JP2006012712A - Manufacturing method of separator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a separator capable of improving productivity and of attaining a high yield. <P>SOLUTION: Conductive slurry is applied to a surface of a metal plate in an application process, and the applied conductive slurry is dried to form an application layer in an application layer formation process. A molding layer with a passage formed is formed by a stamper in a molding process; and the molding layer is hardened to form a resin layer with a gas passage formed in a molding layer hardening process. In a sealing part formation process, a sealing part is formed in the periphery by pressing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a separator provided in a stack type polymer electrolyte fuel cell.

  Conventionally, the necessity of energy saving for effective use of limited energy resources and prevention of global warming has been widely recognized. Today, thermal power supplies energy demand in the form of converting thermal energy into electric energy.

  However, coal and oil necessary for thermal power generation are resources with limited reserves, and new energy resources to replace them are required. Therefore, attention is being focused on fuel cells that generate chemical power using hydrogen as a fuel.

  The fuel cell has two electrodes and an electrolyte sandwiched between the electrodes. At the cathode, the supplied hydrogen is ionized to form hydrogen ions that move through the electrolyte toward the anode. At the anode, the supplied oxygen reacts with hydrogen ions that have moved through the electrolyte to generate water. Electrons generated when hydrogen is ionized move from the cathode through the wiring to the anode, whereby a current flows and electricity is generated.

  Fuel cells are classified into four types mainly based on the difference in electrolyte. Solid electrolyte fuel cell (SOFC) using ion conductive ceramics as electrolyte, solid polymer fuel cell (PEFC) using hydrogen ion conductive polymer membrane as electrolyte, phosphorus using high concentration phosphoric acid as electrolyte There are four types: an acid fuel cell (PAFC) and a molten carbonate fuel cell (MCFC) using an alkali metal carbonate as an electrolyte. Among them, development of a polymer electrolyte fuel cell (PEFC) having an operating temperature as low as 80 ° C. is in progress.

  The structure of the polymer electrolyte fuel cell includes an electrolyte layer provided with a catalyst electrode on the surface, a separator provided with a groove for supplying hydrogen and oxygen, sandwiching the electrolyte layer from both sides, and collecting electricity generated by the electrode It includes a current collector plate. As with the electrolyte layer, improvements have been made to the separator.

As the required characteristics of the separator, it is necessary to have high conductivity, high airtightness with respect to the fuel gas and the oxidant gas, and high corrosion resistance against the reaction when oxidizing and reducing hydrogen and oxygen.
In order to satisfy these requirements, the following separator materials are used.

  The most commonly used is dense carbon. Dense carbon is excellent in electrical conductivity and corrosion resistance, and has high mechanical strength. In addition, it has good workability and is lightweight. However, it is vulnerable to vibrations and shocks and requires cutting, which increases the processing cost. Moreover, it is necessary to perform a gas impermeability treatment.

  Synthetic resins are also used, and thermosetting resins such as phenol resins and epoxy resins are used. Synthetic resins are mainly characterized by low cost, but have poor dimensional stability and poor conductivity.

  From the viewpoints of conductivity, workability, sealing properties, etc., metals are often used. As the metal, titanium and stainless steel are mainly used. However, metal is easily corroded, and metal ions are taken into the electrolyte membrane and ion conductivity is lowered. Therefore, it is necessary to perform gold plating on the separator surface.

  Rubber is also used, and ethylene-propylene-diene rubber is used. Rubber has low gas permeability and high sealing properties.

  Patent Document 1 discloses a solid polymer electrolyte fuel cell. In this solid polymer electrolyte fuel cell, a metal thin plate on which a passive film is easily formed by the atmosphere, such as stainless steel and titanium alloy, is used as a separator, and the separator is processed into a predetermined shape by pressing.

  Patent Document 2 discloses a fuel cell separator. The separator for a fuel cell includes a first resin layer having a volume resistivity of 1.0 Ω · cm or less and a volume resistivity of a first resin layer mixed on at least one surface of a metal substrate with a resin and a conductive filler. A smaller second resin layer is provided to improve current collecting performance, moldability, strength, and corrosion resistance.

  As described above, in the fuel cell separator described in Patent Document 2, as in the solid polymer electrolyte fuel cell separator described in Patent Document 1, gas flow paths are formed by pressing.

  In addition to press working, the separator of the polymer electrolyte fuel cell described in Patent Document 3 forms a gas flow path by printing a conductive material on a conductive substrate. Specifically, a plate-like molded body mainly composed of carbon powder and a thermosetting resin is used as the conductive base material, and a carbon paste containing carbon powder as the main component is used as the conductive material.

JP-A-8-180883 JP 2003-297383 A JP 2001-767748 A

  Future separators are required to be thinner and lighter, and in order to achieve this, it is necessary to reduce the thickness and weight of the metal substrate and make the gas flow path finer. However, like the separators described in Patent Document 1 and Patent Document 2 If the gas flow path is formed by press working, warpage and distortion are large, and the dimensional accuracy is deteriorated, and the yield is lowered due to the deterioration of the dimensional accuracy.

  The separator described in Patent Document 3 can cope with the miniaturization of the gas flow path by printing a carbon paste. However, since the base material is a thermosetting resin, the dimensional stability of the base material itself is low. The problem of being bad remains.

  Furthermore, the conventional separator including the separators described in Patent Documents 1 to 3 needs to include a gasket between the separator and the electrolyte layer in order to prevent fluid leakage.

  An object of the present invention is to provide a separator manufacturing method that improves productivity and achieves a high yield.

The present invention provides a separator having a separation portion that is interposed between a plurality of electrolyte assemblies provided with catalyst electrodes on the surface in the thickness direction of an electrolyte layer containing an electrolyte medium and separates a flow path of a fuel gas and an oxidant gas. A method,
An application step of applying conductive slurry to the surface of the metal plate;
A coating layer forming step of forming a coating layer by removing the solvent contained in the coated conductive slurry;
A molding step of forming a molding layer with a flow path in the coating layer by a stamper;
And a molded layer curing step of curing the molded layer to form a resin layer.

  In the present invention, the conductive slurry includes a binder made of a curable monomer, a curable oligomer, or a curable prepolymer for forming a rubber or a synthetic resin, a conductive filler made of a metal compound or a carbon-based material, and a solvent. It is obtained by mixing and.

  In the present invention, the application step is characterized in that the conductive slurry is applied by a dipping method, a doctor blade method, or a curtain coating method.

  Moreover, this invention is characterized by removing a solvent by spraying a hot air on the apply | coated conductive slurry, and drying it at an application layer formation process.

  Moreover, this invention is characterized by including the board | substrate process process which performs the process for increasing the adhesiveness with a coating layer on the metal plate surface before a coating process.

  In the substrate processing step, the present invention is characterized in that triazine thiol or polyaniline is diffused on the surface of the metal plate.

The present invention also provides a separator having a separation portion that is interposed between a plurality of electrolyte assemblies provided with catalyst electrodes on the surface in the thickness direction of an electrolyte layer containing an electrolyte medium and that separates fuel gas and oxidant gas flow paths. A manufacturing method comprising:
A coating layer forming step of forming a coating layer made of conductive rubber or synthetic resin on the entire surface of the flat metal plate;
An application step of applying a conductive slurry to the surface of the coating layer;
A coating layer forming step of forming a coating layer by removing the solvent contained in the coated conductive slurry;
A molding step of forming a molding layer with a flow path in the coating layer by a stamper;
And a molded layer curing step of curing the molded layer to form a resin layer.

  Moreover, this invention has the high conductive layer formation process which forms the highly conductive layer which has the electroconductivity higher than the electroconductivity of a resin layer on the resin layer surface.

  Further, the present invention is characterized in that in the highly conductive layer forming step, the highly conductive layer is formed at least in a region where the resin layer is in contact with the electrolyte assembly.

In the present invention, the separator has a seal portion that is provided on the outer peripheral portion and prevents leakage of fuel gas and oxidant gas,
A region corresponding to the seal portion is a seal protrusion that extends in parallel with the electrolyte layer exposed from the electrolyte assembly by pressing, and the top portion thereof is configured to be pressed against the electrolyte layer by a spring force. A seal protrusion is formed.

  According to the present invention, there is provided a method for producing a separator interposed between a plurality of electrolyte assemblies in which a catalyst electrode is provided on the surface in the thickness direction of an electrolyte layer containing an electrolyte medium. The separator includes a separation unit that separates the flow paths of the fuel gas and the oxidant gas.

  First, an electroconductive slurry is apply | coated to the metal plate surface at an application | coating process, the solvent contained in the electroconductive slurry apply | coated at the application layer formation process is removed, and an application layer is formed. In the molding step, a molding layer having a flow path in the coating layer is formed by a stamper, and in the molding layer curing step, the molding layer is cured to form a resin layer.

  By forming the resin layer provided with the flow path by stamper molding, the dimensional accuracy is higher than that of the conventional press working, and warpage and distortion do not occur. Therefore, the productivity of the separator can be improved and a high yield can be realized. Furthermore, the degree of freedom in designing the flow path pattern to be formed is greatly improved. For example, in the case of press working, the pattern design is limited because the pattern is formed integrally with the front and back and the linear pattern increases, but stamper molding can form completely different patterns on each surface of the separator. It is also possible to form curved and hole-shaped patterns.

  According to the invention, the conductive slurry includes a binder made of a curable monomer, a curable oligomer, or a curable prepolymer for forming a rubber or a synthetic resin, and a conductive filler made of a metal compound or a carbon-based material. It can be easily realized by mixing with a solvent.

  According to the invention, in the coating step, the conductive slurry is applied by a dipping method, a doctor blade method, or a curtain coating method.

According to the invention, in the coating layer forming step, the solvent is removed by blowing hot air to the coated conductive slurry and drying it.
Thereby, the characteristics (layer thickness, surface state, etc.) of a desired coating layer can be easily realized.

  Moreover, according to this invention, the process for increasing the adhesiveness with a coating layer is performed to the metal plate surface by a board | substrate process process before a coating process. More specifically, the diffusion layer is formed by coating the surface of the metal plate with a conductive coupling agent typified by triazine thiols, or coating with a conductive polymer typified by polyanilines. . Since triazine thiols and polyanilines diffused on the metal surface exhibit conductivity, it is possible to secure electrical conductivity with the resin layer that is finally formed, to reduce internal resistance, and to generate electric power. Can be taken out as a direct current with a minimum internal loss.

  According to the present invention, there is provided a method for producing a separator interposed between a plurality of electrolyte assemblies in which a catalyst electrode is provided on the surface in the thickness direction of an electrolyte layer containing an electrolyte medium. The separator includes a separation unit that separates the flow paths of the fuel gas and the oxidant gas.

  First, a coating layer made of conductive rubber or synthetic resin is formed on the entire surface of the flat metal plate in the coating layer forming step. An electroconductive slurry is apply | coated to the coating layer surface at an application | coating process, the solvent contained in the electroconductive slurry apply | coated at the application layer formation process is removed, and an application layer is formed. In the molding step, a molding layer having a flow path in the coating layer is formed by a stamper, and in the molding layer curing step, the molding layer is cured to form a resin layer.

  By covering the surface of the metal plate with the coating layer, surface changes such as corrosion caused by hydrogen gas, oxygen gas, and cooling water can be prevented. Further, by forming the resin layer provided with the flow path by stamper molding, the dimensional accuracy is higher than that of the conventional press working, and warpage and distortion do not occur. Therefore, the productivity of the separator can be improved and a high yield can be realized. Furthermore, the degree of freedom in designing the flow path pattern to be formed is greatly improved. For example, in the case of press working, the pattern design is limited because the pattern is formed integrally with the front and back and the linear pattern increases, but stamper molding can form completely different patterns on each surface of the separator. It is also possible to form curved and hole-shaped patterns.

  According to the invention, in the highly conductive layer forming step, a highly conductive layer having conductivity higher than that of the resin layer is formed on the surface of the resin layer. The highly conductive layer is formed at least in a region where the resin layer is in contact with the electrolyte assembly.

  By forming the highly conductive layer on the surface of the resin layer, the contact resistance with the catalyst electrode can be reduced and the power recovery rate can be improved.

  Moreover, according to this invention, the separator is provided in the outer peripheral part, and is provided with the seal part which prevents leakage of fuel gas and oxidant gas.

  A seal protrusion that extends in parallel with the electrolyte layer exposed from the electrolyte assembly in a region corresponding to the seal portion by pressing, and the top of the seal protrusion is pressed against the electrolyte layer by a spring force. Protrusions are formed.

  Since the seal portion is formed by pressing, high sealing performance can be realized with simple processing.

  FIG. 1 is a perspective view schematically showing a state in which a polymer electrolyte fuel cell (abbreviated as PEFC) 100 is developed. The PEFC 100 includes a separator 1, a fuel battery cell 2, a current collector plate 3, an insulating sheet 4, an end flange 5, and an electrode wiring 12. The PEFC 100 is configured in a so-called stack state in which a plurality of fuel cells 2 are connected in series in order to obtain a high voltage and a high output. In order to configure this stack state, a separator is disposed between the fuel cells 2, and hydrogen and oxygen are supplied to each fuel cell 2 and the generated electricity is recovered. Therefore, as shown in FIG. 1, the fuel cells 2 and the separators 1 are alternately arranged. The separator 1 is arranged on the outermost layer of this arrangement, and the current collector plate 3 is provided on the outer side of the separator 1. The current collector plate 3 is provided to collect and take out the electricity collected by each separator 1 and is connected to the electrode wiring 12. The insulating sheet 4 is provided between the current collector plate 3 and the end flange 5, and prevents current from leaking from the current collector plate 3 to the end flange 5. The end flange 5 is a case for holding the plurality of fuel cells 2 in a stacked state.

  A hydrogen gas supply port 6, a cooling water supply port 7, an oxygen gas supply port 8, a hydrogen gas discharge port 9, a cooling water discharge port 10 and an oxygen gas discharge port 11 are formed in the end flange 5. The gas and water fluid supplied from each supply port passes through each forward path penetrating in the stacking direction of the fuel cells 2 and is folded back by the outermost separator 1 and is discharged from each discharge port through each return path.

  The forward path and the return path are branched by each separator 1, and each fluid flowing in the forward path flows into the return path through a flow path formed by the separator 1 and parallel to the surface direction of the fuel cell 2. Since hydrogen gas and oxygen gas are consumed in the fuel battery cell 2, unreacted gas is discharged through the return path. The discharged unreacted gas is recovered and supplied again from the supply port. Since water is generated by the reaction between oxygen and hydrogen in the vicinity of the oxygen gas flow path, the discharged oxygen gas contains water. In order to supply the discharged oxygen gas again, it is necessary to remove water.

  The hydrogen gas that is a fuel gas and the oxygen gas that is an oxidant gas do not need to be hydrogen and oxygen alone, but can be any gas other than hydrogen and oxygen that does not deteriorate or denature the flow path in contact. May be included. For example, air containing nitrogen as oxygen gas may be used. The hydrogen source is not limited to hydrogen gas, and may be methane gas, ethylene gas, natural gas, or ethanol.

  FIG. 2 is a horizontal sectional view of the unit battery 101 including the separator 1. The unit battery 101 is composed of one fuel battery cell 2 and two separators 1 arranged on both sides of the unit battery 101. The unit battery 101 has a minimum configuration capable of generating electric power by supplying hydrogen and oxygen.

A fuel cell 2 as an electrolyte assembly includes a polymer film 20 as an electrolyte medium and a catalyst electrode 21 formed on the surface of the polymer film 20 in the thickness direction. The MEA (Membrane Electrode)
Also called Assembly.

  The polymer membrane 20 is a proton conductive electrolyte membrane that transmits hydrogen ions (protons), and a perfluorosulfonic acid resin membrane (for example, a product name “Nafion” manufactured by DuPont) is often used.

  The catalyst electrode 21 is laminated on the surface of the polymer film 20 in the thickness direction as a carbon layer containing a catalyst metal such as platinum or ruthenium. When hydrogen gas or oxygen gas is supplied to the catalyst electrode 21, an electrochemical reaction occurs at the interface between the catalyst electrode 21 and the polymer film 20 to generate DC power.

  The polymer film 20 has a thickness of about 0.1 mm, and the catalyst electrode 21 is formed with a thickness of several μm although it varies depending on the catalyst metal contained therein.

  The separator 1 has a separation part 13 that separates the flow paths of hydrogen gas and oxygen gas, and a seal part 14 that is provided on the outer periphery and prevents leakage of hydrogen gas and oxygen gas. In the present embodiment, the catalyst electrode 21 is not formed on the entire surface of the polymer film 20, but the polymer film 20 is exposed on the surface over an outer width of 1 to 20 mm, preferably 5 to 10 mm. The separator 13 of the separator 1 is formed in a region facing the region where the catalyst electrode 21 is formed, and the seal portion is formed in a region facing the region where the polymer film 20 is exposed.

  In the separation part 13, a plurality of flow channel grooves parallel to each other and parallel to the surface on which the catalyst electrode 21 is formed are formed on both surfaces in the thickness direction. This channel groove has a concave shape in a cross section perpendicular to the gas flow direction. A space surrounded by the separation block 15 and the catalyst electrode 21 provided at a predetermined interval is a hydrogen gas flow path 16 and an oxygen gas flow path 17. The separation block 15 separates the hydrogen gas flow channel 16 and the oxygen gas flow channel 17 so as not to mix hydrogen gas and oxygen gas, and is in contact with the catalyst electrode 21, at the interface between the polymer film 20 and the catalyst electrode 21. The generated DC power is extracted as a DC current. The extracted direct current is collected on the current collector plate 3 through another separation block 15 or the like.

  The channel grooves adjacent to each other are formed so that the open surfaces are in the same direction, and accordingly, the hydrogen gas channel 16 is set on one side and the oxygen gas channel is set on the other side. 17 is set. That is, the gas flow path is set so that the same gas contacts the same catalyst electrode 21. Further, as shown in FIG. 2, the two separators 1 constituting one unit battery 101 are arranged so that the open portions of the flow channel grooves face each other with the fuel battery cell 2 interposed therebetween. That is, the two separators 1 are arranged so as to have a plane-symmetrical relationship with the center of the fuel cell 2 as the symmetry plane. However, the setting of the gas flow path is not a plane-symmetrical relationship, and the flow path grooves facing each other with the fuel cell 2 interposed therebetween are set so as to form gas flow paths for different gases. For example, as shown in FIG. 2, one of the gas flow paths facing each other across the fuel cell 2 is a hydrogen gas flow path 16, and the other is an oxygen gas flow path 17.

  Electric power can be generated by arranging the separator 1 and setting the gas flow path as described above.

  The flow path formed by the flow path groove and the catalyst electrode 21 is not limited to hydrogen gas and oxygen gas, and cooling water may flow. When flowing the cooling water, it is preferable to flow in any of the channel grooves facing each other with the fuel battery cell 2 interposed therebetween.

  As a core material of the separator 1, a flat metal thin plate is used. For example, metal thin plates such as iron, aluminum and titanium, particularly stainless steel (for example, SUS304) steel plates, SPCC (general cold rolled steel plates), and corrosion resistant steel plates are preferred. As for the stainless steel plate, a surface-treated one can be used. For example, a surface pickled, electrolytically etched, containing conductive inclusions, formed with a BA film, or coated with a conductive compound by ion plating can be used. Further, a highly corrosion-resistant stainless steel plate with an ultrafine crystal structure can be used.

  The seal portion 14 is formed with a seal protrusion that extends in parallel with the polymer film 20. The seal projection has an inverted U-shaped or inverted V-shaped cross section perpendicular to the gas flow direction. By making the core material of the separator 1 a metal thin plate, the top portion 18 of the seal projection is pressed against the exposed polymer film 20 by a spring force. Sealing at this pressure contact position can prevent leakage of hydrogen gas and oxygen gas. Further, by forming the seal protrusion in an inverted U shape or an inverted V shape, the membrane contact area of the top portion 18 is reduced, and a high-pressure seal similar to that of an O-ring is realized.

  FIG. 3 is an enlarged view of a main part of the separation unit 13 of the separator 1 according to the first embodiment. Resin layers 32 are formed on both surfaces of a thin metal plate 30 as a core material via an adhesive layer 31, and grooves parallel to each other are provided in the resin layer 32 of the separation portion 13. The grooves provided in the resin layer 32 become the hydrogen gas channel 16 and the oxygen gas channel 17. For the resin layer 32, rubber (elastomer) or synthetic resin can be used.

  In the separation unit 13, the resin layer 32 comes into contact with the catalyst electrode 21, and the DC power generated at the interface between the polymer film 20 and the catalyst electrode 21 is taken out as a DC current and collected through the metal thin plate 30 to the current collector plate. Is done.

  The adhesive layer 31 is coated on the surface of the metal thin plate 30 by coating with a conductive coupling agent typified by triazine thiols or a coating treated with a conductive polymer typified by polyanilines. It is formed as a diffusion layer. Since the triazine thiols and polyanilines diffused on the metal surface exhibit conductivity, the conductivity with the resin layer 32 can be secured and the generated DC power can be taken out as a DC current.

In the present invention, instead of the conventional press working, a conductive slurry is applied to the surface of a thin metal plate and dried to form a coating layer, and then a resin is provided with flow channel grooves by forming irregularities on the coating layer with a stamper. Layer 32 is formed. Since the resin layer 32 needs to have conductivity, a rubber or a synthetic resin containing a conductive filler can be used. In particular, the rubber is preferably polyisobutylene, and the synthetic resin is an epoxy resin, An acrylic resin or the like is preferable, and a resin having an interpenetrating polymer network (abbreviated as “IPN”) structure in which an epoxy resin and an acrylic resin are combined is more preferable. Further, the resin layer 32 needs to be formed as a coating layer once the conductive slurry is dried, and can be flow-path molded by a stamper. First, a binder made of a curable monomer, a curable oligomer or a curable prepolymer and a conductive filler made of a metal compound or a carbon-based material are mixed with a solvent to prepare a conductive slurry, which is applied to the surface of the metal thin plate. After the applied conductive slurry is dried to form a coating layer, the resin layer 32 is formed by molding irregularities on the coating layer with a stamper (mold) provided with a predetermined transfer pattern.

  FIG. 4 is an enlarged view of a main part of the seal portion 14 of the first embodiment. In the seal portion 14, the metal thin plate 30 is in contact with the polymer film 20 and sealed. The seal part 14 is formed by press working.

  In order to press-contact the top 18 of the seal protrusion against the polymer film 20 by a spring force, the position of the top 18 of the seal protrusion in the separator 1 in a state where it does not come into contact with the polymer film 20, that is, before the PEFC 1 is assembled. However, the seal part 14 is formed in advance so that the PEFC 1 is assembled and the polymer film 20 side is further from the position where it is in contact with the polymer film 20. Specifically, as shown in FIG. 5A, when the PEFC 1 is assembled, the position of the top portion 18 of the seal protrusion is determined based on the virtual contact surface A with the catalyst electrode 21. The distance between the contact surface and the top portion 18 is such that the thickness t1 of the catalyst electrode 21 is reached. Therefore, in a state before the PEFC 1 is assembled, as shown in FIG. 5B, the position of the top portion 18 of the seal projection is such that the distance from the contact surface with the catalyst electrode 21 is t2 larger than t1. What is necessary is just to form. Since the connecting portion between the separation portion 13 and the seal projection acts as a spring, the pressure when the top portion 18 is pressed against the polymer film during assembly is determined by this spring force and the contact area. The spring force is obtained by multiplying the spring constant (elastic constant) by the amount of displacement according to Hooke's law. In the separator 1, the spring constant is determined by the material of the separator 1 and the shape of the seal portion 14. The amount of displacement is Δt = t2−t1. Accordingly, the seal pressure can be easily adjusted by changing t2 during processing in a state where the material and shape are determined in advance and the spring constant is determined. Needless to say, the material and shape may be changed in order to achieve the optimum sealing pressure.

  As described above, since the two separators 1 sandwiching the fuel cell 2 are arranged so as to have a plane symmetry, the pressure contact position by the top portion 18 of the seal projection also has a plane of symmetry about the center of the fuel cell 2. As shown in FIG. The sealing performance is improved by the pressure contact position of the top 18 being opposed.

FIG. 6 is a production process diagram illustrating a method for producing a separator according to an embodiment of the present invention.
This manufacturing process includes a substrate processing process, a slurry preparation process, a coating process, a coating layer forming process, a molding process, a molding layer curing process, and a seal portion forming process.

  In order to realize the separation block shape as shown in FIG. 2 by molding using a stamper, it is necessary to form a thick film in which the thickness of the molded resin layer is about 100 μm to 500 μm. Further, since the resin layer 32 has conductivity, it is necessary to contain a large amount of conductive filler.

  Due to the necessity of a thick film, a conductive slurry having a certain degree of viscosity must be used. Therefore, the composition of the conductive slurry is important in order to achieve the required electrical and structural properties.

  In the substrate processing step of step S1, when using a metal thin plate 30 such as a stainless steel plate as a substrate, the passive film is removed by etching or the like on the surface of the metal thin plate 30 in order to ensure conductivity with the resin layer 32. Then, the adhesive layer 31 is formed. Specifically, in order to obtain a predetermined outer shape and gas path in the thickness direction, a die cutting process is performed, and the surface of the metal sheet subjected to the die cutting process is subjected to a conductive coupling agent typified by triazine thiols. Coating is performed by doping with a conductive polymer represented by polyanilines.

  In the slurry preparation step of step S2, a conductive slurry used in a subsequent application step is prepared.

  In order to realize low-cost production, it is desirable that not only raw materials but also processing steps are rich in mass productivity. In the present invention, since a large amount of conductive filler is used, it is difficult to form a layer on the surface of the metal thin plate because it has high viscosity and high consistency only by mixing a binder, a conductive filler and an additive. Therefore, by mixing a binder, a conductive filler, an additive, and the like with a solvent, the viscosity can be lowered and it can be easily applied to the surface of the thin metal plate. Furthermore, by using a solvent, it is possible to use a higher molecular weight binder, and the characteristics of the resin layer 32 can be improved. Accordingly, the conductive slurry is preferably prepared by mixing a liquid and reactive binder, a large amount of conductive filler, a polymerization catalyst for promoting curing, and other additives in a solvent.

The conductive slurry to be prepared is classified into two types depending on the solvent used. One is an organic solvent type slurry using an organic solvent as a solvent, and the other is an aqueous type slurry using water as a solvent. Furthermore, the organic solvent type slurry and the aqueous type slurry are classified into two types, respectively. The organic solvent type slurry is classified into a dissolved solvent type slurry and a non-aqueous dispersion type (NAD type) slurry, and the aqueous type slurry is classified into an emulsion type slurry and a water soluble type slurry.
Below, each kind of slurry is demonstrated.

・ Solvent solvent type slurry Solvent solvent type slurry is an organic solvent such as aromatic solvent such as benzene, toluene and xylene, ketone solvent such as acetone, ester solvent such as ethyl acetate and butyl ester. Among them, one type or a mixture of two or more types can be used. A conductive slurry is prepared by mixing a binder, a conductive filler, a polymerization catalyst, an additive, and an organic solvent.

-Non-aqueous dispersion type slurry A non-aqueous dispersion type slurry disperses a binder etc. using mineral terpene (aliphatic hydrocarbon solvent) instead of the above-mentioned dissolution solvent. Compared with the case of using a dissolving solvent, a conductive slurry having low pollution can be realized.

-Emulsion type slurry Emulsion type slurry is adjusted when a binder that does not dissolve in water is used. An auxiliary agent (emulsifier) such as a surfactant is added to water, and a binder that does not dissolve in water is emulsified and dispersed to realize a stable conductive slurry. Further, methyl alcohol, ethyl alcohol, carbitol or the like may be added as a cosolvent (not necessarily volatile).

-Water-soluble slurry The water-soluble slurry is adjusted when a modified binder that dissolves in water is used. A conductive slurry is realized by dissolving a modified binder or the like in water. Further, ethylene glycol n-butyl ether, propylene glycol propyl ether, ethylene glycol t-butyl ether or the like is added as a cosolvent.

  In the actual manufacturing process, the type of slurry to be adjusted may be selected depending on the type of binder, conductive filler, and polymerization catalyst used.

  As the binder, since the resin layer 32 is made of rubber or synthetic resin, a curable monomer, curable oligomer, or curable prepolymer for realizing these may be used. In particular, in the subsequent molding layer curing step, curing is performed by combining photocuring and thermal curing, and therefore it is preferable to use a photocurable monomer, a photocurable oligomer, or a photocurable prepolymer. For example, acrylic monomers or oligomers, epoxy monomers or oligomers can be used. As the acrylic monomer or oligomer, epoxy acrylate, polyester acrylate, isobornial acrylate and the like are preferable.

  As the conductive filler, a metal compound or a carbon-based material can be used. As the metal compound, strontium carbide, strontium nitride, cesium oxide and the like are preferable. As the carbon-based material, there are a powdery material and a fibrous material. As the powdery material, artificial graphite, natural graphite, carbon black and the like are preferable, and as the fibrous material, carbon fiber, carbon nanotube, carbon nanofiber and the like are preferable.

The photocuring reaction includes an acrylic radical polymerization reaction and an epoxy cationic polymerization reaction. In particular, when an IPN structure resin composed of an epoxy resin and an acrylic resin is used as the resin layer 32, the conductive slurry is used as a conductive slurry. A cationic polymerization initiator and a radical polymerization initiator are added.
As other additives, a viscosity reducing agent or the like can be used.

The substance constituting the conductive slurry will be illustrated more specifically.
Examples of lipophilic acrylic monomers include dicyclopentanyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl tribromo (meth) acrylate, and phenoxyethyl tribromo (meth) acrylate. Biphenylethoxy (meth) acrylate, biphenyl epoxy (meth) acrylate, naphthylethoxy (meth) acrylate, fluorene epoxy (meth) acrylate, bisphenol A di (meth) acrylate, bisphenol A tetrabromodi (meth) acrylate , Ethoxy modified di (meth) acrylate bisphenol A, tetrabromoethoxy modified di (meth) acrylate bisphenol A, di (meth) acrylate bisphenol A epoxy, ethoxy modified di (meth) acrylate bisphenol A epoxy, Tetoraburomoji (meth) acrylate bisphenol A epoxy, such as tetra-bromoethoxy-modified di (meth) acrylate of bisphenol A epoxy and the like.

  Examples of hydrophilic acrylic monomers include 2-hydroxyethyl (meth) acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl acrylate, N, N-dimethylacrylamide, N, N-diethylacrylamide, acryloylmorpholine, N, N-dimethylaminopropylacrylamide, isopropylacrylamide, dimethylaminoethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meta ) Glycerin (meth) such as ethylene glycol-based (meth) acrylate such as acrylate, trimethylolpropane tri (meth) acrylate Chestnut rates esters, (meth) acrylic acid ester of hexanediol di (meth) diols such as acrylate, and Neopenchiruji (meth) acrylate.

  Epoxy resins include aromatic epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins, and polyglycidyl ethers of polyhydric phenols having at least one aromatic nucleus or their alkylene oxide adducts as aromatic epoxy resins. For example, glycidyl ether and epoxy novolac resin produced by the reaction of bisphenol A, bisphenol F or its alkylene oxide adduct and epichlorohydrin can be mentioned. In addition, as the alicyclic epoxy resin, a polyglycidyl ether of a polyhydric alcohol having at least one alicyclic ring, or a cyclohexene or cyclopentene ring-containing compound is mixed with an appropriate oxidizing agent such as hydrogen peroxide or peracid. Examples thereof include cyclohexene oxide or cyclopentene oxide-containing compound obtained by epoxidation.

  Examples of alicyclic epoxy resin monomers include hydrogenated bisphenol A diglycidyl ether, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5, 5-spiro-3,4-epoxy) cyclohexane-meta-dioxane, bis (3,4-epoxycyclohexylmethyl) adipate, vinylcyclohexene dioxide, 4-vinylepoxycyclohexane, bis (3,4-epoxy-6-methyl) Cyclohexyl-3,4-epoxy-6-methylcyclohexane) carboxylate, methylenebis (3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di (3,4-epoxycyclohexylmethyl) Ether, ethylenebis (3,4-epoxycyclohexane carboxylate), epoxy hexahydrophthalic acid dioctyl and epoxy hexahydrophthalic acid di-2-ethylhexyl and the like.

  Examples of aliphatic epoxy resin monomers include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, polyglycidyl esters of aliphatic long-chain polybasic acids, homopolymers and copolymers of glycidyl acrylate and glycidyl methacrylate, and the like. Typical examples are 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycol. One or more alkylene oxides for aliphatic polyhydric alcohols such as glycidyl ether, diglycidyl ether of polypropylene glycol, ethylene glycol, propylene glycol and glycerin Polyglycidyl ethers of polyether polyols obtained by adding include diglycidyl esters of aliphatic long-chain dibasic acids. Furthermore, monoglycidyl ether of higher aliphatic alcohol, phenol, cresol, butylphenol or polyether alcohol monoglycidyl ether obtained by adding alkylene oxide to these, glycidyl ester of higher fatty acid, epoxidized soybean oil, epoxy butyl stearate Octyl epoxy stearate, epoxidized linseed oil, epoxidized polybutadiene sugar and the like.

  Further, examples of the cationic polymerization reactive substance other than the epoxy resin include oxetane compounds such as trimethylene oxide, 3,3-dimethyloxetane, and 3,3-dichloromethyloxetane; tetrahydrofuran, 2,3-dimethyltetrahydrofuran and the like. Oxolane compounds; cyclic acetal compounds such as trioxane, 1,3-dioxolane, 1,3,6-trioxane cyclooctane; cyclic lactone compounds such as β-propiolactone and ε-caprolactone; ethylene sulfide, thioepichloro Thiirane compounds such as hydrin; 1,3-propyne sulfide, thietane compounds such as 3,3-dimethylthietane; ethylene glycol divinyl ether, alkyl vinyl ether, 3,4-dihydropyran-2-methyl (3,3) 4- Dihydropyran-2-carboxylate), vinyl ether compounds such as triethylene glycol divinyl ether; spiro orthoester compounds obtained by reaction of epoxy compounds with lactones; ethylenically unsaturated compounds such as vinylcyclohexane, isobutylene, polybutadiene, and And derivatives of the above compounds.

Examples of cationic polymerization initiators include diazonium salts, iodonium salts, sulfonium salts, selenium salts, pyridinium salts, ferrocenium salts, phosphonium salts, and thiopyrinium salts, but aromatics that are relatively thermally stable. Onium salt polymerization initiators such as iodonium salts and aromatic sulfonium salts are preferred. In order to activate the onium salt polymerization initiator, irradiation with ultraviolet rays and visible light is preferable. When onium salt polymerization initiators such as aromatic iodonium salts and aromatic sulfonium salts are used, the anions include BF ₄ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , PF ₆ ⁻ , B (C ₆ F ₅ ) ₄ ^{− and the} like. Is mentioned.

As a commercial product of a cationic polymerization initiator, for example, Cyracure UVI-6974 (mixture of bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluoroantimonate and diphenyl-4-thiophenoxyphenylsulfonium hexafluoroantimonate) Syracure UVI-6990 (hexafluorophosphate of UVI-6974) (manufactured by Union Carbide), Adekaoptomer SP-151, Adekaoptomer SP-170 (Bis [4- (di (4- (2-hydroxy Ethyl) phenyl) sulfonio) phenyl] sulfide), Adekaoptomer SP-150 (hexafluorophosphate of Adekaoptomer SP-170), Adekaoptomer SP-171 (above, manufactured by Asahi Denka), and DTS-10 , DTS-103, NAT-103, NDS-103 ((4-hydroxynaphthyl) -dimethylsulfonium hexafluoroantimonate), TPS-102 (triphenylsulfonium hexafluorophosphate), TPS-103 (triphenylphosphonium hexafluoroantimony) Nate), MDS-103 (4-methoxyphenyl-diphenylsulfonium hexafluoroantimonate), MPI-103 (4-methoxyphenyliodonium hexafluoroantimonate), BBI-101 (bis (4-t-butylphenyl) iodonium hexa) Fluorophosphate), BBI-103 (bis (4-t-butylphenyl) iodonium hexafluoroantimonate) (hereinafter referred to as Midori Kagaku) and Irgacure 2 1 (eta ^{5-2,4-cyclopentadiene-1-yl)} [(1,2,3,4,5,6-η) - (1- methylethyl) benzene] - iron (1+) hexafluorophosphate ( 1-)) (manufactured by Ciba Geigy), CD-1010, CD-1011, CD-1012 (4- (2-hydroxytetradecanyloxy) diphenyliodonium hexafluoroantimonate) (above, manufactured by Sartomer), CI- 2481, CI-2624, CI-2639, CI-2064 (manufactured by Nippon Soda), Dekacure K126 (bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluorophosphate) (manufactured by Tegusa), RHODOLSIL PHOTOINITIATOR 2074 ((Tricumyl) iodonium tetrakis (pen Tafluorophenyl) borate) (manufactured by Rhodia) and the like.

  Examples of radical polymerization initiators include thioxanthones such as benzophenone, thioxanthone, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, and 2,4-dichlorothioxanthone, and benzoins such as benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether. Ethers, benzyldimethyl ketals such as 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) ) -2-hydroxy-2-methylpropan-1-one, α-hydroxyalkylphenones such as 1-hydroxycyclohexyl phenyl ketone, and α-dicarbonyl compounds such as camphorquinone. The radical polymerization initiator is preferably used in an amount of 0.1 to 20 parts by mass with respect to 100 parts by mass of the photocurable composition.

  Examples of the organic solvent include toluene, methyl ethyl ketone, acetone, ethylene glycol monoethyl ether, terpene, dioxane, cyclohexane, normal hexane, normal heptane, methyl alcohol, ethyl alcohol, mineral spirit and the like.

  The binder, conductive filler, polymerization initiator, and solvent as described above are dispersed and mixed using a high-speed impact mill, a high-speed impeller, or the like to obtain a conductive slurry. Specifically, first, under red light, a binder and a polymerization initiator are mixed to prepare a medium viscosity liquid, and a solvent is added to the medium to prepare a low viscosity liquid. Finally, a conductive slurry is obtained by adding a conductive filler to the low viscosity liquid while sufficiently applying a shearing force using a high speed mill or the like.

  In the application step of step S3, the prepared conductive slurry is applied to the surface of the metal thin plate 30 with a predetermined thickness. As a specific coating method, an existing method can be used, but it is preferable to use a dipping method, a doctor blade method, or a curtain coating method. The thickness of the conductive slurry in the coating step is preferably about 200 μm to 500 μm.

  The dipping method is a method of immersing a member to be coated in a coating solution. When applied to the present invention, the dipping method is performed by immersing the surface-treated metal thin plate 30 in a conductive slurry. The thickness of the applied conductive slurry can be controlled by adjusting the composition and temperature of the conductive slurry, the immersion time, the pulling speed, and the like.

  The doctor blade method is a method in which a coating liquid is placed in a tank and a so-called weir called a doctor blade is opened while moving the member to be coated. It can be applied with a different thickness. When applied to the present invention, the conductive slurry is placed in a tank and the surface-treated metal thin plate 30 is moved to perform application. The thickness of the applied conductive slurry can be controlled by adjusting the composition and temperature of the conductive slurry, the doctor blade height, the moving speed of the metal thin plate 30, and the like.

  The curtain coating method is a method in which a coating liquid is dropped into a curtain shape and a member to be coated is passed through it. When applied to the present invention, the conductive slurry is dropped into a curtain shape and the surface-treated metal is dropped into the curtain. Application is performed by passing the thin plate 30. The thickness of the applied conductive slurry can be controlled by adjusting the composition and temperature of the conductive slurry, the falling speed of the conductive slurry, the passing speed of the metal thin plate 30, and the like.

  Particularly, industrially, it is preferable to apply the surface treatment to a long metal thin plate by a dipping method.

  In the coating layer forming step of step S4, the solvent contained in the applied conductive slurry is removed to form a coating layer. Here, the coating layer is a layer in a state where the solvent contained in the conductive slurry is removed, that is, a layer made of a nonvolatile component such as a binder, a conductive filler, and a polymerization initiator.

  As a method for removing the solvent, an existing method can be used, but a drying method by blowing warm air is preferable. Specifically, hot air having a predetermined temperature is sprayed on the surface of the applied conductive slurry, and the solvent is evaporated to dry. The temperature of the hot air may be selected according to the solvent contained, regardless of whether an organic solvent type slurry or an aqueous type slurry is used.

  In the molding step of step S5, a molding layer in which a flow path is provided in the coating layer is formed by a stamper. The molding layer is a layer in a state before being cured as a resin layer, and has a channel groove and is formed in substantially the same shape as the target resin layer 32.

  A stamper (die) is pressed against the coating layer, and the uneven pattern formed on the stamper is transferred. The stamper may be a flat plate or may be gently curved. Further, since the stamper is a mold for forming the coating layer, the stamper only needs to have a mechanical strength equal to or lower than that of a pressing mold such as a metal sheet. For example, an aluminum alloy can be used for small-scale production such as trial production, and an SS steel (general structural rolled steel) can be used for mass production.

  The coating layer is non-tacky, but the surface tackiness increases when the stamper is pressed, and the surface of the coating layer may be roughened during release. Therefore, it is desirable that the contact portion of the stamper with the coating layer is non-adhesive to improve the releasability. Non-adhesive processing includes, for example, processing for attaching Teflon (registered trademark) particles in micro cracks of chrome plating, processing for forming a DLC (Diamond Like Carbon) film, titanium nitride, titanium carbide, titanium carbonitride, titanium oxide Examples thereof include a process for forming a ceramic film such as aluminum titanium nitride and chromium nitride, a process for forming a hard film by plasma source ion implantation, and a process for hardening the surface by electric discharge. In particular, for the coating layer, it is preferable to form a chromium nitride film on the stamper surface.

  In the molding layer curing step of step S6, the molding layer provided with the flow path is cured by combining the photocuring process and the thermosetting process. First, the surface layer portion of the molding layer is cured by photocuring treatment, and the entire molding layer is cured by thermosetting treatment.

  Since the molding layer includes a large amount of conductive filler, the irradiated light is cured only to the depth reached in the printing ink layer only by the photocuring treatment. Further, in the thermosetting treatment, the stamper-molded flow path is deformed by heat dripping. Therefore, it is effective to harden the surface layer portion of the molding layer in advance by light irradiation and to cure the entire layer by heating.

  In photocuring, when ultraviolet rays are used as irradiation light, the energy for curing is large because the wavelength is short, but the depth of reach is shallow, and it is not suitable for curing a thick film as in the present invention. Therefore, it is desirable to irradiate light having a wavelength of visible light to near infrared light. Moreover, it is desirable to combine a radical polymerization reaction and a cationic polymerization reaction and to cure in a short time with a simple operation.

In thermosetting, heating by a heating furnace and electromagnetic wave heating by electromagnetic wave irradiation are desirable.
In the substrate processing step, the coating step, the coating layer forming step, the molding step, and the molding layer curing step, the metal thin plate may be supplied in a roll shape or supplied in a piece shape that has been cut in advance to the outer dimensions of the separator. Also good.

  In the seal portion forming step in step S7, a seal protrusion is formed in a region corresponding to the seal portion 14 by press working. As shown in FIG. 5, when the PEFC is assembled, the shape of the seal protrusion is determined so that the seal protrusion is pressed against the polymer film 20 by the spring force, and the seal protrusion having the shape determined by press working is formed. When the metal thin plate is supplied in the form of a roll, in the seal portion forming step, the seal protrusion is formed by one press, and the separator 1 is obtained by punching out to the outer size of the separator. Further, the formation of the seal protrusion and the outer dimension punching may be performed by two successive presses.

  The separator 1 obtained as described above is alternately laminated with the fuel cells 2 in the assembly process, and further, a current collecting plate 3, an insulating sheet 4, an end flange 5 and an electrode wiring 12 are added to FIG. It is assembled as a PEFC 100 configured as shown.

As described above, by forming the flow path in the resin layer 32 by stamper molding in the coating layer, the dimensional accuracy is higher than that in the conventional press working, and warpage and distortion do not occur. Therefore, the productivity of the separator can be improved and a high yield can be realized.
Moreover, it is good also as a structure which provided the coating layer between the resin layer 32 and the metal thin plate 30. FIG.

  FIG. 7 is an enlarged view of a main part of the separation part 13 when the covering layer 33 is provided, and FIG. 8 is an enlarged view of a main part of the seal part 14 when the covering layer 33 is provided. By covering the surface of the metal thin plate 30 with the coating layer 33 in the separation unit 13, surface changes such as corrosion due to hydrogen gas, oxygen gas, and cooling water can be effectively prevented.

  Since the coating layer 33 is also required to have conductivity like the resin layer 32, the rubber includes, for example, general-purpose rubbers such as isoprene rubber, butadiene rubber, styrene-butadiene rubber, butyl rubber and ethylene-propylene rubber, A material obtained by adding a conductive filler to a special rubber such as epichlorohydrin rubber having gas permeability and heat resistance can be used. In particular, an allyl addition polymerization type polyisobutylene excellent in heat resistance and acid resistance is preferably added with a carbon filler.

  In addition, as the synthetic resin, a resin obtained by adding a conductive filler to a phenol resin, an epoxy resin, a fluorine-containing resin, or the like can be used. In particular, a fluorine-containing resin excellent in corrosion resistance is preferable. For example, PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer). Polymer), EPE (tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer), ETFE (tetrafluoroethylene-ethylene copolymer), PCTFE (polychlorotrifluoroethylene), ECTFE (chlorotrifluoroethylene). -Ethylene copolymer), PVDF (polyvinylidene fluoride), PVF (polyvinyl fluoride), THV (tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer), VD -HFP (vinylidene fluoride - hexafluoropropylene copolymer), TFE-P (vinylidene fluoride - propylene copolymer) is preferably obtained by adding carbon filler or the like.

  Further, when the sealing portion 14 is covered with the covering layer 33 that is an elastic body, the top portion 18 is pressed by the spring force, so that the contact portion is deformed and no gap is formed between the surface of the polymer film 20 and the sealing performance. Is further improved.

In the manufacturing process, the coating layer 33 is formed after the adhesive layer 31 is formed in the substrate processing process of step S1. The thing in the state in which the coating layer 33 was formed is called a coating substrate. The vulcanization treatment of the coating layer 33 by heating may be performed in the substrate processing step, or may be performed simultaneously with the curing of the resin layer 32 in the molding layer curing step.
Furthermore, the separator 1 may have a configuration in which a highly conductive layer is provided on the surface of the resin layer 32.

  FIG. 9 is an enlarged view of a main part of the separation part 13 when the high conductive layer 34 is provided. The highly conductive layer 34 is formed only in the region in contact with the catalyst electrode 21 on the surface of the resin layer 32.

  When the contact resistance between the resin layer 32 and the catalyst electrode 21 is high and a sufficient power recovery rate cannot be obtained, the contact resistance with the catalyst electrode 21 is formed by forming the highly conductive layer 34 on the surface of the resin layer 32. The recovery rate can be improved. It is preferable to use a mixture of a binder resin and carbon (hereinafter referred to as “carbon / resin compound”) for the highly conductive layer 34. The highly conductive layer 34 achieves high conductivity with carbon and reduces gas permeability with a binder resin. As the carbon content of the carbon / resin compound increases, the electrical resistance of the highly conductive layer 34 decreases. However, since the binder resin content decreases, the gas permeability increases. From the balance between electric resistance and gas permeability, the resin content of the carbon resin compound is preferably in the range of 20 to 30%. As carbon to be contained, artificial graphite, carbon fiber, carbon nanotube, fullerene and the like are used, and it is particularly preferable to use artificial graphite. As the binder resin, polyisobutylene rubber or the like is preferably used.

  In addition, the highly conductive layer 34 may be applied only to a region in contact with the catalyst electrode 21 on the surface of the resin layer 32. A reduction in contact resistance due to the high conductive layer 34 is sufficiently effective if the high conductive layer 34 is formed only in the contact region between the resin layer 32 and the catalyst electrode 21. Therefore, the formation region of the high conductive layer 34 can be reduced, and the contact resistance can be effectively reduced with a small amount of carbon / resin compound.

  In the production process, a highly conductive layer forming step is performed during the molding layer curing step or after the molding layer curing step. In the highly conductive layer forming step, a carbon / resin compound is applied to the surface of the resin layer 32 with a predetermined thickness. In the molding layer curing step, the resin layer 32 is subjected to a photocuring process. Therefore, if the carbon / resin compound is applied before the molding layer curing step, the resin layer 32 is difficult to cure. Therefore, when performing during a molding layer hardening process, it may carry out after performing a photocuring process and before performing a thermosetting process.

  Further, since the highly conductive layer 34 can be sufficiently effective even if it is a thin film layer, when the printing ink layer after the molding process is in a wet state, an alcohol dispersion of carbon particles is sprayed to several μm. It can also be formed in a simple process by spraying to a thickness and then drying and solidifying.

  As described above, in the separator 1, the resin layer 32 for providing the gas flow path in the separation unit 13 is formed by applying the conductive slurry and drying, and then forming the flow path by stamper molding, so that the conventional press working is performed. Compared with, the dimensional accuracy is high, and no warping or distortion occurs. Therefore, the productivity of the separator 1 can be improved and a high yield can be realized. Furthermore, the degree of freedom in designing the flow path pattern to be formed is greatly improved. For example, in the case of press working, the pattern design is limited because the pattern is formed integrally with the front and back and the number of linear patterns increases. However, stamper molding forms completely different patterns on each surface of the separator 1. It is also possible to form curved and hole-shaped patterns. Moreover, the seal part 14 is formed by press work, and can achieve high sealing performance with simple processing.

  Furthermore, since the contact resistance between the catalyst electrode 21 and the separator 1 can be greatly reduced by providing the highly conductive layer 34 in the separation portion 13, the power recovery rate can be further improved.

  FIG. 10 is a horizontal sectional view of the unit battery 101 including the other separator 1. As shown in the figure, in one separator 1 of the unit battery 101, the cross section of the seal protrusion may be trapezoidal so that the seal protrusion is in surface contact with the polymer film 20. In addition, as shown in FIG. 11, in both separators 1 of the unit battery 101, the cross section of the seal protrusion may be trapezoidal so that the seal protrusion is in surface contact with the polymer film 20.

In the above description, a thin metal plate is used as the core material of the separator 1, but a highly conductive and high strength resin such as a highly conductive carbon fiber reinforced resin (CFRP) may be used.
The separator 1 was produced on the conditions shown in the following Example.

  As the stamper, those made of an aluminum alloy and having a chromium nitride film formed on the surface in order to improve releasability were commonly used in Examples 1-3.

  Moreover, the coated substrate which apply | coats electroconductive slurry was shared in each Example, and it produced in the following procedures. The passive layer on the surface of the thin metal plate made of SUS304 (length 10 cm, width 10 cm, thickness 0.2 mm) was removed by sandblasting, and immediately immersed in a triazine thiol solution to form an adhesive layer. Next, a mixture of 100 parts by weight of allylic addition polymerization type polyisobutylene and 400 parts of conductive carbon graphite was applied to the surface of the surface-treated metal thin plate at a thickness of 50 μm and cured at 130 ° C. for 2 hours. Thus, a coating layer was formed.

Example 1
In Example 1, the resin layer 32 was formed of an acrylic / epoxy IPN structure resin.

Conductive slurry composition Binder: 70 parts by weight of acrylate oligomer (hexanediol diacrylate, manufactured by UCB Chemical Co., product name HDDA), 30 parts by weight of epoxy oligomer (epoxidized soybean oil, product of CP HALL, product name Paraplex G-62) Conductive filler: 300 parts by weight of spherical graphite (manufactured by Nippon Graphite Industry), 150 parts by weight of conductive carbon black (manufactured by Tokai Carbon, product name # 5500), 300 parts by weight of scaly graphite (manufactured by Chuetsu Graphite Industry, product name BF series) Catalyst: 1.5 parts by weight of hydroxyphenyl ketone (product name: Daro cure 1173, manufactured by Ciba), 1.0 part by weight of triallylsulfonium hexafluoride (product name: Cyracure UVI-6990, manufactured by Dow Chemical Company) Solvent: Toluene 6 parts by weight, methyl ethyl ketone 4 weights

  In addition, content of a solvent is content when what mixed a binder, an electroconductive filler, and a polymerization catalyst is 100 weight part.

Curing conditions Light irradiation was performed using a metal halide lamp at an output of 600 mW / cm ² .
Primary irradiation: Irradiation for 10 seconds Secondary irradiation: Irradiation at 100 ° C for 10 minutes

(Example 2)
In Example 2, the resin layer 32 was formed of vinyl ester (epoxy acrylate).

Conductive slurry composition Binder: 100 parts by weight of acrylate oligomer (Bisphenol A diacrylate, Showa High Polymer, product name Lipoxy SP1507) Conductive filler: 300 parts by weight of spherical graphite (manufactured by Nippon Graphite Industry), conductive carbon black (Tokai Carbon) Manufactured, product name # 5500) 150 parts by weight, scaly graphite (manufactured by Chuetsu Graphite Industry Co., Ltd., product name BF series) 300 parts by weight Polymerization catalyst: dye / borate 2-photon type (PII type) photopolymerization initiator α-diketone 3 parts by weight, Tertiary amine 0.5 parts by weight Solvent: 4 parts of toluene, 4 parts of methyl ethyl ketone, 3 parts of normal hexane

  In addition, content of a solvent is content when what mixed a binder, an electroconductive filler, and a polymerization catalyst is 100 weight part.

Curing conditions Light irradiation was performed using a xenon lamp at an output of 500 mW / cm ² .
Primary irradiation: Irradiation for 20 seconds Secondary irradiation: Irradiation at 100 ° C for 7 minutes

Example 3
In Example 3, the resin layer 32 was formed of an acrylic / epoxy IPN structure resin.

Conductive slurry composition Binder: Acrylate oligomer (Bisphenol A diacrylate, Showa High Polymer, product name Lipoxy SP1507) 50 parts by weight, Epoxy oligomer (Bis cyclic aliphatic diepoxy, Ciba, product name Araldite GY-179)
Conductive filler: 300 parts by weight of spherical graphite (manufactured by Nippon Graphite Industry), 150 parts by weight of conductive carbon black (manufactured by Tokai Carbon, product name # 5500), 300 parts by weight of scaly graphite (manufactured by Chuetsu Graphite Industry, product name BF series) Catalyst: 1.3 parts by weight of bisacylphosphine oxide (manufactured by Ciba, product name Irgacure819), 1.5 parts by weight of triallylsulfonium hexafluoride (manufactured by Dow Chemical Co., product name Cyracure UVI-6990) Solvent: 6 parts by weight of toluene, 4 parts by weight of methyl ethyl ketone

  In addition, content of a solvent is content when what mixed a binder, an electroconductive filler, and a polymerization catalyst is 100 weight part.

Curing conditions Light irradiation was performed using a metal halide lamp at an output of 800 mW / cm ² .
Primary irradiation: Irradiation for 7 seconds Secondary irradiation: Irradiation for 10 minutes while maintaining at 100 ° C. Table 1 shows mechanical and electrical characteristics of each example.

  In addition, when the printing ink layer after the resin layer printing process is in a wet state, the contact resistance value is obtained by spraying an ethyl alcohol dispersion of conductive carbon black (product name # 5500, manufactured by Tokai Carbon Co., Ltd.) with a dry film thickness of 2 It measured using what formed the highly conductive layer by spraying so that it might become thickness of -3micrometer, and making it harden | cure after that.

(Characteristic evaluation method)
Specific volume resistance value: Conforms to 4-probe method (JIS K7194) Contact resistance value: Electric resistance meter (ohm meter)
Hardness: The value measured by the microhardness meter is converted to [Shore D]

  12 is a schematic cross-sectional view of the separator obtained in Example 1. FIG. The width a of the convex portion in contact with the catalyst electrode was 2.0 mm, the width b of the concave portion serving as the fluid flow path was 2.0 mm, the thickness c of the convex portion was 0.45 mm, and the thickness of the concave portion was 0.1 mm. Further, the concave portion serving as the flow path had an inverted trapezoidal cross section, and the angle θ between the bottom surface and the side surface was 135 °.

  The separators produced according to Examples 1 to 3 were homogeneous with no uncured part and good transferability from the stamper. Further, as shown in Table 1, mechanical characteristics and electrical characteristics that sufficiently function as a separator were obtained.

1 is a perspective view schematically showing a polymer electrolyte fuel cell (PEFC) 100 in a developed state. FIG. 2 is a horizontal sectional view of a unit battery 101 including a separator 1. FIG. FIG. 3 is an enlarged view of a main part of a separation unit 13 of the separator 1. FIG. 4 is an enlarged view of a main part of a seal part 14 of the separator 1. It is a figure explaining the shape of the seal part 14 for a spring force to generate | occur | produce. It is a manufacturing process figure which shows the manufacturing method of the separator which is one Embodiment of this invention. It is a principal part enlarged view of the isolation | separation part 13 when the coating layer 33 is provided. It is a principal part enlarged view of the seal | sticker part 14 when the coating layer 33 is provided. It is a principal part enlarged view of the isolation | separation part 13 when the highly conductive layer 34 is provided. 3 is a horizontal sectional view of a unit battery 101 including another separator 1. FIG. 3 is a horizontal sectional view of a unit battery 101 including another separator 1. FIG. 1 is a schematic cross-sectional view of a separator obtained by Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Separator 2 Fuel cell 3 Current collector plate 4 Insulation sheet 5 End flange 6 Hydrogen gas supply port 7 Cooling water supply port 8 Oxygen gas supply port 9 Hydrogen gas discharge port 10 Cooling water discharge port 11 Oxygen gas discharge port 12 Electrode wiring 13 Separation part 14 Seal part 15 Separation block 16 Hydrogen gas flow path 17 Oxygen gas flow path 18 Bottom part 20 Polymer membrane 21 Catalytic electrode 30 Metal thin plate 31 Adhesive layer 32 Resin layer 33 Coating layer 34 High conductive layer 100 Solid polymer fuel cell (PEFC)
101 unit battery

Claims (10)

A method of manufacturing a separator having a separation portion that is interposed between a plurality of electrolyte assemblies provided with catalyst electrodes on a surface in a thickness direction of an electrolyte layer containing an electrolyte medium and separates a flow path of a fuel gas and an oxidant gas. ,
An application step of applying conductive slurry to the surface of the metal plate;
A coating layer forming step of forming a coating layer by removing the solvent contained in the coated conductive slurry;
A molding step of forming a molding layer with a flow path in the coating layer by a stamper;
A separator manufacturing method comprising: a molding layer curing step of curing a molding layer to form a resin layer.   The conductive slurry is obtained by mixing a binder made of a curable monomer, a curable oligomer or a curable prepolymer for forming a rubber or a synthetic resin, a conductive filler made of a metal compound or a carbon-based material, and a solvent. The method for producing a separator according to claim 1, wherein the separator is obtained.   3. The separator manufacturing method according to claim 1, wherein in the coating step, the conductive slurry is applied by a dipping method, a doctor blade method, or a curtain coating method.   The method for producing a separator according to any one of claims 1 to 3, wherein the coating layer forming step removes the solvent by blowing hot air to the applied conductive slurry and drying the applied slurry.   The separator according to any one of claims 1 to 4, further comprising a substrate processing step for performing a treatment for increasing adhesion to the coating layer on the surface of the metal plate before the coating step. Production method.   6. The separator manufacturing method according to claim 5, wherein in the substrate processing step, triazine thiol or polyaniline is diffused on the surface of the metal plate. A method of manufacturing a separator having a separation portion that is interposed between a plurality of electrolyte assemblies provided with catalyst electrodes on a surface in a thickness direction of an electrolyte layer containing an electrolyte medium and separates a flow path of a fuel gas and an oxidant gas. ,
A coating layer forming step of forming a coating layer made of conductive rubber or synthetic resin on the entire surface of the flat metal plate;
An application step of applying a conductive slurry to the surface of the coating layer;
A coating layer forming step of forming a coating layer by removing the solvent contained in the coated conductive slurry;
A molding step of forming a molding layer with a flow path in the coating layer by a stamper;
A separator manufacturing method comprising: a molding layer curing step of curing a molding layer to form a resin layer.   The production of a separator according to any one of claims 1 to 7, further comprising a highly conductive layer forming step of forming a highly conductive layer having conductivity higher than that of the resin layer on the surface of the resin layer. Method.   9. The method for manufacturing a separator according to claim 8, wherein in the high conductive layer forming step, the high conductive layer is formed at least in a region where the resin layer is in contact with the electrolyte assembly. The separator is provided on the outer peripheral portion, and has a seal portion that prevents leakage of fuel gas and oxidant gas,
A region corresponding to the seal portion is a seal protrusion that extends in parallel with the electrolyte layer exposed from the electrolyte assembly by pressing, and the top portion thereof is configured to be pressed against the electrolyte layer by a spring force. The method of manufacturing a separator according to claim 1, wherein a seal protrusion is formed.

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