JP4628143B2 - Conductive resin composition and molded body thereof - Google Patents

Description

  The present invention relates to a conductive resin composition excellent in conductivity and toughness and good moldability, and a molded body thereof. The conductive resin composition or molded product of the present invention can be used particularly suitably for applications as a fuel cell separator.

  Conventionally, materials such as metals and carbon materials have been used for applications requiring high conductivity. Among them, carbon materials are excellent in electrical conductivity, do not corrode like metals, and are excellent in heat resistance, lubricity, thermal conductivity, durability, etc., so electronics, electrochemistry, energy, transportation equipment Has played an important role in these fields. As a result, remarkable progress has been made in composite materials made by combining carbon materials and polymer materials. As a result, such composite materials have also played a role in improving performance and functionality. In particular, the improvement in the degree of freedom of molding processability due to the combination with a polymer material is one reason why carbon materials have been developed in various fields where conductivity is required.

  Applications of carbon materials that require electrical conductivity include electronic materials such as circuit boards, resistors, laminates, and electrodes, and members such as heaters, heating device members, and dust collecting filter elements. In these applications, high heat resistance is required along with conductivity.

  On the other hand, 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. The fuel cell can generate high output power by stacking single cells composed of, for example, 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 gas impermeability capable of completely separating these gases and high conductivity to reduce the internal resistance. Furthermore, it is requested | required that it is excellent in thermal conductivity, durability, intensity | strength, etc.

  As a method of obtaining a separator that satisfies these requirements, for example, a binder is added to carbonaceous powder, heated and mixed, and then subjected to CIP molding (Cold Isostatic Pressing), followed by firing and graphitization. A method for producing a graphite part for a fuel cell in which the obtained isotropic graphite material is impregnated with a thermosetting resin, cured, and a groove is carved by cutting (Patent Document 1), paper containing carbon powder or carbon fiber A method for producing a carbon thin plate that is impregnated with a thermosetting resin, then laminated and pressure-bonded and fired (Patent Document 2), and a fuel cell separator that is injection-molded and fired with a phenol resin in a separator-shaped mold (Patent Document 3) Etc. are disclosed.

  Although these fired materials are excellent in high conductivity and heat resistance, there are problems that the bending strength is inferior, and there is also a problem that the time required for firing is long and productivity is poor. Further, when cutting is necessary, the cost is further increased.

  On the other hand, a molding method has been studied as a method that can be expected to be high in mass productivity and low in cost, but a conductive resin composition is generally used as a material applicable thereto. For example, Patent Document 4, Patent Document 5, and Patent Document 6 disclose a separator made of a thermosetting resin such as a phenol resin, graphite, and carbon.

  Patent Documents 7 and 8 disclose highly conductive resin compositions using a combination of boron-containing graphite and resin.

JP-A-8-222241. JP-A-60-161144. JP 2001-68128 A. JP 2000-182630 A. JP 2000-331690 A. JP 2001-067932 A. Japanese Patent Laid-Open No. 2002-060639. JP2003-020418A.

  As described above, the fuel cell separator is particularly required to have high conductivity, corrosion resistance, toughness, resistance to cracking, and low cost. Furthermore, if there are a lot of ionic impurities that are eluted from the separator, it causes a problem in that the performance of the electrolyte membrane is reduced or a short circuit is caused.

  On the other hand, many studies have been made on a mold type separator made of a composite material of carbon and resin, which can be expected at the lowest cost. There was a problem in the molding process.

Therefore, a carbon resin composite material comprising a combination of a carbon material doped with boron and a resin as a conductivity imparting material that has high conductivity and does not corrode has been studied.
However, during heat treatment, boron forms compounds with other elements such as nitrogen and easily attracts various impurities. Therefore, the impurities in the carbon material increase, the amount of ions eluted by hot water extraction and the like, and the interface strength with the binder resin is low, so that the durability is not sufficient.
An object of the present invention is to provide a conductive resin composition or a molded body thereof capable of solving the above-described problems in the prior art.
Another object of the present invention is to provide a conductive resin composition excellent in conductivity, less ionic impurities due to hot water extraction, and excellent in bending properties, and a molded product thereof.

  As a result of intensive studies to solve the above problems, the present inventors have found that combining a specific boron-containing carbonaceous material and a resin binder is extremely effective in solving the above problems, and such knowledge Based on this, the present invention has been completed.

That is, the present invention includes the following aspects [1] to [12], for example.
[1] (A) a conductive resin composition comprising a boron-containing carbonaceous material having a nitrogen content of 0.2% by mass or less and a sulfur content of 0.05% by mass or less and (B) a resin binder (here, The above-mentioned “mass%” is based on the mass of the boron-containing carbonaceous material containing nitrogen and sulfur.
[2] The conductive fat composition according to [1], wherein boron in the (A) boron-containing carbonaceous material is 0.01 to 5% by mass.
[3] (A) The conductive resin composition according to [1] or [2] (herein), wherein boron nitride (BN) in the boron-containing carbonaceous material is 0.5% by mass or less. The above-mentioned “mass%” is based on the mass of the boron-containing carbonaceous material containing BN).
[4] The conductive resin composition according to any one of [1] to [3] including (A) 20 to 99% by mass of a boron-containing carbonaceous material and (B) 80 to 1% by mass of a resin binder (here) The above-mentioned “mass%” is based on the total mass (100 mass%) of the component (A) and the component (B)).
[5] (A) The conductivity of water extracted by hot water at a temperature ratio of 150 ° C. for 120 hours at a mass ratio of pure water 5 to boron-containing carbonaceous material 1 is 150 μS / cm or less. The conductive resin composition according to any one of [1] to [4].
[6] (A) The boron-containing carbonaceous material has a characteristic that the powder compaction specific resistance in the pressurizing direction under a pressure of 1 MPa is 0.05 Ωcm or less [1] to [5 ] The conductive resin composition in any one of.
[7] (A) The raw material of the boron-containing carbonaceous material is coke, mesophase carbon, pitch, charcoal, resin charcoal, natural graphite, artificial graphite, expanded graphite, carbon black, carbon fiber, vapor grown carbon fiber, carbon nanotube The conductive resin composition according to any one of [1] to [7], which is a combination of one or more selected from the group consisting of amorphous carbon and fullerene.
[8] The conductive resin composition according to any one of [1] to [7], wherein the (B) resin binder contains an elastomer component in an amount of 0.5 to 80% by mass (herein the “ "Mass%" is based on the mass of the resin binder containing the elastomer component).
[9] A conductive molded article obtained by molding the conductive resin composition according to any one of [1] to [8].
[10] a volume resistivity of 0.1? Cm or less and a contact resistance is equal to or is 0.1? Cm ² or less (9) electrically conductive molded article according.
[11] A fuel cell separator using the conductive molded article according to [9] or [10].
[12] Grooves having a width of 0.1 to 2 mm and a depth of 0.1 to 1.5 mm are formed on both surfaces, the thickness of the thinnest part is 1 mm or less, the volume resistivity is 0.1 Ωcm or less, and the contact resistance is 0 The fuel cell separator as described in [11], which is 1 Ωcm ² or less.

  The resin composition of the present invention has the properties of being excellent in conductivity and bending properties and having low hot water extraction water conductivity. For this reason, the resin composition of this invention is especially useful, for example as a separator for fuel cells.

  Hereinafter, the present invention will be described more specifically with reference to the drawings as necessary.

(Resin composition)
The resin composition of the present invention includes (A) a boron-containing carbonaceous material having a nitrogen content of 0.2% by mass or less and a sulfur content of 0.05% by mass or less, and (B) a resin binder.
(Boron-containing carbonaceous material)
In the present invention, the (A) boron-containing carbonaceous material (hereinafter also referred to as “component (A)”) has a nitrogen content of 0.2 mass% or less and a sulfur content of 0.05 mass% or less. It is necessary to be. In the present invention, the nitrogen content is preferably 0.1% by mass or less and 0.0001% by mass or more and the sulfur content is 0.02% by mass or less and 0.0001% by mass or more, and further the nitrogen content is 0.05. It is particularly preferable that the content is 0.0001% by mass or more and 0.01% by mass or less and 0.0001% by mass or more. When the nitrogen component exceeds 0.2% by mass and / or the sulfur component exceeds 0.05% by mass, elution of ionic impurities in the molded body of the conductive resin composition of the present invention (particularly, a separator for a fuel cell) Is unfavorable because of the increase in the thickness and the durability becomes a problem.

(Boron)
0.01-5 mass% is preferable, as for the amount of boron in (A) component of this invention, 0.01-4 mass% is more preferable, and 0.02-4 mass% is still more preferable. If the boron content is less than 0.01% by mass, the intended highly conductive carbonaceous material may not be obtained. On the other hand, even if the boron content exceeds 5% by mass, further improvement in conductivity cannot be expected.

As a method of incorporating boron into the carbonaceous material, for example, as a boron source in the carbonaceous material, adding B alone, B ₄ C, BN, the _{B 2 0 3, H 3 B0} 3 or the like, about well mixed The method of heat-processing in the inert gas atmosphere of 0 group elements, such as 2000-3200 degreeC helium and argon, is mentioned. Use of nitrogen as an inert gas is not preferable because it combines with boron and a nitrogen content remains in the amount of carbonaceous material. Since a general carbonaceous material does not contain boron and BN is not formed, it is possible to use N ₂ as an inert gas.
If the boron compound is not uniformly mixed, not only the carbonaceous material becomes non-uniform, but also the possibility of partial sintering by heat treatment increases. In order to uniformly mix the boron compound, it is preferable to mix these boron sources in the form of powder having a particle size of about 50 μm or less, preferably about 20 μm or less.

  In addition, as long as boron and / or boron compounds are mixed in the carbonaceous material, the form of boron content is not particularly limited, but it is present between layers of graphite crystals, or part of carbon atoms forming graphite crystals. In which is substituted with a boron atom is more preferable. 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.

(BN)
In the component (A) of the present invention, BN is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, and still more preferably 0.08% by mass or less. When the content of BN exceeds 0.5% by mass, BN is hydrolyzed by high-temperature hot water and becomes an ionic impurity, which is not preferable.

(Hot water extraction)
Furthermore, the component (A) of the present invention is pure water (conductivity 2 μS / cm or less): the mass ratio of the component (A) is 5: 1, and the conductivity of water extracted by hot water at 150 ° C. for 120 hours. The rate (measured at 23 ° C.) is preferably 150 μS / cm or less. More preferably, it is 100 μS / cm or less, and still more preferably 80 μS / cm or less. If the conductivity of the hot water extraction water exceeds 150 μS / cm, it is not preferable because the durability of the molded body is lowered.

(Powder consolidation specific resistance)
Furthermore, the component (A) of the present invention preferably has a powder compaction specific resistance of the component A in the pressurizing direction of 0.05 Ωcm or less under a pressure of 1 MPa. More preferably, it is 0.04 Ωcm or less, and still more preferably 0.02 Ωcm or less. If the powder compaction specific resistance exceeds 0.05 Ωcm, the conductivity when formed into a molded product is deteriorated, which is not preferable.

(Raw material of component (A))
As the raw material of the component (A) of the present invention, coke, mesophase carbon, pitch, charcoal, resin charcoal, carbon black, carbon fiber, amorphous carbon, expanded graphite, artificial graphite, natural graphite, vapor grown carbon fiber, carbon nanotube , And one or more combinations selected from fullerenes. Among these, a combination selected from coke, mesophase carbon, carbon black, natural graphite, artificial graphite, vapor grown carbon fiber, and carbon nanotube is preferable. A combination selected from coke, mesophase carbon, carbon black, vapor grown carbon fiber, and carbon nanotube is more preferable. In order to further include boron, a raw material selected from coke, mesophase carbon, carbon black, vapor grown carbon fiber, and carbon nanotube is more preferable.

(Artificial graphite)
As a method for obtaining the above-mentioned artificial graphite, usually, first, raw materials such as petroleum pitch and coal pitch are carbonized to obtain 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. In order to keep the nitrogen content and sulfur content below a predetermined value, it is desirable to perform a heat treatment such as graphitization in an atmosphere of a group 0 inert gas such as helium or argon. In the case of a carbonaceous material that does not contain boron, there is no particular problem even if nitrogen is used as the inert gas. However, if boron is contained, it binds to nitrogen and produces BN, which is not preferable.

(Carbon black)
Carbon black, which is an example of the raw material of the above-described component A, is a furnace obtained by incomplete combustion of natural gas or the like, ketjen black obtained by thermal decomposition of acetylene, acetylene black, hydrocarbon oil or 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)
As a method of obtaining the above-mentioned amorphous carbon, there is a method of curing a phenol resin and baking treatment and pulverizing it into a powder, or a method of curing a phenol resin in a spherical, irregular shape powder and baking treatment. is there. In order to obtain highly conductive amorphous carbon, it is preferable to perform heat treatment at 2000 ° C. or higher.

(Expanded graphite powder)
As the above expanded graphite powder, for example, graphite having a highly crystallized structure such as natural graphite, pyrolytic graphite, etc., a strong oxidizing property of a mixed solution of concentrated sulfuric acid and nitric acid, a mixed solution of concentrated sulfuric acid and hydrogen peroxide solution. A graphite intercalation compound is formed by immersing in a solution, washed with water, rapidly heated, and a powder obtained by expanding the C-axis direction of the graphite crystal, or a sheet obtained by rolling it into a sheet. Examples thereof include pulverized powder.

(Vapor grown carbon fiber)
The above-mentioned vapor grown carbon fiber can be 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. It is preferable that the fiber diameter is about 0.5 to 10 μm and graphitized at about 2300 to 3200 ° C. When an inert gas is used during the thermal decomposition reaction, it is desirable to use a group 0 element gas such as argon instead of N ₂ .

(carbon nanotube)
The above-mentioned carbon nanotubes have recently attracted attention not only in their mechanical strength, but also in the field emission function and hydrogen storage function in the industry, and also in the magnetic function. Graphite whiskers, filamentous carbon, It is also called graphite fiber, ultrafine carbon tube, carbon tube, carbon fibril, carbon microtube, carbon nanofiber, etc., and has a fiber diameter of about 0.5 to 100 nm. 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, but single-walled carbon nanotubes are preferred because they tend to provide higher electrical conductivity and mechanical strength.

  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 to 57, published by Corona Publishing Co., Ltd., 1998). 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. In the present invention, it is preferable to perform high temperature treatment in an inert gas atmosphere of a group 0 element at about 2300 to 3200 ° C. in order to remove impurities.

(Granularity)
The particle size of the component (A) of the present invention may be adjusted by pulverization or classification in advance to the required particle size, or may be adjusted by pulverization or classification after heat treatment. It is preferable to adjust the particle size by grinding or the like. Grinding after heat treatment is not preferable because the modified surface is damaged.

(Crushing and classification)
For material crushing, 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 mill, annular mill), etc. 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. It grind | pulverizes using these grinders, the selection of the grinding | pulverization conditions in that case, and classification of a powder if necessary, controls an average particle diameter and a particle size distribution.

  Any method can be used as long as separation is possible. For example, a sieving method, a forced vortex type centrifugal classifier (micron separator, turboplex, turbo classifier, super separator), an inertia classifier ( Airflow classifiers such as improved birch impactors and elbow jets) can be used. A wet sedimentation method or a centrifugal classification method can also be used.

(Heat treatment)
As the heat treatment, there are a method of using an Atchison furnace in which the above raw materials and a boron source are mixed well and made uniform, and the powder is placed in a graphite crucible and energized, a method of heating the powder with a graphite heating element using a high frequency induction heating furnace, etc. Can be mentioned. The treatment temperature is about 2000 to 3200 ° C., and heat treatment is performed in an inert gas atmosphere of a group 0 element.

(Resin binder)
The (B) resin binder (hereinafter also referred to as “component (B)”) that constitutes the composition of the present invention together with the above-described (A) boron-containing carbonaceous material is generally referred to as a binder. The binder is not particularly limited as long as it is a resin, and examples of the binder include thermoplastic resins and thermosetting resins.
(Thermoplastic resin)
Examples of the thermoplastic resin include polyolefin (polyethylene, polypropylene, ethylene propylene copolymer, ethylene-based copolymer, polymethylpentene, polybutene, etc.), polystyrene (PS), polyvinyl chloride (PVC), acrylonitrile butadiene. Styrene copolymer (ABS resin), acrylic resin (PMMA), polyimide (PI), liquid crystal polymer, polyether ether ketone (PEEK), fluororesin, polyacetal (POM), polyamide (PA), polyethylene terephthalate (PET), Polybutylene terephthalate (PBT), polycarbonate (PC), cycloolefin polymer (COP), polyphenylene sulfide (PPS), polyphenylene ether (PPE), polyphenylene sulfone (PES) Etc. The.
Among these, polyolefin, polystyrene (PS), acrylic resin (PMMA), polyimide (PI), liquid crystal polymer, polyether ether ketone (PEEK), fluororesin, polybutylene terephthalate (PBT), polycarbonate (PC), cycloolefin Polymer (COP), polyphenylene sulfide (PPS), polyphenylene ether (PPE), and polyphenylene sulfone (PES) are preferable from the viewpoint of water resistance and heat resistance.

(Thermosetting resin)
Examples of the thermosetting resin include 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, Examples thereof include an imide resin, a urethane resin, and a urea resin.
Among these, phenol resin, unsaturated polyester, epoxy resin, vinyl ester resin, allyl ester resin, and 1,2-polybutadiene are preferable, and one or a mixture of two or more may be used.

(Suitable resin)
In fields where airtightness is required, a combination of epoxy resin and phenolic resin, unsaturated polyester, vinyl ester resin, allyl ester resin, 1,2-polybutadiene, etc. have high airtightness without voids in the cured product. Since a body can be obtained, it is preferable.

  Furthermore, in fields where heat resistance, acid resistance, etc. are required, resins having a molecular skeleton such as bisphenol A type, novolac type, cresol novolak type, and resins having an olefinic molecular skeleton such as epoxy resins and phenol resins Vinyl ester resin and 1,2-polybutadiene are preferred.

(Composition ratio)
The composition ratio of the component (A) and the component (B) in the conductive resin composition of the present invention is preferably such that the component A: component B is (20 to 99% by mass): (80 to 1% by mass), More preferably, it is (30-95 mass%) :( 70-5 mass%), More preferably, it is (50-92 mass%) :( 50-8 mass%). When the component (A) is less than 20% by mass, high conductivity cannot be expressed. On the other hand, if it exceeds 99% by mass, the processing becomes difficult, which is not preferable.

(Elastomer component)
The component (B) of the present invention preferably contains an elastomer component in an amount of 0.5 to 80% by mass, more preferably 1 to 80% by mass, and still more preferably 2 to 75% by mass. When the elastomer component is less than 0.5% by mass, a brittle material is obtained. On the other hand, if it exceeds 80% by mass, the rigidity is insufficient and the ribs are crushed when formed into a molded body, such being undesirable.

  The elastomer component is a polymer having rubber-like elasticity near normal temperature, such as acrylonitrile butadiene rubber, hydrogenated nitrile rubber, styrene butadiene rubber, ethylene propylene rubber, ethylene propylene diene terpolymer rubber, ethylene butadiene rubber, Fluoro rubber, isoprene rubber, silicone rubber, acrylic rubber, butadiene rubber, high styrene rubber, chloroprene rubber, urethane rubber, polyether-based special rubber, ethylene tetrafluoride / propylene rubber, epichlorohydrin rubber, norbornene rubber, butyl rubber, styrene Thermoplastic elastomer, olefin thermoplastic elastomer, urethane thermoplastic elastomer, polyester thermoplastic elastomer, polyamide thermoplastic elastomer, 1,2-polybutadiene Thermoplastic elastomer, fluorine-based thermoplastic elastomer, soft acrylic resins. These may be used alone or in combination of two or more.

  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, fluoro thermoplastic elastomers, and soft acrylic resins are preferred.

(Additive)
Furthermore, in the conductive resin composition of the present invention, glass fiber, whisker, metal oxide, organic fiber, for the purpose of improving hardness, strength, conductivity, moldability, durability, weather resistance, water resistance, etc. Additives such as UV stabilizers, antioxidants, mold release agents, lubricants, water repellents, thickeners, low shrinkage agents, hydrophilicity imparting agents and the like may be added.

(Production method of resin composition)
The conductive resin composition of the present invention uses, for example, a mixer or a kneader generally used in the resin field such as a roll, an extruder, a kneader, a Banbury mixer, a Henschel mixer, or a planetary mixer. Can be obtained by mixing uniformly.

  The conductive resin composition of the present invention may be pulverized or granulated for the purpose of facilitating material supply to a molding machine or a mold. 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 pelletizing method using an extruder, a ruder, a kneader or the like, or a bread type granulator may be used.

(Molded body)
There is no particular limitation on the method for forming the conductive resin composition of the present invention into a molded body. Specific examples of the molding method include, but are not limited to, a compression molding method, a transfer molding method, an injection molding method, a casting method, and an injection compression molding method. In these molding processes, it is preferable that the inside of the mold or the entire mold is in a vacuum state. In addition, it is more preferable to provide an apparatus that can adjust the mold temperature up and down because a highly accurate molded body can be obtained.

  In order to obtain a molded body with good thickness accuracy, it is preferable that the sheet is once formed into a sheet having a predetermined thickness and width using an extruder, a roll, a calender or the like, and then rolled again with a roll or a calender. Further, in order to eliminate voids and air in the sheet, it is preferable to perform extrusion molding in a vacuum state.

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

(Physical properties of the molded product)
The molded body of the conductive resin composition of the present invention preferably has a volume resistivity of 0.1 Ωcm or less. More preferably, it is 0.05 ohm-cm or less, More preferably, it is 0.01 ohm-cm or less. If the volume resistivity exceeds 0.1 Ωcm, it may be restricted in a field where high conductivity is required.

The molded product of the conductive resin composition of the present invention preferably has a contact resistance with carbon paper of 0.1 Ωcm ² or less. More preferably, it is 0.05 ohm-cm < ² > or less, More preferably, it is 0.01 ohm-cm < ² > or less. When the contact resistance exceeds 0.1 Ωcm ² , there is a possibility that the field where high conductivity is required is limited.

(Separator for fuel cell)
There is no particular limitation on the method for molding the conductive resin composition of the present invention into a fuel cell separator (hereinafter sometimes referred to as “separator”). For example, compression molding, transfer molding, injection molding, and the like. , Casting method and injection compression molding method. Further, a method in which the inside of the mold or the entire mold is evacuated during the molding process is more preferable.

  In compression molding, it is preferable in terms of productivity to use a multi-cavity mold. More preferably, when a multistage press (lamination press) is used, a large number of products can be formed with a small output. In order to improve the surface accuracy with a flat product, it is preferable that the sheet is once molded and then compression molded as described above.

  In the injection molding, for the purpose of further improving the moldability, a method of injecting carbon dioxide gas from the middle of the molding machine cylinder, dissolving it in the material, and molding in a supercritical state may be adopted. In order to increase the surface accuracy of the product, it is preferable to use an injection compression method. As the injection compression method, a method of injecting and closing with the mold open, a method of injecting while closing the mold, and a method of applying the mold clamping force after injecting with the mold clamping force of the closed mold being zero Etc.

  Although there is no restriction | limiting about the metal mold | die to be used, For example, when solidification of material is quick and fluidity | liquidity is bad, it is preferable to use the heat insulation metal mold | die with which the heat insulation layer was prepared in the cavity. Further, a mold in which a temperature profile system capable of raising and lowering the mold temperature during molding is introduced is more preferable. Examples of the temperature profile method include a system by switching between induction heating and a refrigerant (air, water, oil, etc.), a system by switching between a heat medium (hot water, heating oil, etc.) and a refrigerant, and the like.

  As the mold temperature, an optimum temperature can be selected and searched according to the type of the composition. For example, it can be appropriately determined within a temperature range of 90 to 200 ° C. and a range of 10 to 1200 seconds. When the molded product is taken out at a high temperature, it may be cooled, but the method is not limited. For example, for the purpose of suppressing warpage, a method of cooling a molded product by sandwiching it with a cooling plate, a method of cooling the entire mold, or the like can be mentioned.

(Separator shape, etc.)
The fuel cell separator needs to be formed with a flow path for flowing gas on both sides or one side, but can be formed by the above molding method. The flow path for flowing the gas may be formed by machining the molded body of the conductive resin composition. Alternatively, the gas flow path may be formed by compression molding, stamp molding, or the like using a mold having an inverted shape of the gas flow path.

  There are no particular limitations on the channel cross-sectional shape and the channel shape of the separator of the present invention. For example, the channel cross-sectional shape includes a rectangle, a trapezoid, a triangle, a semicircle, and the like. Examples of the channel shape include a straight type and a meandering type. The width of the channel is preferably 0.1 to 2 mm and the depth is 0.1 to 1.5 mm.

  The thinnest part of the separator of the present invention is preferably 1 mm or less. More preferably, it is 0.8 mm. If it exceeds 1 mm, the voltage drop of the cell increases, which is not preferable.

(Physical properties of separator)
The separator of the present invention preferably has a volume resistivity of 0.1 Ωcm or less. More preferably, it is 0.05 ohm-cm or less, More preferably, it is 0.01 ohm-cm or less. When the volume resistivity exceeds 0.1 Ωcm, it is not preferable because it may be restricted in a field where high conductivity is required.

The separator of the present invention preferably has a contact resistance with carbon paper of 0.1 Ωcm ² or less. More preferably, it is 0.05 ohm-cm < ² > or less, More preferably, it is 0.01 ohm-cm < ² > or less. When the contact resistance exceeds 0.1 Ωcm ² , there is a risk of being restricted in applications where high conductivity is required.

(Use)
Moreover, since the conductive resin composition of the present invention can be easily molded, it is also suitable as a composite material in fields other than the fuel cell separator application. Furthermore, the molded body can reproduce the conductivity and thermal conductivity of graphite as much as possible, and an extremely high performance can be obtained in terms of excellent molding accuracy and the like. Therefore, it is useful in various applications such as various parts such as the electronics field, electrical machinery, machinery, and vehicles, and in particular, current collectors for capacitors or various batteries, electromagnetic wave shielding materials, electrodes, heat sinks, heat dissipation parts, electronic parts, It is promising for semiconductor parts, bearings, PTC elements and brushes.

Examples The present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.
The production methods of the carbonaceous materials used in Examples and Comparative Examples are shown below.
(A) Component: Carbonaceous material <A1>: Boron-containing graphite fine powder (impurity BN-containing 0 wt%)
MC coke manufactured by MC Carbon Co., which is non-acicular coke, was coarsely pulverized to a size of 2 mm to 3 mm or less with a pulverizer (manufactured by Hosokawa Micron Co., Ltd.). The coarsely pulverized product was finely pulverized with a jet mill (IDS2UR, manufactured by Nippon Pneumatic Co., Ltd.). Thereafter, the particle size was adjusted to about 20 μm 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.). Boron carbide (B ₄ C) 0.15 kg was added to 14.85 kg of the finely pulverized coke obtained and mixed at 800 rpm with a Henschel mixer for 5 minutes. 1 kg of this was sealed in a graphite crucible with a lid of 1.5 liters, placed in a graphitization furnace using a graphite heater, the inside of the furnace was evacuated and replaced with argon gas, an internal pressure of 0.12 MPa, an argon gas atmosphere Graphitized at a temperature of 2800 ° C. After allowing this to cool in an argon gas atmosphere, the powder was taken out to obtain 0.94 kg of powder. The average particle size of the obtained graphite fine powder was 20 μm, and no nitrogen content was detected.

<A2>: Mixture of vapor grown carbon fiber (hereinafter abbreviated as “VGCF”, Showa Denko Trademark) and A1 (graphite fine powder) 14.1 kg of finely ground coke of A1 above, 0.75 kg of VGCF and boron carbide (B ₄ C) 0.15 kg was added and mixed with a Henschel mixer at 800 rpm for 5 minutes. 1 kg of this was sealed in a graphite crucible with a lid of 1.5 liters, placed in a graphitization furnace using a graphite heater, the inside of the furnace was evacuated and replaced with argon gas, an internal pressure of 0.12 MPa, an argon gas atmosphere Graphitized at a temperature of 2800 ° C. After allowing this to cool in an argon gas atmosphere, the powder was taken out to obtain 0.94 kg of powder. The obtained graphite fine powder had an average particle size of 15 μm, and no nitrogen content was detected.

<A3>: A mixture of carbon nanotubes (hereinafter abbreviated as “CNT”) and A1 (graphite fine powder) 14.1 kg of finely pulverized coke of A1 above, 0.75 kg of CNT obtained by the following method (the production method is as follows) Described) and boron carbide (B ₄ C) 0.15 kg were added and mixed with a Henschel mixer at 800 rpm for 5 minutes. 1 kg of this was sealed in a graphite crucible with a lid of 1.5 liters, placed in a graphitization furnace using a graphite heater, the inside of the furnace was evacuated and replaced with argon gas, an internal pressure of 0.12 MPa, an argon gas atmosphere Graphitized at a temperature of 2800 ° C. After allowing this to cool in an argon gas atmosphere, the powder was taken out to obtain 0.94 kg of powder. The average particle size of the obtained graphite fine powder was 12 μm, and no nitrogen content was detected.

<Manufacturing method of CNT>
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 to 10 nm and a fiber length of 0.05 to 5 μm.

<A4>: Boron-containing graphite fine powder (BN content 0.7% by mass)
1 kg of boron carbide (B ₄ C) was added to 14 kg of the finely pulverized coke of A1 and mixed with a Henschel mixer at 800 rpm for 5 minutes. 1 kg of this was enclosed in a graphite crucible with a lid having a volume of 1.5 liters, placed in a graphitization furnace using a graphite heater, and graphitized at a temperature of 2800 ° C. in an argon gas atmosphere with an internal pressure of 0.103 MPa. . This was replaced with a nitrogen atmosphere and allowed to cool, and then the powder was taken out to obtain 0.92 kg of powder. The obtained graphite fine powder had an average particle diameter of 18 μm, and as a result of analyzing the nitrogen content, it was detected to be 0.39% by mass and contained in an amount of about 0.7% by mass when converted to BN.

<A5>: Boron-free graphite fine powder 15 kg of the finely pulverized coke of A1 above was mixed with a Henschel mixer at 800 rpm for 5 minutes. 1 kg of this was sealed in a graphite crucible with a lid of 1.5 liters, placed in a graphitization furnace using a graphite heater, and graphitized at a temperature of 2800 ° C. under an air flow of an internal pressure of 0.103 MPa and an argon gas atmosphere. After allowing this to cool in a nitrogen atmosphere, the powder was taken out to obtain 0.96 kg of powder. The obtained graphite fine powder had an average particle size of 21 μm and was not detected as a result of analyzing the nitrogen content.

<A6>: Mixture of vapor grown carbon fiber (hereinafter abbreviated as “VGCF”, registered trademark of Showa Denko) and A1 (graphite fine powder) (BN content 0.6 wt%)
VGCF 0.75 kg and boron carbide (B ₄ C) 0.15 kg were added to 14.1 kg of the finely pulverized coke of A1 and mixed for 5 minutes at 800 rpm with a Henschel mixer. 1 kg of this was enclosed in a graphite crucible with a lid having a volume of 1.5 liters, placed in a graphitization furnace using a graphite heater, and graphitized at a temperature of 2800 ° C. in an argon gas atmosphere with an internal pressure of 0.103 MPa. . After allowing this to cool in a nitrogen atmosphere, the powder was taken out to obtain 0.94 kg of powder. The obtained graphite fine powder had an average particle size of 14 μm. As a result of analyzing the nitrogen content, it was detected to be 0.32% by mass, and when converted to BN, it contained about 0.58% by mass.
Table 1 shows various characteristics of the carbonaceous material.

A method for measuring various characteristics of the carbonaceous material is shown below.
<Average particle size>
Weigh 50 mg of sample (carbonaceous material), add it to 50 ml of distilled water, add 0.2 ml of 2% Triton (surfactant) aqueous solution, and ultrasonically disperse for 3 minutes, then Microtrack made by Nikkiso Co., Ltd. Measured with an HRA instrument.

<Nitrogen content>
In accordance with JIS M8813 (semi-micro gasification method), 0.1 g of sample (carbonaceous material) is weighed into a tin capsule, heated and decomposed in a steam stream, and the generated ammonia is collected in a boric acid saturated solution. After that, this was titrated with a sulfuric acid standard solution, and the mass percentage with respect to the anhydrous sample was determined to determine nitrogen.

<Sulfur content>
In accordance with JIS M8813 (high temperature combustion method), 0.1 g of sample (carbonaceous material) is weighed in a quartz boat, heated to about 1350 ° C. in an oxygen stream, oxidized sulfur and gasified, and this is peroxidized After collecting in hydrogen water, sulfate ions were measured by anion chromatography and converted to the sulfur concentration in the sample.

<Boron content>
Weigh 50 mg of the sample into a digester container, add sulfuric acid and nitric acid, decompose by microwave heating (230 ° C) (digester method), add perchloric acid (HClO ₄ ) and decompose with water. After dilution, this was applied to an ICP emission spectrometer to measure the amount of boron.

<BN content>
The equivalent amount of BN was calculated from the molar ratio of the total amount of nitrogen measured by the semi-micro gasification method and the total amount of boron measured by the ICP emission analyzer.

<Hot water extraction water conductivity>
Using a pressure decomposition vessel (AD-70, manufactured by Yanaco), weigh 45 g (2 μS / cm or less) of pure water and 9 g of a sample (carbonaceous material) up to ± 0.05 g, and seal 150 ± 0.00. Place in an oven calibrated to 5 ° C. and extract for 120 hours. Then, it cooled to room temperature (23 degreeC), filtered, and the extracted water was measured with the conductivity meter (ES-12) made from HORIBA.

<Powder consolidation specific resistance>
The powder compaction specific resistance in the pressing direction is measured using the apparatus shown in FIG. Reference numerals 1 and 1 ′ denote voltage measuring terminals, which are installed at the center of the side wall as shown in FIG. 2 is a sample. 3 is a side frame and 4 is a compression rod, which are all made of insulating resin. 5 and 5 'are copper electrodes, 6 is a voltmeter, and 7 is a constant current generating power source. Using the four-terminal method shown in FIG. 1, the specific resistance of the sample is measured as follows.
The sample is compressed by the compression rod 4 and pressurized to 1 MPa. A constant current (I) 1A is passed from the electrode 5 to the electrode 5 '(in the pressurizing direction). The voltage (V) between the terminals is measured by the terminals 1 and 1 ′. If the electric resistance (between terminals) of the sample is R ₂ (Ω), then R ₂ = V ₂ / I ₂ . From this, the specific resistance can be obtained by ρ ₂ = R ₂ × S ₂ / L ₂ (ρ ₂ : specific resistance, S ₂ = cross-sectional area perpendicular to the energization direction of the sample, that is, the pressurizing direction (cm ² ), L ₂ is the distance (cm) between the terminals 1, 1 ′). In the actual measurement, the sample was filled with a sample such that the bottom surface was a 3 cm × 3 cm square and the height was 3 to 4 cm in a pressurized state of 1 MPa.

Examples 1-3, Comparative Examples 1-3
The raw materials were kneaded at a temperature of 80 ° C. and 35 rpm for 5 minutes using a lab plast mill (manufactured by Toyo Seiki Seisakusho, Model 50C150) at the respective components and composition ratios shown in Table 2 below. The kneaded product is put into a mold capable of forming a flat plate of 100 mm × 100 mm × 2 mm, cured using a 50 t compression molding machine at a temperature of 180 ° C. and a pressure of 15 MPa for 10 minutes, and then a temperature of 40 ° C. and a pressure using a cooling press. The molded body was obtained by cooling for 2 minutes under the condition of 15 MPa. Table 3 shows the characteristics of the obtained molded body.

  From Table 3, a carbonaceous material containing boron, having a low content of nitrogen and sulfur, and having almost no BN provides a molded product having high conductivity, excellent bending characteristics, and little extraction of ionic impurities with hot water. . On the other hand, when boron-containing carbonaceous materials are used as in Comparative Examples 1 and 3, the conductivity of the hot water extraction water is high and the bending characteristics are also deteriorated. Moreover, when boron is not included like the comparative example 2, electroconductivity will worsen.

Example 4 and Comparative Example 4
The raw materials of each component and blending ratio shown in Table 4 were kneaded for 5 minutes at a temperature of 90 ° C. and 35 rpm using a lab plast mill (manufactured by Toyo Seiki Seisakusho, Model 50C150). The kneaded product was put into a mold capable of forming a flat plate of 100 mm × 100 mm × 2 mm, and cured for 10 minutes at a temperature of 180 ° C. and a pressure of 15 MPa using a 50 t compression molding machine. Then, it cooled for 2 minutes on the conditions of the temperature of 40 degreeC, and the pressure of 15 MPa using the cooling press. Further, in order to accelerate curing, the molded body was obtained by after-curing for 3 hours in an oven of 300 ° C. and nitrogen atmosphere. Table 5 shows the characteristics of the obtained molded body.

  From Table 5, a carbonaceous material containing boron, having a low content of nitrogen and sulfur, and having almost no BN provides a molded body having high conductivity, excellent bending characteristics, and almost no extraction of ionic impurities with hot water. . On the other hand, when a carbonaceous material containing boron but containing many impurities is used, the conductivity of hot water extraction water is high, and the bending characteristics are poor.

Examples 5-8, Comparative Examples 5-9
The raw materials of each component and composition ratio shown in Table 6 were kneaded for 5 minutes at a temperature of 200 ° C. and 35 rpm using a lab plast mill (manufactured by Toyo Seiki Seisakusho, Model 50C150). The kneaded product was put into a mold capable of forming a flat plate of 100 mm × 100 mm × 2 mm, and preheated at a temperature of 230 ° C. for 3 minutes and then heated and pressurized at a pressure of 15 MPa for 2 minutes using a 50 t compression molding machine. Next, it was held for 5 minutes at a temperature of 135 ° C. under a pressure of 15 MPa, and cooled for 2 minutes under the conditions of a temperature of 60 ° C. and a pressure of 15 MPa using a cooling press to obtain a molded body. Table 7 shows the characteristics of the obtained molded body.

  From Table 7, a carbonaceous material containing boron, having a low content of nitrogen and sulfur, and having almost no BN provides a molded product having high conductivity, excellent bending properties, and little extraction of ionic impurities with hot water. . On the other hand, boron is contained as in Comparative Example 5 and Comparative Examples 7 to 9, but when a carbonaceous material with a large amount of impurities is used, the conductivity of hot water extraction water is high and bending characteristics are poor. Moreover, when boron is not included like the comparative example 6, electroconductivity will worsen.

Examples 9-10, Comparative Examples 10-11
The raw materials of each component and composition ratio shown in Table 8 were kneaded for 5 minutes at a temperature of 200 ° C. and 35 rpm using a lab plast mill (manufactured by Toyo Seiki Seisakusho, Model 50C150). The kneaded product was put into a mold capable of forming a flat plate of 100 mm × 100 mm × 2 mm, and preheated at a temperature of 220 ° C. for 3 minutes and then heated and pressurized at a pressure of 15 MPa for 2 minutes using a 50 t compression molding machine. Next, it was held for 5 minutes at a temperature of 140 ° C. under a pressure of 15 MPa, and cooled for 2 minutes under the conditions of a temperature of 40 ° C. and a pressure of 15 MPa using a cooling press to obtain a molded body. Table 9 shows the characteristics of the obtained molded body.

  From Table 9, a carbonaceous material containing boron, low in nitrogen and sulfur, and almost free from BN can provide a molded body having high conductivity, excellent bending characteristics, and little extraction of ionic impurities with hot water. . On the other hand, when a carbonaceous material containing boron but containing many impurities is used, the conductivity of hot water extraction water is high, and the bending characteristics are poor.

Example 11 and Comparative Example 12
The raw materials of each component and composition ratio shown in Table 10 were kneaded for 5 minutes at a temperature of 300 ° C. and 35 rpm using a lab plast mill (manufactured by Toyo Seiki Seisakusho, Model 50C150). The kneaded material was put into a mold capable of forming a flat plate of 100 mm × 100 mm × 2 mm, and preheated at a temperature of 320 ° C. for 3 minutes and then heated and pressurized at a pressure of 15 MPa for 2 minutes using a 50 t compression molding machine. Next, it was held at a temperature of 265 ° C. for 5 minutes under a pressure of 15 MPa, and cooled for 2 minutes under the conditions of a temperature of 40 ° C. and a pressure of 15 MPa using a cooling press to obtain a molded body. Table 11 shows the properties of the obtained molded body.

  From Table 11, a carbonaceous material containing boron, having a low content of nitrogen and sulfur, and having almost no BN, has a high conductivity, excellent bending characteristics, and a molded product with little extraction of ionic impurities by hot water. . On the other hand, when a carbonaceous material containing boron but containing many impurities is used, the conductivity of hot water extraction water is high, and the bending characteristics are poor.

A method for measuring the characteristics of the molded body is shown below.
<Volume specific resistance>
Based on JIS K7194, it measured by the four probe method.
<Contact resistance>
The contact resistance value (Rc) with carbon paper (TGP-H-060 manufactured by Toray Industries, Inc.) was measured 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. The contact resistance value between the carbon paper and the test piece is calculated from the above three resistance values by the following formula.
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

<Bending strength, flexural modulus and bending strain>
Using an autograph (AG-10kNI) manufactured by Shimadzu Corporation, a JIS K6911 method, a test piece (80 mm × 10 mm × 1.5 mm) with a span interval of 64 mm and a bending speed of 1 mm / min is a three-point system. It was measured by a bending strength measurement method.

Example 12
The composition of Example 1 was put into a mold capable of forming a flat plate having a size of 200 mm × 120 mm × 1.5 mm, a groove width of 1 mm, a groove depth of 0.5 mm on both sides, and a 380 t compression molding machine. Then, pressurization and heating were performed for 10 minutes under a mold temperature of 180 ° C. and a pressure of 50 MPa to obtain a separator plate for fuel cells. The obtained flat plate is grooved on both sides, has a volume resistivity of 5.6 mΩcm, a contact resistance of 3.1 mΩcm ² , a thermal conductivity of 19 W / m · K, and an air permeability of 2.3 × 10 ⁻⁹ cm ² / sec. Met.

Example 13
The composition of Example 5 was put into a mold capable of forming a flat plate having 200 mm × 120 mm × 1.5 mm groove width 1 mm pitch and groove depth 0.5 mm on both sides, and a 380 t compression molding machine was used. And then pressurizing and heating at a mold temperature of 230 ° C. under a pressure of 50 MPa for 3 minutes, then lowering the temperature to 135 ° C. and holding for 5 minutes, and then lowering the temperature to 60 ° C. to form a separator-shaped molded body for fuel cells Got. The obtained molded body has a groove on both sides, a volume resistivity of 4.2 mΩcm, a contact resistance of 2.8 mΩcm ² , a thermal conductivity of 21 W / m · K, and an air permeability of 4.6 × 10 ⁻⁹ cm ² / sec. Met.

A method for measuring the characteristics of the flat plate is shown below.
<Thermal conductivity>
Using a laser flash method (t _1/2 method, laser flash method thermal constant measuring device LF / TCM FA8510B, manufactured by Rigaku Denki Co., Ltd.), a test piece (diameter φ10 mm, thickness 1.7 mm) was irradiated at 80 ° C. in vacuum. The measurement was performed under the condition of ruby laser light (excitation voltage: 2.5 kV).
<Air permeability>
Based on JIS K7126 A method, it measured using helium gas at 23 degreeC.

It is a schematic cross section which shows the measuring method of powder compaction specific resistance (pressurization direction). It is a schematic cross section which shows the measuring method of contact resistance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1 'Voltage measuring terminal 2 Sample 3 Side frame 4 Compression rod 5, 5' Copper electrode 6 Voltmeter 7 Constant current generating power source 8 Carbon paper 9 Test piece 10 Gold-plated brass 11 Constant current generator 12 Voltmeter

Claims (9)

(A) nitrogen content is 0.2 wt% or less, and the sulfur content is 20 to 99 mass% boron-containing carbonaceous material is less than 0.05 wt% and (B) including guiding the 1:80 mass% resin binder A fuel cell separator formed by molding an electrically conductive resin composition. (A) Boron in a boron containing carbonaceous material is 0.01-5 mass%, The fuel cell separator of Claim 1 characterized by the above-mentioned. (A) Boron nitride (BN) in a boron containing carbonaceous material is 0.5 mass% or less, The fuel cell separator of Claim 1 or 2 characterized by the above-mentioned. (A) Conductivity of water extracted by hot water under a condition of a mass ratio of pure water 5 to boron-containing carbonaceous material 1 at a temperature of 150 ° C. for 120 hours is 150 μS / cm or less. The fuel cell separator according to any one of 1 to 3 . (A) a boron-containing carbonaceous material, any one of the claims 1-4 in which the powder compaction ratio of pressure direction resistance in a state where pressurized to 1MPa is characterized by having a property or less 0.05Ωcm The separator for a fuel cell according to Item. (A) The raw material of the boron-containing carbonaceous material is coke, mesophase carbon, pitch, charcoal, resin charcoal, natural graphite, artificial graphite, expanded graphite, carbon black, carbon fiber, vapor grown carbon fiber, carbon nanotube, amorphous carbon The fuel cell separator according to any one of claims 1 to 5 , wherein the separator is one or a combination of two or more selected from the group consisting of fullerenes. (B) Resin binder contains 0.5-80 mass% of elastomer components, The fuel cell separator of any one of Claims 1-6 characterized by the above-mentioned. The fuel cell separator according to any one of claims 1 to 7, characterized in that volume resistivity of 0.1? Cm or less and a contact resistance of 0.1? Cm ² or less. One or both sides to a width 0.1 to 2 mm, groove depth 0.1~1.5mm is formed, any of the preceding claims in which the thickness of the thinnest portion is characterized in that it is a below 1mm or less the fuel cell separator according to any one of claims.

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