JP2001313045A - Fuel cell separator and manufacturing method of the same, and solid state macromolecular fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently mass-produce a fuel cell separator with high elasticity, good mold-releasing property, accuracy of dimension, and gas impermeability, and to obtain a highly efficient solid state macromolecular fuel cell which is not cracked at assembly and retains high gas sealing property and excellent impact resistance by using the fuel cell separator wholly or partially. SOLUTION: For the solid state macromolecular fuel cell and the manufacturing method of the fuel cell separator, the fuel cell is formed by shaping a compound for the fuel cell composed of a conductive material and a binding material as a principal element. A thermoplastic elastomer is used as the binder and 10-80 parts by mass of the thermoplastic elastomer is added against 100 parts by mass of the conductive material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell separator, a method for producing the same, and a polymer electrolyte fuel cell. More specifically, the present invention relates to a fuel cell having high elasticity, excellent releasability during molding, excellent dimensional accuracy, and excellent gas. Fuel cell separator having impermeability and method for producing the same, solid fuel cell having high gas sealability and excellent impact resistance using part or all of the fuel cell separator, and suitable as a power source for transportation of automobiles and the like The present invention relates to a molecular fuel cell.

[0002]

2. Description of the Related Art As shown in FIG. 1, a fuel cell, particularly a polymer electrolyte fuel cell, has a plurality of protrusions (ribs) 1a on both left and right sides.
Dozens to hundreds of single cells (unit cells) each including a single fuel cell separator 1, 1 and a solid polymer electrolyte membrane 2 and a gas diffusion electrode 3 interposed between the separators are provided. Battery main body (cell stack).

As shown in FIG. 2, the fuel cell separator 1 has a unique shape in which a plurality of projections (ribs) 1a are provided on both right and left sides of a thin plate-like body. The fuel cell separator is required to have high elasticity and excellent dimensional accuracy in order to form a flow path 4 for supplying and discharging fuel gas such as hydrogen and oxygen between the projection 1a of the separator and the electrode 3. In addition, the fuel cell separator and the unit cell (fuel cell) have a high gas sealing property that does not cause leakage of fuel gas, and the separator does not crack or crack when tightened with bolts and nuts when assembling the fuel cell. In particular, when used as a mobile power source for automobiles and the like, it is strongly desired to have excellent impact resistance.

For this reason, a fuel cell has been proposed in which an elastomer gasket is provided on the periphery of a unit cell to improve the sealing property and the ease of assembly (Japanese Patent Laid-Open No. 11-219).
714). Further, a fuel cell having improved gas sealing properties by applying and bonding a rubber-modified adhesive having an elastic modulus of 10 MPa or less to an adhesive surface between a separator and an electrolyte membrane has been proposed (JP-A-11-154522). Gazette). Furthermore, when sandwiching the pair of reactive electrodes between the pair of separator plates, a gasket sealing material made of a polyisobutylene-based polymer material was disposed in a space around the electrodes between the separator plates or in the electrode peripheral portion of the separator plate. A fuel cell has been proposed (JP-A-11-345620).

However, since the separator of the above-mentioned conventional fuel cell has low elasticity of the separator itself and has partial thickness unevenness and distortion, it is difficult to seal between the separator and the electrode or to use an elastomeric material. Even if a gasket is attached, sufficient gas sealing properties have not been obtained.
Further, there is a problem that cracks and cracks are generated in the separator due to tightening with bolts and nuts when assembling the fuel cell, and gas leakage occurs from these cracks and cracks.

On the other hand, a fuel cell has a low voltage that can be taken out per unit cell, and in order to obtain a battery output of a practical scale (up to several hundred kW), several tens to several hundreds of unit cells must be arranged in parallel. . For this reason, there is a strong demand for efficient mass production of fuel cell separators having a uniform shape without partial thickness unevenness or distortion.

However, conventional fuel cell separators mainly comprising a thermosetting resin such as a phenolic resin and graphite and graphite are poor in fluidity because a large amount of graphite is added to impart necessary conductivity. It is difficult to perform injection molding. For this reason, the fuel cell separator puts the compound into a separator molding die,
It is manufactured by hot-pressing at 14.7 to 29.4 MPa for 5 to 10 minutes. However, such a compression molding method requires a long molding time, is low in efficiency, and is not suitable for mass production. It is.

The present invention has been made in view of the above circumstances, and provides a fuel cell separator having high elasticity, excellent mold release properties during molding, excellent dimensional accuracy, and excellent gas impermeability, a method of manufacturing the same, and a fuel cell. An object of the present invention is to provide a polymer electrolyte fuel cell which has no cracks or cracks in a separator due to fastening during assembly, and has high gas sealing properties and excellent impact resistance.

[0009]

Means for Solving the Problems and Embodiments of the Invention The present inventor has conducted intensive studies on a binder used in a composition for a fuel cell separator in order to achieve the above object. It has been found that the use of an elastomer is effective in efficiently obtaining a fuel cell separator having high elasticity, excellent dimensional accuracy, and gas impermeability.

That is, in a fuel cell separator obtained by molding a composition for a fuel cell separator containing a conductive material and a binder as main components, a thermoplastic elastomer is used as the binder, and the thermoplastic elastomer is used as the conductive material. By adding 10 to 80 parts by mass with respect to parts by mass, J
A fuel cell separator having bending strength, flexural modulus, and strain in accordance with IS K6911 satisfying the following relational expression is obtained, and has high elasticity, excellent dimensional accuracy without partial thickness unevenness and distortion, and gas impermeability. A high-quality fuel cell separator is obtained, and when assembling a fuel cell using the fuel cell separator in part or in whole, the separator does not crack or crack even when tightened with bolts and nuts, and is high. Has gas sealing properties and excellent impact resistance,
The present inventors have found that a polymer electrolyte fuel cell which is most suitable as a power source for moving an automobile or the like can be obtained, and have accomplished the present invention. Flexural strength (MPa) / strain (mm) ≦ 10 Flexural modulus (GPa) / strain (mm) ≦ 3 20 ≦ Bending strength (MPa) × flexural modulus (GPa) ≦ 2
00

Further, according to the present invention, injection molding, which has been conventionally difficult, becomes possible by using a mixture obtained by adding 10 to 80 parts by mass of a thermoplastic elastomer to 100 parts by mass of a conductive material. It has a unique shape with a large number of protrusions (ribs) on both left and right sides of the body, enabling efficient and mass-production of thin fuel cell separators and cost reduction of products. You can do it.

Therefore, the present invention firstly provides a fuel cell separator obtained by molding a fuel cell separator composition containing a conductive material and a binder as main components, in accordance with JIS K6911 of the above fuel cell separator. A fuel cell separator characterized in that flexural strength, flexural modulus, and strain satisfy the following relational formula: flexural strength (MPa) / strain (mm) ≦ 10 flexural modulus (GPa) / strain (mm) ≦ 320 ≤ Bending strength (MPa) x Flexural modulus (GPa) ≤ 2
Secondly, in a fuel cell separator obtained by molding a fuel cell separator composition containing a conductive material and a binder as main components, a thermoplastic elastomer is used as the binder,
A fuel cell separator characterized in that 10 to 80 parts by mass of the thermoplastic elastomer is added to 100 parts by mass of a conductive material. Third, a composition for a fuel cell separator containing a conductive material and a binder as main components. In a method for producing a fuel cell separator, the injection molding is performed using a mixture obtained by adding and mixing 10 to 80 parts by mass of a thermoplastic elastomer with respect to 100 parts by mass of the conductive material. Manufacturing method, and fourthly, a structure in which a large number of unit cells including a pair of electrodes sandwiching a solid polymer electrolyte membrane and a pair of separators forming a gas supply / discharge flow path sandwiching the electrodes are arranged in parallel. Wherein the fuel cell separator is used as a part or all of all the separators in the fuel cell. To provide a molecular type fuel cell.

Hereinafter, the present invention will be described in more detail. The fuel cell separator of the present invention is obtained by molding a fuel cell separator composition containing a conductive material and a binder as main components, and the separator has the following flexural strength, flexural modulus, and strain in accordance with JIS K6911. It is characterized by satisfying the relational expression, whereby a fuel cell separator having high elasticity and excellent dimensional accuracy can be obtained, and there is no problem such as cracks or cracks in the separator due to tightening during assembly to the fuel cell. It is. Flexural strength (MPa) / strain (mm) ≦ 10 Flexural modulus (GPa) / strain (mm) ≦ 3 20 ≦ Bending strength (MPa) × flexural modulus (GPa) ≦ 2
00

Here, the fuel cell separator of the present invention comprises:
According to JIS K6911 "General Test Method for Thermosetting Plastics", 100%
A test piece of mm × 10 mm × 4 mm was prepared, and its bending strength, flexural modulus, and strain were measured. As a result, these satisfied the following relational expressions.

Bending strength (MPa) / strain (mm) ≦ 10
And preferably bending strength (MPa) / strain (mm)
≦ 7, more preferably bending strength (MPa) / strain (m
m) ≦ 5 , more preferably flexural strength (MPa) / strain (mm) ≦ 3. In this case, the lower limit is not particularly limited, but it is preferable that bending strength (MPa) / strain (mm) ≧ 1. Flexural modulus (GPa) / strain (mm) ≦
3, preferably flexural modulus (GPa) / strain (m
m) ≦ 2, more preferably flexural modulus (GPa) / strain (mm) ≦ 1, even more preferably flexural modulus (GPa) /
Strain (mm) ≦ 0.4. In this case, the lower limit is not particularly limited, but bending strength (MPa) / strain (mm) ≧
It is preferably 0.1. 20 ≦ Bending strength (MP
a) × flexural modulus (GPa) ≦ 200, preferably 50 ≦ flexural strength (MPa) × flexural modulus (GPa) ≦
150, more preferably 60 ≦ flexural strength (MPa) × flexural modulus (GPa) ≦ 110.

If the bending strength, the bending elastic modulus, and the strain of the fuel cell separator do not satisfy the above relational expressions, the elasticity of the separator becomes insufficient, and the separator is cracked or cracked by tightening bolts and nuts during assembly. Occurs. Further, the gas-sealing property of the polymer electrolyte fuel cell assembled by partially or entirely using the fuel cell separator is reduced, and the impact resistance is deteriorated, so that the polymer electrolyte fuel cell cannot be used as a power source for moving vehicles and the like.

The bending strength of the fuel cell separator of the present invention is preferably 20 to 80 MPa, more preferably 2 to 80 MPa.
5 to 60 MPa. Flexural modulus is preferably 1 to 1
It is 5 GPa, more preferably 2 to 10 GPa. The distortion is preferably 2 to 15 mm, more preferably 3 to 12 m
m.

Further, the fuel cell separator of the present invention
In accordance with the method B (equal pressure method) of “Evaluation Method of Gas Permeability of Plastic Film” of IS K 7126, a test piece having a thickness of 100 mm and a thickness of 100 mm was prepared from a composition for a fuel cell separator, and N ₂ gas permeation at 23 ° C. Degree (cm ³ / m ² · 24 hr
· Atm), the result was 20 cm ³ / m ² · 24 hr
Less than atm, preferably 10 cm ³ / m ² · 24
hr · atm or less, more preferably 5 cm ³ / m ² · 24
hr · atm or less. If the gas permeability is too large, gas leakage may occur from the fuel cell separator, and the object and effects of the present invention may not be achieved.

Such a fuel cell separator comprises (A)
It can be obtained by molding a fuel cell separator composition containing a conductive material and a binder (B) as main components.

Here, examples of the conductive material of the component (A) include carbon black, Ketjen black, acetylene black, carbon whiskers, graphite, metal fibers, and metal powders such as titanium oxide and ruthenium oxide. Can be used alone or in combination of two or more. Among these, graphite is particularly preferred.

In this case, the graphite may be naturally produced or artificially produced, and may be graphite having any shape such as a scale, a needle or a sphere. The average particle size of the graphite is preferably 1000 μm or less, more preferably 30 to 1000 μm, and still more preferably 50 to 500 μm. If the average particle size of the graphite is too small, the fluidity of the composition may decrease, and it may be difficult to perform injection molding. On the other hand, if the average particle size of graphite is too large, the mechanical strength of the formed separator may decrease.

Further, as the conductive material of the component (A) of the present invention, it is preferable to use graphite obtained by adding Ketjen black, acetylene black or a mixture thereof having excellent conductivity to graphite. The amount of Ketjen Black or acetylene black or a mixture thereof is preferably 1 to 30% by mass of the total amount of the conductive material.

As described above, in the case of using graphite mixed with Ketjen black or acetylene black or a mixture thereof as the conductive material, ketjen black or acetylene black or a mixture thereof is combined with the component (B) in advance. After sufficiently kneading with the material, it is preferable to add and mix graphite in order to further improve the conductivity.

As the binder of the component (B), a thermoplastic elastomer is used. As the thermoplastic elastomer, it is possible to use one kind selected from polystyrene-based elastomer, polyolefin-based elastomer, polyester-based elastomer, polyvinyl chloride-based elastomer, polyurethane-based elastomer and polyamide-based elastomer alone or in combination of two or more kinds. it can.

Such a thermoplastic elastomer basically has a structure in which a hard polymer component and a soft polymer component are combined, and is not particularly limited in structure, but has a softening point of 90 ° C. The above are preferred.

Specifically, polystyrene-based elastomers (hard component: polystyrene, soft components: polybutadiene, polyisoprene, hydrogenated polybutadiene), polyolefin-based elastomers (hard component: polypropylene, polyethylene, etc., soft components: ethylene-α-olefin) Rubber, butyl rubber, nitrile rubber, etc.), polyester elastomer (hard component: polyester, soft component: polyether), polyamide elastomer (hard component: polyamide, soft component: polyester, polyether), polyvinyl chloride elastomer (hard) Min: polyvinyl chloride, soft: plasticized polyvinyl chloride, nitrile rubber), polyurethane elastomer (hard: polyurethane, soft:
Polyester, polyether) and the like. Among these, polyurethane-based elastomers and polyolefin-based elastomers are preferred.

The amount of the thermoplastic elastomer (B) is 1 to 100 parts by mass of the conductive material (A).
0 to 80 parts by mass, preferably 20 to 70 parts by mass,
More preferably, it is 20 to 60 parts by mass. If the addition amount of the thermoplastic elastomer (B) is too small, the fluidity of the molding material (raw material mixture) becomes low, making injection molding difficult. On the other hand, if it is too large, the content of the conductive material is increased. And the conductivity is reduced, and the object of the present invention cannot be achieved.

In addition to the components (A) and (B), the composition for a fuel cell separator of the present invention may further comprise a fiber for the purpose of improving strength, releasability, hydrolysis resistance, conductivity and the like. A base material, a release agent, a metal powder, a hydrolysis-resistant agent and the like can be added as required.

Examples of the fiber base include metal fibers such as iron, copper, brass, bronze, and aluminum, ceramic fibers, potassium titanate fibers, glass fibers, carbon fibers, rock wool, wollastonite, sepiolite, attapulgite, Examples include inorganic fibers such as artificial mineral fibers, organic fibers such as aramid fibers, polyimide fibers, polyamide fibers, phenol fibers, cellulose, and acrylic fibers. These may be used alone or in combination of two or more. Can be. In this case, the compounding amount of the fiber base is 0 to 10 parts by mass with respect to 100 parts by mass of the conductive material (A).

The release agent is not particularly restricted but includes silicone release agents, fluorine release agents, fatty acid metal release agents,
Amide release agents, wax release agents and the like,
In particular, an internal release agent such as carnauba wax, stearic acid, montanic acid or the like is used. In this case, the compounding amount of the release agent is 0 to 3 parts by mass based on 100 parts by mass of the conductive material (A).

As the metal powder, stainless steel, gold, silver,
Copper, platinum, titanium, aluminum, nickel, or the like can be used. In this case, the average particle size of the metal powder is usually 5
３０30 μm.

Next, the method for producing a fuel cell separator according to the present invention is characterized in that the thermoplastic elastomer (B) is added in an amount of 10 to 80 parts by mass with respect to 0100 parts by mass of the conductive material (A). Injection molding is performed using a mixture obtained by adding and mixing a fiber base material, a release agent, a metal powder and the like.

In this case, as the molding material (raw material mixture), it is preferable to use pellets which have been pelletized using a kneading extruder in advance, which is a single-screw or twin-screw or a combination thereof. Further, a pulverized product obtained by pulverizing a cooled product after melt-kneading with a kneader or an extruder to a predetermined particle size can also be used.

Specific injection molding conditions include an injection molding machine,
Although it depends on the type and blending amount of the thermoplastic elastomer and cannot be specified unconditionally, the following is preferred. Cylinder temperature: 150 to 250 ° C Injection pressure: 80 to 190 MPa Injection time: 5 to 15 seconds Mold temperature: 20 to 80 ° C Curing time: 15 to 90 seconds

The fuel cell separator composition of the present invention can be formed not only by injection molding and extrusion molding but also by ordinary compression molding and transfer molding.

According to the production method of the present invention, the thin plate-shaped body has a peculiar shape having a large number of convex portions (ribs) on both right and left side surfaces and is thin, so that it has been difficult conventionally. Injection molding becomes possible, production efficiency is dramatically improved, and mass production becomes possible.

Next, the polymer electrolyte fuel cell of the present invention comprises:
The fuel cell has a structure in which a large number of unit cells each including a pair of electrodes sandwiching a solid polymer electrolyte membrane and a pair of separators forming a gas supply / discharge flow path sandwiching the electrodes are arranged in parallel. The fuel cell separator of the present invention is used as a middle separator.

In this case, the fuel cell of the present invention uses the above-mentioned high elasticity and excellent gas-impermeable fuel cell separator of the present invention as a part or all of the entire separator of the fuel cell. Specifically, 50% or more of all the separators in the fuel cell, preferably 50 to 100%, more preferably 70 to 100%, and still more preferably 80 to 100%.
% Is preferably the fuel cell separator of the present invention. If the ratio of the fuel cell separator of the present invention to all the separators in the fuel cell is too small, cracks and cracks occur in the separator due to tightening with bolts and nuts when assembling into the fuel cell, and the gas sealability and impact resistance deteriorate. However, in some cases, the objects and effects of the present invention cannot be achieved. In addition, as a separator other than the fuel cell separator of the present invention, a separator commonly used in a fuel cell can be used.

Here, as the solid polymer electrolyte membrane, those commonly used in polymer electrolyte fuel cells can be used. For example, polytrifluorostyrenesulfonic acid, perfluorocarbonsulfonic acid (trade name: Nafion), which is a proton-conductive ion exchange membrane formed of a fluororesin, and the like can be used. On the surface of the electrolyte membrane, a carbon powder supporting platinum as a catalyst or an alloy composed of platinum and another metal is prepared, and the carbon powder supporting the catalyst is mixed with a lower fatty acid alcohol containing perfluorocarbonsulfonic acid and water. Is applied to a paste dispersed in an organic solvent such as a mixed solution (Nafion 117 solution).

The pair of electrodes sandwiching the solid polymer electrolyte membrane can be formed of carbon paper, carbon felt, carbon cloth woven with a thread made of carbon fiber, or the like.

The electrolyte membrane and the electrodes are integrated by interposing an electrolyte membrane between a pair of electrodes and thermocompression bonding at 120 to 130 ° C. Note that the electrolyte membrane and the pair of electrodes can be joined and integrated using an adhesive.

The united cell is obtained by mounting the integrated electrolyte membrane and electrode in such a manner as to form a flow path through which fuel gas can be supplied and discharged between a pair of separators. In this case, a portion (rib) in contact with the electrode of the separator
A method of applying an adhesive to the substrate and attaching the same can be adopted.

The polymer electrolyte fuel cell according to the present invention has high elasticity and excellent gas impermeability as a part (preferably 50% or more) of all the separators in the fuel cell. By using a separator,
Since the separator does not crack or crack due to tightening during assembly, and has high gas sealing properties and excellent impact resistance, it is particularly suitable as a power source for moving automobiles, small boats and the like.

The polymer electrolyte fuel cell according to the present invention
In addition to mobile power sources for automobiles and small ships, it can be widely used for various purposes such as small-scale local power generation, home power generation, simple power sources for campsites, artificial satellites, and space development power sources. .

[0045]

According to the present invention, a fuel cell separator having high elasticity, excellent releasability, dimensional accuracy, and gas impermeability can be efficiently mass-produced, and a part or all of the fuel cell separator can be manufactured. By using this, a high-performance polymer electrolyte fuel cell which has no cracks or cracks during assembly and has high gas sealing properties and excellent impact resistance can be obtained.

[0046]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In addition, the compounding quantity of each component in Table 1 is all parts by mass.

Examples 1 to 6 and Comparative Examples 1 to 4 The compositions shown in Table 1 were kneaded using a twin-screw kneading extruder (Berstorf ZE40A segment type) and pelletized. The obtained pellets were subjected to injection molding using an injection molding machine (manufactured by Sumitomo Heavy Industries) under the following conditions to obtain a length of 120 mm and a width of 120 m.
m, a fuel cell separator having a thickness of 2.3 mm and having protrusions on both left and right sides as shown in FIG. 2 was prepared. <Molding conditions> Cylinder temperature: 150 to 250 ° C Injection pressure: 180 MPa Injection time: 5 to 15 seconds Mold temperature: 50 to 60 ° C Curing time: 15 to 90 seconds

The resulting separator was evaluated for moldability, release property, dimensional stability, gas permeability, and assemblability according to the following criteria. Table 1 shows the results. Moldability ：: good △: slightly poor ×: poor mold release ○: good △: slightly poor ×: poor dimensional stability ○: good △: slightly poor ×: poor gas permeability JIS K 7126 “Plastic film gas” N ₂ gas permeability (cm ³ / m ² · 24 hr · at) at 23 ° C. of a 2 mm-thick φ100 test piece cut out from a separator according to Method B (equal pressure method) of “Permeability Evaluation Method”.
m) was measured and evaluated according to the following criteria. ：: less than 20 △: 20 to 10 ³ ×: more than 10 ³ assemblability When two sets of the obtained separators were made into one set, 50 sets were arranged side by side and tightened with a bolt and a nut at a pressure of 44 to 59 MPa. Of the separator and the occurrence of cracks were evaluated according to the following criteria. ：: no cracks and cracks generated △: slight cracks generated ×: cracks and cracks generated

Next, the compositions shown in Table 1 were injection molded under the same conditions as above to prepare test pieces of 100 mm × 10 mm × 4 mm. The bending strength, flexural modulus, strain and specific resistance of the obtained test piece were measured by the following methods. Table 1 shows the results. Flexural strength, flexural modulus, and strain Measured according to a general test method for thermosetting plastics according to JIS K6911. Specific Resistance The specific resistance was measured according to the resistivity measurement method of a silicon single crystal and a silicon wafer according to JIS H0602 by a four probe method.

[0050]

[Table 1] * 1: Graphite (flaky graphite, average particle size 50 μm, BF80A manufactured by Chuetsu Graphite Industry Co., Ltd.) * 2: Ketjen Black (Lion Corporation, trade name: Ketjen Black EC) * 3: Elastomer A; polyurethane Elastomer (Dainichi Seika Kogyo Co., Ltd., trade name Rezamin EC-51)
0) * 4: Elastomer B; polyolefin-based elastomer (trade name: Mirastomer 5030, manufactured by Mitsui Chemicals, Inc.)
N) * 5: Phenol resin trade name XPGA6525B (softening point 60-70 ° C, manufactured by Gunei Chemical Industry Co., Ltd.) * 6: Zinc stearate

Example 7 Solid Polymer Fuel Cell (1) Carbon paper (manufactured by Chemics Co., Ltd.) was used as a pair of electrodes sandwiching a solid polymer electrolyte membrane (trade name: Nafion). These were joined by an ordinary method to form an integrated electrode. A unit cell having a fuel gas supply / discharge flow path was obtained by sandwiching the integrated electrode between the pair of fuel cell separators prepared in Example 1. A fuel cell was assembled by arranging 50 unit cells side by side and fastening them with bolts and nuts. At this time, cracks and cracks did not occur on the separator by tightening with the bolts and nuts. The obtained fuel cell was chargeable and dischargeable, and was found to function effectively as a fuel cell. Example 8 Polymer Electrolyte Fuel Cell (2) Carbon paper (manufactured by Chemics Co., Ltd.) was used as a pair of electrodes sandwiching a polymer electrolyte membrane (trade name: Nafion). These were joined by an ordinary method to form an integrated electrode. A unit cell having a fuel gas supply / discharge flow path was obtained by sandwiching the integrated electrode between the pair of fuel cell separators prepared in Example 3. A fuel cell was assembled by arranging 100 unit cells side by side and fastening them with bolts and nuts. At this time, cracks and cracks did not occur on the separator by tightening with the bolts and nuts. The obtained fuel cell was chargeable and dischargeable, and was found to function effectively as a fuel cell. Example 9 Solid Polymer Fuel Cell (3) Carbon paper (manufactured by Chemics Co., Ltd.) was used as a pair of electrodes sandwiching a solid polymer electrolyte membrane (trade name: Nafion). These were joined by an ordinary method to form an integrated electrode. A unit cell having a fuel gas supply / discharge flow path was obtained by sandwiching the integrated electrode between the pair of fuel cell separators prepared in Example 6. A fuel cell was assembled by arranging 100 unit cells side by side and fastening them with bolts and nuts. At this time, cracks and cracks did not occur in the separator by tightening with the bolts and nuts. The obtained fuel cell was chargeable and dischargeable, and was found to function effectively as a fuel cell.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a fuel cell.

FIG. 2 is a perspective view of a fuel cell separator according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Separator 1a Rib 2 Solid polymer electrolyte membrane 3 Gas diffusion electrode 4 Flow path

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Atsushi Miyazawa 1-2-3, Onodai, Midori-ku, Chiba-shi, Chiba Prefecture F-term in the R & D Center 5N026 AA06 BB01 BB02 BB08 CC03 EE18 HH00 HH05

Claims (6)

[Claims] 1. A fuel cell separator obtained by molding a composition for a fuel cell separator containing a conductive material and a binder as main components, wherein the fuel cell separator is JIS K69.
11. A fuel cell separator, wherein the flexural strength, flexural modulus and strain according to No. 11 satisfy the following relational expressions. Flexural strength (MPa) / strain (mm) ≦ 10 Flexural modulus (GPa) / strain (mm) ≦ 3 20 ≦ Bending strength (MPa) × flexural modulus (GPa) ≦ 2
00 2. A fuel cell separator formed by molding a composition for a fuel cell separator containing a conductive material and a binder as main components, wherein a thermoplastic elastomer is used as the binder, and the thermoplastic elastomer is used as a conductive material. A fuel cell separator, wherein 10 to 80 parts by mass is added to parts by mass. 3. The method according to claim 1, wherein the thermoplastic elastomer is a polystyrene elastomer, a polyolefin elastomer,
The fuel cell separator according to claim 2, wherein the fuel cell separator is at least one member selected from the group consisting of a polyester elastomer, a polyvinyl chloride elastomer, a polyurethane elastomer, and a polyamide elastomer. 4. A fuel cell separator obtained by molding a composition for a fuel cell separator containing a conductive material and a binder as main components, wherein the separator has a flexural strength, a flexural modulus and a strain in accordance with JIS K6911. 4. The fuel cell separator according to claim 2, wherein the following relational expression is satisfied. Flexural strength (MPa) / strain (mm) ≦ 10 Flexural modulus (GPa) / strain (mm) ≦ 3 20 ≦ Bending strength (MPa) × flexural modulus (GPa) ≦ 2
00 5. A method for producing a fuel cell separator obtained by molding a composition for a fuel cell separator containing a conductive material and a binder as main components, wherein a thermoplastic elastomer is added to 100 parts by mass of the conductive material. A method for producing a fuel cell separator, comprising injection-molding a mixture obtained by adding and mixing 80 parts by mass. 6. A solid having a structure in which a large number of unit cells each comprising a pair of electrodes sandwiching a solid polymer electrolyte membrane and a pair of separators forming a gas supply / discharge flow path sandwiching said electrodes are provided. A polymer electrolyte fuel cell, wherein the fuel cell separator according to any one of claims 1 to 4 is used as a part or all of all the separators in the fuel cell.