JP2005209641A - Separator for fuel cell and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separator for a fuel cell, and its manufacturing method, excellent in contact resistance and feedthrough resistance. <P>SOLUTION: The separator for the fuel cell contains at least two layers of a low elastic modulus layer (A) with a single-sided or double-sided surface layer having a quality of a bending elastic modulus of 1.0×10<SP>1</SP>to 6.0×10<SP>3</SP>MPa and a bending strain of 1% or more, and a high elastic modulus layer (B) having a quality of a bending elastic modulus of more than 6.0×10<SP>3</SP>MPa. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a separator having good characteristics (for example, excellent contact resistance and penetration resistance) and a method for producing the same.

  In recent years, fuel cells have attracted attention from the viewpoint of environmental problems and energy problems. A fuel cell is a clean power generation device that uses hydrogen and oxygen to generate power by the reverse reaction of electrolysis and has no emissions other than water. Fuel cells are classified into several types depending on the type of electrolyte. Among these, polymer electrolyte fuel cells are most promising for automobiles and consumer use because they operate at low temperatures. Such a fuel cell can achieve high output power generation by stacking, for example, single cells composed of a polymer solid electrolyte, a gas diffusion electrode, a catalyst, and a separator.

  In the fuel cell having the above configuration, a separator for partitioning a single cell is usually supplied with a fuel gas (hydrogen, etc.) and an oxidant gas (oxygen, etc.), and a flow for discharging the generated moisture (water vapor). A path (groove) is formed. Therefore, the separator is required to have high gas impermeability capable of completely separating these gases and high conductivity in order to reduce internal resistance. Furthermore, it is required to have excellent thermal conductivity, durability, strength and the like.

  In order to achieve these requirements, conventionally, such a fuel cell separator has been studied from both a metal material and a carbon material. Attempts have been made to coat noble metals and carbon on the surface of metal materials due to the problem of corrosion resistance, but sufficient durability cannot be obtained, and the cost of coating becomes a problem.

  Many studies have also been made on carbon materials for fuel cell separators, including molded products obtained by press-molding expanded graphite sheets, molded products obtained by impregnating and curing carbon sintered bodies, and thermosetting resins. Examples of the fuel cell separator material include glassy carbon obtained by firing, a molded product obtained by mixing carbon powder and resin, and the like.

  For example, Patent Document 1 discloses isotropic graphite obtained by adding a binder to carbonaceous powder, heating and mixing, then performing CIP molding (Cold Isostatic Pressing), then firing and graphitizing. A complicated process is disclosed in which a material is impregnated with a thermosetting resin, cured, and a groove is carved by cutting.

  Patent Document 2 discloses that paper containing carbon powder or carbon fiber is impregnated with a thermosetting resin, then laminated and pressure-bonded, and fired. Patent Document 3 discloses that a phenol resin is injection-molded into a separator-shaped mold and fired.

  Although the fired material as shown in these examples shows high conductivity and heat resistance, there is a problem that the time required for firing is long, the productivity is poor, and the bending strength is poor. Furthermore, when cutting is required, mass productivity is further poor and the cost is high, so that there are many difficult aspects as a material to be spread in the future.

  On the other hand, reduction of contact resistance, which is a dominant factor in the conductivity of the fuel cell separator, is important. Several attempts have been made to devise the separator structure and reduce the contact resistance. For example, Patent Document 4 discloses that the surface of a separator is coated with highly conductive metal or carbon. Patent Document 5 discloses that a surface of a molded body of a conductive resin composition is coated with a conductive polymer. Patent Document 6 discloses that a conductive material is coated on the surface or buried in the vertical direction inside.

In addition, Patent Document 7 discloses that the resin-rich layer (resin-rich layer) on the surface of the separator is ground to improve the area ratio of the carbon powder on the surface. Patent Document 8 discloses that the adhesion of the contact surface is improved by using rubber as a binder.
JP-A-8-222241. JP-A-60-161144. JP 2001-68128 A. JP 2001-196076 A. Japanese Patent Laid-Open No. 2002-8585. JP 2001-52721 A. Japanese Patent Laid-Open No. 2003-282084. JP 2001-216977 A.

  As described above, conventionally, fuel cell separators are particularly required to have high conductivity, resistance to corrosion, and low cost. For this reason, molding-type carbon materials that do not require a cutting process are attracting attention and are being developed. However, in order to develop high conductivity, it is necessary to significantly increase the filling amount of the conductivity imparting material, but there is a limit to reducing the resin content in order to maintain moldability, High conductivity could not be obtained.

  Moreover, as a result of high filling with the conductivity imparting material, the contact resistance of the molded body deteriorates due to the influence of the surface smoothness being impaired, the surface becoming hard, and the like, and the material was brittle. In addition, when the surface of the molded body is covered with the binder resin and the contact resistance is deteriorated, the surface is ground.

  Further, in order to obtain high conductivity, including a firing step in which the molded body is heated at a high temperature of 1000 to 3000 ° C. for a long time, the time required for the production becomes longer, and the production process becomes complicated and the cost is reduced. There was a problem of rising.

  On the other hand, in the case of a separator having a multilayer structure, adhesion at the interface with a different layer is hardly a problem.

An object of the present invention is to provide a separator for a fuel cell and a method for producing the same, which have solved the above-mentioned drawbacks of the prior art.
Another object of the present invention is to provide a separator for a fuel cell having a multilayer structure with particularly low contact resistance and penetration resistance and a method for producing the same.

  As a result of intensive studies, the inventors have made the surface layer a low elastic modulus layer having specific physical properties, and two or more layers provided with a high elastic modulus layer having specific physical properties as a layer other than the low elastic modulus layer. It has been found that by using a multilayer structure, a fuel cell separator having low contact resistance and low penetration resistance can be realized, and the present invention has been completed.

  As a result of further research based on the above findings, the present inventor has made the composition of each layer described above contain the same type of polymer, or a polymer that is a compatible polymer pair, thereby improving the adhesion at the layer interface. It has been found that contact resistance and penetration resistance can be further reduced.

  The inventor has also found that a separator for a fuel cell having a higher conductivity and a lower contact resistance can be obtained by using a composition containing a carbonaceous material containing boron and a low elastic modulus resin binder in the surface layer. I found it.

  That is, the present invention includes, for example, the following items [1] to [16].

[1] A low elastic modulus layer (A) having a property that one or both surface layers have a flexural modulus of 1.0 × 10 ^{1 to} 6.0 × 10 ³ MPa and a bending strain of 1% or more; ) A separator for a fuel cell, wherein at least one layer other than the layer includes at least two layers of a high elastic modulus layer (B) having a property of exceeding a flexural modulus of 6.0 × 10 ³ MPa.

  [2] The fuel cell separator according to [1], wherein the A layer has a thickness of 0.5 mm or less and the B layer has a thickness of 0.05 to 2 mm.

  [3] The layer structure consists of A layer / B layer / A layer, the total thickness is 0.2 to 3 mm, and the thickness ratio A / B of the A layer and the B layer is 0.001 to 1. The fuel cell separator according to any one of [1] or [2].

  [4] The A layer and / or the B layer is a conductive resin composite material including (a) 40 to 2% by mass of a resin composition binder and (b) 60 to 98% by mass of a conductive substance. 3] The fuel cell separator according to any one of 3).

  [5] The component (a) of the A layer is composed of a thermoplastic or thermosetting resin composition containing two or more components including 20 to 99% by mass of the elastomer, and the component (a) of the B layer has a melting point of 100 ° C. or higher. [4] The fuel cell separator according to [4], which is a thermoplastic or thermosetting resin composition containing at least one crystalline polymer having an amorphous polymer and / or an amorphous polymer having a glass transition point of 100 ° C or higher.

  [6] The fuel cell according to [4], wherein the component (a) constituting the A layer and the B layer contains at least one kind of the same polymer or a component that is a compatible polymer pair in each layer. Separator for use.

  [7] The composition according to [4] or [5], wherein the component (a) includes at least one selected from the group consisting of phenol resin, epoxy resin, vinyl ester resin, allyl ester resin, and 1,2-polybutadiene. Fuel cell separator.

  [8] The fuel cell separator according to [4] or [5], wherein the component (a) is at least one resin composition selected from the group consisting of polyolefin, polyphenyl sulfide, fluororesin, polyamide, and polyacetal.

  [9] (a) Component is hydrogenated styrene butadiene rubber (H-SBR), styrene / ethylene butylene / styrene block copolymer (SEBS), styrene / ethylene propylene / styrene block copolymer (SEPS), olefin crystal / ethylene butylene / olefin Crystal block copolymer (SEPS), styrene / ethylene butylene / olefin crystal block copolymer (CEBC), styrene / isoprene / styrene block copolymer (SIS) and at least one selected from the group consisting of styrene / butadiene / styrene block copolymer (SBS) And a separator for a fuel cell according to [4], comprising a polyolefin composition.

  [10] The fuel cell separator according to [4], wherein the component (a) contains polyvinylidene fluoride and a soft acrylic resin.

  [11] The component [b] is at least one selected from the group consisting of a metal material, a carbonaceous material, a conductive polymer, a metal-coated filler, and a metal oxide. 10] The fuel cell separator according to any one of [10].

  [12] The fuel cell separator according to any one of [1] to [10], wherein the component (b) is a carbonaceous material containing 0.05 to 5% by mass of boron.

  [13] The fuel cell separator according to any one of [4] to [12], wherein the component (b) contains 0.1 to 50% by mass of vapor grown carbon fiber and / or carbon nanotube. .

  [14] The fuel cell separator according to [13], wherein the vapor grown carbon fiber or the carbon nanotube contains 0.05 to 5% by mass of boron.

  [15] The low elastic modulus layer (A) and the high elastic modulus layer (B) formed into a sheet are laminated using at least one molding method from roll rolling molding, compression molding, and stamping molding, And the manufacturing method of the separator for fuel cells in any one of [1] thru | or [3] characterized by forming a groove | channel on both surfaces of a laminated body.

  [16] A sheet-like laminate in which the low elastic modulus layer (A) and the high elastic modulus layer (B) are formed by using at least one molding method among multilayer extrusion molding, multilayer injection molding, compression molding or roll rolling. The groove is formed on both sides of the laminate by either compression molding or stamping molding of the integrated sheet, and the fuel cell according to any one of [1] to [3] Separator manufacturing method.

  The fuel cell separator of the present invention is useful because of its low contact resistance and low penetration resistance and excellent properties as a separator. Moreover, since the groove | channel can be formed in both surfaces by the compression molding or stamping shaping | molding etc. after laminating | stacking on a sheet form, the manufacturing method of this invention can provide the separator for fuel cells at low cost.

  Hereinafter, the present invention will be described more specifically with reference to the drawings as necessary. In the following description, “parts” and “%” representing the quantity ratio are based on mass unless otherwise specified.

(Separator for fuel cell)
The separator for a fuel cell of the present invention has a low elastic modulus layer (one or both surface layers) having a property that a flexural modulus is 1.0 × 10 ^{1 to} 6.0 × 10 ³ MPa and a flexural strain is 1% or more ( A) and at least one layer other than the layer (A) include at least two layers of a high elastic modulus layer (B) having a property exceeding a flexural modulus of 6.0 × 10 ³ MPa. A typical embodiment of the fuel cell separator of the present invention is shown in the schematic cross-sectional views of FIGS. In these drawings, the fuel cell separator is a multilayer structure including at least two layers, one or both of the surface layers including the low elastic modulus layer 1 and the high elastic modulus layer 2.

(Flexural modulus)
The bending elastic modulus of the low elastic modulus layer (A) of the present invention is 1.0 × 10 ^{1 to} 6.0 × 10 ³ MPa, more preferably 2.0 × 10 ^{1 to} 5.5 × 10 ³ MPa. Yes, more preferably 3.0 × 10 ^{1 to} 5.0 × 10 ³ MPa. If the flexural modulus is less than 1.0 × 10 ¹ MPa, the fuel cell stack tends to be deformed and the groove tends to be crushed. On the other hand, when the flexural modulus exceeds 6.0 × 10 ³ MPa, the surface is hard and the contact resistance with the gas diffusion electrode, separator, and current collector tends to increase.

  The bending strain of the low elastic modulus layer (A) is 1% or more, more preferably 1.2% or more, and further preferably 1.4% or more. If the bending strain is less than 1%, cracks tend to enter the separator surface.

The high elastic modulus layer (B) of the present invention has a flexural modulus exceeding 6.0 × 10 ³ MPa, more preferably 6.5 × 10 ³ MPa or more, and even more preferably 7.0 ×. 10 ³ MPa or more. If the flexural modulus is 6.0 × 10 ³ MPa or less, there may be a problem in tightening the fuel cell stack.

(Thickness of each layer)
The thickness of the A layer of the present invention is preferably 0.5 mm or less. More preferably, it is 0.4 mm or less, More preferably, it is 0.3 mm or less. If the thickness of the A layer exceeds 0.5 mm, the groove tends to be crushed by tightening the stack.

  The thickness of the B layer of the present invention is preferably 0.05 to 2 mm, more preferably 0.07 to 1.8 mm, and still more preferably 0.09 to 1.6 mm. If the thickness of the B layer is less than 0.05 mm, the gas barrier property tends to be low. On the other hand, when the thickness of the B layer exceeds 2 mm, the resistance in the penetration direction tends to increase.

  The total thickness of the multilayer structure is preferably 0.2 to 3 mm, more preferably 0.2 to 2.8 mm, and still more preferably 0.25 to 2.6 mm. If it is less than 0.2 mm, it is difficult to ensure the depth of the groove, and if it exceeds 3 mm, the conductivity in the penetration direction is deteriorated, which is not preferable.

  The thickness ratio A / B between the low elastic modulus layer (A) and the high elastic modulus layer (B) is preferably 0.001 to 1, more preferably 0.05 to 1, and still more preferably 0.05 to 0. .8. If this thickness ratio A / B is less than 0.001, the thickness of the low elastic modulus layer is too thin, and the effect of reducing contact resistance may be reduced. On the other hand, when the thickness ratio A / B is more than 1, creeping tends to occur.

  Regarding the thickness measurement method in the present invention, for example, using a micrometer capable of measuring to a measurement accuracy of 0.01 mm, the sample plane is divided into 20 parts, and the average value is obtained by measuring the 20 points to obtain the thickness. Although it can measure, it is not limited to this.

(Low elastic modulus layer and / or high elastic modulus layer)
In the present invention, the low elastic modulus layer and / or the high elastic modulus layer is preferably a conductive resin composite containing (a) a resin composition binder and (b) a conductive substance. Without the resin composition binder, it is difficult to mold, and without the conductive material, it is difficult to function as a separator.

  In the present invention, the composition ratio of the component (a) and the component (b) is preferably 40 to 2% by mass for the component (a) and 60 to 98% by mass for the component (b). More preferably, the component (a) is 30 to 5% by mass, and the component (b) is 70 to 95% by mass. More preferably, the component (a) is 25 to 5% by mass, and the component (b) is 75 to 95% by mass. If the component (a) is less than 2% by mass, the moldability tends to deteriorate, such being undesirable. On the other hand, when the component (a) exceeds 40% by mass, the volume resistivity tends to be 1 Ωcm or more, which is not preferable.

((A) component)
The component (a) in the present invention preferably contains a thermosetting resin composition and / or a thermoplastic resin composition. In particular, the low elastic modulus layer is preferably made of a conductive composite material in which a conductive material is filled in a two or more resin composition binder containing an elastomer component. The low elastic modulus layer preferably contains an elastomer component in an amount of 20 to 99% by mass, more preferably 25 to 95% by mass, and still more preferably 30 to 95% by mass.

(Elastomer)
In the present invention, an elastomer refers to a polymer having rubber-like elasticity near normal temperature. Examples of the elastomer include acrylonitrile butadiene rubber, hydrogenated nitrile rubber, styrene butadiene rubber, ethylene propylene rubber, ethylene propylene diene terpolymer rubber, ethylene butadiene rubber, fluorine rubber, isoprene rubber, silicone rubber, acrylic rubber, and butadiene. Rubber, High styrene rubber, Chloroprene rubber, Urethane rubber, Polyether special rubber, Tetrafluoroethylene / propylene rubber, Epichlorohydrin rubber, Norbornene rubber, Butyl rubber, Styrenic thermoplastic elastomer, Olefin thermoplastic elastomer, Urethane Thermoplastic elastomer, polyester-based thermoplastic elastomer, polyamide-based thermoplastic elastomer, 1,2-polybutadiene-based thermoplastic elastomer, fluorine-based thermoplastic elastomer Sutoma include those by 1 to 2 kinds or more thereof selected from among such soft acrylic resin.

  Among these, acrylonitrile butadiene rubber, hydrogenated nitrile rubber, styrene butadiene rubber, ethylene propylene rubber, ethylene propylene diene terpolymer rubber, ethylene butadiene rubber, isoprene rubber, butadiene rubber, acrylic rubber, styrene thermoplastic elastomer, olefin Of these, thermoplastic thermoplastic elastomers, 1,2-polybutadiene thermoplastic elastomers, fluorine thermoplastic elastomers, and soft acrylic resins are preferred.

(High modulus layer)
On the other hand, the high elastic modulus layer is conductive with a binder of a resin composition containing at least one crystalline polymer having a melting point of 100 ° C. or higher and / or an amorphous polymer having a glass transition point of 100 ° C. or higher. It is preferable that the material is highly filled. The melting point and glass transition point are more preferably 105 ° C or higher, and still more preferably 110 ° C or higher. When the melting point and the glass transition point are less than 100 ° C., the fuel cell tends to cause a problem in durability.

  About the measuring method of said melting | fusing point and a glass transition point, based on DSC method of JISK7121, for example, it can measure using Perkin-Elmer company make (DSC7), However, It is not limited to this Absent.

(Other ingredients)
In the separator having a multilayer structure as in the present invention, interfacial adhesion is particularly important. Therefore, it is preferable that the components of the low elastic modulus layer and the high elastic modulus layer contain the same polymer or a compatible polymer pair in each layer to improve the interfacial strength and adhesion.

  The same type of polymer is a polymer having the same basic molecular structure that can be entangled in a molecular form. In the present invention, it is preferable that the same polymer is contained in each of the A layer and the B layer. On the other hand, the compatible polymer pair is a heterogeneous polymer that is difficult to be completely mixed in a molecular form, but a part of the molecular structure is compatible and can be partially entangled in a molecular form. Or a combination that can be partially molecularly entangled with the aid of a compatibilizer. For example, two types of polymers having part of the same molecular structure are included in each of the A layer and the B layer. Moreover, when using a compatibilizing agent, it is preferable to include the same compatibilizing agent in both the A layer and the B layer.

(Components with adhesive functional groups)
Furthermore, for the purpose of improving the strength of the interface, a component having a functional group capable of adhering to each layer by a chemical reaction can be contained as necessary. Examples of such adhesive functional groups include hydroxyl groups, carboxyl groups, amino groups, epoxy groups, isocyanate groups, glycidyl methacrylate groups, carbonyl groups, acrylic groups, maleic anhydride groups, silyl groups, and amine functional groups. Examples thereof include, but are not limited to, polymers and monomers. By containing these components, a technique for strengthening the interface is performed, and the interface peeling due to the thermal history can be more effectively suppressed.

(Thermosetting resin)
In the present invention, as the thermosetting resin, phenol resin, unsaturated polyester, epoxy resin, vinyl ester resin, alkyd resin, acrylic resin, melamine resin, xylene resin, guanamine resin, diallyl phthalate resin, allyl ester resin, furan resin Imide resin, urethane resin, urea resin and the like. Among these, one or more thermosetting resins selected from phenol resin, unsaturated polyester, epoxy resin, vinyl ester resin, allyl ester resin, and 1,2-polybutadiene are preferable.

  In particular, in a field where airtightness is required, it is preferable to select a combination of an epoxy resin and a phenol resin, unsaturated polyester, vinyl ester resin, allyl ester resin, 1,2-polybutadiene, or the like. By using these resins, it becomes easier to obtain a molded product having high airtightness without voids in the cured product.

  Furthermore, when heat resistance, acid resistance, etc. are required, a resin having a molecular skeleton such as bisphenol A type, novolak type, or cresol novolak type, or a resin having an olefin molecular skeleton is preferable. For example, epoxy resin, phenol resin, vinyl ester resin, 1,2-polybutadiene, etc. are preferable.

(Thermoplastic resin)
Examples of the thermoplastic resin of the present invention include acrylonitrile butadiene styrene copolymer, polystyrene, acrylic resin, polyvinyl chloride, polyimide, liquid crystal polymer, polyether ether ketone, fluororesin, polyolefin, polyacetal, polyamide, polyethylene terephthalate, polybutylene terephthalate. , Polycarbonate, polycycloolefin, polyphenylene sulfide, polyether sulfone, polyphenylene oxide, polyphenylene sulfone and the like.

  Among these, polyolefin having a melting point of 100 ° C. or higher, fluororesin, polybutylene terephthalate, polyphenylene sulfide, liquid crystal polymer, polyether ether ketone, polycycloolefin, polyether sulfone, and polycarbonate or polystyrene having a glass transition point of 100 ° C. or higher. One or more thermoplastic resins selected from polyphenylene oxide are preferred.

(Combination of thermoplastic resin and elastomer)
As the combination of the thermoplastic resin and the elastomer in the component (a) of the layer A of the present invention, copolymerization of polystyrene and polybutadiene, copolymerization of polystyrene and isoprene rubber, mixing of polyolefin and styrene thermoplastic elastomer, polyvinylidene fluoride And acrylic resin, polyphenylene sulfide and maleic anhydride modified styrenic thermoplastic elastomer, other copolymer of thermoplastic resin and elastomer component, and heat using compatibilizer or surfactant A polymer alloy having a microphase separation structure of a plastic resin and an elastomer component is preferable.

  Among these, a combination selected from polyolefin and styrene thermoplastic elastomer, polyvinylidene fluoride and acrylic resin, polyphenylene sulfide and maleic anhydride-modified styrene thermoplastic elastomer is preferable.

(Styrenic thermoplastic elastomer)
Examples of the styrenic thermoplastic elastomer of the present invention include hydrogenated styrene butadiene rubber, styrene / ethylene butylene / styrene block copolymer, styrene / ethylene propylene / styrene block copolymer, olefin crystal / ethylene butylene / olefin crystal block copolymer, and styrene / ethylene butylene. -Olefin crystal block copolymer, styrene / isoprene / styrene block copolymer, styrene / butadiene / styrene block copolymer, and the like. Among them, hydrogenated styrene butadiene rubber, styrene / ethylene butylene / styrene block copolymer, styrene / ethylene propylene / styrene block copolymer, and modified products thereof are preferable.

(Polyolefin)
Polyolefin is a general term for hydrocarbon compounds, and examples thereof include polypropylene, polyethylene, polybutene, and polymethylpentene. Of these, polypropylene and polybutene are preferable.

(Other additives)
In addition, in component (a), if necessary, a monomer, a plasticizer, a curing agent, a curing initiator, a curing aid, a solvent, an ultraviolet stabilizer, an antioxidant, a thermal stabilizer, an antifoaming agent, A component selected from a leveling agent, a release agent, a lubricant, a water repellent, a thickener, a low shrinkage agent, a hydrophilicity imparting agent, and the like can be added.

(Method for producing component (a))
The production method of the component (a) of the present invention is not particularly limited. For example, physical methods such as solution method, emulsion method, melting method, graft polymerization method, block polymerization method, IPN (interpenetrating polymer network) method are used. The manufacturing method by chemical methods, such as these, is mentioned.

  In the case of producing component (a) by blending different polymers, a melting method is preferred. Although it does not restrict | limit especially with a melting method, The method of blending using kneading machines, such as a roll, a kneader, a Banbury mixer, an extruder, etc. are mentioned.

  Further, not only a blend of different polymers but also a compatibilizer may be interposed to lower the interfacial tension and control the microphase separation structure to obtain the desired component (a). This is more preferably produced by a reactive processing method, which is a method using a continuous extruder with a polymer reaction.

((B) component)
The component (b) of the present invention is preferably one or more combinations selected from metal materials, carbonaceous materials, conductive polymers, metal-coated fillers, or metal oxides. More preferably, it is a carbonaceous material and / or a metal material.

(Metal material)
As metal materials, Ni, Fe, Co, B, Pb, Cr, Cu, Al, Ti, Bi, Sn, W, P, Mo, Ag, Pt, Au, TiC, NbC, TiCN, TiN, CrN, TiB ₂ , any one of ZrB ₂ and Fe ₂ B, or a composite material of two or more is preferable. Further, these metal materials are used after being processed into powder or fiber.

(Carbonaceous material)
Examples of the carbonaceous material include one or more combinations selected from carbon black, carbon fiber, amorphous carbon, expanded graphite, artificial graphite, natural graphite, vapor grown carbon fiber, carbon nanotube, and fullerene. .

(Carbonaceous material containing boron)
Furthermore, it is preferable that 0.05-5 mass% of boron is contained in the carbonaceous material. If the boron content is less than 0.05% by mass, the intended highly conductive graphite powder tends to be difficult to obtain. Even if the boron content exceeds 5% by mass, it tends to be difficult to contribute to the improvement of the conductivity of the carbon material. The method for measuring the amount of boron contained in the carbonaceous material is not particularly limited, and any measurement method can be used. In the present invention, a value measured by induction plasma emission spectrometry (hereinafter abbreviated as “ICP”) or induction plasma emission spectrometry / mass spectrometry (hereinafter abbreviated as “ICP-MS”) is used. Specifically, sulfuric acid and nitric acid are added to the sample, decomposed by microwave heating (230 ° C.) (Digester method), and further decomposed by adding perchloric acid (HClO ₄ ) and diluted with water. Is applied to an ICP emission spectrometer to measure the amount of boron.

As a method for containing boron, natural graphite, artificial graphite, expanded graphite, carbon black, carbon fiber, vapor-grown carbon fiber, carbon nanotube, or the like, or a mixture of at least one of them as a boron source, B alone was added B ₄ C, BN, the _{B 2 0 3, H 3 B0} 3 or the like, by treatment graphitized at about 2,300-3,200 ° C. and mixed well, may contain boron carbonaceous material . When the boron compound is not uniformly mixed, not only the graphite powder becomes non-uniform, but also the possibility of sintering during graphitization increases. In order to uniformly mix the boron compound, it is preferable that these boron sources have a particle diameter of about 50 μm or less, preferably about 20 μm or less, and are mixed with a powder such as coke.

  When boron is not added, graphitization decreases the degree of graphitization (crystallinity), increases the lattice spacing, and tends to make it difficult to obtain highly conductive graphite powder. Further, as long as boron and / or boron compounds are mixed in graphite, the form of boron content is not particularly limited, but those existing between layers of graphite crystals, and some of carbon atoms forming graphite crystals are boron. Those substituted with atoms are also more preferred. In addition, the bond between the boron atom and the carbon atom when a part of the carbon atom is substituted with the boron atom may be any bond mode such as a covalent bond or an ionic bond.

(Carbon black)
Carbon black, which is an example of the carbonaceous material described above, includes furnaces obtained by incomplete combustion of natural gas, etc., ketjen black obtained by thermal decomposition of acetylene, acetylene black, hydrocarbon oil and natural gas. Examples thereof include thermal carbon obtained by pyrolysis of carbon and natural gas.

(Carbon fiber)
Examples of the carbon fiber include pitch systems made from heavy oil, by-product oil, coal tar, and the like, and PAN systems made from polyacrylonitrile.

(Amorphous carbon)
In order to obtain the above-mentioned amorphous carbon, there is a method in which a phenol resin is cured and baked and pulverized to obtain a powder, or a method in which a phenol resin is cured in the form of a spherical, irregularly shaped powder and baked. is there. In order to obtain amorphous carbon having high conductivity, it is suitable to perform heat treatment at 2000 ° C. or higher.

(Expanded graphite powder)
The above expanded graphite powder is, for example, a strong oxidizing solution of graphite having a highly developed crystal structure such as natural graphite and pyrolytic graphite, a mixture of concentrated sulfuric acid and nitric acid, and a mixture of concentrated sulfuric acid and hydrogen peroxide. Immersion treatment to form a graphite intercalation compound, which is washed with water and then rapidly heated to pulverize the powder obtained by expanding the C-axis direction of the graphite crystal and once rolled into a sheet Powder.

(Artificial graphite)
In order to obtain the above-mentioned artificial graphite, usually coke is first produced. Coke raw material is petroleum pitch, coal pitch, or the like. These raw materials are carbonized into coke. In general, coke is converted into graphitized powder by pulverizing the coke and then graphitizing, or by pulverizing the coke itself and then pulverizing, or by adding a binder to the coke and molding and firing the product (coke and this calcined product). There is a method of pulverizing a product after combining it with a graphitization process. Since it is better that the raw material coke does not have crystals as much as possible, heat-treated at 2000 ° C. or lower, preferably 1200 ° C. or lower is suitable.

  As the graphitization method, a method using an Atchison furnace in which powder is put in a graphite crucible and directly energized, a method of heating powder with a graphite heating element, or the like can be used.

(Crushing and classification method)
For crushing coke, artificial graphite, natural graphite, etc., high-speed rotary crusher (hammer mill, pin mill, cage mill), various ball mills (rolling mill, vibration mill, planetary mill), stirring mill (bead mill, attritor, distribution pipe) Mold mills, annular mills) and the like can be used. Further, a screen mill, a turbo mill, a supermicron mill, and a jet mill, which are fine pulverizers, can be used by selecting conditions. Crush, natural graphite, and the like are pulverized using these pulverizers, and the selection of pulverization conditions at that time, and classification of the powder as necessary, control the average particle size and particle size distribution.

  As a method for classifying coke powder, artificial graphite powder, natural graphite powder, etc., any method can be used as long as separation is possible. For example, a sieving method or a forced vortex type centrifugal classifier (micron separator, turboplex, turboclassic) Airflow classifiers such as fire and super separators and inertia classifiers (improved virtual impactor and elbow jet) can be used. A wet sedimentation method or a centrifugal classification method can also be used.

(Preferred component in component B)
The component B of the present invention preferably contains 0.1 to 50% by mass of vapor grown carbon fiber and / or carbon nanotube. More preferably, it is 0.1-45 mass%, More preferably, it is 0.2-40 mass%. If it is less than 0.1% by mass, it is difficult to obtain an effect of improving the conductivity. Moreover, when it exceeds 50 mass%, there exists a tendency for a moldability to worsen.

  Further, the vapor grown carbon fiber or carbon nanotube preferably contains 0.05 to 5% by mass of boron. More preferably, it is 0.06-4 mass%, More preferably, it is 0.06-3 mass%. If it is less than 0.05% by mass, the effect of improving the conductivity by adding boron is small. In addition, when the amount exceeds 5% by mass, the amount of impurities increases, and other physical properties tend to decrease.

(Vapor grown carbon fiber)
The vapor grown carbon fiber is obtained, for example, by subjecting an organic compound such as benzene, toluene or natural gas as a raw material to a thermal decomposition reaction at 800 to 1300 ° C. with hydrogen gas in the presence of a transition metal catalyst such as ferrocene. Carbon fibers (for example, having a fiber diameter of about 0.5 to 10 μm) are preferred. Furthermore, carbon fibers obtained by graphitizing the carbon fibers at about 2300 to 3200 ° C. are preferable. More preferably, it is graphitized at about 2300 to 3200 ° C. together with a graphitization catalyst such as boron, boron carbide, beryllium, aluminum and silicon.

(carbon nanotube)
With carbon nanotubes, in recent years, not only its mechanical strength, but also field emission function and hydrogen storage function have attracted industrial attention, and further attention has been focused on magnetic function. This type of carbon nanotube is also called graphite whisker, filamentous carbon, graphite fiber, ultrafine carbon tube, carbon tube, carbon fibril, carbon microtube, carbon nanofiber, etc., and the fiber diameter is about 0.5-100 nm Stuff. Carbon nanotubes include single-walled carbon nanotubes having a single graphite film forming a tube and multi-walled carbon nanotubes having multiple layers. In the present invention, both single-walled and multi-walled carbon nanotubes can be used. However, it is preferable to use single-walled carbon nanotubes because a composition having higher conductivity and mechanical strength tends to be obtained.

  Carbon nanotubes are produced, for example, by the arc discharge method, laser evaporation method, thermal decomposition method and the like described in Saito and Itoh “Basics of Carbon Nanotubes” (pages 23-57, published by Corona, 1998), and further purity In order to increase the pH, it is obtained by purification by a hydrothermal method, a centrifugal separation method, an ultrafiltration method, an oxidation method or the like. More preferably, high temperature treatment is performed in an inert gas atmosphere at about 2300 to 3200 ° C. to remove impurities. More preferably, a high temperature treatment is performed at about 2300 to 3200 ° C. in an inert gas atmosphere together with a graphitization catalyst such as boron, boron carbide, beryllium, aluminum and silicon.

(Additive)
Furthermore, the conductive resin composition of the low elastic modulus layer and the high elastic modulus layer of the present invention is further made of glass fiber for the purpose of improving hardness, strength, conductivity, moldability, durability, weather resistance, water resistance, etc. Additives such as whiskers, metal oxides, organic fibers, UV stabilizers, antioxidants, mold release agents, lubricants, water repellents, thickeners, low shrinkage agents, hydrophilicity-imparting agents can be added. .

(Method for producing composition)
Although the manufacturing method of the conductive resin composition of the low elastic modulus layer and the high elastic modulus layer in the present invention is not particularly limited, for example, in the manufacturing method of the conductive resin composition, each of the above-described components is rolled, an extruder, It is preferable to use a mixer or a kneader generally used in the resin field such as a kneader, a Banbury mixer, a Henschel mixer, or a planetary mixer and mix them as uniformly as possible.

  Examples of the mixing method include a method in which the component (a) described above is produced in advance and then mixed with the component (b), and a method in which each component of the component (a) is kneaded in the presence of the component (b). However, it is not limited to these.

  The conductive resin composition in the present invention can be pulverized or granulated for the purpose of facilitating material supply to a molding machine or a mold after kneading or mixing. For pulverization, a homogenizer, a Willet pulverizer, a high-speed rotary pulverizer (hammer mill, pin mill, cage mill, blender) or the like can be used, and it is preferable to pulverize while cooling in order to prevent aggregation of materials. For granulation, a method of pelletizing using an extruder, a ruder, a kneader or the like, or a bread type granulator or the like is used.

(Separator for fuel cell)
In the fuel cell separator of the present invention, the low elastic modulus layer and the high elastic modulus layer are once formed into a sheet form using an extrusion molding machine, a roll molding machine, a calender molding machine, a compression molding machine or the like. Thereafter, a low elastic modulus layer and a high elastic modulus layer are laminated and integrated by using one or more molding methods of roll rolling molding, compression molding, stamping molding, and hydrogen and oxygen on both surfaces. A separator in which a groove for supplying is formed is obtained. In order to eliminate voids and air inside the separator, it is preferable to mold in a vacuum state.

  In addition, the low elastic modulus layer and the high elastic modulus layer are molded into a sheet-like laminate using one or more molding methods of multilayer extrusion molding, multilayer injection molding, compression molding, or roll rolling, The integrated sheet is obtained by forming grooves for supplying hydrogen and oxygen on both sides of the separator by either compression molding or stamping. In order to eliminate voids and air inside the separator, it is preferable to mold in a vacuum state.

  Furthermore, after the integrated sheet is cut or punched to a desired size, one sheet or two or more sheets are lined up in parallel in the mold, or inserted one after another, and molded by a compression molding machine. Can also obtain a molded body. In order to obtain a good product having no defects, it is preferable to evacuate the cavity.

  Examples The present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.

  A method for measuring the physical properties of the laminate is shown below.

  The volume resistivity was measured by a four-probe method according to JIS K7194.

(Contact resistance)
The contact resistance was calculated by the following equation 1 by measuring three resistance values of the contact resistance value (Rc) with carbon paper (TGP-H-060 manufactured by Toray) by the four-terminal method shown in FIG.
Specifically, a test piece (20 mm × 20 mm × 1 mm), carbon paper (20 mm × 20 mm × 0.19 mm), a gold-plated brass plate (20 mm × 20 mm × 0.5 mm) is used, and the test piece is made of the carbon paper. Sandwiched between two gold-plated brass plates, pressurized uniformly at 2 MPa, a 1 A constant current is passed between the gold-plated brass plates in the penetration direction, and the resistance (R ₁ ) is calculated by measuring the voltage. . Similarly, the resistance (R ₂ ) is calculated by sandwiching three pieces of carbon paper between two gold-plated brass plates and performing the same measurement. Further, the resistance (R ₃ ) was calculated by sandwiching two pieces of carbon paper between two gold-plated brass plates and performing the same measurement. From the above three resistance values, the contact resistance value between the carbon paper and the test piece is calculated by Equation 1.

[Formula 1] Rc = (R ₁ + R ₂ −2R ₃ ) × S / 2
Rc: contact resistance (Ωcm ² ), S: contact area (cm ² )
R ₁ : Resistance calculated from measurement 1 (Ω)
R ₂ : Resistance (Ω) calculated by measurement 2
R ₃ : Resistance (Ω) calculated by measurement 3

(Penetration resistance)
The penetration resistance is measured by the four-terminal method shown in FIG. Specifically, four test pieces (50 mm x 50 mm x 2 mm) are stacked, sandwiched between two gold-plated brass plates, and uniformly pressurized at 2 MPa, and a constant current of 1 A is passed between the gold-plated brass plates in the penetration direction. Then, the resistance (R ₁ ) is calculated by measuring the voltage. Similarly, two test pieces are stacked and sandwiched between gold-plated brass plates, and the resistance (R ₂ ) is calculated by performing the same measurement. Furthermore, as shown in Formula 2, the resistance (R ₁ ) and resistance (R ₂ ) are taken, multiplied by the contact area (S), and divided by the thickness (t) of the two test pieces to reduce the penetration resistance. calculate.

[Formula 2] Rt = (R ₁ −R ₂ ) × S / t
Rt: penetration resistance (Ωcm), S: contact area (cm ² )
R ₁ : Resistance calculated from measurement 1 (Ω)
R ₂ : Resistance (Ω) calculated by measurement 2
t: Thickness (cm) of two test pieces

(Bending strength, etc.)
The bending strength, bending elastic modulus and bending strain were measured using an autograph (AG-10kNI) manufactured by Shimadzu Corporation. A test piece (80 mm × 10 mm × 1.5 mm) was measured by a JIS K6911 method by a three-point bending strength measurement method under a span interval of 64 mm and a bending speed of 1 mm / min.

  Next, the materials used are shown below.

(A) Component: The resin composition described in Table 1 was used. The unit of the composition ratio in the table is expressed by mass%.

(B) Component: Conductive substance <b1>: Boron-containing graphite fine powder MC coke manufactured by MC Carbon Co., which is non-acicular coke, is 2 mm to 3 mm or less in size with a pulverizer (manufactured by Hosokawa Micron Corporation). Coarsely ground. The coarsely pulverized product was finely pulverized with a jet mill (IDS2UR, manufactured by Nippon Pneumatic Co., Ltd.). Then, it adjusted to the desired particle size by classification. For removing particles of 5 μm or less, air classification was performed using a turbo classifier (TC15N, manufactured by Nisshin Engineering Co., Ltd.). 0.6 kg of boron carbide (B ₄ C) was added to 14.4 kg of a part of this finely pulverized product, and mixed at 800 rpm with a Henschel mixer for 5 minutes. This was sealed in a graphite crucible with a lid having an inner diameter of 40 cm and a volume of 40 liters, placed in a graphitization furnace using a graphite heater, and graphitized at a temperature of 2900 ° C. in an argon gas atmosphere. After standing to cool, the powder was taken out to obtain 14 kg of powder. The obtained graphite fine powder had an average particle size of 20.5 μm and a B content of 1.9% by mass.

<B2>: Mixture of vapor grown carbon fiber (hereinafter abbreviated as “VGCF”, Showa Denko registered trademark) and b1 (graphite fine powder) 95% by mass of b1 component and 5% by mass of VGCF were mixed in a Henschel mixer. The average particle diameter of the obtained carbon material mixture was 12.4 μm and the B content was 1.3% by mass.

  As the vapor grown carbon fiber, VGCF-G (fiber diameter 0.1 to 0.3 μm, fiber length 10 to 50 μm) manufactured by Showa Denko Co., Ltd. was used.

<B3>: Mixture of carbon nanotubes (hereinafter abbreviated as “CNT”) and b1 (graphite fine powder) 95% by mass of the component b1 and 5% by mass of CNT were mixed with a Henschel mixer. The obtained carbon material mixture had an average particle size of 9.2 μm and a B content of 1.2% by mass. Carbon nanotubes were obtained by the following method.

  A graphite rod having a diameter of 6 mm and a length of 50 mm is drilled with a hole having a diameter of 3 mm and a depth of 30 mm along the central axis from the tip, and a rhodium (Rh): platinum (Pt): graphite (C) mass ratio is 1 in this hole. It was packed as a 1: 1 mixed powder to prepare an anode. On the other hand, a cathode having a diameter of 13 mm and a length of 30 mm made of graphite having a purity of 99.98% by mass was produced. These electrodes were placed opposite to the reaction vessel and connected to a DC power source. Then, the inside of the reaction vessel was replaced with helium gas having a purity of 99.9% by volume, and DC arc discharge was performed. Thereafter, soot (chamber soot) adhering to the inner wall of the reaction vessel and soot deposited on the cathode (cathode soot) were collected. The pressure and current in the reaction vessel were 600 Torr and 70A. During the reaction, the operation was performed so that the gap between the anode and the cathode was always 1 to 2 mm.

  The collected soot was ultrasonically dispersed in a 1: 1 mixed solvent of water and ethanol, the dispersion was recovered, and the solvent was removed with a rotary evaporator. The sample was ultrasonically dispersed in a 0.1% aqueous solution of benzalkonium chloride, which is a cationic surfactant, and then centrifuged at 5000 rpm for 30 minutes to recover the dispersion. Further, the dispersion was purified by heat treatment in air at 350 ° C. for 5 hours to obtain carbon nanotubes having a fiber diameter of 1 nm to 10 nm and a fiber length of 0.05 to 5 μm.

<A1-A6: Low elastic modulus composition, B1, B2: High elastic modulus composition>:
The composition of the low elastic modulus layer and the high elastic modulus layer was produced by the following method.
The raw materials having the composition shown in Table 1 were kneaded for 7 minutes at a temperature of 200 ° C. and 45 rpm using a lab plast mill (manufactured by Toyo Seiki Seisakusho, Model 50C150). The kneaded product is put into a mold capable of forming a flat plate of 100 mm × 100 mm × 1.5 mm, heated at 230 ° C. for 3 minutes with a 50 t compression molding machine, and heated under pressure at 15 MPa for 3 minutes, and then cooled. The compact was obtained by cooling for 2 minutes under the conditions of a temperature of 25 ° C. and a pressure of 15 MPa using a press. The physical properties of each molded body are shown in Table 2.

Example 1
The composition A1 and composition B1 shown in Table 2 above were formed into a sheet having a width of 100 mm at a temperature of 250 ° C. and 40 rpm using a φ40 single-screw extruder (Tanabe Plastics Machinery Co., Ltd., VS40 / 26 vent type). The sheet was rolled with a roll at a temperature of 180 ° C., and the composition A1 was adjusted to a thickness of 0.6 mm and the composition B1 was adjusted to a thickness of 1.8 mm. Thereafter, the layers are laminated in the order of A1 / B1 / A1, put into a mold capable of forming a flat plate of 100 mm × 100 mm × 1.5 mm, and after 3 minutes of preheating at 240 ° C. using a 50 t compression molding machine, 3 at a pressure of 15 MPa. The mixture was heated under pressure for 1 minute, and then cooled for 2 minutes using a cooling press at a temperature of 25 ° C. and a pressure of 15 MPa to obtain a molded body. The physical property measurement results of the obtained laminate are shown in Table 3.

Examples 2-5
Using a φ40 single screw extruder (Tanabe Plastics Machinery Co., Ltd., VS40 / 26 vent type), a sheet having a width of 100 mm at a temperature of 250 ° C. and 40 rpm is used for the compositions A2 to A5 and the composition B1 shown in Table 2 above. It shape | molded and the sheet | seat was rolled at the temperature of 180 degreeC with the roll, composition A2-A5 adjusted to 0.4 mm, and composition B1 adjusted to 2.2 mm. Then, A2 / B1 / A2, A3 / B1 / A3, A4 / B1 / A4, A5 / B1 / A5 are stacked in this order, and put into a mold that can make a flat plate of 100mm x 100mm x 1.5mm. , Using a 50t compression molding machine at a temperature of 240 ° C. for 3 minutes after preheating, then pressurizing and heating at a pressure of 15 MPa for 3 minutes, and then using a cooling press to cool at a temperature of 25 ° C. and a pressure of 15 MPa for 2 minutes. Got. The physical property measurement results of the obtained laminate are shown in Table 3.

Example 6
The composition A6 and the composition B2 shown in Table 2 above were formed into a sheet having a width of 100 mm at a temperature of 220 ° C. and 40 rpm using a φ40 single-screw extruder (Tanabe Plastics Machinery Co., Ltd., VS40 / 26 vent type). The sheet was rolled with a roll at a temperature of 185 ° C., and the composition A6 was adjusted to a thickness of 0.4 mm, and the composition B2 was adjusted to a thickness of 2.2 mm. Thereafter, the layers are laminated in the order of A6 / B2 / A6, put into a mold capable of forming a flat plate of 100 mm × 100 mm × 1.5 mm, and heated at 220 ° C. for 3 minutes using a 50 t compression molding machine, and 3 at a pressure of 15 MPa. The mixture was heated under pressure for 1 minute, and then cooled for 2 minutes using a cooling press at a temperature of 25 ° C. and a pressure of 15 MPa to obtain a molded body. The physical property measurement results of the obtained laminate are shown in Table 3.

Comparative Example 1
The composition A1 and composition B1 shown in Table 2 above were formed into a sheet having a width of 100 mm at a temperature of 250 ° C. and 40 rpm using a φ40 single-screw extruder (Tanabe Plastics Machinery Co., Ltd., VS40 / 26 vent type). The sheet was rolled with a roll at a temperature of 180 ° C., and the composition A1 was adjusted to a thickness of 1.2 mm, and the composition B1 was adjusted to a thickness of 0.6 mm. Thereafter, the layers are laminated in the order of B1 / A1 / B1, put into a mold capable of forming a flat plate of 100 mm × 100 mm × 1.5 mm, and after 3 minutes of preheating at 240 ° C. using a 50 t compression molding machine, 3 at a pressure of 15 MPa. The mixture was heated under pressure for 1 minute, and then cooled for 2 minutes using a cooling press at a temperature of 25 ° C. and a pressure of 15 MPa to obtain a molded body. The physical property measurement results of the obtained laminate are shown in Table 3.

Comparative Example 2
Using compositions φ1 and B2 shown in Table 2 above using a φ40 single-screw extruder (Tanabe Plastics Machinery Co., Ltd., VS40 / 26 vent type), B1 is 250 ° C., B2 is 220 ° C., and the number of revolutions A sheet having a width of 100 mm was formed at 40 rpm, and the sheet was rolled with a roll at a temperature of 180 ° C., and the composition B2 was adjusted to a thickness of 0.4 mm, and the composition B1 was adjusted to a thickness of 2.2 mm. Thereafter, the layers were laminated in the order of B2 / B1 / B2, respectively, and put into a mold capable of forming a flat plate of 100 mm × 100 mm × 1.5 mm, using a 50 t compression molding machine, temperature 230 ° C., preheating 3 minutes, pressure 15 MPa And then heated under pressure for 3 minutes, and then cooled for 2 minutes under the conditions of a temperature of 25 ° C. and a pressure of 15 MPa using a cooling press to obtain a molded body. The physical property measurement results of the obtained laminate are shown in Table 3.

Comparative Example 3
The composition A2 and composition A6 shown in Table 2 above were prepared using a φ40 single screw extruder (Tanabe Plastics Machinery Co., Ltd. VS40 / 26 vent type), A2 at a temperature of 250 ° C., A6 at a temperature of 220 ° C., A sheet having a width of 100 mm was formed at a rotation speed of 40 rpm, and the sheet was rolled with a roll at a temperature of 180 ° C., and the composition A2 was adjusted to a thickness of 0.4 mm, and the composition A6 was adjusted to a thickness of 2.2 mm. After that, they are laminated in the order of A2 / A6 / A2, respectively, and put into a mold capable of forming a flat plate of 100 mm × 100 mm × 1.5 mm, using a 50 t compression molding machine, temperature 230 ° C., preheating 3 minutes, pressure 15 MPa And then heated under pressure for 3 minutes, and then cooled for 2 minutes under the conditions of a temperature of 25 ° C. and a pressure of 15 MPa using a cooling press to obtain a molded body. The physical property measurement results of the obtained laminate are shown in Table 3.

  From Table 3 showing the results of the above Examples and Comparative Examples, the laminate of the present invention in which the surface is a low elastic modulus composition and the middle is a high elastic modulus composition is excellent in conductivity, and particularly improves the penetration resistance. I came to let you.

  As in Comparative Example 1, when the surface was covered with a thick and hard layer, the penetration resistance deteriorated.

  In addition, as in Comparative Examples 2 and 3, the laminate of different materials peeled off at the interface, resulting in poor penetration resistance.

Example 7
The laminate of Example 5 was put into a compression molding machine into a mold capable of forming a flat plate having a size of 200 × 120 × 1.5 mm, a groove width of 1 mm, a groove depth of 0.5 mm on both sides, and 380 t. Using a compression molding machine, pressurize and heat at a mold temperature of 230 ° C. under a pressure of 50 MPa for 3 minutes, then cool the mold temperature to 100 ° C., with a double-sided groove and a volume resistivity of 6.8 mΩcm, through A separator plate for a fuel cell having a resistance of 7.2 mΩcm, a contact resistance of 2.9 mΩcm ² , a thermal conductivity of 19 W / m · K, and an air permeability of 4.3 × 10 ⁻⁹ cm ² / sec was obtained.

It is a schematic cross section which shows one example of the separator of this invention. It is a schematic cross section which shows the other example of the separator of this invention. It is a schematic cross section which shows the other example of the separator of this invention. It is a schematic cross section which shows an example of the measuring method of contact resistance. It is a schematic cross section which shows an example of the measuring method of penetration resistance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Low elastic modulus layer 2 High elastic modulus layer 11 Carbon paper 12 Test piece 13 Gold plated brass 14 Constant current generator 15 Voltmeter 21 Test piece 22 Gold plated brass 23 Constant current generator 24 Voltmeter

Claims (16)

A low elastic modulus layer (A) having a single or double-sided surface layer having a flexural modulus of 1.0 × 10 ^{1 to} 6.0 × 10 ³ MPa and a bending strain of 1% or more, and other than the (A) layer A fuel cell separator comprising at least one layer of at least two layers including a high elastic modulus layer (B) having a property of exceeding a flexural modulus of 6.0 × 10 ³ MPa.   The fuel cell separator according to claim 1, wherein the thickness of the A layer is 0.5 mm or less and the thickness of the B layer is 0.05 to 2 mm.   The layer structure is composed of A layer / B layer / A layer, the total thickness is 0.2 to 3 mm, and the thickness ratio A / B of the A layer and the B layer is 0.001 to 1. The fuel cell separator according to claim 2.   The A layer and / or the B layer is a conductive resin composite material comprising (a) 40-2% by mass of a resin composition binder and (b) 60-98% by mass of a conductive substance. 2. A fuel cell separator according to item 1.   The component (a) of the A layer is composed of a thermoplastic or thermosetting resin composition containing two or more components including 20 to 99% by mass of an elastomer, and the component (a) of the B layer is a crystal having a melting point of 100 ° C. or higher. The fuel cell separator according to claim 4, which is a thermoplastic or thermosetting resin composition containing at least one kind of a crystalline polymer and / or an amorphous polymer having a glass transition point of 100 ° C. or higher.   5. The fuel cell separator according to claim 4, wherein the component (a) constituting the A layer and the B layer contains at least one kind of a homopolymer or a compatible polymer pair.   6. The fuel cell according to claim 4 or 5, wherein the component (a) is a composition containing at least one selected from the group consisting of phenol resin, epoxy resin, vinyl ester resin, allyl ester resin, and 1,2-polybutadiene. Separator.   6. The fuel cell separator according to claim 4 or 5, wherein the component (a) is at least one resin composition selected from the group consisting of polyolefin, polyphenyl sulfide, fluororesin, polyamide, and polyacetal. (A) Component is hydrogenated styrene butadiene rubber, styrene / ethylene butylene / styrene block copolymer, styrene / ethylene propylene / styrene block copolymer, olefin crystal / ethylene butylene / olefin crystal block copolymer, styrene / ethylene butylene / olefin crystal block copolymer, 5. The fuel cell separator according to claim 4, comprising at least one selected from the group consisting of a styrene / isoprene / styrene block copolymer and a styrene / butadiene / styrene block copolymer and a polyolefin composition.   The fuel cell separator according to claim 4, wherein the component (a) contains polyvinylidene fluoride and a soft acrylic resin.   The fuel according to any one of claims 4 to 10, wherein the component (b) is at least one selected from the group consisting of metal materials, carbonaceous materials, conductive polymers, metal-coated fillers, and metal oxides. Battery separator.   11. The fuel cell separator according to claim 4, wherein the component (b) is a carbonaceous material containing 0.05 to 5 mass% of boron.   The fuel cell separator according to any one of claims 4 to 12, wherein the component (b) contains 0.1 to 50 mass% of vapor grown carbon fiber and / or carbon nanotube.   14. The fuel cell separator according to claim 13, wherein the vapor grown carbon fiber or the carbon nanotube contains 0.05 to 5% by mass of boron.   Laminating a low elastic modulus layer (A) and a high elastic modulus layer (B) formed into a sheet shape by using at least one molding method from roll rolling molding, compression molding or stamping molding, and laminating The method for producing a fuel cell separator according to any one of claims 1 to 3, wherein grooves are formed on both sides of the body.   The low elastic modulus layer (A) and the high elastic modulus layer (B) are molded into a sheet-like laminate using at least one molding method from multilayer extrusion molding, multilayer injection molding, compression molding or roll rolling, 4. The fuel cell separator according to claim 1, wherein grooves are formed on both sides of the laminate by compression molding or stamping of the integrated sheet. 5. Method.