JP6260886B2 - Method for producing separator with gasket for fuel cell, and separator with gasket for fuel cell - Google Patents

Description

  The present invention relates to a method of manufacturing a separator with a gasket for a fuel cell applied to a fuel cell, and a separator with a gasket for a fuel cell.

  In general, a fuel cell is composed of a cell stack formed by stacking several tens to several hundreds of single cells in series, whereby the fuel cell generates electromotive force. Fuel cells are classified into several types according to the type of electrolyte. Recently, solid polymer fuel cells using a solid polymer electrolyte membrane as an electrolyte have attracted attention as high-power fuel cells.

  A single cell of a polymer electrolyte fuel cell is configured by stacking, for example, a fuel cell separator, a gasket, and a membrane-electrode composite (see FIG. 2). In the separator, a manifold is formed in an outer peripheral portion surrounding a region where a gas supply / discharge groove is formed. Further, if necessary, a gasket for sealing is laminated on the outer peripheral portion of the separator.

  Among the components constituting such a fuel cell, the separator has a unique shape in which a gas supply / discharge groove and a manifold are formed. The separator has a function of separating the fuel, oxidant, and cooling water flowing in the fuel cell so as not to mix, and transmits 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 role of heat dissipation.

  The separator is formed from, for example, a molding material containing graphite particles and a resin component. When such a molding material is used, a separator is generally obtained by molding the molding material in a mold.

  Such a separator may be subjected to a blasting treatment for removing the skin layer, adjusting the surface roughness, a treatment for improving hydrophilicity, and the like. In addition, a gasket for sealing may be attached to the separator.

  For example, in Patent Document 1, a molding composition containing an epoxy resin, a phenolic compound, and graphite particles is molded, and the surface of the separator obtained thereby is subjected to wet blasting and remote atmospheric pressure. It is disclosed that a separator with a gasket for a fuel cell is obtained by sequentially performing plasma treatment, subsequently laminating a gasket on the surface of the separator, and further subjecting the surface of the separator to atmospheric pressure plasma treatment by a remote method again. Has been.

  However, in such a separator with a gasket for a fuel cell, even if a hydrophilic treatment such as an atmospheric pressure plasma treatment is performed, the hydrophilicity of the separator surface may not be sufficiently improved. For this reason, the groove | channel of the separator was obstruct | occluded with the water droplet, and the power generation efficiency of the fuel cell might fall for that reason.

JP 2011-150858 A

  The present invention has been made in view of the above-mentioned reasons, and the object of the present invention is to provide a method for efficiently producing a separator with a gasket for a fuel cell that can improve the hydrophilicity of the separator, and hydrophilicity. An object of the present invention is to provide a separator with a gasket for a fuel cell provided with a high separator.

A method for producing a separator with a gasket for a fuel cell according to the present invention includes:
Preparing a molding material containing graphite particles and a thermosetting resin component, wherein the ratio of the graphite particles is in the range of 70 to 90% by mass with respect to the total solid content;
Producing a separator by molding the molding material;
Laminating a gasket to the separator;
A step of subjecting the separator and the gasket to blasting; and a step of subjecting the separator to hydrophilic treatment for improving hydrophilicity of the surface after the blasting.

  It is preferable to adjust the arithmetic average height Sa defined by ISO 25178-2: 2012 on the surface of the separator to a range of 0.4 to 1.2 μm by the blast treatment.

  Moreover, it is preferable to adjust a static contact angle with the water of the surface of the said separator to 40 degrees or less by the said hydrophilic treatment.

The separator has a first surface in the thickness direction and a second surface opposite to the first surface, and causes the fuel gas or the oxidant gas to flow through the first surface. Forming a groove of
By the blasting process, the arithmetic average height Sa defined by ISO 25178-2: 2012 of the first surface is within a range of 0.8 to 1.2 μm, and the ISO 25178- 2: The arithmetic average height Sa defined by 2012 is preferably adjusted in the range of 0.5 to 0.7 μm.

  The hydrophilization treatment preferably includes at least one of plasma treatment for exposing the separator to plasma and ozone gas treatment for exposing the separator to ozone gas.

The separator with a gasket for a fuel cell according to the present invention is:
A separator containing a cured product of a thermosetting resin component and graphite particles, and a ratio of the graphite particles in the range of 70 to 90% by mass, and a gasket laminated on the separator,
The static contact angle with water on the surface of the separator is 40 ° or less, and the arithmetic average height Sa defined by ISO 25178-2: 2012 on the surface of the separator is 0.4 to 1.2 μm. It is a range.

The separator has a first surface in the thickness direction and a second surface opposite to the first surface, and causes the fuel gas or the oxidant gas to flow through the first surface. Groove is formed,
The arithmetic average height Sa defined by ISO 25178-2: 2012 of the first surface is in a range of 0.8 to 1.2 μm,
The arithmetic average height Sa defined by ISO 25178-2: 2012 of the second surface is preferably in the range of 0.5 to 0.7 μm.

  According to the method for manufacturing a separator with a gasket for a fuel cell according to the present invention, a separator with a gasket for a fuel cell including a gasket and having a highly hydrophilic separator can be efficiently manufactured.

  Although the separator with a gasket for a fuel cell according to the present invention includes a gasket, the hydrophilicity of the surface of the separator is increased.

(A) And (b) is a perspective view which shows the separator with the gasket for fuel cells in one Embodiment of this invention. It is a disassembled perspective view which shows the unit cell of the fuel cell in one Embodiment of this invention. It is a perspective view which shows the fuel cell in one Embodiment of this invention.

  Embodiments of the invention will be described below.

  FIG. 2 schematically shows the structure of a unit cell of a fuel cell separator 20 and a polymer electrolyte fuel cell including the separator 20 in the present embodiment. The unit cell is configured by stacking the separator 20, the gasket 12, and the membrane-electrode assembly 5. The membrane-electrode assembly 5 includes an oxidant electrode 31, a fuel electrode 32, and an electrolyte 4.

  The separator 20 is formed with a groove 2 for circulating fuel gas, oxidant gas or cooling water. In the present embodiment, one unit cell includes a cathode-side separator 21 and an anode-side separator 22 as the separator 20. Each of the cathode side separator 21 and the anode side separator 22 has a first surface in the thickness direction and a second surface on the opposite side of the first surface.

  In the unit cell, the first surface of the cathode separator 21 is disposed so as to overlap the oxidant electrode 31, and the first surface of the anode separator 22 is disposed so as to overlap the fuel electrode 32. The anode-side separator 22 has a region where a groove 2 (202) for allowing the fuel gas to flow is formed, and an outer peripheral portion surrounding the region. The groove 2 (202) for allowing the fuel gas to flow is formed on the first surface of the anode separator 22. Moreover, the cathode side separator 21 has the area | region in which the groove | channel for distribute | circulating oxidizing agent gas is formed, and the outer peripheral part surrounding this area | region. Although not shown, the groove for allowing the oxidant gas to flow is formed on the first surface of the cathode-side separator 21. A groove 2 (203) for circulating cooling water is formed on the second surface of the cathode separator 21.

  Further, when two unit cells are overlapped, the second surface of the cathode side separator 21 in one unit cell and the second surface of the anode side separator 22 in the other unit cell are overlapped. Between the cathode side separator 21 and the anode side separator 22, a flow path constituted by the groove 2 (203) is formed. This channel is a channel for circulating cooling water.

  In the present embodiment, the groove 203 for circulating the cooling water is formed on the second surface of the cathode side separator 21 as described above, but the groove for circulating the cooling water is formed on the anode side separator 22. It may be formed on the second surface. Further, a groove for circulating cooling water is formed on the second surface of the cathode-side separator 21, and a groove for circulating cooling water is also formed on the second surface of the anode-side separator 22. Good.

  Each separator 20 is formed with a manifold 13 having holes penetrating the separator 20. In the present embodiment, six separators 13 are formed in each separator 20. These manifolds 13 are opened at the outer peripheral portions of the first surface and the second surface of each separator 20. The six manifolds 13 include two fuel manifolds 131, two oxidant manifolds 132, and two cooling manifolds 133. The two oxidant through holes 131 and 131 in the cathode separator 21 communicate with a groove in the first surface of the cathode separator 21. The two fuel through holes 132 and 132 in the anode side separator 22 communicate with the groove 202 in the first surface of the anode side separator 22. Further, the two cooling manifolds 133 in the cathode side separator 21 communicate with the groove 203 in the second surface of the cathode side separator 21.

  In the present embodiment, as shown in FIG. 2, the straight groove 2 is formed in the separator 20. In general, the grooves 2 in the separator 20 include a serpentine type groove having a bend and a straight type groove having no bend. Of course, in the separator 20 shown in FIG. 2, the serpentine type groove 2 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 gas supply / discharge 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 ratio (A / B) of the width (A) to the depth (B) of the groove 2 is preferably 1 or more. In this case, the efficiency of the hydrophilization process mentioned later becomes high. Moreover, the opening area of the manifold 13 is formed in the range of 0.5-5.0 cm < ² >, for example.

  The gasket 12 is overlaid on the outer peripheral portion of each of the first surface of the cathode side separator 21 and the first surface of the anode side separator 22. Thereby, the gas leak of fuel gas and oxidant gas is suppressed. In the gasket 12, an opening 15 for accommodating the oxidant electrode 31 or the fuel electrode 32 in the membrane-electrode assembly 5 is formed at a substantially central portion thereof. In the opening 15, the groove 2 of the separator 20 is exposed. In addition, the gasket 12 has an oxidant through hole 141, a fuel through hole 142, and a cooling through hole at positions matching the oxidant through hole 131, the fuel through hole 132, and the cooling through hole 133 of the separator 20. Each hole 143 is formed.

  Further, when two unit cells are overlapped, the gasket 12 is also provided between the second surface of the cathode separator 21 in one unit cell and the second surface of the anode separator 22 in the other unit cell. Intervenes. This gasket 12 suppresses leakage of cooling water. An opening 15 is also formed at a substantially central portion of the gasket 12. In the opening 15, the groove 2 of the separator 20 is exposed. Further, the oxidant through-hole 141, the fuel through-hole 142, and the cooling gas are also provided in the gasket 12 at positions that coincide with the oxidant through-hole 131, the fuel through-hole 132, and the cooling through-hole 133 of the separator 20. Through holes 143 are formed respectively.

  The second surface of the cathode-side separator 21 and the second surface of the anode-side separator 22 may be bonded with an adhesive. In this case, the second surface of the cathode-side separator 21 and Even if no gasket is interposed between the second surface of the anode-side separator 22, leakage of the cooling water is suppressed. Although it does not specifically limit as an adhesive agent, It is preferable that an olefin resin adhesive agent is used. In this case, the elution of impurities from the adhesive is suppressed, and the durability of the fuel cell is increased.

  In the outer peripheral portion of the electrolyte 4 in the membrane-electrode assembly 5, an oxidant through-hole 161, a fuel are provided at positions that coincide with the oxidant through-hole 131, the fuel through-hole 132, and the cooling through-hole 133 of the separator 20. The through-hole 162 for cooling and the through-hole 163 for cooling are each formed.

  In this unit cell structure, the separator 20, the gasket 12, and the oxidant through holes 131, 141, 161 of the electrolyte 4 communicate with each other, so that the oxidant is supplied to and discharged from the oxidant electrode. A flow path is configured. Further, the fuel through-holes 132, 142, 162 communicate with each other to form a fuel flow path for supplying and discharging fuel to and from the fuel electrode. In addition, the cooling through holes 133, 143, and 163 communicate with each other to form a cooling flow path through which cooling water and the like flow.

  The oxidant electrode 31, the fuel 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 oxidant electrode 31 and the fuel 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 oxidant electrode 31 include a platinum catalyst, a platinum / ruthenium catalyst, and a cobalt catalyst. Examples of the catalyst in the fuel 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.

  FIG. 3 shows an example of a fuel cell 40 (cell stack) composed of a plurality of unit cells including the separator 20 and the membrane-electrode assembly 5. The fuel cell 40 communicates with an oxidant supply port 171 and an exhaust port 172 that communicate with the oxidant flow channel, a fuel supply port 181 and an exhaust port 182 that communicate with the fuel channel, and a cooling channel. A cooling water supply port 191 and a discharge port 192.

  In this embodiment, a separator with a gasket for a fuel cell is manufactured. The separator 30 with a fuel cell gasket includes a separator 20 and a gasket 12 laminated on the separator 20. In the separator with a gasket for a fuel cell according to the present embodiment, the hydrophilicity of the surface of the separator 20 is sufficiently high. Usually, when a gasket is laminated on the separator 20, components derived from the material for forming the gasket are likely to adhere to the surface of the separator 20. For this reason, even if the separator 20 is subjected to a hydrophilization treatment, the above-described components interfere with the action of the hydrophilization treatment, and thus the hydrophilicity of the separator 20 may not be sufficiently improved. However, in this embodiment, after the gasket is laminated on the separator 20, the separator 20 and the gasket are blasted. Therefore, the amount of impurities on the surface of the separator 20 is reduced, and thereby the amount of components derived from the material for forming the gasket on the surface of the separator 20 is reduced. For this reason, in the separator 30 with a gasket for a fuel cell according to the present embodiment, the surface of the separator 20 exhibits excellent hydrophilicity even though the gasket 12 is previously laminated on the separator 20.

  Hereinafter, the manufacturing method of the separator with the gasket for fuel cells according to the present embodiment will be described in more detail.

  In the present embodiment, a separator molding material (hereinafter referred to as a molding material) used for manufacturing a separator contains graphite and a thermosetting resin component.

  The graphite particles in the molding material are used for improving the conductivity of the separator by reducing the electrical specific resistance of the separator. The ratio of the graphite particles in the molding material is preferably in the range of 70 to 90% by mass with respect to the total solid content in the molding material. When the ratio of the graphite particles is 70% by mass or more, the separator is provided with sufficiently excellent conductivity. When the ratio is 90% by mass or less, the molding material has sufficiently excellent moldability. As well as being imparted, the separator is provided with sufficiently excellent gas permeability. The ratio of the graphite particles is more preferably in the range of 70% by mass to 81% by mass.

  If it shows high electroconductivity, various graphite particles will be used without a restriction | limiting. For example, 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, quiche graphite Appropriate graphite particles such as expanded graphite are used. Such various graphite particles are used singly or in combination.

  The graphite particles may be either artificial graphite powder or 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.

  The graphite particles are preferably purified regardless of whether they are natural graphite powder or artificial graphite powder. In this case, since the contents of ash and ionic impurities in the graphite particles are reduced, the elution of impurities from the separator is suppressed. The ash content in the graphite particles is particularly preferably 0.05% by mass or less. When this ash content exceeds 0.05 mass%, there exists a possibility that the characteristic fall of a fuel cell provided with a separator may be caused.

  The average particle size of the graphite particles is preferably in the range of 10 to 100 μm. When the average particle size is 10 μm or more, the moldability of the molding material becomes excellent, and when the average particle size is 100 μm or less, the surface smoothness of the separator is further improved. In order to particularly improve the moldability of the molding material, the average particle size is preferably 30 μm or more. Moreover, in order that the surface smoothness of a separator improves especially and arithmetic mean height Sa of the surface of a separator may become the range of 0.4-1.2 micrometers as it mentions later, the said average particle diameter is 70 micrometers or less. It is preferable.

  In particular, when a thin separator is obtained, 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 the 100 mesh sieve, graphite particles with a large particle size will be mixed in the molding material, especially when the molding material is molded into a thin sheet. The nature will decline.

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

  Regarding the reduction of the anisotropy of the separator, the contact resistance ratio between the flow direction of the molding material at the time of molding and the direction orthogonal to the flow direction in the separator is preferably 2 or less. .

  In particular, the graphite particles preferably have two or more particle size distributions. That is, it is preferable that the graphite particles include two or more kinds of particle groups having different average particle diameters. In this case, it is particularly preferable that the graphite particles include 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, a group of particles having a large average particle diameter has a small surface area, so that the molding material can be kneaded even with a small amount of resin. Further, the particle group having a small average particle size improves the contact property between the graphite particles and improves the strength of the molded product. Thereby, the improvement of performance, such as the improvement of the bulk density of a separator, the improvement of electroconductivity, the improvement of gas impermeability, the improvement of an intensity | 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. In particular, the mixing ratio of the former to the latter is 40:60 to 90:10, particularly 65. : It is preferable that it is 35-85: 15.

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

  The thermosetting resin component preferably contains a thermosetting resin containing at least one of an epoxy resin and a 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. In the thermosetting resin component, a curing agent and a catalyst (curing accelerator) used as necessary are also included. The content of the thermosetting resin component in the molding material is in the range of 15 to 28% by mass with respect to the total solid content.

  It is preferable that content of the epoxy resin and thermosetting phenol resin with respect to the whole thermosetting resin in a thermosetting resin component exists in the range of 50-100 mass%. It is particularly preferable that the thermosetting resin is 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 a material decreases and the handleability of the molding material at the time of shaping | molding improves. When the melting point is less than 70 ° C., aggregation tends to occur in the molding material, and the handleability may be reduced. Also, if a resin having a low melt viscosity is selected as the epoxy resin, the molding material and the separator can be highly filled with graphite particles while maintaining good moldability of the moldable composition. Become. 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, a component comprising an ortho cresol novolac type epoxy resin as an epoxy resin, or an ortho cresol novolac type epoxy resin, and at least one selected from a bisphenol type epoxy resin, a biphenyl type epoxy resin, and a phenol aralkyl type epoxy resin having a biphenylene skeleton. Are preferably used. The ratio of these components to the total amount of the thermosetting resin in the molding material is preferably in the range of 50 to 100% by mass.

  When the ortho-cresol novolac type epoxy resin is an essential component, the molding material is excellent in moldability and the separator is excellent in heat resistance. In addition, the manufacturing cost can be reduced. The ratio of the ortho-cresol novolac type epoxy resin to the entire epoxy resin is preferably in the range of 50 to 100% by mass, particularly from the viewpoint of improving the moldability, improving the heat resistance of the separator, and reducing the manufacturing cost. It is preferable to be in the range of -70% by mass.

  It is also preferable that at least one selected from a bisphenol type epoxy resin, a biphenyl type epoxy resin, and a phenol aralkyl type epoxy resin having a biphenylene skeleton is used in combination with the orthocresol novolac type epoxy resin. In this case, the melt viscosity of the molding material is further reduced, and the toughness of the separator is improved particularly when a thin separator is produced.

  In particular, when a bisphenol F type epoxy resin is used, the viscosity of the molding material is reduced, and a molding material having particularly high moldability can be obtained. In this case, the ratio of the bisphenol F type epoxy resin to the whole epoxy resin is preferably in the range of 30 to 50% by mass.

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

  In addition, when a phenol aralkyl type epoxy resin having a biphenylene skeleton is used, the strength and toughness of the separator are further improved, and the hygroscopicity of the separator is further reduced. For this reason, the mechanical properties, conductivity, and stability of the properties during long-term use of the separator are excellent. In this case, the ratio of the phenol aralkyl type epoxy resin having a biphenylene skeleton to the whole epoxy resin is preferably in the range of 30 to 50% by mass.

  An ortho-cresol novolac type epoxy resin is used as the epoxy resin, or when at least one selected from a bisphenol type epoxy resin, a biphenyl type epoxy resin, and a phenol aralkyl type epoxy resin having a biphenylene skeleton is used, in addition to these. These thermosetting resins may be used in combination. For example, one or more kinds of resins selected from epoxy resins other than the listed epoxy resins, thermosetting phenol resins, vinyl ester resins, polyimide resins, unsaturated polyester resins, diallyl phthalate 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. In addition, it is also suitable to use a polyimide resin as the thermosetting resin in that it contributes to the improvement of the heat resistance and acid resistance of the separator. As such a polyimide resin, bismaleimide resin is particularly preferable. In particular, when 4,4-diaminodiphenyl bismaleimide is used, the heat resistance of the separator is further improved.

  When an epoxy resin is used, the molding material contains an epoxy resin curing agent. Although it will not specifically limit if a hardening | curing agent has the capability to harden the epoxy resin which a molding material contains, It is preferable to make a phenol type compound into an essential component. Examples of the phenol compound include various polyphenol resins such as a phenol novolak resin, a cresol novolak resin, a phenol aralkyl resin, and a naphthol aralkyl resin.

  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. In particular, the equivalent ratio of the epoxy resin to the phenolic compound is preferably in the range of 0.8 to 1.2.

  When other curing agents other than the phenolic compound are used in combination, the other curing agent is preferably a non-amine compound. In this case, the separator is maintained in a high electrical conductivity, and the fuel cell. The poisoning of the catalyst is suppressed. Further, it is preferable that an acid anhydride compound is not used as a curing agent. When an acid anhydride compound is used, it will hydrolyze in an acidic environment such as sulfuric acid, causing a decrease in the electrical conductivity of the separator or increasing the elution of impurities from the separator. There is a fear.

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

  As the thermosetting resin, other resins than the epoxy resin and the thermosetting phenol resin may be used in combination. For example, one or a plurality of resins selected from polyimide resins, melamine resins, unsaturated polyester resins, diallyl phthalate resins, and the like are used. However, it is preferable that a resin containing an ester bond is not used because it may hydrolyze in an acid resistant environment.

  A polyimide resin is also suitable as a thermosetting resin in that it contributes to improving the heat resistance and acid resistance of the separator. Examples of such a polyimide resin include bismaleimide resin. Specific examples thereof include 4,4-diaminodiphenyl bismaleimide. When such other resins are used in combination, the heat resistance of the separator is further increased.

  As described above, the thermosetting resin component contains 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.

  In particular, as a catalyst, the weight loss is 5% or less 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 It is preferable to use a substituted imidazole having a hydrocarbon group. When such a substituted imidazole is used, the storage stability of a liquid (varnish or slurry) molding material, the volatility when a sheet is formed from the molding material, and the smoothness of the sheet are particularly good. Become. 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. Of these, 2-undecylimidazole and 2-heptadecylimidazole are preferred. These compounds are used alone or in combination of two or more.

  As the catalyst, other compounds may be used in combination with the substituted imidazole as described above. In particular, when a phosphorus compound (organic phosphine) such as triphenylphosphine is used in combination, elution of chlorine ions from the separator is further suppressed.

  The content of the catalyst in the molding material is appropriately adjusted, whereby the molding hardening time of the molding material is appropriately adjusted. In particular, the content of the catalyst in the molding material 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.

  The molding material may further contain an internal mold release agent. As the internal mold release agent, an appropriate one is used, but an internal mold release agent that separates in phase without being incompatible with the thermosetting resin and the curing agent in the molding material is particularly preferable at 120 to 190 ° C. As such an internal mold 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 hardener in the molding process of the molding material, so that the mold release improving effect is satisfactorily exhibited.

  The amount of the internal mold release agent used is appropriately set in consideration of the complexity of the separator shape, 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 molding material is preferably in the range of 0.1 to 2.5 mass%. When this ratio is 0.1% by mass or more, sufficient release properties are exhibited at the time of molding the mold, and when this ratio is 2.5% by mass or less, the hydrophilic property on the surface of the separator is inhibited by the internal mold 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 molding material may contain additives such as a coupling agent as necessary. Examples of the coupling agent include silicon-based silane compounds, titanate-based, and aluminum-based coupling agents. In particular, an epoxy 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. The amount of the epoxy run coupling agent used is preferably in the range of 0.5 to 1.5 mass% with respect to the entire solid content of the molding material. In this range, bleeding of the coupling agent to the separator surface is sufficiently suppressed.

  The molding material may contain a solvent. In particular, when a thin separator is produced, the molding material may be prepared in a liquid form (including varnish and slurry) by containing a solvent. As the solvent, for example, polar solvents such as methyl ethyl ketone, methoxypropanol, N, N-dimethylformamide, dimethyl sulfoxide are preferable. Only one type of solvent may be used, or two or more types may be used in combination. The amount of the solvent used is appropriately set in consideration of moldability when producing a sheet-like separator from the molding material. In particular, the amount of solvent used is preferably set so that the viscosity of the molding material is in the range of 1000 to 5000 cP. In addition, a solvent should just be used as needed, and if a molding material is prepared in a liquid state by using liquid resin as a thermosetting resin etc., a solvent does not need to be used.

  The content of ionic impurities in the separator is preferably small, and in particular, the sodium content is preferably 5 ppm or less and the chlorine content is 5 ppm or less in terms of mass ratio. For this purpose, the content of ionic impurities in the molding material is preferably low, and in particular, the sodium content is preferably 5 ppm or less and the chlorine content is 5 ppm or less in terms of mass ratio to the total solid content of the molding material. In this case, elution of ionic impurities from the separator is suppressed, and deterioration of characteristics such as a decrease in starting voltage of the fuel cell due to the elution of impurities is suppressed.

  In order to reduce the content of ionic impurities in the separator and the molding material as described above, the ionic impurities of each component such as thermosetting resin, curing agent, graphite, and other additives constituting the molding material. In particular, the sodium content is preferably 5 ppm or less and the chlorine content is 5 ppm or less in terms of mass ratio to each component.

  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 molding material is preferably prepared so that the TOC (total organic carbon) of the separator formed from the molding material is 100 ppm or less.

  The TOC is a numerical value measured using an aqueous solution after the separator is put into ion-exchanged water at a rate of 100 ml of ion-exchanged water with respect to 10 g of the separator and treated at 90 ° C. for 50 hours. 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 CO2 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.

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

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

  The molding material is prepared by mixing the above-described components by an appropriate method and kneading and granulating as necessary.

  A separator is obtained by molding the molding material.

  When a thin separator is obtained from a molding material prepared in the form of a varnish, the molding material particularly has a particle size that passes through a 100 mesh sieve (aperture 150 μm) and has an average particle size of 30 to 70 μm. Particles; an epoxy resin component comprising an ortho-cresol novolac type epoxy resin, or consisting of this ortho-cresol novolac type epoxy resin and at least one selected from a bisphenol type epoxy resin and a phenol aralkyl type epoxy resin having a biphenylene skeleton; a curing agent A phenol resin; and 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, the weight loss is 5% or less, It is preferable to contain a substituted imidazole having a hydrocarbon group at the 2-position. In this case, first, the molding material is molded into a sheet shape to obtain a separator molding sheet (molding sheet). The molding material is molded into a sheet by, for example, casting (progressive) molding. In this molding, a plurality of types of film thickness adjusting means can be applied. The casting method to which such a plurality of types of film thickness adjusting means are applied is realized by, for example, a multi-coater that has already been put into practical use. As a film thickness adjusting means for casting, it is preferable to use at least one of a doctor knife and a wire bar together with a slit die.

  The thickness of the molding sheet 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. If the thickness of the molding sheet is 0.5 mm or less, the separator can be made thin and light, and the cost can be reduced sufficiently. Especially when the thickness is 0.3 mm or less, a solvent is used. The remaining solvent in the molding sheet is effectively suppressed. Further, when the thickness is less than 0.05 mm, the advantage in producing the separator is not sufficiently exhibited, and in consideration of moldability, the thickness is preferably 0.1 mm or more.

  The molding sheet is made into a semi-cured (B stage) state by drying along with casting, and is cut (cut) or punched into a predetermined plane dimension as necessary, and then molded on both sides. The convex portion (rib) 21 is formed, and the gas supply / discharge groove 2 is formed between the convex portions (rib) 21. Thereby, a separator is obtained. When this separator is formed in a corrugated plate shape and the gas supply / discharge groove 2 on the other surface is formed on the back side of the convex portion 21 on one surface, a plurality of convex portions are formed on both surfaces while being thin. A separator having the (rib) 21 and the gas supply / discharge groove 2 between the convex portions (ribs) 21 is obtained.

  In producing the separator, the separator may be produced from one molding sheet, or the separator may be produced from a plurality of molding sheets. By using the molding sheet in this manner, a thin separator can be manufactured, and particularly a separator having a thickness in the range of 0.2 to 1.0 mm can be manufactured. In addition, by using a molding sheet when manufacturing the separator, it becomes easy to form and arrange the molding material thinly and uniformly even when a thin separator is manufactured, and the moldability and thickness accuracy are improved. .

  In addition, at the time of preparation of a separator, the sheet | seat for shaping | molding and a suitable electroconductive base material may be laminated | stacked. When a conductive substrate is used, the mechanical strength of the separator is improved. When a conductive substrate is used, for example, a laminate in which molding sheets (including a laminate of a plurality of molding sheets) are laminated on both sides of the conductive substrate is compression / thermosetting, Alternatively, a laminate in which a conductive base material is laminated on both sides of a molding sheet (including a laminate of a plurality of molding sheets) is compression / thermosetting molded.

  Examples of the conductive substrate include carbon paper, carbon prepreg, carbon felt and the like. These conductive substrates may contain substrate components such as glass and resin as long as the conductivity is not impaired. The thickness of the conductive substrate is preferably in the range of 0.03 to 0.5 mm, and more preferably in the range of 0.05 to 0.2 mm.

  The varnish-like molding material is useful not only when a thin separator is produced through the production of a molding sheet, but also when the separator is produced without producing a molding sheet. In this case, the storage stability and moldability of the molding material are excellent.

  In order to obtain a separator from a molding material (including a molding sheet formed from the molding material), it is preferable to employ compression molding under reduced pressure or vacuum conditions. By producing a separator from a molding material having the above composition by compression molding under reduced pressure or under vacuum, a separator with little density variation and high thickness accuracy can be obtained.

  In compression molding under reduced pressure or vacuum conditions, after the molding material is filled in the mold, the inside of the mold or around the mold including the mold is decompressed, and the inside of the mold is decompressed. Maintained under vacuum or vacuum conditions. In this state, the mold is heated and pressed with a predetermined compression force, whereby compression molding is performed. Thereafter, the mold is cooled to room temperature by a cooling device, and then the separator is taken out from the mold.

  In this compression molding, the degree of vacuum around the mold or around the mold including the inside of the mold is preferably 80 kPa or more, and particularly preferably 95 kPa or more. The upper limit of the degree of vacuum is not particularly limited, but is practically up to 100 kPa.

  The heating temperature and compression pressure at the time of compression molding depend on the composition of the molding material, the presence and type of the conductive base material, the molding thickness, etc., for example, the range of heating temperature 120 to 190 ° C., the range of compression pressure 1 to 40 MPa It is preferable that The molding time is preferably set in the range of 15 seconds to 600 seconds.

  In compression molding under reduced pressure or vacuum conditions, a molding apparatus having an arbitrary structure is used. For example, a molding apparatus including a mold having a minute opening for vacuum suction is used. Moreover, a molding apparatus including a molding machine having a mechanism capable of vacuum suction may be used. In particular, when the molding machine is equipped with a mechanism capable of vacuum suction, it is preferable in that the degree of freedom in designing the mold is increased and the maintenance of the mold is facilitated. An example of such a molding machine is a vacuum air venting rubber molding machine manufactured by Otake Machinery Co., Ltd. On the other hand, when a mold having a small hole for vacuum suction is used, there is an advantage that the decompression time can be shortened.

  As a compression method in compression molding under a reduced pressure condition or a vacuum condition, a mechanical compression method, a compression method using a mechanism using hydraulic pressure, pneumatic pressure, water pressure, or the like is employed. The molding time required for compression molding is set as appropriate, but about 1 minute to 5 minutes is sufficient even when the mold cooling time is included.

  A mold used for compression molding includes, for example, a heating unit and includes a lower mold and an upper mold. A concave portion corresponding to the convex portion of the separator is formed on both the lower die and the upper die. When a molding machine having a vacuum sucking mechanism is used, for example, the upper mold and the lower mold are first preheated in a state where the mold is opened, and then the molding material is formed on the lower mold from a sieve or the like. Falls and is placed. As a result, the molding material is uniformly placed on the lower mold. When the molding sheet is formed from the molding material, the molding sheet, or the molding sheet and the conductive substrate are placed on the lower mold. Subsequently, the vacuum chamber containing the mold is closed, and the inside of the vacuum chamber is decompressed. When the inside of the vacuum chamber reaches a predetermined degree of vacuum, the upper mold is lowered toward the lower mold and the mold is clamped. As a result, the molding material is heated and compressed by a predetermined mold temperature and compression force, and a separator is formed in the mold. Then, after a metal mold | die is cooled to normal temperature with a cooling device, a separator is taken out from this metal mold | die.

  When a mold having a minute opening for vacuum suction is used, for example, the upper mold and the lower mold are first preheated in a state where the mold is opened, and then the molding material is placed on the lower mold. Dropped from the sieve. As a result, the molding material is uniformly placed on the lower mold. When the molding sheet is formed from the molding material, the molding sheet, or the molding sheet and the conductive substrate are placed on the lower mold. Subsequently, the upper mold is lowered toward the lower mold and the mold is clamped, and the inside of the mold is vacuumed through the opening of the mold to reduce the pressure in the mold. In this state, the molding material is heated and compressed by a predetermined mold temperature and compression force, and a separator is formed in the mold. After the mold is cooled to room temperature by a cooling device, the separator is taken out from the mold.

  Furthermore, it is preferable that the separator obtained by compression molding is subjected to heat treatment. The heating temperature in this heat treatment is preferably in the range of 150 to 180 ° C., and the heating time is preferably in the range of 30 seconds to 1 hour.

  The thickness of the separator is preferably 3 mm or less. In particular, it is preferable that the thickness dimension of the separator having the largest thickness dimension is in the range of 0.5 to 3.0 mm, and the thickness dimension of the smallest thickness dimension is in the range of 0.3 to 0.7 mm. In producing such a thin separator, according to this embodiment, the separator is produced from a highly moldable molding material having the above composition by compression molding under reduced pressure or vacuum conditions. As a result, the void is quickly removed from the molding material during molding, so that a separator with high thickness accuracy can be obtained.

The density variation width of the separator is preferably 0.02 g / cm ³ or less. The density variation width is the difference between the density value at the highest density part and the density value at the lowest density part in the separator. According to this embodiment, a separator is produced from a highly moldable molding material having the above composition by compression molding under reduced pressure or vacuum conditions, so that voids are formed from the molding material during molding. Get rid of promptly. As a result, the molding material becomes uniform, and a separator having a small density variation width can be manufactured. Thus, when the density variation of the separator is 0.02 g / cm ³ or less, even if the separator is thin, cracks are less likely to occur and productivity is improved, and the electrical conductivity, gas permeability and mechanical properties of the separator are improved. The mechanical strength is improved. The density variation width of the separator is more preferably 0.015 g / cm ³ or less, and further preferably 0.01 g / cm ³ or less.

  After the separator is manufactured, a gasket is laminated on the separator before the blasting process is performed on the separator. When the unit cell includes a cathode-side separator and an anode-side separator as separators, the gasket includes a gasket that is stacked on the first surface of the cathode-side separator, a gasket that is stacked on the second surface of the cathode-side separator, and a cathode. A gasket that is overlaid on the first side of the side separator and a gasket that is overlaid on the second side of the cathode side separator. The gasket provided in the fuel cell separator with a gasket may be one or more selected from the above-mentioned four types of gaskets.

  FIG. 1A shows an example of a separator 30 (31) with a gasket for a fuel cell that includes a cathode-side separator 21 as the separator 20. FIG. 1B shows an example of a fuel cell gasketed separator 30 (32) provided with an anode side separator 22 as the separator 20. A separator 31 with a gasket for a fuel cell shown in FIG. 1A includes a cathode-side separator 21, a gasket 12 superimposed on the first surface of the cathode-side separator 21, and a second surface of the cathode-side separator 2120. And a gasket 12 stacked on the surface. Moreover, the separator 32 with a gasket for fuel cells shown in FIG. 1B includes an anode-side separator 22 and a gasket 12 that is stacked on the first surface of the anode-side separator 22.

  Gaskets include, 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). It is formed from a rubber material selected from chloroprene rubber, acrylic rubber, fluorine rubber and the like. This rubber material may contain a tackifier.

  When the gasket is laminated on the separator, for example, a gasket formed in a sheet shape or a plate shape in advance is bonded or bonded to the separator.

  Further, the gasket may be formed by molding a material for forming the gasket on the surface of the separator. In this case, for example, a gasket may be formed on the separator by applying a material for forming a gasket on the surface of the separator by a screen printing method or the like and subsequently curing the material. For example, an unvulcanized rubber material is applied to a predetermined position on the surface of the separator by screen printing or the like, and a coating film of this rubber material is vulcanized to form a gasket having a desired shape at a predetermined position on the surface of the separator. May be 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 is easily laminated even on the thin separator.

  In addition, the separator is set in a mold, and an unvulcanized rubber material is injected into a predetermined position on the surface of the separator, and the rubber material is heated and vulcanized to vulcanize the separator. A gasket having a desired shape may be formed at a predetermined position on the surface. Thus, when forming a gasket by metal mold | die shaping | molding, shaping | molding methods, such as compression molding and injection molding, can be employ | adopted besides transfer molding.

  When the gasket is formed by molding, it is preferable that the gasket is further heated after the separator on which the gasket is laminated is taken out of the mold. In this case, the curing reaction of the gasket further proceeds, thereby suppressing the elution of impurities from the gasket.

  After the gasket is laminated on the separator, the separator is blasted. For this reason, even when a component derived from the material for forming the gasket adheres to the separator when the gasket is stacked on the separator, the component is removed from the separator by blasting. For this reason, it is suppressed that the component derived from the material for forming a gasket inhibits the effect | action of the surface treatment for the hydrophilization mentioned later. Thereby, the favorable hydrophilicity of the surface of a separator is maintained.

  By blasting, the surface skin layer of the separator is removed and the surface roughness of the separator is adjusted. The arithmetic mean height Sa (arithmetic mean height of the scale limited surface; Sa) defined by ISO 25178-2: 2012 is adjusted to a range of 0.4 μm to 1.2 μm by blasting. It is preferred that In this case, the hydrophilicity of the separator surface is particularly improved by the hydrophilization treatment described later. Further, when the gasket is stacked on the separator, leakage between the separator and the gasket is suppressed. The arithmetic average height Sa on the surface of the separator is more preferably in the range of 0.6 to 1.0 μm.

  In particular, the arithmetic average height Sa of the surface on which the groove for flowing the fuel gas or the groove for flowing the oxidant gas is formed in the separator by blasting is 0.4 μm or more and 1.2 μm or less. It is preferable that the range is adjusted. That is, in the present embodiment, the arithmetic average height Sa of the first surface of the cathode side separator 21 and the arithmetic average height Sa of the first surface of the anode side separator 22 are 0.4 μm or more and 1.2 μm or less. It is preferable to adjust to the range. In this case, the skin layer is sufficiently removed from the separator. Further, since the hydrophilicity of the separator surface is particularly improved, it is possible to effectively prevent the fuel gas and oxidant gas flow paths from being blocked by water droplets. This arithmetic average height Sa is particularly preferably in the range of 0.8 to 1.2 μm.

  In addition, the arithmetic average height Sa of the surface (hereinafter referred to as a water channel surface) opposite to the surface on which the groove for allowing the fuel gas or the oxidant gas to flow in the separator is 0.4 μm or more and 1.2 μm. It is preferable to adjust to the following range. This water channel surface is a surface constituting a flow path for circulating cooling water. In the present embodiment, the second surface of the anode-side separator 22 and the second surface of the cathode-side separator 21 are water channel surfaces. is there. When the arithmetic average height Sa of the water channel surface is adjusted as described above, leakage of cooling water from between the water channel surface and the gasket when the gasket is overlapped on the water channel surface is effectively suppressed. In particular, when the fuel cell gasket separator is not provided with a gasket that overlaps the water channel surface, and the unit cell is formed from this fuel cell gasket separator, the gasket is overlapped on the water channel surface. Leakage of cooling water from between is effectively suppressed. For this reason, in the present embodiment, it is particularly preferable that the arithmetic average height Sa of the second surface of the anode-side separator 22 is adjusted as described above. It is more preferable if the arithmetic mean height Sa of the waterway surface is in the range of 0.5 to 0.7 μm.

  Further, when the blasting process is performed on the separator, the blasting process may be performed on the gasket at the same time. In this case, it is not necessary to mask the gasket, which increases the processing efficiency of the blasting process.

  In addition, by performing blasting on the gasket, the arithmetic mean height Sa (arithmetical mean height of the scale limited surface; Sa) defined by ISO 25178-2: 2012 is 0.3. It is preferable to adjust to a range of ~ 0.6 μm.

  The arithmetic average height Sa of the separator and gasket is derived from the measurement result of the three-dimensional surface properties of the separator and gasket by a laser microscope. As the laser microscope, for example, a 3D measurement laser microscope (model number OLS4000) manufactured by Shimadzu Corporation can be used.

  When evaluating the surface roughness of the separator and gasket as described above, the three-dimensional surface property is measured by a laser microscope, and the arithmetic average height Sa derived from the result is used. Compared to the case of measuring a two-dimensional contour curve, a finer and more accurate shape of the separator and the gasket is measured. Since the surface of the separator has very fine irregularities, the surface property of the separator can be specified more accurately by using the arithmetic average height Sa based on the measurement result by the laser microscope. Also, in setting the blasting conditions such as the grain size of the abrasive grains, by investigating the relationship between the blasting conditions and the arithmetic average height Sa based on the measurement result by the laser microscope, more appropriate blasting can be performed. It is possible to set conditions. In addition, since the measurement with a laser microscope is a non-contact measurement, even when measuring the surface properties of a soft gasket, it is accurately measured, and therefore the arithmetic average height Sa of the gasket is accurately derived. Is done.

  It is preferable to employ wet blasting as the blasting applied to the separator and the gasket. In this case, variations are less likely to occur in the degree of blasting and the roughness of the surface of the separator and gasket after blasting. For this reason, the stability of the quality of the separator with a gasket for a fuel cell is increased.

  The material of the abrasive grains used for the blast treatment is not particularly limited, and examples thereof include alumina and silicon carbide. Moreover, although the average particle diameter of an abrasive grain is set suitably, it is the range of 3-200 micrometers, for example.

  In particular, the average grain size of the abrasive grains is preferably in the range of 7.8 to 43.6 μm. Thus, when the average particle size of the abrasive grains is 43.6 μm or less, the variation of the arithmetic average height Sa of the surface of the separator and the gasket with respect to the variation of the spray pressure of the slurry during the blasting process is reduced. For this reason, the arithmetic average height Sa on the surface of the separator is stably controlled by the blast treatment. In addition, the graphite particles are prevented from dropping from the separator due to the impact of the blast treatment, and therefore the contact resistance of the separator is kept low. Furthermore, such abrasive grains can form very fine irregularities on the surfaces of the separator and the gasket, and can also form irregularities on the graphite particles exposed on the surface of the separator. Even if the separator has fine irregularities in this way, the arithmetic average height Sa of the separator and the gasket can be accurately derived from the measurement result by the laser microscope. Further, when the average grain size of the abrasive grains is 7.8 μm or more, the skin layer of the separator is sufficiently removed by the blasting process, and thus the contact resistance of the separator is sufficiently lowered.

  The average particle size of the abrasive grains is the particle size (d50) at the 50% cumulative height.

  When the blasting process is performed on the separator and the gasket, the blasting process may be performed simultaneously on the first surface and the second surface of the separator. That is, when wet blasting is employed, slurry containing abrasive grains may be simultaneously sprayed on the first surface and the second surface of the separator. In this case, the efficiency of the blasting process is improved.

  When wet blasting is performed on the separator and the gasket, it is preferable that the metal component is removed from the slurry containing abrasive grains using a magnet and then wet blasting is performed using this slurry. . Abrasive grains used for blasting may contain metal components as impurities. Moreover, a metal component may mix in the slurry containing an abrasive grain at the time of a blasting process. When a slurry containing such a metal component is used for wet blasting, the metal component adheres to the surfaces of the separator and the gasket. However, if the metal component is removed from the slurry as described above and then wet blasting is performed using this slurry, the metal component is less likely to adhere to the separator during blasting. In the wet blast treatment, when the slurry is repeatedly used while being circulated, it is preferable that the slurry is used again in the wet blast treatment after the metal component is removed from the slurry used in the wet blast treatment.

  The separator after the blast treatment is subjected to a hydrophilic treatment. In addition, it is preferable that after a blasting process and before a hydrophilic treatment, the separator and the gasket are subjected to a cleaning process or further subjected to a drying process. In the cleaning process, for example, the separator and the gasket are cleaned with ion exchange water or the like. In the drying process, the separator and the gasket are preferably air-dried by air blow or the like. In this case, air blow by normal temperature or warm air may be adopted as necessary, or air blow by warm air may be additionally performed after air blow at normal temperature. In the drying process, the separator and the gasket are allowed to stand in a desiccator containing a desiccant such as silica gel, the separator and the gasket are allowed to stand in a dryer having a temperature of room temperature or higher (for example, 50 ° C.), A method of removing moisture from the separator and the gasket using a vacuum dryer may be employed. It is preferable that the separator and the gasket are dried by this drying treatment until the moisture absorption rate is 0.1% or less.

  The hydrophilic treatment is a treatment for improving the hydrophilicity of the separator surface. Thus, when high hydrophilicity is imparted to the surface of the separator, the grooves 2 in the separator are not easily blocked by condensed water. For this reason, the high power generation efficiency of the fuel cell is maintained for a long time.

The hydrophilic treatment is not particularly limited as long as it can improve the hydrophilicity of the separator surface. Hydrophilic treatment includes, for example, plasma treatment for exposing the separator to plasma, ozone gas treatment for exposing the separator to ozone gas, SO ₃ treatment for exposing the separator to SO ₃ , fluorine treatment for exposing the separator to a gas containing fluorine, silicon compound Alternatively, one or more are selected from flame treatment in which a gas containing a modifier compound containing an aluminum compound is burned and sprayed onto the separator, and ozone water treatment in which ozone water is brought into contact with the separator. In particular, it is preferable to employ plasma treatment.

  As the plasma treatment, it is preferable to perform an atmospheric pressure plasma treatment, and it is particularly preferable to perform a plasma treatment by a remote method. In this remote atmospheric pressure plasma processing, for example, a plasma processing apparatus including a discharge space having an outlet and a discharge electrode for generating an electric field in the discharge space is used. In this plasma processing apparatus, a plasma generating gas is supplied to the discharge space, the pressure in the discharge space is maintained near atmospheric pressure, and a voltage is applied between the discharge electrodes to discharge the discharge space. When generated, plasma is generated in the discharge space. The gas stream containing the plasma is blown out from the outlet and blown onto the molded body, whereby the molded body is subjected to plasma treatment. Examples of such a plasma processing apparatus include the APT series manufactured by Sekisui Chemical Co., Ltd., but an appropriate plasma processing apparatus provided by Panasonic Corporation, Yamato Material Corporation, or the like may be used.

  When such a remote-type plasma treatment is employed, plasma is sprayed toward the surface of the molded body, so that the inner surface of the groove of the molded body is sufficiently processed. Further, the molded body is not exposed to electric discharge during the plasma treatment, and therefore, the molded body is hardly damaged during the plasma treatment.

  The atmospheric pressure plasma treatment is performed under conditions appropriately set so that desired hydrophilicity is imparted to the surface of the molded body. The plasma generating gas in the atmospheric pressure plasma treatment is preferably nitrogen gas, and particularly preferably the oxygen content in the nitrogen gas is 2000 ppm or less. In this case, particularly high hydrophilicity is imparted to the separator by the atmospheric pressure plasma treatment.

  Further, when the equivalent ratio of the epoxy resin to the phenolic compound in the molding material is in the range of 0.8 to 1.2, the hydrophilicity of the surface of the separator is particularly increased by the plasma treatment.

  The atmospheric pressure plasma treatment is preferably performed under conditions in which the temperature of the molded body and the ambient temperature are adjusted so that condensation does not occur on the surface of the molded body. In this case, the consumption of plasma due to water droplets adhering to the surface of the compact is suppressed, and the processing efficiency is improved. As described above, the temperature of the molded body is preferably equal to or higher than the temperature at which dew condensation does not occur on the surface of the molded body (dew point temperature), and is preferably 70 ° C. or lower for stable atmospheric pressure plasma treatment. In order to stabilize the atmospheric pressure plasma treatment, it is also important to keep the temperature of the compact and the ambient temperature constant. In adjusting the atmospheric temperature, the temperature of the plasma unit of the plasma processing apparatus is usually adjusted. Depending on the configuration of the plasma processing apparatus, the temperature of the stage that supports the compact during plasma processing is adjusted.

  In the atmospheric pressure plasma processing, plasma processing other than the remote method, for example, direct plasma processing may be employed.

  The molded product after the plasma treatment may be left in the air as it is, but is subjected to a water contact treatment in which the molded product is brought into contact with water by immersing the molded product in water such as ion exchange water. It is preferable.

  When surface treatment including atmospheric pressure plasma treatment is performed on the molded body in this way, the hydrophilicity of the surface of the molded body is improved and this high hydrophilicity is maintained for a long period of time. The details of the hydrophilization mechanism are unknown, but the hydroxyl groups are distributed on the surface of the molded body, so that moisture is adsorbed on the surface and functional groups are easily generated. Contaminants are removed from the surface to be in a highly active state, and hydrophilic functional groups such as hydroxyl groups are introduced into the activated surface to form many hydrophilic functional groups on the surface of the molded body, This is considered to contribute to the improvement of hydrophilicity.

  In particular, when the molded body is subjected to the drying treatment as described above prior to the plasma treatment, the atmospheric pressure plasma treatment on the molded body is not easily inhibited by water molecules, and the efficiency of the atmospheric pressure plasma treatment is improved.

In the atmospheric pressure plasma treatment, it is preferable that no arc is generated in the molded body. For this purpose, for example, it is desirable that a grounding device is installed in the electrode part of the plasma processing apparatus. Further, when the above-mentioned water contact treatment is performed on the molded body after the plasma processing, the surface of the molded body Hydrophilicity is further improved. Although the detailed mechanism is not clear, it is considered that the hydrophilicity of the surface of the molded body is improved due to the adsorption of water molecules on the surface of the molded body activated by the atmospheric pressure plasma treatment.

  The ozone gas treatment is performed by bringing ozone gas into contact with the surface of the separator. Examples of the gas containing ozone gas include a mixed gas containing ozone gas, oxygen gas, air, and the like. The ozone gas concentration in this surface treatment is not particularly limited. For example, even if it is a relatively low concentration in the range of 3.5 to 8.0% by volume, it is relatively high in the range of 8.0 to 14.0% by volume. It may be a concentration.

  The treatment temperature during this ozone gas treatment is preferably −50 ° C. or higher, more preferably 0 ° C. or higher, and even more preferably room temperature or higher. In consideration of the heat resistance limit of the separator, the treatment temperature is preferably 200 ° C. or less, more preferably 100 ° C. or less, further preferably 50 ° C. or less, and most preferably 30 ° C. or less. That is, the treatment temperature is preferably in the range of −50 ° C. to 200 ° C., more preferably in the range of 0 ° C. to 100 ° C., still more preferably in the range of 0 ° C. to 50 ° C., room temperature to 30 ° C. The range of is most preferable.

  The surface treatment time is preferably 1 second or longer, more preferably several seconds or longer, further preferably 10 seconds or longer, further preferably 0.1 hours or longer, and most preferably 0.2 hours or longer. . The treatment time is preferably 10 days or less, more preferably 10 hours or less, further preferably 5 hours or less, and particularly preferably 1 hour or less. Practical treatment time is preferably in the range of 1 to 4 hours at the longest, and is preferably 1 day or less even when the treatment is performed for a long time. For example, the range of 0.1 to 5 hours is preferable, and the range of 0.2 to 1 hour is more preferable.

  The atmospheric pressure during the ozone gas treatment is preferably near normal pressure. The atmospheric pressure may be lower or higher than normal pressure. Even in this case, the atmospheric pressure is preferably in the range of several hPa to 0.2 MPa.

  These treatment conditions are appropriately set so that a sufficient amount of ozone gas can be efficiently introduced into the separator and the separator is not deteriorated or burned by the ozone gas treatment.

  In the ozone gas treatment, ozone gas is brought into contact with the separator by an appropriate method. For example, ozone gas can be brought into contact with the separator by placing a separator in the processing container and supplying a gas containing ozone gas into the processing container.

  The separator subjected to the ozone gas treatment may be left in the air as it is, or may be washed with water and then dried.

  Such ozone gas treatment also improves the hydrophilicity of the separator surface. This is thought to be because hydrophilic functional groups are introduced into the surface of the separator due to ozone reacting on the surface of the separator by the surface treatment. Further, when the equivalent ratio of the epoxy resin to the phenolic compound in the molding material is in the range of 0.8 to 1.2, the hydrophilicity of the separator surface is particularly increased by the ozone gas treatment.

  Plasma treatment may be performed on the separator, followed by ozone gas treatment. In this case, first, contaminants are removed from the surface of the separator by plasma treatment, so that the surface of the separator becomes highly active. In addition, functional groups such as hydroxyl groups are introduced to the surface of the separator by this plasma treatment. If ozone gas treatment is subsequently applied to the separator, the ozone gas is more likely to react on the surface of the separator. For this reason, the hydrophilicity of the surface of the separator is maintained for a longer period. The plasma treatment performed before the ozone gas treatment is performed under conditions appropriately set so that a desired functional group can be introduced on the surface of the separator. For example, a model number “PDC210” manufactured by Yamato Material Co., Ltd. is used. Oxygen is used as the plasma generation gas, and the applied power is 150 to 500 W and the treatment time is 30 seconds to 10 minutes.

SO ₃ treatment is performed, for example, by contacting the gas (SO ₃ containing gas) containing SO ₃ on the surface of the separator. In this case, the SO ₃ -containing gas may contain only SO ₃ gas, or may contain SO ₃ gas, an inert gas such as nitrogen, argon or helium, oxygen, carbon dioxide gas or the like. The SO ₃ -containing gas may contain a gaseous Lewis base. The SO ₃ concentration in the SO ₃ -containing gas is not limited, but is preferably in the range of 0.1 to 80% by volume, more preferably 0.1 to 10% by volume, and 0.1 to 5% by volume. If it is more preferable.

In the SO ₃ treatment, for example, the separator is housed in an acid-resistant sealed container, and the state in which the SO ₃ -containing gas is circulated in the sealed container is maintained for a certain period of time. Further, the separator may be continuously passed through a chamber in which the SO ₃ -containing gas flows.

The treatment conditions for the SO ₃ treatment are appropriately set. For example, the flow rate per minute of only the SO ₃ gas in the SO ₃ -containing gas in the closed vessel is 0.5 to 5 times the volume of the closed vessel. Preferably, the flow rate is in the range of 0.01 to 10,000 ml / min. The treatment temperature is preferably in the range of 20 ° C to 100 ° C, more preferably 30 ° C to 80 ° C, and even more preferably 40 ° C to 70 ° C. The treatment time is preferably in the range of 0.1 seconds to 120 minutes, more preferably in the range of 1 to 60 minutes.

The separator is preferably subjected to a post treatment immediately after the SO ₃ treatment to remove sulfuric acid adhering to the surface of the separator. Examples of the post-treatment include washing with water, treatment with an aqueous solution of sodium bicarbonate and lime water, and the like. In particular, it is preferable that the post-treatment includes a treatment for washing the separator with an alkaline solution and a treatment for washing the separator with ion-exchanged water at 10 ° C. or higher.

When the SO ₃ treatment is performed, SO ₃ reacts with the surface of the separator to generate sulfonic acid groups, which are distributed on the surface of the separator, thereby improving the hydrophilicity of the separator. In particular, when a hydroxyl group in the SO ₃ treatment surface before the separator is distributed, the generation of sulfonic acid groups at the surface of the separator by SO ₃ process is significantly accelerated. Further, when the equivalent ratio of the epoxy resin to the phenolic compound in the molding material is in the range of 0.8 to 1.2, the hydrophilicity of the surface of the separator is particularly increased by the SO ₃ treatment.

In order to improve the hydrophilicity of the separator and to maintain the hydrophilicity for a long period of time, it is preferable that the amount of sulfur atoms on the surface of the separator is 0.1 atomic% by performing SO ₃ treatment. . The amount of sulfur atoms is measured by energy dispersive X-ray analysis. The value of the amount of sulfur atoms is more preferably in the range of 0.1 to 4.0 atomic percent, and even more preferably in the range of 2.0 to 4.0 atomic percent.

Plasma treatment may be applied to the separator, followed by SO ₃ treatment. In this case, first, contaminants are removed from the surface of the separator by plasma treatment, so that the surface of the separator becomes highly active. In addition, functional groups such as hydroxyl groups are introduced to the surface of the separator by this plasma treatment. If the separator is subsequently subjected to SO ₃ treatment, the SO ₃ gas is more likely to react on the surface of the separator. For this reason, the hydrophilicity of the surface of the separator is maintained for a longer period. The plasma treatment performed before the SO ₃ treatment is performed under conditions that are appropriately set so that a desired functional group can be introduced onto the surface of the separator. For example, a model number “PDC210” manufactured by Yamato Material Co., Ltd. is used. In addition, oxygen is used as the plasma generating gas, and the applied power is 150 to 500 W and the processing time is 30 seconds to 10 minutes.

Further, as a pretreatment for the SO ₃ treatment, the separator may be subjected to a heat treatment, a flame treatment, a corona treatment, an ultraviolet irradiation treatment, or the like.

  The fluorine treatment is performed, for example, by bringing a fluorine-containing gas (fluorine-containing gas) into contact with the surface of the separator. In this case, the fluorine-containing gas may contain only fluorine gas, or may contain fluorine gas, an inert gas such as nitrogen, argon, or helium, oxygen, carbon dioxide gas, or the like. The fluorine concentration in the fluorine-containing gas is not limited, but is preferably in the range of 0.01 to 100% by volume.

  In the fluorine treatment, for example, a separator is accommodated in a sealed container, and after the inside of the sealed container is depressurized, an inert gas such as nitrogen gas is supplied into the sealed container, and then fluorine gas is supplied into the sealed container. The

  The treatment conditions for the fluorine treatment are set so that a sufficient amount of fluorine is efficiently introduced into the separator and the separator is not deteriorated or burned. For example, the treatment temperature is preferably −50 ° C. or higher, more preferably 0 ° C. or higher, and even more preferably room temperature or higher. In consideration of the heat resistance limit of the separator, the treatment temperature is preferably 200 ° C. or less, more preferably 100 ° C. or less, further preferably 50 ° C. or less, and most preferably 30 ° C. or less. The treatment time is preferably 1 second or longer, more preferably several seconds or longer, further preferably 10 seconds or longer, and most preferably 10 seconds or longer. The treatment time is preferably 10 days or less, more preferably 10 hours or less, further preferably 5 hours or less, particularly preferably 1 hour or less, and most preferably 30 minutes or less. Practical treatment time is preferably in the range of 1 to 4 hours at the longest, and is preferably 1 day or less even when the treatment is performed for a long time. Moreover, it is preferable that atmospheric pressure is near normal pressure. The atmospheric pressure may be lower or higher than normal pressure. Even in this case, the atmospheric pressure is preferably in the range of several hPa to 0.2 MPa.

  The separator after the fluorine treatment may be left in the air as it is, or may be washed with water and then dried.

  Such a fluorine treatment improves the hydrophilicity of the separator surface. This is probably because fluorine is bonded to the surface of the separator by the fluorine treatment, and further, this reacts with water, so that -COOH groups are distributed on the surface of the separator. Further, when the equivalent ratio of the epoxy resin to the phenolic compound in the molding material is in the range of 0.8 to 1.2, the hydrophilicity of the surface of the separator is particularly increased by the fluorine treatment.

  The separator may be subjected to plasma treatment and subsequently subjected to fluorine treatment. In this case, first, contaminants are removed from the surface of the separator by plasma treatment, so that the surface of the separator becomes highly active. In addition, functional groups such as hydroxyl groups are introduced to the surface of the separator by this plasma treatment. Subsequently, when the separator is subjected to fluorine treatment, the fluorine gas is more likely to react on the surface of the separator. For this reason, the hydrophilicity of the surface of the separator is maintained for a longer period. The plasma treatment performed before the fluorine treatment is performed under conditions appropriately set so that a desired functional group can be introduced on the surface of the separator. For example, a model number “PDC210” manufactured by Yamato Material Co., Ltd. is used. Oxygen is used as the plasma generation gas, and the applied power is 150 to 500 W and the treatment time is 30 seconds to 10 minutes.

In the flame treatment, a combustible gas containing a modifier compound is sprayed on the surface of the separator while being burned. By this flame treatment, fine silicon oxide particles adhere to the surface of the separator, and thus excellent hydrophilicity is imparted to the surface of the separator. In particular, when hydroxyl groups are distributed on the surface of the separator, the silicon oxide particles are firmly bonded to the separator by the hydroxyl groups. For this reason, it becomes difficult to drop off the silicon oxide particles from the separator, so that the hydrophilicity of the surface of the separator is maintained high over a long period of time. Further, when the equivalent ratio of the epoxy resin to the phenolic compound in the molding material is in the range of 0.8 to 1.2, the hydrophilicity of the separator surface is particularly increased by the flame treatment. Is burned with a burner or the like, and the separator is moved while spraying the combustible gas toward the separator in a curtain shape. In this case, a flame treatment is uniformly and efficiently applied to the surface of the separator.

  The modifier compound used for the flame treatment contains a silicon compound or an aluminum compound. The silicon compound and the aluminum compound are not particularly limited as long as they can be combusted in a flame of a general gas burner. In consideration of easy availability and ease of handling, the silicon compound is preferably at least one compound selected from the group consisting of alkylsilane compounds, alkoxysilane compounds, siloxane compounds, and silazane compounds. The aluminum compound is preferably at least one compound selected from alkyl aluminum compounds and alkoxy aluminum compounds. Examples of alkylsilane compounds include methylsilane, dimethylsilane, trimethylsilane, tetramethylsilane, tetraethylsilane, dimethyldichlorosilane, dimethyldiphenylsilane, diethyldichlorosilane, diethyldiphenylsilane, methyltrichlorosilane, methyltriphenylsilane, dimethyldiethylsilane, etc. Having a substituent such as octamethyltrisilane, a monosilane compound that may have a substituent, such as a disilane compound that may have a substituent such as hexamethyldisilane, hexaethyldisilane, and chloroheptamethyldisilane Examples thereof may include a trisilane compound. Examples of alkoxysilane compounds include methoxysilane, dimethoxysilane, trimethoxysilane, tetramethoxysilane, ethoxysilane, diethoxysilane, triethoxysilane, tetraethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltrisilane. Ethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dichlorodimethoxysilane, dichlorodiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, trichloromethoxysilane, trichloroethoxysilane, triphenyl Examples include methoxysilane and triphenylethoxysilane. Examples of siloxane compounds include tetramethyldisiloxane, pentamethyldisiloxane, hexamethyldisiloxane, octamethyltrisiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane. Can be mentioned. Examples of the silazane compound include hexamethyldisilazane. Examples of the alkylaluminum compound include trimethylaluminum, triethylaluminum, and tripropylaluminum. Examples of the alkoxyaluminum compound include aluminum methoxide and aluminum ethoxide. These modifier compounds may be used individually by 1 type, or multiple types may be used together. As a specific example of the modifier compound, itro treatment agent manufactured by Itro Co., Ltd. containing a silicon compound can be mentioned.

The ratio of the modifier compound in the combustible gas is not particularly limited, but is preferably in the range of 1 × 10 ⁻¹⁰ to 10 mol%. Moreover, it is preferable that combustible gas contains air. This air can control the temperature of the flame 5 and this air can exert a carrier effect, and the uniformity of the surface treatment is increased. It is also preferred that the combustible gas contains a hydrocarbon gas as a combustion fuel. The hydrocarbon gas preferably contains at least one of propane gas and LPG (liquefied petroleum gas). In this case, propane gas and LPG are inexpensive, and can be burned at a predetermined temperature to stably thermally decompose the modifier compound, thereby further improving the uniformity of the surface treatment. Examples of LPG include butane (normal butane, isobutane), mixed gas of butane / propane, ethane, pentane (normal pentane, isopentane, cyclopentane) and the like.

The combustion temperature of the combustion gas at the time of the flame treatment is set as appropriate, but is set in the range of 500 to 1500 ° C., for example. The blowing time of the combustible gas to the separator is also set as appropriate. For example, it is set in the range of 0.1 to 100 seconds per 100 cm ^{2 of the} separator area.

  The separator may be subjected to plasma treatment and subsequently subjected to flame treatment. In this case, first, contaminants are removed from the surface of the separator by plasma treatment, so that the surface of the separator becomes highly active. In addition, functional groups such as hydroxyl groups are introduced to the surface of the separator by this plasma treatment. Following this, when the separator is subjected to a flame treatment, particles of silicon oxide or aluminum oxide are easily firmly fixed to the surface of the separator via the functional group. For this reason, the hydrophilicity of the surface of the separator is maintained for a longer period. The plasma treatment performed before the flame treatment is performed under conditions appropriately set so that a desired functional group can be introduced on the surface of the separator. For example, a model number “PDC210” manufactured by Yamato Material Co., Ltd. is used. Oxygen is used as the plasma generation gas, and the applied power is 150 to 500 W and the treatment time is 30 seconds to 10 minutes.

  In the ozone water treatment, ozone water is brought into contact with the separator. Thereby, the hydrophilic property of the surface of a separator improves. This is considered to be because functional groups such as carboxyl groups and hydroxyl groups are generated by oxidizing the surface of the separator with ozone. The concentration of ozone water is preferably greater than 50 ppm, more preferably 80 ppm or more. Moreover, it is preferable that the density | concentration of this ozone water is 110 ppm or less.

In the ozone water treatment, an appropriate technique such as immersing the separator in ozone water is adopted. The treatment conditions are appropriately set, but the temperature of the ozone water is preferably normal temperature or lower, and particularly preferably in the range of 0 to 4 ° C. Further, the contact time (treatment time) between the separator and the ozone water is preferably 10 hours or more. The separator with a gasket for a fuel cell is manufactured as described above.

  In the manufacturing process of the separator with a gasket for a fuel cell, after the gasket is laminated on the separator, the separator and the gasket are sequentially subjected to blasting and hydrophilization. For this reason, as described above, even when a component derived from the material for forming the gasket adheres to the separator when the gasket is laminated on the separator, the component is removed from the separator by the blasting process. The amount of impurities deposited on the surface of the film is very low. For this reason, the low surface resistance of a separator is maintained and hydrophilicity becomes high as above-mentioned.

  Further, as a result of increasing the hydrophilicity of the separator as described above, the static contact angle with water on the surface of the separator in the separator with a gasket for a fuel cell is preferably 40 ° or less. In this case, since the hydrophilicity of the separator surface is high, the gas supply / discharge groove 2 in the separator is not easily blocked by water droplets. For this reason, the power generation efficiency of the fuel cell including the separator with the gasket for fuel cell according to the present embodiment is unlikely to decrease. The static contact angle with water is more preferably in the range of 0 ° to 40 °, and further preferably in the range of 0 ° to 30 °. The static contact angle with water on the surface of the separator is adjusted by appropriately setting the conditions for the hydrophilic treatment.

Further, the contact resistance of the separator is preferably 15 mΩcm ² or less. In this case, the separator function of transmitting the electric energy generated by the fuel cell to the outside is exhibited at a high level. The contact resistance of the separator is also adjusted by appropriately setting the conditions for the hydrophilic treatment.

  Further, the metal component may be sucked and removed from the separator with the fuel cell gasket by a magnet. In this case, for example, the separator with the fuel cell gasket is disposed between the pair of magnets, whereby the metal component is sucked and removed from the separator and the gasket. Note that the metal component may be removed from the separator and the gasket by an appropriate method other than suction removal using a magnet. However, the method of washing with a strongly acidic solution is not preferable because the resin constituting the separator and the gasket may be dissolved, and the ultrasonic cleaning may cause the graphite particles to be detached from the separator.

  In addition, the degree of adhesion of the metal component in the separator is determined by observing the surface of the separator after washing the separator with warm water at 90 ° C. for 1 hour and further heating and drying at 90 ° C. for 1 hour. It is confirmed. When a metal component adheres to the separator, a metal oxide (rust) is generated on the surface of the separator by the treatment. Even if the surface of the separator 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 separator after the treatment, and it is more preferable if no metal oxide larger than 50 μm in diameter exists. Further, it is particularly preferable if there is no metal oxide having a diameter larger than 30 μm.

Moreover, it is preferable that the total amount of Fe, Co, and Ni exposed on the surface of the separator is 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 separator 20 is 0.01 μg / cm ² or less.

  Thus, if a metal component is removed from a raw material component, a molding material, or a separator at the time of manufacture of a separator, content of the metal component in a separator will decrease. For this reason, even if the separator is washed with water and then incorporated into the fuel cell, metal oxide (rust) hardly appears on the surface of the separator. For this reason, the desorption of metal ions from the separator in the fuel cell is suppressed, the decrease in proton conductivity of the electrolyte and the decomposition of the electrolyte due to the desorption of such metal ions are suppressed, and the performance of the fuel cell is prolonged. Maintained for a long time.

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

[Examples 1 to 15]
For each example, the raw material components shown in the table below were placed in a stirring mixer ("5XDMV-rr type" manufactured by Dalton) so as to have the composition shown in the table below and mixed with stirring. A molding material was obtained by pulverizing the mixture thus obtained to a particle size of 500 μm or less with a granulator.

  Using this molding material, a separator was formed as follows. First, after 5 seconds have elapsed since the molding material was placed in the mold in the vacuum chamber, pressure reduction in the vacuum chamber was started, and the vacuum chamber was allowed to reach a vacuum degree of 97 kPa over 10 seconds. Subsequently, the molding material was compression molded by lowering the upper mold toward the lower mold and clamping the mold. The compression molding conditions were a mold temperature of 170 ° C., a molding pressure of 35.3 MPa, and a molding time of 3 minutes. Next, the pressure was released while the mold was closed, and after holding for 30 seconds, the mold was opened, and then the separator was taken out from the mold.

  The shape of the obtained separator was a rectangular shape having a plan view of 200 mm × 250 mm, and the thickness was 1.5 mm at the thickest part and 0.5 mm at the thinnest part. Further, by compression molding, 25 grooves having a length of 250 mm, a width of 1 mm, and a depth of 0.5 mm are formed on one surface (first surface) of the separator, and the surface opposite to the first surface ( On the second surface (water channel surface), 25 grooves having a length of 250 mm, a width of 0.5 mm, and a depth of 0.5 mm were formed.

  Subsequently, after applying ethylene-propylene-diene rubber to the outer peripheral portion of the first surface of the separator by a screen printing method, a gasket was formed by heat vulcanization.

  Subsequently, wet blasting was simultaneously performed on the first surface and the second surface of the separator. At this time, the gasket was also wet-blasted. In the wet blast treatment, a wet blast treatment apparatus (model PFE-300T / N) manufactured by Macau Corporation was used, and a slurry containing alumina particles as abrasive grains was used. As the alumina particles, White Morundum (registered trademark) WA series manufactured by Showa Denko KK was used. The average particle size (d50) of the abrasive grains used in this wet blasting is shown in the table below. Further, the three-dimensional surface properties of the first and second surfaces of the separator after the wet blast treatment and the surface of the gasket were measured with a 3D measurement laser microscope, and based on the results, ISO 25178 of the separator and the gasket were measured. -2: The arithmetic average height Sa defined by 2012 was derived. The results are as shown in the table below.

  Subsequently, the separator and the gasket were washed with ion exchange water and further dried with hot air.

  Subsequently, the separators were subjected to plasma treatment in Examples 1 to 10 and 12 to 15 and ozone gas treatment in Example 11.

  In the plasma treatment in Examples 1 to 10 and 12 to 15, the separator was subjected to 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.

  In Example 11, first, oxygen was used as the plasma generating gas, and the surface of the molded body was subjected to plasma treatment under conditions of an applied power of 300 W and a treatment time of 3 minutes. Subsequently, the ozone gas concentration is adjusted by using a combination of an ozone gas generator (for semiconductors) manufactured by Iwatani Corporation and an ozone generator manufactured by Sumitomo Precision Industry Co., Ltd., with a treatment temperature of 25 ° C. and an ozone gas concentration. The surface of the separator was exposed to ozone gas under conditions of 3.5% by volume and a treatment time of 1 hour.

[Comparative Example 1]
The raw material components shown in the following table were mixed in a stirring mixer ("5XDMV-rr type" manufactured by Dalton) so as to have the composition shown in the following table. A molding material was obtained by pulverizing the mixture thus obtained to a particle size of 500 μm or less with a granulator.

  Using this molding material, a separator was formed by the same method and the same conditions as in Example 1.

  Subsequently, a wet blast treatment was performed on the surface of the separator using a slurry containing alumina particles as abrasive grains using a wet blast treatment apparatus (model PFE-300T / N) manufactured by Macau Corporation. As the alumina particles, White Morundum (registered trademark) WA series manufactured by Showa Denko KK was used. The average particle size (d50) of the abrasive grains used in this wet blasting is shown in the table below. In addition, the three-dimensional surface properties of the surfaces of the separator and gasket after wet blasting were measured with a 3D measurement laser microscope, and based on the results, the arithmetic average height of the separator and gasket was defined by ISO 25178-2: 2012. Sa was derived. The results are as shown in the table below.

  Subsequently, the separator was washed with ion-exchanged water and further dried with hot air.

  Subsequently, the separator 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. The processing conditions were the same as the plasma processing in Example 1.

  Subsequently, after applying ethylene-propylene-diene rubber to the outer peripheral portion of the first surface of the separator by a screen printing method, a gasket was formed by heat vulcanization.

  Subsequently, the separator was again subjected to 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.

[Contact resistance evaluation]
In each of the examples and comparative examples, the first surfaces of the separators in the two separators with a gasket for a fuel cell were overlapped with carbon paper interposed therebetween. The separator was sandwiched between two electrodes whose surfaces were plated with gold, and a surface pressure of 1 MPa was applied between the electrodes. In this state, electricity was passed between the two separators from the electrode, and the resistance (average value) was calculated based on the relationship between the voltage between the separators and the current flowing between the separators. The carbon paper used is TGP-HM series (090M: thickness 0.28 mm, 120M: thickness 0.38 mm) manufactured by Toray.

[Static contact angle evaluation]
The separators with gaskets for fuel cells obtained in each Example and Comparative Example were horizontally arranged, and ion exchange water was dropped on the surface of the separator with a dropper, and a measuring instrument manufactured by Kyowa Interface Science Co., Ltd. ) Was used to measure the static contact angle with water.

  Further, this separator with a gasket for a fuel cell was poured into warm water at 90 ° C. and left for a certain period of time, and then dried. The standing time was 500 hours, 1000 hours, 1500 hours, and 2000 hours. About the separator in the separator with a gasket for fuel cells after this treatment, the static contact angle with water was measured in the same manner as described above.

[Bending strength evaluation]
In each of the examples and comparative examples, a molded product for measuring bending strength having a size of 80 mm × 10 mm × 4 mm was prepared in the same manner as in the case of manufacturing a separator. The bending strength was measured under the condition of 2 mm / min.

[TOC evaluation]
In accordance with JIS K0551-4.3, first, the separators with gaskets for fuel cells of each Example and Comparative Example were washed with methanol for 1 minute and then washed with ion-exchanged water for 1 minute. Next, a separator with a fuel cell gasket and ion-exchanged water were placed in a glass container so that the amount of ion-exchanged water was 100 ml with respect to 10 g of the separator, and treated at 90 ° C. for 50 hours. After adjusting the pH to 2 or less by adding phosphoric acid to the ion-exchanged water after the treatment, the amount of organic carbonic acid is measured using a wet oxidation-infrared TOC measurement method (using “Toray Stro TOC Automatic Analyzer MODEL 1800” manufactured by Toray Engineering Co., Ltd.). Was measured.

[Water-soluble ion analysis]
The separator with gasket for fuel cell in each Example and Comparative Example was washed with methanol for 1 minute, and then washed with ion-exchanged water for 1 minute. Next, a separator with fuel cell gasket and ion-exchanged water were placed in a polyethylene container so that the amount of ion-exchanged water was 100 ml with respect to 10 g of the mass of the separator, and treated at 90 ° C. for 50 hours. The ion-exchanged water (extracted water) after the treatment was measured by ion chromatography (“CDD-6A” manufactured by Shimadzu Corporation).

[Electrical conductivity evaluation]
The separator with gasket for fuel cell in each Example and Comparative Example was washed with methanol for 1 minute, and then washed with ion-exchanged water for 1 minute. Next, a separator with fuel cell gasket and ion-exchanged water were placed in a polyethylene container so that the amount of ion-exchanged water was 100 ml with respect to 10 g of the mass of the separator, and treated at 90 ° C. for 50 hours. The ion-exchanged water (extracted water) after the treatment was measured with a conductivity meter.

The details of the components in the table are as follows. In addition, the mixture ratio in a table | surface is a ratio which converted all the components into solid content.
Epoxy resin A: Cresol novolac type epoxy resin (“EOCN-1020-75” manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 199, melting point 75 ° C.)
Epoxy resin B: Bisphenol F type epoxy resin (DIC Corporation “830CRP”, epoxy equivalent 171, liquid at 25 ° C.)
Curing agent A: Novolac type phenolic resin (“PSM6200” manufactured by Gunei Chemical Industry Co., Ltd., OH equivalent 105)
Thermosetting phenolic resin A: Resol type phenolic resin (Gunei Chemical Co., Ltd. “Sample A”, melting point 75 ° C., ortho-ortho bond ratio 25-35% by 13C-NMR analysis, ortho-para bond ratio 60 -70%, para-para bond ratio 5-10%)
・ 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 Nihon Unicar Co., Ltd.)
Wax A: natural carnauba wax ("H1-100" manufactured by Dainichi Chemical Co., Ltd., melting point 83 ° C)
Wax B: Montanic acid bisamide (“J-900” manufactured by Dainichi Chemical Industry Co., Ltd., melting point: 123 ° C.)

12 Gasket 20 Separator 30 Separator with gasket for fuel cell

Claims (7)

Preparing a molding material containing graphite particles and a thermosetting resin component, wherein the ratio of the graphite particles is in the range of 70 to 90% by mass with respect to the total solid content;
By molding the molding material, the molding material has a first surface in the thickness direction and a second surface opposite to the first surface, and a fuel gas or an oxidant is formed on the first surface. Producing a separator having a groove for flowing gas ;
Laminating a gasket to the separator;
By performing a blasting process on the separator and the gasket, the arithmetic average height Sa defined by ISO 25178-2: 2012 of the first surface is in the range of 0.8 to 1.2 μm. After the step of adjusting the arithmetic average height Sa defined in ISO 25178-2: 2012 on the second surface to a range of 0.5 to 0.7 μm, respectively , and after the blast treatment, The manufacturing method of the separator with a gasket for fuel cells including the step which performs the hydrophilic treatment which improves the hydrophilic property of the surface. 2. With the gasket for a fuel cell according to claim 1, the arithmetic average height Sa defined by ISO 25178-2: 2012 is adjusted to a range of 0.3 to 0.6 μm on the surface of the gasket by the blast treatment. Separator manufacturing method. The manufacturing method of the separator with a fuel cell gasket according to claim 1 or 2 , wherein a static contact angle with water on the surface of the separator is adjusted to 40 ° or less by the hydrophilization treatment. The fuel cell according to any one of claims 1 to 3 , wherein the hydrophilization treatment includes at least one of a plasma treatment in which the separator is exposed to plasma and an ozone gas treatment in which the separator is exposed to ozone gas. Manufacturing method of separator with gasket. The arithmetic average height Sa defined by ISO 25178-2: 2012 of the first surface and the second surface of the separator after blasting is measured, and based on the measurement result, The arithmetic average height Sa defined by ISO 25178-2: 2012 is within the range of the arithmetic average height Sa defined by ISO 25178-2: 2012 of 0.8 to 1.2 μm. The manufacturing method of the separator with a gasket for fuel cells as described in any one of Claims 1 thru | or 4 which sets the conditions of a blast process so that it may become the range of 0.5-0.7 micrometer. A separator containing a cured product of a thermosetting resin component and graphite particles, and a ratio of the graphite particles in the range of 70 to 90% by mass, and a gasket laminated on the separator,
The static contact angle with water on the surface of the separator is 40 ° or less,
The separator has a first surface in the thickness direction and a second surface opposite to the first surface, and causes the fuel gas or the oxidant gas to flow through the first surface. Groove is formed,
The arithmetic average height Sa defined by ISO 25178-2: 2012 of the first surface is in a range of 0.8 to 1.2 μm,
A separator with a gasket for a fuel cell , wherein the arithmetic average height Sa defined by ISO 25178-2: 2012 on the second surface is in the range of 0.5 to 0.7 μm . The separator with a gasket for a fuel cell according to claim 6, wherein an arithmetic average height Sa defined by ISO 25178-2: 2012 on the surface of the gasket is in a range of 0.3 to 0.6 μm.