KR101089412B1 - Manufacturing method of a separator for a fuel cell and separator for a fuel cell - Google Patents

Abstract

Provided are a method for producing a fuel cell separator and a fuel cell separator that can improve productivity and durability of a fuel cell without causing a decrease in mechanical properties, poor molding, and lack of conductivity. The linear material polyphenylene sulfide resin and the powdered artificial graphite are mixed to prevent the polyphenylene sulfide resin from melting to prepare a molding material 5, and the molding material 5 is filled into the mold 6 to be heated and pressurized. After that, it is press-cooled and demolded from the mold 6. Since the separator for fuel cell is molded by the molding material (5) mixed with linear polyphenylene sulfide resin and artificial graphite, excellent heat resistance and water resistance can be obtained, and elution ions and heavy metal powders that adversely affect the durability of the fuel cell are contained. Less fuel cell separators can be produced.

Fuel cell, separator, polyphenylene sulfide, graphite, mold

Description

Manufacturing method of separator for fuel cell and separator for fuel cell {MANUFACTURING METHOD OF A SEPARATOR FOR A FUEL CELL AND SEPARATOR FOR A FUEL CELL}

BRIEF DESCRIPTION OF THE DRAWINGS It is a plan explanatory drawing which shows typically embodiment of the fuel cell separator which concerns on this invention.

2 is a cross-sectional explanatory diagram schematically showing an embodiment of a fuel cell separator according to the present invention.

It is sectional explanatory drawing which shows typically the metal mold | die in embodiment of the manufacturing method of the fuel cell separator which concerns on this invention.

It is a graph which shows typically embodiment of the fuel cell separator which concerns on this invention.

<Description of the symbols for the main parts of the drawings>

Separators for fuel cells

2 base plate

3 Groove

5 forming material

6 mold

7upper mold

8 lower mold

9 molding part

Patent Document 1: Japanese Patent Publication No. 2003­100313

Patent Document 2: Japanese Patent No. 3693275

Patent Document 3: Japanese Patent Publication No. 2003­346827

Patent Document 4: Japanese Patent Application Laid-Open No. 2001­085030

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fuel cell separator and a fuel cell separator for contributing to global warming prevention, energy saving, and the like.

The fuel cell separator used for a fuel cell is required to have conductivity, mechanical properties, and durability as important characteristics, but in addition to these, high productivity is required in order to realize low price and spread.

When manufacturing such a fuel cell separator, although not shown, conventionally, a method of mixing and molding a predetermined amount of a predetermined resin and graphite is employed (see Patent Documents 1, 2, 3, and 4). As predetermined resin, a thermoplastic resin or a thermosetting resin is mentioned. Moreover, graphite is melt-kneaded by mix | blending many with predetermined resin in order to ensure electroconductivity.

Conventionally, the fuel cell separator is manufactured as described above, and the graphite is increased in order to secure the conductivity. However, when the graphite is increased, the fluidity of the molding material is greatly deteriorated, and the molding material is formed on the irregularities and ends of the separator. Cannot be sufficiently filled, resulting in a decrease in mechanical properties or poor molding. In the case of Patent Documents 1 and 2, thermoplastic resins are used. However, when the thermoplastic resin and the graphite of the powder are melt-kneaded and molded, the thermoplastic resin excessively adheres to the periphery of the graphite during melt-kneading, thereby inhibiting conductivity and There is not much concern about this shortage.

In the case of Patent Documents 3 and 4, thermosetting resins are used. However, the curing of the thermosetting resins requires a long time, which leads to difficulty in productivity. In addition, since uncured components and reaction products tend to remain as residues in the separator for fuel cells, such residues elute during operation of the fuel cells, thereby degrading the durability of the fuel cells. In order to eliminate this drawback, in the past, the residue is removed by post-heating, but a sufficient effect cannot be expected, resulting in a decrease in productivity.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and a method for producing a fuel cell separator and a fuel cell separator that can improve productivity and durability of a fuel cell without causing a decrease in mechanical properties, poor molding, and lack of conductivity. The purpose is to provide.

In this invention, in order to solve the said subject, as a manufacturing method of the fuel cell separator which provided the groove | channel which divides the flow path for fuel in at least one surface of a base board, a powder type linear polyphenylene sulfide resin And powdered artificial graphite are mixed so that the polyphenylene sulfide resin is not melted, a molding material is prepared, and the molding material is filled into a mold and heated and pressurized, followed by demolding.

Moreover, it is preferable to mix | blend polyphenylene sulfide resin and artificial graphite in the ratio of 1: 2.5-1: 5 by weight ratio.

Moreover, it is preferable to mix | blend 300-500 weight part of artificial graphite with respect to 100 weight part of polyphenylene sulfide resin.

Moreover, after wash | cleaning polyphenylene sulfide resin, it is preferable to mix with artificial graphite of powder.

Moreover, it is preferable to prepare artificial graphite by mixing rod-like graphite in block graphite, and to make ratio of the diameter and length of this rod-shaped graphite into 1: 3-20.

Moreover, what is necessary is just to fill the lower mold | die of the metal mold | die with the weighing | molding molding material, and to make it substantially uniform, and to scrape away the molding material of the shaping part of the metal mold | die which forms a groove | channel.

Moreover, in this invention, in order to solve the said subject, it is a fuel cell separator manufactured by the manufacturing method of the fuel cell separator of any one of Claims 1-4, and it measures by a Loresta resistivity meter. It is characterized by the volume resistivity which becomes 6 m (ohm) * cm or less.

Here, the groove | channel which partitions the flow path for fuels in a claim is provided with the required number on the surface, back surface, or front and back surface of a base plate. In addition to the artificial graphite, artificial graphite includes graphite in which residual metal components, elution ions, etc. have been removed by acid washing or heating at 1000 ° C or higher.

EMBODIMENT OF THE INVENTION Hereinafter, with reference to drawings, preferred embodiment of this invention is described, The fuel cell separator 1 in this embodiment is a polyphenylene sulfide resin and a conductive filler (as shown to FIG. 1 thru | or 3). artificial graphite, which is a filler, is mixed to prepare a molding material 5, the molding material 5 is filled into the mold 6, heated and pressurized, and then press-cooled to be demolded from the mold 6 to be compression molded. The volume resistivity measured by the four-terminal four-probe method of a lorsta resistivity meter based on JISK7194 becomes 6 m (ohm) * cm or less.

As shown in FIG. 1 and FIG. 2, the fuel cell separator 1 includes a base plate 2 of a substantially planar shape, and at the center of the substantially flat front and back surfaces of the base plate 2, The plurality of grooves 3 for dividing the fuel flow path are arranged side by side in a substantially S-shaped plane, respectively, and are stacked together with an electrolyte layer, an air electrode, and a fuel electrode (not shown) to function as a fuel cell. The plurality of grooves 3 are perforated side by side with a plurality of through-holes 4 having a rectangular shape around them, and each of the grooves 3 is formed to be concave in a substantially U-shaped cross section.

The molding material 5 is prepared by mixing a pulverized linear type polyphenylene sulfide (PPS) resin and powdered artificial graphite so that the polyphenylene sulfide resin does not melt.

The use of polyphenylene sulfide resin is optimal in practical use, but for example, in the case of liquid crystal polymer, there is a fear of a decrease in strength over time due to hydrolysis peculiar to the polyester resin, In the case of polypropylene (PP; polypropylene), there is a problem of eluting ions due to the lack of mechanical strength or the influence of antioxidants. In the case of crystalline resins made of polycarbonate (PC), polyetherimide (PEI), polyethersulfone (polyethersulfone) and the like, problems such as lack of toughness due to insufficient filling of graphite Because it occurs.

It is preferable to use polyphenylene sulfide resin after washing | cleaning with an acid, water, etc. from a viewpoint of prevention of elution ion. This is because when the polyphenylene sulfide resin is washed and used, ions eluted in hot water during operation of the fuel cell can be reduced, and deterioration of the fuel cell can be prevented. Elution of ions can be evaluated by immersing 1 g of polyphenylene sulfide resin in 4 g of pure water, leaving 100HR in a pressure cooker at 121 ° C, and measuring the conductivity of pure water. The conductivity of pure water is preferably 100 μS (Siemens) or less.

In order to obtain high fluidity, the polyphenylene sulfide resin is preferably a linear type, not a crosslinking type. The weight average molecular weight of this linear type polyphenylene sulfide resin is optimal in the range of 25000-100000. This is because when the weight average molecular weight is less than 25000, the mechanical strength is insufficient. On the contrary, when the weight average molecular weight is more than 100000, fluidity deteriorates and good molding cannot be expected.

As an index of the fluidity of the polyphenylene sulfide resin, when it is understood by the melt flow rate (MFR (melt flow rate): solution index), at a melting point of + 100 ° C, a pressure of 100 kg / cm ² , a die diameter of 1 mm, and a land length of 10 mm The melt flow rate of is 300 cc / 10 minutes to 1200 cc / 10 minutes, preferably 400 cc / 10 minutes to 1000 cc / 10 minutes. This is based on the reason that when less than 300 cc / 10 minutes, the flowability is small and good molding cannot be performed. On the contrary, it is based on the reason that sufficient mechanical properties cannot be obtained when it exceeds 1200 cc / 10 minutes.

Artificial graphite is not a natural type, but artificial type, specifically, tar and cokes are fired at high temperature, and a type and a pulverized organic material such as phenol are pulverized to a predetermined particle diameter. The type is used and adjusted to an average particle diameter of 30 to 200 µm, preferably 50 to 150 µm. When graphite is a natural type, since various impurities are mixed, in order to use it as the fuel cell separator 1, residues made of iron, silicon, ash and the like, and elution ions such as sodium and chlorine are removed. For this reason, it is necessary to volatilize and remove at an acid wash or at a temperature of 1000 ° C or higher, and as a result, the manufacturing cost increases.

Artificial graphite is selected in the form of lumps, rods, spheres, and fibrous shapes, or a plurality of shapes are used in combination depending on the characteristics of importance. This artificial graphite is preferably a type in which 10-40 parts by weight of rod-like graphite is mixed in the bulk graphite 100 from the viewpoint of satisfactorily satisfying the conductivity, mechanical properties, and moldability. This is because the surface of the bulk graphite is monolithic, which contributes to the improvement of conductivity and mechanical properties. This is because the bending strength is improved by mixing rod-like graphite.

The rod-shaped graphite is a non-fibrous type having a diameter and length ratio of about 1: 3 to 20. This is because, in the case of fibrous graphite, good dispersibility cannot be obtained by entanglement with each other when mixing at room temperature.

In addition, in the case where the artificial graphite has a rounded shape or spherical shape, the mechanical strength is reduced. However, since the fluidity of the molding material 5 is improved, there is a significance when the productivity and dimensional accuracy are improved. Therefore, artificial graphite may be a type in which rod-shaped graphite, rounded graphite, and / or spherical graphite are mixed in the bulk graphite.

In the above, when manufacturing the fuel cell separator 1, first, the linear type polyphenylene sulfide resin is pulverized and powdered, and the polyphenylene sulfide resin and the artificial graphite of the powder are polyphenylene sulfide. The molding material 5 is prepared by mixing without heating the resin at a predetermined ratio so that the resin does not melt.

As a method of grinding | pulverizing polyphenylene sulfide resin, the freeze grinding method, the impact crushing method, etc. are employ | adopted. It is preferable that the average particle diameter of the polyphenylene sulfide resin of this powder is 1.5 micrometers or less of the average particle diameter of artificial graphite, and is 10 micrometers or more. This is because when the average particle diameter of the artificial graphite is more than 1.5 times, the polyphenylene sulfide resin in the molding material 5 decreases, resulting in resin staining in the fuel cell separator 1 and nonuniformity of characteristics. to be. Moreover, when less than 10 micrometers, it is a thing which grind | pulverizes and scatters in a manufacturing process, and a manufacturing environment worsens.

Polyphenylene sulfide resin and artificial graphite are mix | blended in the ratio of 1: 2.5-1: 5 by weight, Preferably it is 1: 3-1: 4.5. This means that when the artificial graphite is less than 1: 2.5, the volume resistivity of the separator 1 for fuel cell measured by a Loresta resistivity meter is 6 mΩ · cm or more, and conversely, when artificial graphite is larger than 1: 5, It is because the fluidity | liquidity of the material 5 deteriorates, and the thickness dimension precision of +/- 30 micrometers required for each fuel cell separator 1 cannot be obtained. In addition, for the mixing of polyphenylene sulfide resin and artificial graphite, a tumbler, a Henschel mixer, etc. are used, for example.

In addition, when the fluidity of polyphenylene sulfide resin was grasped | ascertained by the melt flow rate, the melt flow rate in melting | fusing point +100 degreeC, pressure 100kg / cm <^2> , dice diameter 1mm, land length 10mm is 300cc. 10 minutes to 1200 cc / 10 minutes is good. Explaining this point, if the linear expansion coefficient of the fuel cell separator 1 which is a molded article is greatly changed by the blending ratio of artificial graphite, and the difference with the linear expansion coefficient of the steel constituting the mold 6 becomes too large, the mold When demolding from (6), the grooves 3 and the like of the fuel cell separator 1 are caught, and when taken out, there is a risk that the product may be damaged or the fuel cell separator 1 may be damaged.

Although the linear expansion coefficient of the metal mold | die 6 is 11-12 (ppm) generally, when the weight ratio of polyphenylene sulfide resin and artificial graphite is 1: 5, it is 6 (ppm) and the weight ratio of polyphenylene sulfide resin and artificial graphite. Is 1: 4 when the weight ratio of polyphenylene sulfide resin and artificial graphite is 1: 3, and is 14 (ppm) when the weight ratio is 1: 3. ) A lot of breakage or damage occurs.

4 is a graph of melt flow rate measured under conditions of a molding material 5 at 320 ° C., a flow path diameter of 2 mmφ, a land length of 5 mm, and a pressure of 500 kg / cm ² . Here, the molding material 5 is prepared by mixing a linear type polyphenylene sulfide resin having a weight average molecular weight of 36000 and artificial graphite, and artificial graphite has an average particle diameter of 145 μm in a bulk graphite having an average particle diameter of 70 μm. It is prepared by mixing rod-like graphite.

The melt flow rate of the molding material 5 can be utilized as an index of P workability. As a result of the experiment, the melt flow rate measured under the conditions of a flow path diameter of ² mm φ, a land length of 5 mm, and a pressure of 500 kg / cm ² was obtained by using values within the range of 300 cc / 10 min to 1000 cc / 10 min. It has been found that the separator 1 for fuel cell can be stably formed with a thickness accuracy of ± 30 μm per sheet.

Such a value becomes substantially the same as that of the molding material 5, even if the fuel cell separator 1 is crushed and the melt flow rate is evaluated. Therefore, it is preferable that the melt flow rate measured on the conditions of the flow path diameter 2mm (phi), land length 5mm, and pressure 500kg / cm <^2> of the 320 degreeC fuel cell separator 1 in this embodiment is 300cc / 10min.

Artificial graphite of the polyphenylene sulfide resin and the powder is mixed without heating so that the polyphenylene sulfide resin does not melt. This is based on the reason that, when heated and melt-kneaded, the polyphenylene sulfide resin adheres excessively around the artificial graphite to inhibit conductivity and reduce energy costs.

When the molding material 5 is prepared, a predetermined amount of the mold 6 is filled (see FIG. 3) without preforming the molding material 5, the upper mold 7 and the lower mold 8 are tightened, and the mold ( 6) is heated and pressurized to compression-form the fuel cell separator 1.

When the molding material 5 is filled, since the molding amount of the molding material 5 differs from the base plate 2 of the fuel cell separator 1 and the plurality of grooves 3, the filling material 5 is filled in consideration of this. Specifically, (1) the metal mold 6 for filling the lower mold 8 of the metal mold 6 with the weighing molding material 5 uniformly and uniformly by a scrabble or the like to form a plurality of grooves 3. The method of filling the molding material 5 in a balanced manner by scraping the molding material 5 of the molding part 9 of the molding part 9 by the scrubber etc., (2) taking into account the shape of the fuel cell separator 1, The lower mold 8 of the metal mold | die 6 is filled with the molding material 5 with a dispenser, and the method of filling is mentioned.

On the occasion of filling the molding material 5, it is preferable to keep the molding temperature of the mold 6 lower than the melting point of the polyphenylene sulfide resin. Moreover, in the case of the heating pressurization of the metal mold | die 6, it sets and heats and presses between the pair of hot plates which heated the metal mold 6 filled with the molding material 5 to predetermined temperature of the molding machine. Moreover, as for the heating temperature of the metal mold | die 6, melting | fusing point +100 degreeC-+150 degreeC of polyphenylene sulfide resin is preferable, and the pressurization pressure of the metal mold | die 6 needs 300 kg / cm <^2> or more.

When the die 6 is heated and pressurized, the molding material 5 is pressurized, and a plurality of artificial graphites come into contact with each other to form voids in which the polyphenylene sulfide resin flows in between. Then, by heating the mold 6, the polyphenylene sulfide resin begins to flow in the temperature range exceeding the melting point of the polyphenylene sulfide resin, and the polyphenylene sulfide resin flows between the plurality of artificial graphites. do. Therefore, the polyphenylene sulfide resin does not adhere excessively around the artificial graphite, and good conductivity can be obtained.

The heat pressurization time of the die 6 may be any time required for the polyphenylene sulfide resin to flow between the plurality of artificial graphites. Specifically, it is 20 to 100 seconds under the conditions of the melting point + 100 ° C of the polyphenylene sulfide resin and the pressurization pressure 800 kg / cm ² (relative to the projected area of the fuel cell separator 1).

After that, the die 6 is pressurized and cooled to demold the fuel cell separator 1, whereby the fuel cell separator 1 shown in Figs. 1 and 2 can be manufactured. As a method of pressurizing (pressurizing pressure 800 kg / cm <^2> ) the die 6, it is a method of (1) removing the die 6, setting it between a pair of hot plates of another cooled molding machine, and carrying out pressure cooling (2 ) Pressurized cooling with the metal mold | die 6 set between a pair of hot plates of a molding machine, etc. are mentioned.

The metal mold | die 6 is cooled below melting | fusing point of polyphenylene sulfide resin, Preferably melting | fusing point -100 degrees C or less of polyphenylene sulfide resin, More preferably, it is below glass transition point of polyphenylene sulfide resin. This is because, when the mold 6 is cooled to such a temperature, the conductivity of the separator for fuel cell 1 is improved, which contributes to the reduction of bending and bending.

However, since the productivity deteriorates with the decrease in the cooling temperature, the fuel cell separator 1 is demolded at a high temperature within a range satisfying the conductivity, and is annealed at a temperature equal to or higher than the glass transition point, thereby separating the fuel cell separator 1 ) You can correct the bending and bending of the). The annealing is preferably carried out by stacking the fuel cell separator 1 and mounting a weight of 0.05 kg / cm ² .

According to the above, rather than injection molding the separator 1 for fuel cell with the molding material 5 in which the linear type polyphenylene sulfide resin and artificial graphite are mixed, it is compression-molded so that excellent heat resistance and water resistance can be obtained. The fuel cell separator 1 having less eluting ions or heavy metal powder can adversely affect the durability of the fuel cell.

In addition, since the amount of resin can be increased and the amount of graphite can be reduced by compression molding, extremely good conductivity can be ensured with a small amount of artificial graphite, and the dimensional accuracy is improved without causing a decrease in mechanical properties or poor molding. You can also promote In addition, since the polyphenylene sulfide resin is mixed without heating so as not to melt, the polyphenylene sulfide resin may be excessively adhered to the vicinity of the artificial graphite, thereby effectively eliminating the possibility of inhibiting conductivity or insufficient conductivity. Done.

In addition, a heating mechanism may be used when the molding material 5 is filled into the mold 6 and heated and pressurized, or a cooling mechanism may be used when pressurized cooling. This slightly increases the cost of the plant, but is advantageous as an energy cost measure. Specifically, the metal mold | die 6 can provide the heating mechanism which consists of an electric heater, or can incorporate the cooling mechanism which consists of a flow path for cooling water. In addition, a flow path may be built in the mold 6 to distribute the heating steam or cooling cooling water. When using this steam, when superheated steam is used, high temperature can be obtained at normal temperature and a favorable heating effect rate can be obtained.

<Examples>

EMBODIMENT OF THE INVENTION Hereinafter, the Example of the manufacturing method of the fuel cell separator and the fuel cell separator which concern on this invention is demonstrated with a comparative example.

Example  One

First, 3 weight ratios of artificial graphite of powder were mixed with the tumbler for 1 hour with respect to the linear type polyphenylene sulfide resin 1 of powder, and the molding material was prepared. Polyphenylene sulfide (polyphenylenesulfide) resin was pulverized by crushing a product having a weight average molecular weight of 36000 (Toray Co., Ltd. product: product name E2180) to an average particle diameter of 70 µm. In addition, the artificial graphite used the product (Oriental Carbon Co., Ltd. product: product name 8020S) of 140 micrometers of average particle diameters.

When the molding material was prepared so that the polyphenylene sulfide resin did not melt, the molding material was uniformly filled in a mold and heated and pressurized. On the occasion of filling the molding material, the molding material of the molding part of the mold for forming the plurality of grooves of the separator for fuel cell is scraped off by a scrabble or the like, and the molding material is well balanced. Moreover, when heat-pressurizing a metal mold | die, the metal mold | die was mounted in the compression molding machine whose hotplate temperature is 440 degreeC, and the pressure of 800 kg / cm <^2> was made to act on the area of the separator for fuel cells.

Next, when the mold is heated and pressurized, and the temperature of the mold reaches 400 ° C, the mold is transferred to a compression molding machine for cooling having a hot plate temperature of 30 ° C, mounted under pressure, and then subjected to press-cooling, followed by demolding from the mold. A separator for a fuel cell having an external shape of 2 mm was obtained. In the fuel cell separator, the grooves formed on both front and back sides are 210 mm x 170 mm, the width of each groove is 1 mm, and the depth of each groove is 0.7 mm.

When manufacturing the fuel cell separator, the conductivity, thickness nonuniformity, and elution conductivity of the separator for fuel cell were measured and evaluated, respectively, and are summarized in Table 1. The conductivity of the separator for fuel cell was cut out of the flat portion around the separator for fuel cell, and measured by a four-terminal method using a lorsta resistivity meter (manufactured by Mitsubishi Chemical).

About the thickness nonuniformity of the separator for fuel cells, 35 points of the separator for fuel cells were measured with the macrometer. In addition, about the elution conductivity of the fuel cell separator, some 30 g of the fuel cell separator is cut at approximately 15 mm corners, soaked in 120 g of pure water, and left at 100 hr in a pressure cooker at 121 ° C. to 23 ° C. It was evaluated by measuring the conductivity of pure water after turning.

Example  2

4.5 weight ratios of the artificial graphite of powder were mixed with the tumbler with respect to the linear type polyphenylene sulfide resin 1 of powder for 1 hour, and the molding material was prepared. Other parts were evaluated in the same manner as in Example 1.

Example  3

To the linear type polyphenylene sulfide resin 1 of powder, artificial graphite 3 weight ratio of powder was mixed with a tumbler for 1 hour, and the molding material was prepared. As the artificial graphite, a product (Oriental Carbon Co., Ltd. product: product name AT-5) X having an average particle diameter of approximately 50 µm was used. Other parts were evaluated in the same manner as in Example 1.

Example  4

To graphite linear polyphenylene sulfide resin 1 of powder, 3 weight ratios of graphite of powder were mixed with a tumbler for 1 hour, and the molding material was prepared. Graphite was washed with natural products (manufactured by Nippon Graphite Co., Ltd .: product name CGC100), washed with sulfuric acid, washed with water, heated to 3HR at 1300 ° C, and purified to an impurity level equivalent to that of natural graphite. Other parts were evaluated in the same manner as in Example 1.

Comparative example  One

To the crosslinked polyphenylene sulfide resin 1, 2.5 parts by weight of artificial graphite in powder was mixed with a tumbler for 1 hour to prepare a molding material. Other parts were evaluated in the same manner as in Example 1.

Comparative example  2

5 weight ratios of artificial graphite of powder were mixed for 1 hour with the tumbler with respect to the polyphenylene sulfide resin 1 of crosslinking type, and the molding material was prepared. Other parts were evaluated in the same manner as in Example 1.

Comparative example  3

With respect to the crosslinked polyphenylene sulfide resin 1, 3 weight ratios of graphite of the powder were mixed with a tumbler for 1 hour to prepare a molding material. As the graphite, a natural product having an average particle diameter of approximately 100 µm (Japanese Graphite Co., Ltd. product: CGC100) was used as it is. Other parts were evaluated in the same manner as in Example 1.

Comparative example  4

The graphite 3 weight ratio of the powder with respect to polyphenylene sulfide resin 1 was knead | mixed in the pressurized kneader heated at 320 degreeC, this kneaded material was crushed into granular form, and the molding material was prepared. Polyphenylene sulfide resin and graphite were the same as in Example 1. Other parts were evaluated in the same manner as in Example 1.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Conductivity
(mΩcm)
5.5
4.5
5
6
11
3.2
6
12 Thickness nonuniformity
(μm)
± 25
± 30
± 26
± 23
± 20
± 75
± 22
± 25 Dissolution Challenge
(μS)
70
65
65
95
80
65
220
85
evaluation
Good
Good
Good Elution somewhat high, but good
Conductivity
lack
Thickness Accuracy Poor
Dissolution
Conductivity
Bad

According to the present invention, there is an effect that the productivity and durability of the fuel cell separator can be improved without causing a decrease in the mechanical properties of the fuel cell separator, poor molding, and lack of conductivity.

Moreover, when polyphenylene sulfide resin and artificial graphite are mix | blended in the ratio of 1: 2.5-1: 5 by weight ratio, the volume resistivity of the separator for fuel cells measured by a lorsta resistivity meter does not become 6 m (ohm) * cm or more, and is favorable. Electroconductivity can be obtained. In addition, deterioration in fluidity of the molding material can be suppressed, and the thickness dimension accuracy of ± 30 μm per fuel cell separator can be obtained relatively easily.

In addition, artificial graphite is prepared by mixing rod-like graphite in the bulk graphite, and when the ratio of the diameter and length of the rod-shaped graphite is 1: 3-20, the conductivity, mechanical properties, and moldability of the separator for fuel cell It is possible to satisfy the balance well. Moreover, the improvement of the bending strength of the separator for fuel cells can be expected.

In addition, by filling the lower mold of the mold with a molding material weighed approximately evenly, and scraping away the molding material of the molding portion of the mold for forming the groove, it is possible to fill the molding material without waste and with good balance. do.

Claims (5)

A method of manufacturing a separator for fuel cells, in which grooves for partitioning a flow path for fuel are formed on at least one surface of the base plate, The linear linear polyphenylene sulfide resin and powdered artificial graphite are mixed without heating so that the polyphenylene sulfide resin is not melted to prepare a molding material. The said artificial graphite is prepared by mixing rod-like graphite of a type which is not fibrous in mass graphite, The manufacturing method of the separator for fuel cells characterized by the above-mentioned.  The method of claim 1, A polyphenylene sulfide resin and artificial graphite are blended in the ratio of 1: 2.5-1: 5 by weight ratio, The manufacturing method of the separator for fuel cells characterized by the above-mentioned. The method of claim 1, A ratio of the diameter and length of said rod-shaped graphite is 1: 3-20, The manufacturing method of the separator for fuel cells characterized by the above-mentioned. The method of claim 1, A method for producing a separator for fuel cells, characterized in that the lower mold of the mold is filled with uniformly selected molding materials, and the molded materials of the molding portion of the mold for forming the grooves are scraped off. A fuel cell separator manufactured by the method for producing a fuel cell separator according to any one of claims 1 to 4, A separator for a fuel cell, wherein the volume resistivity measured by a lorsta resistivity meter is 6 mΩ · cm or less.

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