JP4100086B2 - Fuel cell separator - Google Patents

Description

【００５９】
【発明の効果】
以上詳述した通り、本発明によれば、造粒助剤としてＰＶＡを用いることにより、成形時のひび割れ等の欠陥を防止して、貫通穴及びリブ付き、大面積の燃料電池セパレータであっても、歩留り良く工業的に有利に製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell separator comprising a graphite molded body, and in particular, a granulated product obtained by mixing and granulating graphite carbon microparticles and self-sintering carbon microparticles is pressure-molded and fired. The present invention relates to a fuel cell separator that can be manufactured with good surface accuracy and high yield even if it is a large-area fuel cell separator with through holes and ribs.
[0002]
[Prior art]
In recent years, fuel cells have attracted attention as an energy supply source with high power generation efficiency and excellent environmental performance. Among them, the polymer electrolyte fuel cells (PEFC) using a solid polymer as an electrolyte have attracted the most attention. This polymer electrolyte fuel cell has a catalyst layer on both sides of a film-like ion exchange membrane serving as an electrolyte, and a current collector is provided on both sides to form a membrane-electrode assembly (MEA). ing. Further, a separator provided with a groove serving as a passage for fuel is provided on the outside thereof, and hydrogen or oxygen passes between the MEA and the separator, and all of them are integrated to constitute one cell. When a potential difference of about 0.7 V is obtained with one cell, for example, 300 cells can be stacked and connected in series to form a stack that obtains a voltage of 210 V, for example.
[0003]
The separator used in this fuel cell is a plate-like body in which a thin groove (flow channel) and a through hole penetrating in the thickness direction are formed on the plate surface. The grooves formed on the plate surface meander with respect to the main region of the separator and are formed at a fine pitch for the purpose of increasing the contact area between the gas diffusion electrode and the gas. In addition, the through hole is a manifold for introducing or discharging fluid into such a groove, or a mounting hole for stack assembly, and the shape thereof is circular, oval, triangular, square, rectangular, trapezoidal. Etc., and are formed at locations according to the purpose, such as the vicinity of the side edge or the central portion of the plate-like body.
[0004]
As the performance of the separator, it is required not to allow the supplied hydrogen or oxygen gas to permeate, and since it functions as a current collector of the fuel cell, high conductivity is required. Furthermore, it is required to ensure surface accuracy in order to prevent deterioration of conductivity between the separator and the MEA, and to prevent gas leakage and short path of the gas flowing in the groove.
[0005]
Conventionally, as such fuel cell separators, those made of a graphite molded body are generally used. Therefore, a graphite molded body having such a complicated groove shape and a through hole can be obtained with good surface accuracy. It is desired to manufacture with good yield and low cost.
[0006]
As a method for producing such a graphite molded body at low cost by cold pressing, Japanese Patent Application Laid-Open No. 2000-319068 discloses a carbonaceous carbon compound having an average particle size of 10 μm or less containing a component having self-sintering properties during carbonization. Fine particles and graphitic carbon fine particles having an average particle size of 10 to 70 μm are dried and dehydrated and then mixed in a dry state. The resulting uniform mixture is mixed with an aqueous solution containing an additive for bonding particles, and mixed with stirring. A method is described in which a granulated product having a maximum particle size of 0.5 mm or less is formed, and then a dried granulated product obtained by removing moisture is subjected to pressure molding, and the resulting formed product is carbonized in a non-oxygen atmosphere. Has been. This publication describes the use of a water-soluble particle binder in order to prevent powdering during handling by increasing the strength of the granulated particles. As the particle binder, a polymer flocculant is used. Polyethylene glycol, methylcellulose, and sucrose are exemplified.
[0007]
[Problems to be solved by the invention]
However, as described in JP-A-2000-319068, when a polymer flocculant, polyethylene glycol, methylcellulose, or sucrose is used as a particle binder, a flat plate can be formed. A large-area separator having grooves on the surface and having through-holes cannot be manufactured with high yield. That is, in the method described in Japanese Patent Application Laid-Open No. 2000-319068, when trying to pressure mold a separator having a groove and a through hole on the plate surface and having a large area, cracks are likely to occur during molding, and the production yield is poor. . Particularly, in the oval through-hole formed near the edge of the plate surface along the edge and the elongated molded body portion formed between the edge, the through-hole reaches the edge of the molded body. Cracks are likely to occur, which has been a cause of impaired productivity.
[0008]
The present invention solves the above-mentioned conventional problems, granulates a mixture of graphitic carbon fine particles and self-sintering carbon fine particles, press-molds the granulated product, and then fires the graphite molded product. An object of the present invention is to provide a fuel cell separator comprising a through hole and a rib, and having a large area, which can be manufactured with high yield by preventing defects such as cracks. And
[0009]
[Means for Solving the Problems]
The fuel cell separator of the present invention granulates a mixture of graphitic carbon microparticles and self-sintering carbon microparticles having an average particle size smaller than the graphite carbon microparticles, and press-molds the resulting granulated product. In a fuel cell separator comprising a graphite molded body obtained by post-firing, a fuel cell separator using polyvinyl alcohol as a granulation aid , the total of the graphite carbon fine particles and self-sintering carbon fine particles The proportion of polyvinyl alcohol is 0.035 % by mass or more and 6.5 % by mass or less .
[0010]
According to the present invention, by using polyvinyl alcohol (PVA) as a granulation aid, defects such as cracks during molding can be prevented, and even a large-area separator with through holes and ribs can be manufactured with high yield. be able to.
[0011]
In the present invention, the average particle size of the graphitic carbon fine particles is preferably 20 μm or more and 180 μm or less, and the average particle size of the self-sintering carbon fine particles is preferably 80% or less of the average particle size of the graphitic carbon fine particles.
[0012]
The mixing ratio of the graphitic carbon particles and self-sintering carbon particles (graphitic carbon particles / self-sintering carbon particles) is 9/1 or less mass ratio, correct preferable to be 5/5 or more .
[0013]
Also, pressing pressure is 1t / cm ² (98.0MPa) or more and less 2.4t / cm ² (235MPa), it is preferred that the firing temperature is 500 ° C. or higher.
[0014]
Such a fuel cell separator of the present invention has a plate shape in which the length of one side is 10 cm or more and 100 cm or less, the thickness is 0.5 mm or more and 10 mm or less, and a groove is formed on at least one main plate surface. It is suitable for a fuel cell separator.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the fuel cell separator of the present invention will be described in detail.
[0016]
Graphite carbon fine particles used in the present invention may be either natural graphite or artificial graphite, or a mixture thereof. The average particle size of the graphitic carbon fine particles is 20 μm or more, particularly 30 μm or more, and is preferably 180 μm or less, particularly 120 μm or less. If the average particle size of the graphite carbon fine particles is too small, the moldability is poor and cracks are likely to occur during compression molding. If the average particle size is too large, the smoothness of the surface of the resulting molded body is lost, and gas leakage occurs when assembled as a fuel cell. Further, in order to give a fine groove shape to the surface of the molded body, it is necessary to use graphitic carbon fine particles having a particle diameter smaller than the groove size.
[0017]
On the other hand, the self-sintering carbon compound constituting the self-sintering carbonaceous fine particles is a carbonaceous compound that can be graphitized while maintaining its own shape by molding and firing without using a binder. Any conventionally known one can be used. Of these, gamma component (quinoline soluble, toluene insoluble component) content 3 mass% or more, preferably 5 mass% or more, 30 mass% or less, preferably to use a carbonaceous compound than 25 mass% Is preferred. When the γ component content is too small, it becomes difficult to express a desired strength within the required range of predetermined physical property values. If the γ component content is too large, it will melt at 100 ° C. or lower, such as coal tar, and the molded product shape cannot be maintained, and the self-sintering carbonaceous compound may be unevenly distributed. There is.
[0018]
Examples of commercially available self-sintering carbonaceous compounds satisfying the above γ component content include TGP series manufactured by Osaka Kasei Co., Ltd., MCMB green powder manufactured by Osaka Gas Chemical Company, and KMFC manufactured by Kawasaki Steel Company. Other high softening point pitches can also be used as self-sintering carbon fine particles as long as they satisfy the above γ component content. As long as the above γ component content range is satisfied, there is no problem whether the self-sintering carbon compound is a coal tar or a petroleum heavy oil as a starting material. Moreover, even if it is the raw material which increased oxygen content by air oxidation like MPC-1 by Osaka Kasei Co., Ltd., there is no problem as long as the γ component satisfies the above content.
[0019]
It is important that the average particle size of the self-sintering carbon fine particles is smaller than the average particle size of the graphitic carbon fine particles, preferably 80% or less (0.8 times or less) of the average particle size of the graphitic carbon fine particles, It is preferably 50% or less (0.5 times or less). That is, when the graphite carbon fine particles and the self-sintering carbon fine particles are mixed, the self-sintering carbon fine particles cover the periphery of the graphite carbon fine particles so that strength is exhibited at the time of firing. Therefore, the larger the ratio of the average particle diameter of the graphitic carbon fine particles to the average particle diameter of the self-sintering carbon fine particles, the higher the strength can be expressed with a small amount of the self-sintering carbon fine particles, which is preferable. However, since it is industrially difficult to pulverize self-sintering carbon to a particle size of 3 μm or less, the lower limit of the average particle size of self-sintering carbon fine particles is usually 3 μm or more.
[0020]
The mixing ratio of the graphitic carbon particles and self-sintering carbon particulate, graphitic carbon particles / self-sintering carbon particles = 9/1 or less in mass ratio, and in particular 8/2 or less, 5/5 or more , particularly 6/4 or more, i.e., the ratio of graphitic carbon particles 90 mass% or less relative to the total weight of the graphitic carbon particles and self-sintering carbon particles, in particular 80 mass% or less, 50 mass% or more, and especially preferably 40 mass% or more. If the ratio of the graphitic carbon fine particles is too large than this range, the self-sinterable carbon fine particles are relatively small, and the periphery of the graphite carbon fine particles cannot be sufficiently covered with the self-sinterable carbon fine particles. The sinterability tends to be insufficient, and sufficient strength cannot be expressed. On the other hand, if the amount of fine graphite carbon particles is less than this range, the amount of self-sintering carbon particles is relatively large, and shrinkage during firing tends to increase, cracking is likely to occur, and softening and melting occur. Since it becomes easy, holding | maintenance of a shape becomes difficult. In addition, it is not possible to obtain excellent effects in electrical conductivity, thermal conductivity, dimensional stability of the molded body, and the like derived from the graphitic carbon fine particles.
[0021]
Mixing of the graphite carbon fine particles and the self-sintering carbon fine particles may be performed by a dry method or a wet method, and a normal powder mixing method can be used. It is important that the carbonaceous fine particles and the self-sintering carbon fine particles are highly uniformly mixed. Mixing of the graphite carbon fine particles and the self-sintering carbon fine particles can be sufficiently performed even in a dry type.For example, the dried graphitic carbon fine particles and the self-sintering carbon fine particles are mixed with a high speed mixer (manufactured by Fukae Powtech). By using dry mixing with the, the mixture can be sufficiently uniformly mixed.
[0022]
In the present invention, a mixed powder of graphitic carbon fine particles and self-sintering carbon fine particles is granulated in order to facilitate handling during press molding and prevent dust generation. This granulation can be performed by an ordinary wet granulation method using, for example, a high speed mixer (Fukae Powtech), Granurex (Freund Sangyo) or the like.
[0023]
There is no particular limitation on the granulating agent used in such wet granulation, but in the organic solvent system, the self-sintering carbon fine particle binding component (γ component) is dissolved, and the binding property is likely to decrease. Therefore, an aqueous solvent, particularly water, is practical.
[0024]
In the present invention, PVA (polyvinyl alcohol) is used as a granulation aid, preferably dissolved in a granulation agent.
[0025]
The degree of polymerization of the PVA used is usually 400 or more, preferably 500 or more, 4000 or less, particularly 3000 or less. This degree of polymerization is 14000 or more, preferably 18000 or more, 200,000 or less, preferably 150,000 or less in terms of molecular weight. The saponification degree of PVA is 60% or more, particularly 70% or more, and preferably 100% or less.
[0026]
Granulating agents PVA, preferably at a concentration in water is 0.1 mass% or more, particularly 0.2 mass% or more, 10 mass% or less, particularly 5 mass% or less.
[0027]
The amount of granulating agent for mixing powder 100 mass portions of the graphitic carbon particles and self-sintering carbon particles, 35 mass parts or more, particularly 40 mass parts or more, 65 mass parts or less, particularly it is preferably 60 or less mass unit.
[0028]
The higher the degree of polymerization of the PVA used and the higher the concentration of PVA with respect to the granulating agent, the higher the strength of the dry granulated powder obtained. The granulated powder is not crushed, gaps are easily left in the molded body, and defects are easily generated in the molded body. In addition, if the strength of the granulated powder is too low, it is likely to be pulverized during handling, causing problems such as dust generation and poor fluidity when filling the mold. By selecting the degree of polymerization of PVA to be used and the concentration of PVA relative to the granulating agent, dry granulated powder having an appropriate strength can be produced.
[0029]
Moreover, the higher the degree of saponification of PVA and the larger the amount of granulating agent used, the larger the particle size of the granulated powder. However, even if the granulating agent is used excessively with respect to the mixed powder of the graphite fine particles and the self-sintering carbon fine particles, the effect is saturated. Conversely, the lower the degree of saponification of PVA and the smaller the amount of granulating agent used, the smaller the particle size of the granulated powder. However, the amount of granulating agent used varies between the graphite fine particles and the self-sintering carbon fine particles. If the amount is too small relative to the mixed powder, it becomes difficult to sufficiently wet the mixed powder and granulation becomes difficult. By selecting the degree of saponification of the PVA used and the amount of granulating agent used, granulated powder having a desired particle size can be obtained.
[0030]
Thus, depending on the polymerization degree and saponification degree of PVA as a granulation aid, the PVA concentration and the amount of granule used so that a granulated powder having a desired particle size and appropriate strength can be obtained as described above. is determined, the amount of PVA is, granulated powder, i.e., 0.035 mass% or more to the total of the graphitic carbon particles and self-sintering carbon particles, especially 0.1 mass% or more, further 0.3 mass% or more, 6.5 mass% or less, particularly 6 mass% or less, more is preferably 3 mass% or less.
[0031]
The temperature during the granulation operation can be selected within the range where the granulation aid used is a liquid and the granulation aid becomes a solution of the granulation agent. Specifically, when water is used as the granulating agent, the temperature during the granulating operation is 0 ° C. or higher, preferably 10 ° C. or higher, 80 ° C. or lower, preferably 60 ° C. or lower.
[0032]
In addition, in this invention, arbitrary mold release agents can also be used together as a granulation adjuvant other than PVA. In the case of a release agent that dissolves in the granulating agent, it may be used after being dissolved in the granulating agent. For example, in the case of an aqueous granulating agent, water-soluble polyethylene glycol can be used as it is. A release agent having a low solubility in the granulating agent may be used after being dispersed as an emulsion in the granulating agent.
[0033]
The granulated product obtained in this way can be obtained by any known dryer such as a hot air dryer such as a box type or a fluidized bed, a heat transfer dryer such as a stirring type or a drum type, an infrared dryer or a microwave dryer. It is dried to obtain dry granulated powder, which is subjected to sieving treatment as necessary with a normal sieving machine such as a low tap or a vibration sieving machine, and then subjected to molding.
[0034]
There are no particular restrictions on the drying conditions for this granulated product, but if it is too low, it takes too much time to dry, so it is usually 20 ° C or higher, preferably 60 ° C or higher, more preferably 100 ° C or higher. Since the sinterability of the sinterable carbon fine particles may be lowered, it is preferably 160 ° C. or lower, 140 ° C. or lower, and more preferably 120 ° C. or lower.
[0035]
The dry granulated powder to be used for molding preferably has an average particle size of 0.1 mm or more, particularly 0.2 mm or more, more preferably 0.3 mm or more and 10 mm or less, particularly 5 mm or less, further 3 mm or less. When the average particle size of the dried granulated powder is too large, it becomes difficult to fill the mold. If the average particle size of the dry granulated powder is too small, the flowability at the time of filling the mold tends to deteriorate, and not only it becomes difficult to uniformly fill, but also the degassing property at the time of pressing tends to deteriorate. , Press takes time.
[0036]
The dry granulated powder is molded by compression molding using a mold in which the desired separator shape is cut on the pressing surface. You may apply | coat (spray) well-known arbitrary mold release agents, such as silicone oil, to the metal mold | die used for shaping | molding. This pressure molding can be performed by a uniaxial press, a biaxial press, a rotary press, a wet isostatic press, a dry isostatic press, etc., and the press pressure is 1 t / cm ² (98.0 MPa) or more, preferably 1.2 t / cm ² (118 MPa) or more, 2.4t / cm ² (235MPa) less, preferably in the following 2.2t / cm ² (216MPa). If the pressing pressure is too low, the strength of the resulting molded body is not sufficient, and if it is too high, cracking and cracking will occur due to the phenomenon of springback that causes blistering when the pressure is released.
[0037]
The obtained molded body is preferably fired out of the mold in consideration of productivity.
[0038]
The maximum temperature for firing is usually 500 ° C. or higher, preferably 550 ° C. or higher, particularly preferably 600 ° C. or higher. Usually, the maximum temperature may be set according to the desired graphitization degree from the physical properties such as electrical conductivity, but in the present invention, since the graphite content in the raw material is high, even at a maximum temperature of 1500 ° C. or less, especially 1000 ° C. or less. A sufficient degree of graphitization is obtained.
[0039]
The heating rate during firing is 20 ° C./h or less, and preferably 15 ° C./h or less. If the heating rate is too fast, the molded body will be cracked and blistered easily. In order to save energy, a faster heating rate is better, and if the heating rate is too slow, production efficiency tends to decrease, so it is usually 0.01 ° C / h or higher, especially 0.05 ° C / h or higher. Is preferred.
[0040]
In addition, in order to prevent the oxidation at the time of baking, it is preferable to perform baking by making the inside of a furnace into inert atmosphere, such as nitrogen and argon, or burying a molded object in coke breeze.
[0041]
Although it may cool after baking, it can also be forcedly cooled to improve productivity.
[0042]
The fuel cell separator of the present invention thus obtained is, for example, a plate shape having a thickness of 0.5 mm or more, preferably 1 mm or more, 10 mm or less, preferably 5 mm or less, and vertical and horizontal dimensions of 50 mm or more, preferably 100 mm. As mentioned above, it is 1000 mm or less, preferably 500 mm or less.
[0043]
Usually, a separator is provided with a groove that serves as a passage for fluids such as fuel gas, oxygen, and cooling water on one or both sides, and the width is usually 0.1 mm or more, preferably 0.3 mm or more, preferably 10 mm or less, preferably 5 mm. In the following, the depth is usually 0.1 mm or more, preferably 0.3 mm or more, 9 mm or less, preferably 5 mm or less.
[0044]
Furthermore, a through hole serving as a manifold for introducing or outflowing fluid into such a groove or a through hole used during stack assembly can be formed.
[0045]
A single cell and a stack of a fuel cell can be assembled using the fuel cell separator of the present invention thus manufactured. As described above, the main constituent members of a single cell of a polymer electrolyte fuel cell are a membrane / electrode assembly, a separator with a groove and a through hole. The basic structure of the membrane / electrode assembly is such that a catalyst layer, a gas diffusion layer, and a current collector are sequentially joined to both surfaces of a polymer solid electrolyte membrane (ion exchange membrane). The catalyst layer is mainly composed of a mixture of a catalyst and carbon black. The gas diffusion layer may also function as a current collector. A single cell of a polymer electrolyte fuel cell is formed by joining a separator with a groove and a through hole according to the present invention to both surfaces of the membrane electrode body. A plurality of single cells can be stacked in series and used as a stack.
[0046]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[0047]
Example 1
300 g of self-sintering carbonaceous compound fine particles with an average particle size of 3 μm that reached a constant dry weight in a hot air circulation dryer maintained at 110 ° C. (obtained by pulverizing “TGP3000” manufactured by Osaka Kasei Co., Ltd. with a jet mill), 700 g of graphite carbon fine particles with an average particle size of 29 μm (manufactured graphite “SLM44” manufactured by Timical Co., Ltd.) are charged into a high speed mixer (LFS-GS-2J type) manufactured by Fukae Powtech Co., and dry nitrogen is supplied from the agitator and chopper shaft. The mixture was blown out and stirred for 5 minutes at an agitator rotation speed of 500 rpm and a chopper rotation speed of 1000 rpm. The powder was smoothly mixed when observed through the viewing window of the lid.
[0048]
Polyvinyl alcohol (Nippon Gosei GOHSENOL "KH-20", the polymerization degree of 2000 or more, degree of saponification 80) 2 mass% aqueous solution 400g of a granulating and granulating aids, agitator rotational speed 2000 rpm, chopper rotational speed 500rpm The mixture was poured into the above mixture for 2 minutes and granulation was continued for 3 minutes. The obtained granulated product was dried with a hot air circulating dryer at 120 ° C. and then cooled to room temperature. The dried granulated product was separated on the sieve using a sieve having a mesh size of 3 mm, and 99% or more was recovered as the sieve.
[0049]
A single-shaft 1500-ton type press was installed with a 130.0mm long x 260.0mm wide die, and grooves called serpetines and ridges for forming through holes were installed on the upper and lower press surfaces. 62g of undergranulated granulated material (average particle size 0.5mm) is put into this mold, press-molded with a molding pressure of 1.4t / cm ² (137MPa), thickness 1.8mm, depth 0.5mm on the plate surface A groove having a width of 2 mm and an oval through hole formed in the vicinity of the side edge and a molded body with a through hole were obtained.
[0050]
The upper and lower surfaces of the compact were sandwiched between 10 mm thick graphite plates, and the graphite plates were placed in a stainless steel container. The stainless steel container was placed in a larger stainless steel container and the periphery was covered with coke breeze. Place the vessel in an electric furnace and supply nitrogen at a supply rate of 20 L / min for 0.5 hours from room temperature to 170 ° C, 86.5 hours from 170 ° C to 400 ° C, 15 hours from 400 ° C to 550 ° C, 550 The temperature was raised from 5 ° C to 700 ° C in 5 hours, maintained at 700 ° C for 1 hour, and then cooled in the furnace.
[0051]
The obtained graphite compact gave a linear shrinkage of 0.2% compared to the dimension before firing. The grooves and through holes formed by the mold were carbonized as they were, and no defects such as distortion and cracks were observed.
[0052]
Example 2
The same operation as in Example 1 was performed except that GOHSENOL “NL-05” (degree of polymerization less than 1000 and saponification degree of 98% or more) manufactured by Nippon Gosei Co., Ltd. was used as the polyvinyl alcohol. A good graphite molded body could be obtained from the molded body. In this graphite molded body, the grooves and through-holes formed by the mold were carbonized as they were, and no defects such as distortion and cracks were observed.
[0053]
Comparative Example 1
As granulating and granulating aids, other using sucrose aqueous solution (10 mass%) is, as a result of working in the same manner as in Example 1, at the time of press molding, molding and the through-hole of the molded body outer peripheral portion outside Cracks occurred in the molded part between the circumference and the product could not be made.
[0054]
Comparative Example 2
As granulating and granulating aids, polyethylene glycol (PEG, molecular weight 20000) except that using an aqueous solution (2 mass%) is, as a result of working in the same manner as in Example 1, at the time of press molding, the molded body periphery Cracks occurred in the molded body part between the through hole of the part and the outer periphery of the molded body, and the product could not be obtained.
[0055]
Comparative Example 3
As granulating and granulating aids, polyethylene glycol (PEG, molecular weight 4000) except that using an aqueous solution (2 mass%) is, as a result of working in the same manner as in Example 1, at the time of press molding, the molded body periphery Cracks occurred in the molded body part between the through hole of the part and the outer periphery of the molded body, and the product could not be obtained.
[0056]
Comparative Example 4
As granulating and granulating aids, other using ammonium polycarboxylate solution (2 mass%) is, as a result of working in the same manner as in Example 1, at the time of press molding, the through-hole of the molded body outer peripheral portion Cracks occurred in the part of the molded body between the outer periphery of the molded body and the outer periphery of the molded body, making it impossible to produce a product.
[0057]
The results of the above examples and comparative examples are summarized in Table 1.
[0058]
[Table 1]

[0059]
【The invention's effect】
As described above in detail, according to the present invention, by using PVA as a granulating aid, it is possible to prevent defects such as cracks during molding, and to provide a large area fuel cell separator with through holes and ribs. However, it can be produced industrially advantageously with a high yield.

Claims (8)

Graphite obtained by granulating a mixture of graphitic carbon fine particles and self-sintering carbon fine particles having an average particle size smaller than that of the graphitic carbon fine particles, press-molding the obtained granulated product, and firing the mixture In a fuel cell separator made of a molded body,
A fuel cell separator using polyvinyl alcohol as a granulating aid ,
A fuel cell separator, wherein a ratio of polyvinyl alcohol to a total of the graphite carbon fine particles and the self-sintering carbon fine particles is 0.035 % by mass or more and 6.5 % by mass or less .   2. The fuel cell separator according to claim 1, wherein the graphite carbon fine particles have an average particle size of 20 μm or more and 180 μm or less. According to claim 1 or 2, the mixing ratio of the graphite quality carbon particles and self-sintering carbon particles (graphitic carbon particles / self-sintering carbon particles) is 9/1 or less mass ratio, 5/5 or more A fuel cell separator.   4. The fuel cell separator according to claim 1, wherein the average particle size of the self-sintering carbon fine particles is 80% or less of the average particle size of the graphitic carbon fine particles. 5. 5. The aqueous solution of 0.1 to 5% by mass of polyvinyl alcohol with respect to the mixed powder obtained by dry-mixing the graphitic carbon fine particles and the self-sintering carbon fine particles according to claim 1. and as a granulating agent and granulating aids, a fuel cell separator, wherein granulation to isosamples injected into the mixed powder during mixing. In any one of claims 1 to 5, a fuel cell separator, wherein said pressure molding pressure of 1t / cm ² (98.0MPa) or more and less 2.4t / cm ² (235MPa).   The fuel cell separator according to any one of claims 1 to 6, wherein the firing temperature is 500 ° C or higher.   The plate according to any one of claims 1 to 7, wherein the length of one side is 10 cm or more and 100 cm or less, the thickness is 0.5 mm or more and 10 mm or less, and a groove is formed on at least one main plate surface. A fuel cell separator.