JP4232273B2 - Separator for fuel cell and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing separators for fuel cells, and more particularly relates to a process for the preparation of separators for a fuel cell which is formed by resin containing a small member which is formed of a conductive material.
[0002]
[Prior art]
Conventionally, as a separator for this type of fuel cell, a separator formed by forming an expanded graphite layer on the surface of a carbon plate made of a steel body material (for example, Japanese Patent Application Laid-Open No. 62-272465, etc.) has been proposed. ). This separator is formed by molding a carbon plate such as a graphite carbon plate and forming an expanded graphite sheet, and holding the molded carbon plate with the expanded graphite sheet at a temperature of 170 ° C. and a molding pressure of about 10 MPa. Yes. Thus, it is said that sufficient conductivity is obtained by pressure bonding an expanded graphite sheet excellent in conductivity to the surface, and sufficient strength is obtained by using a carbon plate of a steel body material. .
[0003]
[Problems to be solved by the invention]
However, the separator obtained by pressure-bonding an expanded graphite sheet to the surface of the carbon plate described above has a problem that there are many manufacturing processes. That is, it is necessary to form the carbon plate and the expanded graphite sheet separately, and it is also necessary to press-bond them. Such multi-step manufacturing also raises the problem of increased costs.
[0004]
Method for producing a separator for the onset Ming fuel cell, it is another object to produce a separator having sufficient strength and has a sufficient conductivity easily. Another object of the method for producing a separator for a fuel cell of the present invention is to produce a separator having sufficient conductivity and sufficient strength at low cost.
[0005]
[Means for solving the problems and their functions and effects]
Method for producing separators for a fuel cell of the present invention employs the following means in order to achieve at least part of the above objects.
[0010]
The first method for producing a separator for a fuel cell according to the present invention comprises:
A method of manufacturing a separator for a fuel cell formed of a resin containing a micro member formed of a conductive material,
A first injection molding step of injection-molding a resin with a small content of the micro member out of two types of resins having different content of the micro member into a mold;
A second injection molding step of opening a predetermined amount of the mold in a state in which the injection-molded resin is present, and injection-molding a resin having a high content out of the two types of resins into the mold opened by the predetermined amount; The gist is to provide.
[0011]
In the first fuel cell separator manufacturing method of the present invention, the mold is opened by a predetermined amount in the state where the resin injection-molded in the first injection molding step is present, and two types of molds are opened. By injection molding a resin having a high content among the above-mentioned resins, the inside is formed of a resin having a small content of fine members, and the outer surface is a separator formed of a resin having a high content of fine members, that is, sufficient A separator having electrical conductivity and sufficient strength can be manufactured. In addition, after the first injection molding step, it is only necessary to perform injection molding in a state where the mold is opened by a predetermined amount, and thus the above-described separator can be easily manufactured. Moreover, since it forms with resin containing the micro member, a separator can be manufactured cheaply. The meaning of “micro member” is the same as the separator for a fuel cell of the present invention.
[0012]
The method for producing the second fuel cell separator of the present invention comprises:
A method of manufacturing a separator for a fuel cell formed of a resin containing a micro member formed of a conductive material,
A resin preparation step of preparing the two types of resins so that the flowability of the resin having a high content of the micro members is higher than that of the other resin among the two types of resins having different contents of the micro members,
A first injection molding step of injection molding the highly fluid resin into a mold;
The gist of the present invention is that the injection-molded mold is provided with a second injection molding step of injection-molding the other resin.
[0013]
In this second method for producing a separator for a fuel cell according to the present invention, a resin containing a large amount of minute members having high fluidity is injection-molded to cause the resin to stick to the surface of the mold. The center portion of the mold can be formed by injection-molding a resin containing a small amount of minute members having low fluidity in the mold. That is, it is possible to manufacture a separator whose outer surface is molded with a resin containing a large amount of micro members and whose central portion is molded with a resin containing a small amount of micro members, that is, a separator having sufficient conductivity and sufficient strength. . In addition, since the two types of resins need only be prepared and injection-molded in order into the mold, the above-described separator can be easily manufactured. Moreover, since it forms with resin containing the micro member, a separator can be manufactured cheaply. The meaning of “micro member” is the same as the separator for a fuel cell of the present invention.
[0014]
In the first or second method for producing a separator for a fuel cell of the present invention, the micro member may be carbon particles, or the micro member may be carbon short fibers. it can. Moreover, the said micro member can also be formed with a metal material.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described using examples. FIG. 1 is a configuration diagram showing an outline of a configuration of a unit cell 21 constituting a fuel cell including a separator 30 manufactured by a method for manufacturing a fuel cell separator according to an embodiment of the present invention. The fuel cell is a polymer electrolyte fuel cell configured by stacking a plurality of single cells 21. As shown in the figure, the cell 21 includes an electrolyte membrane 22 that is a proton conductive membrane formed of a polymer material such as a fluorine resin, and a catalyst of platinum or an alloy made of platinum and other metals. An anode 23 and a cathode 24 as gas diffusion electrodes which sandwich the electrolyte membrane 22 on the surface formed by the carbon cloth formed and sandwiched the electrolyte membrane 22 to form a sandwich structure, and the anode 23 and the cathode 23 while sandwiching the sandwich structure from both sides The cathode 24 forms flow paths 36 and 38 for fuel gas and oxidant gas, and two separators 30 that form a partition wall between adjacent unit cells 21.
[0016]
Separator 30 includes a core layer 32 formed of a resin containing a ratio of about several% less than 10 wt% preferably carbon, core layer 32 preferably at least 10 wt% of the carbon in a proportion of more than 20 wt% And an outer layer portion 34 formed of the same resin. Various types of carbon such as fine particles of the order of μm or less, particles of the order of mm or less, and short fibers of the order of μm can be used. As the resin, various resins such as polypropylene, polyethylene, polybutylene, polyamide, polyoxymethylene, polystyrene, polyphenylene sulfite, and polyethylene terephthalate can be used. The joining portion between the core layer portion 32 and the outer layer portion 34 is schematically and clearly described in FIG. 1 for easy understanding, but is joined at a temperature equal to or higher than the melting point of the resin. The boundary is not clear and is mixed and mixed. In the embodiment, the core layer portion 32 and the outer layer portion 34 are formed using the same resin. However, different resins may be used as long as they are compatible resins.
[0017]
Thus, the separators 30, by forming the outer layer 34 on high carbon content resin, ensuring excellent conductivity in the outer layer portion 34, forming the core layer 32 with a small resin having a carbon content By doing so, sufficient strength as the separator 30 is obtained.
[0018]
It will now be described how the production of separators 30 was Hiroshi. Figure 2 is a manufacturing process diagram showing an example of the state of production of separators 30. As shown in process diagram, the production of separators 30 first preparing carbon content of high carbon-rich resin for forming the Kabonpua resin and the outer layer 34 with low carbon content for forming the core layer 32 The process is started (step S100). The carbon content, carbon type, and resin type are described above.
[0019]
The core layer portion 32 is injection molded using a mold for forming the separator 30 with the carbon poor resin among the two types of resins thus prepared (step S110). The mold used for injection molding is formed slightly smaller than the size of the separator 30 to be manufactured. Subsequently, the mold was slightly opened or slightly shifted while maintaining the injection-molded carbon poor resin in the center (step S120), and the desired size of the separator 30 was prepared (step S120). The outer layer portion 34 is injection molded with a carbon-rich resin (step S130). Since the carbon rich resin is injection-molded into the gap between the core layer portion 32 formed of the carbon poor resin and the mold, the carbon rich resin is formed on the outer surface of the core layer portion 32 formed of the carbon poor resin. A layer is formed to form the outer layer portion 34. In addition, since the injection molding of the carbon rich resin is performed at a temperature equal to or higher than the melting point of the resin, the outer surface of the core layer portion 32 is melted and mixed with the carbon rich resin to be integrated. In addition, the technique of performing injection molding twice using such a single mold is known as two-layer molding.
[0020]
According to separators 30 described above, it is possible to secure a high conductivity by forming the outer surface on high carbon content resin. Moreover, sufficient physical strength can be ensured by forming the core layer portion 32 with a resin having a low carbon content.
[0021]
According to the manufacturing method of the separator 30 of the embodiment, by using the technique of two-layer molding, inside less its outer surface carbon content can be carbon content is easily manufactured with the Ise separator 30 . In addition, since the injection molding of the carbon-rich resin is performed at a temperature equal to or higher than the melting point of the resin, the core layer portion 32 and the outer layer portion 34 can be easily integrated. Therefore, the process of bonding the core layer portion 32 and the outer layer portion 34 is not required. Since this way can be easily molded separators 30 by two kinds of resins, it is possible to reduce the manufacturing cost of the separator 30.
[0022]
Next, as a manufacturing method of the separators 30, a description will be given of a method different from the method described above (second manufacturing method). Figure 3 is a manufacturing process diagram showing an example of a state of a second production of separators 30. In the second manufacturing method of the separator 30, first, a low-flow resin with a low carbon content for forming the core layer portion 32 and a low flowability and a high flow with a high flowability with a high carbon content for forming the outer layer portion 34 are used. A step of preparing a resin is performed (step S200). Whether the fluidity is lowered or raised is determined by adjusting the molecular weight of the resin. That is, the molecular weight is adjusted high for the low flow resin, and the molecular weight is adjusted low for the high flow resin. The carbon content, carbon type, and resin type are the same as described above.
[0023]
Of the two types of resins thus prepared, injection molding is performed using a mold for forming the separator 30 with a high-flow resin (step S210). Unlike the manufacturing method described above, the mold used for injection molding is the size of the separator 30 to be manufactured. Subsequent to the injection molding using the high flow resin, the injection molding is performed using the low flow resin before the high flow resin is solidified (step S220). When the low flow resin is injection-molded in this way, the high flow resin is stuck on the surface of the mold, but the center portion is replaced with the low flow resin. Of course, the injection molding of the low-flow resin is performed at a temperature equal to or higher than the melting point, and is performed before the high-flow resin is solidified. Therefore, the joint portion between the low-flow resin and the high-flow resin is compatible and integrated.
[0024]
In the second manufacturing method of the separator 30 of the embodiment described above, the internal fewer carbon content its outer surface can be carbon content is easily manufactured with the Ise separator 30. Moreover, since the injection molding of the low flow resin is performed before the high flow resin is hardened yet, the core layer portion 32 and the outer layer portion 34 can be easily integrated. Therefore, the process of bonding the core layer portion 32 and the outer layer portion 34 is not required. Since this way can be easily molded separators 30 by two kinds of resins, it is possible to reduce the manufacturing cost of the separator 30.
[0025]
In the manufacturing method of separator 30 of the example, carbon is contained in the resin. However, for the purpose of ensuring conductivity and strength, any material can be used as long as it has conductivity instead of carbon. It may be a thing. For example, metal powder or metal fiber may be used.
[0026]
In separators 30 has been described as a separator for use in a polymer electrolyte fuel cell, may alternatively be used in any fuel cell if operable fuel cell temperature below the melting point of the resin.
[0027]
The embodiments of the present invention have been described using the embodiments. However, the present invention is not limited to these embodiments, and can be implemented in various forms without departing from the gist of the present invention. Of course you get.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an outline of a configuration of a unit cell 21 constituting a fuel cell including a separator 30 manufactured by a method for manufacturing a fuel cell separator according to an embodiment of the present invention.
2 is a manufacturing process diagram showing an example of the state of the first production of the separators 30.
3 is a manufacturing process diagram showing an example of a state of a second production of separators 30.
[Explanation of symbols]
21 unit cell, 22 electrolyte membrane, 23 anode, 24 cathode, 30 separator, 32 core layer part, 34 outer layer part, 36, 38 flow path.

Claims (5)

A method of manufacturing a separator for a fuel cell formed of a resin containing a micro member formed of a conductive material , wherein the content of the micro member of two types of resins having different contents of the micro member A first injection molding step in which a small amount of resin is injection-molded into the mold, and a predetermined amount of the mold is opened in a state where the injection-molded resin is present inside, and the predetermined amount of the mold contains one of the two types of resins. A method for producing a separator for a fuel cell, comprising: a second injection molding step of injection molding a large amount of resin . A method of manufacturing a separator for a fuel cell formed of a resin containing a micro member formed of a conductive material , wherein the content of the micro member of two types of resins having different contents of the micro member A resin preparation step of preparing the two types of resins so that the flowability of a large amount of resin is higher than that of the other resin, a first injection molding step of injection-molding the high flowability resin into a mold, and the injection the second injection molding step in the method of manufacturing the separator for a fuel cell comprising injection molding said other resin molded type. The minute member, manufacturing method of a separator for a fuel cell according to claim 1 wherein a carbon particle. The minute member, manufacturing method of a separator for a fuel cell according to claim 1 or 2 wherein the carbon short fibers. The minute member, manufacturing method of a separator for a fuel cell according to claim 1 or 2 wherein becomes formed of a metal material.

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