JP2009155193A - Porous carbon sheet and method for manufacturing the same, and membrane electrode fusion product using porous carbon sheet - Google Patents
Porous carbon sheet and method for manufacturing the same, and membrane electrode fusion product using porous carbon sheet Download PDFInfo
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Abstract
Description
本発明は、固体高分子型燃料電池の電極基材として好ましく用いられる多孔質炭素板およびその製造方法に関する。さらには、多孔質炭素板を用いた膜電極融合体にも関する。 The present invention relates to a porous carbon plate preferably used as an electrode substrate of a polymer electrolyte fuel cell and a method for producing the same. Furthermore, the present invention relates to a membrane electrode fusion using a porous carbon plate.
固体高分子型燃料電池の電極基材には、導電性が高いこと、機械的強度が高いこと、好適な気体透過性を持つことなどの特性が要求される。このような特性を持つ電極の材料としては、炭素短繊維が炭素で結着された多孔質炭素板があり、その製造方法は主として抄紙工程、樹脂含浸工程、プレス工程、焼成工程に分かれている。 The electrode base material of the polymer electrolyte fuel cell is required to have characteristics such as high conductivity, high mechanical strength, and suitable gas permeability. As an electrode material having such characteristics, there is a porous carbon plate in which short carbon fibers are bound with carbon, and its manufacturing method is mainly divided into a paper making process, a resin impregnation process, a pressing process, and a firing process. .
具体的には、炭素短繊維を分散させて炭素繊維紙を抄紙し（抄紙工程）、前記炭素繊維紙をフェノール樹脂等の樹脂に含浸させる（樹脂含浸工程）。一般に、このシート状中間製品はプリプレグと呼ばれる。このプリプレグを複数積層させて加圧成形し（プレス工程）、最後に２，０００℃以上の高温で焼成（焼成工程）することにより、多孔質炭素板を得ることができる。 Specifically, carbon fiber paper is made by dispersing carbon short fibers (paper making process), and the carbon fiber paper is impregnated with a resin such as phenol resin (resin impregnation process). Generally, this sheet-like intermediate product is called a prepreg. A porous carbon plate can be obtained by laminating a plurality of the prepregs and press-molding (pressing process), and finally firing at a high temperature of 2,000 ° C. or more (firing process).
さらに、上記の工程を経て得られた多孔質炭素板に、白金等の触媒を付与し、パーフルオロスルホン酸系ポリマー等の膜をはさんで加熱加圧して一体化させたものが、膜電極融合体（ＭＥＡ）である。 Furthermore, a porous carbon plate obtained through the above steps is provided with a catalyst such as platinum, and is integrated by heating and pressurizing a membrane such as a perfluorosulfonic acid polymer to form a membrane electrode It is a fusion (MEA).
一般的に、焼成工程ではプレス工程で得た成形品を黒鉛板で挟み複数段積層して焼成を行う。積層上段部分では成形品および黒鉛板の自重により成形品へ加わる圧力が小さくなるため、積層上段部分に配置された成形品に十分な圧力を加える方法として、重しを載せる等の方法が行われている。しかし、焼成炉の容積や最大積載重量等により十分な圧力を加えられない場合がある。 In general, in the firing step, the molded product obtained in the pressing step is sandwiched between graphite plates and laminated in multiple stages for firing. Since the pressure applied to the molded product due to the weight of the molded product and the graphite plate is reduced in the upper layer part of the stack, a method such as placing a weight is performed as a method of applying sufficient pressure to the molded product arranged in the upper layer part of the stack. ing. However, there are cases where sufficient pressure cannot be applied due to the volume of the firing furnace and the maximum load weight.
このように、十分な圧力を加えずに成形品を焼成すると、多孔質炭素板の周辺部を中心にシワが発生する問題がしばしば起こっていた。シワが発生した場合、多孔質炭素板と、触媒と、電解質膜を積層して一体化したＭＥＡを製造する際、層間剥離が生じる問題があった。 As described above, when the molded product is fired without applying sufficient pressure, there is often a problem that wrinkles are generated around the periphery of the porous carbon plate. When wrinkles are generated, there is a problem that delamination occurs when an MEA in which a porous carbon plate, a catalyst, and an electrolyte membrane are laminated and integrated is produced.
このシワを抑制する方法としては、例えば特許文献１には、焼成を２段階に分離して行うこと、２ｋＰａ以上の圧力を加えて第２段階の焼成を行うことにより焼成工程でのシワの発生を抑制できることが記載されている。 As a method for suppressing this wrinkle, for example, Patent Document 1 discloses that the firing is performed in two stages, and the second stage firing is performed by applying a pressure of 2 kPa or more, thereby generating wrinkles in the firing process. It is described that can be suppressed.
しかし、特許文献１では、具体的な加圧方法は記載されておらず、多孔質電極板のどの部位に対してもシワの発生を抑制できるかまでは言及されていない。
そこで本発明の課題は、上記のような従来技術における問題点を解決し、周辺部にわたってもシワの発生が抑制された多孔質炭素板とその製造方法、さらにこの多孔質炭素板を用いた膜電極融合体を提供することにある。 Accordingly, an object of the present invention is to solve the above-described problems in the prior art, a porous carbon plate in which the generation of wrinkles is suppressed even in the peripheral portion, a manufacturing method thereof, and a film using the porous carbon plate The object is to provide an electrode fusion.
上記目的を達成するために、本発明は、（１）炭素繊維と熱硬化性樹脂とを含むシート形状のプリプレグを１枚もしくは複数枚積層させてプレス成形することで成形品を得る工程と、前記成形品を２，０００〜２，７００℃の温度で焼成して熱硬化性樹脂を炭化する焼成工程とを含む多孔質炭素板の製造方法であって、前記成形品の端部を切除してから前記焼成工程を行うことを特徴とする多孔質炭素板の製造方法を提供することにある。 In order to achieve the above object, the present invention includes (1) a step of obtaining a molded product by laminating one or a plurality of sheet-shaped prepregs containing carbon fibers and a thermosetting resin, and press molding; A method for producing a porous carbon plate, comprising a firing step of firing the molded product at a temperature of 2,000 to 2,700 ° C. to carbonize a thermosetting resin, wherein the end of the molded product is cut off. It is another object of the present invention to provide a method for producing a porous carbon plate, characterized in that the firing step is performed.
また、本発明の好ましい形態によれば、以下の発明が含まれることも好ましい態様である。
（２）焼成工程において、１，０００℃以上における焼成温度の昇温速度が０．１〜４℃／分であることを特徴とする（１）に記載の多孔質炭素板の製造方法。
（３）前記焼成工程において、成形品を複数段積層し、最上段に０．１〜１．５ｋＰａの圧力を加えて焼成を行うことを特徴とする（１）または（２）に記載の多孔質炭素板の製造方法。
（４）切除される端部の幅が２０ｍｍ〜３０ｍｍであることを特徴とする（１）から（３）のいずれかに記載の多孔質炭素板の製造方法。
（５）成形品の厚みが０．１〜０．４ｍｍであることを特徴とする（１）から（４）のいずれかに記載の多孔質炭素板の製造方法。
（６）（１）から（５）のいずれかの製造方法によって製造された多孔質炭素板。
（７）（６）に記載された多孔質炭素板と、触媒と、電解質膜とから構成された膜電極融合体。
Moreover, according to the preferable form of this invention, it is also a preferable aspect that the following invention is included.
(2) The method for producing a porous carbon plate according to (1), wherein, in the firing step, a temperature increase rate of the firing temperature at 1,000 ° C. or higher is 0.1 to 4 ° C./min.
(3) The porous structure according to (1) or (2), wherein in the firing step, a plurality of molded products are laminated, and firing is performed by applying a pressure of 0.1 to 1.5 kPa to the uppermost stage. Method for producing a carbonaceous plate.
(4) The method for producing a porous carbon plate according to any one of (1) to (3), wherein a width of an end portion to be cut is 20 mm to 30 mm.
(5) The method for producing a porous carbon plate according to any one of (1) to (4), wherein the molded product has a thickness of 0.1 to 0.4 mm.
(6) A porous carbon plate produced by the production method of any one of (1) to (5).
(7) A membrane electrode assembly comprising the porous carbon plate described in (6), a catalyst, and an electrolyte membrane.
本発明によれば、固体高分子型燃料電池に用いる電極基材の性能を低下させるシワの発生を抑制し、高品質の多孔質炭素板を大量に安定して、かつ安価に製造することができる。さらに、この多孔質炭素板を用いて、安定した性能を発現する膜電極融合体を製造することができる。 According to the present invention, it is possible to suppress the generation of wrinkles that degrade the performance of an electrode substrate used in a polymer electrolyte fuel cell, and to stably manufacture a high-quality porous carbon plate in a large amount at a low cost. it can. Furthermore, using this porous carbon plate, it is possible to produce a membrane electrode fusion product that exhibits stable performance.
本発明の多孔質炭素板とその製造方法を詳細に説明する。 The porous carbon plate of the present invention and the manufacturing method thereof will be described in detail.
多孔質炭素板の製造方法は、主として抄紙工程、樹脂含浸工程、プレス工程、焼成工程からなる。
具体的には、炭素短繊維を分散させて炭素繊維紙を抄紙し（抄紙工程）、前記炭素繊維紙をフェノール樹脂等の樹脂に含浸させる（樹脂含浸工程）。一般に、このシート状中間製品はプリプレグと呼ばれる。このプリプレグを複数積層させて加圧成形し（プレス工程）、最後に２，０００℃以上の高温で焼成（焼成工程）することにより、多孔質炭素板を得ることができる。
The method for producing a porous carbon plate mainly comprises a paper making process, a resin impregnation process, a pressing process, and a firing process.
Specifically, carbon fiber paper is made by dispersing carbon short fibers (paper making process), and the carbon fiber paper is impregnated with a resin such as phenol resin (resin impregnation process). Generally, this sheet-like intermediate product is called a prepreg. A porous carbon plate can be obtained by laminating a plurality of the prepregs and press-molding (pressing process), and finally firing at a high temperature of 2,000 ° C. or more (firing process).
最初に、抄紙工程について説明する。 First, the paper making process will be described.
本発明においては、まず炭素繊維からなる帯状のシートを準備する。 In the present invention, first, a belt-like sheet made of carbon fiber is prepared.
炭素繊維は、ポリアクリロニトリル（ＰＡＮ）系、ピッチ系、レーヨン系等の炭素繊維を用いることができる。なかでも、ＰＡＮ系やピッチ系を用いると、機械的強度に優れ、しかも、適度な柔軟性を有する電極基材が得られる点で好ましい。更には、より強度に優れ適度な柔軟性を有する電極基材が得られるという点で、特にＰＡＮ系の炭素繊維を用いるのが好ましい。 As the carbon fiber, carbon fiber such as polyacrylonitrile (PAN), pitch, or rayon can be used. Of these, use of a PAN system or a pitch system is preferable in that an electrode base material having excellent mechanical strength and appropriate flexibility can be obtained. Furthermore, it is particularly preferable to use a PAN-based carbon fiber in that an electrode base material having higher strength and appropriate flexibility can be obtained.
前記の炭素繊維を用いた炭素繊維シートの製造方法としては、乾式抄造法、湿式抄造法のいずれの方法によっても、帯状のシートを得ることができる。炭素繊維は導電性が高く、電気設備の短絡の原因になりやすい。水を抄造媒体とする湿式抄造法によると、乾式抄造法より空気中に炭素繊維が舞いにくいため簡便な装置で抄造が可能であり、しかも炭素繊維の分散性のよい均質なシートが得られる点で好ましい。なお、形態保持性やハンドリング性等を向上させるために、炭素繊維シートにポリビニルアルコール、セルロース、ポリエステル、エポキシ樹脂、フェノール樹脂、アクリル樹脂等の有機質バインダーを付与してもよい。 As a method for producing a carbon fiber sheet using the carbon fiber, a belt-like sheet can be obtained by any of a dry papermaking method and a wet papermaking method. Carbon fiber is highly conductive and tends to cause a short circuit of electrical equipment. According to the wet papermaking method using water as the papermaking medium, the carbon fiber is less likely to fly in the air than the dry papermaking method, so papermaking is possible with a simple device, and a homogeneous sheet with good carbon fiber dispersibility can be obtained. Is preferable. In addition, in order to improve form retention property, handling property, etc., you may provide organic binders, such as polyvinyl alcohol, a cellulose, polyester, an epoxy resin, a phenol resin, an acrylic resin, to a carbon fiber sheet.
続いて、樹脂含浸工程について説明する。 Subsequently, the resin impregnation step will be described.
本発明においては、樹脂含浸工程とは、得られた炭素繊維シートに連続的に熱硬化性樹脂を含浸させ、一定長さにカットして炭素繊維シートと熱硬化性樹脂の複合体であるプリプレグを得る工程を指す。 In the present invention, the resin impregnation step refers to a prepreg which is a composite of a carbon fiber sheet and a thermosetting resin by continuously impregnating the obtained carbon fiber sheet with a thermosetting resin and cutting it to a certain length. The process of obtaining.
熱硬化性樹脂としては、フェノール樹脂、エポキシ樹脂、フラン樹脂、メラミン樹脂等を用いることができる。これらの少なくとも１種を含む混合樹脂であってもよい。炭素化後も導電性物質として残存し、炭素繊維との密着性がよいものが好ましく、なかでもフェノール樹脂は炭化後の残存量が多く、扱いやすいことから好ましい。 As the thermosetting resin, phenol resin, epoxy resin, furan resin, melamine resin, or the like can be used. A mixed resin containing at least one of these may be used. Those that remain as a conductive substance after carbonization and have good adhesion to carbon fibers are preferred, and among them, a phenol resin is preferred because it has a large residual amount after carbonization and is easy to handle.
続いて、プレス工程について説明する。 Then, a press process is demonstrated.
プレス工程は、前述した樹脂含浸工程によって得られたプリプレグを加圧（プレス）成形して、成形品を得る工程を指す。プレス成形する際、含浸させた熱硬化性樹脂を硬化させるため、成形機を加温しながらプレスする方法が一般的に行われている。成形温度は、１００〜２５０℃、好ましくは１２０〜２００℃、さらに好ましくは１４０〜１８０℃とする。１００℃未満では熱硬化性樹脂が硬化しない、もしくは硬化までに時間がかかり生産性が悪くなるため好ましくない。また、２５０℃を超えると硬化までの時間が短すぎて充分に成形できず、成形品の厚さにばらつきが生じるため好ましくない。 A press process points out the process of press-molding the prepreg obtained by the resin impregnation process mentioned above, and obtaining a molded article. In order to cure the impregnated thermosetting resin at the time of press molding, a method of pressing while heating the molding machine is generally performed. The molding temperature is 100 to 250 ° C, preferably 120 to 200 ° C, more preferably 140 to 180 ° C. If it is less than 100 ° C., the thermosetting resin is not cured, or it takes time to cure and the productivity is deteriorated. On the other hand, if the temperature exceeds 250 ° C., the time until curing is too short to be sufficiently molded, and the thickness of the molded product varies, which is not preferable.
プレスする際の加圧力は、０．０１〜２ＭＰａ、好ましくは０．０５〜１．５ＭＰａ、さらに好ましくは０．１〜１ＭＰａとする。０．０１ＭＰａ未満では求める厚さの成形品ができず、２ＭＰａを超えると熱硬化性樹脂が流れ出すため好ましくない。 The pressing force at the time of pressing is 0.01 to 2 MPa, preferably 0.05 to 1.5 MPa, more preferably 0.1 to 1 MPa. If it is less than 0.01 MPa, a molded product having a desired thickness cannot be obtained, and if it exceeds 2 MPa, the thermosetting resin flows out, which is not preferable.
これにより厚さ０．１ｍｍ〜０．４ｍｍの成形品を得る。０．１mmよりも薄いと強度が低下して取り扱いにくくなる傾向があり、０．４mmよりも厚くなると、後述する焼成工程を経て多孔質炭素板としたときに厚み方向の電気抵抗が大きくなり、固体高分子型燃料電池の電極として用いたときの性能が低くなる傾向がある。なお、成形品の厚さは、成形品の厚さ方向に０．１５ＭＰａの面圧を付与した状態で、マイクロメーターを用いて測定する。 Thereby, a molded product having a thickness of 0.1 mm to 0.4 mm is obtained. When it is thinner than 0.1 mm, the strength tends to be difficult to handle, and when it is thicker than 0.4 mm, the electrical resistance in the thickness direction increases when it is made into a porous carbon plate through a firing step described later, When used as an electrode of a polymer electrolyte fuel cell, the performance tends to be low. In addition, the thickness of a molded product is measured using a micrometer in a state where a surface pressure of 0.15 MPa is applied in the thickness direction of the molded product.
ここで、本発明者らは、後述する焼成工程においてシワが発生する原因を検討したところ、樹脂含浸工程とプレス工程において基材端部への目付の偏り、すなわち中央部と比較して目付が高くなっていることを見いだした。ここで、目付とは単位面積当たりの重量のことを指す。 Here, the present inventors examined the cause of wrinkles occurring in the firing step described later, and found that the basis weight of the base material end in the resin impregnation step and the pressing step was uneven, that is, the basis weight was smaller than the center portion. I found it getting higher. Here, the basis weight refers to the weight per unit area.
この発見に基づき、焼成工程において生じるシワの原因は、焼成工程中で基材の収縮が起こる際に基材端部の目付の偏りの影響で収縮度合いが異なるとの仮定のもとで、目付が高くなっている端部を切除（トリミング）して取り除いた後に焼成工程を行うことによって、従来技術よりも少ない圧力でシワの発生が抑制された多孔質炭素板を提供できることを見いだした。 Based on this discovery, the cause of wrinkles that occur in the firing process is based on the assumption that when the substrate shrinks during the firing process, the degree of shrinkage differs due to the uneven weight of the basis weight of the substrate end. It has been found that a porous carbon plate in which the generation of wrinkles is suppressed with a pressure less than that of the prior art can be provided by performing a firing step after removing (trimming) the edge portion where the height is high.
図１に成形品の端からの距離と目付の関係を示す。端から２０mmまでは中心部に比べ目付が高くなっている。樹脂含浸工程、成形工程により目付が高くなった部分を取り除くため、得られた成形品の端部のトリミングを行う。焼成工程前のトリミングによって、焼成工程で生じる収縮度合いのバラツキを少なくし、シワの発生を防ぐことができる。また、トリミングの長さ、すなわち切除される端部の幅は端から２０〜３０mmとすることが好ましい。端から３０ｍｍまでとしたのは、端からの距離が３０ｍｍを超えると目付の差が見られず、トリミングによるシワの抑制効果に差が見られないことや、トリミング部分が増えると所定の大きさの多孔質炭素板が得られなくなるためである。 FIG. 1 shows the relationship between the distance from the end of the molded product and the basis weight. From the end to 20 mm, the basis weight is higher than the center. In order to remove the portion having a high basis weight due to the resin impregnation step and the molding step, trimming of the end portion of the obtained molded product is performed. Trimming before the firing process can reduce variations in the degree of shrinkage that occurs in the firing process and prevent wrinkles. Further, it is preferable that the trimming length, that is, the width of the end portion to be cut is 20 to 30 mm from the end. The reason why the distance from the end is 30 mm is that when the distance from the end exceeds 30 mm, there is no difference in basis weight, there is no difference in the effect of suppressing wrinkles due to trimming, and there is a predetermined size when the number of trimming portions increases. This is because the porous carbon plate cannot be obtained.
続いて、焼成工程について説明する。 Then, a baking process is demonstrated.
焼成工程は、成形品を不活性雰囲気に保たれたバッチ焼成炉で昇温し、熱硬化性樹脂を炭素化させることで導電性を向上させる工程である。これにより炭素繊維が炭素化物で結着されている多孔質炭素板を得る。 The firing step is a step of improving the conductivity by heating the molded product in a batch firing furnace maintained in an inert atmosphere and carbonizing the thermosetting resin. Thereby, a porous carbon plate in which carbon fibers are bound with a carbonized product is obtained.
焼成工程での最高焼成温度は２，０００〜２，７００℃とする。最高焼成温度が低すぎると多孔質炭素板中に不純物が多く残り、燃料電池の電極基材として用いた際に電池性能が低下する。逆に、最高焼成温度が高すぎると焼成炉の運転コストが上昇するばかりでなく、焼成炉の消耗が激しくなってその維持コストが上昇し、生産コストが上昇するようになる。 The maximum firing temperature in the firing step is 2,000 to 2,700 ° C. If the maximum firing temperature is too low, a large amount of impurities remain in the porous carbon plate, and battery performance deteriorates when used as an electrode base material for fuel cells. On the other hand, if the maximum firing temperature is too high, not only the operation cost of the firing furnace increases, but also the exhaustion of the firing furnace increases, the maintenance cost increases, and the production cost increases.
また、従来技術では形状異常は３００〜７００℃の低温領域で起こるとしているが、本発明者らは１，０００℃以上の高温領域においてより顕著に発生することを見いだし、１，０００℃以上での昇温速度を調整することでシワの発生が抑制された多孔質炭素板を提供できることを見いだした。すなわち、１，０００℃以上での昇温速度は０．１〜４℃／分とするのが好ましい。昇温速度が４℃／分を越えるように早くしすぎると、熱硬化性樹脂が急激に炭素化され著しい収縮が起こり、ひび割れやシワが生じてしまう。また、昇温速度が０．１℃／分未満のように遅くしすぎると、生産性が低下するため好ましくない。 In addition, in the prior art, the shape abnormality is assumed to occur in a low temperature region of 300 to 700 ° C., but the present inventors have found that it occurs more significantly in a high temperature region of 1,000 ° C. or higher, and is 1000 ° C. or higher. It has been found that a porous carbon plate in which the generation of wrinkles is suppressed can be provided by adjusting the rate of temperature increase. That is, it is preferable that the temperature increase rate at 1,000 ° C. or higher is 0.1 to 4 ° C./min. If the rate of temperature rise is too high so as to exceed 4 ° C./min, the thermosetting resin is abruptly carbonized, causing significant shrinkage, resulting in cracks and wrinkles. On the other hand, if the rate of temperature rise is too slow, such as less than 0.1 ° C./min, the productivity is lowered, which is not preferable.
焼成工程を行う際には、図２に示すように、複数枚の成形品２と黒鉛板１とを交互に挟み、これらを複数段積層して焼成を行う方法が一般的に用いられる。黒鉛板１は、等方性黒鉛や押出成形黒鉛で作られた黒鉛板１が用いられる。焼成時に成形品２に圧力を加えることにより、成形品２のシワ発生を効果的に抑制できる。具体的には、黒鉛板１を載せる枚数を増減させながら、成形品２の最上段に０．１〜１．５ｋＰａの圧力が加わるようにする。圧力が０．１ｋＰａ未満であると、シワ抑制の効果が十分でないことが多い。また、１．５ｋＰａを越えると、加圧用の重しとなる黒鉛板１の枚数が増え、焼成炉の容積や最大積載重量を超える恐れがあったり、成形品２の積載量が制限されたりするため、却って生産効率が落ちることになりやすい。 When performing the firing step, as shown in FIG. 2, a method is generally used in which a plurality of molded products 2 and graphite plates 1 are alternately sandwiched and fired by laminating a plurality of stages. As the graphite plate 1, a graphite plate 1 made of isotropic graphite or extruded graphite is used. By applying pressure to the molded product 2 during firing, wrinkling of the molded product 2 can be effectively suppressed. Specifically, a pressure of 0.1 to 1.5 kPa is applied to the uppermost stage of the molded product 2 while increasing or decreasing the number of sheets on which the graphite plate 1 is placed. If the pressure is less than 0.1 kPa, the effect of suppressing wrinkles is often insufficient. On the other hand, when the pressure exceeds 1.5 kPa, the number of graphite plates 1 serving as a weight for pressurization increases, which may exceed the capacity of the firing furnace and the maximum loading weight, or the loading capacity of the molded product 2 is limited. For this reason, production efficiency tends to decrease.
以上の工程を経て得られた多孔質炭素板は、電極基材として使用される。具体的には、多孔質炭素板に触媒を付与し、フッ素系ポリマー等の電解質膜を挟んで一体化させた膜電極融合体（ＭＥＡ）となって、燃料電池の電極として用いられる。 The porous carbon plate obtained through the above steps is used as an electrode substrate. Specifically, a catalyst is applied to a porous carbon plate, and a membrane electrode assembly (MEA) in which an electrolyte membrane such as a fluoropolymer is sandwiched and integrated is used as an electrode of a fuel cell.
ここで、触媒には、カーボンブラック担体上に白金触媒やルテニウム・白金合金触媒を担持したものがよく用いられ、電解質膜としてはパーフルオロスルホン酸系ポリマーが好んで用いられる。 Here, a catalyst in which a platinum catalyst or a ruthenium / platinum alloy catalyst is supported on a carbon black carrier is often used, and a perfluorosulfonic acid polymer is preferably used as the electrolyte membrane.
（実施例１）
東レ株式会社製ポリアクリロニトリル系炭素繊維“トレカ（登録商標）”Ｔ３００−６Ｋ（平均繊維径：７μｍ、単繊維数：６，０００本）を１２ｍｍの長さにカットし、水を抄造媒体として、ポリビニルアルコールをバインダーとして連続的に抄造し、シートの目付が約３０ｇ／ｍ２で幅１０００mmの炭素繊維シートを得てロール状に巻き取った。
Example 1
Toray Co., Ltd. polyacrylonitrile-based carbon fiber “Torayca (registered trademark)” T300-6K (average fiber diameter: 7 μm, number of single fibers: 6,000) was cut to a length of 12 mm, and water was used as a papermaking medium. Paper was continuously made using polyvinyl alcohol as a binder, and a carbon fiber sheet having a basis weight of about 30 g / m 2 and a width of 1000 mm was obtained and wound into a roll.
次に炭素繊維シートにレゾール型フェノール樹脂とノボラック型フェノール樹脂を１：１の重量比で混合した樹脂の６重量％メタノール溶液に連続的に含浸し、９０℃で３分間加熱乾燥した後１，０００mmの長さにカットし、シート状のプリプレグを得た。 Next, the carbon fiber sheet was continuously impregnated with a 6% by weight methanol solution of a resin in which a resole type phenolic resin and a novolac type phenolic resin were mixed at a weight ratio of 1: 1, dried by heating at 90 ° C. for 3 minutes, The sheet was cut to a length of 000 mm to obtain a sheet-like prepreg.
次に得られたプリプレグを２枚重ねて、１４５℃の温度下に０．４５ＭＰａの圧力を３０分間加えてレゾール型フェノール樹脂を硬化させ、成形品を得た。 Next, two prepregs obtained were stacked and a resol type phenolic resin was cured by applying a pressure of 0.45 MPa at a temperature of 145 ° C. for 30 minutes to obtain a molded product.
成形品の端部４辺を２０ｍｍトリミングし、積層した最上段の成形品に０．５ｋＰａの圧力が加わるようにした。そして最高温度２，５００℃として１，０００℃以上の昇温速度を０．５℃／分で焼成し、樹脂を炭化させ厚さ０．２mmの多孔質炭素板を得た。
（実施例２）
焼成時に積層した最上段の成形品に１．０ｋＰａの圧力が加わるようにすること以外は実施例１と同様にして多孔質炭素板を得た。
（比較例１）
成形品の端部４辺をトリミングしないこと以外は実施例１と同様にして多孔質炭素板を得た。
（比較例２）
成形品の端部４辺をトリミングせず、焼成時に積層した最上段の成形品に１．０ｋＰａの圧力が加わるようにすること以外は実施例１と同様にして多孔質炭素板を得た。
The four edges of the molded product were trimmed by 20 mm so that a pressure of 0.5 kPa was applied to the laminated uppermost molded product. A maximum temperature of 2,500 ° C. was fired at a heating rate of 1,000 ° C. or higher at 0.5 ° C./min to carbonize the resin to obtain a porous carbon plate having a thickness of 0.2 mm.
(Example 2)
A porous carbon plate was obtained in the same manner as in Example 1 except that a pressure of 1.0 kPa was applied to the uppermost molded product laminated at the time of firing.
(Comparative Example 1)
A porous carbon plate was obtained in the same manner as in Example 1 except that the end 4 sides of the molded product were not trimmed.
(Comparative Example 2)
A porous carbon plate was obtained in the same manner as in Example 1 except that the end 4 sides of the molded product were not trimmed and a pressure of 1.0 kPa was applied to the uppermost molded product laminated during firing.
以上の実施例および比較例について、それぞれ１，０００枚製造した場合において、シワが発生した多孔質炭素板の枚数から、下記の式を用いてシワ発生率を算出した。 For each of the above Examples and Comparative Examples, when 1,000 sheets were produced, the wrinkle generation rate was calculated from the number of the porous carbon plates where wrinkles were generated using the following formula.
シワ発生率（％）＝シワが発生した多孔質炭素板の枚数／１，０００×１００
多孔質炭素板のシワ発生率および発生したシワの最大長さを表１にまとめた。
Wrinkle generation rate (%) = number of porous carbon plates with wrinkles / 1,000 × 100
Table 1 shows the wrinkle generation rate of the porous carbon plate and the maximum length of the generated wrinkles.
表１に示されるとおり、本発明の製造方法により比較例の製造方法に比べてシワ発生率を大幅に低減させることが可能となった。さらに、発生するシワの最大長さも大幅に改善され、有効活用できる面積が増加した。 As shown in Table 1, the production method of the present invention can significantly reduce the wrinkle generation rate as compared with the production method of the comparative example. In addition, the maximum length of wrinkles that occur is greatly improved, and the area that can be used effectively has increased.
以上のように本発明の多孔質炭素板の製造方法によれば、燃料電池の電極板としての性能を低下させる形状異常であるシワの発生を抑制し、高品質の多孔質炭素板を大量に安定して、かつ安価に製造することができる。 As described above, according to the method for producing a porous carbon plate of the present invention, the generation of wrinkles, which are abnormal shapes that reduce the performance as an electrode plate of a fuel cell, is suppressed, and a large number of high-quality porous carbon plates are produced. It can be manufactured stably and inexpensively.
本発明に係る多孔質炭素板は、固体高分子型燃料電池のガス拡散体に限らず、燐酸型燃料電池などにも応用することができるが、その応用範囲はこれらに限られるものではない。 The porous carbon plate according to the present invention can be applied not only to a gas diffuser of a solid polymer fuel cell but also to a phosphoric acid fuel cell, but the application range is not limited thereto.
１：黒鉛板
２：成形品
1: Graphite plate 2: Molded product
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014127310A (en) * | 2012-12-26 | 2014-07-07 | Mitsubishi Rayon Co Ltd | Method for producing porous electrode base material precursor sheet, and porous electrode base material precursor sheet |
| JP2015071508A (en) * | 2013-10-03 | 2015-04-16 | 三菱レイヨン株式会社 | Method of producing porous electrode substrate |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014127310A (en) * | 2012-12-26 | 2014-07-07 | Mitsubishi Rayon Co Ltd | Method for producing porous electrode base material precursor sheet, and porous electrode base material precursor sheet |
| JP2015071508A (en) * | 2013-10-03 | 2015-04-16 | 三菱レイヨン株式会社 | Method of producing porous electrode substrate |
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