JP3828521B2 - Fuel cell separator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a separator for a fuel cell comprising a cell module by attaching an anode side electrode and a cathode side electrode to an electrolyte membrane and sandwiching them from both sides.TAbout.
[0002]
[Prior art]
A fuel cell is a battery that utilizes the reverse principle of water electrolysis and can obtain electricity in the process of obtaining water by reacting hydrogen and oxygen. In general, hydrogen replaces fuel gas, and oxygen replaces air or oxidant gas, so the terms fuel gas, air, and oxidant gas are often used. Hereinafter, a general fuel cell will be described with reference to the following figure.
[0003]
FIG. 8 is an exploded perspective view showing a conventional fuel cell.
In the fuel cell 100, an anode side electrode 102 and a cathode side electrode 103 are attached to an electrolyte membrane 101, and these electrodes 102 and 103 are sandwiched between a first separator 106 and a second separator 107 via diffusion layers 104 and 105. Configure the cell module. A fuel cell is obtained by stacking a large number of the cell modules.
[0004]
Here, it is necessary to effectively contact the oxidant gas with the cathode side electrode 103. Therefore, a plurality of grooves 108 are provided on the surface 107 a of the second separator 107, and the diffusion layer 105 is overlapped on the surface 207 a of the second separator 107 to close the grooves 108. A second flow path (not shown) to be a flow path is formed.
[0005]
On the other hand, it is necessary to effectively bring fuel gas into contact with the anode side electrode 102. Therefore, a plurality of grooves (not shown) are provided on the surface 106a of the first separator 106, and the diffusion layer 104 is overlaid on the surface 106a of the first separator 106 to close the groove, thereby forming a fuel gas flow path. One flow path (not shown) is formed.
[0006]
The first separator 106 is provided with a plurality of cooling water passage grooves 109 ... on the back surface 106b of the surface 106a, and the second separator 107 is provided with cooling water passage grooves (not shown) on the back surface 107b of the surface 107a. There are a number of this article.
By superimposing the first and second separators 106 and 107, the cooling water passage grooves 109 are combined to form a cooling water passage (not shown).
[0007]
[Problems to be solved by the invention]
As a method for manufacturing the first and second separators 106 and 107, for example, Japanese Patent Laid-Open No. 2001-126744 “Fuel Cell Separator and Method for Manufacturing the Same” is known.
According to this manufacturing method, heat kneading is performed in a state in which conductive particles are included in a thermoplastic resin, the mixture is extruded, formed into a long sheet with a rolling roll, and the long sheet is cut into a predetermined dimension. Then, after forming a blank material, the first and second separators 106 and 107 can be obtained by stamping molding gas passages and cooling water passage grooves on one or both sides of the blank material.
[0008]
In order to form the first and second flow paths by superimposing the diffusion layers 104 and 105 on the first and second separators 106 and 107, respectively, the surfaces 106a and 107a of the first and second separators 106 and 107, respectively. In addition, it is necessary to overlap the diffusion layers 104 and 105 in close contact.
[0009]
However, it is difficult to overlay the diffusion layers 104 and 105 in close contact with the surfaces 106a and 107a of the first and second separators 106 and 107, and the first and second separator surfaces 106a and 107a and the diffusion layers 104 and 105 are difficult to overlap. There is a possibility that a gap is partially generated between the two.
[0010]
On the other hand, the first separator 106 and the second separator 107 are overlapped to form the cooling water passages on the respective surfaces. Therefore, it is necessary to overlap the first separator 106 and the second separator 107 in close contact with each other.
However, it is difficult to overlap the first separator 106 and the second separator 107 in close contact with each other, and a gap may be partially generated between the first separator 106 and the second separator 107.
[0011]
Therefore, the surfaces 106a and 107a of the first and second separators 106 and 107 and the diffusion layers 104 and 105 can be overlapped with each other, and the first separator 106 and the second separator 107 are in close contact with each other. Therefore, there has been a demand for practical use of a separator for a fuel cell that can be superimposed on the substrate.
[0012]
Moreover, the conventional manufacturing method of the separator for fuel cells is to cut a long sheet into a predetermined size to obtain a blank material, and then form a groove for a gas passage or a groove for a cooling water passage in each blank material. It is.
According to this method for manufacturing a separator for a fuel cell, it is necessary to position each blank material at a normal position when grooves are formed in the blank material.
Therefore, it takes time to position the blank material, which hinders productivity. For this reason, the practical use of the manufacturing method which can shape | mold the separator for fuel cells more efficiently was desired.
[0013]
  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel cell separator that can close the overlapping portion of the fuel cell separator and the diffusion layer, and can further increase the productivity of the fuel cell separator.TIs to provide.
[0014]
[Means for Solving the Problems]
  In order to achieve the above object, claim 1 is a fuel cell separator in which an anode side electrode and a cathode side electrode along an electrolyte membrane are sandwiched from both sides through a diffusion layer.Vinyl acetateThermoplastic resin selected from copolymers and ethylene / ethyl acrylate copolymers14-20% by massAnd carbon particles selected from at least one of ketjen black, graphite, and acetylene black70-83.5% by massWhen, 2.5 to 10% by mass of glass fiber or carbon fiber,Formed with mixed material containing3-20% by mass of the carbon particles is the ketjen black.It is characterized by that.
[0015]
A thermoplastic resin selected from an ethylene / vinyl acetate copolymer and an ethylene / ethyl acrylate copolymer was included in the separator. An ethylene / vinyl acetate copolymer and an ethylene / ethyl acrylate copolymer are particularly excellent in flexibility among thermoplastic resins.
Therefore, by including the thermoplastic resin excellent in flexibility in the separator, the contact surface of the separator that contacts the diffusion layer can be provided with elasticity, and the contact surface should be a portion having excellent sealing properties. Can do.
[0016]
Furthermore, the contact surface of a separator can be changed into the site | part excellent in the sealing property only by making the separator contain the thermoplastic resin selected from the ethylene-vinyl acetate copolymer and the ethylene-ethyl acrylate copolymer. Thereby, the separator excellent in sealing performance can be produced efficiently.
[0017]
On the other hand, carbon particles such as ketjen black, graphite, and acetylene black have electrical conductivity. By including these carbon particles in the separator, the electrical conductivity of the separator can be ensured.
[0018]
  Also,Claim1In,heatPercentage of plastic resinThe14-20% by massIt was.
[0019]
The reason why the ratio of the thermoplastic resin is set to 14 to 20% by mass is as follows. When the content of the thermoplastic resin is less than 14% by mass, the content of the thermoplastic resin is too small and it becomes difficult to ensure the elasticity of the contact surface of the separator, that is, the sealing property.
[0020]
On the other hand, when the content of the thermoplastic resin exceeds 20% by mass, the content of the carbon particles contained in the separator decreases, and it becomes difficult to sufficiently secure the conductivity of the separator.
Therefore, the content of the thermoplastic resin is set to 14 to 20% by mass to ensure the separator's sealing performance and ensure sufficient conductivity.
[0021]
  further,Claim1Is 3 to 20% by mass of the carbon particlesTheKetjen BlackIt was.
[0022]
Ketjen black is a member that is particularly excellent in conductivity as compared with other carbon blacks, and the conductivity of the separator can be increased by including ketjen black.
[0023]
Here, the reason why the ketjen black content is set to 3 to 20% by mass is that when the ketjen black content is less than 3% by mass, the ketjen black content is too small, It becomes difficult to obtain the included effect. For this reason, if the content of ketjen black is less than 3% by mass, the conductivity of the separator may not be sufficiently ensured.
[0024]
On the other hand, when the content of ketjen black exceeds 20% by mass, the content of ketjen black is too large to be kneaded. Although it may be possible to knead by adding a solvent, the use of a solvent may increase the cost.
In addition, even if the solvent can be added and kneaded, the kneaded material containing ketjen black has poor flowability, and it is difficult to obtain a predetermined shape at the time of molding, for example.
Therefore, by setting the content of ketjen black to 3 to 20% by mass, the conductivity of the separator is sufficiently ensured, further kneading is facilitated and moldability is suitably ensured.
[0025]
  in addition,Claim1 is, Mixed materialThe, Thermoplastic treeFat 14-20% by mass, carbon particlesChild 70-83.5% by mass, glass fiber or carbon fiberWei 2. 5-10% by massIt was.
[0026]
By mixing glass fiber or carbon fiber into the mixed material, the rigidity of the separator can be increased.
Here, the reason why the glass fiber or carbon fiber content is set to 2.5 to 10% by mass is that the glass fiber or carbon fiber content is less than 2.5% by mass. It is difficult to increase the rigidity of the first and second separators 20 and 30 because the amount is too small.
[0027]
On the other hand, when the content of glass fiber or carbon fiber exceeds 10% by mass, the content of glass fiber or carbon fiber is too large, and it is difficult to uniformly disperse glass fiber or carbon fiber in the mixed material. Extrusion molding or press molding becomes difficult.
Therefore, the content of glass fiber or carbon fiber is set to 2.5 to 10% by mass to increase the rigidity of the first and second separators 20 and 30, and to obtain a mixed material excellent in moldability. .
[0030]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
  FIG. 1 shows a fuel cell separator according to the present invention.OfIt is a disassembled perspective view which shows a fuel cell.
  As an example, the fuel cell 10 uses a solid polymer electrolyte for the electrolyte membrane 12, the anode side electrode 13 and the cathode side electrode 14 are attached to the electrolyte membrane 12, and the anode side electrode diffusion layer 15 is provided on the anode side electrode 13 side. The cell module 11 is configured by aligning the separator 18 via the cathode side electrode 14 and the separator (fuel cell separator) 18 via the cathode side electrode diffusion layer 16 on the cathode side electrode 14 side. This is a solid polymer fuel cell.
[0031]
The separator 18 includes a first separator 20 and a second separator 30, and the cooling water passage forming surface 20 a of the first separator 20 and the joining surface 30 a of the second separator 30 are joined by a vibration welding method as an example. is there.
[0032]
Thus, by vibration welding the first and second separators 20, 30, the cooling water passage grooves 21... Of the first separator 20 are covered with the second separator 30, and the cooling water passages 22. (Shown in FIG. 4).
The cooling water passages 22... Communicate with cooling water supply holes 23 a and 33 a at the center of the upper ends of the first and second separators 20 and 30 and at the center of the lower ends of the first and second separators 20 and 30. The cooling water discharge holes 23b and 33b communicate with each other.
[0033]
The first separator 20 includes a fuel gas passage groove 24 (shown in FIG. 2) on the fuel gas passage formation surface (contact surface) 20b side, and the anode side electrode diffusion layer 15 is provided on the fuel gas passage formation surface 20b. By overlapping, the fuel gas passage grooves 24 are closed by the anode-side electrode diffusion layer 15 to form fuel gas passages 25 (shown in FIG. 4).
The fuel gas supply holes 26a and 36a on the upper left side of the first and second separators 20 and 30 are communicated with the fuel gas passages 25 ..., and the fuel on the lower right side of the lower ends of the first and second separators 20 and 30 is communicated. The gas discharge holes 26b and 36b are communicated.
[0034]
The second separator 30 includes oxidant gas passage grooves 37 on the oxidant gas passage formation surface (contact surface) 30b side, and the cathode side electrode diffusion layer 16 is overlaid on the oxidant gas passage formation surface 30b. Then, the oxidant gas passage grooves 37 are closed by the cathode side electrode diffusion layer 16 to form oxidant gas passages 38 (shown in FIG. 4).
The oxidant gas passages 38... Communicate with the oxidant gas supply holes 29 a and 39 a on the right side of the upper ends of the first and second separators 20 and 30, and the lower left sides of the first and second separators 20 and 30. The oxidant gas discharge holes 29b and 39b are communicated with each other.
[0035]
As the resin for forming the first and second separators 20 and 30, thermoplastic resins selected from ethylene / vinyl acetate (vinyl acetate) copolymers and ethylene / ethyl acrylate copolymers, ketjen black, graphite, and acetylene are used. A mixed material obtained by mixing carbon particles (carbon material) selected from at least one of black and glass fibers or carbon fibers is applicable.
[0036]
In this mixed material, the ratio of the thermoplastic resin is 14 to 20% by mass, the ratio of the carbon particles is 80 to 86, and 3 to 20% by mass of ketjen black is included among the 80 to 86% by mass of the carbon particles. It is.
The ketjen black is a carbon black having excellent conductivity. For example, the ketjen black manufactured by Ketjen Black International Co., Ltd. (distributor: Mitsubishi Chemical Corporation) is applicable, but is not limited thereto.
[0037]
The ethylene / vinyl acetate (vinyl acetate) copolymer and the ethylene / ethyl acrylate copolymer are flexible resins among the thermoplastic resins. By using this resin, the first and second separators 20, 30 can be a member having excellent flexibility.
Ketjen black, graphite, and acetylene black are materials having excellent electrical conductivity. By using carbon particles selected from at least one of ketjen black, graphite, and acetylene black as the carbon material, the first and second materials are used. The separators 20 and 30 can be members having excellent electrical conductivity.
[0038]
The reason why the ratio of the thermoplastic resin is set to 14 to 20% by mass is as follows. When the content of the thermoplastic resin is less than 14% by mass, the content of the thermoplastic resin is too small and it is difficult to ensure the flexibility of the contact surfaces of the first and second separators 20 and 30, that is, the elasticity.
[0039]
On the other hand, if the content of the thermoplastic resin exceeds 20% by mass, it is difficult to maintain the desired volume resistivity (Ω · cm) because the content of the thermoplastic resin is too large, and the first and second separators 20 , 30 is difficult to ensure sufficiently.
Therefore, the content of the thermoplastic resin is set to 14 to 20% by mass to ensure the elasticity of the first and second separators 20 and 30 and to ensure sufficient conductivity.
[0040]
The reason why the content of carbon particles is set to 80 to 86% by mass is as follows.
When the carbon particle content exceeds 86% by mass, the carbon particle content is too high, and it is difficult to uniformly disperse the carbon particles, which makes extrusion molding and press molding difficult. Therefore, it is preferable to set the carbon particle content to 86% by mass or less.
[0041]
In addition, the volume resistivity (Ω · cm) of the first and second separators 20 and 30 is reduced by securing the content of carbon particles to 70% by mass or more, so that the first and second separators 20 and 30 are reduced. It is possible to sufficiently increase the conductivity. For this reason, it is preferable to ensure the content of carbon particles to 70% by mass or more.
However, since the first and second separators 20 and 30 contain 14 to 20% by mass of thermoplastic resin, in the first embodiment, the content of carbon particles is set to 80% by mass or more. The second separators 20 and 30 have sufficient conductivity.
[0042]
By the way, ketjen black is a carbon particle excellent in conductivity as compared with normal carbon black. For this reason, by using ketjen black, the volume resistivity (Ω · cm) of the first and second separators 20 and 30 can be significantly reduced. The content of this ketjen black was set to 3 to 20% by mass.
[0043]
The reason why the ketjen black content is set to 3 to 20% by mass is as follows.
If the ketjen black content is less than 3% by mass, the ketjen black content is too small and it is difficult to obtain the effect of including the ketjen black. For this reason, if the content of ketjen black is less than 3% by mass, the conductivity of the first and second separators 20 and 30 may not be sufficiently ensured.
[0044]
On the other hand, when the content of ketjen black exceeds 20% by mass, the content of ketjen black is too large to be kneaded. Although it may be possible to knead by adding a solvent, the use of a solvent may increase the cost.
In addition, even if the solvent can be added and kneaded, the kneaded material containing ketjen black has poor flowability, and it is difficult to obtain a predetermined shape at the time of molding, for example.
Therefore, by setting the content of ketjen black to 3 to 20% by mass, the conductivity of the separator is sufficiently ensured, further kneading is facilitated and moldability is suitably ensured.
[0045]
2 is a cross-sectional view taken along line AA in FIG.
The first separator 20 is a member formed in a substantially rectangular shape as shown in FIG. 1, and includes a plurality of cooling water passage grooves 21 on the cooling water passage forming surface 20a, and a fuel gas passage forming surface (contact surface). ) 20b is provided with a large number of fuel gas passage grooves 24.
[0046]
The first separator 20 was made to contain a thermoplastic resin selected from an ethylene / vinyl acetate copolymer and an ethylene / ethyl acrylate copolymer. An ethylene / vinyl acetate copolymer and an ethylene / ethyl acrylate copolymer are particularly excellent in flexibility among thermoplastic resins.
Therefore, by including the thermoplastic resin having excellent flexibility in the first separator 20, the fuel gas passage forming surface 20b can be provided with elasticity.
[0047]
Furthermore, the fuel gas passage forming surface 20b is changed to a portion having excellent sealing properties simply by including in the first separator 20 a thermoplastic resin selected from an ethylene / vinyl acetate copolymer and an ethylene / ethyl acrylate copolymer. be able to. Thereby, the 1st separator 20 excellent in the sealing performance can be produced efficiently.
[0048]
3 is a cross-sectional view taken along line BB in FIG.
The second separator 30 is a member formed in a substantially rectangular shape as shown in FIG. 1, and has a joining surface 30a formed flat, and an oxidant gas passage groove 37 · is formed on an oxidant gas passage formation surface (contact surface) 30b.・ Many provisions of this article.
[0049]
The second separator 30 was made to contain a thermoplastic resin selected from an ethylene / vinyl acetate copolymer and an ethylene / ethyl acrylate copolymer. An ethylene / vinyl acetate copolymer and an ethylene / ethyl acrylate copolymer are particularly excellent in flexibility among thermoplastic resins.
Therefore, the oxidant gas passage forming surface 30b can be provided with elasticity by including the thermoplastic resin having excellent flexibility in the second separator 30.
[0050]
Furthermore, the oxidant gas passage forming surface 30b can be made a portion having excellent sealing properties by simply including the second separator 30 with a thermoplastic resin selected from an ethylene / vinyl acetate copolymer and an ethylene / ethyl acrylate copolymer. Can be changed. Thereby, the 2nd separator 30 excellent in the sealing performance can be produced efficiently.
[0051]
FIG. 4 is a cross-sectional view showing a fuel cell separator according to the present invention.
The separator 18 applies frictional force to the first and second separators 20 and 30 after the first and second separators 20 and 30 are overlapped, and vibrates one of the first and second separators 20 and 30 to generate frictional heat. Is generated by vibration welding the cooling water passage forming surface 20 a of the first separator 20 and the joining surface 30 a of the second separator 30, and the cooling water passage groove 21 of the first separator 20 is formed by the second separator 30. The cooling water passage 22 is formed by closing.
[0052]
By aligning the anode side electrode diffusion layer 15 with the fuel gas passage forming surface 20 b, the fuel gas passage grooves 25... And the anode side electrode diffusion layer 15 form fuel gas passages 25.
Here, by including the thermoplastic resin having excellent flexibility in the second separator 30, the fuel gas passage forming surface 20b can be provided with elasticity, and the fuel gas passage forming surface 20b has excellent sealing properties. Can be a site.
[0053]
For this reason, the overlapping part of the fuel gas passage forming surface 20b and the anode-side electrode diffusion layer 15 can be kept dense. Therefore, it is not necessary to apply a sealing material between the fuel gas passage forming surface 20 b and the anode side electrode diffusion layer 15.
Therefore, it is possible to reduce the number of parts and save the trouble of applying the sealing material, and further to suppress the contact resistance between the fuel gas passage forming surface 20b and the anode side electrode diffusion layer 15 and increase the output of the fuel cell. Can do.
[0054]
Further, by combining the cathode side electrode diffusion layer 16 with the oxidant gas passage formation surface 30b, the oxidant gas passages 38 ... are formed by the oxidant gas passage grooves 37 ... and the cathode side electrode diffusion layer 16. .
Here, the second separator 30 includes a flexible thermoplastic resin so that the oxidant gas passage forming surface 30b can have elasticity, and the oxidant gas passage forming surface 30b has a sealing property. It can be an excellent site.
[0055]
For this reason, the overlapping portion of the oxidizing gas passage forming surface 30b and the cathode-side electrode diffusion layer 16 can be kept dense. Therefore, it is not necessary to apply a sealing material between the oxidant gas passage forming surface 30b and the cathode side electrode diffusion layer 16.
Therefore, it is possible to reduce the number of parts and to save the trouble of applying the sealing material, and further to suppress the contact resistance between the oxidant gas passage forming surface 30b and the cathode side electrode diffusion layer 16 and increase the output of the fuel cell. be able to.
[0056]
Next, an example in which the first separator 20 is formed by the method for manufacturing a fuel cell separator according to the present invention will be described with reference to FIGS.
FIG. 5 is a flowchart showing an outline of a method for manufacturing a fuel cell separator according to the present invention, where STxx indicates a step number.
ST10: A mixture is obtained by kneading the thermoplastic resin and the conductive material. ST11: A belt-like sheet is formed by extruding the kneaded mixed material.
[0057]
ST12: The cooling water passage groove is press-formed on one surface of the belt-like sheet, that is, the surface corresponding to the cooling water passage forming surface, and the other surface of the belt-like sheet, that is, the fuel gas passage forming surface. A separator material is obtained by press molding a groove for a fuel gas passage on the surface.
[0058]
ST13: A first separator is obtained by cutting the separator material into predetermined dimensions.
Hereinafter, steps ST10 to ST13 of the method for manufacturing a fuel cell separator according to the present invention will be described in detail with reference to FIGS.
[0059]
6 (a) and 6 (b) are first explanatory views of a method for manufacturing a fuel cell separator according to the present invention, wherein (a) shows ST10 and (b) shows the first half of ST11.
In (a), first, a thermoplastic resin 46 selected from an ethylene / vinyl acetate copolymer, an ethylene / ethyl acrylate copolymer, and a linear low density polyethylene is prepared.
[0060]
Next, a conductive material 45 selected from at least one of carbon particles of graphite, ketjen black, and acetylene black is prepared.
The prepared thermoplastic resin 46 and conductive material 45 are put into a container 48 of a kneading apparatus 47 as shown by an arrow. The introduced thermoplastic resin 46 and conductive material 45 are kneaded in a container 48 by rotating a kneading blade (or screw) 49 as shown by an arrow.
[0061]
In (b), the kneaded mixed material 50 is put into the hopper 52 of the first extrusion molding device 51, and the fed mixed material 50 is extrusion molded by the first extrusion molding device 51. By passing the extruded molding material 53 through the water tank 54, the molding material 53 is cooled by the water 55 in the water tank 54.
The cooled molding material 53 is cut into a predetermined length by the cutter 57 of the cutter device 56, and the cut pellets 58.
[0062]
FIG. 7 is a second explanatory view of the method for producing a fuel cell separator according to the present invention, and shows the latter half of ST11 to ST13.
The pellets 58... Obtained in the previous step are put into the hopper 61 of the second extrusion molding device 60 as shown by the arrow, and the fed pellets 58 are extruded by the second extrusion molding device 60. The extruded material 62 is rolled with a rolling roll 63 to form a belt-like sheet 64.
[0063]
A pressing device 65 is provided on the downstream side of the rolling roll 63, and the pressing device 65 includes upper and lower press dies 66 and 67 above and below a belt-like sheet 64.
The upper press die 66 includes a concavo-convex portion (not shown) on the press surface 66 a facing the other surface 64 b of the belt-like sheet 64. The concavo-convex portions are formed by press-molding the fuel gas passage grooves 24 (shown in FIG. 4) on the other surface 64 b of the belt-like sheet 64.
[0064]
On the other hand, the lower press die 67 includes a concavo-convex portion (not shown) on the press surface 67 a facing the one surface 64 a of the belt-like sheet 64. This uneven part press-molds the cooling water passage groove 21 (shown in FIG. 4) on one surface 64 a of the belt-like sheet 64.
[0065]
The upper and lower press dies 66 and 67 are arranged at the press start position P1, and the upper and lower press dies 66 and 67 press the both surfaces 64a and 64b of the belt-like sheet 64, and the upper and lower press dies 66 and 67 are maintained in this state. Are interlocked as indicated by arrows {circle around (1)} and {circle around (2)} according to the extrusion speed of the belt-like sheet 64.
[0066]
Thus, the cooling water passage grooves 21 are press-formed on one surface 64a of the belt-like sheet 64, that is, the surface corresponding to the cooling water passage forming surface 20a (shown in FIG. 4), and the belt-like sheet 64 is formed. The other side 64b, that is, the surface corresponding to the fuel gas passage forming surface 20b (shown in FIG. 4) is press-molded with the fuel gas passage grooves 24. be able to.
[0067]
When the upper and lower press dies 66 and 67 reach the press release position P2, the upper and lower press dies 66 and 67 are moved away from the belt-like sheet 64 as indicated by arrows (3) and (4). , 67 reach the predetermined position on the release side, and the upper and lower press dies 66, 67 are moved toward the upstream side as indicated by arrows (5), (6).
[0068]
After the upper and lower press dies 66 and 67 reach a predetermined position on the press start side, the upper and lower press dies 66 and 67 are moved to the press start position P1 as indicated by arrows (7) and (8).
By sequentially repeating the steps described above, the cooling water passage grooves 21... And the fuel gas passage grooves 24... Can be respectively press-formed on both surfaces 64 a and 64 b of the belt-like sheet 64.
[0069]
In FIG. 7, an example in which one upper and lower press dies 66 and 67 are provided for easy understanding has been described, but in reality, a plurality of upper and lower press dies 66 and 67 are provided.
By providing a plurality of upper and lower press dies 66 and 67 respectively, the cooling water passage groove 21... And the fuel gas passage groove 24... (Shown in FIG. 4) on both surfaces 64 a and 64 b of the belt-like sheet 64. Can be continuously press-molded.
[0070]
The upper and lower press dies 66 and 67 are provided with portions for forming the fuel gas supply hole 26a and the fuel gas discharge hole 26b shown in FIG. Further, the upper and lower press dies 66 and 67 are provided with portions for forming the oxidant gas supply hole 29a and the oxidant gas discharge hole 29b shown in FIG.
Further, the upper and lower press dies 66 and 67 are provided with portions for forming the cooling water supply hole 23a and the cooling water discharge hole 23b shown in FIG.
[0071]
Therefore, the cooling water passage groove 21... And the fuel gas passage groove 24... Are continuously press-molded on both surfaces 64 a and 64 b of the belt-like sheet 64 by the upper and lower press dies 66 and 67, respectively. The cooling water supply hole 23a and the gas supply holes 26a and 29a, the cooling water discharge hole 23b, and the gas discharge holes 26b and 29b shown in FIG.
[0072]
On the downstream side of the press device 65, a cutter device 73 is provided above the separator material 68 obtained in the previous step.
By lowering the cutter 71 of the cutter device 70 as shown by the arrow (9), the separator material 68 is cut to a predetermined size to obtain the first separators 20. Thereby, the manufacturing process of the 1st separator 20 is completed.
[0073]
As described above, according to the method for manufacturing a fuel cell separator according to the present invention, the coolant 50 is formed on the both surfaces 64a and 64b of the mixed material 50 as the belt-like sheet 64 and the fuel gas. After each of the passage grooves 24... Is pressed, the sheet 64 is cut into a predetermined shape to obtain the first separator 20.
[0074]
Thus, the cooling water passage grooves 21... And the fuel gas passage grooves 24... And the fuel gas passage grooves 21. 24... Can be formed continuously and efficiently, so that the productivity of the first separator 20 can be increased.
[0075]
Although the example which shape | molds the 1st separator 20 was demonstrated in FIGS. 5-7, it is possible to manufacture the 2nd separator 30 by the method similar to the manufacturing method of the 1st separator 20. FIG.
However, unlike the first separator 20, the second separator 30 does not include the cooling water passage grooves 21, but includes a flat joining surface 30 a. For this reason, the lower press die 67 shown in FIG. 7 has unevenness that press-molds the cooling water passage grooves 21 on one surface of the belt-like sheet 64 on the surface facing the one surface of the belt-like sheet 64. It is not necessary to provide a part.
[0076]
Next, a second embodiment will be described.
In the first embodiment, the example in which the ratio of the thermoplastic resin included in the first and second separators 20 and 30 is 14 to 20% by mass and the ratio of the carbon particles is 80 to 86% by mass has been described. The ratio of the thermoplastic resin contained in the second separators 20 and 30 is 14 to 20% by mass, the ratio of carbon particles is 70 to 83.5% by mass, and the ratio of glass fiber or carbon fiber is 2.5 to 10% by mass. It is also possible.
[0077]
The first and second separators 20 and 30 of the second embodiment can increase the rigidity of the first and second separators 20 and 30 by mixing glass fibers or carbon fibers with a mixed material.
Here, the reason for setting the glass fiber or carbon fiber content to 2.5 to 10% by mass is as follows.
When the glass fiber or carbon fiber content is less than 2.5% by mass, it is difficult to increase the rigidity of the first and second separators 20 and 30 because the glass fiber or carbon fiber content is too small.
[0078]
On the other hand, when the content of glass fiber or carbon fiber exceeds 10% by mass, the content of glass fiber or carbon fiber is too large, and it is difficult to uniformly disperse glass fiber or carbon fiber in the mixed material. Extrusion molding or press molding becomes difficult.
Therefore, the content of glass fiber or carbon fiber is set to 2.5 to 10% by mass to increase the rigidity of the first and second separators 20 and 30, and to obtain a mixed material excellent in moldability. .
[0079]
The reason why the content of the carbon particles is set to 70 to 83.5% by mass is as follows.
When the carbon particle content is less than 70% by mass, it is difficult to reduce the volume resistivity (Ω · cm) of the first and second separators 20 and 30 because the carbon particle content is too small. It is difficult to ensure sufficient conductivity of the second separators 20 and 30.
[0080]
On the other hand, as described above, when the content of carbon particles exceeds 86% by mass, it is difficult to uniformly disperse the carbon particles because the carbon particle content is too high, and extrusion molding and press molding become difficult. Therefore, it is preferable to set the carbon particle content to 86% by mass or less.
However, since the first and second separators 20 and 30 contain 14 to 20% by mass of thermoplastic resin and 2.5 to 10% by mass of glass fiber or carbon fiber, in the second embodiment, The carbon particle content was set to 83.5% by mass or less, and the carbon particles were uniformly dispersed so that extrusion molding and press molding could be suitably performed.
Thus, by setting the content of carbon particles to 70 to 83.5% by mass, it is possible to reduce the volume resistivity (Ω · cm) and obtain a mixed material excellent in moldability.
[0081]
According to the first and second separators 20 and 30 of the second embodiment, the same effects as those of the first embodiment can be obtained. In addition, by mixing glass fibers or carbon fibers, the first and second separators can be obtained. The rigidity of the separators 20 and 30 can be increased.
[0082]
In the above-described embodiment, the solid polymer fuel cell 10 using the solid polymer electrolyte as the electrolyte membrane 12 has been described. However, the present invention is not limited to this, and can be applied to other fuel cells.
[0083]
Moreover, although the said embodiment demonstrated the example which shape | molded the 1st, 2nd separator 20 and 40 continuously by extrusion molding or press molding, it is not restricted to this, A hot press method, an injection molding method, and transfer molding It is also possible to mold by other manufacturing methods such as the method.
The transfer molding method is a method in which a molding material is put into a pot part separate from the cavity for one shot, and the molten material is transferred to the cavity by a plunger and molded.
[0084]
【The invention's effect】
The present invention exhibits the following effects by the above configuration.
In the first aspect, a thermoplastic resin selected from an ethylene / vinyl acetate copolymer and an ethylene / ethyl acrylate copolymer is included in the separator. An ethylene / vinyl acetate copolymer and an ethylene / ethyl acrylate copolymer are particularly excellent in flexibility among thermoplastic resins.
[0085]
Therefore, by including the thermoplastic resin excellent in flexibility in the separator, the contact surface of the separator that contacts the diffusion layer can be provided with elasticity, and the contact surface should be a portion having excellent sealing properties. Can do.
For this reason, the overlapping portion of the contact surface of the separator and the diffusion layer can be kept dense. Therefore, it is not necessary to apply a sealing material between the contact surface of the separator and the diffusion layer.
[0086]
Furthermore, the contact surface of a separator can be changed into the site | part excellent in the sealing property only by making the separator contain the thermoplastic resin selected from the ethylene-vinyl acetate copolymer and the ethylene-ethyl acrylate copolymer. Thereby, the separator excellent in sealing performance can be produced efficiently.
[0087]
On the other hand, carbon particles such as ketjen black, graphite, and acetylene black have conductivity, and the conductivity of the separator can be secured by including these carbon particles in the separator.
[0088]
  Also,Claim1Is the ratio of the thermoplastic resin of the mixture to 14-20 mass%Whendid. Thus, by setting the content of the thermoplastic resin to 14% by mass or more, the content of the thermoplastic resin can be ensured and the elasticity of the contact surface of the separator, that is, the sealing property can be ensured.
  On the other hand, when the content of the thermoplastic resin is 20% by mass or less, the content of the carbon particles contained in the separator can be suitably maintained, and the conductivity of the separator can be sufficiently ensured.
[0089]
  further,Claim1Used 3 to 20% by mass of carbon particles as ketjen black. Ketjen black is a member that is particularly excellent in conductivity as compared with other carbon blacks, and the conductivity of the separator can be efficiently increased by including ketjen black.
[0090]
Thus, by setting the ketjen black content to 3% by mass or more, the ketjen black content can be secured to some extent, and the effect of including the ketjen black can be obtained. Sufficient electrical conductivity can be ensured.
On the other hand, by setting the ketjen black content to 20% by mass or less, sufficient conductivity of the separator is ensured, further kneading is facilitated and moldability is suitably secured.
[0091]
  in addition,Claim1The ratio of the thermoplastic resin is 14 to 20% by mass, the ratio of carbon particles is 70 to 83.5% by mass, and the ratio of glass fiber or carbon fiber is 2.5 to 10% by mass. By mixing glass fiber or carbon fiber into the mixed material, the rigidity of the separator can be increased.
[0092]
Thus, by setting the glass fiber or carbon fiber content to 2.5 mass% or more, the glass fiber or carbon fiber content can be ensured and the rigidity of the separator can be increased.
On the other hand, by making the content of glass fiber or carbon fiber 20% by mass or less, the content of glass fiber or carbon fiber can be suitably maintained, and the glass fiber or carbon fiber can be uniformly dispersed, and the moldability is improved. Get an excellent separator.
Thus, the productivity of a separator can be improved by setting it as the separator excellent in the moldability.
[Brief description of the drawings]
FIG. 1 shows a fuel cell separator according to the present invention.OfExploded perspective view showing a fuel cell
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a sectional view taken along line BB in FIG.
FIG. 4 is a cross-sectional view showing a fuel cell separator according to the present invention.
FIG. 5 is a flowchart showing a method for manufacturing a fuel cell separator according to the present invention.
FIG. 6 is a first explanatory view of a method for producing a fuel cell separator according to the present invention.
FIG. 7 is a second explanatory diagram of a method for manufacturing a fuel cell separator according to the present invention.
FIG. 8 is an exploded perspective view showing a conventional fuel cell.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 12 ... Electrolyte membrane, 13 ... Anode side electrode, 14 ... Cathode side electrode, 15 ... Anode side electrode diffusion layer (diffusion layer), 16 ... Cathode side electrode diffusion layer (diffusion layer), 18 ... Separator ( Fuel cell separator), 20 ... first separator, 20b ... fuel gas passage formation surface (contact surface), 24 ... fuel gas passage groove, 30 ... second separator, 30b ... oxidant gas passage formation surface (contact surface) 37 ... Oxidant gas passage groove, 45 ... conductive material, 46 ... thermoplastic resin, 50 ... mixed material, 68 ... separator material.

Claims (1)

In the fuel cell separator that sandwiches the anode side electrode and the cathode side electrode along the electrolyte membrane from both sides through the diffusion layer,
This fuel cell separator is composed of 14 to 20% by mass of a thermoplastic resin selected from an ethylene / vinyl acetate copolymer and an ethylene / ethyl acrylate copolymer,
70-83.5% by mass of carbon particles selected from at least one of ketjen black, graphite, and acetylene black ;
2.5 to 10% by mass of glass fiber or carbon fiber,
Forming a mixed material containing,
3 to 20% by mass of the carbon particles is the ketjen black . A fuel cell separator.

Images