JP2004178977A - Manufacturing method of separator for fuel cell with seal and separator for fuel cell with seal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a separator for a fuel cell with a seal capable of being used for various rubber ingredients without deformation of the separator at molding. <P>SOLUTION: The manufacturing method of a separator for the fuel cell with a seal 10 having seals 12 on a front and a rear surfaces of at least one end part of the separator for the fuel cell includes a temporary molding process (Fig. (a)) to temporarily mold a rubber composition 12a into a temporarily molded seal 12b, an insertion process (Fig. (b)) to insert the separator 11 into the temporarily molded seal 12b, and a proper vulcanization process (Fig. (c)) to properly vulcanizing the temporarily molded seal 12b to make up a molded product (the seal 12). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
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 particularly, to efficiently and highly seal both surfaces of the fuel cell separator without deforming the fuel cell separator during production. The present invention relates to a method for manufacturing a fuel cell separator with a seal that can be provided with high precision, and a fuel cell separator with a seal.
[0002]
[Prior art]
2. Description of the Related Art In recent years, polymer electrolyte fuel cells have attracted attention as power sources for electric vehicles. 2. Description of the Related Art A polymer electrolyte fuel cell (PEFC) can generate power even at ordinary temperature, and is being put to practical use in various applications.
[0003]
In general, a fuel cell system is configured such that a cathode is partitioned on one side with a solid polymer electrolyte membrane interposed therebetween, and an anode is partitioned on the other side. This is a system that drives an external load with electric power generated by an electrochemical reaction with hydrogen supplied to a pole.
[0004]
Such a fuel cell system is provided with a fuel cell stack 100 as shown in FIG. The fuel cell stack 100 is obtained by integrally stacking a single cell that generates electric power with one membrane interposed therebetween, for example, several times in a horizontal direction so that the electrode surface is vertical, and tightened with a bolt or the like. is there.
The single cell has a polymer electrolyte membrane M, electrode catalyst layers C and C, as shown in FIG.
It is composed of gas diffusion layers D, D, separators SA, SH, and the like. Note that a structure in which the electrode catalyst layer C and the gas diffusion layer D are provided on one side of the polymer electrolyte membrane M and the electrode catalyst layer C and the gas diffusion layer D are provided on the other side may be referred to as a membrane electrode assembly MEA. Reference symbol RS in FIG. 4B is a rubber seal material.
[0005]
Among these constituent members, the separators SA and SH are used for providing a connection (stacking function) between cells in which a plurality of single cells are stacked to obtain a required voltage. Function is also required.
(1) A function to secure a supply passage for supplying hydrogen or air to cells in the fuel cell stack 100.
(2) A function of securing a supply passage of a coolant for cooling the fuel cell stack 100.
(3) Function to collect and extract current (electrons).
[0006]
Such separators SA and SH are stacked as described above when formed as a fuel cell stack (see FIG. 4 (a)), but the separator SA in a unit cell, which is one constituent unit, is formed. Air tightness and liquid tightness are required between the separator and the separator SH 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 on the fuel cell stack 100 or dewed water, a waterproof structure of the stack container is adopted.
Specifically, various fluids (anode gas, cathode gas, refrigerant) are sandwiched between the separator SA and the separator SH by inserting a rubber seal material (fluorine, EPDM, etc.) molded separately from the separators SA and SH. Function as a seal for use, a passage for various fluids, or a support for holding a load (function as a packing material and a cushion material). Here, Patent Document 1 discloses that seals are integrally formed on both front and back surfaces of the separators SA and SH.
[0007]
[Patent Document 1] JP-A-11-129396
The metal separator according to Patent Document 1 is formed by injection molding a silicone resin layer having a thickness of 0.05 mm to 1.0 mm and a hardness (JIS K6301 spring type hardness test A type) of at least 40 to 70 on at least one surface of a thin metal plate. It was formed by: According to this method, man-hours for assembling can be reduced, and forgetting of assembling, improper assembling and the like can be prevented.
[0009]
Further, in the fuel cell stack 100 using the metal separators SA and SH, there is a possibility that a liquid junction between the cells due to the refrigerant, the reaction product gas, the dew water, or the like may occur in the communication holes 110, and the separators SA and SH may be used. Electric corrosion of SH is a concern.
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 may be considered.
[0010]
[Problems to be solved by the invention]
However, according to the injection molding method, when a rubber material is molded on the front and back of a thin metal plate separator as a cushion material for a fuel cell, a packing material spacer, and a sealing material for preventing gas leakage, the pressure of the rubber at the time of molding causes the separation of the separator. Significant deformation is a problem.
Further, in the injection molding method, a material usable as a seal is limited to a silicone resin layer, and cannot be applied to a case where another rubber component is used as a base material.
On the other hand, when two-color molding is performed, the number of assembling steps is increased, so that there is a problem that the cost is high.
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 fuel cell separator with a seal that realizes an insulating structure of a stack body to improve waterproof performance, and a method for manufacturing a separator 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 problem, and the invention according to claim 1 is directed to manufacturing a fuel cell separator with a seal having seals on at least one end of the fuel cell separator. A method of temporarily forming a rubber composition to form a temporarily formed seal, a holding step of inserting the separator into the temporarily formed seal, and forming the temporarily formed seal and the separator in a vulcanization mold. And finally vulcanizing the temporary molded seal to form a molded product.
[0012]
According to the first aspect of the present invention, the separator and the seal can be integrally molded by inserting the separator between the temporarily molded seals having the required shape and thus temporarily molded. It is possible to efficiently and accurately manufacture a seal from the rubber composition without significantly deforming the seal.
[0013]
Here, the “temporary molded seal” means a sealing material having desired performance after being vulcanized by the method according to the present invention. The term “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.
Further, 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 a seal composed of a rubber composition. In the present invention, such conventional means can be used for the purpose of completely vulcanizing the seal and volatilizing impurities.
[0014]
According to a second aspect of the present invention, in the method of manufacturing a fuel cell separator with a seal according to the first aspect, the separator with the seal includes a communication hole sealing portion that covers an inner portion of the communication hole of the separator and the communication hole. And an outer peripheral seal portion that covers the outer peripheral portion of the separator from the outer peripheral portion, and the inner wall surface seal portion and the outer peripheral seal portion are temporarily formed using a rubber composition having an insulating property in the temporary molding step. In the holding step, the separator and the temporarily formed seal are bonded with an insulating primer-adhesive.
With this configuration, it is possible to prevent (1) a liquid junction inside the fuel cell due to the refrigerant, the reaction product gas, the dew water, and the like, and (2) to prevent a ground fault due to the wet and dew water. This makes it possible to manufacture a fuel cell separator with a seal that can secure insulation by an adhesive having an insulating effect even when the seal portion has a defect.
[0015]
A fuel cell separator with a seal having such a configuration is novel. Therefore, the invention according to claim 3 is a fuel cell separator with a seal having seals on at least one end of the fuel cell separator, and a communication hole sealing portion covering an inner portion of the communication hole of the separator. A fuel cell separator with a seal, characterized in that the fuel cell separator has an outer peripheral sealing portion that covers from an outer portion of the communication hole to an outer peripheral portion of the separator.
With this configuration, it is possible to prevent (1) a liquid junction inside the fuel cell due to the refrigerant, the reaction product gas, the dew water, and the like, and (2) to prevent a ground fault due to the wet and dew water. It becomes possible.
According to a fourth aspect of the present invention, in the separator with the seal according to the third aspect, the separator and the seal portion are further bonded by an insulating primer-adhesive.
With this configuration, it is possible to prevent (1) a liquid junction inside the fuel cell due to the refrigerant, the reaction product gas, the dew water, and the like, and (2) to prevent a ground fault due to the wet and dew water. In addition to this, even when the seal portion has a defect, the insulating property can be ensured by the adhesive having an insulating effect.
[0016]
BEST MODE FOR CARRYING OUT 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 sectional view of a single cell using a fuel cell separator with a seal according to the present embodiment.
[0017]
As shown in FIG. 1, a unit cell 1 includes a fuel cell separator with a seal 10 according to the present embodiment so as to sandwich a polymer electrolyte membrane M, electrode catalyst layers C, C, and gas diffusion layers D, D. 10 are arranged.
The fuel cell separator 10 with a seal is formed by integrally molding a plate-shaped separator 11 and seals 12, 12 arranged on both sides of the separator 11.
[0018]
The separator 11 is used in a fuel cell stack formed by stacking the unit cells 1 to have a connection (stacking function) between the cells to obtain a required voltage by stacking a plurality of unit cells 1. Things.
[0019]
The material of the separator 11 may be, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, a thin metal plate having a surface treatment for corrosion protection, or a synthetic graphite or a carbon-based material obtained by mixing graphite and a resin. Although it is preferably used, it is not particularly limited. The thickness of the separator 11 is not particularly limited, but is assumed to be about 0.05 to 0.3 mm in the present embodiment.
[0020]
The seal 12 is formed from a rubber composition. In the present embodiment, the seal 12 is formed so as to cover a part of the front and back surfaces of both ends of the separator 11 and to have a convex shape on a part of the front surface and the back surface of the thinly covered portion. The thickness of the portion to be thinly covered on the basis of the surface is about 0.05 to 0.3 mm, and the height of the convex portion is about 1 mm.
The composition used in the present invention is a composition for forming a sealing material by vulcanization, and is generally mainly composed of a rubber component, a vulcanizing agent, and a vulcanization accelerator. Various known additives can be added.
The rubber component used in the present invention is not limited, for example, nitrile rubber, silicone rubber, fluoro rubber, acrylic rubber, styrene butadiene rubber, ethylene propylene rubber, ethylene tetrafluoride resin, acrylonitrile butadiene rubber, Various synthetic rubbers and natural rubbers (NBR) of isoprene rubber, butadiene rubber, butyl rubber, chloropyrene rubber, ethylene propylene diene (EPDM) rubber, urethane rubber, chlorosulfonated polyethylene rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, or these Blends.
These rubber components can be appropriately selected according to the properties of the seal to be formed.
[0021]
The vulcanizing agent, the vulcanization accelerator and the amount of the vulcanizing agent 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, and thiuram-disulfide, and examples of the vulcanizing accelerator include guanidines, thioureas, thiazoles, and dithiocarbamates.
Further, as other components, a coloring agent, for example, titanium oxide, red iron oxide, ultramarine, carbon black, or the like may be added.
A composition composed of such components generally becomes a viscous fluid when heated.
[0022]
A method of manufacturing the separator 10 for a fuel cell with a seal by integrally molding the separator 11 and the seal 12 will be described below.
2A and 2B are diagrams illustrating a manufacturing process of a fuel cell separator with a seal, in which FIG. 2A is a diagram in which a rubber composition is temporarily molded to form a temporarily molded seal, and FIG. (C) is a diagram in which the temporary molding seal is fully vulcanized while holding the seal and the separator, and (d) is a diagram of the molded product.
[0023]
First, as a first step, the rubber composition 12a is provisionally molded (temporary molding step; see FIG. 2A).
The temporary molding step is a step for molding the rubber composition 12a into a temporary molded seal 12b having a predetermined shape. Absent.
Since the provisional molding seal 12b is formed on the front and back 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, according to the selected component in the rubber composition 12a, under a condition that the rubber composition 12a has a predetermined shape, a conventionally known method for molding a rubber component, for example, a transfer molding, The composition 12a is formed into a temporarily formed seal 12b.
For example, in the rubber composition 12a, the selected rubber component is ethylene propylene rubber (EPDM), and when this is molded by transfer molding, molding is performed at a temperature of about 60 to 170 ° C. for about 2 minutes. In this way, the rubber composition 12a becomes a temporary molded seal 12b having a predetermined rubber shape.
[0024]
As a second step, the separator 11 is inserted into the temporarily formed seal 12b (a clamping step; see FIG. 2B).
In the sandwiching step, the separator 11 is placed on the front (or back) temporary molding seal 12b formed in the temporary molding step, and the rear (or front) temporary molding seal 12b is covered from above. set.
In the insert, in the next step, a conventionally known adhesive may be applied to the temporarily formed seal 12b or the separator 11, or both, in order to prevent the displacement of the seal formed on the separator.
[0025]
As a third step, the temporarily formed seal 12b is fully vulcanized to form a seal 12 having a desired elasticity (full vulcanization step; see FIG. 2 (c)).
In the main vulcanization step in the present embodiment, main vulcanization of the temporary formed seal 12b is performed while holding the temporary formed seal 12b and the separator 11 in a vulcanizing 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 molded seal 12b into which the separator 11 is inserted is pressurized (for example, 7.8 to 14.3). Vulcanization at a temperature of about 150 to 180 ° C. until vulcanization is completed. By performing the main vulcanization in this way, the seals 12 having desired properties can be formed on the front and back of the separator.
[0026]
As a fourth step, the molded fuel cell separator 10 with a seal (see FIG. 2D) obtained in the main vulcanization step may be further subjected to secondary vulcanization (secondary vulcanization step).
The secondary vulcanization step is not always a necessary step in the present invention, and can be appropriately performed as desired.
In the case of performing the secondary vulcanization step, in the above-described main vulcanization step, vulcanization is not performed until a seal 12 having desired properties is obtained, and the seal is formed on the front and back surfaces of the separator 11 (the provisional molding seal 12b and the seal 12). Vulcanization is performed for about 12 hours). Next, in a 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 are obtained in the present embodiment.
The separator 11 and the seal 12 can be integrally formed by inserting the separator 11 between the temporarily formed and temporarily formed seals 12b having a required shape, so that the rubber can be formed without significantly 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 terms of time, and mass production becomes easy.
In addition, by including the secondary vulcanization step, the seal 12 can be completely vulcanized and the impurities can be volatilized.
[0029]
Furthermore, since the rubber composition 12a, which was difficult to mold with the conventional technology, can be molded into a complicated 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.
[0030]
The embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications are possible. For example, in the present embodiment, the seals 12 are formed at both ends of the separator 11, but the present invention is not limited to this, and the seals 12 may be formed only at one end.
In the present embodiment, the seal 12 is formed only on the end of the separator 11, but the present invention can be applied to a case where a seal is formed on other portions.
Further, for example, the present invention can be applied to the production of general metal plates with seals, such as electronic product parts. It goes without saying that the shape, thickness, height and the like of the seal or the separator can be changed as appropriate.
[0031]
Next, another embodiment of the present invention will be described with reference to FIG.
FIG. 3 is a schematic view showing a state where fuel cell separators with seals according to specific embodiments of the present invention are stacked.
As shown in FIG. 3A, the fuel cell separator 20 with a seal according to this embodiment has the outer peripheral seal portions 22a, 22a made of a rubber composition having insulating properties at both ends of the separator 21, and has insulating properties. It has communication hole seal portions 22b, 22b made of a rubber composition. Each outer peripheral seal portion 22a is an insulating rubber seal formed from the communication hole 23 on the end side (outside) of the separator 21 to the end 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 desired effects of the present invention are achieved. However, in consideration of rubber insulation, moldability, and assembly of the fuel cell stack, the thickness is 0.05 to 0.4 mm. Is preferably within the range.
[0032]
With this configuration, insulating seal portions (22a, 22b) are formed on both sides of the communication hole of the separator 21, and a fuel such as a refrigerant, reaction product water, dew water, or the like as indicated by an arrow X in FIG. Liquid junction inside the battery can be prevented.
As shown in FIG. 3, when the fuel cell separators 20 with a seal 20 and 20 ′ according to the specific embodiment of the present invention are arranged in an overlapping manner, the outer peripheral sealing portion 22 a (lower portion) of the fuel cell separator 20 with a seal is disposed. Side) and the outer peripheral sealing portion 22a '(upper side) of the fuel cell separator 20' with seal. Therefore, it is possible to prevent the ground fault due to the refrigerant, the wetted water, the dew condensation water and the like as shown by the arrow Y in FIG.
[0033]
The separator 21 and each seal portion are bonded to each other with an insulative insulating primer-adhesive (not shown) even if there is a defect in the rubber coating, or if a defect occurs due to fatigue of the seal portion. Even so, the insulating primer-adhesive ensures insulation.
[0034]
Such a fuel cell separator with seal 20 of the present invention shown in FIG. 3 can be manufactured by the manufacturing process shown in FIG.
That is, a material having a high insulating property is selected as the rubber composition, and a temporary molding step is performed using a vulcanizing mold for forming the communication hole seal portion and the outer peripheral portion seal portion. By applying an insulating primer-adhesive to each of the seal portions or both of them, it is possible to manufacture the sealed fuel cell separator 20 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, the separator and the seal can be integrally molded by inserting the separator between the temporarily molded seals having the required shape and being temporarily molded. It is possible to efficiently and accurately manufacture a seal from the rubber composition without significantly deforming the seal.
According to the second aspect of the invention, it is possible to prevent (1) a liquid junction inside the fuel cell due to a refrigerant, a reaction product gas, dew condensation water, and the like, and (2) a ground fault due to wet water, dew condensation water, and the like. It is possible to manufacture a fuel cell separator with a seal that can secure insulation by an adhesive having an insulating effect even if the seal portion has a defect.
According to the third and fourth aspects of the present invention, it is possible to prevent (1) a liquid junction inside the fuel cell due to a refrigerant, a reaction product gas, dew condensation water and the like, and (2) water and dew condensation water. It is possible to prevent ground faults due to the above-mentioned factors, and (3) it is possible to secure insulation by using an adhesive having an insulating effect even when there is a defect in the seal portion.
[Brief description of the drawings]
FIG. 1 is a sectional view of a single cell using a fuel cell separator with a seal according to the present embodiment.
2A and 2B are diagrams illustrating a manufacturing process of a fuel cell separator with a seal, in which FIG. 2A is a diagram in which a rubber composition is temporarily molded to form a temporarily molded seal, and FIG. (C) is a diagram in which the temporary molding seal is fully vulcanized while holding the seal and the separator, and (d) is a diagram of the molded product.
FIG. 3 is a schematic view showing a state in which fuel cell separators with seals according to specific embodiments of the present invention are stacked.
FIG. 4A is a perspective view showing the appearance of a conventional fuel cell stack, and FIG. 4B is an enlarged view of the configuration of the single cell of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Single cell 10 Separator for fuel cells with 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 both sides of at least one end of the fuel cell separator,
A temporary molding step of temporarily molding the rubber composition to form a temporary molded seal,
A clamping step of inserting the separator into the temporary molded seal,
Main vulcanization step of holding the temporary molded seal and the separator in a vulcanization mold, and finally vulcanizing the temporary molded seal to form a molded product,
A method for producing a fuel cell separator with a seal, comprising: The separator with a seal has a communication hole sealing portion covering the communication hole inside portion of the separator and an outer peripheral portion sealing portion covering from the outside portion of the communication hole to the outer peripheral portion of the separator,
The inner wall surface sealing portion and the outer peripheral portion sealing portion are temporarily formed using a rubber composition having an insulating property in the temporary molding step,
The method for producing a separator for a fuel cell with a seal according to claim 1, wherein in the holding step, the separator and the temporarily formed seal are adhered with an insulating primer-adhesive. A fuel cell separator with a seal having seals on the front and back of at least one end of the fuel cell separator, wherein a communication hole sealing portion covering a communication hole inside portion of the separator and a separator from an outside portion of the communication hole are formed. A fuel cell separator with a seal, comprising an outer peripheral seal portion covering the outer peripheral portion. 4. The separator for a fuel cell with a seal according to claim 3, wherein the separator and the seal portion are bonded with an insulating primer-adhesive.

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