JP6132239B2 - Manufacturing method of fuel cell separator - Google Patents

Description

The present invention relates to a method for manufacturing a fuel cell separator which is applied to a fuel cell.

  In general, a fuel cell is composed of a cell stack composed of several tens to several hundreds of unit cells stacked in series. Fuel cells are classified into several types based on the type of electrolyte. In recent years, a polymer electrolyte fuel cell provided with a polymer electrolyte membrane has attracted attention as a high-power fuel cell.

  A unit cell of a fuel cell is configured by, for example, stacking a fuel cell separator, a gasket, and a membrane-electrode composite.

  Of the components constituting the fuel cell, the fuel cell separator includes a gas distribution groove and a manifold for supplying gas to the groove. The fuel cell separator has a function to separate the fuel flowing in the fuel cell, the oxidant and the cooling water so as not to mix, a function to transmit the electric energy generated by the fuel cell to the outside, and the heat generated by the fuel cell to the outside It plays an important function of heat dissipation.

  Since the voltage of this fuel cell depends on the number of stacked unit cells, it is necessary to increase the number of stacked unit cells in order to increase the voltage of the fuel cell. However, when the number of stacks increases, the bulk of the fuel cell increases, which causes a problem that miniaturization of the fuel cell is hindered, and a problem of cost increase due to a complicated stacking process.

  Therefore, in Patent Document 1, it is proposed that a plurality of portions having conductivity are formed in the fuel cell separator by partitioning the inside of the fuel cell separator with portions having electrical insulation. In this case, one unit cell composed of the fuel cell separator can substantially function as a plurality of unit cells. Therefore, the voltage of the fuel cell can be increased without increasing the number of unit cells stacked.

International Publication No. WO2012 / 081792

  However, since the conventional fuel cell separator is a homogeneous member having conductivity as a whole, a portion having electrical insulation and a plurality of portions having conductivity are formed in the fuel cell separator. No method has yet been established. In addition, when a fuel cell separator is manufactured by separately forming a part having electrical insulation and a plurality of parts having conductivity and joining these parts, the number of man-hours required for the production increases. As a result, the manufacturing efficiency of the fuel cell separator is reduced.

The present invention has been made in view of the above reasons, and in manufacturing a fuel cell separator including a portion having electrical insulation and a plurality of portions having conductivity, these portions can be formed simultaneously. It is an object of the present invention to provide a method for manufacturing a separator for a fuel cell.

A method for manufacturing a fuel cell separator according to a first aspect of the present invention is a method for manufacturing a fuel cell separator including a central portion having a gas flow groove and an outer peripheral portion surrounding the central portion by a compression molding method. A way to
A conductive molding material and an electrically insulating molding material are disposed in a compression molding mold, and the conductive molding material and the electrical insulating molding material are simultaneously compression molded in the compression molding mold, A central portion of the fuel cell separator is composed of an insulating portion formed from the electrically insulating molding material and a plurality of conductive portions formed from the conductive molding material and divided by the insulating portion. Features.

  In the method for manufacturing a fuel cell separator according to the second aspect of the present invention, in the first aspect, the outer peripheral portion is constituted by a second insulating portion formed from the electrically insulating molding material.

  In the method for manufacturing a fuel cell separator according to the third aspect of the present invention, the conductive molding material and the electrically insulating molding material are both in powder form, and the value of the disk flow of the conductive molding material. However, it is smaller than the disk flow value of the electrically insulating molding material, and the difference between these disk flow values is in the range of more than 0 mm and not more than 10 mm.

  In the method for manufacturing a fuel cell separator according to the fourth aspect of the present invention, at least one of the electrically insulating molding material and the conductive molding material has a sheet shape.

  In the fuel cell separator manufacturing method according to the fifth aspect of the present invention, in any one of the first to fourth aspects, the conductive molding material contains an epoxy resin and a phenolic curing agent.

  In the fuel cell separator manufacturing method according to the sixth aspect of the present invention, in the first to fifth aspects, the electrically insulating molding material contains an epoxy resin and a phenolic curing agent.

In the method for producing a fuel cell separator according to the seventh aspect of the present invention, in any one of the first to sixth aspects, the conductive molding material contains an epoxy resin and a phenol-based curing agent,
The electrical insulating molding material contains an epoxy resin and a phenolic curing agent,
The equivalent value of the phenolic curing agent with respect to 1 equivalent of the epoxy resin in the conductive molding material is less than 1, and the equivalent of the phenolic curing agent with respect to 1 equivalent of the epoxy resin in the electrically insulating molding material. Is greater than 1 or
The value of the equivalent of the phenolic curing agent with respect to 1 equivalent of the epoxy resin in the conductive molding material is larger than 1, and the phenolic curing agent with respect to 1 equivalent of the epoxy resin in the electrically insulating molding material. The equivalent value is less than 1.

  In the method for manufacturing a fuel cell separator according to the eighth aspect of the present invention, in any one of the first to seventh aspects, the ratio of the linear expansion coefficient of the insulating portion to the conductive portion is set to 1 / Within the range of 5-5.

  A fuel cell separator according to a ninth aspect of the present invention is manufactured by the method according to any one of the first to eighth aspects.

  According to the present invention, since the insulating portion and the plurality of conductive portions can be simultaneously formed by compression molding and the insulating portion and the conductive portion can be joined, a fuel cell including the insulating portion and the plurality of conductive portions. The production efficiency of the separator is improved.

It is general | schematic sectional drawing which shows the manufacturing process of the separator for fuel cells in one Embodiment of this invention. It is general | schematic sectional drawing which shows the manufacturing process of the separator for fuel cells in this embodiment. It is general | schematic sectional drawing which shows the manufacturing process of the separator for fuel cells in this embodiment. It is a top view by the side of the 1st main surface of the separator for fuel cells which concerns on this embodiment. It is a top view by the side of the 2nd main surface of the separator for fuel cells which concerns on this embodiment.

  Embodiments of the invention will be described below.

  In the method for manufacturing a fuel cell separator 1 (hereinafter referred to as separator 1) according to the present embodiment, a separator 1 (including a central portion 4 provided with a gas flow groove 10 and an outer peripheral portion 5 surrounding the central portion 4 ( 4 and 5) are manufactured by compression molding. In this case, as shown in FIGS. 1 to 3, the conductive molding material 8 and the electrically insulating molding material 9 are arranged in the compression molding die 7, and the conductive molding material 8 and the electrically insulating molding material 9 are disposed. Then, compression molding is simultaneously performed in the compression mold 7. Thus, the central portion 4 of the separator 1 is divided into an insulating portion 3 formed from the electrically insulating molding material 9 and a plurality of conductive portions 2 formed from the conductive molding material 8 and divided by the insulating portion 3. Configure. 1 to 3 show an outline of the manufacturing method according to the present embodiment, and the illustration of the gas flow groove 10 is omitted.

  Since the separator 1 obtained in this way includes a plurality of conductive portions 2 that are electrically insulated from each other by the insulating portions 3, one unit cell constituted by the separator 1 is substantially a plurality of unit cells. Can function as. For this reason, the power generation efficiency of a fuel cell provided with this unit cell becomes high. Moreover, since the conductive portion 2 and the insulating portion 3 are simultaneously formed by compression molding, the separator 1 is efficiently manufactured.

  Hereinafter, this embodiment will be described in more detail.

  The separator 1 obtained in this embodiment has a flat plate shape and includes a first main surface 21 and a second main surface 22 located on the opposite side of the first main surface 21.

  A separator 1 according to this embodiment is shown in FIGS. 4 is a plan view of the separator 1 on the first main surface 21 side, and FIG. 5 is a plan view of the separator 1 on the second main surface 22 side.

  In the present embodiment, a gas flow groove 10 is formed on the first main surface 21 of the separator 1. The separator 1 includes a portion including the groove 10 (hereinafter also referred to as the central portion 4) and a portion surrounding the central portion 4 and not including the groove 10 (hereinafter also referred to as the outer peripheral portion 5). The groove 10 is formed over the entire central portion 4 on the first main surface 21. In the present embodiment, the separator 1 is formed with a hole (manifold) 24 that penetrates the outer peripheral portion 5. In this embodiment, the manifold 24 includes four manifolds 24 for gas circulation (first manifold 241, second manifold 242, third manifold 243, and fourth manifold 244) and two refrigerant circulation channels. One manifold 24 (fifth manifold 245 and sixth manifold 246) is included.

  Further, in the outer peripheral portion 5, a recess 25 (first recess 251) that communicates the groove 10 and the first manifold 241 and a recess 25 (first recess) that communicates the groove 10 and the second manifold 242. Two recesses 252) are formed. Thereby, the groove 10 in the first main surface 21 communicates with the first manifold 241 and the second manifold 242 and does not communicate with the third to sixth manifolds 243 to 246.

  In the central portion 4 of the separator 1, a coolant circulation groove 11 is formed in the second main surface 22. The groove 11 communicates with the fifth manifold 245 and the sixth manifold 246 and does not communicate with the first to fourth manifolds 241 to 244.

  A unit cell of the fuel cell is configured by stacking the separator 1 and the membrane-electrode assembly.

  In the present embodiment, the separator 1 includes a plurality of conductive portions 2 having conductivity, an insulating portion 3 having electrical insulation, and a second insulation portion 6 having electrical insulation. The conductive part 2 and the insulating part 3 constitute a central part 4. Moreover, the 2nd insulation part 6 comprises the outer peripheral part 5, Therefore, the outer peripheral part 5 has electrical insulation over the whole.

  In the present embodiment, since the outer peripheral portion 5 is composed of the second insulating portion 6 formed from the electrically insulating molding material 9, the second insulating portion 6 is composed of the unit cell composed of the separator 1 and the outside thereof. The electrical insulation between the two can be ensured. In addition, since electrical insulation is provided around the manifold 24, electrolytic corrosion of the separator 1 around the manifold 24 is suppressed.

  Note that the separator 1 may not include the second insulating portion 6. In that case, the whole outer peripheral part 5 may have electroconductivity, and the outer peripheral part 5 may have electroconductivity partially while it has electroconductivity partially.

  An insulating part 3 is interposed between the adjacent conductive parts 2. For this reason, any conductive part 2 is electrically insulated from other conductive parts 2. 4 and 5, the separator 1 includes four conductive portions 2, and these conductive portions 2 are arranged in a matrix. However, the number of the conductive portions 2 and how to arrange the conductive portions 2 are as follows. It is not limited to this. For example, the separator 1 may include two conductive parts 2.

  The conductive portion 2 is formed from a conductive molding material 8. In the present embodiment, the conductive molding material 8 contains a thermosetting resin and a conductive material.

  The conductive material is particularly preferably graphite particles. By using the graphite particles, the electrical resistivity of the conductive portion 2 is reduced, and the conductivity of the conductive portion 2 is improved. The proportion of the graphite particles in the conductive molding material 8 is preferably in the range of 60 to 90% by mass with respect to the total solid content in the conductive molding material 8. That is, it is preferable that the ratio of the graphite particle in the electroconductive part 2 exists in the range of 60-90 mass%. When the proportion of the graphite particles is 60% by mass or more, sufficiently excellent conductivity is imparted to the conductive portion 2, and when the proportion is 90% by mass or less, the conductive molding material 8 is sufficient. In addition to providing excellent moldability, the conductive portion 2 is provided with sufficiently excellent gas permeability. More preferably, the ratio of the graphite particles is in the range of 65 to 80% by mass.

  The graphite particles may be any of artificial graphite powder and natural graphite powder. Natural graphite powder has the advantage of high conductivity, and artificial graphite powder has the advantage of low anisotropy, although the conductivity is somewhat inferior to that of natural graphite powder. For example, graphite particles are graphite particles obtained by graphitizing carbonaceous materials such as mesocarbon microbeads, graphite particles obtained by graphitizing coal-based coke and petroleum-based coke, processed powder of graphite electrodes and special carbon materials, natural graphite One or more materials selected from the group consisting of quiche graphite and expanded graphite can be contained. In particular, considering the characteristics of these materials, it is preferable that the graphite particles contain two or more materials.

  The graphite particles are preferably purified. In this case, since the content of ash and ionic impurities in the graphite particles is low, elution of impurities from the conductive portion 2 is suppressed.

  The average particle size of the graphite particles is preferably in the range of 10 to 200 μm. When the average particle diameter is 10 μm or more, the moldability of the conductive molding material 8 is improved. If the average particle size is 30 μm or more, better results can be obtained. Moreover, if this average particle diameter is 150 micrometers or less, the surface smoothness of the electroconductive part 2 will further improve.

  The average particle diameter of the graphite particles is a volume average particle diameter measured by a laser diffraction scattering method with a laser diffraction / scattering particle size analyzer (such as Microtrac MT3000II series manufactured by Nikkiso Co., Ltd.).

  Thermosetting resins include, for example, epoxy resins, thermosetting phenol resins, vinyl ester resins, polyimide resins, unsaturated polyester resins, diallyl phthalate resins, polyester resins, urea resins, melamine resins, silicone resins, vinyl ester resins, and benzoates. One or more resins selected from oxazine resins can be contained. Among these, it is preferable to use one or more resins selected from benzoxazine resins, epoxy resins, and thermosetting phenol resins. In this case, the heat resistance and mechanical strength of the conductive portion 2 are particularly high.

  When an epoxy resin is used, the epoxy resin is selected from the group consisting of an ortho cresol novolac type epoxy resin, a bisphenol type epoxy resin, a biphenyl type epoxy resin, a phenol aralkyl type epoxy resin having a biphenylene skeleton, and a naphthalene type epoxy resin. It is preferable to contain one or more resins. These resins are excellent in that they have a good melt viscosity and a small amount of impurities, in particular, a small amount of ionic impurities.

  When an epoxy resin is used, the conductive molding material 8 further contains an epoxy resin curing agent. Although it will not specifically limit if a hardening | curing agent has the capability to harden an epoxy resin, It is preferable to make a phenol type hardening | curing agent an essential component. This phenolic curing agent contains at least one selected from various polyhydric phenol resins such as phenol novolac resin, cresol novolac resin, phenol aralkyl resin, naphthol aralkyl resin, and the like. When a phenolic curing agent is used, the equivalent value of the phenolic curing agent with respect to 1 equivalent of epoxy resin is preferably in the range of 0.8 to 1.2.

  When a thermosetting phenol resin is used as the thermosetting resin, it is particularly preferable to use a phenol resin that undergoes a polymerization reaction by ring-opening polymerization. An example of such a phenolic resin is a benzoxazine resin. In this case, since gas due to dehydration is not generated in the molding process, voids are hardly generated in the molded product, and a decrease in gas permeability of the separator 1 is suppressed. It is also preferable to use a resol type phenol resin. For example, as a result of 13C-NMR analysis, ortho-ortho bond ratio 25 to 35%, ortho-para bond ratio 60 to 70%, para-para bond ratio 5 to 10%. It is preferable to use a resol type phenolic resin having a structure of The resol resin is usually in a liquid state, but the resol type phenol resin can easily adjust the softening point, and a resol type phenol resin having a melting point of 70 to 90 ° C. can be easily obtained. Thereby, the change of the electroconductive molding material 8 decreases, and the handleability at the time of shaping | molding improves. When the melting point is less than 70 ° C., the components are likely to aggregate in the conductive molding material 8 and the handling property may be lowered.

  The thermosetting resin component may contain a catalyst (curing accelerator) as necessary. Examples of the catalyst include organic phosphines such as triphenylphosphine, tertiary amines such as 1,8-diazabicyclo (5,4,0) undecene-7, and imidazoles such as 2-methylimidazole. The content of the catalyst in the conductive molding material 8 is preferably in the range of 0.5 to 3% by mass with respect to the total amount of the thermosetting resin and the curing agent in the conductive molding material 8.

  As a catalyst, the weight loss when heated under the conditions of a measurement start temperature of 30 ° C., a heating rate of 10 ° C./min, a holding temperature of 120 ° C., and a holding time of 30 minutes at a holding temperature of 5% or less is second, Substituted imidazoles having hydrocarbon groups may be used. As this substituted imidazole, a substituted imidazole having 6 to 17 carbon atoms in the 2-position hydrocarbon group is particularly preferable. Specific examples of this substituted imidazole include 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-benzyl-2-phenylimidazole and the like.

  The conductive molding material 8 may further contain an internal mold release agent. As the internal mold release agent, an appropriate one is used. In particular, the internal mold release agent is compatible with the thermosetting resin and the hardener in the conductive molding material 8 at 120 to 190 ° C. It preferably has the property of separating. As such an internal mold release agent, it is preferable to use one or more materials selected from polyethylene wax, carnauba wax, and long-chain fatty acid wax. Such an internal mold release agent is phase-separated from the thermosetting resin and the curing agent in the molding process of the conductive molding material 8, so that the mold release improving effect is satisfactorily exhibited.

  The amount of the internal mold release agent used is appropriately set in consideration of the complexity of the shape of the separator 1, the groove depth, the ease of releasability from the mold surface such as the draft angle, and the like. In particular, the ratio of the internal mold release agent to the total amount of the conductive molding material 8 is preferably in the range of 0.1 to 2.5% by mass. When this proportion is 0.1% by mass or more, sufficient releasability is exhibited at the time of molding the mold, and when this proportion is 2.5% by mass or less, the hydrophilicity of the surface of the separator 1 is increased by the internal mold release agent. Inhibition is sufficiently suppressed. The ratio of the internal mold release agent is more preferably in the range of 0.1 to 1% by mass, and particularly preferably in the range of 0.1 to 0.5% by mass.

  The conductive molding material 8 may contain an additive such as a coupling agent as necessary. Examples of the coupling agent include silicon-based silane compounds, titanate-based, and aluminum-based coupling agents. In particular, an epoxy silane coupling agent is suitable among silicon coupling agents. The coupling agent may be previously attached to the surface of the graphite particles by spraying or the like. It is preferable that the usage-amount of an epoxy silane coupling agent exists in the range of 0.5-1.5 mass% with respect to the whole solid content of the electroconductive molding material 8. FIG. Within this range, bleeding of the coupling agent to the surface of the separator 1 is sufficiently suppressed.

  The conductive molding material 8 may further contain short fibers such as carbon fibers and metal fibers. In addition, the conductive molding material 8 may contain various additives as long as the functions necessary for the separator 1 are ensured.

  The conductive molding material 8 is prepared, for example, by mixing the above components in a predetermined ratio in an arbitrary order. For mixing the components, for example, a mixer such as a planetary mixer, a ribbon blender, a Redige mixer, a Henschel mixer, a rocking mixer, or a Nauta mixer is used. Thereby, for example, a powdery conductive molding material 8 is obtained.

  The conductive molding material 8 may be in the form of a sheet. In this case, for example, the above-described components are first blended, and further a solvent is blended to prepare a varnish. The solvent can contain one or more selected from polar solvents such as methyl ethyl ketone, methoxypropanol, N, N-dimethylformamide, dimethyl sulfoxide, and the like. By forming this varnish, a sheet-like conductive molding material 8 is obtained. The varnish is formed into a sheet shape by, for example, casting (progressive) forming. The sheet-like conductive molding material 8 is formed into a predetermined shape by being cut or punched as necessary. In particular, the conductive molding material 8 is preferably formed in a shape that matches the conductive portion 2.

  The insulating part 3 and the second insulating part 6 are formed from an electrically insulating molding material 9. In this embodiment, the electrically insulating molding material 9 contains a thermosetting resin.

  Examples of the thermosetting resin in the electrically insulating molding material 9 include epoxy resin, thermosetting phenol resin, vinyl ester resin, polyimide resin, unsaturated polyester resin, diallyl phthalate resin, polyester resin, urea resin, melamine resin, and silicone. One or more resins selected from the group consisting of a resin, a vinyl ester resin, and a benzoxazine resin can be contained. Among these, it is preferable to use one or more resins selected from the group consisting of benzoxazine resin, epoxy resin, and thermosetting phenol resin. In this case, the heat resistance and mechanical strength of the insulating part 3 and the second insulating part 6 are particularly high.

  When an epoxy resin is used, the epoxy resin is one or more resins selected from the group consisting of ortho-cresol novolac type epoxy resins, bisphenol type epoxy resins, biphenyl type epoxy resins, and phenol aralkyl type epoxy resins having a biphenylene skeleton. It is preferable to contain. These resins are excellent in that they have a good melt viscosity and a small amount of impurities, in particular, a small amount of ionic impurities.

  When an epoxy resin is used, the electrically insulating molding material 9 further contains an epoxy resin curing agent. Although it will not specifically limit if a hardening | curing agent has the capability to harden an epoxy resin, It is preferable to make a phenol type hardening | curing agent an essential component. This phenolic curing agent contains one or more compounds selected from the group consisting of various polyphenol resins such as phenol novolak resin, cresol novolak resin, phenol aralkyl resin, naphthol aralkyl resin and the like. When a phenolic curing agent is used, it is preferable that the equivalent of the epoxy resin with respect to 1 equivalent of the phenolic curing agent is in the range of 0.8 to 1.2.

  The electrically insulating molding material 9 may contain an electrically insulating filler. The electrically insulating filler is, for example, one or more selected from the group consisting of fused silica, crystalline silica, calcium carbonate, magnesium carbonate, alumina, silicon nitride, magnesia, clay, talc, calcium silicate, asbestos, glass fiber, and glass sphere. Materials can be included.

  The ratio of the electrically insulating filler to the total solid content of the electrically insulating molding material 9 is preferably in the range of 60 to 93% by mass. When this proportion is 60% by mass or more, the heat resistance of the insulating portion 3 and the second insulating portion 6 is particularly high. The ratio of the electrically insulating filler is preferably 85% by mass or more. Moreover, a moldability becomes favorable in the ratio of this electrically insulating filler being 93 mass% or less.

  The average particle size of the electrically insulating filler is preferably in the range of 5 to 20 μm. This average particle diameter is a volume average particle diameter measured by a laser diffraction scattering method.

  The electrically insulating molding material 9 may contain an internal mold release agent. In particular, the internal mold release agent preferably has a property of phase separation at 120 to 190 ° C. without being incompatible with the thermosetting resin and the curing agent in the electrically insulating molding material 9. As such an internal mold release agent, it is preferable to use one or more materials selected from polyethylene wax, carnauba wax, and long-chain fatty acid wax. Such an internal release agent is phase-separated from the thermosetting resin and the curing agent in the molding process of the electrically insulating molding material 9, so that the effect of improving the release property is satisfactorily exhibited.

  The amount of the internal mold release agent used is appropriately set in consideration of the complexity of the shape of the separator 1, the groove depth, the ease of releasability from the mold surface such as the draft angle, and the like. In particular, the ratio of the internal mold release agent to the total amount of the electrically insulating molding material 9 is preferably in the range of 0.1 to 2.5% by mass. When this proportion is 0.1% by mass or more, sufficient releasability is exhibited at the time of molding the mold, and when this proportion is 2.5% by mass or less, the hydrophilicity of the surface of the separator 1 is increased by the internal mold release agent. Inhibition is sufficiently suppressed. The ratio of the internal mold release agent is more preferably in the range of 0.1 to 1% by mass, and particularly preferably in the range of 0.1 to 0.5% by mass.

  The electrically insulating molding material 9 may contain an additive such as a coupling agent as necessary. Examples of the coupling agent include silicon-based silane compounds, titanate-based, and aluminum-based coupling agents. In particular, an epoxy silane coupling agent is suitable among silicon coupling agents. It is preferable that the usage-amount of an epoxy silane coupling agent exists in the range of 0.5-1.5 mass% with respect to the whole solid content of the electrically insulating molding material 9. FIG. Within this range, bleeding of the coupling agent to the surface of the separator 1 is sufficiently suppressed.

  The electrically insulating molding material 9 may further contain various additives as long as the functions necessary for the separator 1 are ensured.

  The electrically insulating molding material 9 is prepared, for example, by mixing the above components in a predetermined ratio in an arbitrary order. For mixing the components, for example, a mixer such as a planetary mixer, a ribbon blender, a Redige mixer, a Henschel mixer, a rocking mixer, or a Nauta mixer is used. Thereby, for example, a powdery electrically insulating molding material 9 is obtained.

  In order to adjust the fluidity at the time of molding the electrically insulating molding material 9, the electrically insulating molding material 9 may be subjected to heat treatment. The heating temperature in the heat treatment is set, for example, within a range of 25 to 80 ° C. The heating time in the heat treatment is set within a range of 1 to 60 hours, for example.

  The electrically insulating molding material 9 may be in the form of a sheet. In this case, for example, the above-described components are first blended, and further a solvent is blended to prepare a varnish. The solvent can contain one or more selected from polar solvents such as methyl ethyl ketone, methoxypropanol, N, N-dimethylformamide, dimethyl sulfoxide, and the like. By forming this varnish, a sheet-like electrically insulating molding material 9 is obtained. The varnish is formed into a sheet shape by, for example, casting (progressive) forming.

  Moreover, after impregnating varnish in base materials, such as a glass woven fabric, a glass nonwoven fabric, and paper, the sheet-like electrically insulating molding material 9 provided with a base material may be obtained by heat-drying.

  The sheet-like electrically insulating molding material 9 is formed into a predetermined shape by being cut or punched as necessary. In particular, the electrically insulating molding material 9 is preferably formed into a shape that matches the insulating portion 3.

  When the electrically insulating molding material 9 contains an epoxy resin and a phenolic curing agent, it is preferable that the conductive molding material 8 contains an epoxy resin and a phenol resin. In this case, the adhesion between the conductive part 2 and the insulating part 3 and the adhesion between the conductive part 2 and the second insulating part 6 are enhanced.

  In particular, the equivalent value of the phenolic curing agent with respect to 1 equivalent of epoxy resin in the conductive molding material 8 is less than 1, and the equivalent value of the phenolic curing agent with respect to 1 equivalent of epoxy resin in the electrically insulating molding material 9. Is preferably greater than 1. In this case, an unreacted epoxy group remains in the conductive part 2 and an unreacted hydroxyl group remains in the insulating part 3, and this epoxy group and the hydroxyl group easily react with each other. Improved adhesion. Further, an unreacted epoxy group remains in the conductive part 2 and an unreacted hydroxyl group remains in the second insulating part 6, and this epoxy group and the hydroxyl group easily react with each other. Adhesion with the part 6 is improved. In particular, the equivalent value of the phenolic curing agent with respect to 1 equivalent of epoxy resin in the conductive molding material 8 is in the range of 0.8 to 0.95, and with respect to 1 equivalent of epoxy resin in the electrically insulating molding material 9. It is preferable that the equivalent value of the phenolic curing agent is within a range of 1.05 to 1.2. In this case, the adhesion between the conductive portion 2 and the insulating portion 3 is particularly improved, and elution of the unreacted epoxy resin and the phenolic curing agent from the unreacted conductive portion 2 and the insulating portion 3 is suppressed.

  The equivalent value of the phenolic curing agent with respect to 1 equivalent of epoxy resin in the conductive molding material 8 is larger than 1, and the equivalent value of the phenolic curing agent with respect to 1 equivalent of epoxy resin in the electrically insulating molding material 9 is 1. It is also preferable that it is less than. In this case, an unreacted hydroxyl group remains in the conductive portion 2 and an unreacted epoxy group remains in the insulating portion 3, and this hydroxyl group and the epoxy group easily react with each other. Improved adhesion. Further, an unreacted hydroxyl group remains in the conductive portion 2 and an unreacted epoxy group remains in the second insulating portion 6, and this hydroxyl group and the epoxy group easily react with each other. Adhesion with the part 6 is improved. In particular, the equivalent value of the phenol-based curing agent with respect to 1 equivalent of epoxy resin in the conductive molding material 8 is in the range of 1.05 to 1.2, and with respect to 1 equivalent of epoxy resin in the electrically insulating molding material 9. It is preferable that the equivalent value of the phenol-based curing agent is in the range of 0.8 to 0.95. In this case, the adhesion between the conductive portion 2 and the insulating portion 3 is particularly improved, and elution of the unreacted epoxy resin and the phenolic curing agent from the unreacted conductive portion 2 and the insulating portion 3 is suppressed.

  In manufacturing the separator 1, first, as shown in FIG. 1, a conductive molding material 8 and an electrically insulating molding material 9 are arranged in a compression mold 7. At this time, the conductive molding material 8 is disposed at a position corresponding to the conductive portion 2 in the compression molding die 7, and the electrically insulating molding material 9 is disposed at a position corresponding to the insulating portion 3 and the second insulating portion 6. The

  Next, as shown in FIG. 2, the conductive molding material 8 and the electrically insulating molding material 9 are simultaneously compression molded in the compression molding die 7. Thus, the conductive molding material 8 is molded and cured to form the conductive portion 2, and the electrically insulating molding material 9 is molded and cured to form the insulating portion 3 and the second insulating portion 6. Is done. Further, the conductive portion 2, the insulating portion 3, and the second insulating portion 6 are joined and integrated to constitute the separator 1. After compression molding, after the compression molding die 7 is cooled, the separator 1 is taken out from the compression molding die 7 as shown in FIG.

  Thus, in this embodiment, the conductive part 2 and the insulating part 3 are simultaneously formed by compression molding. Further, in the present embodiment, the second insulating portion 6 constituting the outer peripheral portion 5 is also formed simultaneously with the conductive portion 2 and the insulating portion 3. For this reason, the separator 1 provided with the electroconductive part 2, the insulating part 3, and the 2nd insulating part 6 is manufactured efficiently.

  In the present embodiment, particularly when the conductive molding material 8 and the electrically insulating molding material 9 are both in the form of powder, the value of the disk flow of the conductive molding material 8 is that of the electrically insulating molding material 9. It is preferably smaller than the value of the disk flow. In this case, it becomes difficult for the electrically insulating molding material 9 to flow into the region where the insulating portion 3 is to be formed during molding. For this reason, it becomes difficult for the electrically insulating molding material 9 to hinder the electrical insulation of the insulating portion 3. Furthermore, it is preferable that the difference between the value of the disk flow of the conductive molding material 8 and the value of the disk flow of the electrically insulating molding material 9 is in the range of more than 0 mm and not more than 10 mm. In this case, the difference between the fluidity of the conductive molding material 8 and the fluidity of the electrically insulating molding material 9 at the time of molding is less likely to increase, so that the conductive portion 2 and the insulating portion 3 have a desired shape. It becomes easier to form. The difference in the disk flow values is particularly preferably in the range of more than 0 mm and not more than 5 mm.

  In addition, the value of the disk flow is such that a 3 g sample is densely arranged at one place on a flat surface, and when this is compressed for 30 seconds under the conditions of a temperature of 170 ° C. and a pressure of 5 MPa, It is a measured value of (longest diameter).

  The disk flow of the conductive molding material 8 and the electrically insulating molding material 9 can be easily adjusted by adjusting the raw material composition of each molding material. For example, if the ratio of the resin component in each molding material is increased, or if a resin having a lower melt viscosity is blended in the resin component, the disk flow increases, the ratio of the resin component in each molding material decreases, or the resin If a resin having a higher melt viscosity is blended with the component, the disk flow is reduced.

  In this embodiment, particularly when the conductive molding material 8 molded into a sheet shape is used, the conductive molding material 8 is easily disposed at a position corresponding to the conductive portion 2 in the compression molding die 7. . For this reason, even if the conductive part 2 and the insulating part 3 are simultaneously formed by compression molding, the size and shape of the conductive part 2 can be easily controlled.

  Further, in the present embodiment, particularly when the electrically insulating molding material 9 formed into a sheet shape is used, the electrically insulating molding material 9 can be easily positioned at a position corresponding to the insulating portion 3 in the compression molding die 7. Placed in. For this reason, even if the conductive part 2 and the insulating part 3 are simultaneously formed by compression molding, the size and shape of the insulating part 3 can be easily controlled. Moreover, in this embodiment, since the 2nd insulation part 6 is also formed from the electrically insulating molding material 9, the dimension and shape of the 2nd insulation part 6 can also be controlled easily.

  In addition, a region where the conductive molding material 8 and the electrically insulating molding material 9 are mixed (hereinafter referred to as a mixed region) may be formed in the boundary region between the conductive portion 2 and the insulating portion 3. However, if the conductive molding material 8 and the electrically insulating molding material 9 are both in the form of a sheet, the conductive molding material 8 and the electrically insulating molding material 9 are difficult to be mixed. Even if it occurs, its width is reduced.

  The compression molding is preferably performed in a state where the compression molding die 7 is disposed under a reduced pressure condition or a vacuum condition. In this case, the density variation of the separator 1 is reduced and the thickness accuracy of the separator 1 is increased. In particular, the degree of vacuum around the compression mold 7 is preferably 80 kPa or more, and more preferably 95 kPa or more. The upper limit of the degree of vacuum is not particularly limited, but is practically up to 100 kPa.

  Although the heating temperature and compression pressure at the time of compression molding depend on the composition of the conductive molding material 8 and the electrically insulating molding material 9, the molding thickness, etc., for example, within the range of the heating temperature of 120 to 190 ° C., the compression pressure of 1 to 40 MPa. It is preferable to set within the range. The molding time is preferably set within a range of 15 seconds to 600 seconds.

  In the separator 1 thus obtained, the ratio of the linear expansion coefficient of the insulating part 3 to the linear expansion coefficient of the conductive part 2 is preferably in the range of 1/5 to 5. In this case, it is difficult for the separator 1 to warp during compression molding. Moreover, since the deformation | transformation and damage of the separator 1 when the separator 1 is heated are suppressed, the thermal shock resistance of the separator 1 becomes high. Thereby, the long-term durability of the separator 1 is improved.

  When the separator 1 includes the second insulating portion 6 as in the present embodiment, the value of the ratio of the linear expansion coefficient of the second insulating portion 6 to the linear expansion coefficient of the conductive portion 2 is also in the range of 1/5 to 5. It is preferable to be within. Moreover, it is preferable that the value of the ratio of the linear expansion coefficient of the second insulating part 6 to the linear expansion coefficient of the insulating part 3 is also in the range of 1/5 to 5.

  The linear expansion coefficient of the conductive part 2, the linear expansion coefficient of the insulating part 3, and the linear expansion coefficient of the second insulating part 6 are controlled by appropriately setting the composition of the conductive molding material 8 and the electrically insulating molding material 9. Is done. For example, the linear expansion coefficient of the conductive portion 2 is controlled by setting the type of resin constituting the conductive molding material 8, the blending ratio of the conductive particles in the conductive molding material 8, and the like. Moreover, the linear expansion coefficient of the insulating part 3 is controlled by setting the kind of resin constituting the electrically insulating molding material 9, the blending ratio of the insulating filler in the electrically insulating molding material 9, and the like.

  The separator 1 taken out from the compression mold 7 may be further subjected to heat treatment. The heating temperature in this heat treatment is preferably in the range of 150 to 180 ° C., and the heating time is preferably in the range of 30 seconds to 1 hour.

  The separator 1 may be subjected to blasting such as wet blasting. As a result, the skin layer on the surface of the separator 1 is removed and the roughness of the surface of the separator 1 is adjusted. It is preferable that the arithmetic average height Ra (JIS B0601: 2001) of the surface of the separator 1 is adjusted within a range of 0.4 to 1.6 μm by blasting.

  It is also preferable that the separator 1 is subjected to a hydrophilization treatment after the wet blast treatment. Moreover, it is also preferable that after the wet blasting process, the separator 1 is subjected to a cleaning process, or after the cleaning process, a drying process is further performed, and then a hydrophilic process is performed. In the washing process, for example, the separator 1 is washed with ion exchange water or the like. In the drying process, the separator 1 is preferably dried until the moisture absorption rate is 0.1% or less.

  The hydrophilization treatment is a treatment for improving the hydrophilicity of the inner surface of the gas flow groove 10. Thereby, high hydrophilicity is provided to the inner surface of the groove 10 for gas flow. The hydrophilic treatment may be performed over the entire surface of the separator 1 where the grooves 10 are formed.

  Examples of hydrophilization treatment include plasma treatment in which the molded body is exposed to plasma, ozone gas treatment in which the molded body is exposed to ozone gas, SO3 treatment in which the molded body is exposed to SO3, fluorine treatment in which the molded body is exposed to a gas containing fluorine, One or more treatments are selected from the group consisting of flame treatment in which a gas containing a modifier compound including a silicon compound or an aluminum compound is burned and sprayed onto a molded body, and ozone water treatment in which ozone water is brought into contact with the molded body. . In particular, it is preferable to employ plasma treatment.

  Examples of the present invention will be described below. The present invention is not limited to these examples.

[Examples 1 to 11]
For each example, a separator having the configuration shown in FIGS. 4 and 5 was produced as follows.

(Preparation of conductive molding material)
In Examples 1 to 5 and 7 to 11, an epoxy resin, a phenol-based curing agent, a curing accelerator, graphite particles, a coupling agent, and a wax are added to a stirring mixer (“5XDMV-rr type” manufactured by Dalton). The mixture shown in the table was stirred and mixed, and the resulting mixture was pulverized to a particle size of 500 μm or less with a granulator. Thereby, a powdery conductive molding material was obtained.

  In Example 6, an epoxy resin, a phenolic curing agent, a curing accelerator, graphite particles, a coupling agent, and a wax have a composition shown in the table below in a stirring mixer ("5XDMV-rr type" manufactured by Dalton). The mixture was stirred and mixed to obtain a mixture. A slurry varnish was obtained by mixing 100 parts by mass of this mixture and 70 parts by mass of methyl ethyl ketone. This varnish was applied to a carrier material having a thickness of 75 μm (a film manufactured by Toray Film Processing Co., Ltd.) and then dried by heating at 150 ° C. for 10 minutes. Thereby, a sheet-like conductive material was formed on the carrier material.

  The measurement results of the disk flow of the conductive molding material obtained in each example are shown in the following table.

The details of the raw materials used are as follows. Moreover, the mixture ratio in the table | surface of a postscript is a ratio at the time of converting all the components into solid content.
Epoxy resin A: cresol novolac type epoxy resin (“EOCN-1020-75” manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 199, melting point 75 ° C.).
Epoxy resin B: Naphthalene type epoxy resin (“HP-4700” manufactured by DIC, epoxy equivalent 165, melting point 90 ° C.).
Phenol-based curing agent: novolak type phenol resin (“PSM6200” manufactured by Gunei Chemical Industry Co., Ltd., OH equivalent 105).
Curing accelerator: triphenylphosphine (“TPP” manufactured by Hokuko Chemical Co., Ltd.).
Graphite particles A: natural graphite particles having an average particle diameter of 50 μm.
Graphite particles B: artificial graphite particles having an average particle diameter of 50 μm.
Coupling agent: Epoxy silane (“A187” manufactured by Nippon Unicar Co., Ltd.).
Wax A: natural carnauba wax ("H1-100" manufactured by Dainichi Chemical Co., Ltd., melting point 83 ° C).
Wax B: bisamide montanate (“J-900” manufactured by Dainichi Chemical Industry Co., Ltd., melting point: 123 ° C.)

(Preparation of electrically insulating molding material)
In Examples 1 to 5 and 7 to 11, an epoxy resin, a phenol-based curing agent, a curing accelerator, and silica have compositions shown in the table below in a stirring mixer ("5XDMV-rr type" manufactured by Dalton). The mixture obtained was stirred and mixed, and the resulting mixture was pulverized to a particle size of 500 μm or less with a granulator. As a result, a powdery electrically insulating molding material was obtained.

  In Example 6, an epoxy resin, a phenolic curing agent, a curing accelerator, and silica were mixed in a stirring mixer ("5XDMV-rr type" manufactured by Dalton) so as to have the composition shown in the table below. Further, 70 parts of methyl ethyl ketone as a solvent was mixed and diluted to obtain a slurry varnish. This varnish was applied to a carrier material having a thickness of 75 μm (a film manufactured by Toray Film Processing Co., Ltd.) and then dried by heating at 150 ° C. for 10 minutes. Thus, a sheet-like electrically insulating molding material was formed on the carrier material. Formed.

  The measurement results of the disk flow of the electrically insulating molding material obtained in each example are shown in the following table.

The details of the raw materials used are as follows. Moreover, the mixture ratio in the table | surface of a postscript is a ratio at the time of converting all the components into solid content.
Epoxy resin: Cresol novolac type epoxy resin (“EOCN-1020-75” manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 199, melting point 75 ° C.).
Phenol-based curing agent: novolak type phenol resin (“PSM6200” manufactured by Gunei Chemical Industry Co., Ltd., OH equivalent 105).
Curing accelerator: triphenylphosphine (“TPP” manufactured by Hokuko Chemical Co., Ltd.).
Fused silica: (“FB820” manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 25 μm).
Crystalline silica: (“MCC-4” manufactured by Tatsumori Co., Ltd., average particle size 11 μm).

(Molding)
The conductive molding material and the electrically insulating molding material were placed in a compression mold, and then the conductive molding material and the electrically insulating molding material were simultaneously compression molded in the compression molding mold. In this case, the mold temperature was set to 170 ° C., the molding pressure was set to 35.3 MPa, and the molding time was set to 2 minutes. As a result, a separator having the structure shown in FIGS. 4 and 5 was obtained.

[Measurement of linear expansion coefficient]
A sample was cut out from each of the conductive portion and the insulating portion of the separator in each example. Each sample was heated from 50 ° C. to 100 ° C. at a rate of temperature increase of 10 ° C. per minute using a Seiko Instruments TMA (model SS7100), and the average linear expansion coefficient was measured. The results are shown in the table below.

[Initial interface strength]
By using the conductive molding material and the electrically insulating molding material obtained in each example and compression molding under the same conditions as the separator molding, a cured product of the conductive molding material and a cured product of the electrical insulating molding material. And a test piece bonded to each other was obtained. The dimension of this test piece is 10 mm × 80 mm × 4 mm, and an interface between the cured product of the conductive molding material and the cured product of the electrically insulating molding material exists in the center.

  The interfacial fracture strength between the two kinds of cured products in this test piece was measured under the conditions of a distance between fulcrums of 64 mm and a crosshead speed of 2 mm / min. The results are shown in the table below.

[Thermal shock resistance]
Using the conductive molding material and the electrically insulating molding material obtained in each Example, a test piece was prepared in the same manner as in the case of the “initial interface strength”.

  This test piece was subjected to 1000 cycles of heat treatment in which exposure to a temperature atmosphere of minus 50 ° C. for 30 minutes and exposure to a temperature atmosphere of 150 ° C. for 30 minutes was one cycle. Subsequently, the interface fracture strength of the test piece was measured by the same method as in the case of the “initial interface strength”. The results are shown in the table below.

[Mixed area width]
Using the conductive molding material and the electrically insulating molding material obtained in each Example, a test piece was prepared in the same manner as in the case of the “initial interface strength”.
The maximum width of the region in which the conductive molding material and the electrically insulating molding material were mixed in the interface region between the conductive portion and the insulating portion of the obtained test piece was measured. The results are shown in the table below.

[Insulation failure evaluation]
In each example, 10 separators were produced under the same conditions. The electrical resistance value between two adjacent conductive parts in each separator was measured using a digital multimeter (model DT-110) manufactured by Hozan Co., Ltd. As a result, the case where the measuring device was 100 kΩ or less was determined to be defective. The table below shows the number of defects with respect to the number of separator samples (10).

[Evaluation of conductive part erosion]
In each example, 10 separators were produced under the same conditions. The conductive part of each separator was observed, and the case where the penetration of an insulating material having a depth of 1 mm or more was confirmed to be defective in the conductive part. The table below shows the number of defects with respect to the number of separator samples (10).

DESCRIPTION OF SYMBOLS 1 Separator 2 Conductive part 3 Insulating part 4 Center part 5 Outer peripheral part 6 Second insulating part 7 Compression molding die 8 Conductive molding material 9 Electrical insulating molding material 10 Groove

Claims (5)

A fuel cell separator comprising a central portion provided with a gas distribution groove and an outer peripheral portion surrounding the central portion is a method of manufacturing by a compression molding method,
Preparing an electrically conductive molding material containing an epoxy resin and a phenolic curing agent, and an electrically insulating molding material containing an epoxy resin and a phenolic curing agent,
The equivalent value of the phenolic curing agent with respect to 1 equivalent of the epoxy resin in the conductive molding material is less than 1, and the equivalent of the phenolic curing agent with respect to 1 equivalent of the epoxy resin in the electrically insulating molding material. Is greater than 1 or
The value of the equivalent of the phenolic curing agent with respect to 1 equivalent of the epoxy resin in the conductive molding material is larger than 1, and the phenolic curing agent with respect to 1 equivalent of the epoxy resin in the electrically insulating molding material. The equivalent value is less than 1,
In the compression mold, said conductive molding material as the said electrically insulating molding material is arranged, the conductive molding material and said electrically insulating molding material, compression molding simultaneously within the compression mold The central portion of the fuel cell separator is composed of an insulating portion formed of the electrically insulating molding material and a plurality of conductive portions formed of the conductive molding material and divided by the insulating portion. A method for producing a fuel cell separator. The manufacturing method of the separator for fuel cells of Claim 1 which comprises the said outer peripheral part with the 2nd insulation part formed from the said electrically insulating molding material. The conductive molding material and the electrically insulating molding material are both in powder form, and the value of the disk flow of the conductive molding material is smaller than the value of the disk flow of the electrically insulating molding material. 3. The method for producing a fuel cell separator according to claim 1, wherein the difference in the disk flow values is in the range of greater than 0 mm and not greater than 10 mm. The method for producing a fuel cell separator according to claim 1, wherein at least one of the electrically insulating molding material and the conductive molding material is in a sheet form. The method for producing a fuel cell separator according to any one of claims 1 to 4 , wherein a value of a ratio of a linear expansion coefficient of the insulating portion to the conductive portion is within a range of 1/5 to 5.