JP2002231263A - Separator of fuel cell and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator used for a solid high polymer membrane type fuel cell, excellent in such performance as electric conductivity, gas permeability, mechanical strength and the like, and also to provide an industrially advantageous method for manufacturing such separators. SOLUTION: This separator having a gas permeable groove is used for the solid high polymer membrane type fuel cell. The separator is typically manufactured by a vacuum compression molding method, and all of the following conditions are satisfied when manufacturing the separator; (a) the separator is a molding molded from a composition of graphite and fluororesin, and the graphite forms a filler and the fluororesin forms a matrix, (b) when the rate of the graphite contained in the total quantity of the graphite and the fluororesin in the composition is set for G, and the rate of the fluororesin is set for F, G is 60-95 wt.% and F is 40-5 wt.%, and (c) the density of the molding is not less than 1.8 g/cm3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer electrolyte membrane fuel cell separator and a method for manufacturing the separator.

[0002]

2. Description of the Related Art Various types of fuel cells are proposed, including a phosphoric acid type, a molten carbonate type, a solid electrolyte type (solid oxide type), and a solid polymer membrane type (solid polymer type). Have been. Among them, a solid polymer membrane type, which has a low operating temperature of 80 ° C. or less and a short startup time of several seconds, and is therefore expected to be put to practical use as a future electric vehicle or home power supply, has attracted particular attention.

[0003] This solid polymer membrane fuel cell is basically composed of "water cooling plate / water permeable plate / separator / gas diffusion layer / catalyst layer / polymer membrane / catalyst layer / gas diffusion layer / separator". The left "gas diffusion layer / catalyst layer" functions as an anode, and the right "gas diffusion layer / catalyst layer" functions as a cathode. Since a fluorine-based solid polymer membrane is usually used as the electrolyte, it is called a solid polymer membrane fuel cell.

In the above, the separator is composed of fuel (hydrogen)
And a conductive member having a gas flow path for supplying air and having a rib (groove).

(A) A typical polymer electrolyte membrane fuel cell separator is formed by molding a carbonaceous powder such as graphite using a thermosetting resin such as a phenolic resin as a binder, and heat-curing the molded product. And many applications have been filed. Some of them are listed below. Patent Document 1: JP-A-2000-77079 A solid polymer electrolyte type composed of a composite formed by binding graphite powder with a thermosetting resin, wherein the composite has a graphite powder content of 85 to 97% and a thermosetting property. Resin having a composition ratio of 3 to 15%. Patent Document 1: JP-A-2000-40517 Artificial graphite powder and natural graphite powder in a weight ratio of 80:20 to 2
100 parts by weight of graphite powder mixed at a ratio of 0:80;
A carbonaceous separator member for a polymer electrolyte fuel cell, comprising 10 to 25 parts by weight of a thermosetting resin. Patent Document 1: JP-A-11-204120 A method for producing a fuel cell separator in which a raw material containing carbon and a binder, the raw material containing an epoxy resin and a phenol resin as a binder is hot-press molded in a predetermined mold.

Although it does not relate to a solid polymer film type,
Some proposals have also been made for a fuel cell separator obtained by solidifying graphite with a fluororesin.

(B) JP-A-61-69853 discloses that a conductive filler, a fluorine-containing polymer, a particle size of 10
μm or less polytetrafluoroethylene fine particles 5 to 30
The figure shows a conductive resin composition to which a weight% is added. It is described that the proportions of the conductive filler and the fluoropolymer are preferably 10 to 60% by weight and 30 to 85% by weight, respectively. As the fluorine-containing polymer, P
It is stated that TFE, polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, fluorine-containing epoxy resin, fluorine-containing silicone resin, and the like are used. As a molding method, extrusion molding, calender molding, injection molding and the like can be used in addition to compression molding.

In Examples, graphite having an average particle diameter of 10 μm was used as a conductive filler, PTFE molding powder having an average particle diameter of 25 μm was used as a fluorine-containing polymer, and polytetrafluoroethylene fine particles having an average particle diameter of 7 μm were used. Using a PTFE wax, these raw materials are mixed by a ball mill to form a molding powder, and then the powder is uniformly filled in a mold, and then pressed at room temperature to form a preform. Was placed in a heating furnace while being sandwiched between metal plates, heated to 370 ° C. and maintained at this temperature for a predetermined time, and then cooled to complete firing, thereby obtaining a disk-shaped molded body sample.

This publication also states that the resin composition of the present invention is suitable for use in a separate plate of a fuel cell and the like.

(C) Japanese Patent Application Laid-Open No. 57-107570 relates to an invention assuming a fuel cell using phosphoric acid as an electrolyte. The separator is formed of a mixture of a fluorine-based resin and graphite. A fuel cell is shown. A typical example of the fluororesin is an ethylene tetrafluoride polymer (that is, polytetrafluoroethylene, PT
FE), a fluorinated ethylene-propylene copolymer (that is, F
EP). The graphite content is 50-75% by weight. In the example, 330 ° C. × 30 kg / cm ² ×
A sheet having a thickness of 0.6 mm is manufactured by heating and pressing under a condition of 10 minutes.

[0011]

As described in (a) above,
As a typical separator of a polymer electrolyte fuel cell, a separator obtained by molding a carbonaceous powder such as graphite with a thermosetting resin such as a phenol resin as a binder and heating and curing the same is used. Since it is essential to cure the thermosetting resin after molding, it takes a long time to cure, and it is necessary to bake at a temperature of 800 ° C. or higher to make the thermosetting resin conductive. It takes time and money, the dimensions may change and the shape may be distorted at that time, and hundreds of cells are stacked for each fuel cell. There is a risk of cracking. ・ When using phenolic resin, the working environment is bad because formalin is inevitably volatilized in the atmosphere. There are problems such as, productivity, cost, quality, and has a problem of practical application in terms of the working environment.

In the conductive resin composition (b), the conductive filler and the fluoropolymer are added in an amount of 95 to 70% by weight based on 5 to 30% by weight of polytetrafluoroethylene fine particles having a particle diameter of 10 μm or less. And the proportions of the conductive filler and the fluoropolymer are 10% each.
Since the content of the conductive filler in the composition is at most 60% by weight, the content of the conductive filler is not more than 60% by weight. , Graphite (graphite) as conductive filler
However, there is a problem that conductivity is insufficient as a separator of a solid polymer membrane type fuel cell even when the fuel cell is used.

According to the study of the present inventors, even if the ratio of the conductive filler in the conductive resin composition of this publication is increased beyond the above upper limit, the fuel cell of the solid polymer membrane type is Even when the ribbed separator was obtained by a compression molding method, it was found that gas permeability and mechanical strength were essentially insufficient when used as a separator.

The separator in the above (c) relates to the invention assuming a fuel cell using phosphoric acid as an electrolyte. Even if a mixture with graphite is compression-molded to obtain a ribbed separator for a solid polymer membrane fuel cell, gas permeability, mechanical strength, and electrical conductivity may still be insufficient when used as a separator. found.

Under such circumstances, the present invention provides a separator having excellent properties such as electric conductivity, gas permeability and mechanical strength for use in a solid polymer membrane fuel cell, and It is an object of the present invention to provide an industrially advantageous production method of such a separator.

[0016]

The fuel cell separator of the present invention is a separator having a gas permeable groove for use in a solid polymer membrane type fuel cell, the separator comprising (a) graphite and fluorine. A molded article formed from a composition of a resin, wherein graphite is a filler, and a fluorine resin forms a matrix; (b) graphite in the total amount of graphite and fluorine resin in the composition; When the ratio is G and the ratio of the fluororesin is F, G is 60 to 9
At 5% by weight, F is 40-5% by weight; and
(C) The molded article satisfies all the conditions that the density D of the compact is 1.8 g / cm ³ or more.

The method of manufacturing a separator for a fuel cell according to the present invention is a method of manufacturing a separator having a gas permeable groove for use in a solid polymer membrane type fuel cell. When the total amount of the two is 100% by weight, a composition mixed so that the former ratio G is 60 to 95% by weight and the latter ratio F is 40 to 5% by weight,
Compression molded under vacuum conditions at higher than the melting point of the fluorine-based resin temperature, and characterized in that the graphite is obtained filler, the density 1.8 g / cm ³ or more shaped bodies fluororesin forms a matrix Is what you do.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

<< Separator >><Separator having gas permeable groove> The separator of the present invention is a separator having a gas permeable groove for use in a solid polymer membrane type fuel cell. As described in the section of the prior art, the polymer electrolyte membrane fuel cell is basically
It has the structure of “water cooling plate / water permeable plate / separator / gas diffusion layer / catalyst layer / polymer membrane / catalyst layer / gas diffusion layer / separator”, and the “gas diffusion layer / catalyst layer” on the left is the anode ,
The “gas diffusion layer / catalyst layer” on the right plays the role of cathode. As the electrolyte, for example, a fluorine-based solid polymer membrane is used. The separator is made of a conductive member having a gas flow path for supplying fuel (hydrogen) and air, and has a structure having a gas permeable groove.

The solid polymer membrane fuel cell may be a single cell or may have a stack structure in which single cells are stacked. Depending on whether the separator has a single cell or a stacked structure, it is determined whether the gas permeable groove of the separator is provided on one side or both sides (that is, one groove or both grooves). The wall part (rib) of the gas permeable groove is
It may have a taper.

<Molded Body Constituting Separator / Conditions (A)> In the present invention, the separator comprises:
It consists of a molded article molded from a composition of graphite and a fluororesin. In this molded body, graphite forms a filler, and a fluororesin forms a matrix.

(Graphite) As the graphite (ie, graphite), natural graphite, flaky artificial graphite (including quiche graphite, pyrolytic graphite, etc.), expanded graphite and the like are used, and natural graphite and flaky artificial graphite are particularly important. It is. In some cases, coke or artificial graphite other than flaky artificial graphite is mixed.
Incidentally, carbon materials other than flaky graphite also have a certain degree of suitability, but do not provide the same performance as graphite described above.

The average particle size of graphite is usually 5 to 200 μm.
About 10 to 80 μm, especially about 15 to 60 μm.
About μm is appropriate. When the average particle diameter is too small, a resin-rich state occurs, and the properties of the molded article tend to vary.On the other hand, when the average particle diameter is too large, the matrix resin sufficiently functions as a binder. Tends to fail.

(Fluorine Resin) As the fluorine resin,
Polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA),
Tetrafluoroethylene-hexafluoropropylene copolymer (FEP) is preferably used, and the first three are particularly important. In addition, ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polychlorotrifluoroethylene (PCTFE), polyvinyl fluoride (PVF) and the like can be used. Fluorocarbon resin is
Two or more kinds may be used in combination. It should be noted that thermoplastic resins other than fluorine resins, for example, thermoplastic resins such as ABS resin, polycarbonate, polyphenylene oxide, polyacetal, polyamide, and polyphenylene sulfide are fluorine-based in terms of chemical resistance, heat resistance, and water absorption. Inferior to resin.

The particle size of the fluororesin is arbitrary. When the fluororesin is used in the form of a solution, the particle size does not matter, of course.

<Blending Ratio and Conditions (B)> The ratio of each component in the graphite and fluororesin composition is set as follows. That is, when the ratio of graphite to the total amount of graphite and fluororesin in the composition is G, and the ratio of fluororesin is F, G is 60 to 95% by weight and F is 40 to 95% by weight.
5% by weight. When G is smaller than this range (when F is larger than this range), the conductivity becomes insufficient. When G is larger than this range (when F is smaller than this range), the strength of the obtained molded body becomes insufficient. A more preferred range is that G is 75-90% by weight and F
Is 25 to 10% by weight.

In addition to graphite and fluorine resin,
If it is a small amount (about 10% by weight or less of the whole) which does not impair the purpose of the present invention, conductive materials such as carbon (carbon particles, carbon fibers, etc.) other than graphite, metal (metal particles, metal fibers, etc.), polyacetylene Sexual substances can also be used in combination.

<Density of molded article / condition (c)> The density D of the molded article is set to 1.8 g / cm ³ or more. A more preferred range is 1.85 g / cm ³ or more. When the density D is less than 1.8 g / cm ³ , the performance as a separator having a gas permeable groove for use in a fuel cell is inferior in terms of electric conductivity, gas permeability, mechanical strength, and the like. The higher the density D, the better, but in practice, the upper limit is often up to about 2.5 g / cm ³ .

It is generally difficult to obtain a molded product having such a density range by a usual simple compression molding method. According to the vacuum compression molding method described below, a compact of 1.8 g / cm ³ or more can be obtained.
Corresponding conditions (type of graphite and fluorine resin,
The relationship with the density (reference density) d of a molded product obtained by molding by a general simple compression molding method under the same conditions of the compounding ratio, molding temperature and molding pressure is D ≧ 1.05d, preferably D ≧ 1.05 1.
10d, especially D ≧ 1.15d.

Therefore, in the present invention, as described below, a special method of performing compression molding under vacuum is adopted.

<< Method of Manufacturing Separator >> The ribbed separator of the present invention which satisfies all of the above conditions (a), (b) and (c) comprises a graphite powder and a fluororesin in a total amount of both. Is 100% by weight, the ratio G of the former is 6
0 to 95% by weight, and the latter is compression-molded under vacuum conditions at a temperature higher than the melting point of the fluororesin (that is, vacuum compression). Molding).
In the obtained molded body, graphite forms a filler, and a fluororesin forms a matrix.

The mixture of the graphite powder and the fluororesin may be a mixture of the powders.
A method of preparing a dispersion or solution of a fluororesin, mixing it with graphite powder, removing volatiles to form particles, and supplying the particles to a mold is employed.

As the mold, a mold having a recess having a predetermined shape is used in order to obtain a molded body having a gas permeable groove. In the case of a single groove, a mold having irregularities in one of the upper and lower molds (usually the upper mold) is used. In the case of both grooves, a mold having irregularities on both upper and lower molds is used. The mold has a structure that can be heated by any method. The mold is provided with micro holes for vacuum suction.

As a pressing method in vacuum compression molding,
A mechanism using mechanical pressurization, hydraulic pressure, pneumatic pressure, or water pressure is employed. The molding time required for vacuum compression molding is from about one minute to several tens of minutes, and is extremely short even if the following cooling time is included.

After the vacuum compression molding, the compact is cooled while it is between the molds. As the cooling method, for example, an appropriate method such as a method of flowing water through a mold, a method of putting the mold into water, a method of placing the mold in a cooling chamber, and a method of air-cooling the mold are adopted.

Typical conditions for vacuum compression molding are as follows. Temperature conditions The temperature is set to a temperature higher than the melting point of the fluororesin used, particularly to a temperature higher than the melting point by 5 ° C. or more, more preferably 10 ° C. or more, especially 20 ° C. or more. When two or more fluororesins having different melting points are used in combination, the temperature is set to a temperature at which most, especially all, of them are melted. Pressure conditions 50 kg / cm ² or more, preferably 100 kg / cm ² or more, especially 1
50 kg / cm ² or more is suitable, and the upper limit is up to about 1000 kg / cm ² . Usually, the pressure condition is set to about 100 to 400 kg / cm ² .・ Vacuum condition The mold is connected to a vacuum suction system and compared to atmospheric pressure, usually 16
0 Torr or less (-600 mmHg or less), preferably 60 Torr or less (-700 mmHg or less),
Further, the pressure is reduced to 30 Torr or less (a reduced pressure of -730 mmHg or more).

The thickness of the thus obtained molded body is
The total thickness is often about 0.9 to 2.5 mm, especially about 1 to 1.5 mm. The depth of the gas permeable groove is
It is often about 1/6 to 1 / 2.4, especially about 1/4 to 1/3 (in absolute thickness, about 0.2 to 0.5 mm, especially about 0.3 to 0.4 mm). However, it is not necessarily limited to these ranges.

[0038]

The present invention will be further described with reference to the following examples. Hereinafter, "parts" means parts by weight.

<Production of Separator> Example 1 FIG. 1 is a process chart showing an example of a method for producing a separator of the present invention. FIG. 2 is an explanatory diagram showing a state of compression molding under vacuum conditions. FIG. 3 is a cut end view showing an example of the shape of the separator of the present invention.

In FIG. 1, (1) is a mold having a built-in heating means (not shown), a lower mold (11), an upper mold (12), and a side mold.
It consists of (13) and (13). Both the lower mold (11) and the upper mold (12)
A concave portion (14) for forming a rib is provided, and a minute hole (not shown) is provided, so that a vacuum system (vac) can be used to reduce the pressure between the molds (11) and (12). I can do it.

A separator was manufactured according to the process shown in FIG. That is, first, 80 parts of graphite (flaky natural graphite, average particle diameter of 60 μm) and a dispersion of a fluororesin (polytetrafluoroethylene (PTFE),
E, melting point 327 ° C., average particle size of the PTFE 0.1 to 0.2
μm) and 20 parts (as PTFE), and then dried to remove volatile components. Thereby, the average particle diameter is 2
A granulated powdery composition having a particle size of 00 to 300 μm was obtained.

The obtained mixed powder was dropped from a sieve to uniformly fill a lower mold (11) which had been preheated. Next, lower the upper mold (12) and lower both molds (11), (1
By vacuum suction through the micro holes provided in 2), 1
While maintaining the reduced pressure condition of 0 Torr (−750 mmHg), the mold temperature was set to 395 ° C., and hot pressing was performed at a pressure of 200 kg / cm ^{2 for} 1 minute (see FIG. 2). After performing the vacuum compression molding, the mold (1) was put into a cooling device and cooled to room temperature. In FIG. 2, (2) is a forming raw material.

As a result, a molded product (separator) shown in FIG. 3 was obtained. The thickness of the molded body including the ribs was 1.35 mm, and the depth of the groove between the ribs was 0.4 mm. In FIG. 3, (3) is a molded body, (31) is a rib, and (32) is a gas flow passage.

Comparative Example 1 A mold temperature of 395 ° C. and a pressure of 20 were applied without performing vacuum suction.
Example 1 was repeated except that hot pressing was performed at 0 kg / cm ^{2 for} 10 minutes to obtain a molded body having a thickness of 1.55 mm.

Example 2 80 parts of graphite (flaky natural graphite, average particle diameter 60 μm) and a fluorine resin (polyvinylidene fluoride (PVD)
F) N-methylpyrrolidone solution, melting point 1 of the PVDF
(77 ° C.) and 20 parts (as PVDF), and then dried to remove volatile components.

Thereafter, vacuum compression molding was performed in the same manner as in Example 1 to obtain a molded body having a thickness of 1.30 mm (including the rib portion). However, the mold temperature is 230 ° C and the pressure is 200kg / c
m ² , and the hot press time was 1 minute.

Comparative Example 2 The mold temperature was 230 ° C. and the pressure was 20 without vacuum suction.
Example 2 was repeated except that hot pressing was performed under the conditions of 0 kg / cm ² and hot pressing time of 10 minutes to obtain a molded product having a thickness of 1.38 mm (including the rib portion).

Example 3 80 parts of graphite (flaky natural graphite, average particle size 60 μm) and a fluororesin (tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (TH)
V) Ethyl acetate solution, THV melting point 120 ° C) 20
And then dried to remove volatiles.

Thereafter, vacuum compression molding was performed in the same manner as in Example 1 to obtain a molded body having a thickness of 1.29 mm (including the rib portion). However, the mold temperature is 150 ° C and the pressure is 200kg / c
m ² , and the hot press time was 1 minute.

Comparative Example 3 A mold temperature of 150 ° C. and a pressure of 20 were applied without performing vacuum suction.
Example 3 was repeated except that hot pressing was performed under the conditions of 0 kg / cm ² and hot pressing time of 10 minutes to obtain a molded product having a thickness of 1.38 mm (including the rib portion).

<Evaluation of separator> The properties and physical properties of the molded articles obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were measured.
The suitability of the molded article as a ribbed separator in a solid polymer membrane fuel cell was examined.

The density was measured according to the underwater substitution method described in JIS K 7112. That is, a test piece suspended by a metal wire is weighed in the air, and then the test piece suspended by the metal wire is immersed in distilled water to remove bubbles and the like, and the mass is measured, and the density is calculated by the following formula. Calculated from Density = [a / (ab)] x _ρwt a: Mass of test specimen in air (g) b: Mass of test specimen measured in immersion liquid (g) _ρwt : Distillation of temperature t Water density

Regarding the electric conductivity, the volume resistivity was measured at three places at equal intervals from the center of a 100 mmφ test piece by a four-probe method using a low resistivity meter.

Regarding the gas permeability, a test piece having a permeation area of 30 mm × 70 mm was prepared, the test piece was sandwiched between SUS plate jigs, and the permeated hydrogen gas was measured for gas permeation concentration by gas chromatography. The hydrogen gas permeability was calculated from the equation. H = [H ₂ transmission amount (cm ³ ) × sample thickness (cm)] / [transmission area
(cm ² ) x differential pressure (atm) x time (sec)]

Table 1 shows the production conditions of the molded article and the evaluation results of suitability as a separator. Example 1 and Comparative Example 1,
Example 2 and Comparative Example 2 and Example 3 and Comparative Example 3 have a relationship corresponding to each other.

[0056]

[Table 1] Example Comparative Example Example Comparative Example Example Comparative Example 1 1 2 2 3 3 Matrix PTFE PTFE PVDF PVDF THV THV S M type Graphite: M 80:20 80:20 80:20 80:20 80:20 80:20 Composition ratio normal pressure / vacuum vacuum normal pressure vacuum normal pressure vacuum normal pressure compression molding pressure 200 200 200 200 200 200 (kg / cm ² ) Density 1.89 1.51 2.07 1.67 2.06 1.62 (g / cm ³ ) Electrical resistivity 1.2 4.7 3.3 3.8 10 12 (mΩ ・ cm) Gas permeability 1.1 38 0.7 24 2.5 62 (cm ² / sec) × 10 ^-4 × 10 ^-4 × 10 ^-4 × 10 ^-4 × 10 ^-4 × 10 ^-4 Flexural strength 34.5 1.2 38.5 0.9 27.9 1.1 (MPa)

From Table 1, the ratio D / d of the density D of the example which is a vacuum compression-molded product to the density (reference density) d of the corresponding comparative example which is a normal-pressure compression-molded product is shown. D / d = 1.89 / 1.51 = 1.25 in the comparison between Comparative Example 1 and Comparative Example 1, and D / d = 2.07 / 1.67 = 1.24 in the comparison between Example 2 and Comparative Example 2. D / d = 2.06 / 1.62 = 1.27.

Each of the examples has a lower electric resistivity (higher electric conductivity), a lower hydrogen gas permeability, a higher bending strength, and a superior fuel cell performance as compared with the corresponding comparative example. You can see that there is.

[0059]

According to the separator (molded product) of the present invention molded by a vacuum compression molding method from a composition of graphite and a fluororesin in a specific ratio, the density D of the molded product is 1.8 g / cm ^3.
As described above, it has a dense structure as compared with the density (reference density) d of the molded body obtained by the corresponding ordinary simple compression molding method.

This molded article has a small electric resistivity, a small gas (hydrogen) permeability, a large mechanical strength such as a bending strength, and has excellent performance as a fuel cell. Therefore,
Fuel cell performance is improving.

Further, when the separator of the present invention comprising the above-mentioned molded body is compared with a conventional typical separator using a thermosetting resin such as a phenol resin as a binder, no curing is required, so that the molding time is reduced. It is preferable in terms of working environment because it is greatly shortened and does not generate gas during vacuum compression molding. In addition, the present invention has an advantage that the molded body does not adhere to the mold during the molding operation, so that the mold need not be subjected to a mold release treatment.

Thus, the present invention is useful in terms of both performance and productivity as a ribbed separator used in a polymer electrolyte fuel cell.

[Brief description of the drawings]

FIG. 1 is a process chart showing an example of a method for producing a separator of the present invention.

FIG. 2 is an explanatory diagram showing a state of compression molding under vacuum conditions.

FIG. 3 is a cut end view showing an example of the shape of the separator of the present invention.

[Explanation of symbols]

(1) ... mold, (11) ... lower mold, (12) ... upper mold, (13) ... side mold, (14) ... recess, (2) ... molding raw material, (3) ... molded body, ( 31)
… Rib, (32)… Gas flow passage, (vac)… Vacuum system

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 27/12 C08L 27/12 H01M 8/10 H01M 8/10 // B29K 27:12 B29K 27:12 27 : 18 27:18 105: 16 105: 16 507: 04 507: 04 (72) Inventor Shinichi Sakashita 20 Satsukigaoka, Mizuguchi-machi, Koka-gun, Shiga Prefecture Yodogawa Kasei Co., Ltd.Shiga Plant (72) Inventor Toshiaki Okumura Suita, Osaka 2-8-4, Esakacho, Ichigo Yodogawa Kasei Co., Ltd. F-term (reference) 4F071 AA26 AA27 AB03 AE17 AF07 AF36 AF37 AH15 BA01 BB03 BC01 BC03 4F204 AA16 AA17 AB11 AB13 AB18 AG01 AM28 FA01 FB01 FF01 FF06 4J161 BD141 BD141 BD151 FD016 FD206 GQ00 5H026 AA06 BB01 BB02 CC03 EE06 EE19 HH05

Claims (3)

[Claims] 1. A separator having a gas-permeable groove for use in a solid polymer membrane fuel cell, wherein the separator is a molded article molded from a composition of (a) graphite and a fluororesin. (B) that the ratio of graphite to the total amount of graphite and fluororesin in the composition is G, and the ratio of fluororesin is F, In this case, G is 60 to 95% by weight, F is 40 to 5% by weight, and (C) the density D of the compact is 1.8 g / cm ³ or more. A fuel cell separator characterized by the above-mentioned. 2. The method according to claim 1, wherein the fluororesin is polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PV).
DF) and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (TH
The fuel cell separator according to claim 1, wherein the separator is at least one resin selected from the group consisting of V). 3. A method for producing a separator having a gas permeable groove for use in a solid polymer membrane type fuel cell, wherein the graphite powder and the fluororesin are mixed in a total amount of 10%.
When it is 0% by weight, a composition in which the former ratio G is 60 to 95% by weight and the latter ratio F is 40 to 5% by weight is mixed at a temperature higher than the melting point of the fluororesin. A method for producing a separator for a fuel cell, comprising compression molding under vacuum conditions to obtain a molded product having a density of 1.8 g / cm ³ or more, in which graphite forms a filler and a fluororesin forms a matrix.