JP2004111304A - Fuel cell separator and method of manufacturing the same - Google Patents

Abstract

A method for manufacturing a fuel cell separator is provided.
The present invention relates to a method for manufacturing a separator (9) comprising a plate having a power generation range (22) composed of a porous member (35) mainly composed of resin and graphite powder and a relatively dense outer peripheral part (21). Here, a first step of forming a relatively dense outer peripheral portion 21 using the molds 30 and 31 and a second step of forming other portions are provided. The second step is started without taking out the dense outer peripheral portion 21 from the molds 30, 31 (lower mold 30) used in the above.
[Selection diagram] FIG.

Description

【００２１】
気孔率は水銀圧入法で、気体透過性はＪＩＳＫ７１２６（差圧法）で、また、機会的特性に関してはＪＩＳＫ６９１１に準拠した。
【００２２】
次に、このような構成のセパレータ９の製造方法を図３、図４を用いて説明する。
【００２３】
セパレータ９を、下金型３０と上金型３１を用いて形成する。後述するように、下金型３０と上金型３１のセパレータ形成部に対峙する面、つまり下金型３０の上側の表面と、上金型３１の下側の表面はセパレータ９のデザインに沿った加工を施しておく。
【００２４】
下金型３０は、直方体形状の部材の上表面に、セパレータ９形状の溝であるプレート型溝部３９を形成したものである。ただし、溝の深さを成形後のセパレータ９の厚さより大きい深さＢとする。ここで、深さＢは後述するように充填した直後の緻密質部材３４の高さであり、これを圧縮して形成するので、形成されたセパレータ９の厚みは深さＢより小さくなる。
【００２５】
さらに、下金型３０の発電範囲２２に対峙する部分を上下可動の可動部３６により形成し、可動部３６を上に持ち上げた場合には、可動部３６の下側の下金型３０内部に空洞部３７が形成されるように構成する。可動部３６を持ち上げた時には、セパレータ９形状のプレート型溝部３９の中央部に位置する発電範囲２２に対峙する部分が高さ（Ｂ−Ａ）だけ突出する。このとき、可動部３６の下に形成される空洞部３７を維持するために、空洞部３７にはいくつかの支柱を設けてもよい。
【００２６】
一方、上金型３１は、プレートにセパレータ９を構成するプレートと同じ面積の突出部を構成したものである。下金型３０に構成したプレート型溝部３９に、セパレータ材料を充填して、この上金型３１を押し付けて圧縮することで、セパレータ９を成形する。
【００２７】
ここでは、外周部２１と発電範囲２２を同一の金型３０、３１を用いて成形する。以下、その工程を説明する。
【００２８】
まず、緻密質部材３４を用いて外周部２１の予備成形を行う。空洞部３７を形成するように可動部３６を持ち上げてから固定する。このとき、可動部３６はプレート型溝部３９の外周部（下金型３０の上端面３０ａ）より、Ａだけ低くなるようにセットする。つまり、プレート型溝部３９の深さをＢとしたときに、可動部３６は溝底部から高さ（Ｂ−Ａ）だけ突出するようにセットする。
【００２９】
このような状態で、可動部３６の周囲の溝部、つまり外周部２１が形成される部分に緻密質部材３４を充填する。このとき、緻密質部材３４を下金型３０の上端面３０ａに相当する部分まで充填するので、緻密質部材３４の厚みは、溝の深さＢに等しくなる。
【００３０】
ここで、図６に示すように、緻密質部材３４が充填される範囲と可動部３６が占める範囲では、緻密質部材３４の充填時には可動部３６が占める範囲の方が隙間Ａの分だけ低くなっている。これは、外周部２１の予備成形時に、上方から上金型３１を押し付け、緻密質部材３４を隙間Ａの分だけ圧縮して外周部２１を予備成形するためである。この隙間Ａが大きいと、緻密質部材３４が充填した時に可動部３６の上面に流れ出てしまう可能性が生じるので、ここでは、隙間Ａの高さを０．５〜１０ｍｍ、好ましくは０．５〜５ｍｍとする。これにより、緻密質部材３４が充填範囲以外に拡散するのを防ぐことができる。
【００３１】
このように緻密質部材３４を充填したら、短時間の熱圧縮により外周部２１の予備成形を行う。このとき、図５に示すように、外周部２１に重なる形状のプレート８を下金型３０と上金型３１との間に配置することにより、緻密質部材３４の圧縮を増大し、緻密性を増大することもできる。
【００３２】
緻密質部材３４の予備成形後には、緻密質部材３４に用いる樹脂が半硬化状態になっていることが好ましく、それゆえ、用いる樹脂も速硬化性であっては調整が難しくなる。このときは、少なくとも外周部２１の形状保持がなされ、後述する発電範囲２２の成形時に、緻密質部材３４を構成する樹脂が溶融して流れ込まない程度に硬化していればよい。
【００３３】
次に、多孔質部材３５により発電範囲２２の成形を行う。外周部２１の予備成形後、上述するように緻密質部材３４を構成する樹脂が完全に硬化する前に多孔質部材３５を充填する。ここでは、緻密質部材３４を構成する樹脂の硬化度が９５％以下の状態で、多孔質部材３５を充填する。ここで、緻密質部材３４の樹脂硬化度は、硬化がほぼ終了した状態に対する電気伝導度、機械的強度、ＤＳＣ等の熱分析等により相対的に検出し、緻密質部材３４が設定した硬化度になったら多孔質部材３５を充填する。
【００３４】
多孔質部材３５を充填する際には、可動部３６を下方向に移動させ、セパレータ９形状のプレート型溝部３９の底面全体が等しい高さとなるようにする。この状態で多孔質部材３５を充填し、上金型３１を用いて熱圧縮する。ここでは、例えば、緻密質部材３４の予備成形の際と同じ温度で三分間成形する。
【００３５】
ここで、多孔質部材３５と緻密質部材３４との熱膨張率に差がある場合には、上記のような熱圧縮の工程の際に、境界部で亀裂等が生じる恐れがある。これを防止するために、多孔質部材３５は、緻密質部材３４と同種の樹脂を用いる。
【００３６】
このように、外周部２１の緻密質部材３４を構成する樹脂の硬化が完全に終了する前に、発電範囲２２の多孔質部材３５を充填して成形することで、過度の圧力をかけずに外周部２１と発電範囲２２を一体に構成することができる。
【００３７】
なお、成形の第一段階で、緻密質部材３４の予備成形時には、下金型３０のうち発電範囲２２に対峙する部分は、緻密質部材３４が発電範囲２２に充填されないような構造であればよい。つまり、ここでは可動部３６を上下可動としたが、この他にも、緻密質部材３４の成形時にはプレート型溝部３９内に発電範囲２２のサイズのプレートを設置することもできる。ただしこの場合には、多孔質部材３５の充填時には、このプレートを取り除く必要がある。
【００３８】
次に、このように製造したセパレータ９の性能を説明する。
【００３９】
プレート９の緻密質部材３４と多孔質部材３５の境界を確認するために、境界部を含むセパレータ９の任意の３箇所をカットすると、図７に示す緻密質部材３４と多孔質部材３５の部材混在範囲４０はいずれも１ｍｍ以下となった。ここで、部材混在範囲４０では、水素ガスや空気に供給する水分を多孔質部材３５のようには含有できないため、発電の範囲として使用することができない。また、緻密質部材３４よりも機械的強度が小さく、ガスケット設置溝１５を形成する領域としても使用することができない。しかしながら、異なる部材を用いて一体の物質を作る際には、境界部の機械的強度を維持するために、この部材混在範囲４０を形成する方が好ましい。そのため、部材混在範囲４０を備えるとともにその領域を抑えることで、境界部の機械的強度を維持しつつ、発電等に使用できない領域を抑えることができる。
【００４０】
また、セパレータ９の端部のガス遮蔽性を確認した結果を表２に示す。ここでは、本実施形態で生成したセパレータ９を組み立てて単セルを組み、水中に埋没してアノード側およびカソード側のガス流路１３に窒素ガスを流す。さらに、水素ガスマニホールド１０および空気マニホールド１１の出口側に栓をして、一定の圧力をセル内にかける。ここで、条件１は絶対圧力で１５０ｋＰａをかけた場合、条件２は絶対圧力で２００ｋＰａをかけた場合とする。このような条件下でセパレータ９の端部からのガスリーク状態を観察する。ここで、比較例として、多孔質材のみで形成したセパレータを用いた単セルについても同条件で観察を行い、本実施形態と比較例のガスリークの結果を表２に示す。
【００４１】
【表２】

【００４２】
表２に示すように、比較例では条件１、条件２においてもガスリークを生じたのに対して、本実施形態に従って製造したセパレータ９を用いた単セルは、条件１でも、条件２でもガスリークを生じないことを確認できる。
【００４３】
つまり、本実施形態のようにセパレータ９を成形することで、セパレータ９に必要な性質を維持しつつ、製造工程を簡単にすることができる。
【００４４】
次に、本実施形態における効果を説明する。
【００４５】
樹脂および黒鉛粉末を主成分とする多孔質の部分（発電範囲２２）と、相対的に緻密質の部分（外周部２１）と、を有するプレートにより構成される燃料電池セパレータを次のように製造する。下金型３０を用いて外周部２１を成形する第一の工程と、それ以外の部分を形成する第二の工程と、を有し、第一の工程において使用した下金型３０から、外周部２１を取り出すことなく、第二の工程を開始する。このように、同一の下金型３０内で複数段に分けて成形することで、工程数を低減することができ、効率良く製造することが可能である。
【００４６】
また、外周部２１を少なくとも樹脂を用いて構成し、外周部２１を構成している樹脂が完全に硬化する前に、発電範囲２２を形成することで、発電範囲２２に過度の負荷をかけることなく外周部２１と発電範囲２２間の接合を十分に行うことができる。これにより、機械的強度の小さな部材、例えば多孔質部材３５を用いても容易に製造することができる。
【００４７】
ここでは、外周部２１を構成する緻密質部材３４の樹脂の硬化度が９５％以下の状態で、発電範囲２２を構成する多孔質部材３５の充填を開始する。これにより、過度の負荷をかけずに外周部２１と発電範囲２２とを一体化することができる。また、部材混合範囲４０を形成することができ、境界部の強度を維持することができる。９５％より硬化してしまうと、境界部分の接合がうまくいかない場合があり、多孔質部材３５の成形が、硬化した緻密質部材３４の形状精度に依存することがある。
【００４８】
さらに、外周部２１を成形する際には、発電範囲２２が形成される領域に下金型３０の一部（可動部３６）を配置し、発電範囲２２を成形する際には、発電範囲２２が形成される領域から下金型３０の一部（可動部３６）を取り除く。これにより、外周部２１を成形後に下金型３０から取り出すことなく発電範囲２２を形成できる。これにより、工程を簡単にすることができ、効率良くセパレータ９を製造することができる。
【００４９】
下金型３０の発電範囲２２を圧縮成形するための溝部の深さ（下金型３０の上端面３０ａと可動部３６の上面との高さの差）を、外周部２１を成形する際には、プレート型溝部３９の外周部２１を形成する部分の深さＢと比較して浅く、ここでは深さＡに設定し、発電範囲２２を成形する際には、深さＢと等しくなるように設定する。このように溝の深さを変えることで、金型３０、３１で外周部２１および発電部２２の両方を成形することができる。
【００５０】
また、発電範囲２２を形成するための前記金型の一部（可動部３６）の上面を、外周部２１を成形する際には、外周部２１の成形後の上端面と略同じ高さとし、発電範囲２２を成形する際には、外周部２１の下端面と同じ高さとなるようにする。つまり、ここでは下金型３０の一部を可動部３６のように上下するようにしたため、外周部２１を圧縮成形により適切に形成した下金型３０を用いて簡単に、且つ、適切に発電範囲２２の圧縮成形することができる。
【００５１】
樹脂および黒鉛粉末を主成分とする多孔質部材３５により構成した発電範囲２２と、相対的に緻密質な緻密質部材３４を用いて構成した外周部２１を有するプレートによりセパレータ９を構成する。このようなセパレータ９を、外周部２１を成形する下金型３０から外周部２１を取り出さずに、発電範囲２２を成形する。これにより、セパレータ９の製造工程を簡単にすることができ、製造コストを低減することができる。また、セパレータ９によるガスの遮蔽性を保持することができる。
【００５２】
ここでは多孔質部材３５により構成された発電範囲２２を気孔率が５〜６０％であるように構成する。多孔質部材３５により構成される部分を気孔率５〜６０％に構成する事で、機械的強度、成形性を維持することができる。
【００５３】
さらに、多孔質部材３５の組成を樹脂１００重量部に対して炭素粉末２３５〜２２２２重量部を主組成とし、緻密質部材３４の組成を樹脂１００重量部に対して炭素粉末０〜２２２２重量部を主成分とすることにより、セパレータ９として要求される機械的・電気的特性を満足することができる。また、外周部２１を緻密質部材３４で構成する場合、緻密質部材３４の気孔率を５％以下にすることで、スタック外部へのガスリークを抑えることができる。
【００５４】
このように、通常、求められる性質を備えたセパレータ９を、本実施形態により製造することができる。
【００５５】
緻密質部材３４に繊維基材を含ませることにより、セパレータ９自身の機械的強度を飛躍的に向上させることができる。特に、セパレータ９外周部に繊維基材を有した緻密質材を用いることで、ガスシール性を確保しつつプレートの強度も確保することができる。
【００５６】
なお、本発明は、上記実施の形態に限定されるわけではなく、特許請求の範囲に記載の技術思想の範囲内で様々な変更が成し得ることは言うまでもない。
【図面の簡単な説明】
【図１】本実施形態に用いるセパレータの概略図である。
【図２】本実施形態に用いるセパレータの構成部材の説明図である。
【図３】本実施形態に用いる下金型の概略および外周部成形時の説明図である。
【図４】本実施形態における発電範囲成形時の説明図である。
【図５】本実施形態で説明するセパレータの製造方法の一例を示す図である。
【図６】本実施形態の外周部成形時の状態の説明図である。
【図７】本実施形態のセパレータの緻密質部材と多孔質部材の境界部の状態図である。
【符号の説明】
９　　セパレータ
２１　外周部（緻密質な部分）
２２　発電範囲（多孔質な部分）
３０　下金型（金型）
３１　上金型
３４　緻密質部材
３５　多孔質部材
３６　可動部（金型の一部）[0001]
[Industrial applications]
The present invention relates to a fuel cell separator and a method for manufacturing the same, and more particularly, to a separator for a polymer electrolyte fuel cell and a method for manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a polymer electrolyte fuel cell has been known as a power generation device using an electromotive force generated by an electrochemical reaction between hydrogen and oxygen. This is achieved by stacking a plurality of unit cells each having a fuel cell separator having a fluid passage for supplying a fuel gas such as hydrogen and a fuel cell separator having a fluid passage for supplying an oxidizing gas such as air. It is constituted by. Generally, these fuel cell separators have, on the outer peripheral side of a range where a fluid passage is formed, a through hole through which a tightening bolt is passed, and a manifold for feeding various gases into a fluid passage formed on the surface of the fuel cell separator. Further, a gasket or the like for fixing between the lamination surfaces is provided.
[0003]
The fuel cell stack is configured by stacking a plurality of fuel cell separators and compressing them with a constant load. Therefore, when the fastening bolt holes and the respective manifolds are arranged close to each other on the outer peripheral portion of the fuel cell separator, a portion easily damaged in the fuel cell separator occurs. In particular, the fuel cell separator containing graphite powder and resin as main components has a remarkable phenomenon when compared with that made of metal.
[0004]
For this reason, Japanese Patent Application Laid-Open No. 2002-63913 discloses a manufacturing method in which a power generation part and a fiber-reinforced fuel cell separator outer frame part are separately preformed, and the respective preformed bodies are integrated by hot pressing. Have been. For example, a preformed body for a gas channel member formed from a mixture of a carbon powder and a thermosetting resin, and a frame formed from a mixture of a carbon material and a thermosetting resin obtained by mixing carbon fibers and carbon powder. The preform for the member and the preform are placed in a mold and are integrally hot-pressed.
[0005]
[Problems to be solved by the invention]
However, it is difficult to apply the above-described construction method in which the preformed bodies of the power generation portion and the outer frame portion of the fuel cell separator are formed and then formed again to integrate them, with a member having low mechanical strength. Further, the number of steps is large, so that it is not suitable for providing an inexpensive separator.
[0006]
Thus, the present invention provides an efficient method of manufacturing a fuel cell separator and a fuel cell separator manufactured by the method.
[0007]
[Means for solving the problem]
The present invention relates to a method for manufacturing a fuel cell separator including a plate having a porous portion mainly composed of a resin and graphite powder and a relatively dense portion. Here, a first step of molding the relatively dense portion using a mold, and a second step of forming the other portion, and used in the first step The second step is started without removing the dense portion from the mold.
[0008]
Further, in the fuel cell separator, the porous portion is formed without removing the dense portion from a mold for forming the dense portion.
[0009]
[Action and effect]
By starting the second step without removing the dense part from the mold used in the first step, it is possible to mold with the same mold and to efficiently manufacture the fuel cell separator. Can be.
[0010]
In addition, by forming the porous portion without removing the dense portion from the mold for forming the dense portion, the number of steps can be reduced, and an inexpensive fuel cell separator can be provided. .
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
FIGS. 1 and 2 schematically show a fuel cell separator (hereinafter, separator) used in the present embodiment. Here, the configuration of the separator 9 used on the anode side of a polymer electrolyte fuel cell stack using hydrogen gas as fuel gas and air as oxidant gas will be described.
[0012]
The separator 9 is constituted by a power generation range 22 having a gas flow path 13 formed on the surface and an outer peripheral portion 21. The gas flow path 13 is formed in the entire power generation range 22 as shown in FIG. 1, and an end of the gas flow path 13 communicates with the hydrogen gas manifold 10 which is an internal manifold formed in the outer peripheral portion 21. The hydrogen gas manifold 10 distributes hydrogen gas to the anode electrode or collects gas after power generation from the anode electrode during power generation in a fuel cell stack configured by stacking single cells using the separator 9, and extends in the stacking direction. This is a flow path for hydrogen gas. In addition, an air manifold 11 for distributing or collecting air in the stacking direction when generating power is formed on the outer peripheral portion 21.
[0013]
Further, the outer peripheral portion 21 is a cooling passage, which is a flow passage extending in the stacking direction, for supplying cooling water for removing heat accompanying power generation to each single cell or collecting cooling water after cooling from the single cell. The water manifold 12 is constituted. Further, a through hole 14 of a tie rod used for fastening the fuel cell stack in the stacking direction is formed in the outer peripheral portion 21. A gasket installation groove 15 is formed on the outer periphery of the power generation range 22 of the outer peripheral portion 21.
[0014]
Here, the separator 9 in which the gas flow path 13 of the hydrogen gas is formed in the power generation range 22 is shown, but the separator 9 which forms the gas flow path 13 of the air may have the same configuration. However, the end of the gas passage 13 is connected to the air manifold 11, and the shape of the gas passage 13 is symmetric in FIG.
[0015]
In the present embodiment, the outer peripheral portion 21 of the separator 9 is constituted by the dense member 34, and the power generation range 22 is constituted by the porous member 35.
[0016]
The power generation range 22 is formed using the porous member 35 so that the porosity after molding is 5 to 70%. Here, as the porous member 35, one having a main composition of 235 to 2222 parts by weight of carbon powder with respect to 100 parts by weight of the resin is used. Here, the power generation range 22 is configured to have, for example, an average pore diameter of 0.8 to 1.5 μm and a porosity of 26.5%.
[0017]
On the other hand, the outer peripheral portion 21 is a dense resin-graphite composite material (dense member 34) having a porosity of 5% or less, here less than 2%, having a main composition of 0 to 2222 parts by weight of carbon powder with respect to 100 parts by weight of resin. It consists of. In addition, by including the fiber base material in the dense member 34, the mechanical strength of the outer peripheral portion 21 is improved.
[0018]
By using the porous member 35 as a part of the separator 9, it is possible to make the pores of the porous member 35 contain hydrogen gas, moisture for air humidification, or part of water generated by the power generation reaction. This makes it possible to humidify the hydrogen gas and the air to efficiently generate power. Further, when the pressure of the hydrogen gas or air flowing through the fuel gas flow path 13 is increased, the hydrogen gas or air can be preferentially contained in the porous portion. Can be effectively suppressed from leaking out of the separator 9.
[0019]
Table 1 is an example of an outline of the physical properties of the materials constituting the power generation range 22 and the outer peripheral portion 21 used in the present embodiment. Here, Table 1 shows the characteristics in the case where the power generation range 22 and the outer peripheral portion 21 are formed of the same resin, and each is formed separately.
[0020]
[Table 1]

[0021]
The porosity was in accordance with the mercury intrusion method, the gas permeability was in accordance with JIS K7126 (differential pressure method), and the opportunity characteristics were in accordance with JIS K6911.
[0022]
Next, a method of manufacturing the separator 9 having such a configuration will be described with reference to FIGS.
[0023]
The separator 9 is formed using the lower mold 30 and the upper mold 31. As will be described later, the surfaces of the lower mold 30 and the upper mold 31 facing the separator forming portion, that is, the upper surface of the lower mold 30 and the lower surface of the upper mold 31 conform to the design of the separator 9. Have been processed.
[0024]
The lower mold 30 is formed by forming a plate-shaped groove 39 which is a groove in the shape of the separator 9 on the upper surface of a rectangular parallelepiped member. However, the depth of the groove is set to a depth B larger than the thickness of the separator 9 after molding. Here, the depth B is the height of the dense member 34 immediately after filling, as described later, and is formed by compressing the dense member 34. Therefore, the thickness of the formed separator 9 is smaller than the depth B.
[0025]
Further, a portion of the lower mold 30 facing the power generation range 22 is formed by a movable portion 36 that is movable up and down, and when the movable portion 36 is lifted up, the lower mold 30 is placed inside the lower mold 30 below the movable portion 36. The cavity 37 is formed. When the movable portion 36 is lifted, a portion facing the power generation range 22 located at the center of the plate-shaped groove portion 39 having the shape of the separator 9 protrudes by a height (BA). At this time, in order to maintain the hollow portion 37 formed below the movable portion 36, the hollow portion 37 may be provided with some columns.
[0026]
On the other hand, the upper mold 31 is configured such that the plate has a protrusion having the same area as the plate constituting the separator 9. The separator 9 is formed by filling a plate material groove portion 39 formed in the lower mold 30 with a separator material and pressing and compressing the upper mold 31.
[0027]
Here, the outer peripheral portion 21 and the power generation range 22 are formed using the same molds 30 and 31. Hereinafter, the process will be described.
[0028]
First, the outer peripheral portion 21 is preformed using the dense member 34. The movable portion 36 is lifted and fixed so as to form the cavity 37. At this time, the movable portion 36 is set so as to be lower by A than the outer peripheral portion of the plate-shaped groove portion 39 (the upper end surface 30a of the lower mold 30). That is, when the depth of the plate-shaped groove portion 39 is B, the movable portion 36 is set so as to protrude from the groove bottom portion by the height (BA).
[0029]
In such a state, the dense member 34 is filled in the groove around the movable portion 36, that is, the portion where the outer peripheral portion 21 is formed. At this time, since the dense member 34 is filled up to the portion corresponding to the upper end surface 30a of the lower mold 30, the thickness of the dense member 34 becomes equal to the depth B of the groove.
[0030]
Here, as shown in FIG. 6, when the dense member 34 is filled and the movable portion 36 occupies, the range occupied by the movable portion 36 when the dense member 34 is filled is lower by the gap A. Has become. This is because the upper mold 31 is pressed from above during the preforming of the outer peripheral portion 21 and the dense member 34 is compressed by the gap A to preform the outer peripheral portion 21. If the gap A is large, there is a possibility that when the dense member 34 is filled, the gap A may flow out to the upper surface of the movable portion 36. Therefore, the height of the gap A is set to 0.5 to 10 mm, preferably 0.5 to 10 mm. ５5 mm. Thereby, it is possible to prevent the dense member 34 from diffusing outside the filling range.
[0031]
After filling the dense member 34 in this way, the outer peripheral portion 21 is preformed by a short-time thermal compression. At this time, by arranging the plate 8 having a shape overlapping the outer peripheral portion 21 between the lower mold 30 and the upper mold 31, as shown in FIG. 5, the compression of the dense member 34 is increased, and Can also be increased.
[0032]
After the preliminary molding of the dense member 34, it is preferable that the resin used for the dense member 34 be in a semi-cured state. At this time, at least the shape of the outer peripheral portion 21 is maintained, and it is sufficient that the resin constituting the dense member 34 is melted and hardened so as not to flow therein when forming the power generation range 22 described later.
[0033]
Next, the power generation range 22 is formed by the porous member 35. After the outer peripheral portion 21 is preformed, the porous member 35 is filled before the resin constituting the dense member 34 is completely cured as described above. Here, the porous member 35 is filled in a state where the degree of cure of the resin constituting the dense member 34 is 95% or less. Here, the degree of hardening of the resin of the dense member 34 is relatively detected by electrical analysis, mechanical strength, thermal analysis such as DSC with respect to the state where the hardening is almost completed, and the hardening degree set by the dense member 34 is set. Then, the porous member 35 is filled.
[0034]
When filling the porous member 35, the movable portion 36 is moved downward so that the entire bottom surface of the plate-shaped groove portion 39 having the shape of the separator 9 has the same height. In this state, the porous member 35 is filled and thermally compressed using the upper mold 31. Here, for example, molding is performed for 3 minutes at the same temperature as in the preliminary molding of the dense member 34.
[0035]
Here, if there is a difference in the coefficient of thermal expansion between the porous member 35 and the dense member 34, a crack or the like may be generated at the boundary during the above-described thermal compression process. To prevent this, the porous member 35 uses the same resin as the dense member 34.
[0036]
As described above, before the curing of the resin constituting the dense member 34 of the outer peripheral portion 21 is completely completed, the porous member 35 of the power generation range 22 is filled and molded, so that excessive pressure is not applied. The outer peripheral portion 21 and the power generation range 22 can be integrally formed.
[0037]
In the first stage of molding, when the dense member 34 is preformed, a portion of the lower mold 30 facing the power generation range 22 has a structure in which the dense member 34 is not filled in the power generation range 22. Good. That is, although the movable portion 36 is movable up and down here, a plate having the size of the power generation range 22 may be provided in the plate-shaped groove portion 39 when the dense member 34 is formed. However, in this case, when filling the porous member 35, it is necessary to remove this plate.
[0038]
Next, the performance of the separator 9 thus manufactured will be described.
[0039]
In order to confirm the boundary between the dense member 34 and the porous member 35 of the plate 9, any three places of the separator 9 including the boundary are cut, and the members of the dense member 34 and the porous member 35 shown in FIG. Each of the mixed ranges 40 was 1 mm or less. Here, in the member mixed range 40, the water to be supplied to the hydrogen gas or the air cannot be contained as in the case of the porous member 35, and thus cannot be used as a power generation range. Further, the mechanical strength of the dense member 34 is smaller than that of the dense member 34, and the dense member 34 cannot be used as a region where the gasket installation groove 15 is formed. However, when an integrated material is formed using different members, it is preferable to form the member mixed range 40 in order to maintain the mechanical strength of the boundary. Therefore, by providing the member mixture range 40 and suppressing the region, it is possible to suppress the region that cannot be used for power generation or the like while maintaining the mechanical strength of the boundary portion.
[0040]
In addition, Table 2 shows the result of confirming the gas shielding property at the end of the separator 9. Here, a single cell is assembled by assembling the separator 9 generated in the present embodiment, and immersed in water to flow a nitrogen gas through the gas passages 13 on the anode side and the cathode side. Further, the outlets of the hydrogen gas manifold 10 and the air manifold 11 are plugged to apply a certain pressure to the inside of the cell. Here, condition 1 is a case where 150 kPa is applied in absolute pressure, and condition 2 is a case where 200 kPa is applied in absolute pressure. Under such conditions, the state of gas leak from the end of the separator 9 is observed. Here, as a comparative example, a single cell using a separator formed only of a porous material was observed under the same conditions, and the results of gas leaks of the present embodiment and the comparative example are shown in Table 2.
[0041]
[Table 2]

[0042]
As shown in Table 2, in the comparative example, a gas leak occurred under the conditions 1 and 2, whereas the single cell using the separator 9 manufactured according to the present embodiment produced a gas leak under the conditions 1 and 2. It can be confirmed that it does not occur.
[0043]
That is, by forming the separator 9 as in the present embodiment, the manufacturing process can be simplified while maintaining the properties required for the separator 9.
[0044]
Next, effects of the present embodiment will be described.
[0045]
A fuel cell separator composed of a plate having a porous portion mainly composed of resin and graphite powder (power generation range 22) and a relatively dense portion (outer peripheral portion 21) is manufactured as follows. I do. The method includes a first step of forming the outer peripheral portion 21 using the lower mold 30 and a second step of forming other portions, and the outer periphery 21 is formed from the lower mold 30 used in the first step. The second step is started without removing the part 21. As described above, by forming a plurality of stages in the same lower mold 30, the number of steps can be reduced, and efficient production can be achieved.
[0046]
Further, by forming the outer peripheral portion 21 using at least a resin and forming the power generation range 22 before the resin forming the outer peripheral portion 21 is completely cured, an excessive load is applied to the power generation range 22. Therefore, the joining between the outer peripheral portion 21 and the power generation range 22 can be sufficiently performed. Thereby, it can be easily manufactured even if a member having a small mechanical strength, for example, a porous member 35 is used.
[0047]
Here, the filling of the porous member 35 forming the power generation range 22 is started in a state where the degree of cure of the resin of the dense member 34 forming the outer peripheral portion 21 is 95% or less. Accordingly, the outer peripheral portion 21 and the power generation range 22 can be integrated without applying an excessive load. In addition, the member mixing range 40 can be formed, and the strength of the boundary can be maintained. If it is hardened by more than 95%, the bonding at the boundary may not be successful, and the forming of the porous member 35 may depend on the shape accuracy of the hardened dense member 34.
[0048]
Further, when molding the outer peripheral portion 21, a part (the movable portion 36) of the lower mold 30 is arranged in a region where the power generation range 22 is formed. A part of the lower mold 30 (movable part 36) is removed from the region where is formed. Thus, the power generation range 22 can be formed without removing the outer peripheral portion 21 from the lower mold 30 after molding. Thereby, the process can be simplified, and the separator 9 can be manufactured efficiently.
[0049]
The depth of the groove (the difference between the height of the upper end surface 30a of the lower mold 30 and the upper surface of the movable portion 36) for compression molding the power generation range 22 of the lower mold 30 is determined when the outer peripheral portion 21 is molded. Is shallower than the depth B of the portion forming the outer peripheral portion 21 of the plate-shaped groove portion 39, and is set to the depth A here, and is set to be equal to the depth B when the power generation range 22 is formed. Set to. By changing the depth of the groove in this manner, both the outer peripheral portion 21 and the power generation portion 22 can be formed by the molds 30 and 31.
[0050]
When forming the outer peripheral portion 21, the upper surface of a part of the mold (the movable portion 36) for forming the power generation range 22 is set to be substantially the same height as the upper end surface of the outer peripheral portion 21 after molding, When forming the power generation range 22, the height is set to be the same as the lower end surface of the outer peripheral portion 21. In other words, in this case, since a part of the lower mold 30 is moved up and down like the movable portion 36, the outer peripheral portion 21 can be easily and appropriately generated by using the lower mold 30 appropriately formed by compression molding. Range 22 compression molding can be performed.
[0051]
The separator 9 is constituted by a power generation range 22 constituted by a porous member 35 mainly composed of resin and graphite powder, and a plate having an outer peripheral portion 21 constituted by a relatively dense dense member 34. The power generation range 22 of the separator 9 is formed without removing the outer peripheral portion 21 from the lower mold 30 that forms the outer peripheral portion 21. Thereby, the manufacturing process of the separator 9 can be simplified, and the manufacturing cost can be reduced. Further, the gas shielding properties of the separator 9 can be maintained.
[0052]
Here, the power generation range 22 constituted by the porous member 35 is configured such that the porosity is 5 to 60%. By configuring the portion constituted by the porous member 35 to have a porosity of 5 to 60%, mechanical strength and moldability can be maintained.
[0053]
Further, the composition of the porous member 35 is mainly composed of 235 to 2222 parts by weight of carbon powder with respect to 100 parts by weight of the resin, and the composition of the dense member 34 is composed of 0 to 2222 parts by weight of carbon powder with respect to 100 parts by weight of the resin. By using it as a main component, mechanical and electrical characteristics required for the separator 9 can be satisfied. In the case where the outer peripheral portion 21 is formed of the dense member 34, gas leak to the outside of the stack can be suppressed by setting the porosity of the dense member 34 to 5% or less.
[0054]
As described above, usually, the separator 9 having the required properties can be manufactured according to the present embodiment.
[0055]
By including the fiber base material in the dense member 34, the mechanical strength of the separator 9 itself can be significantly improved. In particular, by using a dense material having a fibrous base material on the outer peripheral portion of the separator 9, the strength of the plate can be secured while securing gas sealing properties.
[0056]
It is needless to say that the present invention is not limited to the above embodiment, and various changes can be made within the scope of the technical idea described in the claims.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a separator used in the present embodiment.
FIG. 2 is an explanatory diagram of constituent members of a separator used in the present embodiment.
FIG. 3 is a schematic diagram of a lower mold used in the present embodiment and an explanatory diagram during molding of an outer peripheral portion.
FIG. 4 is an explanatory diagram at the time of forming a power generation range in the present embodiment.
FIG. 5 is a diagram illustrating an example of a method for manufacturing a separator described in the present embodiment.
FIG. 6 is an explanatory diagram of a state at the time of molding the outer peripheral portion of the embodiment.
FIG. 7 is a state diagram of a boundary between a dense member and a porous member of the separator of the present embodiment.
[Explanation of symbols]
9 Separator 21 outer periphery (dense part)
22 Power generation range (porous part)
30 Lower mold (mold)
31 Upper mold 34 Dense member 35 Porous member 36 Movable part (part of mold)

Claims (10)

In a method for producing a fuel cell separator composed of a plate having a porous portion having a resin and graphite powder as main components and a relatively dense portion,
A first step of molding the relatively dense portion using a mold,
A second step of forming the other part,
A method for producing a fuel cell separator, wherein the second step is started without removing the dense portion from the mold used in the first step. The dense portion is configured using at least a resin,
The method for producing a fuel cell separator according to claim 1, wherein the porous portion is formed before the resin constituting the dense portion is completely cured. The method for manufacturing a fuel cell separator according to claim 2, wherein the porous portion is formed in a state where the degree of cure of the resin constituting the dense portion is 95% or less. When molding the dense portion, a part of the mold is arranged in a region where the porous portion is formed,
4. The method of manufacturing a fuel cell separator according to claim 2, wherein when molding the porous portion, a part of the mold is removed from a region where the porous portion is formed. 5. The depth of the groove for compression molding the porous portion of the mold,
When molding the dense portion, shallower than the depth of the groove for compression molding the dense portion,
5. The method for manufacturing a fuel cell separator according to claim 4, wherein when forming the porous portion, the depth is set to be equal to a depth of a groove for compression-molding the dense portion. The mold for forming the porous portion is configured to be vertically movable,
An upper end surface of a part of the mold for forming the porous portion,
When molding the dense portion, the height is substantially the same as the upper end surface after molding only the dense portion,
The method for manufacturing a fuel cell separator according to claim 4, wherein when forming the porous portion, the height is made equal to a lower end surface of the dense portion. In a fuel cell separator constituted by a plate having a porous portion having a resin and graphite powder as main components and a relatively dense portion,
A fuel cell separator, wherein the porous portion is formed without removing the dense portion from a mold for forming the dense portion. The fuel cell separator according to claim 7, wherein the porosity of the porous member is 5 to 60%. As the porous portion, a power generation range having a porosity of 5 to 60% having a main composition of carbon powder 235 to 2222 parts by weight with respect to resin 100 parts by weight is provided.
9. The fuel cell separator according to claim 8, wherein the dense portion includes an outer peripheral portion having a porosity of 5% or less and having a main composition of 0 to 2222 parts by weight of carbon powder based on 100 parts by weight of the resin. The fuel cell separator according to any one of claims 7 to 9, wherein a member constituting the dense portion includes a fiber base material.

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