JP2001313044A - Separator for fuel cell and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator for a fuel cell with excellent conductivity, gas impermeability, and strength at low cost, and to provide a manufacturing method of the same. SOLUTION: For the manufacturing method of separators 1A, 1B, 1C for the fuel cell, the separators 1A, 1B, 1C for the fuel cell are formed into shape by heating and pressing the mixture of binder including bisphenol compounds and epoxy resin, and carbon powder, by a mold with prescribed shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a fuel cell separator and a fuel cell separator.

[0002]

2. Description of the Related Art In order to reduce air pollution as much as possible, it is important to take measures against exhaust gas from automobiles, and as one of the measures, electric vehicles are used. Has not been reached.

[0003] Fuel cells have been attracting attention as clean power generation devices that generate no electricity other than water using hydrogen and oxygen by a reverse reaction of electrolysis, and automobiles using fuel cells are the most promising. It is considered to be a clean car with a certain quality. Among the fuel cells, solid polymer electrolyte fuel cells are most promising for automobiles because they operate at low temperatures.

[0004] A solid polymer electrolyte fuel cell generally has a large number of cells stacked, and a cell is formed by joining a solid polymer electrolyte membrane between two electrodes (a fuel electrode and an oxidizer electrode) with a solid polymer electrolyte membrane interposed therebetween. It has a structure in which a joined body of a polymer electrolyte membrane and an electrode is sandwiched between separators having a gas passage for a fuel gas or an oxidizing gas.

[0005] The fuel cell separator has one surface exposed to a fuel gas containing hydrogen as a main component and the other surface exposed to an oxidizing gas such as air, and has a role of shutting off each other's gases. Further, a part of the fuel cell separator may be exposed on one side to a cooling medium such as cooling water. In terms of shape, the surface of the separator is generally engraved with a groove pattern forming a gas passage in order to realize a gas flow intended by the designer. The fuel cell separator has a role and a role of transmitting electricity generated by the cell.

[0006] Further, for a mobile body such as an automobile, it is necessary to be lightweight for improving fuel efficiency.

[0007] Therefore, the main performance required of the fuel cell separator is that it is difficult to permeate the fuel gas and the oxidizing gas, that the electric resistance is low, that it is chemically stable, and that the strength required as a part is high. And light weight.

In order to achieve these performances, as a prior art 1, Japanese Patent Application Laid-Open No. 60-246568 discloses a technique in which a phenol resin is added as a binder to carbon powder such as artificial graphite powder and natural graphite powder and kneaded. A method for producing a fuel cell separator by heating and pressing a resin in a mold having a predetermined shape at a temperature at which the resin does not graphitize is disclosed.

As prior art 2, Japanese Patent Application Laid-Open No. 9-227
JP-A-08-2008 discloses a method of manufacturing a fuel cell separator by using a phenol resin and an epoxy resin as a binder to be added to carbon powder, and hot-pressing the resin in a mold having a predetermined shape at a temperature at which the resin does not graphitize. Have been.

[0010]

However, in the prior art 1, when the phenol resin is thermally cured in the hot pressing step, the hydroxyl groups in the resin react to generate water vapor, so that bubbles are generated in the separator and the gas in the separator is generated. At the same time, the impermeability may become insufficient, and at the same time, the contact between the graphite powders becomes insufficient and the electrical resistivity tends to increase.

In the prior art 2, since a phenol resin and an epoxy resin are used for the binder, no water vapor is generated from the binder during thermosetting, and the separator obtained by hot press molding has a sufficient gas impermeability. However, since both phenolic resin and epoxy resin are polymerized, contact between graphite powders becomes insufficient due to high resin melt viscosity during hot press molding, and electrical resistivity may increase. There is. In order to lower the electrical resistivity, a method of reducing the amount of binder added and a method of increasing the surface pressure during hot pressing are used.However, the former causes a decrease in strength, and the latter leads to an increase in the size of the heating press and the mold. There is a problem that costs increase.

The present invention has solved the above-mentioned problems, and provides a method for manufacturing an inexpensive fuel cell separator excellent in electric conductivity, gas impermeability, and strength, and a fuel cell separator.

[0013]

Means for Solving the Problems In order to solve the above technical problems, the technical measures taken in claim 1 of the present invention (hereinafter referred to as first technical means) are bisphenols and epoxy resins. A method for producing a separator for a fuel cell, wherein a mixture containing a binder containing a resin and carbon powder is subjected to hot press molding using a mold having a predetermined shape.

The effects of the first technical means are as follows.

That is, since the viscosity of bisphenols at the time of thermal melting is low, and the hydroxyl groups of the bisphenols react with the epoxy groups of the epoxy resin to suppress the generation of water vapor, electric conductivity, gas impermeability and strength are reduced. A fuel cell separator with excellent surface pressure can be formed at a low surface pressure. Since molding can be performed with a low surface pressure, a small heating press and a mold can be used, so that an inexpensive fuel cell separator can be manufactured.

[0016] In order to solve the above technical problem, a technical measure taken in claim 2 of the present invention (hereinafter referred to as a second technical measure) is that the binder contains a phenol resin. 2. The method for producing a fuel cell separator according to claim 1, wherein:

The effects of the second technical means are as follows.

That is, by mixing a phenolic resin in the binder, the mechanical properties (flexural strength, flexural modulus, compressive strength, creep strength), heat resistance, chemical resistance and the like of the separator can be adjusted.

In order to solve the above technical problem, the technical means (hereinafter referred to as third technical means) taken in claim 3 of the present invention is that the content of the phenolic resin is equal to the total amount of the binder. 3. The method for producing a fuel cell separator according to claim 2, wherein the amount is 70% by weight or less. 4.

The effects of the third technical means are as follows.

That is, when the content of the phenol resin is 70
When the content is not more than wt%, molding can be performed without greatly reducing material fluidity.

In order to solve the above technical problem, the technical means (hereinafter referred to as a fourth technical means) taken in claim 4 of the present invention is characterized in that an epoxy group contained in the binder is The ratio of the hydroxyl group contained in the binder is 0.8 to 1.2, wherein the ratio is 0.8 to 1.2.
4. A method for producing a fuel cell separator according to any one of the items (1) to (3).

The effects of the fourth technical means are as follows.

That is, since the hydroxyl group contained in the binder sufficiently reacts with the epoxy group at the time of hot press molding, generation of water vapor from the binder can be sufficiently suppressed. The ratio of the hydroxyl group to the epoxy group is 1.
When it is larger than 2, the number of epoxy groups that can react with the hydroxyl group is small, and thus the generation of steam increases. On the other hand, when the ratio of the hydroxyl group to the epoxy group is less than 0.8, the amount of the epoxy group is large, so that it takes a long time to heat and cure, it takes a long time to manufacture the fuel cell separator, and the cost is increased.

In order to solve the above technical problem, the technical means (hereinafter referred to as the fifth technical means) taken in claim 5 of the present invention is that a curing accelerator of an epoxy resin is added to the mixture. Claim 1 characterized by being included
5. A method for producing a fuel cell separator according to any one of items 4.

The effects of the fifth technical means are as follows.

That is, since the curing accelerator is contained, the time for curing the binder by heating can be shortened, and the fuel cell separator can be manufactured in a short time.

The technical means (hereinafter referred to as sixth technical means) employed in claim 6 of the present invention for solving the above technical problem is described in any one of claims 1 to 5. A fuel cell separator manufactured using the method for manufacturing a fuel cell separator according to (1).

The effects of the sixth technical means are as follows.

That is, since the fuel cell separator is manufactured by the method for manufacturing an inexpensive fuel cell separator having excellent electric conductivity, gas impermeability and strength, it can be used for an inexpensive fuel cell excellent in air conductivity, gas impermeability and strength. A separator is created.

[0031]

FIG. 1 is a schematic partial sectional view showing an example of a fuel cell. The solid polymer electrolyte membrane 4 is joined and sandwiched between two electrodes (oxidant electrode 5 and fuel electrode 6). The solid polymer electrolyte membrane 4 includes an oxidizer electrode 5 and a fuel electrode 6
It is sandwiched and joined by. A gasket 7 made of ethylene propylene rubber is integrally formed by injection molding on a portion of the solid polymer electrolyte membrane 4 protruding from the oxidant electrode 5 and the fuel electrode 6. Solid polymer electrolyte membrane 4, oxidant electrode 5,
The electrode unit 3 is composed of the fuel electrode 6 and the gasket 7.

The electrode unit 3 is sandwiched between the separator 1A and the separator 1B or between the separator 1B and the separator 1C. That is, the separator 1A, the electrode unit 3, the separator 1B, the electrode unit 3, and the separator 1
One unit is configured by being stacked in the order of C. The fuel cell is configured by stacking a number of these units.

A gasket 7 is sandwiched between the separators 1A and 1B and between the separators 1B and 1C to seal a fuel gas containing hydrogen as a main component, an oxidizing gas such as air, and a cooling medium such as cooling water. ing. A gasket 7a is also provided between the separator 1A and the separator 1C to seal fuel gas, oxidizing gas and cooling water.

A fuel gas passage 11a through which fuel gas flows between the separator 1A and the electrode unit 3 and between the separator 1B and the electrode unit 3 is provided in each of the separators 1A and 1B. Between separator 1B and electrode unit 3, separator 1C and electrode unit 3
The oxidizing gas passage 11b through which the oxidizing gas flows,
It is provided in each of the separator 1B and the separator 1C. There is no electrode unit between the separator 1A and the separator 1C, and the cooling medium passage 1 through which the cooling medium flows.
1c is provided on the separator 1C and the separator 1A.

The present invention relates to a method of manufacturing the separators 1A, 1B, and 1C having a complicated shape such as such a passage, and to a separator. An example of the shape of the separator will be described using a separator 1C. FIG. 2 is a front view of the separator 1C as viewed from the oxidant electrode 5 side.

The separator 1C has a fuel gas supply hole 13, a fuel gas discharge hole 9, an oxidizing gas supply hole 15, and an oxidizing gas discharging hole 1 formed by a core during insert molding.
6. A cooling medium supply hole 17 and a cooling medium discharge hole 18 are provided.

The oxidizing gas supply hole 1b is formed in the separator 1C through an oxidizing gas passage 11b flowing downward from above in FIG.
The oxidizing gas inlet 19 for supplying the oxidizing gas from the oxidizing gas 5 and the oxidizing gas discharge hole 16
Is provided with an oxidizing gas outlet 20 for discharging the oxidizing gas. The oxidizing gas inlet 19 and the oxidizing gas outlet 20 are formed by insert molding rectangular hollow members 19a and 20a having a square cross section. The groove 8a is provided so that the projection of the gasket 7 abuts to seal the fuel gas, the oxidizing gas, and the cooling medium when assembled in the fuel cell.

The fuel gas supply holes 13, the fuel gas discharge holes 9,
The oxidizing gas supply hole 15, the oxidizing gas discharge hole 16, the cooling medium supply hole 17, and the cooling medium discharge hole 18 are also provided in the separators 1A and 1B and the gasket 7, and when assembled in the fuel cell, Supply manifold, fuel gas discharge manifold, oxidant gas supply manifold 15M, oxidant gas discharge manifold 16M,
A cooling medium supply manifold and a cooling medium discharge manifold are configured.

The method for producing a fuel cell separator proposed by the present inventors is based on scaly carbon powder such as natural graphite, artificial graphite, earthy graphite or the like, and bis (4-hydroxyphenyl) sulfone, bis (4 -Hydroxyphenyl) sulfide and other bisphenols and epoxy resin such as novolak-type epoxy resin and cresol novolak-type epoxy resin are added, kneaded, and heated and press-molded in a mold having a predetermined shape at a temperature at which the resin does not graphitize. This is a method for manufacturing a separator.

In general, the hot press molding temperature of a novolak type phenol resin having a softening point of 70 to 85 ° C., a phenol novolak type epoxy resin having a softening point of 60 to 75 ° C., and a cresol novolak type epoxy resin (140 to 250)
C), the melt viscosity is as high as several tens to several hundreds of Pa · s. Therefore, to obtain satisfactory separator performance (electrical conductivity, gas impermeability, strength heat resistance, creep resistance, corrosion resistance, etc.) It is required that the surface pressure during press molding be as high as 50 to 100 MPa.

To solve this problem, the present inventors have included bisphenols as a binder. Since bisphenols have a very low viscosity of 10 mPa · s or less at the time of hot melting, by using a binder combining bisphenols and an epoxy resin, a separator having sufficient performance at a surface pressure of 10 to 30 MPa during hot press molding is used. Is obtained.

The mixing ratio of the bisphenol and the epoxy resin is such that the ratio of the amount of the hydroxyl group of the bisphenol to the amount of the epoxy group of the epoxy resin subjected to the chemical reaction when subjected to a chemical reaction upon heating and thermosetting is 0.8. It is desirable to set it to be 1.2.

The following formula shows a chemical reaction formula between a bisphenol and an epoxy resin. Bisphenols react with the epoxy group to link the two epoxy groups,
Generation of steam from the hydroxyl group of bisphenols can be prevented.

[0044]

Embedded image That is, when only bisphenols are used as the binder, the hydroxyl groups of the bisphenols react during hot press molding to produce water, which becomes steam and appears as swelling inside the separator, gas impermeability, conductivity, The strength may be significantly reduced. When bisphenols and epoxy resin are used as the binder, the hydroxyl groups react with the epoxy groups, so that no water vapor is generated, and the separator is in a denser state, having a density close to the theoretical density, and is gas-impermeable and conductive. A separator having excellent strength and the like can be obtained. The density of the separator obtained by hot press molding is desirably 93% or more of the theoretical density.

When the ratio of the hydroxyl group to the epoxy group is larger than 1.2, the number of the epoxy groups that can react with the hydroxyl group is small, so that the generation of steam increases. On the other hand, when the ratio of the hydroxyl group to the epoxy group is smaller than 0.8, the amount of the epoxy group is large, so that it takes time to heat and cure, it takes time to manufacture the fuel cell separator, and the cost increases.

The bisphenols used as the binder in the present invention include bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide, 2,2-bis (4-hydroxyphenyl) propane, bisphenol F, , 2-bis (4-hydroxyphenyl) hexafluoropropane and the like.

Some of the bisphenols can be replaced with a phenolic resin having a hydroxyl group. By replacing a part of the bisphenols with a phenol resin, the mechanical properties (flexural strength, flexural modulus, compressive strength, creep strength), heat resistance, chemical resistance, etc. of the separator can be adjusted. It is desirable that the substitution ratio does not exceed 70 wt%. If the substitution ratio exceeds 70 wt%, the fluidity of the material decreases, and the surface pressure during hot press molding increases,
The hot press molding machine and the mold increase in size and cost.

When a part of bisphenols is replaced by a phenol resin, the total of the hydroxyl groups of the bisphenols and the phenol resin with respect to the amount of epoxy groups of the epoxy resin subjected to the chemical reaction when chemically cured by heating and thermally cured. It is desirable to set the ratio of the amounts to be 0.8 to 1.2.

The epoxy resin used as the binder of the present invention includes a phenol novolak type epoxy resin,
Bisphenol A novolak type epoxy resin, cresol novolak type epoxy resin, brominated novolak type epoxy resin, bisphenol A type epoxy resin and the like can be used.

An imidazole compound (1-cyanoethyl-2-ethyl-4) is used as a curing accelerator for the epoxy resin.
(5) -methylimidazole, 2-methylimidazoleamine, 1-benzyl-2-methylimidazole, 2-
Ethyl-4-methylimidazole, etc.), aromatic amine compounds (metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, etc.), dicyandiamide and the like may be used in combination. The addition amount of the imidazole compound is preferably 1% by weight or less, and the amount of the aromatic amine compound or dicyandiamide is preferably 5% by weight or less based on the epoxy resin.

The carbon powder used in the present invention is a flaky natural graphite having a particle size range of 0.5 to 250 μm,
It is a single powder or a mixed powder of artificial graphite, expanded graphite, coke, carbon black, graphite material cutting powder, earth graphite, and the like.

The mixing ratio of the binder and the carbon powder is as follows:
The binder is preferably 5 to 30% by weight and the carbon powder 70 to 95% by weight. When the binder is smaller than the above range, the strength of the separator is lowered or the gas permeability is reduced. On the other hand, when the binder is larger than this range, there is a problem that the conductivity is reduced.

In the method of manufacturing a separator according to the present invention, first, carbon powder as a main component is mixed at a predetermined ratio. This mixing step can be performed by a kneader, a ribbon mixer, a stick mixer, a Hängel mixer, an Erich mixer or the like.

Next, a solution binder obtained by dissolving a binder in a solvent is added at a predetermined ratio, and the carbon powder and the binder are sufficiently mixed and dispersed to obtain a mixture. After removing the solvent into a powder or granule by removing the solvent, a predetermined amount of the mixture is poured into a heated mold having a predetermined shape, and a mold temperature of 1
Heat press molding is performed at 40 to 280 ° C and a surface pressure of 10 to 50 MPa. If the formed separator is not completely cured, it is heated at 160 to 280 ° C. in a predetermined heating furnace.
It is desirable to complete the curing by heating for up to 300 minutes.

Hereinafter, embodiments of the present invention will be described in detail.

(Example 1) In Example 1, bisphenols and epoxy resin were used as binders. As bisphenols, bis (4-hydroxyphenyl) sulfide having a hydroxyl equivalent of 111 gram equivalent was used. The epoxy resin has an epoxy equivalent of 210
A gram equivalent of bisphenol A novolak epoxy resin was used. Ethyl acetate was used as a solvent for dissolving the binder. As carbon powder, the particle size range is from 0.5 to
A flaky artificial graphite powder (KS-75, manufactured by LONZA) having a size of 128 μm and an average particle size of 75 μm was used.

A mixture of carbon powder, an ethyl acetate solution of bisphenols (concentration: 80 wt%) and an epoxy resin ethyl acetate solution (concentration: 15 wt%) was mixed and kneaded with a Hexchel mixer in a combination shown in Table 1, and the solvent was removed. After granulation, the test mold (10 mm x 85 mm)
An amount of the thickness of about 3.5 mm is introduced, and the surface pressure is 30M.
Press molding was performed under the conditions of Pa, a mold temperature of 200 ° C., and a pressing time of 10 minutes. Thereafter, post-curing was performed in a heating furnace at 160 to 180 ° C. for 60 minutes to produce a test molded product. The evaluation of the test molded article was performed based on the relative density, the electrical resistivity, and the bending strength. The relative density was obtained by measuring the density of the test molded article (molded article density) and calculating the ratio of the molded article density to the theoretical density, that is, the molded article density / theoretical density. Further, the electrical resistivity in the pressing direction of the hot press molding of the test molded article was measured. Furthermore, the distance between supporting points is 60 mm, and the test speed is 2 mm / m.
Under the conditions of “in”, the bending strength was measured with the pressing direction of hot press molding of the test molded product as the load direction (JIS K7).
203).

(Example 2) In Example 2, a bisphenol and an epoxy resin different from those in Example 1 were used as a binder. As bisphenols, bis (4-hydroxyphenyl) sulfone having a hydroxyl equivalent of 127 gram equivalent was used. As the epoxy resin, an oxocresol novolak type epoxy resin having an epoxy equivalent of 220 g equivalent was used. Ethyl acetate was used as a solvent for dissolving bis (4-hydroxyphenyl) sulfone, and 2-butanone was used as a solvent for dissolving oxocresol novolak type epoxy resin. The same carbon powder as in Example 1 was used.

A test molded article was produced in the same manner as in Example 1 using a combination of carbon powder, an ethyl acetate solution of bisphenols (concentration: 80 wt%) and an epoxy resin 2-butanone solution (concentration: 15 wt%) as shown in Table 2. did. The evaluation was performed in the same manner as in Example 1.

Example 3 In Example 3, bisphenols, a phenol resin and an epoxy resin were used as the binder. The same carbon powder, bisphenols, epoxy resin and solvent as in Example 1 were used. As a phenol resin, the hydroxyl equivalent is 11
0 gram equivalent of novolak phenolic resin was used.

Examples of combinations of carbon powder, an ethyl acetate solution of bisphenols (concentration: 80 wt%), an epoxy resin ethyl acetate solution (concentration: 15 wt%), and a phenol resin ethyl acetate solution (concentration: 15 wt%) are shown in Table 3. A test molded article was produced in the same manner as in Example 1, and evaluated in the same manner as in Example 1.

Example 4 In Example 4, the same carbon powder, bisphenols, epoxy resin and solvent as those in Example 1 were used, and a curing accelerator was used. 1-cyanoethyl-2-ethyl-4 (5) -methylimidazole was used as a curing accelerator. Ethyl acetate solution of carbon powder and bisphenols (concentration 80w
t%) and an ethyl acetate solution of an epoxy resin (concentration 15 wt.
%) And a curing accelerator are mixed and kneaded in a combination shown in Table 4 with a Hexchel mixer, and the solvent is removed to obtain granules. Then, the thickness of the mixture is reduced to a test mold (10 mm × 85 mm). An amount of about 3.5 mm was charged and press-molded under the conditions of a surface pressure of 30 MPa, a mold temperature of 180 ° C., and a pressurizing time of 10 minutes to produce a test molded product. The evaluation was performed in the same manner as in Example 1.

Comparative Example 1 In Comparative Example 1, a phenol resin and an epoxy resin were used as a binder. The same carbon powder and solvent as in Example 1 were used. As a phenol resin, a novolak-type phenol resin having a hydroxyl equivalent of 110 gram equivalent was used. As an epoxy resin, an oxocresol novolak type epoxy resin having an epoxy equivalent of 220 g equivalent (epoxy resin)
Was used.

Example 1 was prepared by combining a carbon powder, a phenol resin in ethyl acetate solution (concentration: 80 wt%) and an epoxy resin in ethyl acetate solution (concentration: 15 wt%) as shown in Table 5.
A test molded article was produced in the same manner as in Example 1. Evaluation is also Example 1
Performed in the same manner as

(Comparative Example 2) In Comparative Example 1, only a phenol resin was used as a binder. The same carbon powder and solvent as in Example 1 were used. A novolak type phenol resin having a softening point of 80.5 ° C., a gel time of 385 seconds (at 150 ° C.), and a fluidity of 190 mm (at 125 ° C.) was used as the phenol resin, and hexamethylenetetramine was used as a curing agent for the phenol resin.

A molded article for testing was produced in the same manner as in Example 4 using a combination of carbon powder, an ethyl acetate solution of phenolic resin (concentration: 80 wt%) and a curing agent as shown in Table 5. The evaluation was performed in the same manner as in Example 1.

(Evaluation Results) Examples 1 to 4, Comparative Examples 1 and 2
Are shown in Tables 1 to 6 and graphed in FIGS. FIG. 3 is a graph showing the relationship between the amount of binder added to the carbon powder and the relative density. FIG. 4 is a graph showing the relationship between the amount of binder added to the carbon powder and the electrical resistivity. FIG. 5 is a graph showing the relationship between the amount of binder added to the carbon powder and the bending strength.

Except for Comparative Example 2 in which no epoxy resin was contained in the binder, the relative density increased as the amount of binder added increased, regardless of the type of binder.
When the amount of the binder added exceeds 15% by weight, the binder becomes stable.
In Comparative Example 2, when the binder amount was 5 wt%, the relative density was considerably low, and when the binder amount was 10 wt% or more, the relative density increased with the binder amount.

Regardless of the type of binder, the electrical resistivity decreases as the amount of binder added decreases. Regardless of the type of binder, the flexural strength increases as the amount of binder added increases, and becomes stable when the amount of binder exceeds 15 wt%.

Examples 1, 2, and 4 have almost the same performance in relative density, electrical resistivity, and bending strength. Example 3 in which a phenol resin was added to the binder was used in Examples 1, 2, and 4.
However, the relative density and the bending strength are slightly lower and the electrical resistivity is slightly higher. On the other hand, Comparative Examples 1 and 2
Compared with Examples 1 to 4, the relative density and the bending strength are considerably lower, and the electric resistivity is considerably higher.

That is, the combination of the bisphenols and the epoxy resin of the present invention is several times better than the combination of the phenol resin and the epoxy resin of the comparative example or only the phenol resin. As described above, a bisphenol having a low viscosity at the time of thermal melting can be molded at a low surface pressure and a high relative density. In addition, the hydroxyl group in the binder reacts with the epoxy group of the epoxy resin to suppress the generation of water vapor, so the generation of bubbles can be suppressed, and the separator having a high relative density, high bending strength and low electric resistivity is formed. it can. If the separator can be formed with a low surface pressure, a small heating press and a mold can be used, so that an inexpensive fuel cell separator can be manufactured.

Further, if a curing accelerator is added as in Example 4, complete curing can be performed in the mold, so that heat treatment after molding is not necessary, equipment for the molding is unnecessary, and the production time of the separator is reduced. And cost can be reduced. As in Example 3, a phenol resin can be added as a binder together with bisphenols.

When the amount of the binder is 5 wt% or more, the separator as shown in FIG. 2 can be molded without a problem of strength. When the amount of the binder is 30 wt% or less, a separator having a practical range of electric resistivity can be used. Since it can be molded, the binder amount that can be practically used is determined to be 5 to 30% by weight.

[0074]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

[0075]

As described above, the present invention relates to a fuel cell separator characterized in that a mixture containing a carbon powder and a binder containing a bisphenol and an epoxy resin is hot-pressed in a mold having a predetermined shape. Since it is a fuel cell separator characterized by being manufactured using a manufacturing method and a method for manufacturing this fuel cell separator,
An inexpensive method for producing a fuel cell separator excellent in electric conductivity, gas impermeability, and strength, and a fuel cell separator can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic partial cross-sectional view showing an example of a fuel cell.

FIG. 2 is a front view of the separator 1C viewed from the oxidant electrode side.

FIG. 3 is a graph showing the relationship between the amount of binder added to carbon powder and the relative density.

FIG. 4 is a graph showing the relationship between the amount of binder added to carbon powder and the electrical resistivity.

FIG. 5 is a graph showing the relationship between the amount of binder added to carbon powder and bending strength.

[Explanation of symbols]

1A, 1B, 1C ... separator (separator for fuel cell)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01M 8/10 H01M 8/10 (72) Inventor Toshihisa Terasawa 2-1-1 Asahicho, Kariya City, Aichi Prefecture Aisin Within Seiki Co., Ltd. (72) Inventor Masami Ishii 5-50, Hachigen-cho, Kariya-shi, Aichi F-term in the Imura Materials Research Laboratory (reference) 4J002 CD001 CD061 DA027 DA037 EJ036 EN078 ER028 EU118 EV076 EV218 EV226 FD146 FD158 FD207 GQ00 4J036 AA01 AF06 AF07 DB05 DB06 DC31 DC40 DC44 FA02 JA15 5H026 AA06 BB01 BB02 BB08 CX07 EE05 EE18 HH05

Claims (6)

[Claims] 1. A method for producing a separator for a fuel cell, wherein a mixture containing a carbon powder and a binder containing a bisphenol and an epoxy resin is hot-press-molded in a mold having a predetermined shape. 2. The method for producing a fuel cell separator according to claim 1, wherein the binder contains a phenol resin. 3. The method for producing a fuel cell separator according to claim 2, wherein the content of the phenol resin is 70 wt% or less of the total amount of the binder. 4. The composition according to claim 1, wherein a ratio of a hydroxyl group contained in the binder to an epoxy group contained in the binder is 0.8.
The method for producing a fuel cell separator according to any one of claims 1 to 3, wherein: 5. The method for producing a fuel cell separator according to claim 1, wherein the mixture contains a curing accelerator for an epoxy resin. 6. A fuel cell separator manufactured by using the method for manufacturing a fuel cell separator according to claim 1. Description: