JP6218065B2 - Fuel cell separator and method for producing the same - Google Patents

Description

  The present invention relates to a fuel cell parator applied to a fuel cell and a method for manufacturing the same.

  In general, a fuel cell is composed of a cell stack composed of several tens to several hundreds of unit cells stacked in series. For this reason, the fuel cell can generate an electromotive force. 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 polymer electrolyte fuel cell is configured, for example, by 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. 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.

  Insulation sealing is applied between the two fuel cell separators constituting one unit cell so that the fuel cell separators do not directly contact each other. For this reason, the short circuit in a unit cell is prevented. As a method of insulating sealing, for example, in Patent Document 1, when a unit cell is configured by combining a fuel cell separator and a membrane-electrode composite, a rubber material, a thermoplastic resin is provided between two fuel cell separators. It is disclosed that an insulating seal member is formed by injecting an insulating seal member such as the above. In this case, the insulating seal portion electrically insulates the two fuel cell separators.

  However, in the method described in Patent Document 1, it is necessary to add a step of forming an insulating seal portion during a step of forming a unit cell by combining a fuel cell separator and a membrane-electrode assembly. Moreover, when a cell stack is formed by stacking a plurality of unit cells, it is necessary to form an insulating seal portion in each unit cell. For this reason, in constructing the unit cell and the cell stack, a great number of man-hours are required for the insulation sealing, resulting in a decrease in the production efficiency of the fuel cell.

  Patent Document 2 discloses that a polyol vulcanizable fluororubber, a non-conductive reinforcing agent, a polyol vulcanizing agent, a quaternary onium salt vulcanizing agent, and basic magnesium / aluminum are provided on the periphery of a resin-mixed carbon separator. It is disclosed that an insulating film is formed by applying a fluororubber solution containing a hydroxy carbonate hydrate acid acceptor by screen printing and vulcanizing by heating.

  However, since this method includes a step of performing coating by a screen printing method, it requires troublesome work, and this leads to a decrease in production efficiency of the fuel cell separator.

JP2012-54118A JP-A-2005-123108

  The present invention has been made in view of the above-described reasons, and provides a fuel cell separator that can perform insulation sealing between fuel cell separators without requiring much labor, and a method for manufacturing the same. Is an issue.

The fuel cell separator according to the first aspect of the present invention includes a conductive main body member, and the main body member includes a main surface, a gas flow groove formed in the main surface, and the main surface member. A manifold that opens at a surface, a recess that is formed in the main surface and connects the gas flow groove and the manifold, and the gas flow groove, the manifold, and the recess in the main surface. A separator for a fuel cell comprising a flat surface made of a region where none is formed,
The sheet-like member containing the first thermosetting resin composition in a semi-cured state is further cured on the flat surface, further comprising an insulating seal layer laminated on the flat surface. It was formed by this.

  The separator for a fuel cell according to a second aspect of the present invention further includes a bridge portion that covers the opening of the recess on the main surface in the first aspect, and the bridge portion is a cured thermosetting resin. It is characterized by comprising.

  The fuel cell separator according to a third aspect of the present invention is characterized in that, in the second aspect, the bridge portion is connected to and integrated with the insulating seal layer.

In the fuel cell separator according to the fourth aspect of the present invention, in any one of the first to third aspects, the first thermosetting resin composition contains an epoxy resin and a phenolic curing agent,
The main body member is composed of a cured product of a second thermosetting resin composition containing an epoxy resin, a phenolic curing agent, and a conductive material,
The equivalent value of the phenolic curing agent to 1 equivalent of the epoxy resin in the first thermosetting resin composition is less than 1, and the epoxy resin 1 in the second thermosetting resin composition. The equivalent value of the phenolic curing agent to the equivalent is greater than 1, or
The equivalent value of the phenol-based curing agent with respect to 1 equivalent of the epoxy resin in the first thermosetting resin composition is greater than 1, and the epoxy resin 1 in the second thermosetting resin composition. The equivalent value of the phenolic curing agent with respect to the equivalent is less than 1.

  In the fuel cell separator according to a fifth aspect of the present invention, in any one of the first to fourth aspects, the insulating seal layer contains an insulating filler.

  The fuel cell separator according to a sixth aspect of the present invention is characterized in that in any one of the first to fifth aspects, a gasket is further provided.

The method for producing a fuel cell separator according to the seventh aspect of the present invention comprises:
A main surface, a gas flow groove formed in the main surface, a manifold opening in the main surface, and a recess formed in the main surface and connecting the gas flow groove and the manifold And a step of preparing a main body member provided with the gas flow groove on the main surface, the manifold, and a flat surface on which the recess is not formed;
On the flat surface of the main body member, containing a semi-cured thermosetting resin composition, a step of stacking a sheet-like member; and by heating and pressing the main body member and the sheet-like member, The method includes a step of forming an insulating seal layer to be laminated on the flat surface.

  When the fuel cell separator according to the present invention is used, it is possible to perform insulation sealing between the fuel cell separators without requiring much labor.

It is a top view by the side of the 1st main surface of the separator for fuel cells which concerns on one Embodiment of this invention. It is a top view by the side of the 2nd main surface of the separator for fuel cells which concerns on this embodiment. It is a top view by the side of the 1st main surface of the main-body member in the separator for fuel cells which concerns on this embodiment. It is a disassembled perspective view which shows a unit cell provided with the separator for fuel cells which concerns on this embodiment. It is a one part schematic sectional drawing which shows a unit cell provided with the separator for fuel cells which concerns on this embodiment.

  Embodiments of the invention will be described below.

  A fuel cell separator 1 according to the present embodiment (hereinafter referred to as separator 1) is used to partition unit cells in a fuel cell. The separator 1 separates the fuel, the oxidant, and the cooling water so as not to be mixed in the fuel cell, transmits the electric energy generated by the fuel cell to the outside, and dissipates the heat generated in the fuel cell to the outside.

  The separator 1 includes a main body member 2 having conductivity and an insulating seal layer 31. The main body member 2 includes a main surface 21, a gas distribution groove 23 formed on the main surface 21, a manifold 24 opened on the main surface 21, and a gas distribution groove formed on the main surface 21. 23 and a recess 25 that connects the manifold 24. Further, the main body member 2 includes a flat surface 26 formed of a region where none of the gas flow groove 23, the manifold 24, and the recess 25 is formed in the main surface 21. The insulating seal layer 31 is laminated on the flat surface 26. The insulating seal layer 31 is composed of a thermosetting resin cured product.

  In this embodiment, when constituting the unit cell of the fuel cell, when the two separators 1 are stacked, the insulating seal layer 31 having electrical insulation is interposed between the two main body members 2 having conductivity. . For this reason, even if the process for insulation sealing is not added in the process which comprises a unit cell, the insulation sealing between the separators 1 in one unit cell is attained.

  It is preferable that the separator 1 according to the present embodiment further includes a bridge portion 32 that covers the opening of the recess 25 on the main surface 21, and the bridge portion 32 is made of a thermosetting resin cured product. In this case, the bridge portion 32 suppresses gas leakage from the recess 25. For this reason, it becomes difficult for the fuel gas and the oxidant gas to be mixed in the unit cell.

  In the present embodiment, it is preferable that the bridge portion 32 is connected to and integrated with the insulating seal layer 31. In this case, when the insulating seal layer 31 is provided on the main body member 2, the bridge portion 32 is also provided at the same time.

  In the present embodiment, the insulating seal layer 31 is formed by curing the sheet-like member containing the first thermosetting resin composition in a semi-cured state on the flat surface 26. In this case, the insulating seal layer 31 is easily formed.

  In this embodiment, the insulating seal layer 31 is composed of a cured product of a first thermosetting resin composition containing an epoxy resin and a phenolic curing agent, and the main body member 2 is composed of an epoxy resin, a phenolic curing agent, And a cured product of the second thermosetting resin composition containing a conductive material.

  Furthermore, the value of the equivalent of the phenolic curing agent relative to 1 equivalent of the epoxy resin in the first thermosetting resin composition is less than 1, and the phenol relative to 1 equivalent of the epoxy resin in the second thermosetting resin composition. It is preferred that the equivalent value of the system curing agent is greater than 1. In this case, the unreacted epoxy group remaining on the surface of the insulating seal layer 31 and the unreacted hydroxyl group remaining on the surface of the main body member 2 are likely to react with each other. Improved adhesion.

  The value of the equivalent of the phenolic curing agent relative to 1 equivalent of epoxy resin in the first thermosetting resin composition is greater than 1, and the phenolic curing relative to 1 equivalent of epoxy resin in the second thermosetting resin composition It is also preferable that the equivalent value of the agent is less than 1. In this case, the unreacted hydroxyl group remaining on the surface of the insulating seal layer 31 and the unreacted epoxy group remaining on the surface of the main body member 2 are likely to react. For this reason, the insulating seal layer 31 and the main body member 2 Improved adhesion.

  In this embodiment, it is preferable that the insulating seal layer 31 contains an insulating filler. In this case, the insulating filler can improve the electrical insulation and strength of the insulating seal layer 31.

  In the present embodiment, it is preferable that the separator 1 further includes a gasket 4. In this case, the gasket 4 can suppress leakage of gas flowing through the groove 23. Thereby, the leakage of the gas from the unit cell is suppressed.

  The manufacturing method of the separator 1 which concerns on this embodiment is the process of preparing the main body member 2, The process of stacking | stacking the sheet-like member containing the thermosetting resin composition of a semi-hardened state on the flat surface 26 of the main body member 2 It is preferable to include a step of forming the insulating seal layer 31 to be laminated on the flat surface 26 by heating and pressing the main body member 2 and the sheet-like member. In this case, the separator 1 according to this embodiment including the main body member 2 and the insulating seal layer 31 is easily formed.

  Hereinafter, this embodiment will be described in more detail.

  The separator 1 according to the present embodiment includes a main body member 2 having conductivity and an insulating seal layer 31 having electrical insulation. The main body member 2 has a flat plate shape and includes a main surface 21 and a second main surface 22 located on the opposite side of the main surface 21. The insulating seal layer 31 is laminated on the main surface 21 of the main body member 2.

  A separator 1 according to this embodiment is shown in FIGS. FIG. 1 is a plan view of the separator 1 on the main surface 21 side, and FIG. 2 is a plan view of the separator 1 on the second main surface 22 side. FIG. 3 is a plan view of the main body member on the main surface 21 side.

  In the present embodiment, a gas flow groove 23 is formed on the main surface 21 of the main body member 2. The main surface 21 includes a region where the groove 23 is formed (hereinafter also referred to as a central region 27) and a region surrounding the central region 27 where the groove 23 is not formed (hereinafter also referred to as an outer peripheral region 28). . The groove 23 is formed over the entire central region 27. In the present embodiment, a hole (manifold) 24 is formed in the main body member 2. The manifold 24 penetrates the main body member 2 and opens at the outer peripheral region 28 of the main surface 21. 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.

  Furthermore, in the outer peripheral region 28 of the main surface 21, a recess 25 (first recess 251) that communicates the groove 23 and the first manifold 241, and a recess that communicates the groove 23 and the second manifold 242. A location 25 (second recess 252) is formed. Accordingly, the groove 23 in the 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 present embodiment, a region where the manifold 24 and the recess 25 are not formed in the outer peripheral region 28 is the flat surface 26.

  A groove 29 for circulating the refrigerant is formed on the second main surface 22 of the main body member 2. The groove 29 communicates with the fifth manifold 245 and the sixth manifold 246 and does not communicate with the first to fourth manifolds 241 to 244.

  In the present embodiment, the seal member 3 is laminated on the main surface 21 of the main body member 2. The seal member 3 includes an insulating seal layer 31 and a bridge portion 32. In the seal member 3, the insulating seal layer 31 and the bridge portion 32 are integrally connected. The insulating seal layer 31 is laminated on the flat surface 26. Further, a bridge portion 32 that covers the opening of the recess 25 is disposed on the main surface 21 of the main body member 2. The seal member 3 is formed with a hole 33 that passes through a position corresponding to the central region 27. Further, the seal member 3 is formed with first to sixth holes 341 to 346 corresponding to the first to sixth manifolds 241 to 246, respectively.

  In the present embodiment, the gasket 4 is provided on the insulating seal layer 31 and the bridge portion 32 (that is, on the seal member 3). The gasket 4 surrounds the hole 33 and the first to sixth holes 341 to 346 on the seal member 3.

  In this embodiment, the main body member 21 is comprised from the hardened | cured material of the 2nd thermosetting resin composition containing a thermosetting resin and an electroconductive material.

  The conductive material is particularly preferably graphite particles. By using the graphite particles, the electrical resistivity of the main body member 2 is reduced, and the conductivity of the main body member 2 is improved. The ratio of the graphite particles in the second thermosetting resin composition is preferably in the range of 60 to 90% by mass with respect to the total solid content in the second thermosetting resin composition. That is, the ratio of the graphite particles in the main body member 2 is preferably in the range of 60 to 90% by mass. When the ratio of the graphite particles is 60% by mass or more, sufficiently excellent conductivity is imparted to the main body member 2, and when the ratio is 90% by mass or less, the second thermosetting resin is provided. Sufficient moldability is imparted to the composition and sufficient gas permeability is imparted to the body member 2. 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, as graphite particles, 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 selected from quiche graphite, expanded graphite and the like are used.

  The graphite particles are preferably purified. In this case, since the contents of ash and ionic impurities in the graphite particles are low, elution of impurities from the main body member 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 size is 10 μm or more, the moldability of the second thermosetting resin composition becomes excellent. 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 main body member 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. At least one resin selected from oxazine resins can be contained. Among these, it is preferable to use at least one resin selected from benzoxazine resin, epoxy resin, and thermosetting phenol resin. In this case, the heat resistance and mechanical strength of the main body member 2 are particularly high.

  When an epoxy resin is used, the epoxy resin is at least one selected from ortho-cresol novolac type epoxy resin, bisphenol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, and phenol aralkyl type epoxy resin having a biphenylene skeleton. It is preferable to contain a resin. 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 second thermosetting resin composition further contains a curing agent for the epoxy resin. 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, 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.

  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 main body member 2 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 Although the resol resin is usually liquid, the softening point of the resol type phenol resin is easily adjusted, and a resol type phenol resin having a melting point of 70 to 90 ° C. can be easily obtained. Thereby, the change of a 2nd thermosetting resin composition decreases, and the handleability at the time of shaping | molding improves. When this melting point is less than 70 ° C., the components are likely to aggregate in the second thermosetting resin composition, and the handleability may be reduced.

  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 second thermosetting resin composition is 0.5 to 3% by mass with respect to the total amount of the thermosetting resin and the curing agent in the second thermosetting resin composition. A range is preferable.

  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 second thermosetting resin composition may further contain an internal release agent. As the internal mold release agent, an appropriate one is used. In particular, this internal mold release agent is compatible with the thermosetting resin and the curing agent in the second thermosetting resin composition at 120 to 190 ° C. It is preferable to have the property of phase separation without any. As such an internal release agent, it is preferable to use at least one 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 second thermosetting resin composition, so that the mold release improving effect is satisfactorily exhibited.

  The amount of the internal release agent used is appropriately set in consideration of the complexity of the shape of the main body member 2, 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 second thermosetting resin composition is preferably in the range of 0.1 to 2.5% by mass. When this ratio is 0.1% by mass or more, sufficient releasability is exhibited at the time of molding the mold, and when this ratio is 2.5% by mass or less, the hydrophilicity of the surface of the main body member 2 due to the internal release agent. 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 2nd thermosetting resin composition may contain additives, such as a coupling agent, as needed. Examples of the coupling agent include silicon-based silane compounds, titanate-based, and aluminum-based coupling agents. In particular, an epoxy run 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 run coupling agent is the range of 0.5-1.5 mass% with respect to the whole solid content of a 2nd thermosetting resin composition. In this range, bleeding of the coupling agent on the surface of the main body member 2 is sufficiently suppressed.

  The second thermosetting resin composition may further contain short fibers such as carbon fibers and metal fibers. Further, the second thermosetting resin composition may contain various additives within a range in which a function necessary for the main body member 2 is ensured.

  The second thermosetting resin composition may contain a solvent. In particular, when the thin body member 2 is produced, the second thermosetting resin composition contains a solvent, so that the second thermosetting resin composition is liquid (varnish and slurry). May be prepared). 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.

  It is preferable that the content of ionic impurities in the main body member 2 is small, and it is particularly preferable that the sodium content in the main body member 2 is 5 mass ppm or less and the chlorine content is 5 mass ppm or less. For this purpose, the content of ionic impurities in the second thermosetting resin composition is preferably low. The content of ionic impurities is derived based on the amount of ionic impurities in the extraction water of the object. The extracted water can be obtained by putting the object into ion-exchanged water at a rate of 100 ml of ion-exchanged water with respect to 10 g of the object and treating it at 90 ° C for 50 hours. Ionic impurities in the extracted water are evaluated by ion chromatography. Based on the amount of ionic impurities in the extracted water, the amount of ionic impurities in the object is derived in terms of a mass ratio with respect to the object.

The second thermosetting resin composition is preferably prepared such that the TOC (total organic carbon) of the main body member 2 is 100 ppm or less. When the TOC of the main body member 2 is 100 ppm or less, deterioration of the characteristics of the fuel cell is further suppressed. The TOC is a numerical value measured using an aqueous solution after the main body member 2 is charged into ion-exchanged water and treated at 90 ° C. for 50 hours at a ratio of 100 ml of ion-exchanged water with respect to 10 g of mass of the main body member 2 is there. The TOC is measured by, for example, a total organic carbon analyzer “TOC-50” manufactured by Shimadzu Corporation based on JIS K0102. In the measurement, the CO ₂ concentration generated by burning the sample is measured by a non-dispersive infrared gas analysis method, and the carbon concentration in the sample is quantified. By measuring the carbon concentration, the organic substance concentration is indirectly measured, and the inorganic carbon (IC) and total carbon (TC) in the sample are measured. From the difference between the total carbon and inorganic carbon (TC-IC), the total organic Carbon (TOC) is measured. As for the TOC value, a high-purity component is selected as each component constituting the second thermosetting resin composition, the equivalent ratio of the resin is further adjusted, or a post-curing treatment is performed at the time of molding. And reduced.

  The second thermosetting resin composition 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.

  In this embodiment, a molded body is obtained by molding the second thermosetting resin composition, and the body member 2 is obtained by subjecting the molded body to surface treatment. In addition, the main body member 2 may be obtained without surface treatment by shape | molding a 2nd thermosetting resin composition.

  The method for molding the second thermosetting resin composition is selected from appropriate molding methods such as an injection molding method, a transfer molding method, a compression molding method, and an extrusion molding method. In particular, when the compression molding method is employed, the dimensional accuracy of the main body member 2 and the mechanical strength of the main body member 2 are improved.

  When the compression molding method is adopted, it is preferable that the second thermosetting resin composition is molded by this mold in a state where the mold is disposed under a reduced pressure condition or a vacuum condition. In this case, the density variation of the molded body is reduced and the thickness accuracy of the molded body is increased. In particular, the degree of vacuum around the mold 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 second thermosetting resin composition, the molding thickness, etc., for example, the heating temperature is set in the range of 120 to 190 ° C. and the compression pressure is in the range of 1 to 40 MPa. It is preferred that The molding time is preferably set in the range of 15 seconds to 600 seconds.

  After the compression molding, the mold is cooled, and then the molded body is taken out from the mold. This molded body 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.

  In the present embodiment, the molded body is subjected to blasting such as wet blasting. Thereby, the skin layer on the surface of the molded body is removed and the roughness of the surface of the molded body is adjusted. The arithmetic average height Ra (JIS B0601: 2001) of the surface of the molded body is preferably adjusted to a range of 0.4 to 1.6 μm.

  The material of the abrasive (abrasive grain) used for the wet blast treatment is not particularly limited, and examples thereof include alumina, silicon carbide, zirconia, glass, nylon, and stainless steel. The average particle size of the abrasive is appropriately set, but is preferably in the range of 3 to 200 μm, preferably in the range of 3 to 60 μm, and preferably in the range of 6 to 45 μm. A range of ˜40 μm is more preferable. The average particle diameter of the abrasive is the particle diameter (d50) at the 50% cumulative height.

  It is also preferred that the molded body is subjected to a hydrophilic treatment after the wet blast treatment. It is also preferable that after the wet blasting treatment, the molded body is subjected to a hydrophilization treatment after being subjected to a cleaning treatment, or after the cleaning treatment is further subjected to a drying treatment. In the washing process, for example, the molded body is washed with ion exchange water or the like. In the drying process, the molded body is preferably air-dried by air blow or the like. In the drying process, the molded product is allowed to stand in a desiccator containing a desiccant such as silica gel, the molded product is allowed to stand in a dryer having a temperature of room temperature or higher (for example, 50 ° C.), and vacuum drying. A method of removing moisture from the molded body using a machine may be employed. By this drying treatment, the molded body 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 23. As a result, higher hydrophilicity is imparted to the inner surface of the gas flow groove 23. The hydrophilic treatment may be performed over the entire surface of the molded body where the grooves 23 are formed.

The hydrophilic treatment is not particularly limited as long as it is a treatment capable of improving the hydrophilicity of the inner surface of the gas flow groove 23. The hydrophilization treatment includes, for example, plasma treatment for exposing the molded body to plasma, ozone gas treatment for exposing the molded body to ozone gas, SO ₃ treatment for exposing the molded body to SO ₃ , and fluorine for exposing the molded body to a gas containing fluorine. One or more types are selected from the treatment, the flame treatment in which a gas containing a modifier compound containing a silicon compound or an aluminum compound is burned, and the ozone water treatment in which ozone water is brought into contact with the molded body. In particular, it is preferable to employ plasma treatment.

  In this embodiment, the sealing member 3 is comprised from the hardened | cured material of the 1st thermosetting resin composition containing a thermosetting resin. That is, the insulating seal layer 31 and the bridge part 32 are comprised from the hardened | cured material of a 1st thermosetting resin composition.

  The thermosetting resin contained in the first thermosetting resin composition is, for example, epoxy resin, thermosetting phenol resin, vinyl ester resin, polyimide resin, unsaturated polyester resin, diallyl phthalate resin, polyester resin, urea resin, It can contain at least one resin selected from melamine resin, silicone resin, vinyl ester resin, and benzoxazine resin. Among these, it is preferable to use at least one resin selected from benzoxazine resin, epoxy resin, and thermosetting phenol resin. In this case, the heat resistance and mechanical strength of the seal member 3 are particularly high.

  When an epoxy resin is used, the epoxy resin is at least one selected from ortho-cresol novolac type epoxy resin, bisphenol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, and phenol aralkyl type epoxy resin 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 first thermosetting resin composition 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, 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.

  When the first thermosetting resin composition contains an epoxy resin and a phenolic curing agent, it is preferable that the second thermosetting resin composition contains an epoxy resin and a phenol resin. In this case, the adhesion between the main body member 2 and the seal member 3 is increased.

  In particular, the phenolic curing agent equivalent value relative to 1 equivalent of epoxy resin in the first thermosetting resin composition is less than 1, and phenol relative to 1 equivalent of epoxy resin in the second thermosetting resin composition. It is preferred that the equivalent value of the system curing agent is greater than 1. In this case, the unreacted epoxy group remaining on the surface of the insulating seal layer 31 and the unreacted hydroxyl group remaining on the surface of the main body member 2 are likely to react with each other. Improved adhesion. In particular, the equivalent value of the phenolic curing agent with respect to 1 equivalent of epoxy resin in the first thermosetting resin composition is in the range of 1.05 to 1.20, and in the second thermosetting resin composition. It is preferable that the equivalent value of the phenolic curing agent with respect to 1 equivalent of the epoxy resin is in the range of 0.8 to 0.95.

  The value of the equivalent of the phenolic curing agent relative to 1 equivalent of epoxy resin in the first thermosetting resin composition is greater than 1, and the phenolic curing relative to 1 equivalent of epoxy resin in the second thermosetting resin composition It is also preferable that the equivalent value of the agent is less than 1. In this case, the unreacted hydroxyl group remaining on the surface of the insulating seal layer 31 and the unreacted epoxy group remaining on the surface of the main body member 2 are likely to react. For this reason, the insulating seal layer 31 and the main body member 2 Improved adhesion. In particular, the equivalent value of the phenolic curing agent with respect to 1 equivalent of the epoxy resin in the first thermosetting resin composition is in the range of 0.8 to 0.95, and in the second thermosetting resin composition. It is preferable that the equivalent value of the phenolic curing agent with respect to 1 equivalent of the epoxy resin is in the range of 1.05-1.20.

  The insulating seal layer 31 preferably contains an insulating filler, and for that purpose, the first thermosetting resin composition preferably contains an insulating filler. The insulating filler contains, for example, at least one filler selected from the group consisting of aluminum oxide, aluminum nitride, silicon oxide, silicon nitride, and boron nitride.

  The ratio of the insulating filler in the first thermosetting resin composition is not particularly limited, but is adjusted so that the ratio of the insulating filler in the insulating seal layer 31 is in the range of 60 to 93% by mass. It is preferable.

  The first thermosetting resin composition may further contain a catalyst, a coupling agent, an internal mold release agent, a solvent, other additives, and the like as necessary.

  In the present embodiment, the seal member 3 is formed by curing the sheet-like member containing the first thermosetting resin composition in a semi-cured state on the main surface 21 of the main body member 2. That is, the insulating seal layer 31 is formed by curing the portion of the sheet-like member that overlaps the flat surface 26 on the flat surface 26, and the portion of the sheet-like member that covers the opening of the recess 25 is cured. Part 32 is formed.

  The sheet-like member can be obtained, for example, by forming the first thermosetting resin composition into a sheet shape and drying by heating. In addition, the sheet-like member may be obtained by impregnating the first thermosetting resin composition into a base material such as a glass woven fabric, a glass nonwoven fabric, or paper and then drying by heating.

  In forming the seal member 3, for example, the main body member 2 and the sheet-like member are heated and pressed in a state where the sheet-like member is stacked on the main surface 21 of the main body member 2. In this case, the seal member 3 is formed by the sheet-like member being cured and being in close contact with the main body member 2. As a result, the bridge portion 32 and the insulating seal layer 31 are formed simultaneously and easily.

  In forming the seal member 3, a simultaneous multi-stage press technique may be employed. That is, for example, a plurality of laminates composed of the main body member 2 and the sheet member may be laminated via a heat-resistant release film, and then these may be heated and pressed. In this case, a plurality of separators 1 including the main body member 2 and the seal member 3 can be manufactured simultaneously.

  The thickness of the seal member 3, that is, the thickness of the insulating seal layer 31 and the bridge portion 32 is set as appropriate, but is preferably in the range of 0.05 to 0.3 mm. If this thickness is 0.05 mm or more, especially when the seal member 3 is formed from a sheet-like member, the handleability of the sheet-like member is improved. Further, when the thickness is 0.3 mm or less, it is easy to make the sheet-like member uniform, and therefore, for example, it is not necessary to superimpose a plurality of thin sheet-like members.

  The gasket 4 is, for example, natural rubber, silicone rubber, SIS copolymer, SBS copolymer, SEBS, ethylene-propylene rubber, ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber (HNBR). ), A rubber material selected from chloroprene rubber, acrylic rubber, fluorine rubber, and the like. This rubber material may contain a tackifier.

  For example, the gasket 4 is provided on the seal member 3 by bonding the preformed gasket 4 to the seal member 3 by being bonded or fused.

  Further, the gasket 4 may be formed by molding a material for forming the gasket 4 on the seal member 3. In this case, for example, the material for forming the gasket 4 on the seal member 3 is applied by a screen printing method or the like, and the material is subsequently cured, so that the gasket 4 may be provided on the seal member 3. . For example, even if an unvulcanized rubber material is applied to a predetermined position on the surface of the sealing member 3 by screen printing or the like, and a coating film of the rubber material is vulcanized, a gasket 4 having a desired shape is formed. Good. In the vulcanization, heating, irradiation with radiation such as an electron beam, or other appropriate vulcanization methods are employed.

  In a state where the main body member 2 and the seal member 3 are set in the mold, an unvulcanized rubber material is injected into a predetermined position on the seal member 3 and the rubber material is heated and vulcanized. Thus, the gasket 4 may be formed on the seal member 3. In this way, when the gasket 4 is formed by molding, molding methods such as compression molding and injection molding can be employed in addition to transfer molding.

  When the gasket 4 is formed by molding, it is preferable that the gasket 4 is further heated. In this case, the curing reaction of the gasket 4 further proceeds, and thereby the elution of impurities from the gasket 4 is suppressed.

  A configuration of a fuel cell including the separator 1 according to the present embodiment will be described.

  FIG. 4 is an exploded perspective view of a unit cell in the fuel cell, and FIG. 5 is a partial cross-sectional view of the unit cell.

  The unit cell is configured by stacking the separator 1 and the membrane-electrode assembly 5. The membrane-electrode assembly 5 includes an oxidant electrode 51 that is a cathode, a fuel electrode 52 that is an anode, and an electrolyte membrane 53.

  In the present embodiment, one unit cell includes a cathode side separator 101 and an anode side separator 102 as the separator 1. In the unit cell, the central region 27 of the main surface 21 of the cathode-side separator 101 overlaps with the oxidizer electrode 51, and the central region 27 of the main surface 21 of the anode-side separator 102 overlaps with the fuel electrode 52.

  The unit cell includes a first manifold 241, a first recess 251, a groove 23, a second recess 252, and an oxidant gas flow path that sequentially passes through the second manifold 242 of the cathode separator 101. A first manifold 241, a first recess 251, a groove 23, a second recess 252, and a fuel gas flow path that sequentially passes through the second manifold 242 are formed.

  Since each of the two separators 1 (the cathode side separator 101 and the anode side separator 102) in the unit cell includes the insulating seal layer 31, the insulating seal layers 31 of the two separators 1 overlap with each other, and the body members 2 are Do not touch directly. For this reason, the short circuit between the separators 1 in a unit cell is prevented.

  When two unit cells are stacked, the second main surface 22 of the cathode side separator 101 in one unit cell and the second main surface 22 of the anode side separator 102 in the other unit cell are: Overlaid. Between the cathode-side separator 101 and the anode-side separator 102, a refrigerant flow path including a refrigerant flow groove 29 is formed. For example, water is used as the refrigerant. The refrigerant flow path communicates with the refrigerant circulation manifold 24 (the fifth manifold 245 and the sixth manifold 246) of the separator 1.

  Further, in this unit cell, the bridge portion 32 covers each opening of the plurality of recesses 25. For this reason, the bridge part 32 suppresses the leakage of the gas from the recess 25. For this reason, leakage of the oxidant gas to the fuel electrode 52 through the recess 25 is suppressed, and leakage of the fuel gas to the oxidant electrode 51 through the recess 25 is suppressed. In the present embodiment, leakage of the oxidant gas to the fuel electrode 52 and leakage of the fuel gas to the oxidant electrode 51 are suppressed with high reliability by a simple configuration in which the bridge portion 32 is provided.

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

[Examples 1 to 5]
For each example and comparative example, a separator having the configuration shown in FIGS. 1 and 2 was produced as follows.

  In producing the main body member, first, the raw material components shown in the following table are put into a stirring mixer ("5XDMV-rr type" manufactured by Dalton) and stirred and mixed, and the resulting mixture is adjusted to a particle size of 500 µm or less with a granulator. Crushed. This obtained the 2nd thermosetting resin composition.

  The obtained second thermosetting resin composition was compression molded under conditions of a mold temperature of 170 ° C., a molding pressure of 35.3 MPa, and a molding time of 2 minutes.

By this compression molding, a molded body was obtained, and a gas circulation groove, a refrigerant circulation groove, six manifolds, and a recess were formed in the molded body. The dimensions of the molded body are 200 mm × 250 mm in plan view and a thickness of 1.5 mm. The dimensions of the groove for gas circulation and the groove for refrigerant circulation are 0.5 mm wide and 0.5 mm deep, respectively. The opening area is 3.5 cm ² .

  The surface of this molded body is subjected to a blasting process using a slurry containing alumina particles as abrasive grains using a wet blasting apparatus (model PFE-300T / N) manufactured by Macau Corporation, and then washed with ion-exchanged water. Further, it was dried with warm air. Thus, the skin layer was removed from the molded body, and the arithmetic average height Ra (JIS B0601: 2001) of the surface was adjusted to 0.5 μm.

  Subsequently, the molded body was washed with ion-exchanged water and further dried with hot air, and then the molded body was subjected to a remote atmospheric pressure plasma treatment. In the atmospheric pressure plasma treatment, AP-T series manufactured by Sekisui Chemical Co., Ltd. was used as the plasma treatment apparatus. Processing conditions are: processing width: 300 mm, number of plasma units: 1, sample-electrode distance: 3 mm, gas type for plasma generation: nitrogen, oxygen content in gas: 1000 ppm, gas flow rate: 150 L / min, sample transport Speed: 0.25 m / min, processing temperature: 25 ° C. Thereby, the main body member was obtained.

  Moreover, the sealing member provided with an insulation sealing layer and a bridge | bridging part was produced as follows.

  A first thermosetting resin composition was obtained by mixing the raw material components shown in the table below. The first thermosetting resin composition was impregnated into glass cloth (manufactured by Nittobo, product number WEA116E, thickness 0.1 mm), and then semi-cured by heating and drying. Thereby, the sheet-like member provided with the 1st thermosetting resin composition of a semi-hardened state was obtained. In the sheet-like member, holes corresponding to the central region of the main body member and the manifold were formed.

  After a sheet-like member and a heat-resistant release film were stacked on the main surface of the main body member, they were hot pressed under the conditions of a pressure of 10 MPa, a heating time of 170 ° C., and a heating and pressing time of 1 hour. Thereby, the sheet-like member was cured on the main surface of the main body member to form a seal member including the insulating seal layer and the bridge portion, and the seal member was brought into close contact with the main body member. The thickness of the insulating seal layer and the bridge portion is 0.15 mm.

  Next, after applying ethylene-propylene-diene rubber by screen printing around each hole on the seal member, a gasket was formed by heat vulcanization.

  Thereby, the separator provided with a main body member, a sealing member, and a gasket was obtained.

[Measurement of linear expansion coefficient]
A sample was cut out from each of the main body member and the seal member 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 adhesion]
Using the second thermosetting resin composition and the sheet-like member obtained in each Example, the cured product of the second thermosetting resin composition and the sheet-like member were cured under the same conditions as in the separator molding. A test piece bonded to the object was obtained. The planar view size of the cured product of the sheet-like member in this test piece is 4 mm × 4 mm.

  The adhesion strength (shear strength) between the two types of cured products in this test piece was measured using a bonding strength tester (DS100 manufactured by Daisy). The results are shown in Table 1.

[durability]
Using the second thermosetting resin composition and the sheet-like member obtained in each Example, the cured product of the second thermosetting resin composition and the sheet-like member were cured under the same conditions as in the separator molding. A test piece bonded to the object was obtained. The planar view size of the cured product of the sheet-like member in this test piece is 4 mm × 4 mm.

  This test piece was repeatedly subjected to heat treatment 1000 times after being exposed to a 50 ° C. temperature atmosphere for 30 minutes and then exposed to a 150 ° C. temperature atmosphere for 30 minutes. Subsequently, the adhesion strength (shear strength) between the two kinds of cured products in the test piece was measured using a bonding strength tester (DS100 manufactured by Daisy). The results are shown in Table 1.

  In addition, the detail of the component used by the present Example is as follows.

Raw material of second thermosetting resin composition / epoxy resin: Cresol novolac type epoxy resin (“EOCN-1020-75” manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 199, melting point 75 ° C.).
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.).
Natural graphite (“WR50A” manufactured by Chuetsu Graphite Industries Co., Ltd., average particle size 50 μm, ash content 0.05%, sodium ion 4 ppm, chloride ion 2 ppm).
Artificial graphite (“SGP100” manufactured by SEC Carbon Co., Ltd., average particle size 100 μm, ash content 0.05%, sodium ion 3 ppm, chloride ion 1 ppm).
Coupling agent: Epoxy silane (“A187” manufactured by Nippon Unicar Co., Ltd.).
Internal release agent A: natural carnauba wax (“H1-100” manufactured by Dainichi Chemical Co., Ltd., melting point 83 ° C.).
-Internal mold release agent B: Montanic acid bisamide ("J-900" manufactured by Dainichi Chemical Co., Ltd., melting point: 123 ° C)

Raw material of first thermosetting resin composition / epoxy resin: Cresol novolac type epoxy resin (“EOCN-1020-75” manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 199, melting point 75 ° C.).
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.).
Spherical silica: (“MSR04” manufactured by Tatsumori, average particle size 4.1 μm).
Coupling agent: Epoxy silane (“A187” manufactured by Nippon Unicar Co., Ltd.).
・ Solvent: MEK (methyl ethyl ketone)

DESCRIPTION OF SYMBOLS 1 Separator 2 Main body member 21 Main surface 22 Second main surface 23 Groove for gas distribution 24 Manifold 25 Recess 26 Flat surface 31 Insulating seal layer 32 Bridge part

Claims (7)

A main body member having conductivity, the main body member is formed on the main surface, a groove for gas circulation formed on the main surface, a manifold opened on the main surface, and the main surface, A fuel provided with a recess for connecting a gas flow groove and the manifold, and a flat surface formed of a region in the main surface where none of the gas flow groove, the manifold, or the recess is formed. A battery separator,
The sheet-like member containing the first thermosetting resin composition in a semi-cured state is further cured on the flat surface, further comprising an insulating seal layer laminated on the flat surface. Formed by
Further comprising, the bridge portion, fuel cell separator you characterized in that it is composed of a cured thermosetting resin bridge portion covering the opening of said recess on said main surface. A main body member having conductivity, the main body member is formed on the main surface, a groove for gas circulation formed on the main surface, a manifold opened on the main surface, and the main surface, A fuel provided with a recess for connecting a gas flow groove and the manifold, and a flat surface formed of a region in the main surface where none of the gas flow groove, the manifold, or the recess is formed. A battery separator,
The sheet-like member containing the first thermosetting resin composition in a semi-cured state is further cured on the flat surface, further comprising an insulating seal layer laminated on the flat surface. Formed by
The first thermosetting resin composition contains an epoxy resin and a phenolic curing agent,
The main body member is composed of a cured product of a second thermosetting resin composition containing an epoxy resin, a phenolic curing agent, and a conductive material,
The equivalent value of the phenolic curing agent to 1 equivalent of the epoxy resin in the first thermosetting resin composition is less than 1, and the epoxy resin 1 in the second thermosetting resin composition. The equivalent value of the phenolic curing agent to the equivalent is greater than 1, or
The equivalent value of the phenol-based curing agent with respect to 1 equivalent of the epoxy resin in the first thermosetting resin composition is greater than 1, and the epoxy resin 1 in the second thermosetting resin composition. fuel cell separator you wherein the equivalent value of the phenolic curing agent to equivalents is less than 1. The fuel cell separator according to claim 2, further comprising a bridge portion that covers the opening of the recess on the main surface, and the bridge portion is made of a thermosetting resin cured product. 4. The fuel cell separator according to claim 1, wherein the bridge portion is connected and integrated with the insulating seal layer. 5. The fuel cell separator according to any one of claims 1 to 4, wherein the insulating seal layer contains an insulating filler. The fuel cell separator according to any one of claims 1 to 5, further comprising a gasket. Main surface,
A gas distribution groove formed on the main surface;
A manifold opening at the main surface;
A recess formed in the main surface and connecting the gas flow groove and the manifold;
Preparing a main body member comprising the gas flow groove on the main surface, the manifold, and a flat surface on which the recess is not formed;
On the flat surface of the main body member, containing a semi-cured thermosetting resin composition, a step of stacking a sheet-like member; and by heating and pressing the main body member and the sheet-like member, The manufacturing method of the separator for fuel cells characterized by including the process of forming the insulating seal layer laminated | stacked on the said flat surface.