JP5849229B2 - Fuel cell separator and fuel cell - Google Patents

Description

  The present invention relates to a fuel cell separator and a fuel cell.

  In general, in a fuel cell, an electromotive force is generated when a plurality of single cells are overlapped in series to form a cell stack. Fuel cells are classified into several types depending on the type of electrolyte. In recent years, attention has been paid to a solid polymer fuel cell having a solid polymer electrolyte membrane as an electrolyte as a high-power fuel cell.

  A single cell of a polymer electrolyte fuel cell is configured, for example, by stacking a fuel cell separator, a gasket, and a membrane-electrode composite (see FIG. 1). A separator for a fuel cell is formed with a groove for flowing a fluid such as fuel, oxidant, and cooling water on one or both sides, and a manifold hole is formed in an outer peripheral portion surrounding the area where the groove is formed. Is formed. Further, a sealing gasket is laminated on the outer peripheral portion of the fuel cell separator as required.

  Among the components constituting such a fuel cell, the fuel cell separator has a unique shape in which fine grooves and manifold holes are formed as described above. The fuel cell separator has a function of separating the fuel, oxidant, and cooling water flowing in the fuel cell so as not to mix, and transmits electric energy generated by the fuel cell to the outside or heat generated by the fuel cell. It plays an important role of radiating heat to the outside.

  The fuel cell separator is formed of, for example, a metal plate or a molding material containing graphite particles and a resin component. Among these, the fuel cell separator formed from a metal plate has the advantages of good production efficiency and high conductivity.

  However, a fuel cell separator formed of a metal plate has a problem that it is easily corroded. In particular, when cooling water flows through the manifold hole of the fuel cell separator, corrosion tends to occur from the periphery of the manifold hole, and there is a risk that the cooling water will eventually leak from the fuel cell.

  Various methods for improving the corrosion resistance of fuel cell separators formed from metal plates have been studied, but it has been difficult to sufficiently improve the corrosion resistance of fuel cell separators, or improved corrosion resistance. It took a lot of time and effort. For example, Patent Document 1 contains 5 mass% or less of B as a base material, and TiB boride particles are dispersed and deposited on the entire base material, and a part of the passive film formed on the base material surface. A titanium-based material for a fuel cell separator that is exposed on the surface and constitutes an electrical conduction path is disclosed. However, even with the technique described in Patent Document 1, it has been difficult to sufficiently improve the corrosion resistance of the fuel cell separator.

JP 2004-273370 A

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a fuel cell separator that is made of a metal member and has high corrosion resistance.

  The separator for a fuel cell according to the present invention includes a metal first member in which a groove for allowing fluid to flow is formed, a manifold hole communicating with the groove, and a thermosetting resin and graphite. It is comprised with the 2nd member formed from the hardened | cured material of the molding material to contain.

In the present invention, the true density of the graphite is preferably 2.22 g / cm ³ or more, and the content of the graphite in the second member is preferably in the range of 70 to 80% by mass.

  The fuel cell according to the present invention includes the fuel cell separator.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell separator comprised from a metal member and having high corrosion resistance, and a fuel cell provided with this fuel cell separator are obtained.

It is sectional drawing which shows the separator for fuel cells in an example of embodiment of this invention. It is a disassembled perspective view which shows the single cell structure of the fuel cell in an example of embodiment of this invention. It is a perspective view showing a fuel cell in an example of an embodiment of the invention.

  In FIG. 2, an example of the structure of the unit cell of a polymer electrolyte fuel cell provided with the separator 20 is shown. A membrane-electrode assembly (MEA) 5 comprising an electrolyte 4 such as a solid polymer electrolyte membrane and a gas diffusion electrode (fuel electrode 31 and oxidant electrode 32) is interposed between the two separators 20 and 20. Thus, a unit cell (unit cell) is configured. A gasket 12 is interposed between the separator 20 and the electrolyte 4 of the membrane-electrode assembly 5. A battery body (cell stack) is formed by arranging several tens to several hundreds of unit cells.

  The separator 20 is formed with a groove 2 for flowing a fluid such as fuel, oxidant, and cooling water.

  In the present embodiment, the separator 20 has a groove 2 (201) for flowing fuel on one side and an anode side separator 21 having a groove 2 (203) for flowing cooling water on the other side. The cathode side has a groove 2 (202) for flowing an oxidant on one side opposite to the anode separator and a groove 2 (203) for flowing cooling water on the other side. Separator 22 is used. When the anode side separator 21 and the cathode side separator 22 are overlapped, a channel through which cooling water flows is formed between the groove 203 in the anode side separator 21 and the groove 203 in the cathode side separator 22. A gasket may be interposed between the anode side separator 21 and the cathode side separator 22.

  In the outer peripheral portion surrounding the region where the groove 2 is formed, the separator 20 has six manifold holes 13 (two fuel manifold holes 131, two oxidant manifold holes 132, and two cooling manifold holes). 133) is formed. Two fuel manifold holes 131 and 131 are formed, and each fuel manifold hole 131 and 131 communicates with both ends of the groove 2 on the surface of the anode separator 21 that overlaps the fuel electrode 31. Two oxidant manifold holes 132, 132 are also formed, and each oxidant manifold hole 132, 132 communicates with both ends of the groove 2 on the surface overlapping the oxidant electrode 32 of the cathode side separator 22. Two cooling manifold holes 133 are also formed in the outer peripheral portion. Each of the cooling manifold holes 133 and 133 communicates with both ends of the groove 2 through which the cooling water in the separator 20 flows.

  In the present embodiment, as shown in FIG. 1, a straight type groove 2 is formed in the separator 20. Generally, as a groove in the separator, there are a serpentine type groove having a bend and a straight type groove having no bend. Of course, in the separator 20 shown in FIG. 1, a serpentine type groove may be formed in the separator 20.

The thickness of the separator 20 is formed in the range of 0.5-3.0 mm, for example. The width of the groove 2 of the separator 20 is, for example, 1.0 to 1.5 mm, and the depth is, for example, 0.5 to 1.5 mm. The opening area of the manifold hole 13 is formed in the range of 0.5 to 5.0 cm ² , for example.

  The separator 20 includes a first member 61 and a second member 62. The first member 61 is made of metal, and the groove 2 is formed in the first member 61. The second member 62 is formed from a cured product of a molding material containing a thermosetting resin and graphite, and has a frame shape. A manifold hole 13 is formed in the second member 62. The first member 61 is held and fixed inside the second member 62, whereby the groove 2 in the first member 61 communicates with the manifold hole 13 in the second member 62.

  FIG. 1 shows an example of a cross-sectional structure of the separator 20. The first member 61 is made of an appropriate metal such as stainless steel, aluminum, titanium, or various alloys. The first member 61 is obtained, for example, by forming a metal plate into a corrugated plate by bending, press forming, or the like. In this case, the grooves 2 are formed on both surfaces of the first member 61. The first member 61 constitutes a region in the separator where the groove 2 is formed. The thickness of the metal plate constituting the first member 61 is preferably in the range of 0.05 to 0.30 mm.

  The second member 62 is formed from a cured product of a molding material containing a thermosetting resin and graphite particles. The second member 62 has a frame shape, that is, the second member 62 is formed with an opening 63 that matches the first member 61. The second member 62 constitutes an outer peripheral portion surrounding the region where the groove is formed in the separator. The second member 62 has six manifold holes 13 (two fuel manifold holes 131, two oxidant manifold holes 132, and two cooling manifold holes 133).

  By arranging the first member 61 in the opening 63 of the second member 62, the first member 61 and the second member 62 are combined, and thereby the separator 20 is configured. The first member 61 may be fixed to the second member 62 by an appropriate method. For example, after first producing the first member 61, the first member 61 is placed in a compression molding die, and the second member 62 is produced by insert molding using the compression molding die. In this case, the first member 61 and the second member 62 are integrated at the same time as the second member 62 is manufactured, and thereby the first member 61 can be fixed to the second member 62.

  The first member 61 and the second member 62 are separately manufactured, and then the first member 61 is bonded to the second member 62 with an adhesive, and the first member 61 and the first member 61 are bonded with this adhesive. Sealing between the second member 62 and the first member 61 may be fixed to the second member 62. Examples of such an adhesive include an olefin-based adhesive, an epoxy resin-based adhesive, and a silicone resin-based adhesive having a terminal silyl group. Moreover, you may ensure favorable electrical conductivity between the 1st member 61 and the 2nd member 62 by using a conductive adhesive as an adhesive agent.

  When the separator 20 is configured by the first member 61 and the second member 62, the complicated groove 2 in the separator 20 is formed in the first member 61 made of metal. It can be easily formed by bending or pressing a metal plate. On the other hand, since the complicated groove 2 is not formed in the second member 62, the second member 62 can be easily formed even if the second member 62 is formed by compression molding a molding material. Can do. Furthermore, since the cooling manifold is formed not on the metal first member 61 but on the second member 62 formed from a cured material of the molding material, the cooling water flows through the cooling manifold hole 133. However, corrosion hardly occurs on the inner surface of the cooling manifold hole 133.

In the present embodiment, the true density of the graphite particles contained in the second member 62 is preferably 2.22 g / cm ³ or more. Moreover, it is preferable that content of the graphite particle with respect to the 2nd member 62 whole is the range of 70-80 mass%. Furthermore, the corrosion current of the second member 62 is preferably 10 μA / cm ² or less. Details of the molding material and the thermosetting resin and graphite particles contained therein will be described later.

  Graphite particles with high true density have high crystallinity, and when the second member 62 contains such graphite particles, the corrosion current of the second member 62 is lowered. For this reason, the corrosion resistance of the second member 62 is increased. In particular, even if cooling water flows through the cooling manifold hole 133 of the second member 62 in the separator 20 incorporated in the fuel cell, Corrosion is further less likely to occur on the inner surface of the manifold hole 133. Details of the graphite particles will be described later.

  When the content of the graphite particles is in the range of 70 to 80% by mass, the second member 62 is provided with excellent conductivity and mechanical strength while the corrosion current of the second member 62 is reduced. High gas permeability is imparted to the second member 62.

As described above, the corrosion current of the second member 62 is preferably 10 μA / cm ² or less. Corrosion current refers to an aqueous solution of sodium sulfate adjusted to have a conductivity of 200 μS / cm, a second member 62 as a working electrode, and platinum electrodes as counter electrodes arranged at intervals of 30 mm. The value of the current flowing between the electrodes, measured when a voltage of 20 V is applied for 48 hours. Thus, since the corrosion current of the second member 62 is small, the corrosion resistance of the second member 62 is particularly high. The corrosion current of the second member 62 can be appropriately adjusted by adjusting the content of the graphite particles in the range of 70 to 80% by mass according to the constituent components of the molding material.

  When two small pieces having a size of 30 mm × 30 mm in plan view are cut out from the second member 62, the contact resistance ratio between the two small pieces is in a range of 0.9 to 1.1 regardless of the position at which the small pieces are cut out. (If the contact resistance of one small piece is 1, the contact resistance of the other small piece is preferably in the range of 0.9 to 1.1). The small piece is obtained by cutting the second member 62 in the thickness direction, and the plan view means observing the second member 62 in the thickness direction. In this case, the variation in contact resistance in the second member 62 is reduced, and in such a second member 62, the partial orientation of the graphite particles is suppressed. Thereby, good electrical characteristics of the second member 62 are ensured. Furthermore, the high mechanical strength of the second member 62 is ensured by suppressing the partial orientation of the graphite particles in the second member 62.

  The contact resistance is determined by placing the carbon paper on the top and bottom of the small piece, further placing the copper plates on the top and bottom, and applying a surface pressure of 1.0 MPa in the up and down direction. It is a value calculated from the result of measuring with a voltmeter and measuring the current flowing between two copper plates with an ammeter.

  The molding material used for manufacturing the second member 62 includes a resin component and graphite particles.

  The molding material preferably does not contain a primary amine and a secondary amine. That is, it is preferable that this molding material does not contain a compound having substituents —NH and —NH 2. Furthermore, it is preferable that the molding material does not contain a tertiary amine. Thus, when the molding material does not contain an amine, the second member 62 formed from the molding material does not poison the platinum catalyst in the fuel cell, and the fuel cell is used for a long time. Reduction of electromotive force is suppressed.

  The resin component contains a thermosetting resin. The thermosetting resin preferably contains at least one of an epoxy resin and a thermosetting phenol resin. Epoxy resins and thermosetting phenol 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.

  The content of the epoxy resin and the thermosetting phenol resin with respect to the total amount of the thermosetting resin is preferably in the range of 50 to 100% by mass. It is particularly preferable if the thermosetting resin contains only an epoxy resin, only a thermosetting phenol resin, or only an epoxy resin and a thermosetting phenol resin.

  The epoxy resin is preferably solid, and particularly preferably has a melting point in the range of 70 to 90 ° C. Thereby, the change of material decreases and the handleability of the molding material at the time of shaping | molding improves. When this melting point is less than 70 ° C., aggregation tends to occur in the molding material, and the handleability may be lowered. If a resin having a low melt viscosity is selected as the epoxy resin, the molding material and the second member 62 can be highly filled with graphite particles while maintaining good moldability of the molding material. In addition, a part of epoxy resin may be liquid within the range where the said effect | action is exhibited.

  As the epoxy resin, an ortho cresol novolak type epoxy resin, a bisphenol type epoxy resin, a biphenyl type epoxy resin, a phenol aralkyl type epoxy resin having a biphenylene skeleton, or the like is preferably used. This ortho-cresol novolac type epoxy resin, bisphenol type epoxy resin, and phenol aralkyl type epoxy resin having a biphenylene skeleton are excellent in that they have a good melt viscosity and a small amount of impurities, and in particular, a small amount of ionic impurities.

  In particular, the epoxy resin is composed only of an ortho cresol novolac type epoxy resin, or at least one selected from an ortho cresol novolac type epoxy resin, a bisphenol type epoxy resin, a biphenyl type epoxy resin, and a phenol aralkyl type epoxy resin having a biphenylene skeleton. It is preferable that the component (it is called 1st component) which becomes. When the ortho-cresol novolac type epoxy resin is an essential component, the moldability of the molding material is improved and the heat resistance of the second member 62 is improved. Furthermore, manufacturing costs can be reduced. The proportion of the ortho-cresol novolac type epoxy resin in the first component is in the range of 50 to 100% by mass from the viewpoint of improving the moldability, improving the heat resistance of the second member 62, and reducing the manufacturing cost. Is preferable, and the range of 50 to 70% by mass is particularly preferable.

  It is also preferable to use a bisphenol type epoxy resin, a biphenyl type epoxy resin, or a phenol aralkyl type epoxy resin having a biphenylene skeleton together with the orthocresol novolac type epoxy resin. In this case, the melt viscosity of the molding material can be further reduced, and the toughness can be improved when the thinner second member 62 is produced.

  In particular, when a bisphenol F type epoxy resin is used, the viscosity of the molding material is reduced, and the moldability of the molding material is particularly improved. In this case, the content of the bisphenol F-type epoxy resin in the first component is preferably in the range of 30 to 50% by mass.

  When a biphenyl type epoxy resin is used, since this biphenyl type resin has a low melt viscosity, the fluidity of the molding material is remarkably improved, and the thin moldability of the molding material is particularly improved. In this case, the content of the biphenyl type epoxy resin in the first component is preferably in the range of 30 to 50% by mass.

  When a phenol aralkyl epoxy resin having a biphenylene skeleton is used, the strength and toughness of the second member 62 can be improved, and the hygroscopicity of the second member 62 can be reduced. For this reason, the mechanical characteristics of the second member 62, the conductivity, and the stability of the characteristics during long-term use are improved. In this case, the ratio of the phenol aralkyl type epoxy resin having a biphenylene skeleton in the first component is preferably in the range of 30 to 50% by mass.

  The content of the first component with respect to the total amount of the thermosetting resin in the molding material is preferably in the range of 50 to 100% by mass.

  The first component is contained in the molding material as at least a part of the epoxy resin in the thermosetting resin. That is, the thermosetting resin other than the first component is selected from, for example, an epoxy resin other than the first component, a thermosetting phenol resin, a vinyl ester resin, a polyimide resin, an unsaturated polyester resin, a diallyl phthalate resin, and the like. One or more kinds of resins may be used. However, it is desirable not to use a resin containing an ester bond because it may hydrolyze in an acid resistant environment. In addition, a polyimide resin is also suitable as a thermosetting resin in that it contributes to improving the heat resistance and acid resistance of the second member 62. As the polyimide resin, it is particularly preferable to use a bismaleimide resin, and it is preferable to use 4,4-diaminodiphenyl bismaleimide, for example. When 4,4-diaminodiphenyl bismaleimide is used, the heat resistance of the second member 62 is further improved.

  When a thermosetting phenol resin is used, it is particularly preferable to use a phenol resin that undergoes a polymerization reaction by ring-opening polymerization. Examples of such phenol resins include benzoxazine resins. In this case, since gas due to dehydration is not generated in the molding process of the molding material, voids are not generated in the molded product, and therefore, a decrease in gas permeability of the second member 62 is suppressed. It is also preferable to use a resol-type phenol resin, for example, a resol-type phenol having a structure of ortho-ortho 25-35%, ortho-para 60-70%, para-para 5-10% by 13C-NMR analysis. A resin is preferably used. The resol resin is usually in a liquid state, but since the softening point of the resol type phenol resin can be easily adjusted, a resol type phenol resin having a melting point of 70 to 90 ° C. can be easily obtained. By using a resol type phenolic resin having a melting point of 70 to 90 ° C., alteration of the molding material is suppressed, and the handleability of the molding material during molding is improved. When this melting point is less than 70 ° C., aggregation tends to occur in the molding material, and the handleability may be lowered.

  Other resins other than the epoxy resin and the thermosetting phenol resin may be used in combination. For example, one or more kinds of resins selected from polyimide resins, unsaturated polyester resins, diallyl phthalate resins, vinyl ester resins, and the like may be used. However, it is desirable not to use a resin containing an ester bond because it may hydrolyze in an acid resistant environment.

  A polyimide resin is also suitable as the thermosetting resin in that it contributes to improving the heat resistance and acid resistance of the second member 62. As such a polyimide resin, a bismaleimide resin and the like are particularly preferable, and specific examples thereof include 4,4-diaminodiphenyl bismaleimide. By using such a resin together, the heat resistance of the second member 62 can be further improved.

  When an epoxy resin is used, the resin component preferably contains a curing agent, and this curing agent preferably contains a phenolic compound. Examples of the phenol compound include novolak type phenol resins, cresol novolac type phenol resins, polyfunctional phenol resins, aralkyl-modified phenol resins, and the like.

  The content of the phenolic compound relative to the total amount of the curing agent is determined depending on the amount of the epoxy resin used. Further, it is particularly preferable that the curing agent is only a phenol compound.

  When a curing agent other than a phenol compound is used, a non-amine compound is preferably used as the curing agent. In this case, the electric conductivity of the second member 62 is maintained at a high level, and poisoning of the catalyst of the fuel cell is suppressed. It is also preferred that no acid anhydride compound is used as the curing agent. When an acid anhydride-based compound is used, the cured product is hydrolyzed in an acidic environment such as a sulfuric acid acidic environment, causing a decrease in the electrical conductivity of the second member 62, or the second member. There is a possibility that the elution of impurities from 62 increases.

  When an epoxy resin is used as the thermosetting resin, the epoxy resin in the thermosetting resin and the phenolic compound in the curing agent have an equivalent ratio of the epoxy resin to the phenolic compound of 0.8 to 1.2. It is preferable to mix | blend so that it may become a range.

The graphite particles reduce the electrical specific resistance of the second member 62 and improve the conductivity of the second member 62. As the graphite particles, graphite particles having a true density of 2.22 g / cm ³ or more are used. Graphite particles having a high true density have high crystallinity, and if the second member 62 contains such graphite particles, the corrosion current of the second member 62 is lowered, and therefore the corrosion resistance of the second member 62 is reduced. Get higher. The true density of the graphite particles is particularly preferably 2.25 g / cm ³ or more. There is no particular limitation on the upper limit of the true density of the graphite particles, considering the true density of the available graphite particles, it is preferable that the true density of 2.32 g / cm ³ or less, 2.30 g / cm ³ or less More preferably, the true density of the graphite particles is a value measured by a constant volume expansion method. The true density of the graphite particles is, for example, using a dry automatic densimeter (Accuic II 1340) manufactured by Shimadzu Corporation, helium gas is used for the measurement, the introduction pressure (gauge pressure) is 134.45 kPag, and the number of purges is 10 times. The measurement is performed under the conditions of 10 run times and an equilibrium judgment pressure (gauge pressure) of 0.345 kPag.

  Such high-density graphite particles can be appropriately selected from natural graphite powder. As the graphite particles, artificial graphite powder having high crystallinity (for example, artificial graphite powder subjected to a treatment for improving crystallinity) may be used.

  The graphite particles are preferably purified. In this case, since ash and ionic impurities in the graphite particles are low, elution of impurities from the second member 62 is suppressed. The ash content in the graphite particles is preferably 0.05% by mass or less. If the ash content exceeds 0.05% by mass, the characteristics of the fuel cell manufactured by using the second member 62 may be deteriorated. is there.

  The average particle size of the graphite particles is preferably in the range of 15 to 100 μm. When the average particle size is 10 μm or more, the moldability of the molding material is improved, and when the average particle size is 100 μm or less, the surface smoothness of the second member 62 is improved. In order to improve the moldability, the average particle size is preferably 30 μm or more, and the surface smoothness of the second member 62 is particularly improved and the surface of the second member 62 is improved as described later. In order for the arithmetic average height Ra (JIS B0601: 2001) to be in the range of 0.4 to 1.6 μm, particularly less than 1.0 μm, the average particle size is preferably 70 μm or less. In particular, the average particle size is preferably in the range of 30 to 70 μm.

  In particular, when the thin second member 62 is produced, the graphite particles preferably have a particle size that passes through a 100 mesh sieve (aperture 150 μm). If the graphite particles contain particles that do not pass through a 100-mesh sieve, graphite particles having a large particle size will be mixed in the molding material, especially when the molding material is molded into a thin sheet. The moldability of the will be reduced.

  The aspect ratio of the graphite particles is preferably 10 or less. In this case, anisotropy is suppressed in the second member 62 and deformation such as warpage is also suppressed.

  Regarding the reduction of the anisotropy of the second member 62, the flow direction of the molding material at the time of molding in the second member 62 (direction perpendicular to the thickness direction of the second member 62) and the flow direction. It is preferable that the ratio of the contact resistance between the direction perpendicular to the direction (thickness direction of the second member 62) is 2 or less.

  It is also preferable that the entire graphite particles have particularly two or more particle size distributions, that is, the entire graphite particles are a mixture of two or more particle groups having different average particle diameters. In this specification, the particle group means an aggregate of a plurality of particles constituting at least a part of the entire graphite particle. It is preferable that the entire graphite particles are a mixture of a particle group having an average particle diameter of 1 to 50 μm and a particle group having an average particle diameter of 30 to 100 μm. When graphite particles having such a particle size distribution are used, it is expected that particles having a large particle size have a small surface area, so that the molding material can be kneaded even if the resin component content is small. . Further, the contact property between the particles is improved by the particles having a small particle diameter, and the strength of the second member 62 is also expected to be improved. As a result, the density of the second member 62 is improved, the conductivity is improved, and the gas is impermeable. Improvement of performance, such as improvement of property and improvement of strength, is achieved. The mixing ratio of the particle group having an average particle diameter of 1 to 50 μm and the particle group having an average particle diameter of 30 to 100 μm is appropriately adjusted, and the mixing mass ratio of the former to the latter is particularly 40:60 to 90:10, particularly 65. : It is preferable that it is 35-85: 15.

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

  The ratio of the graphite particles in the molding material is preferably in the range of 70 to 80% by mass with respect to the entire solid content in the molding material. Thus, when the ratio of the graphite particles is 70% by mass or more, sufficiently excellent conductivity is imparted to the second member 62, and the mechanical strength of the second member 62 is sufficiently improved. Further, when this ratio is 80% by mass or less, a sufficiently excellent moldability is imparted to the molding material and a sufficiently excellent gas permeability is imparted to the second member 62.

  The molding material may contain additives such as a curing catalyst, a wax (release agent), and a coupling agent as necessary.

  Although it does not restrict | limit especially as a curing catalyst (curing accelerator), In order that a molding material does not contain a primary amine and a secondary amine, it is preferable that a non-amine type compound is used. For example, amine-based diaminodiphenylmethane and the like are not preferable because the residue may poison the fuel cell catalyst. In addition, imidazoles are less preferred because they easily release chlorine ions after curing, and may cause impurity elution.

  However, 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 the holding temperature is 5% or less, and is in the second place The use of a substituted imidazole having a hydrocarbon group is preferable in that the storage stability of the molding material is improved. Further, in particular, when the thin second member 62 is manufactured, the volatility of the solvent when the sheet-like second member 62 is formed from the molding material prepared in a varnish shape, the second The smoothness of the member 62 is improved. As this substituted imidazole, a substituted imidazole having 6 to 17 carbon atoms in the hydrocarbon group at the 2-position is particularly preferably used. Specific examples thereof include 2-undecylimidazole, 2-heptadecylimidazole, 2- Examples include phenylimidazole and 1-benzyl-2-phenylimidazole. Of these, 2-undecylimidazole and 2-heptadecylimidazole are preferred. These compounds are used alone or in combination of two or more. The content of such a substituted imidazole can be adjusted as appropriate, whereby the molding curing time can be adjusted. The content of the substituted imidazole 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 molding material.

  Further, a phosphorus compound is preferably used as the curing catalyst. A phosphorus compound and the substituted imidazole may be used in combination. An example of a phosphorus compound is triphenylphosphine. When such a phosphorus compound is used, elution of chlorine ions from the second member 62 is suppressed.

  It is also preferred that the molding material contains a compound represented by the following structural formula (1) as a curing accelerator. In this case, the moisture resistance of the second member 62 is improved. Moreover, the compound represented by the structural formula (1) does not cause a decrease in the glass transition temperature of the second member 62, a decrease in rigidity during heating, a deterioration in continuous formability, and the like. Rather, by using the compound represented by the structural formula (1), the glass transition temperature of the second member 62 is increased, the thermal rigidity is improved, and the releasability at the time of molding the molding composition. Can improve the continuous formability.

  Furthermore, ionic impurities are not easily eluted from the compound represented by the structural formula (1). For this reason, by using the compound represented by the structural formula (1), elution of ionic impurities from the second member 62 is suppressed, and characteristics such as a decrease in starting voltage of the fuel cell due to the elution of impurities are reduced. It is suppressed. It is assumed that the elution of ionic impurities from the compound represented by the structural formula (1) hardly occurs because the acid dissociation constant (pKa) of this compound is small.

  The ratio of the compound represented by the structural formula (1) to the total amount of the curing accelerator is preferably in the range of 20 to 100% by mass. If this ratio is less than 20% by mass, the glass transition temperature (Tg) of the second member 62 may not be sufficiently increased.

  The content of such a curing catalyst is appropriately adjusted, but is preferably in the range of 0.5 to 3 parts by mass with respect to the epoxy resin in the molding material.

  Although it does not restrict | limit especially as a coupling agent, In order that a molding material does not contain a primary amine and a secondary amine, it is preferable that aminosilane is not used. If aminosilane is used, the fuel cell catalyst may be poisoned, which is not preferable. It is also preferred that mercaptosilane is not used as a coupling agent. Similarly, when this mercaptosilane is used, the fuel cell catalyst may be poisoned.

  Examples of coupling agents include silicon-based silane compounds, titanate-based, and aluminum-based coupling agents. For example, epoxy silane is suitable as a silicon-based coupling agent.

  When the epoxysilane coupling agent is used, the amount used is preferably in the range where the content in the solid content of the molding material is 0.5 to 1.5% by mass. In this range, the coupling agent can be sufficiently prevented from bleeding on the surface of the second member 62.

  The coupling agent may be previously attached to the surface of the graphite particles by spraying or the like. The addition amount in that case is appropriately set in consideration of the specific surface area of the graphite particles and the coatable area per unit mass of the coupling agent (area that can be coated with the coupling agent). The addition amount of the coupling agent is preferably adjusted so that the total amount of the area that can be coated with the coupling agent is in the range of 0.5 to 2 times the total amount of the surface area of the graphite particles. In this range, bleeding of the coupling agent on the surface of the second member 62 is sufficiently suppressed, thereby suppressing contamination of the mold surface.

  Although it does not restrict | limit especially as a wax (internal mold release agent), The internal mold release agent which phase-separates without being incompatible with the thermosetting resin and hardening | curing agent in a molding material at 120-190 degreeC may be used. preferable. Examples of such an internal mold release agent include at least one 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 molding material, so that the release property of the second member 62 is improved.

  The content of the internal mold release agent is appropriately set depending on the complexity of the shape of the second member 62, the groove depth, the ease of release from the mold surface, such as the draft, etc. It is preferable that it is the range of 0.1-2.5 mass% with respect to the solid content whole quantity in. When the content is 0.1% by mass or more, the second member 62 exhibits sufficient releasability at the time of molding the mold, and when the content is 2.5% by mass or less The hydrophilicity of the member 62 is maintained sufficiently high. The content of the wax 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 content of ionic impurities in the second member 62 is preferably a sodium content of 5 ppm or less and a chlorine content of 5 ppm or less in terms of mass ratio with respect to the total amount of the molding material. For this purpose, it is preferable that the content of ionic impurities in the molding material is a sodium content of 5 ppm or less and a chlorine content of 5 ppm or less by mass ratio with respect to the total amount of the molding material. In this case, the elution of the ionic impurities from the second member 62 is suppressed, and thus the characteristic deterioration such as the decrease in the starting voltage of the fuel cell due to the impurity elution is suppressed.

  In order to reduce the content of ionic impurities in the second member 62 and the molding material as described above, each component such as a thermosetting resin, a curing agent, graphite, and other additives constituting the molding material. It is preferable that the content of each of the ionic impurities is a sodium content of 5 ppm or less and a chlorine content of 5 ppm or less by mass ratio with respect to each component.

  The content of the ionic impurities is derived based on the amount of the ionic impurities in the extraction water containing the ionic impurities eluted from the object (molding material, thermosetting resin, etc.). The extraction water is heated in 90 ° C. for 50 hours in a state where the object is put in the ion-exchanged water so that the object has a ratio of 100 ml of ion-exchanged water to 10 g of the object. It can be obtained. Ionic impurities in the extracted water are evaluated by ion chromatography. The amount of ionic impurities in the target is derived by converting the amount of ionic impurities in the extracted water into a mass ratio with respect to the target.

  The molding material is preferably prepared such that the TOC (total organic carbon) of the second member 62 formed from this composition is 100 ppm or less.

  In the TOC, the second member 62 is charged into the ion-exchanged water at a rate of 100 ml of ion-exchanged water with respect to 10 g of the mass of the second member 62. It is a numerical value measured from a solution obtained by heating for a period of time. Such a TOC can be measured by, for example, a total organic carbon analyzer “TOC-50” manufactured by Shimadzu in accordance with JIS K0102. In the measurement, the CO2 concentration generated by the combustion of the sample is measured by a non-dispersive infrared gas analysis method, whereby the carbon concentration in the sample is quantified. By measuring the carbon concentration, the organic substance concentration contained in the second member 62 is indirectly measured. When inorganic carbon (IC) and total carbon (TC) in a sample are measured, total organic carbon (TOC) is derived from the difference between total carbon and inorganic carbon (TC-IC).

  When the TOC is 100 ppm or less, deterioration of the characteristics of the fuel cell is further suppressed.

  The value of TOC can be reduced by selecting a high-purity component as each component constituting the molding material, adjusting the equivalent ratio of the resin, or performing a post-curing treatment during molding.

  There is a possibility that a metal component is mixed as an impurity in the raw material component, and the molding material and the second member 62 are mixed with a metal component derived from the raw material component as an impurity, a metal component mixed during manufacture, and the like. There is a possibility. If a metal component is mixed in the second member 62, the corrosion current of the second member 62 increases. Therefore, when the second member 62 is manufactured, it is preferable to perform a process for reducing the content of the metal component on at least one of the raw material component, the molding material, and the second member 62. . In this case, the content of the metal component of the second member 62 is reduced, and thereby the corrosion current of the second member 62 is further reduced. In particular, at least the molding material is preferably subjected to a treatment for reducing the content of the metal component.

  An example of a process for reducing the content of the metal component relative to the raw material component is a process of attracting the metal component in the raw material component using a magnet. Among the raw material components, the treatment for reducing the content of the metal component, particularly with respect to the graphite particles, includes a treatment for washing the graphite particles with a strongly acidic solution having a pH of 2 or less. As the strongly acidic solution, for example, aqua regia obtained by mixing concentrated nitric acid having a concentration of 69% by mass and concentrated hydrochloric acid having a concentration of 36% by mass in a ratio of 1: 3 by volume ratio, hydrochloric acid having a concentration of 15% by mass or more, At least one selected from sulfuric acid having a concentration of 15% by mass or more and nitric acid having a concentration of 15% by mass or more can be used. In this case, the content of the metal component in the graphite particles is easily reduced. The concentration of the hydrochloric acid water, the sulfuric acid water and the nitric acid water is preferably 30% by mass or less from the viewpoint of operability.

  The treatment for reducing the metal component content for the molding material is similar to the treatment for reducing the metal component content for the raw material component, and the metal component in the molding material is sucked using a magnet. And the like.

  The molding material is prepared by blending the raw material components as described above, and the second member 62 is obtained by molding the molding material. The molding material is formed into an appropriate shape such as a granular shape or a sheet shape.

  When the molding material is granular, the raw material components as described above are stirred and mixed with, for example, a stirrer or the like, or further sized with a granulator or the like, whereby a molding material is obtained.

  The molding material may be in the form of a sheet. In particular, when the thin second member 62 is manufactured, a sheet-like molding material is preferably used. When a sheet-shaped molding material is used, a thin second member 62 having a thickness of, for example, 0.2 to 1.0 mm can be easily obtained, and the thickness accuracy of the second member 62 is increased.

  In order to prepare the sheet-shaped molding material, first, a liquid composition containing the raw material components as described above is prepared. The liquid composition contains a solvent as necessary. As the solvent, for example, polar solvents such as methyl ethyl ketone, methoxypropanol, N, N-dimethylformamide, dimethyl sulfoxide are preferable. Only 1 type may be used for a solvent, or 2 or more types may be used together. The amount of the solvent used is appropriately set in consideration of moldability and the like, but is preferably adjusted so that the viscosity of the liquid composition is in the range of 1000 to 5000 cps (1000 to 5000 mPa · s). In addition, as above-mentioned, the solvent should just be used as needed, and when the thermosetting resin in a raw material component is a liquid resin, a solvent does not need to be used.

  By forming this liquid composition into a sheet shape, a sheet-shaped molding material is obtained. The liquid composition is formed into a sheet shape by, for example, casting (progressive) molding, and is dried by heating with casting, or is semi-cured to obtain a sheet-shaped molding material. . This sheet-shaped molding material is formed into an appropriate dimension by cutting (cutting) or punching into a predetermined plane dimension as necessary.

  When a sheet-shaped molding material is formed by a casting method, a plurality of types of film thickness adjusting means can be applied. The casting method using such a plurality of types of film thickness adjusting means is realized by using a multi-coater that has already been put into practical use, for example. As a film thickness adjusting means for casting, it is preferable to use a slit knife and at least one of a doctor knife and a wire bar, that is, either one or both. The thickness of the sheet-shaped molding material is preferably 0.05 mm or more, and more preferably 0.1 mm or more. The thickness is preferably 0.5 mm or less, and more preferably 0.3 mm or less. As described above, when the thickness of the sheet-shaped molding material is 0.5 mm or less, the second member 62 can be made thinner and lighter, and the cost thereof can be reduced. In particular, the thickness is 0.3 mm or less. If so, the remaining of the solvent inside the sheet-shaped molding material when using the solvent is effectively suppressed. In addition, when the thickness is less than 0.05 mm, the advantage in manufacturing the second member 62 is not sufficiently exhibited, and in consideration of formability, the thickness is preferably 0.1 mm or more.

  The second member 62 is obtained by molding the molding material. As a molding method, compression molding is preferably employed.

  When the second member 62 is manufactured by compression molding the molding material, the disk flow of the molding material is preferably 80 to 100 mm. In the disk flow, 3 g of a molding material is densely arranged at one place on a flat surface, and a long diameter (longest length) of a molded body formed when this is compressed for 30 seconds under conditions of a temperature of 170 ° C. and a pressure of 5 MPa. Diameter). The disk flow of the molding material can be adjusted as appropriate by changing the composition of the molding material. For example, if the graphite content in the molding material decreases, the disk flow increases, and if the graphite content increases, the disk flow decreases. If the content of the curing accelerator in the molding material decreases, the disk flow increases. If the content of the curing accelerator in the molding material increases, the disk flow decreases. Furthermore, when the types of components in the molding material are appropriately changed, the disk flow increases or decreases accordingly.

  Thus, when the disk flow of the molding material is 80 to 100 mm, the fluidity of the molding material during compression molding is increased. Therefore, even though the molding material contains highly crystalline graphite particles and the second member 62 having a complicated shape is manufactured from the molding material by compression molding, the second member 62 is produced. It becomes difficult for the graphite particles to orient within. As a result, partial orientation in the second member 62 is suppressed, and when two small pieces having a size of 30 mm × 30 mm in plan view are cut out from the second member 62, the small pieces are cut from any position. However, the contact resistance ratio between the small pieces is in the range of 0.9 to 1.1.

  The second member 62 is preferably subjected to blasting or the like to remove the surface skin layer of the second member 62 and adjust the surface roughness of the second member 62.

  The arithmetic average height Ra (JIS B0601: 2001) of the surface of the second member 62 is preferably in the range of 0.4 to 1.6 μm. In this case, the corrosion current of the second member 62 is further reduced, and the corrosion resistance of the second member 62 is further improved. Further, gas leakage at the joint between the second member 62 and the gasket 12 is suppressed. For this reason, it is not necessary to mask the part joined to the gasket 12 in the second member 62 during the wet blasting process, and the production efficiency of the second member 62 is improved. It is difficult for the arithmetic average height Ra to be less than 0.4 μm, and if this value is greater than 1.6 μm, the gas leak may not be sufficiently suppressed. The arithmetic average height Ra of the surface of the second member 62 is particularly preferably 1.2 μm or less. Further, when the arithmetic average height Ra of the surface of the second member 62 is less than 1.0 μm, the gas leak is particularly suppressed, and the fastening force at the time of manufacturing the cell stack is reduced as the thickness of the second member 62 is reduced. Even if it becomes low, the said gas leak is fully suppressed. As described above, the arithmetic average height Ra of the surface of the second member 62 is preferably 0.4 μm or more, and more preferably 0.6 μm or more.

The contact resistance of the surface of the second member 62 is preferably 15 mΩcm ² or less. In this case, the function of the separator 20 for transmitting the electric energy generated by the fuel cell to the outside is maintained at a high level.

  In the blasting process, it is preferable that the second member 62 is subjected to a wet blasting process, and in this process, a metal component is attracted by a magnet from a slurry containing abrasive grains such as alumina particles. There is a possibility that a metal component is mixed as an impurity in the abrasive grains used in the blasting process, and a metal component may be mixed in the slurry containing the abrasive grains during the blasting process. When blasting is performed using a slurry containing such a metal component, the metal component is driven from the abrasive grains onto the surface of the second member 62. However, when the metal component is attracted from the slurry by the magnet as described above and wet blasting is performed with the abrasive grains, the metal component is less likely to adhere to the second member 62 during blasting. That is, while the skin layer is removed and the surface roughness is adjusted by the wet blasting process, metal components such as metal foreign matters contained in the abrasive grains in the slurry are driven into the second member 62 during the wet blasting process. It becomes difficult. In the wet blasting process, the slurry is repeatedly used while being circulated, and when the metal component is attracted from the slurry by a magnet or the like during the circulation of the slurry, the metal component is attracted by the magnet from the abrasive grains in the slurry. However, wet blasting is performed by the abrasive grains.

  Further, the metal component may be attracted by the magnet from the second member 62 in the same manner as the processing for reducing the content of the metal component of the graphite particles. In this case, for example, the second member 62 is disposed between the pair of magnets, whereby the metal component is attracted from the second member 62. Note that the metal component may be removed from the second member 62 by an appropriate method other than attraction using a magnet. However, in the method of cleaning with a strong acid solution, the resin constituting the second member 62 may be dissolved, and in the ultrasonic cleaning, graphite particles may be detached from the second member 62. It is not preferable.

  The degree of adhesion of the metal component in the second member 62 obtained as described above is determined by washing the second member 62 with hot water at 90 ° C. for 1 hour and then heating and drying at 90 ° C. for 1 hour. This is confirmed by observing the surface of the second member 62 after the treatment. When a metal component adheres to the second member 62, a metal oxide (rust) is generated on the surface of the second member 62 by the treatment. Even if the surface of the second member 62 after the treatment is visually observed, it is preferable that the presence of the metal oxide (rust) is not confirmed. In particular, it is preferable that a metal oxide larger than 100 μm in diameter does not exist on the surface of the second member 62 after the treatment, and it is more preferable if a metal oxide larger than 50 μm in diameter does not exist. Further, it is particularly preferable if there is no metal oxide having a diameter larger than 30 μm.

The total amount of Fe, Co, and Ni exposed on the surface of the second member 62 is preferably 0.01 μg / cm ² or less. Furthermore, it is preferable that the total amount of Cr, Mn, Fe, Co, Ni, Cu and Zn exposed on the surface of the second member 62 is 0.01 μg / cm ² or less.

  The gasket 12 is laminated on the outer peripheral portion of the separator 20 for sealing. The gasket 12 has an opening 15 for accommodating the fuel electrode 31 and the oxidant electrode 32 in the membrane-electrode assembly 5 at a substantially central portion thereof, and the groove 2 for allowing the fluid of the separator 20 to flow through the opening 15. Is exposed. The gasket 12 has a fuel through hole 141 at a position on the outer peripheral side of the opening 15 that matches the fuel manifold hole 131 of the separator 20, and an oxidant through hole 142 at a position that matches the oxidant manifold hole 132. However, cooling through-holes 143 are formed at positions corresponding to the cooling manifold holes 133, respectively.

  Also in the electrolyte 4 in the membrane-electrode assembly 5, the fuel through hole 161 is oxidized at the outer peripheral portion of the electrolyte 4 at a position matching the fuel manifold hole 131 of the separator 20 at a position matching the oxidant manifold hole 132. Cooling through holes 163 are formed at positions where the agent through holes 162 coincide with the cooling manifold holes 133, respectively.

  In this single cell structure, the fuel manifold hole 131 of the separator 20, the fuel through hole 141 of the gasket 12, and the fuel through hole 161 of the electrolyte 4 communicate with each other for supplying and discharging fuel to the fuel electrode. The fuel flow path is configured. Further, the oxidizing agent manifold hole 132 of the separator 20, the oxidizing agent through hole 142 of the gasket 12, and the oxidizing agent through hole 162 of the electrolyte 4 communicate with each other, thereby supplying and discharging the oxidizing agent to and from the oxidizing electrode. An oxidant flow path is formed. Further, the cooling manifold hole 133 of the separator 20, the cooling through hole 143 of the gasket 12, and the cooling through hole 163 of the electrolyte 4 communicate with each other, thereby forming a cooling channel through which cooling water or the like flows.

  The fuel electrode 31, the oxidant electrode 32, and the electrolyte 4 are formed of a known material corresponding to the type of fuel cell. In the case of a polymer electrolyte fuel cell, the fuel electrode 31 and the oxidant electrode 32 are configured by supporting a catalyst on a substrate such as carbon cloth, carbon paper, or carbon felt. Examples of the catalyst in the fuel electrode 31 include a platinum catalyst, a platinum / ruthenium catalyst, and a cobalt catalyst. Examples of the catalyst in the oxidant electrode 32 include a platinum catalyst and a silver catalyst. In the case of a solid polymer fuel cell, the electrolyte 4 is formed of, for example, a proton conductive polymer membrane. In particular, in the case of a methanol direct fuel cell, for example, the proton conductivity is high, and the electronic conductivity and methanol permeability are high. It is formed from a fluorine resin or the like that is hardly shown.

  The gasket 12 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.

  When laminating the gasket 12 on the separator 20, for example, the gasket 12 formed in a sheet shape or a plate shape in advance is bonded or bonded to the separator 20. The gasket 12 may be laminated on the separator 20 by molding a material for forming the gasket 12 on the surface of the separator 20. For example, an unvulcanized rubber material is applied to a predetermined position on the surface of the separator 20 by screen printing or the like, and a desired shape is formed on the predetermined position on the surface of the separator 20 by vulcanizing the coating film of the rubber material. The gasket 12 is formed. In the vulcanization, heating, irradiation with radiation such as an electron beam, or other appropriate vulcanization methods are employed. In this case, the gasket 12 is easily laminated even on the thin separator 20. Further, the separator 20 is set in a mold, and an unvulcanized rubber material is injected into a predetermined position on the surface of the separator 20 and the rubber material is heated and vulcanized. A gasket 12 having a desired shape may be formed at a predetermined position on the surface of the separator 20. Thus, when the gasket 12 is formed by die molding, a molding method such as transfer molding, compression molding, injection molding or the like can be employed.

  FIG. 3 shows an example of a fuel cell 40 (cell stack) composed of a plurality of single cells. The fuel cell 40 communicates with a fuel supply port 171 and a discharge port 172 communicating with the fuel flow channel, an oxidant supply port 181 and a discharge port 182 communicating with the oxidant flow channel, and a cooling flow channel. A cooling water supply port 191 and a discharge port 192.

  The fuel cell 40 is operated by supplying a fuel such as hydrogen gas from the fuel supply port 171 and an oxidant such as oxygen gas from the oxidant supply port 181. While the fuel cell 40 is operating, cooling water is supplied to the fuel cell from the cooling water supply port 191. For this reason, the temperature of the fuel cell is adjusted to an appropriate temperature for operation. As the cooling water, pure water is preferably used.

  The fuel cell 40 including the separator 20 according to the present embodiment operates stably for a long time because the separator 20 has high corrosion resistance and strength. In particular, the cooling manifold of the separator 20 even if the conductivity of the cooling water rises due to the metal constituting the piping through which the cooling water circulates, the metal in the fuel cell, the resin, etc. are eluted into the cooling water. The holes 133 are less likely to be corroded, and accordingly, leakage of the cooling water from the fuel cell 40 due to such corrosion is less likely to occur.

  Examples of the present invention will be described below. In addition, this invention is not limited to this Example.

[Example 1]
(Production of the first member)
A 0.3 mm rolled clad material provided with a core material made of SUS and a surface layer made of Ti laminated on the core material was prepared as a metal plate. A first member was obtained by pressing the metal plate into a corrugated plate. The dimension of this first member was 175 mm × 225 mm × 1.0 mm. Further, 57 grooves each having a width of 1 mm, a length of 180 mm, and a depth of 0.6 mm were formed on both surfaces of the first member by the press molding.

(Production of second member and separator)
A cresol novolac type epoxy resin (Nippon Kayaku Co., Ltd., EOCN-1020-75, epoxy equivalent 199, melting point 75 ° C.) and a novolac type phenol resin (Gunei Chemical Industry Co., Ltd., PSM6200, OH equivalent 105) The cresol novolac type epoxy resin with respect to the type phenol resin was blended so that the equivalent ratio was 0.9, and triphenylphosphine (manufactured by Hokuko Chemical Co., Ltd., TPP) was added in a proportion of 0.12% by mass, graphite particles (average particles) Artificial graphite particles having a diameter of 50 μm and a true density of 2.25 g / cm ³ are 75% by mass, epoxysilane (manufactured by Nihon Unicar Co., Ltd., product number A187) is 0.6% by mass, natural carnauba wax (Daiichi) Chemical Industry Co., Ltd., product number H1-100, melting point 83 ° C.) was blended at a ratio of 0.1 mass%. The resulting mixture was stirred and mixed in a stirring mixer (Dalton 5XDMV-rr type), and the resulting mixture was pulverized to a particle size of 500 μm or less with a granulator. Thereby, a molding material was obtained.

  In addition, the true density of the graphite particles is a value measured by a constant volume expansion method using a dry automatic densimeter (Acupic II 1340) manufactured by Shimadzu Corporation. In the measurement, helium gas was used, the introduction pressure (gauge pressure) was 134.45 kPag, the number of purges was 10, the number of runs was 10, and the equilibrium judgment pressure (gauge pressure) was 0.345 kPag.

  With the first member placed in the compression mold, the molding material is compression molded in this compression mold under the conditions of a mold temperature of 170 ° C., a molding pressure of 35.3 MPa, and a molding time of 2 minutes. did.

By this compression molding, the second member was formed into a frame shape having an outer dimension of 200 mm × 250 mm, an opening dimension of 165 mm × 200 mm, and a thickness dimension of 1.0 mm. Furthermore, six manifold holes with an opening area of 3.5 cm ² were formed in the second member by this compression molding.

  Thereby, the 1st member and the 2nd member were integrated simultaneously with producing the 2nd member, and the separator was obtained.

  The surface of the second member in this separator 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 ion exchange. It was washed with water and further dried with hot air. The result of measuring the arithmetic average height Ra (JIS B0601: 2001) of the surface of the second member after this treatment was 0.9 μm.

[Example 2]
In Example 1, artificial graphite particles having an average particle diameter of 50 μm and a true density of 2.20 g / cm ³ were used as the graphite particles. The separator was obtained by the same method as Example 1 except it.

[Comparative Example 1]
A metal separator having a size of 200 mm × 250 mm × 1.0 mm was obtained by subjecting a rolled clad material having a thickness of 0.3 mm with SUS as the core material and Ti as the surface layer to press working.

[Corrosion evaluation]
The separator produced in each Example and Comparative Example was immersed in 400 mL of sulfuric acid aqueous solution (pH 2, temperature 90 ° C.) for 50 hours. Subsequently, in order to examine the degree of corrosion of the separator, the content of metal ions in the separator was measured using a sequential ICP emission spectroscopic analyzer (manufactured by SII Nanotechnology, model number SPS3520UV). The results are shown in the table below.

[Corrosion current evaluation]
The corrosion currents of the separators obtained in Example 1 and Example 2 were measured. In the measurement, a separator as a working electrode and a platinum electrode as a counter electrode are arranged at intervals of 30 mm in a sodium sulfate aqueous solution adjusted to have a conductivity of 200 μS / cm, and a voltage of 20 V is applied between the electrodes at a liquid temperature of 80 ° C. At the time when the voltage was applied for a period of time, the value of current flowing between the electrodes was measured. The results are shown in the table below.

1 Fuel Cell Separator 2 Groove 13 Manifold Hole 61 First Member 62 Second Member

Claims (3)

A metal first member in which a groove for circulating a fluid is formed;
A fuel cell separator comprising a manifold formed with a manifold hole communicating with the groove and formed of a cured material of a molding material containing a thermosetting resin and graphite. 2. The fuel cell separator according to claim 1, wherein a true density of the graphite is 2.22 g / cm ³ or more and a content of the graphite in the second member is in a range of 70 to 80 mass%. A fuel cell comprising the fuel cell separator according to claim 1.

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