Manufacturing method of fuel cell separator

Abstract

To manufacture a fuel cell separator having a constitution that two separator base materials are bonded with each other in a conducted state, with a high productivity.SOLUTION: A manufacturing method of a fuel cell separator, comprises a coating step, a setting step, and a compression hardening step. In the coating step, a first coating material 50a containing a first coupling material and a conductive particle is applied to both of opposite surfaces 34 and 44 in each of two base materials 31 and 41. In the setting step, the two base materials 31 and 41 are set to be a state where the first coating material 50a is held between the opposite surfaces 34 and 44, and a state where both of the opposite surfaces 34 and 44 are opposite. In the compression hardening step, the two base materials 31 and 41 are integrated by hardening the first coating material 50a in a state where the base materials 31 and 41 are compressed in an opposite direction.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a method for producing a separator for a fuel cell. [Background technology]

[0002] A polymer electrolyte fuel cell (hereinafter simply referred to as a fuel cell) has a plurality of unit cells. Each unit cell has two separators made of metal plates on which extending ridges and grooves are alternately provided. The unit cell has a configuration in which a power generation section including a membrane electrode assembly is sandwiched between the two separators. Gas flow paths through which fuel gas and oxidizing gas are supplied are defined and formed between each separator and the power generation section.

[0003] A fuel cell has a structure in which a plurality of unit cells are stacked. In the fuel cell described in Patent Document 1, adjacent separators are welded together to fix adjacent unit cells to each other. In this fuel cell, adjacent separators are welded together to provide electrical continuity, and therefore the internal resistance of the fuel cell is low. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-97969 A Summary of the Invention [Problem to be solved by the invention]

[0005] Due to the structure of the fuel cell, the gas flow path has a fine structure. Therefore, the separators that define the gas flow path also have a fine structure. For this reason, the welding process of welding adjacent separators together can be said to be a complicated process. Furthermore, after the welding process, a cleaning process for cleaning the separators and a surface treatment process for applying a surface treatment to the separators may be required to ensure the quality of the separators. Thus, if a manufacturing method of welding two separators together is adopted, the process involved in manufacturing the separators becomes complicated. This may lead to a decrease in the productivity of the fuel cell. [Means for solving the problem]

[0006] Various aspects of a method for manufacturing a fuel cell separator to solve the above problems will be described below. [Embodiment 1] A method for manufacturing a separator for a fuel cell, comprising two separator substrates made of a conductive material, each having alternating extending ridges and grooves, and the two separator substrates being stacked together to form an integrated unit, the method comprising: a coating step of applying a paint containing a binder made of a resin material and conductive particles to at least one of the opposing surfaces of each of the two separator substrates; a setting step of setting the two separator substrates after the coating step so that the paint is sandwiched between the opposing surfaces of each of the two separator substrates and the opposing surfaces face each other; and a pressure curing step of curing the paint while the two separator substrates are pressurized in the opposing direction of the opposing surfaces, thereby integrating the two separator substrates.

[0007] According to the above manufacturing method, two separator substrates are joined using a coating material applied to the surface of the separator substrate, so that the two separator substrates can be integrally formed in a stacked state without employing a complicated welding process. This makes it possible to manufacture the separator using a simple process since post-processing such as a cleaning process or a surface treatment process is not required, unlike when two separator substrates are joined by welding.

[0008] Moreover, when the paint is cured, the two separator substrates are pressed in the opposing direction, so that the conductive particles contained in the paint are pressed against the surfaces of the separator substrates. This allows the paint to be cured with the conductive particles sandwiched between the two separator substrates. Therefore, according to the above manufacturing method, although a bonding layer made of paint (more specifically, a binder) is formed between the two separator substrates, a conductive path that connects the two separator substrates is formed by the conductive particles contained in the paint.

[0009] In this way, according to the above-described manufacturing method, a fuel cell separator having a configuration in which two separator substrates are joined together in a conductive state can be manufactured with high productivity. [Aspect 2] A method for manufacturing a fuel cell separator as described in [Aspect 1], in which a thermosetting resin material is used as the resin material constituting the binder, and in the pressure curing process, the paint is cured by heating the paint together with the two separator substrates.

[0010] According to the above-mentioned manufacturing method, the two separator substrates with the coating material sandwiched therebetween are heated and pressurized, whereby the two separators can be integrated together. [Aspect 3] A method for manufacturing a fuel cell separator as described in [Aspect 1] or [Aspect 2], wherein in the coating step, the paint is applied to both opposing surfaces of each of the two separator substrates.

[0011] According to the above manufacturing method, in the setting step, paint can be placed between the two separator substrates, such as by bringing the paints that have already been applied to both opposing surfaces into contact with each other to integrate them. This allows the paint to be placed in a more balanced manner than when paint is applied to only one of the opposing surfaces, i.e., when paint is placed between the two separator substrates by bringing the paint that has already been applied to one opposing surface into contact with the other opposing surface. Therefore, the paint can be used to firmly bond the two separator substrates.

[0012] [Aspect 4] A method for producing a fuel cell separator according to any one of [Aspect 1] to [Aspect 3], wherein in the coating step, the paint is applied to both sides of each of the two separator substrates.

[0013] According to the above manufacturing method, the coating material can be cured on both sides of each of the two separator substrates in the pressure curing step, which not only integrates the two separator substrates via a bonding layer made of a cured binder, but also forms a coating layer made of the cured binder that covers the outer surface of each separator substrate. Effect of the Invention

[0014] According to the present invention, a fuel cell separator having a configuration in which two separator substrates are joined together in a conductive state can be produced with high productivity. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is an enlarged cross-sectional view of a fuel cell stack, focusing on a single cell having a separator, in one embodiment of a method for producing a fuel cell separator. [Diagram 2] 2 is a cross-sectional view of a fuel cell separator to which the manufacturing method of the embodiment is applied. FIG. [Diagram 3] 3 is an enlarged cross-sectional view showing a portion of the fuel cell separator indicated by an arrow 3 in FIG. 2. FIG. [Figure 4] 3 is an enlarged cross-sectional view showing a portion of the fuel cell separator indicated by an arrow 4 in FIG. 2. FIG. [Diagram 5] FIG. 2 is a cross-sectional view showing a state in which a first paint is applied to the surface of a substrate. [Figure 6] FIG. 2 is a cross-sectional view showing a state in which a first paint is applied to the surface of a substrate. [Figure 7] FIG. 4 is a cross-sectional view showing a state in which a second paint is applied to the film. [Figure 8]FIG. 4 is a cross-sectional view showing a state in which the film coated with the second paint is being rolled. [Figure 9] FIG. 4 is a cross-sectional view showing a state in which the film coated with the second paint is rolled. [Figure 10] FIG. 2 is a cross-sectional view showing a state in which a substrate and a film are set in a pressure curing device. [Figure 11] FIG. 2 is a cross-sectional view showing a state in which two base materials are integrated together. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, one embodiment of a method for producing a fuel cell separator will be described with reference to FIGS. In the drawings, for the convenience of explanation, some components may be shown exaggerated or simplified, and the dimensional ratios of each component may differ from the actual ones.

[0017] 1, the fuel cell separator of this embodiment (hereinafter referred to as separator 20) is used in a polymer electrolyte fuel cell stack 1. The separator 20 has a configuration in which a first separator 30 and a second separator 40, which will be described later, are integrally formed.

[0018] The stack 1 has a structure in which a plurality of unit cells 10 are stacked. The unit cell 10 includes a power generating section 11 sandwiched between a first separator 30 on the anode side and a second separator 40 on the cathode side.

[0019] The power generation section 11 is composed of a membrane electrode assembly 12, and an anode side gas diffusion layer 15 and a cathode side gas diffusion layer 16 that sandwich the membrane electrode assembly 12. The anode side gas diffusion layer 15 is provided between the membrane electrode assembly 12 and a first separator 30. The cathode side gas diffusion layer 16 is provided between the membrane electrode assembly 12 and a second separator 40. Both the anode side gas diffusion layer 15 and the cathode side gas diffusion layer 16 are formed of carbon fiber.

[0020] The membrane electrode assembly 12 includes an electrolyte membrane 13 made of a solid polymer material that has good proton conductivity in a wet state, and a pair of electrode catalyst layers 14 that sandwich the electrolyte membrane 13. Each electrode catalyst layer 14 supports a catalyst such as platinum to promote the electrochemical reaction of the reactant gas in the fuel cell.

[0021] <First separator> The first separator 30 has a substrate 31 formed in a plate shape from a material having electrical conductivity (hereinafter, conductive material) such as stainless steel. The substrate 31 is provided with first extending ridges 32 and first grooves 33 arranged alternately. A plurality of first ridges 32 and first grooves 33 are provided. Each of the first ridges 32 forms a ridge extending in parallel with a gap between them. Each of the first ridges 32 is in contact with the anode-side gas diffusion layer 15. Each of the first grooves 33 forms a groove extending along the first ridges 32 between two adjacent first ridges 32. In this embodiment, the substrate 31 corresponds to the separator substrate.

[0022] <Second separator> The second separator 40 has a substrate 41 formed in a plate shape from a conductive material such as stainless steel. The substrate 41 is provided with second protrusions 42 and second grooves 43 that extend alternately. A plurality of second protrusions 42 and second grooves 43 are provided. Each second protrusion 42 forms a protrusion that extends in parallel with a gap between them. Each second protrusion 42 is in contact with the cathode-side gas diffusion layer 16. Each second groove 43 forms a groove that extends along the second protrusion 42 between two adjacent second protrusions 42. In this embodiment, the substrate 41 corresponds to the separator substrate.

[0023] <1st bonding layer> 2 and 3, a first bonding layer 50 is formed on the entire surface of both sides of the substrate 31 of the first separator 30 and the entire surface of both sides of the substrate 41 of the second separator 40. The first bonding layer 50 includes a first bonding material 51 made of a thermosetting resin material and conductive particles 52. The first bonding material 51 includes, for example, an epoxy resin and a phenolic resin. The conductive particles 52 are, for example, titanium nitride. Note that titanium nitride has a higher hardness than the oxide coatings 31a and 41a formed on the surfaces of the substrates 31 and 41.

[0024] The substrate 31 of the first separator 30 and the substrate 41 of the second separator 40 are integrally formed via a first bonding layer 50. More specifically, in this embodiment, the first separator 30 and the second separator 40 share the first bonding layer 50 in a portion where the back surface of the first groove portion 33 and the back surface of the second groove portion 43 face each other. This makes the first separator 30 and the second separator 40 integral.

[0025] In this embodiment, in the portion where the back surface of the first groove portion 33 faces the back surface of the second groove portion 43, the conductive particles 52 contained in the first bonding layer 50 penetrate the oxide films 31a, 41a formed on the back surfaces of the groove portions 33, 43 and contact the substrates 31, 41. Therefore, a conductive path is formed between the substrate 31 of the first separator 30 and the substrate 41 of the second separator 40 by the conductive particles 52, which does not pass through the oxide films 31a, 41a.

[0026] <Second bonding layer> 2 and 4, a second bonding layer 60 is formed on a portion of the surface of the first bonding layer 50 that corresponds to the top surface of the second protrusion 42 of the base material 41. In addition, a second bonding layer 60 is formed on a portion of the surface of the first bonding layer 50 that corresponds to the top surface of the first protrusion 32 of the base material 31.

[0027] The second bonding layer 60 includes a second bonding material 61 made of a thermosetting resin material and a conductive carbon material 62. The second bonding material 61 includes, for example, an epoxy resin. The conductive carbon material 62 is, for example, graphite particles.

[0028] In this embodiment, in the portions of the substrate 31, 41 corresponding to the top surfaces of the protrusions 32, 42, the conductive particles 52 contained in the first bonding layer 50 penetrate the oxide films 31a, 41a formed on the surfaces of the protrusions 32, 42 and contact the substrate 31, 41. The conductive particles 52 and the conductive carbon material 62 are in contact with each other. Therefore, between the substrate 31 of the first separator 30 and the power generation section 11 (see FIG. 1), the conductive particles 52 and the conductive carbon material 62 form a conductive path that does not pass through the oxide film 31a. Also, between the substrate 41 of the second separator 40 and the power generation section 11, the conductive particles 52 and the conductive carbon material 62 form a conductive path that does not pass through the oxide film 41a.

[0029] In this embodiment, the first bonding layer 50 and the second bonding layer 60 are formed on the substrate 31 of the first separator 30 and the substrate 41 of the second separator 40, respectively. However, inside the stack 1, a conductive path is formed by the substrates 31 and 41, the conductive particles 52, and the conductive carbon material 62.

[0030] <Gas flow path, cooling water flow path> As shown in FIG. 1, a fuel gas flow path through which a fuel gas flows is formed in a portion defined by a portion corresponding to the first groove portion 33 of the first separator 30 and the anode side gas diffusion layer 15. An oxidizing gas flow path through which an oxidizing gas flows is formed in a portion defined by a portion corresponding to the second groove portion 43 of the second separator 40 and the cathode side gas diffusion layer 16. In this embodiment, the fuel gas is hydrogen, and the oxidizing gas is air. Furthermore, a cooling water flow path through which a cooling water flows is formed in a portion defined by a portion corresponding to the back surface of the first protrusion portion 32 of the first separator 30 and a portion corresponding to the back surface of the second protrusion portion 42 of the second separator 40.

[0031] <Manufacturing method> A method for producing the separator 20 of this embodiment will be described below. <Coating process> As shown in FIG. 5, first, a coating step is performed.

[0032] In the coating step, the first paint 50a is sprayed toward the base materials 31, 41 using the spray gun 100, so that the first paint 50a is coated on the surfaces of the base materials 31, 41. Here, the first paint 50a includes a first binder 51, conductive particles 52, a first solvent, a second solvent, and a curing accelerator. The second solvent has a boiling point lower than that of the first solvent. Therefore, the second solvent is more likely to volatilize than the first solvent.

[0033] The first solvent in this embodiment is, for example, butyl carbitol. The boiling point of the first solvent is about 230°C. The second solvent in this embodiment is, for example, methyl ethyl ketone (MEK). The boiling point of the second solvent is about 79°C. In this specification, the boiling point refers to the boiling point at normal temperature and normal pressure. The curing accelerator in this embodiment is, for example, Curesol (registered trademark).

[0034] By spraying the first paint 50a toward the substrates 31, 41 using the spray gun 100, the first paint 50a is exposed to normal temperature and pressure, causing the second solvent to volatilize from the first paint 50a. This volatilization of the second solvent occurs while the first paint 50a sprayed from the spray gun 100 is waiting to reach the surface of the substrates 31, 41. Therefore, when the first paint 50a reaches the surface of the substrates 31, 41, most of the second solvent has already volatilized from the first paint 50a.

[0035] Therefore, in this embodiment, the first paint 50a is applied to the surfaces of the substrates 31, 41 while volatilizing the second solvent when applying the first paint 50a (application step). As shown in Fig. 6, in this embodiment, the first paint 50a is applied to the surfaces of the substrates 31, 41, more specifically, to both surfaces in the thickness direction (the vertical direction in Fig. 6). As a result, in this embodiment, the first paint 50a is applied to both of the opposing surfaces 34, 44 of each of the two substrates 31, 41. Then, the substrates 31, 41 are dried at a predetermined temperature lower than the thermal curing temperature of the first binder 51 (drying step).

[0036] <Film formation process> Furthermore, as shown in FIGS. 7 to 9, a film forming process is carried out. In the film forming step, a film member 70 (FIG. 9) to be used in forming the second bonding layer 60 is formed.

[0037] As shown in Fig. 7, first, a resin film 71 is conveyed by a conveying device (not shown), and a second paint 60a is applied to one surface of the film 71 in the thickness direction using a coater 110. Here, the second paint 60a contains a second binder 61, a conductive carbon material 62, and a solvent. The solvent for the second paint 60a in this embodiment is, for example, N-methyl-2-pyrrolidone. The film 71 is formed of a resin material such as polyethylene terephthalate (PET).

[0038] As shown in FIG. 8, thereafter, the film 71 coated with the second coating material 60a is rolled by passing it between a first roller 121 and a second roller 122 which face each other and rotate in opposite directions. The first roller 121 in this embodiment is made of a metal material such as stainless steel. The surface of the first roller 121 is subjected to a surface treatment such as chrome plating. The second roller 122 in this embodiment is made of an elastomer such as rubber. In the rolling step, the film 71 is brought into contact with the first roller 121, and the second coating material 60a is brought into contact with the second roller 122.

[0039] 9, the rolling process reduces the thickness of the second paint 60a applied to the film 71. This reduces the gaps between the conductive carbon materials 62 in the second paint 60a. In this manner, the film member 70 is formed in the film forming process.

[0040] <Setting process> After the coating step and the film forming step, a setting step is carried out. In the setting step, the base materials 31, 41 having the first coating material 50a applied on both sides and the two film members 70 are set inside the pressure curing device 130.

[0041] As shown in FIG. 10, the pressure hardening device 130 includes a first mold 131 and a second mold 132 arranged opposite the first mold 131. The second mold 132 is a fixed mold, and the first mold 131 is a movable mold arranged to be movable toward and away from the second mold 132. An electric heating wire 133 and an electric heating wire 134 are provided inside the first mold 131 and the second mold 132, respectively. By passing electricity through the electric heating wires 133 and 134, the first mold 131 and the second mold 132 are heated to a predetermined temperature. The predetermined temperature is a temperature at which the first binder 51 and the second binder 61, which are thermosetting resins, are thermally hardened.

[0042] In the setting step, the substrates 31 and 41 and the two film members 70 are set so that they are stacked and arranged in the order of the film member 70, substrate 41, substrate 31, and film member 70 from the second mold 132 side. At this time, the second mold 132 and the film 71 of the film member 70 are in contact with each other, and the first paint 50a of the substrate 41 and the second paint 60a of the film member 70 are in contact with each other. In addition, the two substrates 31 and 41 are in a state in which the first paint 50a is sandwiched between their opposing surfaces 34 and 44, and their opposing surfaces 34 and 44 are opposed to each other. Furthermore, between the first mold 131 and the substrate 31, the first paint 50a of the substrate 31 and the second paint 60a of the film member 70 are in contact with each other.

[0043] <Pressure curing process> After the setting step, a pressure curing step is carried out. In the pressure curing process, the substrates 31, 41 having the first paint 50a applied on both sides and the two film members 70 are pressurized in opposing directions, and the first paint 50a and the second paint 60a of the film members 70 are cured to integrate the two substrates 31, 41.

[0044] Specifically, as shown in FIG. 11, the pressure curing device 130 is clamped. As a result, the two substrates 31, 41 and the two film members 70 are pressed in a manner that they are sandwiched between the first mold 131 and the second mold 132. At this time, the conductive particles 52 contained in the first paint 50a are pressed against the surfaces of the substrates 31, 41. As a result, the conductive particles 52 penetrate the oxide film 31a and come into contact with the substrate 31, and the conductive particles 52 penetrate the oxide film 41a and come into contact with the substrate 41 (see FIG. 3 and FIG. 4). In addition, the second paint 60a of the film member 70 on the first mold 131 side is pressed and transferred to the surface of the first paint 50a of the substrate 31, and the second paint 60a of the film member 70 on the second mold 132 side is pressed and transferred to the surface of the first paint 50a of the substrate 41. The pressure curing device 130 applies pressure to the two base materials 31, 41 and the two film members 70 such that the base materials 31, 41 do not undergo plastic deformation.

[0045] When the pressurized hardening device 130 is clamped, the first mold 131 and the second mold 132 are heated to a predetermined temperature by passing electricity through the heating wires 133 and 134. Therefore, the first binder 51 of the first paint 50a is thermally hardened to form a first bonding layer 50 on the surfaces of the substrates 31 and 41. In this embodiment, the two substrates 31 and 41, and thus the first separator 30 and the second separator 40, are integrated through the first bonding layer 50. In addition, the second binder 61 of the second paint 60a is thermally hardened to form a second bonding layer 60 on the surface of the first bonding layer 50.

[0046] Finally, the pressure curing device 130 is opened to remove the integrated first separator 30 and second separator 40, and the film 71 is peeled off from the first separator 30 and the second separator 40. In this manner, the separator 20 is manufactured.

[0047] <Action of this embodiment> According to this embodiment, the two base materials 31, 41 can be joined together using the first paint 50a applied to the surfaces of the base materials 31, 41. This allows the two base materials 31, 41, and therefore the two separators 30, 40, to be integrally formed in a stacked state without employing a complicated welding process. Therefore, unlike the case where the two separators are joined by welding, post-processing such as a cleaning process or a surface treatment process is not required, and the first separator 30 and the second separator 40 can be manufactured in a simple process.

[0048] In this embodiment, the first paint 50a contains a first binder 51 made of a thermosetting resin material. Then, in a state where the first paint 50a is sandwiched between the two base materials 31, 41, the first paint 50a is heated together with the base materials 31, 41. As a result, the first binder 51 contained in the first paint 50a is thermally cured between the two base materials 31, 41 to form a first bonding layer 50. Then, by bonding to each other with the first bonding layer 50, the two base materials 31, 41, and thus the two separators 30, 40, can be integrated.

[0049] In this embodiment, the first paint 50a is applied to both sides of each of the two substrates 31, 41. Therefore, in the pressurizing and curing step, the first binder 51 contained in the first paint 50a can be thermally cured on both sides of each of the two substrates 31, 41. As a result, when the first paint 50a is thermally cured between the substrates 31, 41 to integrate the two substrates 31, 41, the first paint 50a is also thermally cured on the entire outer surface of each substrate 31, 41, so that a coating layer that covers and protects the outer surface of each substrate 31, 41 can be formed. In this way, according to this embodiment, the step of joining the substrates 31, 41 and the step of forming a coating layer on the surface of the substrate 31, 41 can be simultaneously performed in the pressurizing and curing step.

[0050] In this embodiment, the first paint 50a is applied to both of the opposing surfaces 34, 44 of each of the two substrates 31, 41. Therefore, in the setting step, when the two substrates 31, 41 are set inside the pressure curing device 130, the opposing surface 34 of the substrate 31 and the opposing surface 44 of the substrate 41 are aligned, so that the first paint 50a of each opposing surface 34, 44 comes into contact and becomes one. In this manner, the first paint 50a is disposed between the opposing surfaces 34, 44 of each of the two substrates 31, 41. Therefore, compared to the case where the first paint 50a applied in advance to one of the opposing surfaces 34, 44 is placed by contacting the other of the opposing surfaces 34, 44, it is possible to place the first paint 50a between the two substrates 31, 41 in a well-balanced manner. Therefore, the first binder 51 contained in this first paint 50a can firmly bond the two substrates 31, 41.

[0051] In this embodiment, in the pressure curing step, the two substrates 31, 41 and the two film members 70 are pressed in the opposing direction (the vertical direction in FIG. 11), so that the conductive particles 52 contained in the first paint 50a are pressed against the surfaces of the substrates 31, 41. This allows the first paint 50a to be cured in a state in which the conductive particles 52 are sandwiched between the two substrates 31, 41. According to this embodiment, although the first bonding layer 50 made of the first paint 50a (more specifically, the first binder 51) is formed between the two substrates 31, 41, the conductive particles 52 contained in the first paint 50a can form a conductive path that conducts the two substrates 31, 41. Therefore, by assembling the stack 1 using the separator 20 of this embodiment having the substrates 31, 41, the internal resistance of the stack 1 can be reduced.

[0052] According to this embodiment, in this manner, the separator 20 having the two base materials 31, 41 bonded to each other in an electrically conductive state can be manufactured with high productivity. According to this embodiment, the following effects can be obtained.

[0053] (1) The manufacturing method of this embodiment includes a coating step, a setting step, and a pressure curing step. In the coating step, a first coating material 50a containing a first binder 51 and conductive particles 52 is applied to both of the opposing surfaces 34, 44 of each of the two substrates 31, 41. In the setting step, the two substrates 31, 41 are set in a state in which the first coating material 50a is sandwiched between the opposing surfaces 34, 44 and the opposing surfaces 34, 44 face each other. In the pressure curing step, the first coating material 50a is cured while the two substrates 31, 41 are pressed in the opposing direction, thereby integrating the two substrates 31, 41.

[0054] According to this embodiment, the separators 30, 40 each having a configuration in which two base materials 31, 41 are joined to each other in a conductive state can be manufactured with high productivity. (2) The first binder 51 is made of a thermosetting resin material. In the pressure curing step, the first paint 50a is heated together with the two base materials 31, 41 to cure the first paint 50a. According to this embodiment, the two base materials 31, 41 with the first paint 50a sandwiched therebetween are heated and pressurized, thereby integrating the two base materials 31, 41.

[0055] (3) In the coating step, the first paint 50a is applied to both of the opposing surfaces 34, 44 of the two base materials 31, 41. This allows the first paint 50a to be disposed in a well-balanced manner between the two base materials 31, 41, and the first binder 51 contained in the first paint 50a can firmly bond the two base materials 31, 41.

[0056] (4) In the coating step, the first coating material 50a is applied to both sides of each of the two base materials 31, 41. Therefore, when the first coating material 50a is thermally cured between the base materials 31, 41 to integrate the two base materials 31, 41, the first coating material 50a is also thermally cured on the entire outer surface of each base material 31, 41, so that a coating layer that covers and protects the outer surface of each base material 31, 41 can be formed.

[0057] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0058] The first roller 121 and the second roller 122 may be made of a metal material other than stainless steel, or may be made of an elastomer such as rubber.

[0059] In the above embodiment, the first paint 50a is applied to the surface of the substrate 31, 41 using the spray gun 100, but the first paint 50a can also be applied to the surface of the substrate 31, 41 by immersing the substrate 31, 41 in a tank in which the first paint 50a is stored.

[0060] The type of the first solvent and the type of the second solvent may be changed as appropriate. The first binder 51 and the second binder 61 may contain other thermosetting resins instead of or in addition to the epoxy resin or phenol resin.

[0061] A thermoplastic resin material may be used as the first binder 51 and the second binder 61. In this case, in the pressure hardening step, the first binder 51 and the second binder 61 may be hardened by being cooled by leaving them for a predetermined time inside the pressure hardening device or by forced cooling.

[0062] Instead of or in addition to the graphite particles, other conductive carbon materials 62 such as carbon black may be used. Instead of titanium nitride, other conductive particles 52 such as titanium carbide or titanium boride can be used.

[0063] The base material 31, 41 may be made of a metal material other than stainless steel. Examples of such metal materials include titanium alloys, aluminum alloys, and magnesium alloys. In addition, the base material 31, 41 may be made of a conductive material other than a metal material, such as a conductive resin material.

[0064] The method for manufacturing a fuel cell separator according to the above embodiment can also be applied to a separator that does not have the second bonding layer 60. In the coating step, the first coating material 50a may be applied only to the opposing surface 34 of the substrate 31. In the coating step, the first coating material 50a may be applied only to the opposing surface 44 of the substrate 41.

[0065] In the coating step, the first paint 50a may be applied to only one of the opposing surface 34 of the base material 31 and the opposing surface 44 of the base material 41. [Explanation of symbols]

[0066] 10...Single cell 11…Power generation section 12...Membrane electrode assembly 13...Electrolyte membrane 14...electrode catalyst layer 15...Anode side gas diffusion layer 16…Cathode side gas diffusion layer 20…Separator 30…First separator 31...Base material 31a...Oxide film 32…First protrusion 33…First groove 34…Opposite surface 40…Second separator 41...Base material 41a...Oxide film 42…Second protrusion 43…Second groove 44…Opposite surface 50...First bonding layer 50a…First paint 51...First binding material 52...Conductive particles 60…Second bonding layer 60a…2nd paint 61...Second binding material 62...Conductive carbon material 70...Film material 71...Film 100…Spray gun 110…Coater 121…First roller 122…Second roller 130...Pressure hardening device 131…Type 1 132…2nd type 133,134…Heating wire

Claims

1. A method for manufacturing a separator for a fuel cell, comprising: two separator substrates made of a conductive material, each having extending ridges and grooves alternately provided thereon; and the two separator substrates being integrally formed in a stacked state, the method comprising the steps of: a coating step of coating at least one of the opposing surfaces of each of the two separator substrates with a coating material containing a binder made of a resin material and conductive particles; a setting step of setting the two separator substrates in a state in which the coating material is sandwiched between the opposing surfaces of the two separator substrates and the opposing surfaces of the two separator substrates face each other after the coating step; and a pressure curing step of, after the setting step, curing the coating material while the two separator base materials are pressed in the opposing direction of the opposing surfaces, thereby integrating the two separator base materials. A method for manufacturing a separator for a fuel cell.

2. A thermosetting resin material is used as the resin material constituting the binder, In the pressurizing and curing step, the paint is cured by heating the two separator substrates. A method for producing the fuel cell separator according to claim 1.

3. In the coating step, the coating material is applied to both of the opposing surfaces of each of the two separator substrates. A method for producing a fuel cell separator according to claim 1 or 2.

4. In the coating step, the coating material is applied to both surfaces of each of the two separator substrates. A method for producing a fuel cell separator according to claim 1 or 2.

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