JP2002367623A - Fuel cell separator and fuel cell using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell separator with good molding property, without any problem regarding gas impermeability, electric property, liquid swelling property, mechanical strength or the like, and to provide a fuel cell with high efficiency having the above separator. SOLUTION: For the fuel cell separator having a rib part 1 and a flat part 3, the flat part 3 is formed by a layer containing the mixture of swelling graphite powder and a solid resin a, and a layer having a material with insulation property containing solid resin b, here, the melting point of the solid resin a mixed with the swelling graphite powder and the solid resin b contained in the material with insulating property are approximately same with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel cell having a rib for separating fuel gas and oxidizing gas (air or oxygen),
The present invention relates to a fuel cell separator provided with a hole (through hole) for supplying gas and water, and a fuel cell using the fuel cell separator.

[0002]

2. Description of the Related Art In recent years, fuel cells have attracted a great deal of attention from the perspective of measures to prevent global warming and energy savings due to the expansion of fossil fuel consumption, and research and development have been actively conducted at national and university research institutions and major companies. Some have been commercialized.

A fuel cell (solid polymer type) is roughly composed of an ion exchange membrane, a platinum catalyst, and a separator. Among them, the function of the separator is to quantitatively supply hydrogen and oxygen for generating energy and to quickly discharge the generated water, which is an important member that affects battery characteristics.

Since several hundred separators are used for one battery (for automobiles), it is urgent to reduce the size of the separators. At present, all separator manufacturers have improved the design of ribs, reduced the thickness and dimensional balance, and improved the weight. In addition, the company has been struggling to optimize separators, such as measures for volume reduction and cost reduction.

A conventional separator is disclosed in Japanese Patent Application Laid-Open No. 60-65.
No. 781, Japanese Patent Application Laid-Open No. 60-12672, etc., a method in which a graphite plate is used to carefully and slowly process with a high-precision cutting machine in which the shape of a rib portion and the like are programmed. It has been produced by a method in which flaky natural graphite is subjected to an acid treatment and a heat treatment, and then expanded graphite obtained by compression molding is formed into a sheet, and this sheet is impregnated with a liquid resin.

[0006] However, the separator obtained by the above method requires a long time in the rib cutting step and gas impermeability in the former case, so that the price per separator becomes very high. There is a problem in that the rib dimensions are limited and swelling is likely to occur during molding.

[0007] In order to solve the above-mentioned problems, the present inventors have developed a new molding material using a combination of pulverized powder of expanded graphite sheet and a special resin as a separator capable of forming accurate ribs at low cost and not impairing the characteristics of the fuel cell. Suggested. However, the separator molded from the above-described material has different densities between the rib portion and the flat portion, and the flat portion tends to have a low density, and has problems in gas impermeability and mechanical strength.

Further, as a measure for solving the above-mentioned problem, a molded article in which a resin-containing glass fiber is compounded in a flat portion at the time of molding has been proposed. However, the melting point and flowability of a powdery resin in a molding material (mixture) have been proposed. Since the melting point and the flowability of the powdery resin contained in the glass fiber and the glass fiber are different, the glass fiber resin flows into the rib-forming portion during molding and causes problems such as curing as it is.

[0009]

The invention according to claims 1 to 7 is directed to a fuel cell separator which is gas-impermeable,
An object of the present invention is to provide a fuel cell separator which has no problem in electric characteristics, liquid swelling property, mechanical strength and the like and has good moldability. The invention according to claims 8 and 9 provides a high-performance fuel having a fuel cell separator, which has no problem in gas impermeability, electric characteristics, liquid swellability, mechanical strength, etc., and has good moldability. A battery is provided.

[0010]

According to the present invention, there is provided a fuel cell separator having a rib portion and a flat portion, wherein the flat portion has a layer containing a mixture of expanded graphite powder and a solid resin a and an insulating material containing a solid resin b. The present invention relates to a separator for a fuel cell, comprising a layer containing a material having the following characteristics, wherein the melting point of the solid resin a mixed with the expanded graphite powder is substantially equal to the melting point of the solid resin b contained in the insulating material. Further, the present invention relates to a fuel cell separator in which a rib portion is formed of a layer containing a mixture of expanded graphite powder and solid resin a. Further, the present invention relates to a fuel cell separator in which the expanded graphite powder is a pulverized powder of an expanded graphite sheet. The present invention also relates to a fuel cell separator in which the solid resin b contained in the insulating material has a shorter gelation time than the solid resin a mixed with the expanded graphite powder.

Further, the present invention relates to a fuel cell separator having a hole in addition to a rib and a flat portion. The present invention also relates to a fuel cell separator in which the solid resin b contained in the insulating material is an epoxy resin having one or more epoxy groups that are crosslinking points.
Further, the present invention relates to a fuel cell separator in which the insulating material is a prepreg. The present invention also relates to a fuel cell having the above-mentioned separator. Furthermore, the present invention relates to the above fuel cell, which is a solid polymer type.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In a fuel cell separator according to the present invention, a rib portion has conductivity or electrical conductivity, and a gas flow path is formed when the separator is stacked via an electrolyte membrane, a fuel electrode and an air electrode. Is formed. Further, the flat portion forms a grip portion of the separator, and is configured so that gas does not leak when the gas passes through the flow path. Further, the rib portion is configured such that gas does not leak when gas passes through a flow path formed when the separators are stacked. In addition, it is preferable that the flat part be a grip part for fixing the whole when the separator is stacked.

Further, the fuel cell separator of the present invention may have a hole in addition to the rib and the flat portion, and particularly preferably has a hole in the flat portion.
The hole is configured to form a long hole in the stacking direction when many separators are stacked, and to form a hole for passing hydrogen gas, oxygen gas, and cooling water. Each hole is configured to be connected to a hydrogen gas flow path, an oxygen gas flow path, and a cooling water flow path formed by the rib portion of the separator. Note that the flat portion may have a hole for passing a fixing bolt when the separator is stacked.

It is preferable that each of the rib portion and the flat portion has a layer containing a mixture of the expanded graphite powder and the solid resin a, and these layers are continuous layers. Thereby, the moldability at the time of molding for obtaining the separator is good, the separator is given light weight, and the separator is given favorable characteristics such as high toughness and low elasticity.

In the present invention, a reinforcing layer is laminated on the flat portion as an insulating layer containing the solid resin b, and the reinforcing layer is formed of the expanded graphite powder of the flat portion and the solid resin a.
And a role of increasing the density of the layer containing the mixture of the above or improving the strength of the flat portion.

The raw material of the separator in the present invention is obtained by subjecting expanded graphite powder and solid resin a to raw materials and subjecting them to hot pressing. Among these, the expanded graphite powder is preferably an expanded graphite granulated powder obtained by granulating expanded graphite. As the expanded graphite granulated powder, a pulverized powder of an expanded graphite sheet is particularly preferable.

The expanded graphite is prepared by immersing raw graphite in a solution containing an acidic substance and an oxidizing agent to form a graphite intercalation compound, and heating the graphite intercalation compound to form a graphite crystal.
It can be manufactured by a process of expanding in the axial direction to obtain expanded graphite. The expanded graphite becomes a worm-like shape, and has a complicated entangled shape with no directionality.

The magnification of the expanded graphite is preferably high in order to ensure the strength and sealing property of the separator, and is not particularly limited, but is preferably 150 times or more, and 150 to 30 times.
More preferably, it is 0 times. The expanded graphite can be made into an expanded graphite powder by pulverizing the expanded graphite. Before the pulverization, it is preferable to apply pressure to the obtained expanded graphite and compression-mold it into a sheet to obtain an expanded graphite sheet. Further, the obtained expanded graphite powder is subjected to a treatment (such as a high-temperature treatment) for reducing acidic roots contained in the pulverized powder, if necessary.

The raw material graphite is not particularly limited, but is preferably graphite having a high degree of crystal development, such as natural graphite, quiche graphite and pyrolytic graphite. Natural graphite is preferred in consideration of the balance between the obtained characteristics and economy. The natural graphite to be used is not particularly limited.
Commercial products such as 48C (trade name, manufactured by Nippon Graphite Co., Ltd.) and H-50 (trade name, manufactured by Chuetsu Graphite Co., Ltd.) can be used.
These are preferably used in the form of scaly powder.

The acidic substances used in the processing of the raw graphite are as follows:
Generally, a material capable of penetrating between layers of graphite such as sulfuric acid to generate an acidic root (anion) having a sufficient expansion ability is used. The amount of the acidic substance to be used is not particularly limited and is determined according to the desired expansion ratio. For example, it is preferable to use 100 to 1000 parts by weight based on 100 parts by weight of graphite.

The oxidizing agent used together with the acidic substance includes peroxides such as hydrogen peroxide, potassium perchlorate, potassium permanganate and potassium dichromate, and acids having an oxidizing action such as nitric acid and hydrochloric acid. Hydrogen peroxide is particularly preferred from the viewpoint that it can be used and good expanded graphite is easily obtained. When hydrogen peroxide is used as the oxidizing agent, it is preferably used as an aqueous solution. At this time, the concentration of hydrogen peroxide is not particularly limited, but is preferably 20% by weight to 40% by weight.
Is preferred. There is no particular limitation on the amount of its use,
It is preferable to mix 5 parts by weight to 60 parts by weight of hydrogen peroxide solution with respect to 100 parts by weight of graphite.

The acidic substance and the oxidizing agent are preferably used in the form of an aqueous solution. Sulfuric acid as an acidic substance is used at an appropriate concentration, but preferably has a concentration of 95% by weight or more, and it is particularly preferable to use concentrated sulfuric acid.

In the above, there is no particular limitation on the method for producing the expanded graphite sheet, but it is generally preferable to apply pressure to the expanded graphite obtained above with a press, roll, or the like to form a sheet. There is no particular limitation on the thickness and density of the sheet when the expanded graphite is formed into a sheet.
A range of 5 mm to 1.5 mm and a density of 200 kg / m ³ to 1
Those having a range of 200 kg / m ³ are preferable. The magnitude of the density can be adjusted by adjusting the amount of pressure, the roll gap, and the like. Further, the pulverization of the expanded graphite sheet is preferably performed by coarse pulverization and fine pulverization, and thereafter, classification is performed as necessary.

In the present invention, the density of the expanded graphite powder as a raw material is not particularly limited, but is 100 kg / m ^3.
It is preferably in the range of ４００400 kg / m ³ . If the density of the expanded graphite powder is too low, the uniform mixing property with the resin tends to decrease, and the sealing property of the obtained molded article (fuel cell separator) tends to decrease. There is a tendency that the effect of improving the mechanical strength and conductivity of the molded article (separator for fuel cells) to be used is reduced.

The particle size of the expanded graphite powder is not particularly limited, but is preferably in the range of 50 μm to 300 μm in terms of number average particle size in consideration of mixability with resin and moldability. Here, when the number average particle size is less than 50 μm, the effect of entanglement of the expanded graphite powder is reduced, and the strength of the separator tends to easily decrease. On the other hand, when the thickness exceeds 300 μm, the flowability of the expanded graphite to the narrow ribs deteriorates, and it tends to be difficult to form a separator having a thin flat plate and a high rib height.

In the present invention, the solid resin a to be mixed with the expanded graphite powder is not particularly limited as long as it is a thermosetting resin. However, epoxy resin, phenol resin, melamine resin and the like are preferable in terms of cost and characteristics. In particular, phenol resins are preferable because they exhibit an excellent balance of properties and are economical and workable. The form of use of these solid resins a is preferably powdery, granular, or the like. In addition, these solid resins a
Is used, if necessary, in combination with a curing agent, a curing accelerator and the like. The form of use of the curing agent, the curing accelerator, etc. is also preferably in the form of powder, granules, or the like.

The phenolic resin has a uniform particle size as a powder property, a small amount of blocking (coagulation of powder), a small amount of gas generated during a curing reaction, easy molding, and a short heat treatment. A phenol resin having characteristics such as termination is preferred, and among them, a phenol resin containing a dihydrobenzoxazine ring polymerized by ring-opening polymerization [having a chemical structural unit represented by general formulas (A) and (B)] is preferably used. preferable.

[0028]

Embedded image (Wherein the hydrogen bonded to the aromatic ring is substituted by an alkyl group having 1 to 3 carbon atoms, a cyclohexyl group, a phenyl group or an alkyl group or an alkoxyl group having 1 to 3 carbon atoms, except for one of the ortho positions of the hydroxyl group. May be substituted by a substituted phenyl group or other hydrocarbon group).

[0029]

Embedded image (In the formula, R ¹ is a hydrocarbon group such as an alkyl group, a cyclohexyl group, a phenyl group substituted with a phenyl group or an alkyl or alkoxyl group having 1 to 3 carbon atoms of 1 to 3 carbon atoms, an aromatic ring May be substituted with a similar hydrocarbon group).

When a powdery resin is used as the solid resin a, its particle size distribution is not particularly limited. However, considering the dry mixability with the expanded graphite powder, the number average particle diameter is 1 μm to 1 μm.
A range of 00 μm is preferable, and a range of 5 μm to 50 μm is more preferable. When the number average particle size is less than 1 μm, the particles aggregate (block), and not only workability is poor, but also there is a tendency that uniform mixing with the expanded graphite powder cannot be expected. Similarly, uniform mixing with the expanded graphite powder becomes difficult, and the density of the obtained separator tends to vary greatly.

The expanded graphite powder used in the present invention and the solid resin a
Is determined in consideration of the values of various characteristics of the fuel cell separator, which is the target final molded product, and is usually expanded graphite powder / resin = 95/5 to 30/70 at the mixing ratio.
(Weight ratio) is preferable, and 90/10 to 50/50.
(Weight ratio) is more preferable, and 80/20 to 60 /
A range of 40 (weight ratio) is more preferable. Here, when the mixing ratio of the expanded graphite powder and the solid resin a exceeds 95/5, the mechanical strength tends to sharply decrease, while 30
If it is less than / 70, the amount of the expanded graphite powder that is a conductive substance is small, and the electrical characteristics tend to deteriorate.

There is no particular limitation on the method of mixing the expanded graphite powder and the solid resin a, and a shaker in which a large shearing force is not applied to the expanded graphite powder at the time of mixing in order to prevent the expansion graphite powder from being finely divided.
It is preferable to use a dry mixing method using a V blender or the like. When the expanded graphite powder is pulverized during mixing, the mechanical strength of the resulting fuel cell separator tends to sharply decrease.

The above mixture (mixed powder) can be used directly as a molding material powder. In the present invention, in order to further improve the mixing property and the workability during molding,
A sheet obtained by press-molding the mixed powder to form a sheet (hereinafter, referred to as a “sheet for molding”) is used. Although there is no particular limitation on the method of manufacturing the forming sheet, for example, a mixture tank, a gate adjuster for making the material to a constant thickness, a slitter for finishing to a constant width, a transfer device for transferring the processing material, a rolling roll for forming a sheet, and the like And an apparatus for manufacturing a sheet for molding composed of the following. When the flat portion has a hole, it is preferable that the hole is formed in the molding sheet.

In order to improve the strength of the molding sheet, the curing reaction of the resin contained in the molding sheet is partially advanced or partially (not completely) heat-fused before the production of the separator. Can be offered. Although there is no limitation on the method of curing reaction or heat melting, for example, a method of heating the obtained forming sheet, more specifically, the above-mentioned rolling roll is provided with a heating device, and this rolling roll is passed through the rolling roll. Sometimes, there is a method of heating, a method of passing the obtained molding sheet through a heating oven, and the like.

On the other hand, the solid resin b contained in the insulating material is preferably, for example, an epoxy resin in terms of cost, workability, characteristics of the obtained separator, and the like. The above epoxy resin has a melting point in terms of moldability, appearance, shape, properties, etc. of the obtained separator, and is contained in a solid resin a mixed with the expanded graphite powder, more specifically, a mixture with the expanded graphite powder constituting the molded body. It is necessary to use a material substantially equivalent to the solid resin a. In addition, the above substantially equivalent means that the difference between the melting point of the solid resin a mixed with the expanded graphite powder and the melting point of the solid resin b contained in the insulating material is up to about ± 20 ° C., preferably about ± 10 ° C. Up to

The epoxy resin is preferably an epoxy resin having at least one epoxy group which is a crosslinking point in terms of heat resistance, mechanical strength and the like. Further, the gel time of the epoxy resin is desirably 15 seconds, preferably 5 seconds shorter than the solid resin mixed with the expanded graphite powder. If the gelation time of the epoxy resin is longer than the solid resin a mixed with the expanded graphite powder, the mixture tends to flow into ribs and the like to be formed at the time of molding and harden, resulting in defective products.

Solid resin b contained in insulating material b
Is used in combination with a curing agent, a curing accelerator, and the like, if necessary. The type of epoxy resin, curing agent,
The kind of the curing accelerator and the like and the compounding amount thereof are determined by the molecular weight, melting point,
It is determined with reference to flowability, curing time and the like. The above properties,
In consideration of features, cost, storage stability, etc., the epoxy resin is preferably a bisphenol A / epichlorohydrin type epoxy resin, and particularly preferably an epoxy resin having a number average molecular weight of 900 or more.

As a curing agent used in combination with the above epoxy resin, latent dicyandiamide is preferable in consideration of storage stability, and benzyldimethylamine (BDMA) is used as a curing accelerator. The mixing ratio is preferably in the range of epoxy resin / dicyandiamide / benzyldimethylamine = 100/2 to 8/1 to 0.4 (weight ratio).

As the insulating material used in combination with the epoxy resin, a glass cloth (glass woven cloth or glass nonwoven cloth) is preferable. When this glass cloth is used as a reinforcing layer for a flat portion, it is preferable to use a prepreg obtained by impregnating the above-mentioned epoxy resin into a glass cloth and drying the resin (the degree of curing of the resin is in a B-stage state).

The glass composition of the glass cloth is not particularly limited, but C glass or E glass can be used. The fiber diameter of the glass is 3 μm to 18 μm in consideration of the mechanical strength of the obtained resin-containing glass fiber (insulating material containing the solid resin b) and the resin impregnation.
The range of μm is preferred. The glass cloth or the glass fiber as a raw material thereof is preferably subjected to a silane-based surface treatment in order to secure adhesion (sealability) with the resin, and the thickness of the glass cloth is set to 0.1.
The thickness is preferably from 15 mm to 0.33 mm, and among them, it is preferable to mainly use a plain weave as the glass woven fabric.

In the above prepreg, the resin impregnation is performed, for example, by applying a resin varnish obtained by uniformly dissolving a solid resin, a curing agent, a curing accelerator and the like in a tree-forming solvent to a woven or nonwoven fabric. be able to. The resin amount (solid content) applied to the fiber woven fabric or the nonwoven fabric is preferably 30 to 60 parts by weight, more preferably 40 to 50 parts by weight, based on the glass cloth. If the resin amount is less than 30 parts by weight, the level of gas impermeability tends to decrease,
If it exceeds 60 parts by weight, the fiber ratio tends to decrease, and the effect of reinforcing the strength of the flat portion of the separator tends to decrease.

There is no particular limitation on the form of use of the prepreg, but if a prepreg processed into the shape of a portion to be reinforced and a pre-processed sheet having the same dimensions as the forming sheet are used, the forming process can be performed. This is effective since it greatly affects the reduction of time and the improvement of the accuracy of the obtained molded body. In the case where a glass cloth having no resin on the surface is used, the surface may be coated with a resin in order to improve the adhesiveness to a molding sheet during molding.

There is no particular limitation on the molding method for obtaining the fuel cell separator according to the present invention, but it is preferable that the molding be performed by a compression molding method. The dimensions of the fuel cell separator according to the present invention are not particularly limited, and are appropriately selected according to the size of the fuel cell.

The fuel cell using the fuel cell separator of the present invention can be manufactured by a known method. The fuel cell is formed by the fuel cell separator of the present invention so as to sandwich an electrolyte layer made of a solid polymer electrolyte membrane or the like and two gas diffusion layers (made of a fuel electrode and an air electrode, carbon paper, etc.) sandwiching the electrolyte layer. The required number of cells are stacked. The fuel cell separator according to the present invention can be used as a fuel cell separator of an alkaline type, a solid polymer type, a phosphoric acid type, a molten carbonate type, a solid acid type, or the like classified according to the type of the electrolyte.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a fuel cell separator (one example) according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG. 1. 1 is a rib for securing a gas and cooling water supply path. A rib portion having (grooves), a hole portion 2 for supplying gas and cooling water, a flat portion 3, and a glass cloth prepreg 4 for reinforcing the separator.

[0046]

The present invention will be described below with reference to examples. Example 1 (1) Production of Molded Powder Mixtures of expanded graphite sheet (Carbofit HGP-105, manufactured by Hitachi Chemical Co., Ltd., trade name: 1.0 mm and density: 1000 kg / m ³ ) Pulverized by a fine pulverizer, pulverized powder of expanded graphite sheet having a number average particle diameter of 100 μm 0.7 k
g was obtained. Next, a powdery phenol resin having a dihydrobenzoxazine ring in the molecular structure and having a number average particle size of 30 μm (trade name: HR1060, manufactured by Hitachi Chemical Co., Ltd.)
Add 0.3 kg and dry mix with a small V blender.
0 kg of a mixed powder was obtained.

(2) Production of glass cloth prepreg Glass cloth cut into dimensions 200 mm × 200 mm (trade name WF230 100BS6, manufactured by Nitto Boseki Co., Ltd.)
Plain weave). On the other hand, 100 g of a powdery epoxy resin (manufactured by Ciel Chemical Co., Ltd., trade name: Epicoat 1004),
3 g of dicyandiamide (reagent) and 0.15 g of benzyldimethylamine (reagent) were slowly added to 150 g of methyl oxytol (organic solvent), and uniformly mixed to obtain a resin composition.

Thereafter, two glass cloths impregnated with the resin composition were prepared so as to have a ratio of 40 parts by weight of the resin composition and 60 parts by weight of the glass cloth per one piece of the glass cloth. Heat treatment was performed at 5 ° C. for 5 minutes to obtain a glass cloth prepreg having a thickness of 0.26 mm.

(3) Production of Fuel Cell Separator Next, a mold was prepared to obtain a fuel cell separator having the shape shown in FIGS. The lower mold has a molding surface (length, width 2)
00 mm) was a flat female mold, and the upper mold was a male mold having a projection. However, in the upper mold, the height of the protrusion is 0.5.
mm, pitch of protrusions 1.0mm, width of rib 1 1.0mm
And a rib taper of 10 degrees.

The lower mold was heated to 180 ° C., and the mixed powder (1 kg per m ² ) of 0.06 k
g was processed into a sheet shape by a roll, and one sheet for forming was placed thereon. Further, the center portion of the glass cloth prepreg 4 obtained in (2) was cut out and processed into a flat portion 3 shape. After placing one sheet, the part having the upper mold protrusion on the upper part is set downward, and then the surface pressure is set at 190 ° C. 19.
Molding was performed for 10 minutes under the conditions of ⁶ MPa (2 × 10 ⁶ kg / m ² ), and then the flat portion 3 was punched out of the hole 2 with a simple punching machine to obtain a fuel cell separator. The thickness (including the glass cloth prepreg 4) of the rib portion 1 and the flat portion 3 of the obtained fuel cell separator was 1.0 mm, and the depth of the groove of the rib portion 1 was 0.5 mm.

Comparative Example 1 (1) Production of Mixed Powder for Molding A mixed powder for molding was obtained through the same steps as (1) of Example 1. (2) Production of glass cloth prepreg Except for using (Ciel Chemical Co., Ltd., product name Epicoat 1001) as a powdery epoxy resin, a glass cloth prepreg was produced through the same blending amount and the same process as in Example 1. Obtained. (3) Production of Fuel Cell Separator A fuel cell separator was obtained through the same steps as in Example 1, (3).

Next, the appearance and gas impermeability of the fuel cell separators obtained in Example 1 and Comparative Example 1 were evaluated. Table 1 shows the results. Table 1 also shows the melting point and the gel time of the powdery epoxy resin used in Example 1 and Comparative Example 1. In Example 1 and Comparative Example 1, the melting point of the powdery phenol resin used to obtain the mixed powder for molding was 100 ° C, and the gelation time was 50 seconds (190 ° C).

The melting points shown above were measured by the Durance mercury method. Specifically, a sample weighed at 3 ± 0.005 g was placed in a standard test tube, heated and melted on an electric heater, then cooled and solidified, and 50 g of mercury was placed on the upper portion thereof, and the sample was cooled again.
The temperature was raised at a rate of ° C./min, and the temperature at which the molten sample was seen above the mercury layer was defined as the melting point. The gelation time was measured three times for each 0.2 g of sample using a gelation time measuring device (JIS C2104: hot plate method), and the average value was determined.

The appearance of the rib portion of the molded product and the interface between the rib portion and the flat portion were visually observed, and the resin component of the prepreg was slightly adhered to the rib portion. The case where it intervened was regarded as defective. As for gas impermeability (gas leakage), a flat part (including a glass cloth prepreg composite part) of a molded body was cut, and an internal pressure of 0.2 MPa was applied using a leak deactor to confirm water bubbles generated in water.

[0055]

[Table 1]

As shown in Table 1, it is apparent that the fuel cell separator of Example 1 according to the present invention is superior in appearance and gas impermeability to the fuel cell separator of Comparative Example 1. . In the fuel cell separator of Comparative Example 1, the location where the water bubbles occurred was the resin layer portion of the glass cloth prepreg at the interface between the rib portion and the flat portion.

[0057]

The fuel cell separator according to any one of claims 1 to 7 is a fuel cell separator which has no problem in gas impermeability, electric properties, liquid swelling property, mechanical strength and the like and has good moldability. is there. The fuel cell according to claims 8 and 9 is a high-performance fuel cell having a fuel cell separator which has no problem in gas impermeability, electric characteristics, liquid swelling property, mechanical strength, etc., and has good moldability. To provide.

[Brief description of the drawings]

FIG. 1 is a plan view of a fuel cell separator according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rib part 2 Hole part 3 Flat part 4 Glass cloth prepreg

Continuation of the front page (72) Inventor Ryoji Tashiro 3-3-1 Ayukawacho, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Yamazaki Office F-term (reference)

Claims (9)

[Claims] 1. A fuel cell separator having a rib portion and a flat portion, wherein the flat portion comprises a layer containing a mixture of expanded graphite powder and a solid resin a and a layer containing an insulating material containing a solid resin b. A fuel cell separator in which the melting point of the solid resin a mixed with the expanded graphite powder is substantially equal to the melting point of the solid resin b contained in the insulating material. 2. The fuel cell separator according to claim 1, wherein the rib portion comprises a layer containing a mixture of expanded graphite powder and solid resin a. 3. The fuel cell separator according to claim 1, wherein the expanded graphite powder is a pulverized powder of expanded graphite sheet. 4. The fuel cell separator according to claim 1, wherein the gelling time of the solid resin b contained in the insulating material is shorter than that of the solid resin a mixed with the expanded graphite powder. 5. The fuel cell separator according to claim 1, wherein the separator has a hole in addition to the rib portion and the flat portion. 6. A solid resin b contained in an insulating material.
Is an epoxy resin having at least one epoxy group as a cross-linking point. 7. The fuel cell separator according to claim 1, wherein the insulating material is a prepreg. 8. A fuel cell comprising the separator according to claim 1. 9. The fuel cell according to claim 8, which is of a solid polymer type.