JP4005539B2 - Manufacturing method of fuel cell separator - Google Patents

Description

【００６７】
表１に示すように、テスト１の試験片は、ポリフェニレンサルファイド（粘性６０Ｐ）を１５ｗｔ％、ポリフェニレンサルファイド（粘性２０Ｐ）を１５ｗｔ％、黒鉛（粒径１００μｍ）を６９ｗｔ％およびケッチェンブラックを１ｗｔ％含んだものである。
この混合物の流動性は、スパイラル・フロー・レシオが３０である。
【００６８】
テスト２の試験片は、ポリフェニレンサルファイド（粘性６０Ｐ）を１２．５ｗｔ％、ポリフェニレンサルファイド（粘性２０Ｐ）を１２．５ｗｔ％、可塑剤（ポリマータイプ）を２．５ｗｔ％、黒鉛（粒径１００μｍ）を６９ｗｔ％、ケッチェンブラックを１ｗｔ％およびＰＡＮ系チョップド炭素繊維を２．５ｗｔ％含んだものである。
この混合物の流動性は、スパイラル・フロー・レシオが４５である。
【００６９】
スパイラル・フロー・レシオは、スパイラル・フロー試験で求めたレシオである。スパイラル・フロー試験とは、金型に形成した狭くて長い螺旋状の溝に、射出成形機で溶融樹脂を射出し、螺旋状の溝に流入した溶融樹脂の流入長から成形性を判断する試験をいう。
【００７０】
テスト１の試験片およびテスト２の試験片の体積抵抗率を四探針法と二重リング法とで求めた。
二重リング法で求めた体積抵抗率は、テスト１が０．１５５ｍΩ・ｃｍ、テスト２が０．０７２ｍΩ・ｃｍであった。
一方、四探針法で求めた体積抵抗率は、テスト１が０．５７ｍΩ・ｃｍ、テスト２が０．３３ｍΩ・ｃｍであった。
このように、高抵抗領域に適した二重リング法で低抵抗領域の体積抵抗率を求めると、四探針法と比較してかなり低くでることが判った。そこで、信頼性を高めるために体積抵抗率を四探針法で求めることにした。
【００７１】
次に、四探針法で求めた黒鉛およびケッチェンブラックのそれぞれの含有量と体積抵抗率との関係を図６および図７で説明する。
図６は黒鉛の含有量と体積抵抗率との関係を示したグラフであり、縦軸は体積抵抗率（ｍΩ・ｃｍ）を示し、横軸は黒鉛の含有量（ｗｔ％）を示す。
黒鉛の含有量が０のとき、体積抵抗率は約１５００００ｍΩ・ｃｍであるが、黒鉛の含有量が６０ｗｔ％以上になると体積抵抗率は小さくなることが判る。
よって、黒鉛の含有量が６０ｗｔ％以上になるように、好ましくは６５ｗｔ％以上になるように設定した。
【００７２】
図７はケッチェンブラックの含有量と体積抵抗率との関係を示したグラフであり、縦軸は体積抵抗率（ｍΩ・ｃｍ）を示し、横軸はケッチェンブラックの含有量（ｗｔ％）を示す。
ケッチェンブラックの含有量が０のとき、体積抵抗率は約３４００ｍΩ・ｃｍであるが、ケッチェンブラックの含有量が１ｗｔ％になると体積抵抗率は約５００ｍΩ・ｃｍまで下がる。
【００７３】
さらに、ケッチェンブラックの含有量が２になると、体積抵抗率は約３００ｍΩ・ｃｍになり、ケッチェンブラックの含有量が３ｗｔ％になると体積抵抗率は極めて小さくなることが判る。
よって、ケッチェンブラックの含有量が１ｗｔ％以上になるように設定した。
【００７４】
次に、実施例１〜３および比較例１〜２を表２に基づいて説明する。
セパレータ１８に含有させるポリフェニレンサルファイドは、一例として出光石油化学株式会社製のものを使用し、黒鉛は、一例として日本黒鉛工業株式会社製のものを使用した。
また、ケッチェンブラックは、一例としてケッチェン・ブラック・インターナショナル株式会社製のＥＣ６００ＪＤ（商品名）を使用し、チョップド炭素繊維は、一例として東レ株式会社製のＰＡＮ系のものを使用した。
【００７５】
なお、ケッチェン・ブラック・インターナショナル株式会社製のＥＣ６００ＪＤ（商品名）は、通常のケッチェンブラックと比較して約６０％の含有量で同等の導電性を確保できる高級グレードの高導電性カーボンブラックである。
また、東レ株式会社製のチョップド炭素繊維は、直径ｄが７μｍ、長さが３ｍｍの炭素繊維である。
【００７６】
【表２】

【００７７】
表２に示すように、実施例１は、ポリフェニレンサルファイド（粘性４５Ｐ）を３３．２５ｗｔ％、黒鉛（粒径１００μｍ）を６０ｗｔ％、ケッチェンブラックを２．８５ｗｔ％、およびチョップド炭素繊維を５ｗｔ％含んだものである。なお、この混合物の流動性は、スパイラル・フロー・レシオが４０である。
【００７８】
実施例２は、ポリフェニレンサルファイド（粘性４５Ｐ）を３０ｗｔ％、黒鉛（粒径１００μｍ）を６３ｗｔ％、ケッチェンブラックを２ｗｔ％、およびチョップド炭素繊維を５ｗｔ％含んだものである。なお、この混合物の流動性は、スパイラル・フロー・レシオが４５である。
【００７９】
実施例３は、ポリフェニレンサルファイド（粘性４５Ｐ）を２５ｗｔ％、黒鉛（粒径１００μｍ）を６７ｗｔ％、ケッチェンブラックを３ｗｔ％、およびチョップド炭素繊維を５ｗｔ％含んだものである。なお、この混合物の流動性は、スパイラル・フロー・レシオが６０である。
【００８０】
比較例１は、ポリフェニレンサルファイド（粘性８０Ｐ）を３５ｗｔ％、黒鉛（粒径１００μｍ）を５８ｗｔ％、ケッチェンブラックを２ｗｔ％、およびチョップド炭素繊維を５ｗｔ％含んだものである。なお、この混合物の流動性は、スパイラル・フロー・レシオが６２である。
【００８１】
比較例２は、ポリフェニレンサルファイド（粘性８０Ｐ）を３５ｗｔ％、黒鉛（粒径１００μｍ）を６２ｗｔ％、ケッチェンブラックを３ｗｔ％含んだものである。なお、この混合物の流動性は、スパイラル・フロー・レシオが５０である。
【００８２】
実施例１〜３および比較例１〜２の試料を準備した後、図５で説明した四探針法でそれぞれの試料の体積抵抗率を求めた。
ここで、体積抵抗率が９０ｍΩ・ｃｍ以下であれば、セパレータ１８（図１参照）に採用した際に十分な導電性を確保することができるとの見通しから、体積抵抗率のしきい値を９０ｍΩ・ｃｍとし、求めた体積抵抗値が９０ｍΩ・ｃｍ以下の場合を評価○とし、求めた体積抵抗値が９０ｍΩ・ｃｍを超えた場合を評価×とした。
【００８３】
その結果、実施例１は体積抵抗率が７２ｍΩ・ｃｍと９０ｍΩ・ｃｍ以下に抑えることができたので、評価は○である。
また、実施例２は体積抵抗率が８５ｍΩ・ｃｍと９０ｍΩ・ｃｍ以下に抑えることができたので、評価は○である。
さらに、実施例３は体積抵抗率が６０ｍΩ・ｃｍと９０ｍΩ・ｃｍ以下に抑えることができたので、評価は○である。
【００８４】
一方、比較例１は体積抵抗率が３３０ｍΩ・ｃｍと９０ｍΩ・ｃｍを超えてしまうので、評価は×である。
また、比較例２は体積抵抗率が９８ｍΩ・ｃｍと９０ｍΩ・ｃｍを超えてしまうので、評価は×である。
【００８５】
なお、混合物の流動性は、成形性などを考慮すると、スパイラル・フロー・レシオで３０以上を確保する必要があり、好ましくは４０以上であることが望ましい。
実施例１〜実施例３および比較例１〜２は、混合物の流動性がスパイラル・フロー・レシオで４０以上であるので、一例として射出成形が可能であった。
【００８６】
次に、第２実施形態について説明する。
第１実施形態では、第１、第２セパレータ２０，３０に、ポリフェニレンサルファイドを１０〜３４ｗｔ％、黒鉛を６０〜８０ｗｔ％、ケッチェンブラックを１〜１０ｗｔ％、およびチョップド炭素繊維を５〜１５ｗｔ％含ませた例について説明したが、第１、第２セパレータ２０，３０に、ポリフェニレンサルファイドを１０〜３４ｗｔ％、黒鉛を６５〜８０ｗｔ％、およびケッチェンブラックを１〜１０ｗｔ％含ませることも可能である。
【００８７】
第１、第２セパレータ２０，３０にポリフェニレンサルファイドを１０〜３４ｗｔ％含ませることで、第１、第２セパレータ２０，３０を射出成形する際の成形性を高めることができるとともに、シール性に優れた第１、第２セパレータ２０，３０を得ることができる。
これにより、第１、第２セパレータ２０，３０の生産性や精度をより一層高めることができる。
【００８８】
加えて、ポリフェニレンサルファイドは耐熱性に優れた樹脂なので、第１、第２セパレータ２０，３０にポリフェニレンサルファイドを含ませることで、第１、第２セパレータ２０，３０の耐熱性を高めることができる。このため、比較的高温の領域で使用する燃料電池への適用が可能になり、用途の拡大を図ることができる。
ここで、ポリフェニレンサルファイドの含有量を１０〜３４ｗｔ％に設定した理由は、第１実施形態と同様である。
【００８９】
また、セパレータに黒鉛を６５〜８０ｗｔ％含ませることで、導電性を高めることができる。
黒鉛の含有量を６５〜８０ｗｔ％に設定した理由は、第１実施形態と同様である。
すなわち、黒鉛の含有量が６５ｗｔ％未満になると、黒鉛の含有量が少なすぎて、第１、第２セパレータ２０，３０の導電性を高めることが難しくなる。
【００９０】
一方、黒鉛の含有量が８０ｗｔ％を超えると、黒鉛の含有量が多すぎて黒鉛を均一に分散することが難しく、押出成形やプレス成形が困難になる。
そこで、熱可塑性樹脂の含有量を６５〜８０ｗｔ％に設定して、第１、第２セパレータ２０，３０の導電性を確保するとともに、成形性を確保することにした。
【００９１】
また、黒鉛の含有量を６５ｗｔ％以上に確保することで、第１、第２セパレータ２０，３０の体積抵抗率（ｍΩ・ｃｍ）を低減させて、第１、第２セパレータ２０，３０の導電性を十分に高めることができる。
【００９２】
さらに、セパレータにケッチェンブラックを１〜１０ｗｔ％含ませることで、導電性をより一層高めることができる。
ケッチェンブラックの含有量を１〜１０ｗｔ％に設定した理由は、第１実施形態と同様である。
第２実施形態の第１、第２セパレータ２０，３０によれば、第１実施形態と同様の効果を得ることができる。
【００９３】
なお、前記実施形態の第１、第２セパレータ２０，４０は、押出し成形やプレス成形で連続的に成形することが可能であり、さらに加熱プレス方法、射出成形方法やトランスファー成形方法などの製造方法で成形することが可能である。
トランスファー成形方法とは、成形材料をキャビティとは別のポット部に１ショット分入れ、プランジャーによって溶融状態の材料をキャビティに移送して成形する方法である。
【００９４】
また、前記実施形態では、第１、第２セパレータ２０，３０に含ませたポリフェニレンサルファイドの粘性を２０〜８０Ｐに設定した例について説明したが、ポリフェニレンサルファイドの粘性が８０Ｐより高い場合には、可塑剤を使用して対応することも可能である。
【００９５】
さらに、前記実施形態では、粒径が１００μｍの黒鉛を使用する例について説明したが、黒鉛の粒径は１００μｍに限るものではなく、その他の粒径を使用することも可能である。
【００９６】
加えて、前記実施形態では、ケッチェンブラックを、一例としてケッチェン・ブラック・インターナショナル株式会社製（販売元；三菱化学株式会社）の「ＥＣ６００ＪＤ」を使用した例について説明したが、これに限らないで、例えばケッチェン・ブラック・インターナショナル株式会社製の「ＥＣ」を使用することも可能であり、その他のケッチェンブラックを使用することも可能である。
さらに、ケッチェンブラックと同様に導電性に優れたカーボンブラックであれば、ケッチェンブラックに代えて使用することも可能である。
【００９７】
また、前記実施形態では、ＰＡＮ系のチョップド炭素繊維を使用する例について説明したが、これに限らないで、例えばピッチ系のチョップド炭素繊維を使用することも可能である。
【００９８】
【発明の効果】
本発明は上記構成により次の効果を発揮する。
請求項１は、燃料電池用セパレータの素材に、メルトマスフローレイト試験方法における粘性が２０〜８０Ｐのポリフェニレンサルファイドを１０〜３４ｗｔ％、黒鉛を６５〜８０ｗｔ％、およびケッチェンブラックを１〜１０ｗｔ％含んだ混合物を用い、この混合物の流動性をスパイラル・フロー・レシオで３０を超える値に設定して成形したので、セパレータを射出成形する際の成形性を高めることができる。これにより、セパレータの生産性や精度をより一層高めることができる。
【００９９】
加えて、ポリフェニレンサルファイドは耐熱性に優れた樹脂なので、セパレータにポリフェニレンサルファイドを含ませることで、セパレータの耐熱性を高めることができる。このため、比較的高温の領域で使用する燃料電池への適用が可能になり、用途の拡大を図ることができる。
そこで、ポリフェニレンサルファイドの含有量を１０〜３４ｗｔ％に設定して、セパレータの成形性、シール性、耐熱性や結合性を確保するとともに、十分な導電性を確保することにした。
【０１００】
また、黒鉛の含有量を６５〜８０ｗｔ％に設定して、セパレータの導電性を確保するとともに、成形性を確保することにした。
さらに、黒鉛の含有量を６５ｗｔ％以上に確保することで、セパレータの体積抵抗率を低減させて、セパレータの導電性を十分に高めることができる。
加えて、セパレータにケッチェンブラックを１〜１０ｗｔ％含ませることで、導電性をより一層高めることができる。
【０１０１】
請求項２は、燃料電池用セパレータの素材に、メルトマスフローレイト試験方法における粘性が２０〜８０Ｐのポリフェニレンサルファイドを１０〜３４ｗｔ％、黒鉛を６０〜８０ｗｔ％、ケッチェンブラックを１〜１０ｗｔ％、およびチョップド炭素繊維を５〜１５ｗｔ％含んだ混合物を用い、この混合物の流動性をスパイラル・フロー・レシオで３０を超える値に設定して成形することで、燃料電池用セパレータの成形性をより一層高めることができる。加えてセパレータの強度や耐熱性を高めることができる。
【０１０２】
【図面の簡単な説明】
【図１】 本発明に係る燃料電池用セパレータの製造方法で製造した燃料電池用セパレータを燃料電池に使用した例を示す分解斜視図である。
【図２】 図１のＡ−Ａ線断面図
【図３】 図１のＢ−Ｂ線断面図
【図４】 本発明に係る燃料電池用セパレータを示す断面図
【図５】 体積抵抗率の求め方を説明した図
【図６】 黒鉛の含有量と体積抵抗率との関係を示したグラフ
【図７】 ケッチェンブラックの含有量と体積抵抗率との関係を示したグラフ
【符号の説明】
１０…燃料電池、１２…電解質膜、１３…アノード側電極、１４…カソード側電極、１５…アノード側電極拡散層（拡散層）、１６…カソード側電極拡散層（拡散層）、１８…セパレータ（燃料電池用セパレータ）、２０…第１セパレータ、３０…第２セパレータ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell separator that constitutes a cell module by attaching an anode side electrode and a cathode side electrode to an electrolyte membrane and sandwiching them from both sides Manufacturing method About.
[0002]
[Prior art]
As a composition of a separator for a fuel cell, a composition in which carbon fiber or carbon nanotube is blended with a thermoplastic resin is known (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP 2002-97375 A (page 9, FIG. 1)
[0004]
The contents of Patent Document 1 will be described in detail.
Here, when the separator is incorporated in the fuel cell, it is necessary to form a plurality of grooves for gas flow paths and grooves for cooling water flow paths on both surfaces thereof. For this reason, it is necessary to use the separator material having excellent moldability.
In addition, the separator is required to have a function of collecting current from the electrodes and needs to be excellent in conductivity.
[0005]
In order to satisfy this requirement, in Patent Document 1, polyphenylene sulfide (thermoplastic resin) excellent in moldability is used as the separator composition, and carbon fibers and carbon nanotubes excellent in conductivity are used. It was to be.
An example will be described in detail. 30% by weight of carbon fibers, 0.5% by weight of carbon nanotubes, and 69.5% by weight of polyphenylene sulfide (thermoplastic resin) were prepared as a separator composition, and these were mixed to obtain a mixture. . Thereafter, a separator was injection molded from this mixture.
[0006]
By using 69.5 wt% of polyphenylene sulfide which is a thermoplastic resin, injection moldability can be secured. Furthermore, by using 30 wt% of carbon fiber and 0.5 wt% of carbon nanotube, a certain degree of conductivity can be ensured.
[0007]
[Problems to be solved by the invention]
However, since the technology of Patent Document 1 contains a large amount of carbon fiber in the material, the orientation of the carbon fiber is remarkably generated and the separator becomes anisotropic. Therefore, the separator may be warped or deformed.
In addition, when there are a gas channel groove or a cooling water channel groove on both sides like a separator, a weld line is easily formed. For this reason, there exists a possibility that the intensity | strength of a separator may fall extremely and may be damaged.
[0008]
Furthermore, in the technique of Patent Document 1, carbon fiber or carbon nanotube is included in the separator material in order to increase the conductivity of the separator. However, even if carbon fiber is contained in the separator material, it is difficult to sufficiently increase the conductivity.
Specifically, in Patent Document 1, the volume resistivity is measured by a double ring method (ASTM D257). However, the double ring method is suitable for the measurement of the high resistance region, and the measurement results of the present inventors show that the volume resistivity is considerably lower than the four-probe method suitable for the measurement of the low resistance region. I understood.
In addition, in recent years, fuel cells have been required to have high performance, and in order to satisfy this requirement, it has been desired to put a separator having better conductivity into practical use.
[0009]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to increase the strength and to provide a fuel cell separator with excellent conductivity. Manufacturing method Is to provide.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, claim 1 is a method for manufacturing a fuel cell separator in which an anode side electrode and a cathode side electrode along an electrolyte membrane are sandwiched from both sides through a diffusion layer. The viscosity in the melt mass flow rate test method is 20-80. P A mixture containing 10 to 34 wt% of polyphenylene sulfide, 65 to 80 wt% of graphite, and 1 to 10 wt% of ketjen black was used, and the fluidity of this mixture was set to a value exceeding 30 in the spiral flow ratio. It is characterized by molding.
[0011]
The separator contained 10 to 34 wt% of polyphenylene sulfide as a thermoplastic resin. Since polyphenylene sulfide is a resin excellent in moldability and elasticity, it is possible to improve the moldability when the separator is injection-molded and to obtain a separator excellent in sealability.
[0012]
In addition, since polyphenylene sulfide is a resin excellent in heat resistance, the heat resistance of the separator can be increased by including polyphenylene sulfide in the separator. For this reason, application to a fuel cell used in a relatively high temperature region becomes possible.
[0013]
Here, the reason why the content of polyphenylene sulfide is set to 10 to 34 wt% is as follows.
When the content of polyphenylene sulfide is less than 10 wt%, the content of polyphenylene sulfide is too small, and it becomes difficult to ensure the moldability of the separator and the elasticity of the contact surface of the separator, that is, the sealing performance.
Furthermore, when the content is less than 10 wt%, it is difficult to ensure the heat resistance of the separator and to exert its function as a binder.
[0014]
On the other hand, when the content of polyphenylene sulfide exceeds 34 wt%, the content of graphite contained in the separator decreases, and it becomes difficult to sufficiently secure the conductivity of the separator.
Therefore, the content of polyphenylene sulfide was set to 10 to 34 wt%.
[0015]
Furthermore, electroconductivity can be improved by making a separator contain 65-80 wt% of graphite.
The reason why the graphite content is set to 65 to 80 wt% is as follows.
When the graphite content is less than 65 wt%, the graphite content is too small, and it becomes difficult to increase the conductivity of the separator.
[0016]
On the other hand, if the graphite content exceeds 80 wt%, it is difficult to uniformly disperse graphite because the graphite content is too high, and extrusion molding and press molding become difficult.
Therefore, the content of the thermoplastic resin was set to 65 to 80 wt%.
Moreover, by ensuring the graphite content to 65 wt% or more, the volume resistivity of the separator can be reduced and the conductivity of the separator can be sufficiently increased.
[0017]
In addition, the conductivity can be further increased by including 1 to 10 wt% of ketjen black in the separator.
Ketjen black is a member that is particularly excellent in conductivity compared to other carbon blacks, and the conductivity of the separator can be further enhanced by including ketjen black in the separator.
[0018]
Here, the reason for setting the ketjen black content to 1 to 10 wt% is as follows.
If the ketjen black content is less than 1 wt%, the ketjen black content may be too small to ensure sufficient conductivity of the separator.
[0019]
On the other hand, when the content of ketjen black exceeds 10 wt%, the content of ketjen black is too high and kneading becomes difficult. Although it may be possible to knead by adding a solvent, the use of a solvent may increase the cost.
In addition, even when a solvent is added and kneaded, the kneaded material containing ketjen black has relatively poor fluidity, and it is difficult to obtain a predetermined shape during molding, for example.
Therefore, the content of ketjen black was set to 1 to 10 wt%.
[0020]
Further, graphite and ketjen black contained in the separator are carbon particles, and the fibrous material is not contained in the separator in a large amount. Therefore, it is possible to suppress the occurrence of orientation in the separator due to the fibrous substance, and it is possible to prevent the separator from being warped or deformed due to anisotropy.
[0021]
Furthermore, since the separator does not contain a large amount of fibrous material, it prevents a weld line from being generated in the gas channel groove or the cooling water channel groove provided in the separator, thereby reducing the strength of the separator. be able to.
The fuel cell separator material has a viscosity of 20-80 in the melt mass flow rate test method. P A mixture containing 10 to 34 wt% of polyphenylene sulfide, 65 to 80 wt% of graphite, and 1 to 10 wt% of ketjen black was used, and the fluidity of this mixture was set to a value exceeding 30 in the spiral flow ratio. By molding, the moldability of the fuel cell separator can be further enhanced.
[0022]
According to a second aspect of the present invention, there is provided a method for manufacturing a fuel cell separator in which an anode side electrode and a cathode side electrode along an electrolyte membrane are sandwiched from both sides via a diffusion layer. Viscosity is 20-80 P A mixture of 10 to 34 wt% polyphenylene sulfide, 60 to 80 wt% graphite, 1 to 10 wt% ketjen black, and 5 to 15 wt% chopped carbon fiber. The molding is characterized in that the ratio is set to a value exceeding 30.
[0023]
By including 10 to 34 wt% of polyphenylene sulfide, 60 to 80 wt% of graphite, and 1 to 10 wt% of ketjen black in the separator, the same effect as in claim 1 can be obtained.
In addition, the strength and heat resistance of the separator can be increased by including 5 to 15 wt% of chopped carbon fiber in the separator.
Furthermore, when the chopped carbon fiber is included in the separator, this assumes a part of the function of graphite, so the lower limit of the graphite content may be 60 wt%.
[0024]
Here, the reason why the content of the chopped carbon fiber is set to 5 to 15 wt% is as follows.
If the content of chopped carbon fiber is less than 5 wt%, the content of chopped carbon fiber is too small, and it becomes difficult to ensure the strength and heat resistance of the separator.
[0025]
On the other hand, when the content of the chopped carbon fiber exceeds 15 wt%, the content of the chopped carbon fiber included in the separator is too large, and the orientation of the chopped carbon fiber is remarkably generated, so that the separator becomes anisotropic. Therefore, the separator may be warped or deformed.
[0026]
In addition, when there are a gas channel groove or a cooling water channel groove on both sides like a separator, a weld line is easily formed. For this reason, there exists a possibility that the intensity | strength of a separator may fall extremely and may be damaged.
Therefore, the content of chopped carbon fiber was set to 5 to 15 wt%.
The fuel cell separator material has a viscosity of 20-80 in the melt mass flow rate test method. P (Poise) A mixture of 10 to 34 wt% polyphenylene sulfide, 60 to 80 wt% graphite, 1 to 10 wt% ketjen black, and 5 to 15 wt% chopped carbon fiber. By forming the ratio at a value exceeding 30, the moldability of the fuel cell separator can be further enhanced.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 relates to the present invention. Manufactured with a method for manufacturing a fuel cell separator Fuel cell separator Burn Battery Example used for FIG.
As an example, the fuel cell 10 uses a solid polymer electrolyte for the electrolyte membrane 12, the anode side electrode 13 and the cathode side electrode 14 are attached to the electrolyte membrane 12, and the anode side electrode diffusion layer 15 is provided on the anode side electrode 13 side. The cell module 11 is configured by aligning the separator 18 via the cathode side electrode 14 and the separator (fuel cell separator) 18 via the cathode side electrode diffusion layer 16 on the cathode side electrode 14 side. This is a solid polymer fuel cell.
[0028]
The separator 18 includes a first separator 20 and a second separator 30, and is formed by joining the cooling water passage forming surface 20 a of the first separator 20 and the joining surface 30 a of the second separator 30.
[0029]
Thus, by joining the first and second separators 20 and 30, the cooling water passage grooves 21 of the first separator 20 are covered with the second separator 30, and the cooling water passage 22 (shown in FIG. 4). Form.
The cooling water passages 22... Communicate with cooling water supply holes 23 a and 33 a at the center of the upper ends of the first and second separators 20 and 30, and the cooling water at the center of the lower ends of the first and second separators 20 and 30. The discharge holes 23b and 33b communicate with each other.
[0030]
The first separator 20 includes fuel gas passage grooves 24 (shown in FIG. 2) on the fuel gas passage forming surface 20b side, and the anode-side electrode diffusion layer 15 is overlapped on the fuel gas passage forming surface 20b, thereby The gas passage grooves 24 are closed by the anode side electrode diffusion layer 15 to form fuel gas passages 25 (shown in FIG. 4).
The fuel gas passages 25... Communicate with the fuel gas supply holes 26 a, 36 a on the left side of the upper ends of the first and second separators 20, 30 and discharge the fuel gas on the right side of the lower ends of the first and second separators 20, 30. The holes 26b and 36b are communicated.
[0031]
The second separator 30 includes oxidant gas passage grooves 37 on the oxidant gas passage formation surface 30b side, and the cathode side electrode diffusion layer 16 is overlaid on the oxidant gas passage formation surface 30b, whereby the oxidant gas passage is formed. The grooves 37 are closed by the cathode side electrode diffusion layer 16 to form oxidant gas passages 38 (shown in FIG. 4).
The oxidant gas passages 38... Communicate with the oxidant gas supply holes 29 a and 39 a on the right side of the upper ends of the first and second separators 20 and 30, and the oxidation on the left side of the lower ends of the first and second separators 20 and 30. The agent gas discharge holes 29b and 39b communicate with each other.
[0032]
The first and second separators 20 and 30 were formed of a mixture containing 10 to 34 wt% polyphenylene sulfide, 60 to 80 wt% graphite, 1 to 10 wt% ketjen black, and 5 to 15 wt% chopped carbon fiber. Is.
[0033]
The first and second separators 20 and 30 contained 10 to 34 wt% of polyphenylene sulfide as a thermoplastic resin. Since polyphenylene sulfide is a resin excellent in moldability and elasticity, it is possible to improve the moldability when the first and second separators 20 and 30 are injection molded, and the first and second excellent in sealability. Two separators 20 and 30 can be obtained.
Thereby, the productivity and accuracy of the first and second separators 20 and 30 can be further enhanced.
[0034]
In addition, since polyphenylene sulfide is a resin having excellent heat resistance, the heat resistance of the first and second separators 20 and 30 can be increased by including the polyphenylene sulfide in the first and second separators 20 and 30.
For this reason, it can be applied to a fuel cell used in a relatively high temperature region, and the use can be expanded.
[0035]
Here, the reason why the content of polyphenylene sulfide is set to 10 to 34 wt% is as follows.
When the content of polyphenylene sulfide is less than 10 wt%, the content of polyphenylene sulfide is too small, and the moldability of the first and second separators 20 and 30 and the elasticity of the contact surfaces of the first and second separators 20 and 30 are reduced. That is, it becomes difficult to ensure sealing performance.
Furthermore, when the content is less than 10 wt%, it is difficult to ensure the heat resistance of the first and second separators 20 and 30 and to exert their function as a binder.
[0036]
On the other hand, when the content of polyphenylene sulfide exceeds 34 wt%, the content of graphite contained in the first and second separators 20 and 30 decreases, and the conductivity of the first and second separators 20 and 30 is sufficiently ensured. It becomes difficult.
Therefore, the content of the thermoplastic resin is set to 10 to 34 wt% to ensure the moldability, sealability, heat resistance and bonding properties of the first and second separators 20 and 30 and ensure sufficient conductivity. Decided to do.
[0037]
Furthermore, electroconductivity can be improved by making the 1st, 2nd separators 20 and 30 contain 60-80 wt% of graphite.
The reason why the content of graphite is set to 60 to 80 wt% is as follows.
When the graphite content is less than 60 wt%, the graphite content is too small, and it becomes difficult to increase the conductivity of the first and second separators 20 and 30.
[0038]
On the other hand, if the graphite content exceeds 80 wt%, it is difficult to uniformly disperse graphite because the graphite content is too high, and extrusion molding and press molding become difficult.
Therefore, the content of the thermoplastic resin is set to 60 to 80 wt% to ensure the conductivity of the first and second separators 20 and 30 and to ensure the moldability.
[0039]
Further, by ensuring that the graphite content is 60 wt% or more, the volume resistivity (mΩ · cm) of the first and second separators 20 and 30 is reduced, and the conductivity of the first and second separators 20 and 30 is reduced. The sex can be enhanced sufficiently.
[0040]
On the other hand, when the content of polyphenylene sulfide exceeds 34 wt%, the content of graphite contained in the first and second separators 20 and 30 decreases, and the conductivity of the first and second separators 20 and 30 is sufficiently ensured. It becomes difficult.
Therefore, the content of the thermoplastic resin is set to 10 to 34 wt% to ensure the moldability, sealability, heat resistance and bonding properties of the first and second separators 20 and 30 and ensure sufficient conductivity. Decided to do.
[0041]
In addition, by including 1 to 10 wt% of ketjen black in the first and second separators 20 and 30, the conductivity can be further enhanced.
Ketjen black is a member that is particularly excellent in conductivity as compared with other carbon blacks. By including ketjen black in the first and second separators 20 and 30, the first and second separators 20 and 30 are used. The electrical conductivity of can be further increased.
[0042]
Here, the reason for setting the ketjen black content to 1 to 10 wt% is as follows.
If the ketjen black content is less than 1 wt%, the ketjen black content may be too small to sufficiently ensure the conductivity of the first and second separators 20 and 30.
[0043]
On the other hand, when the content of ketjen black exceeds 10 wt%, the content of ketjen black is too large and it becomes difficult to knead. Although it may be possible to knead by adding a solvent, the use of a solvent may increase the cost.
In addition, even if the solvent can be added and kneaded, the kneaded material containing ketjen black has relatively poor fluidity, and it is difficult to obtain a predetermined shape during molding, for example.
Therefore, by setting the ketjen black content to 1 to 10 wt%, the first and second separators 20 and 30 have sufficient conductivity, further facilitate kneading and have good moldability. Decided to secure.
[0044]
The graphite and ketjen black contained in the first and second separators 20 and 30 are carbon particles, and the separator does not contain a large amount of fibrous material. Therefore, it is possible to suppress the occurrence of orientation in the separator due to the fibrous material, and to prevent the first and second separators 20 and 30 from being warped or deformed due to anisotropy.
[0045]
In addition, since the first and second separators 20 and 30 do not contain a large amount of fibrous material, the first and second separators 20 and 30 are provided with gas channel grooves or cooling water channel grooves. It is possible to prevent the weld lines from being generated and the strength of the first and second separators 20 and 30 from being lowered.
[0046]
In addition, the strength and heat resistance of the first and second separators 20 and 30 can be increased by including 5 to 15 wt% of chopped carbon fibers in the first and second separators 20 and 30.
[0047]
Here, the reason why the content of the chopped carbon fiber is set to 5 to 15 wt% is as follows.
If the content of the chopped carbon fiber is less than 5 wt%, the content of the chopped carbon fiber is too small, and it becomes difficult to ensure the strength and heat resistance of the first and second separators 20 and 30.
[0048]
On the other hand, when the content of the chopped carbon fiber exceeds 15 wt%, the content of the chopped carbon fiber included in the first and second separators 20 and 30 is too large, and the orientation of the chopped carbon fiber is remarkably generated. The second separators 20 and 30 become anisotropic. Therefore, the first and second separators 20 and 30 may be warped or deformed.
[0049]
In addition, when there are a gas channel groove or a cooling water channel groove on both sides like the first and second separators 20 and 30, a weld line is easily formed. For this reason, there exists a possibility that the intensity | strength of the 1st, 2nd separator 20 and 30 may fall extremely and may be damaged.
Therefore, the strength and durability of the first and second separators 20 and 30 are secured by setting the content of chopped carbon fiber to 5 to 15 wt%.
[0050]
Here, the polyphenylene sulfide contained in the first and second separators 20 and 30 has a viscosity of 20 to 80. P (Poise) Is set.
[0051]
Polyphenylene sulfide viscosity of 20-80 P The reason for setting is as follows.
The viscosity of polyphenylene sulfide is 20 P If it is less than this, the viscosity is too low, and the polyphenylene sulfide does not solidify during the production of the first and second separators 20 and 30 and becomes a slurry.
[0052]
On the other hand, the viscosity of polyphenylene sulfide is 80 P If it exceeds 1, the viscosity of the polyphenylene sulfide is too high, and graphite or the like cannot be kneaded well in the polyphenylene sulfide when the first and second separators 20 and 30 are manufactured.
Therefore, the viscosity of polyphenylene sulfide is 20-80. P By setting to, graphite and the like can be kneaded well with polyphenylene sulfide, thereby further improving the moldability of the separator.
[0053]
The viscosity of polyphenylene sulfide was measured at 300 ° C. by the MFR (melt mass flow rate) test method (ASTM D1238).
Here, MFR means that a polymetal sulfide is filled in a vertical metal cylinder, and this polyphenylene sulfide is pushed by a piston with a weight and pushed out from a die at the tip of the cylinder. Is a method of measuring the viscosity and obtaining the viscosity based on the measured value.
[0054]
2 is a cross-sectional view taken along line AA in FIG.
The first separator 20 is a member formed in a substantially rectangular shape as shown in FIG. 1, and includes a plurality of cooling water passage grooves 21 on the cooling water passage forming surface 20a, and a fuel gas passage forming surface (contact surface) 20b. Are provided with a number of fuel gas passage grooves 24.
[0055]
The first separator 20 contained 10 to 34 wt% of polyphenylene sulfide. Thereby, while ensuring the moldability of the 1st separator 20, sealing performance, heat resistance, and bondability, sufficient electroconductivity can be ensured.
[0056]
Here, since the chopped carbon fiber included in the first separator 20 has a high elastic modulus, if the content of the chopped carbon fiber is too large, the inside of the rib 40 forming the cooling water passage groove 21. The chopped carbon fibers do not completely enter the ribs 41 forming the grooves 24, and separation between the chopped carbon fibers and polyphenylene sulfide easily occurs.
[0057]
For this reason, the ribs 40... 41... Have a higher polyphenylene sulfide content than other sites, and may not be able to exhibit their original performance.
Therefore, the content of chopped carbon fiber was suppressed to 5 to 15 wt%. Accordingly, the chopped carbon fibers can be suitably inserted into the ribs 40, 41, and the ribs 40, 41, ... can be formed satisfactorily.
[0058]
3 is a cross-sectional view taken along line BB in FIG.
The second separator 30 is a member formed in a substantially rectangular shape as shown in FIG. 1, and has a joining surface 30a formed flat, and an oxidizing gas passage groove 37 on the oxidizing gas passage forming surface (contact surface) 30b. A lot of this article.
[0059]
The second separator 30 contained 10 to 34 wt% of polyphenylene sulfide. Thereby, while ensuring the moldability of the 1st separator 20, sealing performance, heat resistance, and bondability, sufficient electroconductivity can be ensured.
Here, similarly to the first separator 20, the second separator 30 also has the chopped carbon fiber content of 5 to 15 wt%. Can be formed satisfactorily.
[0060]
FIG. 4 is a cross-sectional view showing a fuel cell separator according to the present invention.
The separator 18 joins the cooling water passage forming surface 20a of the first separator 20 and the joining surface 30a of the second separator 30, and cools the cooling water passage groove 21 of the first separator 20 with the second separator 30. A water passage 22 is formed.
By aligning the anode side electrode diffusion layer 15 with the fuel gas passage formation surface 20 b, the fuel gas passages 25 are formed by the fuel gas passage grooves 24 and the anode side electrode diffusion layer 15.
[0061]
Since this separator 18 contains 5 to 15 wt% of chopped carbon fibers, the strength, elastic modulus, and heat resistance can be further improved. Increasing the strength of the separator 18 can increase the tightening strength when the separator 18 is incorporated into the fuel cell.
Further, by increasing the elastic modulus and heat resistance of the separator 18, the gas pressure resistance and creep strength at high temperatures can be increased, so that the fuel cell can be suitably used even in a high temperature region.
[0062]
Next, in FIG. 5, how to obtain the volume resistivity ρv will be described.
FIG. 5 is a diagram for explaining how to obtain the volume resistivity, and an example in which the volume resistivity ρv of the sample 50 (width W, height t, length L) is obtained by the four-probe method (ASTM D991). Will be described.
A constant current I is allowed to flow from one end 51 having a cross-sectional area (W × t) to the other end 52 as indicated by an arrow, and a potential difference V between the electrode on the one end 51 side and the electrode on the other end 52 side separated by a distance L is obtained. Measure with the four-probe method.
Based on the measured potential difference V, the volume resistivity ρv is obtained by the following equation.
Volume resistivity ρv = (V / I) × (W / L) × t
[0063]
Here, the reason why the four-point probe method is adopted will be described.
When measuring the potential difference V, if a constant current I of the sample 50 is passed, a voltage drop called contact resistance is generated between the one end 51 of the sample 50 and the current electrode due to an interface phenomenon. The resistance Ω (V / I) is measured high due to the influence of the contact resistance.
[0064]
Therefore, by adopting the four-point probe method, the contact resistance can be eliminated and the true volume resistivity ρv of the sample 50 can be obtained.
In addition to the four probe method, a double ring method (ASTM D257) is also known as a method for measuring the potential difference V.
[0065]
However, the double ring method is suitable for the measurement of the high resistance region, and the measurement result of the present inventor has also shown that the volume resistivity is considerably lower than that of the four probe method.
Hereinafter, the volume resistivity determined by the four-probe method (ASTM D991) and the double ring method (ASTM D257) based on Table 2 will be described.
[0066]
[Table 1]

[0067]
As shown in Table 1, the test piece of Test 1 was polyphenylene sulfide (viscosity 60 P 15 wt%, polyphenylene sulfide (viscosity 20) P ) 15 wt%, graphite (particle size 100 μm) 69 wt% and ketjen black 1 wt%.
The fluidity of this mixture is a spiral flow ratio of 30.
[0068]
The test piece of test 2 was polyphenylene sulfide (viscosity 60 P 12.5 wt%, polyphenylene sulfide (viscosity 20) P 12.5 wt%, plasticizer (polymer type) 2.5 wt%, graphite (particle size 100 μm) 69 wt%, ketjen black 1 wt% and PAN chopped carbon fiber 2.5 wt% is there.
The fluidity of this mixture is a spiral flow ratio of 45.
[0069]
The spiral flow ratio is a ratio obtained by a spiral flow test. The spiral flow test is a test in which the molten resin is injected into the narrow and long spiral groove formed in the mold by an injection molding machine, and the moldability is judged from the inflow length of the molten resin flowing into the spiral groove. Say.
[0070]
The volume resistivity of the test piece of test 1 and the test piece of test 2 was determined by the four-probe method and the double ring method.
The volume resistivity determined by the double ring method was 0.155 mΩ · cm for test 1 and 0.072 mΩ · cm for test 2.
On the other hand, the volume resistivity determined by the four-point probe method was 0.57 mΩ · cm for test 1 and 0.33 mΩ · cm for test 2.
Thus, when the volume resistivity of the low resistance region was obtained by the double ring method suitable for the high resistance region, it was found that the volume resistivity was considerably lower than that of the four probe method. Therefore, in order to increase the reliability, the volume resistivity was determined by the four probe method.
[0071]
Next, the relationship between the respective contents of graphite and ketjen black obtained by the four-probe method and the volume resistivity will be described with reference to FIGS.
FIG. 6 is a graph showing the relationship between the graphite content and the volume resistivity. The vertical axis represents the volume resistivity (mΩ · cm), and the horizontal axis represents the graphite content (wt%).
When the graphite content is 0, the volume resistivity is about 150,000 mΩ · cm, but it can be seen that the volume resistivity decreases when the graphite content exceeds 60 wt%.
Therefore, the graphite content is set to 60 wt% or more, preferably 65 wt% or more.
[0072]
FIG. 7 is a graph showing the relationship between the ketjen black content and the volume resistivity. The vertical axis represents the volume resistivity (mΩ · cm), and the horizontal axis represents the ketjen black content (wt%). Indicates.
When the ketjen black content is 0, the volume resistivity is about 3400 mΩ · cm, but when the ketjen black content is 1 wt%, the volume resistivity decreases to about 500 mΩ · cm.
[0073]
Further, it can be seen that when the ketjen black content is 2, the volume resistivity is about 300 mΩ · cm, and when the ketjen black content is 3 wt%, the volume resistivity is extremely small.
Therefore, the ketjen black content was set to 1 wt% or more.
[0074]
Next, Examples 1-3 and Comparative Examples 1-2 will be described based on Table 2.
The polyphenylene sulfide contained in the separator 18 is, for example, that manufactured by Idemitsu Petrochemical Co., Ltd., and the graphite is, for example, that manufactured by Nippon Graphite Industries, Ltd.
As an example, Ketjen Black used EC600JD (trade name) manufactured by Ketjen Black International Co., Ltd., and chopped carbon fiber used as a PAN manufactured by Toray Industries, Inc. as an example.
[0075]
In addition, EC600JD (trade name) manufactured by Ketjen Black International Co., Ltd. is a high-grade high-conductivity carbon black that can ensure equivalent conductivity at a content of about 60% compared to normal Ketjen Black. is there.
The chopped carbon fiber manufactured by Toray Industries, Inc. is a carbon fiber having a diameter d of 7 μm and a length of 3 mm.
[0076]
[Table 2]

[0077]
As shown in Table 2, Example 1 is polyphenylene sulfide (viscosity 45 P ) 33.25 wt%, graphite (particle size 100 μm) 60 wt%, ketjen black 2.85 wt%, and chopped carbon fiber 5 wt%. The fluidity of this mixture is 40 in the spiral flow ratio.
[0078]
Example 2 is polyphenylene sulfide (viscosity 45 P ) 30 wt%, graphite (particle size 100 μm) 63 wt%, ketjen black 2 wt%, and chopped carbon fiber 5 wt%. The fluidity of this mixture is 45 in the spiral flow ratio.
[0079]
Example 3 is polyphenylene sulfide (viscosity 45 P ) 25 wt%, graphite (particle size 100 μm) 67 wt%, ketjen black 3 wt%, and chopped carbon fiber 5 wt%. The fluidity of this mixture is 60 in the spiral flow ratio.
[0080]
Comparative Example 1 is polyphenylene sulfide (viscosity 80 P ) 35 wt%, graphite (particle size 100 μm) 58 wt%, ketjen black 2 wt%, and chopped carbon fiber 5 wt%. The fluidity of this mixture is a spiral flow ratio of 62.
[0081]
Comparative Example 2 is polyphenylene sulfide (viscosity 80 P ) 35 wt%, graphite (particle size 100 μm) 62 wt%, and ketjen black 3 wt%. The fluidity of this mixture is 50 in the spiral flow ratio.
[0082]
After preparing the samples of Examples 1 to 3 and Comparative Examples 1 and 2, the volume resistivity of each sample was determined by the four-probe method described in FIG.
Here, if the volume resistivity is 90 mΩ · cm or less, the threshold value of the volume resistivity is set from the perspective that sufficient conductivity can be secured when employed in the separator 18 (see FIG. 1). The case where the obtained volume resistance value was 90 mΩ · cm or less was evaluated as ○, and the case where the obtained volume resistance value exceeded 90 mΩ · cm was evaluated as x.
[0083]
As a result, since the volume resistivity of Example 1 was able to be suppressed to 72 mΩ · cm and 90 mΩ · cm or less, the evaluation was good.
Moreover, since Example 2 was able to suppress the volume resistivity to 85 mΩ · cm and 90 mΩ · cm or less, the evaluation is “good”.
Furthermore, since the volume resistivity of Example 3 could be suppressed to 60 mΩ · cm and 90 mΩ · cm or less, the evaluation was “good”.
[0084]
On the other hand, since the volume resistivity of Comparative Example 1 exceeds 330 mΩ · cm and 90 mΩ · cm, the evaluation is x.
Moreover, since the volume resistivity of Comparative Example 2 exceeds 98 mΩ · cm and 90 mΩ · cm, the evaluation is x.
[0085]
The fluidity of the mixture needs to be 30 or more, preferably 40 or more in terms of spiral flow ratio, considering moldability and the like.
In Examples 1 to 3 and Comparative Examples 1 and 2, the fluidity of the mixture was 40 or more in terms of spiral flow ratio, and thus injection molding was possible as an example.
[0086]
Next, a second embodiment will be described.
In 1st Embodiment, 10-34 wt% of polyphenylene sulfide, 60-80 wt% of graphite, 1-10 wt% of ketjen black, and 5-15 wt% of chopped carbon fibers are used for the first and second separators 20, 30. Although the example of inclusion was described, the first and second separators 20 and 30 may contain 10 to 34 wt% of polyphenylene sulfide, 65 to 80 wt% of graphite, and 1 to 10 wt% of ketjen black. is there.
[0087]
By including 10 to 34 wt% of polyphenylene sulfide in the first and second separators 20 and 30, the moldability when the first and second separators 20 and 30 are injection-molded can be improved and the sealing property is excellent. Further, the first and second separators 20 and 30 can be obtained.
Thereby, the productivity and accuracy of the first and second separators 20 and 30 can be further enhanced.
[0088]
In addition, since polyphenylene sulfide is a resin having excellent heat resistance, the heat resistance of the first and second separators 20 and 30 can be increased by including the polyphenylene sulfide in the first and second separators 20 and 30. For this reason, it can be applied to a fuel cell used in a relatively high temperature region, and the use can be expanded.
Here, the reason why the content of polyphenylene sulfide is set to 10 to 34 wt% is the same as in the first embodiment.
[0089]
Moreover, electroconductivity can be improved by making a separator contain 65-80 wt% of graphite.
The reason for setting the graphite content to 65 to 80 wt% is the same as in the first embodiment.
That is, when the graphite content is less than 65 wt%, the graphite content is too small, and it becomes difficult to increase the conductivity of the first and second separators 20 and 30.
[0090]
On the other hand, if the graphite content exceeds 80 wt%, it is difficult to uniformly disperse graphite because the graphite content is too high, and extrusion molding and press molding become difficult.
Therefore, the content of the thermoplastic resin is set to 65 to 80 wt% to ensure the conductivity of the first and second separators 20 and 30 and to ensure the moldability.
[0091]
Further, by ensuring that the graphite content is 65 wt% or more, the volume resistivity (mΩ · cm) of the first and second separators 20 and 30 is reduced, and the conductivity of the first and second separators 20 and 30 is reduced. The sex can be enhanced sufficiently.
[0092]
Furthermore, electroconductivity can be further improved by including 1-10 wt% of ketjen black in a separator.
The reason for setting the ketjen black content to 1 to 10 wt% is the same as in the first embodiment.
According to the first and second separators 20 and 30 of the second embodiment, the same effects as those of the first embodiment can be obtained.
[0093]
Note that the first and second separators 20 and 40 of the above embodiment can be continuously formed by extrusion molding or press molding, and further a manufacturing method such as a hot press method, an injection molding method, a transfer molding method, or the like. It is possible to mold with.
The transfer molding method is a method in which a molding material is put into a pot part separate from the cavity for one shot, and the molten material is transferred to the cavity by a plunger and molded.
[0094]
In the embodiment, the example in which the viscosity of the polyphenylene sulfide contained in the first and second separators 20 and 30 is set to 20 to 80P has been described. However, when the viscosity of the polyphenylene sulfide is higher than 80P, the plasticity is increased. It is also possible to use an agent.
[0095]
Furthermore, in the above-described embodiment, an example in which graphite having a particle diameter of 100 μm is used has been described. However, the particle diameter of graphite is not limited to 100 μm, and other particle diameters may be used.
[0096]
In addition, in the said embodiment, although the example using "EC600JD" made by Ketjen Black International Co., Ltd. (sales agency; Mitsubishi Chemical Corporation) was explained as an example, Ketjen Black is not limited to this. For example, “EC” manufactured by Ketjen Black International Co., Ltd. can be used, and other Ketjen Black can be used.
Furthermore, as long as carbon black is excellent in conductivity like ketjen black, it can be used instead of ketjen black.
[0097]
Moreover, although the example using PAN type | system | group chopped carbon fiber was demonstrated in the said embodiment, it is not restricted to this, For example, it is also possible to use pitch type | system | group chopped carbon fiber.
[0098]
【The invention's effect】
The present invention exhibits the following effects by the above configuration.
In the first aspect of the present invention, the viscosity of the material for the fuel cell separator in the melt mass flow rate test method is 20 to 80. P A mixture containing 10 to 34 wt% of polyphenylene sulfide, 65 to 80 wt% of graphite, and 1 to 10 wt% of ketjen black was used, and the fluidity of this mixture was set to a value exceeding 30 in the spiral flow ratio. Therefore, the moldability when the separator is injection-molded can be improved. Thereby, the productivity and accuracy of the separator can be further increased.
[0099]
In addition, since polyphenylene sulfide is a resin excellent in heat resistance, the heat resistance of the separator can be increased by including polyphenylene sulfide in the separator. For this reason, it can be applied to a fuel cell used in a relatively high temperature region, and the use can be expanded.
Therefore, the content of polyphenylene sulfide was set to 10 to 34 wt% to ensure the moldability, sealing properties, heat resistance and bonding properties of the separator and to ensure sufficient conductivity.
[0100]
In addition, the graphite content was set to 65 to 80 wt% to ensure the conductivity of the separator and to ensure the moldability.
Furthermore, by ensuring the graphite content at 65 wt% or more, the volume resistivity of the separator can be reduced, and the conductivity of the separator can be sufficiently increased.
In addition, the conductivity can be further increased by including 1 to 10 wt% of ketjen black in the separator.
[0101]
According to a second aspect of the present invention, the viscosity of the material for the fuel cell separator in the melt mass flow rate test method is 20 to 80. P A mixture of 10 to 34 wt% polyphenylene sulfide, 60 to 80 wt% graphite, 1 to 10 wt% ketjen black, and 5 to 15 wt% chopped carbon fiber. By forming the ratio at a value exceeding 30, the moldability of the fuel cell separator can be further enhanced. In addition, the strength and heat resistance of the separator can be increased.
[0102]
[Brief description of the drawings]
FIG. 1 relates to the present invention. Manufactured with a method for manufacturing a fuel cell separator Fuel cell separator Burn Battery Example used for FIG.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
3 is a cross-sectional view taken along line BB in FIG.
FIG. 4 is a cross-sectional view showing a fuel cell separator according to the present invention.
FIG. 5 is a diagram explaining how to obtain volume resistivity.
FIG. 6 is a graph showing the relationship between the graphite content and the volume resistivity.
FIG. 7 is a graph showing the relationship between the ketjen black content and the volume resistivity.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 12 ... Electrolyte membrane, 13 ... Anode side electrode, 14 ... Cathode side electrode, 15 ... Anode side electrode diffusion layer (diffusion layer), 16 ... Cathode side electrode diffusion layer (diffusion layer), 18 ... Separator ( Fuel cell separator), 20... First separator, 30.

Claims (2)

In the method of manufacturing a fuel cell separator in which the anode side electrode and the cathode side electrode along the electrolyte membrane are sandwiched from both sides through the diffusion layer,
A mixture containing 10 to 34 wt% of polyphenylene sulfide having a viscosity of 20 to 80 P in a melt mass flow test method, 65 to 80 wt% of graphite, and 1 to 10 wt% of ketjen black in the material for the fuel cell separator. A method for producing a separator for a fuel cell, characterized in that the fluidity of the mixture is set to a value exceeding 30 in a spiral flow ratio. In the method of manufacturing a fuel cell separator in which the anode side electrode and the cathode side electrode along the electrolyte membrane are sandwiched from both sides through the diffusion layer,
10 to 34 wt% of polyphenylene sulfide having a viscosity of 20 to 80 P in the melt mass flow test method, 60 to 80 wt% of graphite, 1 to 10 wt% of ketjen black, and chopped carbon fiber. A method for producing a separator for a fuel cell, comprising using a mixture containing 5 to 15 wt% and setting the fluidity of the mixture to a value exceeding 30 in a spiral flow ratio.

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