JP4647950B2 - Carbon / phenol resin composite molding material manufacturing method and fuel cell separator - Google Patents

Description

The present invention is a manufacturing method and, a fuel cell separator obtained by molding the carbon-phenol resin composite molded material of carbon phenolic resin composite molding material used for such molding of the separator of the fuel cell of the solid polymer electrolyte membrane type It is about.

  2. Description of the Related Art Conventionally, various types of parts formed of resin molded products have been provided as parts for electric / electronic devices and as separators used in solid polymer electrolyte fuel cells. These molded products are often required to have high electrical conductivity, high heat dissipation, and high strength, and as resin molded products that require such properties of electrical conductivity, thermal conductivity, and high strength, 2. Description of the Related Art Conventionally, a composite molding material made of carbon powder and phenol resin is known.

  As a composite molding material comprising this carbon powder and a phenol resin, it is common to use a granulated material obtained by mixing a phenol resin and a carbon powder and granulating it. Such granular carbon / phenolic resin composite molding materials have been conventionally produced as follows. First, phenols and aldehydes are reacted in the presence of a reaction catalyst to prepare a phenol resin, which is dehydrated. Next, the phenol resin is diluted as it is or by adding a solvent, and this is added to carbon powder and kneaded with a kneader or the like. The kneaded product is extruded and dried, and then pulverized. A carbon / phenolic resin composite molding material that is a mixed particle with a phenolic resin can be obtained. Parts such as electric and electronic devices can be molded.

  Here, the granular carbon / phenolic resin composite molding material obtained as described above generally contains about 30 to 40% by mass of a phenolic resin. This is because the phenol resin and the carbon powder are poorly dispersible, and if the amount of the phenol resin is small, the surface of the carbon powder cannot be sufficiently covered with the phenol resin, and the molded product is obtained by uniformly dispersing the carbon powder. Therefore, the amount of the phenol resin is as much as about 30 to 40% by mass.

  However, by increasing the amount of the phenol resin in this way, it is possible to ensure the strength such as the bending strength of the molded product, but as the amount of the phenol resin increases, the amount of the carbon powder relatively decreases. However, there is a problem that the electrical conductivity and thermal conductivity of the molded product are lowered, and the performance as a part for an electric / electronic device is deteriorated.

As a separator used in a solid polymer electrolyte fuel cell, a composite molding material made of carbon powder and a phenol resin has been proposed. However, a separator for a fuel cell is gas impermeable and It is required to have high conductivity. (For example, refer patent documents 1-3 etc.).
JP 2000-348740 A Japanese Patent Application Laid-Open No. 2001-250566 JP 2002-25571 A

  Since separators for fuel cells are required to have particularly high conductivity in this way, a carbon / phenol resin composite molding material is prepared by blending 75% by mass or more of carbon powder. However, when the amount of carbon powder is increased in this way, the amount of phenol resin is decreased, and the gas impermeability and flexibility of the separator obtained by molding the carbon / phenol resin composite molding material are lowered. . In other words, if the amount of carbon powder increases and the amount of phenol resin decreases accordingly, the flowability of the carbon-phenol resin composite molding material is insufficient, and voids between the carbon powders are formed when the separator is molded. The resin cannot be sufficiently filled with the phenol resin, and as a result, the gas impermeability and flexibility of the separator are lowered.

  Therefore, in order to fill the voids in the carbon powder with phenol resin, molding is performed by applying high pressure. However, the separator obtained by such high-pressure molding partially has uneven thickness and distortion. It is likely to occur. In a fuel cell, dozens to hundreds of separators are stacked and incorporated. However, if the separator has low flexibility as described above, and if the separator has uneven thickness or distortion, a large number of separators are used to assemble the fuel cell. When the separators are stacked and tightened, cracks occur, and cracks and the like easily occur due to vibration, impact, and expansion / contraction due to temperature changes during use of the fuel cell.

The present invention has been made in view of the above points, and is a carbon / phenolic resin composite molding capable of obtaining a fuel cell separator having high conductivity, thermal conductivity, gas impermeability and high flexibility. An object of the present invention is to provide a method for producing a material, and to provide a fuel cell separator having high conductivity, thermal conductivity, gas impermeability and high flexibility. It is.

A method for producing a carbon / phenolic resin composite molding material for molding a fuel cell separator according to claim 1 of the present invention comprises mixing phenols, aldehydes and rubbers with carbon powder in the presence of a reaction catalyst. in by the polymerization reaction, a manufacturing method of a carbon-phenol resin composite molding material for producing a composite molded material of rubber modified phenolic resin and carbon, the content of carbon powder in the composite molding material 75 The phenolic resin modified with rubber is characterized by having a rubber modification rate of 5 to 90% by mass .

According to the present invention, a carbon-phenol resin having a high carbon content of 75% by mass or more is obtained by polymerizing a phenol, an aldehyde, and a rubber in the presence of a reaction catalyst while mixing with a carbon powder. The composite molding material can be obtained with good dispersibility between the rubber-modified phenolic resin and the carbon powder, and a molded product in which the carbon powder is uniformly dispersed can be molded. It is possible to obtain a molded product having high performance such as property, thermal conductivity and gas impermeability. In addition, the phenolic resin modified with rubber in the carbon / phenolic resin composite molding material has improved flexibility due to the modification by the rubber, and the molded product obtained by molding this carbon / phenolic resin composite molding material can be used. Flexibility can be improved, and the occurrence of cracks and cracks in the molded product can be reduced. Further, the phenol modification resin modified with rubber has a rubber modification rate of 5 to 90% by mass, so that the flexibility of the molded product can be improved without greatly reducing the bending strength and the bending elastic modulus. is there.

  The invention of claim 2 is characterized in that, in claim 1, acrylonitrile butadiene rubber is used as the rubber.

  According to this invention, acrylonitrile butadiene rubber can easily undergo an addition reaction with an initial condensate of phenols and aldehydes, and can introduce rubber into the skeleton of the phenolic resin. It is possible to obtain a high effect of improvement.

The fuel cell separator according to claim 3, the carbon phenolic resin composite molded carbon phenolic resin composite molded material produced by the production method of the material according to claim 1 or 2, with a predetermined flow path pattern It is characterized by being formed into a thin plate-like molded body.

  According to this invention, it is possible to obtain a fuel cell separator having high conductivity and gas impermeability in a state where carbon powder is uniformly dispersed at a high content of 75% by mass or more, and The phenolic resin modified with rubber in the carbon / phenolic resin composite molding material has improved flexibility due to rubber modification, and can reduce the occurrence of cracks and cracks in the fuel cell separator. Is.

The invention according to claim 4 is characterized in that, in claim 3 , the rubber-modified phenol resin in the carbon-phenol resin composite molding material has a nitrogen component content of 0.3% by mass or less extracted into methanol. It is what.

  According to this invention, it is possible to obtain a fuel cell separator in which adverse effects due to nitrogen components are eliminated.

According to a fifth aspect of the present invention, in the third or fourth aspect , a test piece having a length of 100 mm, a width of 13 mm, and a thickness of 7 mm is attached to a fulcrum distance of 80 mm in accordance with JIS K 7171 “Plastic-Bending Properties Test Method” The maximum amount of deflection at the time of break when tested in (5) is 0.5 mm or more.

  According to this invention, it has a sufficiently high flexibility to prevent the occurrence of cracks and cracks, and reliably reduces the occurrence of cracks and cracks in the fuel cell separator. It is something that can be done.

  According to the present invention, a carbon-phenol resin having a high carbon content of 75% by mass or more is obtained by polymerizing a phenol, an aldehyde, and a rubber in the presence of a reaction catalyst while mixing with a carbon powder. The composite molding material can be obtained with good dispersibility between the rubber-modified phenol resin and the carbon powder, and a molded product in which the carbon powder is uniformly dispersed can be molded. Accordingly, it is possible to obtain a fuel cell separator having high performance such as conductivity, thermal conductivity, and gas impermeability.

  Moreover, the phenolic resin modified with rubber in the carbon / phenolic resin composite molding material has improved flexibility due to the modification by rubber, and the molded product obtained by molding this carbon / phenolic resin composite molding material Flexibility can be improved. Therefore, it is possible to obtain a fuel cell separator with reduced occurrence of cracks and cracks.

  Hereinafter, the best mode for carrying out the present invention will be described.

  In the present invention, as phenols, phenol derivatives can be used in addition to phenol. Examples of the phenol derivative include trifunctional compounds such as m-cresol, resorcinol, and 3,5-xylenol, tetrafunctional compounds such as bisphenol A, bisphenol S, and dihydroxydiphenylmethane, o-cresol, p-cresol, and p- Bifunctional o- or p-substituted phenols such as ter-butylphenol, p-phenylphenol, p-cumylphenol, p-nonylphenol, 2,4- or 2,6-xylenol can be exemplified. Furthermore, halogenated phenols substituted with chlorine or bromine can also be used. As phenols, one type can be selected and used, or a plurality of types can be mixed and used.

  In the present invention, the formalin which is a formaldehyde aqueous solution is most suitable as the aldehyde, but a form such as paraformaldehyde, acetaldehyde, benzaldehyde, trioxane and tetraoxane can be used, and a part of other aldehydes. Alternatively, it is also possible to use a material in which most of the furfural or furfuryl alcohol is replaced.

  Furthermore, the rubbers in the present invention are not particularly limited, but natural rubber, fluorine rubber, silicone rubber, butyl rubber, chloroprene rubber, nitrile chloroprene rubber, chlorinated butyl rubber, chlorinated polyethylene, epichlorohydrin rubber, epichlorohydrin / ethylene. Examples thereof include oxide rubber, urethane rubber, acrylic rubber, ethylene / propylene rubber, butadiene rubber, acrylonitrile / butadiene rubber (NBR), styrene / butadiene rubber, and the like. These can be used singly or in combination. .

  Rubbers can be used in the form of a solid powder at room temperature (in the range of 0 to 40 ° C.), or can be used in liquid form such as latex produced by emulsion polymerization and dispersed in water. Solid and liquid can also be used in combination.

  Further, as the carbon powder in the present invention, any carbonaceous powder can be used without any particular limitation. For example, natural graphite, artificial graphite, quiche graphite, expanded graphite, carbon black, mesophase Carbon, coke powder, charcoal powder, rice husk charcoal, carbon fiber powder, or the like can be used, and spheroidized graphite or agglomerated graphite obtained by processing these can be used. Carbon nanotubes can also be used. The carbon powder can be used by selecting one type from these, or by mixing a plurality of types. The particle size of the carbon powder is not particularly limited, but is preferably about 0.1 to 200 μm.

  Then, the above phenols, aldehydes, rubbers, and reaction catalyst are placed in a reaction vessel such as a reaction kettle, and carbon powder and other components added as necessary are added to the reaction vessel. In the presence, phenols, aldehydes and rubbers are polymerized. Components added as necessary include lubricants, fibers, epoxy resins, coupling agents, vulcanizing agents, vulcanization accelerators, and the like.

  The above reaction catalyst is mainly for reacting phenols with aldehydes. Alkali metal oxides such as sodium, potassium and lithium, hydroxides, carbonates, or alkaline earths such as calcium, magnesium and barium Examples thereof include metal oxides, hydroxides, carbonates, and tertiary amine compounds. Among these, one can be used alone, or two or more can be used in combination. Specific examples include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, calcium hydroxide, magnesium hydroxide, barium hydroxide, calcium carbonate, magnesium oxide, calcium oxide, trimethylamine, triethylamine, triethanolamine, 1,8-diazabicyclo [5,4,0] undecene-7.

  The above reaction is carried out with stirring in an amount of water sufficient to stir the reaction system. At the beginning of the reaction, the reaction system is in the form of a viscous mayonnaise and flows with stirring. As the reaction proceeds, the condensation reaction product of phenols, aldehydes and rubbers containing carbon powder begins to separate from the water in the system, and the phenol resin and carbon powder modified with the rubber produced by the reaction The agglomerated composite particles are suddenly dispersed throughout the reaction vessel. Further, when the reaction of the rubber-modified phenol resin is further promoted to a desired level and the mixture is cooled and then stirred, the composite particles are precipitated and separated from water. This composite particle is a fine water-containing granule, which can be easily separated from water by taking out from the reaction vessel and filtering, and drying it to make it suitable for molding be able to.

  Here, the blending amount of the aldehyde with respect to the phenol is preferably in the range of 1.0 to 3.0 mol of the aldehyde with respect to 1 mol of the phenol. Moreover, although the compounding quantity of a reaction catalyst changes greatly with the kind of reaction catalyst, the range of 0.05-10 mass% with respect to phenols is preferable.

  The rubbers may be charged into the reaction vessel from the beginning of the reaction as described above, but may be charged from the middle of the reaction, or may be charged at the end of the reaction. In either case, rubber reacts with an initial condensation reaction product of phenols and aldehydes, and a phenol resin modified with rubber can be obtained. For example, when NBR is used as a rubber, as shown in the following chemical reaction formula, NBR easily causes an addition reaction with an initial adduct of phenols and aldehydes, and the phenol resin is easily modified with NBR. It is something that can be done. In this rubber-modified phenol resin, it is preferable to set the addition amount of rubbers so that the rubber modification rate is in the range of 5 to 90% by mass, and more preferably in the range of 5 to 70% by mass. When the rubber modification rate of the rubber-modified phenolic resin is less than 5% by mass, it is difficult to sufficiently obtain the effect of improving the flexibility of the cured resin and improving the flexibility of the molded product by the rubber modification. Conversely, when the rubber modification rate of the rubber-modified phenolic resin exceeds 70% by mass, particularly when it exceeds 90% by mass, the cured resin becomes too soft, and the bending strength and bending elastic modulus of the molded product decrease. Absent. Here, the rubber modification rate of the rubber-modified phenol resin refers to the content ratio of the rubber component in the rubber-modified phenol resin.

  The granule obtained as described above is a carbon / phenolic resin composite molding material containing carbon powder, and the carbon powder and rubber-modified phenolic resin are aggregated. The ratio of the modified phenolic resin is the same, and the rubber-modified phenolic resin, which is the binder, is coated very thinly and evenly on the surface of the particles. It can be obtained. Accordingly, it is possible to easily obtain a carbon / phenol resin composite molding material in which the content of the rubber-modified phenol resin as a binder is small and the content of the carbon powder is large and the carbon powder and the rubber-modified phenol resin are uniformly dispersed. It can be done.

  Here, in the present invention, the carbon / phenol resin molding material is prepared such that the content of the carbon powder is 75% by mass or more. The higher the carbon powder content, the higher the electrical conductivity and thermal conductivity of the molded product obtained by molding the carbon / phenolic resin composite molding material. It is necessary that the content of carbon powder in the carbon / phenolic resin composite molding material is 75% by mass or more. However, if the carbon powder content is extremely high, the content of the rubber-modified phenol resin, which is a binder, will be extremely low, and the strength of the molded product obtained by molding may not be secured. The content of the carbon powder in the resin composite molding material is preferably less than 97% by mass.

  In addition, in the carbon-phenol resin composite molding material obtained as described above, as a reaction catalyst for addition condensation reaction of phenols and aldehydes, as described above, oxides or hydroxides of alkali metals or alkaline earth metals By using carbonates or tertiary amines, the rubber-modified phenolic resin can be prevented from containing nitrogen components resulting from the reaction catalyst. Incorporation of the nitrogen component into the molded product obtained in this way can be minimized. The tertiary amine contains a nitrogen component, but since the tertiary amine is not added to the phenol resin, the nitrogen component is not taken into the molecule of the phenol resin, and most of it is transferred to the filtrate and removed. . If a large amount of nitrogen component is taken into a molded product for electric / electronic equipment, the elution of the nitrogen component may cause problems such as corrosion in the electric / electronic equipment. In particular, when a large amount of nitrogen component is taken into the fuel cell separator, it is eluted as ammonia or the like by water generated during operation of the fuel cell, and the output may decrease. Therefore, the smaller the amount of nitrogen component contained in the rubber-modified phenolic resin of the carbon / phenolic resin molding material, the better. The nitrogen component content is ideally 0%, but the nitrogen content is 0.3 mass. It is desirable to substantially prevent the occurrence of problems due to nitrogen components by limiting to less than or equal to%. Here, in the present invention, the nitrogen content in the rubber-modified phenolic resin is determined by adding the methanol to the carbon / phenolic resin molding material to extract the dissolved nitrogen component, and distilling off the methanol to extract the nitrogen content extracted by the Kjeldahl method. It is measured and converted to what mass% of the measured nitrogen amount in the rubber-modified phenol resin. Therefore, even if a rubber-modified phenol resin is prepared using a rubber component containing nitrogen such as NBR, the nitrogen in NBR is not extracted into methanol, so the nitrogen in NBR contains nitrogen in the rubber-modified phenol resin. Not included in the quantity.

  Then, by molding the carbon / phenolic resin composite molding material obtained as described above, it is possible to manufacture parts for electric / electronic devices and separators used for solid polymer electrolyte fuel cells. It is. Molding can be performed by filling a mold with a carbon / phenolic resin composite molding material, and heating and pressing. The heating at this time is preferably performed with the mold temperature set in the range of 130 to 250 ° C., and the pressing is preferably performed at a surface pressure in the range of 10 to 200 MPa.

  Further, the molding may be performed in two steps in addition to the one step. When molding is performed in two stages, first, a carbon / phenolic resin composite molding material is preformed. Preliminary molding is to form a shape that approximates the final shape of a molded product. Since preforming is performed in a shape that approximates the final shape, pressurization may be performed at a low surface pressure in the range of 5 to 25 MPa. Further, heating is not required and it may be performed at room temperature. Even if heating is performed, it is necessary to set the temperature to 100 ° C. or lower. Next, the preformed body obtained by preforming in this way is set in a heated mold and pressed to form a final shape. The heating in the final molding is performed by setting the mold at a temperature of 130 to 250 ° C., and the preform can be completely cured by this heating. Further, the pressing is performed at a surface pressure of 10 to 200 MPa, more preferably 25 to 200 MPa, and by this pressing, the final shape of the molded product can be formed. As described above, even if the carbon / phenolic resin composite molding material has a low flowability, as in the case of using a carbon / phenolic resin composite molding material with a high carbon powder content and a low rubber-modified phenolic resin content. After molding into a rough shape by preliminary molding, molding material can be distributed to every corner in the mold by molding at high pressure in the final molding, and molding with a uniform filling in the mold It can be done.

  FIG. 1 shows a fuel cell separator 4, which is an example of a molded product obtained by the above molding, and is formed by providing gas flow paths 5, 6 formed in a predetermined flow path pattern on one side. It is. An anode 2 and a cathode 3 formed of carbon cloth or carbon paper are disposed on both surfaces of the electrolyte membrane 1 formed as an ion exchange membrane with a fluorine-based resin or the like, and separators are disposed outside the anode 2 and the cathode 3, respectively. 4 can form a cell of a solid polymer electrolyte type fuel cell. A fuel gas containing hydrogen is introduced into the gas flow path 5 between the anode 2 and the separator 4, and the cathode 3. Air is supplied to the gas flow path 6 between the separator 4 and the separator 4.

  Here, the carbon / phenolic resin composite molding material according to the present invention can uniformly disperse the carbon powder and the rubber-modified phenolic resin even when the carbon powder content is increased to 75% by mass or more as described above. A molded product having a high carbon powder content can be easily molded, and the rubber-modified phenol resin can be satisfactorily filled between the carbon powder particles, and has high electrical conductivity and thermal conductivity. In addition, a molded article having high gas impermeability can be obtained.

  In addition, the flexibility of the phenolic resin is enhanced by rubber modification, which can improve the flexibility of the obtained molded product, and prevents the molded product from being cracked or cracked. It can be done. Here, when the molded article is a separator for a fuel cell as described above, the separator is tightened with a strong force because it is built into the fuel cell by stacking several tens to several hundreds, and vibrates when the fuel cell is used. , Expansion and contraction due to impact and temperature change are easy to act. For this reason, when it is used as a separator for a fuel cell, higher flexibility is required. In the present invention, the test is based on JIS K 7171 “Plastic-Bending Properties Test Method” (1994). It is preferable to have flexibility in which the maximum amount of deflection is 0.5 mm or more. That is, a test piece 10 having a length of 100.0 ± 2.0 mm, a width of 13.0 ± 0.2 mm, and a thickness of 7.0 ± 0.2 mm is produced, and the test piece 10 is placed between fulcrums as shown in FIG. When the bending test is performed by setting on the support bases 11 and 11 having a distance L = 80 mm, pressurizing with the indenter 12, and measuring the deflection S, when the test piece 10 is bent and broken. The amount of deflection is preferably 0.5 mm or more. If the maximum amount of deflection S is 0.5 mm or less, the flexibility of the separator for the fuel cell is insufficient, and there is a possibility that cracking or the like may occur due to the tightening force when stacking a large number of separators into the fuel cell, In addition, cracks and the like may occur due to expansion and contraction due to vibration, impact, and temperature change when the fuel cell is used. Although the upper limit of the maximum amount of deflection S is not particularly set, it is desirable that the upper limit is about 10 mm in practical use.

  Next, the present invention will be specifically described with reference to examples.

Example 1
In a reaction vessel equipped with a stirrer, 115 parts by mass of phenol, 115 parts by mass of bisphenol A, 280 parts by mass of 37% by mass formalin, 7 parts by mass of triethylamine, acrylonitrile-butadiene latex (“Nipol 1561” manufactured by Nippon Zeon Co., Ltd .: 255 parts by mass of a solid content of 40.5% by mass), 1362 parts by mass of scaly graphite powder having an average particle size of 6 μm and a fixed carbon amount of 95.3% by mass, and 1500 parts by mass of water. While stirring and mixing this, the temperature was raised to 90 ° C. over 60 minutes, and the reaction was carried out for 4 hours.

  Next, after cooling to 20 ° C., the contents of the reaction vessel were filtered off with a Nutsche to obtain a water-containing granular material having a water content of 22% by mass. The water-containing granular material is spread to a thickness of about 2 cm on a polyethylene sheet laid on a stainless steel vat, dried in this state for 48 hours in a room, and further placed in a vacuum dryer and dried at 40 ° C. for 5 hours. As a result, a smooth granular carbon-phenol resin composite molding material having a moisture content of 0.4 mass% was obtained.

  The content of graphite in the carbon / phenolic resin composite molding material was 79.8% by mass, and the content of rubber-modified phenolic resin in the carbon / phenolic resin composite molding material was 20.2% by mass. The rubber modification rate of the rubber modified phenolic resin was 29.8% by mass. Furthermore, methanol is added to the carbon / phenolic resin molding material to extract the dissolved components. After the methanol is distilled off, the nitrogen content is measured by the Kjeldahl method, and the measured value is converted into a mass ratio with respect to the rubber-modified phenolic resin. When the nitrogen content in the phenol resin was calculated, the nitrogen content extracted into methanol in the rubber-modified phenol resin was 0.08% by mass.

(Example 2)
In a reaction vessel equipped with a stirrer, phenol, bisphenol A, 37% by mass formalin, triethylamine, and scale graphite powder were charged in the same amount as in Example 1, and the temperature was raised to 90 ° C. over 60 minutes, followed by reaction for 2 hours. . At this point, the same amount of acrylonitrile-butadiene latex was charged as in Example 1, and the reaction was further continued for 2 hours. Others were carried out in the same manner as in Example 1 to obtain a smooth granular carbon-phenol resin composite molding material having a moisture content of 0.3% by mass.

  The content of graphite in the carbon / phenolic resin composite molding material was 79.9% by mass, and the content of rubber-modified phenolic resin in the carbon / phenolic resin composite molding material was 20.1% by mass. The rubber modification rate of the rubber-modified phenol resin was 29.9% by mass, and the nitrogen content was 0.09% by mass.

(Example 3)
In Example 1, instead of acrylonitrile-butadiene latex as rubbers, the same procedure as in Example 1 was used except that 103 parts by mass of nitrile rubber (“Nipol HF01” manufactured by Nippon Zeon Co., Ltd.) was used. A smooth carbon-phenolic resin composite molding material having a moisture content of 0.3% by mass was obtained.

  The content of graphite in the carbon / phenolic resin composite molding material was 79.8% by mass, and the content of rubber-modified phenolic resin in the carbon / phenolic resin composite molding material was 20.2% by mass. The rubber modified phenolic resin had a rubber modification rate of 30.1% by mass and a nitrogen content of 0.07% by mass.

Example 4
In Example 2, instead of acrylonitrile butadiene latex, 240 parts by mass of styrene butadiene latex (“Nipol LX415A” manufactured by Nippon Zeon Co., Ltd .: solid content 43.0% by mass) was used as rubber. In the same manner as in Example 2, a smooth granular carbon / phenolic resin composite molding material having a moisture content of 0.3% by mass was obtained.

  The content of graphite in the carbon / phenolic resin composite molding material was 80.0% by mass, and the content of rubber-modified phenolic resin in the carbon / phenolic resin composite molding material was 20.0% by mass. The rubber modification rate of the rubber-modified phenol resin was 30.0% by mass, and the nitrogen content was 0.06% by mass.

(Comparative Example 1)
Take 200 parts by mass of an alkali resol type phenol resin pulverized to a particle size of 74 μm or less, add methanol to form a slurry, and then add a scaly graphite powder with an average particle size of 100 μm and fixed carbon of 95.3% by mass. 800 parts by mass was added and stirred with a kneader. Further, this was dried at 60 ° C., and then a small amount of magnesium stearate was added and pulverized and mixed with a mixer to obtain a carbon / phenol resin composite molding material.

  The content of graphite in the carbon / phenolic resin composite molding material was 80.0% by mass, and the content of phenolic resin in the carbon / phenolic resin composite molding material was 20.0% by mass. The nitrogen content in the phenol resin was 0.02% by mass.

(Comparative Example 2)
A reaction vessel was charged with 274 parts by weight of phenol, 410 parts by weight of 37% by weight formalin, 30 parts by weight of hexamethylenetetramine, 2107 parts by weight of scaly graphite powder having an average particle size of 6 μm, and 2500 parts by weight of water. . And while stirring this, it took 60 minutes, and it heated up to 90 degreeC, and reacted for 3 hours as it was. Next, after cooling to 20 ° C., the content of the reaction vessel was filtered with Nutsche to obtain a water-containing granular material having a water content of 25% by mass. This water-containing granular material was spread on a polyethylene sheet laid on a stainless steel vat to a thickness of about 2 cm, dried for 48 hours, and further dried in a vacuum dryer at 40 ° C. for 5 hours, A granular carbon / phenolic resin composite molding material of 0.35% by mass was obtained.

  The graphite / polyphenol resin composite molding material had a graphite content of 84.7% by mass and a phenol resin content of 15.3% by mass. The nitrogen content in the phenol resin was 4.1% by mass.

  With respect to the carbon / phenol resin composite molding materials obtained in Examples 1 to 4 and Comparative Examples 1 and 2 as described above, the flow during molding, the loosely packed bulk density, and the particle size were measured. The results are shown in Table 1.

  Here, the flow was measured in accordance with JIS K 6911 “Molding material (disc type flow)” by setting the sample amount to 10 g, the load to 39.2 kN, and the pressing time to 2 minutes.

The loosely packed bulk density was measured using an “ABD powder physical property measuring instrument” manufactured by Tsutsui Rika Kagaku Co., Ltd., and a 100 cm ³ sample container was placed on the measurement disk and the sample was supplied from the upper hopper. The sample was filled with a spatula when the sample container was full, and the total amount of the sample in the sample container was measured. The loosely packed bulk density was calculated from the following equation.
Loosely packed bulk density (g / cm ³ )
= (Sample weight: g) / (Sample container volume: 100 cm ³ )
The particle size was measured using a vibrating sieve device manufactured by Iida Seisakusho.

  Also, the carbon / phenolic resin composite molding materials obtained in Examples 1 to 4 and Comparative Examples 1 to 2 were filled in a mold preheated to 160 ° C. and heated for 3 minutes while being pressed at a surface pressure of about 25 MPa. The molded product was obtained by molding. And using this molded article as a test piece, bending strength, bending elastic modulus, maximum amount of deflection, resistivity, Rockwell hardness, gas permeability, and electrical conductivity were measured. The results are shown in Table 2.

  Here, the measurement of the bending strength, the bending elastic modulus, and the maximum amount of deflection was performed in accordance with JIS K 7171 using a test piece of length 100 mm × width 13 mm × thickness 7 mm. The resistivity was measured in accordance with JIS K 7194 using a test piece having a thickness of 2 mm, and the Rockwell hardness was measured in accordance with JIS K 7202.

  The gas permeability was measured according to JIS K 7126 method B (isobaric method).

  As can be seen from Table 2, the maximum amount of deflection in each example is greater than that in Comparative Examples 1 and 2, and it is confirmed that the flexibility is high. Moreover, the gas permeability of each Example is smaller than the thing of the comparative example 1, and it is confirmed that the electrical conductivity of each Example is lower than the thing of the comparative examples 1 and 2.

It is a schematic sectional drawing which shows the cell of a fuel cell. It is the schematic which shows the test method of a bending characteristic.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrolyte membrane 2 Anode 3 Cathode 4 Separator 5 Gas flow path 6 Gas flow path

Claims (5)

Of a phenol and an aldehyde and rubbers, while mixing with a carbon powder, by polymerization in the presence of a catalyst, carbon phenolic for manufacturing a composite molding material and rubber modified phenolic resin and carbon A method for producing a resin composite molding material, wherein the content of the carbon powder in the composite molding material is 75% by mass or more, and the phenol resin modified with rubber has a rubber modification rate of 5 to 90% by mass. A method for producing a carbon-phenol resin composite molding material for molding a fuel cell separator . 2. The method for producing a carbon-phenol resin composite molding material for molding a fuel cell separator according to claim 1, wherein acrylonitrile-butadiene rubber is used as the rubber. The carbon-phenol resin composite molding material produced by the method for producing a carbon-phenol resin composite molding material according to claim 1 or 2 is molded into a thin plate-like molded body having a predetermined flow path pattern. A fuel cell separator. 4. The fuel cell separator according to claim 3 , wherein the rubber-modified phenolic resin in the carbon / phenolic resin composite molding material has a nitrogen content of 0.3% by mass or less extracted into methanol. In accordance with JIS K 7171 “Plastics-Testing method for bending properties”, the maximum amount of deflection at break when a test piece having a length of 100 mm, a width of 13 mm, and a thickness of 7 mm is tested at a distance between fulcrums of 80 mm is 0. The fuel cell separator according to claim 3 or 4 , wherein the separator is 5 mm or more.

Images