 7.00×10 -7 cm 3 sec -1 cm -2 Above, or 1.00×10 -6 cm 3 sec -1 cm -2 Above may be satisfied. This gas permeability is, for example, 1.00×10 -9 cm 3 sec -1 cm -2 Above 6.00×10 -5 cm 3 sec -1 cm -2 Below may be satisfied.

[0036] The volume resistivity in the thickness direction of the second part can be 50 mΩ·cm 2 Below. This volume resistivity can be 45 mΩ·cm 2 Below, 40 mΩ·cm 2 Below, 35 mΩ·cm 2 Below, 30 mΩ·cm 2 Below, 25 mΩ·cm 2 Below, 20 mΩ·cm 2 Below, 18 mΩ·cm 2 Below, or 15 mΩ·cm 2 Below and can also be 1 mΩ·cm 2 Above, 3 mΩ·cm 2 Above, 5 mΩ·cm 2 Above, 7 mΩ·cm 2 Above, or 10 mΩ·cm 2 Above. This volume resistivity can be, for example, 1 mΩ·cm 2 Above 50 mΩ·cm 2 Below may be satisfied.

[0037] Hereinafter, each material constituting the sheet of the present invention will be described.

[0038] <Carbon fiber> As the carbon fiber, for example, mild fiber, chopped fiber, etc. can be used. These may be used alone or in combination.

[0039] The average length of the carbon fiber can be, for example, 100 μm or more, 300 μm or more, 500 μm or more, 1.0 mm or more, 1.5 mm or more, 2.0 mm or more, 2.5 mm or more, or 2.8 mm or more, and can also be 10.0 mm or less, 8.0 mm or less, 5.0 mm or less, 4.0 mm or less, or 3.5 mm or less.

[0040] The average fiber diameter of the carbon fiber can be 1 μm or more, 3 μm or more, or 5 μm or more, and can also be 50 μm or less, 40 μm or less, 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less.

[0041] The content of the carbon fiber may be 10% by mass or more, 15% by mass or more, 20% by mass or more, or 23% by mass or more with respect to the mass of the carbon fiber - resin composite sheet, and may also be 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, 30% by mass or less, or 27% by mass or less.

[0042] <Resin> The resin may be a resin in any form, for example, a resin fiber aggregate.

[0043] As the resin, it is preferable to use a resin that can withstand the chemical environment of the fuel cell, does not soften or melt at the reaction temperature of the fuel cell, and softens or melts during press molding. Examples of such resins include polypropylene, polyethylene, polyamide, polyphenylene sulfide (PPS), polyvinylidene fluoride (PVDF), polyetherimide (PEI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), liquid crystal polymer (LCP), polyimide (PI), polycarbonate (PC), polyphenylene ether (PPE), polysulfone (PSU), polyethersulfone (PES), polyetheretherketone (PEEK), polyurethane, epoxy resin, silicone resin, urea resin, phenol resin, thermosetting polyimide, thermosetting isocyanate, and polymers or mixtures of two or more of the above.

[0044] (Resin: Resin fiber aggregate) The resin fiber aggregate can be obtained by melting the resin fibers, particularly by partially melting them by hot pressing. The resin constituting the resin fibers may be the above-mentioned resin.

[0045] 《Separator for Fuel Cell》 The separator for a fuel cell of the present invention is composed of the above carbon fiber-resin composite sheet.

[0046] In particular, in the separator for a fuel cell of the present invention, when the above carbon fiber-resin composite sheet has one each of the first and second parts, the first part can be a seal part, and the second part can be a power generation part. In this case, good conductivity can be obtained in the power generation part, and gas permeation can be more effectively suppressed in the seal part.

[0047] 《Fuel Cell》 The fuel cell of the present invention has the above separator for a fuel cell.

[0048] The fuel cell may have a general configuration as long as it has the above-described separator for a fuel cell. For example, it may have a separator for a fuel cell, a cathode gas diffusion layer, a cathode catalyst electrode layer, an electrolyte layer, an anode catalyst electrode layer, and a separator for a fuel cell in this order.

[0049] Known ones used in the configuration of a cathode gas diffusion layer, a cathode catalyst electrode layer, an electrolyte layer, an anode catalyst electrode layer, and a fuel cell can be used.

[0050] 《Method for Manufacturing Carbon Fiber-Resin Composite Sheet》 The carbon fiber-resin composite sheet of the present invention can be obtained by a method including the following: obtaining a precursor structure having a thermoplastic resin and carbon fibers, pressing the precursor structure, while applying pressure by pressing, heating the precursor structure to soften or melt the thermoplastic resin and holding it in this state, then cooling to solidify the thermoplastic resin, and then releasing the pressure to obtain a carbon fiber-resin composite sheet.

[0051] Here, in order for the carbon fiber-resin composite sheet to be continuous and have a first part and a second part distinguishable in the plane direction, any operation can be performed. For example, as shown in FIG. 2(a), a precursor structure 10' with a uniform thickness is formed in advance, and the pressing pressure during pressing is made higher in the first part than in the second part, or, as shown in FIG. 2(b), for example, in a part 12' corresponding to the first part of the precursor structure 10', by arranging a spacer 30 on the press 20, the final thickness during pressing is made thinner in the first part than in the second part, and pressing is performed to obtain a carbon fiber-resin composite sheet 10 having a first part 12 and a second part 14 as shown in FIG. 2(c).

[0052] Further, for example, as shown in Fig. 3(a), the precursor structure 10' is pre-formed such that the thickness of the portion 12' corresponding to the first part of the precursor structure is thicker than the thickness of the portion 14' corresponding to the second part of the precursor structure, as shown in Fig. 3(b). Then, as shown in Fig. 3(c), pressing is performed using a press machine 20 such that the thickness of the resulting carbon fiber-resin composite sheet becomes uniform, and a carbon fiber-resin composite sheet 10 having a first part 12 and a second part 14 can be obtained, as shown in Fig. 3(d).

[0053] 〈Fabrication of precursor structure〉 The precursor structure has a thermoplastic resin and carbon fibers. In particular, when using thermoplastic resin fibers as the thermoplastic resin, the precursor structure may be a precursor fiber structure.

[0054] In particular, the precursor fiber structure can be obtained by a method including the following: Dispersing thermoplastic resin fibers and carbon fibers in water to obtain a precursor fiber aqueous dispersion, and Casting the obtained precursor fiber aqueous dispersion into a sheet shape, and dehydrating and drying it.

[0055] 〈Pressing of precursor structure〉 As described above, when the final thickness of the press during pressing is made thinner in the first part than in the second part, for example, the difference in the final thickness during pressing between the part that becomes the first part of the carbon fiber-resin composite sheet and the part that becomes the second part of the carbon fiber-resin composite sheet may be, for example, 0.35 mm or more, or 0.38 mm or more, and may also be 0.50 mm or less, 0.48 mm or less, or 0.46 mm or less. For example, the thickness of the spacer may be 0.35 mm or more and 0.50 mm or less.

[0056] The pressing pressure may be 6 MPa or more, 7 MPa or more, 8 MPa or more, or 9 MPa or more, and may also be 15 MPa or less, 14 MPa or less, 13 MPa or less, 12 MPa or less, or 11 MPa or less. For example, the pressing pressure may be 6 MPa or more and 15 MPa or less.

[0057] 〈Heating and Cooling of the Precursor Structure〉 The heating and cooling of the precursor structure is performed by heating the precursor fiber structure in a state where pressure is applied by pressing to soften or melt the thermoplastic resin and holding it in this state, then cooling to solidify the thermoplastic resin, and then releasing the pressure.

[0058] The heating temperature is not particularly limited as long as it is higher than the softening temperature or melting point of the thermoplastic resin and lower than the thermal decomposition temperature of the thermoplastic resin. For example, it may be 150°C or more, 170°C or more, 200°C or more, 220°C or more, or 240°C or more, and may also be 300°C or less, 290°C or less, 280°C or less, 270°C or less, or 260°C or less. For example, the heating temperature may be 150°C or more and 300°C or less.

[0059] The cooling temperature is not particularly limited as long as it can solidify the thermoplastic resin. For example, it may be 100°C or less, 90°C or less, 80°C or less, 750°C or less, 70°C or less, or 60°C or less, and may also be 15°C or more, 20°C or more, or 25°C or more. For example, the cooling temperature may be 15°C or more and 100°C or less.

Examples

[0060] The present invention will be specifically described by way of examples and comparative examples, but the present invention is not limited thereto.

[0061] 《Production of Carbon Fiber - Resin Composite Sheet》 〈Example 1〉 75 parts by mass of 6-nylon (registered trademark) as a thermoplastic resin fiber and 25 parts by mass of carbon fiber (average length 3 mm, average fiber diameter 7 μm) as a conductive fiber were dispersed in water to obtain a precursor fiber aqueous dispersion. This was cast onto a wire mesh, dehydrated, and then dried to produce a precursor fiber structure.

[0062] Next, the obtained precursor fiber structure was set in a mold at 70°C or lower, and a spacer was placed in the portion that becomes the first part so that the difference in the final thickness during pressing between the portion that becomes the first part of the carbon fiber-resin composite sheet and the portion that becomes the second part of the carbon fiber-resin composite sheet is 0.400 mm.

[0063] Next, this was pressed at a pressure of 10 MPa, heated to 250°C while maintaining the pressure, and held at this temperature for 1 minute.

[0064] Next, it was cooled to 70°C or lower while maintaining the pressure to produce the carbon fiber-resin composite sheet of Example 1.

[0065] The first part and the second part of the produced carbon fiber-resin composite sheet were each punched out, and the density was calculated from the volume and mass of the punched-out part. The true density of the material used was 1.30.

[0066] 〈Examples 2 - 3〉 Carbon fiber-resin composite sheets of Examples 2 - 3 were produced in the same manner as in Example 1, except that the difference in the final thickness during pressing between the portion that becomes the first part and the portion that becomes the second part was changed as shown in Table 1.

[0067] 〈Comparative Example 1〉 A separator of Comparative Example 1 was produced in the same manner as in Example 1, except that a graphite sheet as a conductive gas barrier sheet was sandwiched between the precursor fiber structures of Example 1 and pressed at a pressure of 10 MPa so that there is no difference in the final thickness during pressing between the portion that becomes the first part and the portion that becomes the second part.

[0068] <Comparative Example 2> A carbon fiber-resin composite sheet of Comparative Example 2 was produced in the same manner as in Example 1, except that no spacer was provided and pressing was performed so that there was no difference in the final thickness at the time of pressing between the portion that becomes the first part and the portion that becomes the second part.

[0069] <<Evaluation>> <<Gas Permeability>> The gas permeability of the second part of the produced conductive sheet was measured by the differential pressure method in accordance with JIS K7126-1:2006. Helium was used as the test gas, and the pressure of the test gas on the high-pressure side was set to 100 kPa.

[0070] <<Resistance>> Carbon papers were respectively placed on both sides of the produced carbon fiber-resin composite sheet, and this was sandwiched between flat electrodes plated with gold, and a pressure of 1 MPa was applied. Next, a current of 1 A was applied to these flat electrodes, and the resistance obtained by measuring the voltage between the electrodes was subtracted from the resistance at the interface between the flat electrodes and the carbon paper to measure the resistance at the interface between the produced carbon fiber-resin composite sheet and the carbon paper.

[0071] The configurations and evaluation results of the examples and comparative examples are shown in Table 1.

[0072]

Table 1

[0073] In the carbon fiber-resin composite sheets of Examples 1 to 3 in which the density of the first part is greater than the density of the second part, the gas permeability of the first part is 5.09×10 -9 cm 3 sec -1 cm -2 It is considered that the resistance value of this first part is 57.475 mΩ·cm 2 It can be understood that the carbon fiber-resin composite sheets of Examples 1 to 3 can have a portion with good gas impermeability and a portion with good conductivity.

[0074] On the other hand, it can be understood that the carbon fiber-resin composite sheet of Comparative Example 2 in which the density of the first part and the density of the second part are the same does not obtain a sufficient resistance value. As in Comparative Example 1, it can be understood that even when the conductive gas barrier sheet is interposed between two carbon fiber-resin composite sheets, a sufficient resistance value is still not obtained.

Explanation of Signs

[0075] 10 Carbon fiber-resin composite sheet 12 First part 14 Second part 10’ Precursor structure 12’ Part corresponding to the first part of the precursor structure 14’ Part corresponding to the second part of the precursor structure 20 Press 30 Spacer

Claims

1. A sheet containing carbon fibers and a resin, continuous and having a first part and a second part distinguishable in the plane direction, wherein the density of the first part is greater than the density of the second part, and the number of the first part and the second part is each 10 or less, a carbon fiber-resin composite sheet.

2. The carbon fiber-resin composite sheet according to Claim 1, satisfying at least one of the following (i), (ii), and (iii): (i) The conductivity in the thickness direction of the first part is smaller than the conductivity in the thickness direction of the second part; (ii) The gas permeability in the thickness direction of the first part is smaller than the gas permeability in the thickness direction of the second part; and (iii) The flexural modulus of the first part is greater than the flexural modulus of the second part.

3. The carbon fiber-resin composite sheet according to Claim 1, wherein the first part and the second part are each one.

4. The carbon fiber-resin composite sheet according to Claim 1 or 2, wherein the first part exists so as to surround the second part.

5. The gas permeability in the thickness direction of the second part is 6.00×10 －５ cm ３ sec －１ cm －２ or less, and The volume resistivity in the thickness direction of the second portion is 50 mΩ·cm ２ or less The carbon fiber-resin composite sheet according to Claim 1 or 2.

6. A fuel cell separator composed of the carbon fiber-resin composite sheet according to Claim 1 or 2.

7. A fuel cell having the fuel cell separator according to Claim 6.

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