JP3682924B2 - Manufacturing method of separator for fuel cell with seal and separator for fuel cell with seal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method for producing a fuel cell separator with a seal and a fuel cell separator with a seal, and more specifically, the seals on both sides of a fuel cell separator are efficiently and high without deforming the fuel cell separator during production. The present invention relates to a method for manufacturing a sealed fuel cell separator that can be provided with high accuracy, and a sealed fuel cell separator.
[0002]
[Prior art]
In recent years, solid polymer fuel cells have attracted attention as power sources for electric vehicles. A polymer electrolyte fuel cell (PEFC) can generate electric power even at room temperature, and is being put into practical use for various applications.
[0003]
In general, a fuel cell system is configured such that a cathode electrode is partitioned on one side and an anode electrode is partitioned on the other side with a solid polymer electrolyte membrane interposed therebetween, and oxygen in the air supplied to the cathode electrode and the anode This system drives an external load with electric power generated by an electrochemical reaction with hydrogen supplied to an electrode.
[0004]
Such a fuel cell system is provided with a fuel cell stack 100 as shown in FIG. The fuel cell stack 100 is a unitary cell in which a single cell that generates electricity with a single membrane sandwiched is repeatedly stacked in a horizontal direction such that the electrode surface is vertical, and tightened with bolts or the like. is there.
As shown in FIG. 4B, the single cell is composed of a polymer electrolyte membrane M, electrode catalyst layers C and C, gas diffusion layers D and D, separators SA and SH, and the like. A structure in which the electrode catalyst layer C and the gas diffusion layer D are provided on one surface side of the polymer electrolyte membrane M and the electrode catalyst layer C and the gas diffusion layer D are provided on the other surface side may be referred to as a membrane electrode assembly MEA. Moreover, code | symbol RS of FIG.4 (b) is a rubber seal material.
[0005]
Among these constituent members, separators SA and SH are used for providing a connection (stacking function) between cells to obtain a required voltage by stacking a plurality of single cells. Functionality is also required.
(1) A function of securing a supply passage for supplying hydrogen and air to the cells in the fuel cell stack 100.
(2) A function of securing a coolant supply passage for cooling the fuel cell stack 100.
(3) A function to collect and take out current (electrons).
[0006]
Such separators SA and SH, when formed as a fuel cell stack, are stacked as described above (see FIG. 4A), but the separator SA in a single cell as one constituent unit. And separator SH are required to have airtightness and liquid-tightness so that hydrogen, air and water do not leak out of the system. Therefore, in order to prevent a ground fault to the outside of the fuel cell stack 100 due to water or condensation water on the fuel cell stack 100, a waterproof structure of the stack container is adopted.
Specifically, various fluids (anode gas, cathode gas, refrigerant) are formed by sandwiching a rubber seal material (fluorine-based, EPDM, etc.) separately formed between the separator SA and the separator SH. It functioned as a seal for a fluid, a passage for various fluids, or a support for the purpose of holding a load (function as a packing material or a cushion material). Here, Patent Document 1 discloses that a seal is integrally formed on both the front and back surfaces of the separators SA and SH.
[0007]
[Patent Document 1]
JP-A-11-129396
In this metal separator according to Patent Document 1, a silicone resin layer having a thickness of 0.05 mm to 1.0 mm and a hardness (JISK6301 spring type hardness test A type) of 40 to 70 is formed by injection molding on at least one surface of a thin metal plate. It is formed by. According to this method, the number of assembling steps can be reduced, and forgetting to attach or defective assembly can be prevented.
[0009]
Further, in the fuel cell stack 100 using the metallic separators SA and SH, there is a possibility that a liquid junction between the cells may occur in the communication hole 110 due to the refrigerant, reaction product gas, condensed water, etc. There is concern about the electrical corrosion of SH.
As a countermeasure, a two-color molding method in which the outer periphery of the communication hole 110 is resin-molded and then sealed with a thermoplastic elastomer or the like is also conceivable.
[0010]
[Problems to be solved by the invention]
However, according to the injection molding method, when a rubber material is to be molded on the front and back of a thin metal plate separator as a fuel cell cushioning material, packing material spacer, and gas leak prevention sealing material, the pressure of the separator during the molding Significant deformation becomes a problem.
Further, in the injection molding method, the material that can be used as the seal is limited to the silicone resin layer, and it cannot be applied when other rubber components are used as the base material.
On the other hand, when two-color molding is performed, the assembly process increases, so that the cost is a problem.
Therefore, the present invention can be applied to various rubber components without deformation of the separator at the time of molding, and a method for manufacturing a separator for a fuel cell with a seal that realizes an insulating structure of a stack body in order to improve waterproof performance, and with a seal It is an object to provide a fuel cell separator.
[0011]
[Means for Solving the Problems]
The present invention is configured to solve the above-mentioned problems, and the invention according to claim 1 is the manufacture of a fuel cell separator with a seal having a seal on the front and back of at least one end of the fuel cell separator. A temporary molding step of temporarily molding a rubber composition to form a temporary seal; a sandwiching step of inserting the separator into the temporary seal; and the temporary seal and the separator in a vulcanization mold. And a main vulcanization step of main vulcanizing the temporary seal to form a molded product.
[0012]
According to the first aspect of the present invention, since the separator and the seal can be integrally molded by inserting the separator between the temporary molded seals that have been preliminarily molded and have a necessary shape, the fuel cell separator It is possible to efficiently and accurately manufacture a seal from the rubber composition without significantly deforming.
[0013]
Here, the “temporary molding seal” means a sealing material vulcanized by the method according to the present invention and having a desired performance. Further, “temporary molding” refers to a state in which a seal made of a rubber composition can maintain a predetermined shape and can be cured (semi-cured) in a further curable state.
In addition, the molded product obtained in the main vulcanization step can be further subjected to secondary vulcanization.
Secondary vulcanization is a conventional means used in final processing of seals composed of rubber compositions. In the present invention, such conventional means can be used for the purpose of complete vulcanization of the seal and volatilization of impurities.
[0014]
According to a second aspect of the present invention, in the method for manufacturing a separator for a fuel cell with a seal according to the first aspect, the separator with a seal includes a communication hole sealing portion that covers a communication hole inner portion of the separator and the communication hole. An outer peripheral seal portion covering the outer peripheral portion of the separator and the outer peripheral portion of the separator, and the inner wall seal portion and the outer peripheral seal portion are temporarily formed using an insulating rubber composition in the temporary molding step. In the sandwiching step, the separator and the temporarily formed seal are bonded with an insulating primer adhesive.
By configuring in this way, it becomes possible to (1) prevent a liquid junction inside the fuel cell due to refrigerant, reaction product gas, condensed water, etc., and (2) prevent a ground fault due to moisture, condensed water, etc. Further, even when there is a defect in the seal portion, it is possible to manufacture a fuel cell separator with a seal that can ensure insulation with an adhesive having an insulating effect.
[0015]
A separator for a fuel cell with a seal having a structure manufactured by such a manufacturing method is novel. Accordingly, the invention described in claim 3 is a fuel cell separator with a seal manufactured by the method for manufacturing a fuel cell separator with a seal according to claim 1 or 2, wherein at least one of the fuel cell separators is provided. that of the seal possess the front and rear end, and has an outer periphery sealing portion that covers the outer portion of the communication hole seal portion and the communication hole to the outer portion of the separator which covers the communication hole interior portion of the separator A separator for a fuel cell with a seal characterized by the following.
By configuring in this way, it becomes possible to (1) prevent a liquid junction inside the fuel cell due to refrigerant, reaction product gas, condensed water, etc., and (2) prevent a ground fault due to moisture, condensed water, etc. It becomes possible.
According to a fourth aspect of the present invention, in the separator with a seal according to the third aspect, the separator and the seal portion are further bonded with an insulating primer adhesive.
By configuring in this way, it becomes possible to (1) prevent a liquid junction inside the fuel cell due to refrigerant, reaction product gas, condensed water, etc., and (2) prevent a ground fault due to moisture, condensed water, etc. In addition, even when there is a defect in the seal portion, it is possible to ensure insulation by an adhesive having an insulating effect.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
In the drawings to be referred to, FIG. 1 is a cross-sectional view of a single cell using a sealed fuel cell separator according to this embodiment.
[0017]
As shown in FIG. 1, the unit cell 1 includes a separator 10 for a fuel cell with a seal according to this embodiment so as to sandwich the polymer electrolyte membrane M, the electrode catalyst layers C and C, and the gas diffusion layers D and D. 10 is arranged.
The fuel cell separator 10 with a seal is formed by integrally molding a plate-shaped separator 11 and seals 12 and 12 disposed on both sides of the separator 11.
[0018]
Separator 11 is used in a fuel cell stack formed by stacking single cells 1 to provide a connection (stacking function) between cells to obtain a required voltage by stacking a plurality of single cells 1. Is.
[0019]
The material of the separator 11 is, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, a thin metal plate subjected to anticorrosion surface treatment, or a carbon-based material in which synthetic graphite, graphite, and a resin are mixed. Although used suitably, it is not specifically limited. Moreover, although the thickness of the separator 11 is not specifically limited, In this embodiment, about 0.05-0.3 mm is assumed.
[0020]
The seal 12 is formed from a rubber composition. In the present embodiment, the seal 12 covers a part of the front and back of the both ends of the separator 11 thinly, and has a shape that is convex on a part of the front and back surfaces of the thinly covered part. The thickness of the thinly covered portion with respect to the surface is about 0.05 to 0.3 mm, and the convex portion is about 1 mm high.
The composition used in the present invention is a composition for forming a sealing material by vulcanization, and is generally composed mainly of a rubber component, a vulcanizing agent, and a vulcanization accelerator, and conventionally used as desired. Various known additives can be added.
The rubber component used in the present invention is not limited, but for example, nitrile rubber, silicone rubber, fluorine rubber, acrylic rubber, styrene butadiene rubber, ethylene propylene rubber, tetrafluoroethylene resin, acrylonitrile butadiene rubber, Isoprene rubber, butadiene rubber, butyl rubber, chloropyrene rubber, ethylene propylene diene (EPDM) rubber, urethane rubber, chlorosulfonated polyethylene rubber, chlorinated polyethylene rubber, various synthetic rubbers such as epichlorohydrin rubber and natural rubber (NBR), or these A blend is mentioned.
These rubber components can be appropriately selected according to the properties of the seal to be formed.
[0021]
The vulcanizing agent and vulcanization accelerator and the amount added thereof in the composition of the present invention are appropriately selected from compounds known in the art. For example, examples of the vulcanizing agent include sulfur, peroxide, polyamine, thiuram-disulfide, and examples of the vulcanizing accelerator include guanidines, thioureas, thiazoles, dithiocarbamates, and the like.
Further, as other components, a colorant such as titanium oxide, petiole, ultramarine blue, carbon black and the like may be added.
A composition composed of such components generally becomes a viscous fluid when heated.
[0022]
A manufacturing method in which the separator 11 and the seal 12 described above are integrally formed to form a fuel cell separator 10 with a seal will be described below.
FIG. 2 is a diagram for explaining a manufacturing process of a separator for a fuel cell with a seal, in which (a) is a diagram in which a rubber composition is temporarily molded to form a temporary molded seal, and (b) is a diagram between temporary molded seals. The figure which inserts a separator in (c), the figure which hold | maintains a seal | sticker and a separator, and the figure which carries out the main vulcanization | cure of a temporary molding seal, (d) is a figure of a molded article.
[0023]
First, as a first step, the rubber composition 12a is temporarily molded (temporary molding step; see FIG. 2 (a)).
The temporary molding step is a step aimed at molding the rubber composition 12a into a temporary molded seal 12b having a predetermined shape, and the final seal 12 is formed by complete vulcanization as in the prior art. Absent.
Since the temporary molding seal 12b is formed on the front and back sides of the separator 11, the one formed on the front surface and the one formed on the back surface are separately molded.
In the present embodiment, the rubber composition 12a is molded by a conventionally known rubber component molding method, for example, transfer molding under the condition that the rubber composition 12a has a predetermined shape according to the components in the selected rubber composition 12a. The composition 12a is formed into a temporary seal 12b.
For example, in the rubber composition 12a, the selected rubber component is ethylene propylene rubber (EPDM), and when this is formed by transfer molding, it is molded at a temperature of about 60 to 170 ° C. for about 2 minutes. In this way, the rubber composition 12a becomes a temporary seal 12b having a predetermined rubber shape.
[0024]
As a second step, the separator 11 is inserted into the temporary seal 12b (nipping step; see FIG. 2 (b)).
In the sandwiching process, the separator 11 is placed on the front surface (or back surface) temporary molding seal 12b molded in the temporary molding step so as to cover the back surface (or front surface) temporary molding seal 12b from above. set.
In this insert, in the next step, a conventionally known adhesive may be applied to the temporary seal 12b or the separator 11 or both for the purpose of preventing the positional deviation of the seal formed on the separator.
[0025]
As a third step, the temporary molding seal 12b is fully vulcanized to form a seal 12 having a desired elasticity (this vulcanization step, see FIG. 2 (c)).
In the main vulcanization step in the present embodiment, the temporary vulcanization of the temporary molding seal 12b is performed while holding the temporary molding seal 12b and the separator 11 in the vulcanization mold.
For example, when the rubber component is the same ethylene propylene rubber (EPDM) as described above and is molded by transfer molding, the temporary molding seal 12b with the separator 11 inserted is pressurized (for example, 7.8-14. 7 MPa), and vulcanize at a temperature of about 150 to 180 ° C. until vulcanization is completed. By this vulcanization in this way, seals 12 having desired properties can be formed on the front and back of the separator.
[0026]
As a fourth step, the sealed fuel cell separator 10 (see FIG. 2D), which is a molded product obtained in the main vulcanization step, may be further subjected to secondary vulcanization (secondary vulcanization step).
The secondary vulcanization step is not necessarily a necessary step in the present invention, and can be appropriately performed as desired.
When the secondary vulcanization process is performed, the vulcanization is not performed until the seal 12 having desired properties is obtained in the above-described main vulcanization process, and a seal is formed on the front and back of the separator 11 (temporary molding seal 12b and seal). Vulcanization is performed for about 12). Next, in the secondary vulcanization step, seals 12 having a desired final shape are formed on the front and back of the separator 11 (for example, vulcanization is performed in an oven at a temperature of about 150 to 180 ° C. until vulcanization is completed. .)
[0027]
According to the above, the following effects can be obtained in the present embodiment.
Since the separator 11 and the seal 12 can be integrally formed by inserting the separator 11 between the temporarily formed seals 12b having the necessary shape, the rubber can be used without greatly deforming the separator 11. The seal 12 can be efficiently and accurately manufactured from the composition 12a.
[0028]
By including the secondary vulcanization step, there is an advantage in that the time in the temporary molding step can be shortened, the vulcanization mold can be effectively used in time, and mass production is facilitated.
Further, by including the secondary vulcanization step, the seal 12 can be completely vulcanized and the impurities can be volatilized.
[0029]
Furthermore, since it is possible to form the rubber composition 12a, which has been difficult to mold with the prior art, into a complex shape, the seal 12 is molded into an optimal shape that can function as a cushioning material and a sealing material. It is also possible to do.
[0030]
As mentioned above, although embodiment of this invention was described, this invention is not limited to these embodiment, A various change is possible. For example, in the present embodiment, the seal 12 is formed at both ends of the separator 11, but the present invention is not limited to this, and may be formed only at one end.
Further, in this embodiment, the seal 12 is formed only at the end of the separator 11, but the present invention can also be applied to the case where a seal is formed in other portions.
Furthermore, for example, the present invention can be applied to the manufacture of a general metal plate with a seal such as a part of an electronic product. Needless to say, the shape, thickness, height, etc. of the seal or separator can be appropriately changed.
[0031]
Next, another embodiment of the present invention will be described with reference to FIG.
FIG. 3 is a schematic view showing a state in which separators for fuel cells with a seal according to a specific embodiment of the present invention are stacked.
As shown in FIG. 3A, the separator 20 for a fuel cell with a seal according to this embodiment has outer peripheral seal portions 22a and 22a made of a rubber composition having insulation properties at both ends of the separator 21 and insulation properties. It has the communicating hole seal parts 22b and 22b produced with the rubber composition. Each outer peripheral seal portion 22 a is an insulating rubber seal formed from the communication hole 23 on the end portion side (outer side) of the separator 21 to the outermost end portion of the separator. On the other hand, each communication hole seal portion 22b is an insulating rubber seal that covers an inner portion of the communication hole.
The thickness of these seal portions is not particularly limited as long as the object and effects of the present invention are achieved. However, in consideration of rubber insulation, moldability, and assembly of the fuel cell stack, 0.05 to 0.4 mm. It is preferable that it is the range of these.
[0032]
With this configuration, insulating seal portions (22a, 22b) are formed on both sides of the communication hole of the separator 21, and fuel such as refrigerant, reaction product water, dew condensation water, etc. as indicated by an arrow X in FIG. It is possible to prevent liquid junction inside the battery.
Also, as shown in FIG. 3, when the sealed fuel cell separators 20 and 20 'according to the specific embodiment of the present invention are arranged in an overlapping manner, the outer peripheral seal portion 22a (lower side) of the sealed fuel cell separator 20 is arranged. Side) and the outer peripheral seal portion 22a ′ (upper side) of the fuel cell separator 20 ′ with seal are in close contact with each other. Therefore, it is possible to prevent a ground fault due to a refrigerant, water, condensed water and the like as indicated by an arrow Y in FIG.
[0033]
It should be noted that the separator 21 and each seal portion are bonded to each other by an insulating insulating primer adhesive (not shown) even if the rubber coating has a defect, or when the seal part is damaged due to fatigue. Even if it exists, this insulating primer adhesive can ensure insulation.
[0034]
Such a separator 20 for a fuel cell with a seal according to the present invention shown in FIG. 3 can be manufactured by the manufacturing process shown in FIG.
That is, a highly insulating material is selected as the rubber composition, a temporary molding step is performed using a vulcanization mold for forming the communication hole seal portion and the outer peripheral seal portion, and then in the sandwiching step, a separator, By applying an insulating primer adhesive to each seal part or both, it is possible to manufacture the fuel cell separator 20 with a seal of the present invention shown in FIG. 3 by the same method.
[0035]
【The invention's effect】
According to the first aspect of the present invention, since the separator and the seal can be integrally molded by inserting the separator between the temporary molded seals that have been preliminarily molded and have a necessary shape, the fuel cell separator It is possible to efficiently and accurately manufacture a seal from the rubber composition without significantly deforming.
According to the second aspect of the present invention, (1) it is possible to prevent a liquid junction inside the fuel cell due to the refrigerant, reaction product gas, condensed water, etc., and (2) a ground fault due to water, condensed water, etc. In addition, it is possible to manufacture a separator for a fuel cell with a seal that can ensure insulation by an adhesive having an insulating effect even when there is a defect in the seal portion.
According to the third and fourth aspects of the invention, (1) it is possible to prevent a liquid junction inside the fuel cell due to the refrigerant, reaction product gas, condensed water, and the like, and (2) wetted water and condensed water. It is possible to prevent a ground fault due to, for example, and (3) it is possible to ensure insulation by an adhesive having an insulating effect even when the seal portion is defective.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a single cell using a sealed fuel cell separator according to an embodiment.
2A and 2B are diagrams for explaining a manufacturing process of a separator for a fuel cell with a seal, wherein FIG. 2A is a diagram in which a rubber composition is temporarily molded to form a temporary molded seal, and FIG. 2B is a diagram between temporary molded seals. The figure which inserts a separator in (c), the figure which hold | maintains a seal | sticker and a separator, and the figure which carries out the main vulcanization | cure of a temporary molding seal, (d) is a figure of a molded article.
FIG. 3 is a schematic view showing a state in which separators for a fuel cell with a seal according to a specific embodiment of the present invention are stacked.
4A is a perspective view showing an external appearance of a conventional fuel cell stack, and FIG. 4B is an enlarged view of the configuration of a single cell in FIG. 4A.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Single cell 10 Fuel cell separator with a seal 11 Separator 12 Seal 12a Rubber composition 12b Temporary molding seal

Claims (4)

A method for producing a fuel cell separator with a seal having a seal on the front and back of at least one end of the fuel cell separator,
Temporary molding step of temporarily molding the rubber composition to form a temporary seal;
A sandwiching step of inserting the separator into the temporary seal;
A main vulcanization step in which the temporary molding seal and the separator are held in a vulcanization mold, and the temporary molding seal is fully vulcanized to form a molded product;
The manufacturing method of the separator for fuel cells with a seal characterized by including these. The separator with a seal has a communication hole seal part that covers the communication hole inner part of the separator and an outer peripheral part seal part that covers the outer part of the separator from the outer part of the communication hole,
Temporarily forming the inner wall surface seal portion and the outer peripheral portion seal portion using a rubber composition having insulating properties in the temporary molding step,
2. The method for manufacturing a separator for a fuel cell with a seal according to claim 1, wherein in the sandwiching step, the separator and the temporary molded seal are bonded with an insulating primer adhesive. 3. A seal with a fuel cell separator manufactured by the manufacturing method of the seal with a fuel cell separator according to claim 1 or claim 2, the seal possess on both sides of at least one end of the fuel cell separator A separator for a fuel cell with a seal, comprising: a communication hole seal portion that covers an inner portion of the communication hole of the separator; and an outer periphery seal portion that covers the outer portion of the separator from the outer portion of the communication hole. . The separator for a fuel cell with a seal according to claim 3, wherein the separator and the seal portion are bonded to each other with an insulating primer adhesive.

Images