JP4974700B2 - Carbon fiber sheet and manufacturing method thereof - Google Patents
Carbon fiber sheet and manufacturing method thereof Download PDFInfo
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- JP4974700B2 JP4974700B2 JP2007040040A JP2007040040A JP4974700B2 JP 4974700 B2 JP4974700 B2 JP 4974700B2 JP 2007040040 A JP2007040040 A JP 2007040040A JP 2007040040 A JP2007040040 A JP 2007040040A JP 4974700 B2 JP4974700 B2 JP 4974700B2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Description
本発明は、炭素繊維シート及びその製造方法に関し、更に詳しくは多孔質な形状で、弾性があり、柔軟性に富み、取扱性の良い固体高分子型燃料電池ガス拡散層用炭素繊維シート及びその製造方法に関する。 The present invention relates to a carbon fiber sheet and a method for producing the same, and more specifically, a porous shape, elasticity, flexibility, and handling property of a carbon fiber sheet for a polymer electrolyte fuel cell gas diffusion layer and good handling properties thereof. It relates to a manufacturing method.
従来の固体高分子型燃料電池用ガス拡散層に用いる炭素繊維シートは、電池性能を向上させるために、燃料気体を拡散させるよう多孔質な形状となっている。ただし、多孔質であるがゆえに強度が低く、柔軟性に乏しく、取扱いが困難であるなどの問題がある。この問題に対し、種々の提案がされている(例えば、特許文献1、2参照)。 A conventional carbon fiber sheet used for a gas diffusion layer for a polymer electrolyte fuel cell has a porous shape so as to diffuse fuel gas in order to improve battery performance. However, since it is porous, there are problems such as low strength, poor flexibility, and difficulty in handling. Various proposals have been made for this problem (see, for example, Patent Documents 1 and 2).
特許文献1では、ポリビニルピロリドン(PVP)樹脂に黒鉛を配合し、酸化安定化させたPVPをバインダとして使用することにより、取扱性の良い多孔質シートを提供することが提案されている。しかし、このシートは柔軟性が高すぎるために、セルに組み込んだ際にセパレータの溝に垂れ込み、電池性能が低下する。 In Patent Document 1, it is proposed to provide a porous sheet with good handleability by using PVP blended with polyvinyl pyrrolidone (PVP) resin and oxidized and stabilized as a binder. However, since this sheet is too flexible, it sags into the groove of the separator when assembled in a cell, and the battery performance decreases.
特許文献2では、炭素繊維同士を接合するバインダとして、ポリビニルアルコール(PVA)樹脂、ポリエステル樹脂、エポキシ樹脂、フェノール樹脂、アクリル樹脂等を使用し、その樹脂に黒鉛を配合させることにより、強度の高い多孔質シートを提供することが提案されている。しかし、この場合は柔軟性の改善が不充分である。
本発明者は、上記問題について鋭意検討しているうち、炭素粒子を含み前記炭素繊維同士の交差部を接合する無定形炭素とからなる固体高分子型燃料電池ガス拡散層用炭素繊維シートであって、無定形炭素含有量(B)と炭素粒子含有量(C)との合計に対する炭素粒子含有量(C)の質量比[C/(B+C)]と、炭素繊維含有量(A)に対する無定形炭素含有量(B)と炭素粒子含有量(C)との合計の質量比[(B+C)/A]とを、それぞれ所定範囲にすることで、柔軟性が付与された炭素繊維シートを得ることができ、その生産時の工程安定性が改善できることを見出し、本発明を完成するに到った。 The present inventor has intensively studied the above problem and is a carbon fiber sheet for a polymer electrolyte fuel cell gas diffusion layer composed of amorphous carbon containing carbon particles and joining the intersections of the carbon fibers. The mass ratio [C / (B + C)] of the carbon particle content (C) to the sum of the amorphous carbon content (B) and the carbon particle content (C) and the carbon fiber content (A) By making the total mass ratio [(B + C) / A] of the regular carbon content (B) and the carbon particle content (C) within a predetermined range, a carbon fiber sheet with flexibility is obtained. It has been found that the process stability during production can be improved, and the present invention has been completed.
従って、本発明の目的とするところは、上記問題を解決した、多孔質な形状で、弾性があり、柔軟性に富み、取扱性の良い固体高分子型燃料電池ガス拡散層用炭素繊維シート及びその製造方法を提供することにある。 Accordingly, the object of the present invention is to solve the above-mentioned problems, and has a porous shape, elasticity, flexibility and good handling properties, and a carbon fiber sheet for a polymer electrolyte fuel cell gas diffusion layer having good handling properties and It is in providing the manufacturing method.
上記目的を達成する本発明は、以下に記載のものである。 The present invention for achieving the above object is as follows.
[1] 炭素繊維と、炭素粒子を含み前記炭素繊維同士の交差部を接合する無定形炭素とからなる固体高分子型燃料電池ガス拡散層用炭素繊維シートであって、無定形炭素含有量(B)と炭素粒子含有量(C)との合計に対する炭素粒子含有量(C)の質量比[C/(B+C)]が0.65〜0.95であり且つ炭素繊維含有量(A)に対する無定形炭素含有量(B)と炭素粒子含有量(C)との合計の質量比[(B+C)/A]が1.50〜5.00である固体高分子型燃料電池ガス拡散層用炭素繊維シート。 [1] A carbon fiber sheet for a polymer electrolyte fuel cell gas diffusion layer comprising carbon fibers and amorphous carbon containing carbon particles and joining the intersections of the carbon fibers, wherein the amorphous carbon content ( The mass ratio [C / (B + C)] of the carbon particle content (C) to the sum of B) and the carbon particle content (C) is 0.65 to 0.95 and is relative to the carbon fiber content (A). Solid polymer fuel cell gas diffusion layer carbon having a total mass ratio [(B + C) / A] of the amorphous carbon content (B) and the carbon particle content (C) of 1.50 to 5.00 Fiber sheet.
[2] 厚さが100〜350μm、目付が40〜200g/m2である[1]に記載の固体高分子型燃料電池ガス拡散層用炭素繊維シート。 [2] The carbon fiber sheet for a polymer electrolyte fuel cell gas diffusion layer according to [1], having a thickness of 100 to 350 μm and a basis weight of 40 to 200 g / m 2 .
[3] 炭素粒子が、黒鉛粒子又はカーボンブラックである[1]に記載の固体高分子型燃料電池ガス拡散層用炭素繊維シート。 [3] The carbon fiber sheet for a polymer electrolyte fuel cell gas diffusion layer according to [1], wherein the carbon particles are graphite particles or carbon black.
[4] [1]に記載の炭素繊維シートで形成されてなる固体高分子型燃料電池用ガス拡散層。 [4] A gas diffusion layer for a polymer electrolyte fuel cell formed of the carbon fiber sheet according to [1].
[5] 炭素繊維を抄紙して得た原料炭素繊維ペーパーに、添着用樹脂と炭素粒子との混合物を、最終工程の炭素化処理工程後に、無定形炭素含有量(B)と炭素粒子含有量(C)との合計に対する炭素粒子含有量(C)の質量比[C/(B+C)]が0.65〜0.95となり且つ炭素繊維含有量(A)に対する無定形炭素含有量(B)と炭素粒子含有量(C)との合計の質量比[(B+C)/A]が1.50〜5.00となる量、添着した後、空気中、温度150℃〜400℃、圧力0.1〜1.8MPaで酸化安定化処理し、次いで、不活性ガス中、温度1500〜2500℃で炭素化処理することを特徴とする、炭素繊維と、炭素粒子を含み前記炭素繊維同士の交差部を接合する無定形炭素とからなる固体高分子型燃料電池ガス拡散層用炭素繊維シートの製造方法。 [5] A raw material carbon fiber paper obtained by papermaking carbon fiber is mixed with a resin and carbon particles, and after the final carbonization treatment step, amorphous carbon content (B) and carbon particle content The mass ratio [C / (B + C)] of the carbon particle content (C) to the sum of (C) is 0.65 to 0.95 and the amorphous carbon content (B) relative to the carbon fiber content (A) And the carbon particle content (C) are added in such an amount that the total mass ratio [(B + C) / A] is 1.50 to 5.00, and then in air, the temperature is 150 ° C. to 400 ° C., the pressure is 0. Oxidation stabilization treatment at 1 to 1.8 MPa, followed by carbonization treatment at a temperature of 1500 to 2500 ° C. in an inert gas, and a carbon fiber containing carbon particles and an intersection of the carbon fibers Of carbon fiber sheet for solid polymer fuel cell gas diffusion layer comprising amorphous carbon joining .
[6] 添着用樹脂が、尿素樹脂、メラミン樹脂、フェノール樹脂、ポリビニルピロリドン樹脂、及び、カルボキシメチルセルロース樹脂からなるグループから選ばれる樹脂である[5]に記載の固体高分子型燃料電池ガス拡散層用炭素繊維シートの製造方法。 [6] The polymer electrolyte fuel cell gas diffusion layer according to [5], wherein the resin to be attached is a resin selected from the group consisting of a urea resin, a melamine resin, a phenol resin, a polyvinylpyrrolidone resin, and a carboxymethylcellulose resin. Of manufacturing carbon fiber sheet for use in a vehicle.
本発明の炭素繊維シートは、所定の範囲で炭素粒子を含む無定形炭素で炭素繊維同士の交差部を接合しているので、この炭素繊維シートに外圧が負荷された場合、適度に交差部の接合が破壊されて、破壊が炭素繊維シート全体に及ばない。その結果、本炭素繊維シートは、弾性があり、柔軟性に富み、取扱性が良い。このことから、本発明の炭素繊維シートは、固体高分子型燃料電池ガス拡散層用として適している。 Since the carbon fiber sheet of the present invention joins the intersection of carbon fibers with amorphous carbon containing carbon particles within a predetermined range, when an external pressure is applied to the carbon fiber sheet, the intersection of the carbon fiber is moderately The bond is broken and the break does not reach the entire carbon fiber sheet. As a result, the present carbon fiber sheet is elastic, rich in flexibility and easy to handle. Therefore, the carbon fiber sheet of the present invention is suitable for a polymer electrolyte fuel cell gas diffusion layer.
本発明の炭素繊維シートの製造方法によれば、所定量の炭素粒子を含有する樹脂を炭素繊維ペーパーに添着する簡単な操作で、弾性があり、柔軟性に富み、取扱性が良い炭素繊維シートを製造することができる。 According to the method for producing a carbon fiber sheet of the present invention, the carbon fiber sheet is elastic, flexible, and easy to handle by a simple operation of attaching a resin containing a predetermined amount of carbon particles to carbon fiber paper. Can be manufactured.
以下、本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail.
図1は、本発明の炭素繊維シートの一例を示す概念断面図で、その断面はシートの厚み方向に沿った面である。 FIG. 1 is a conceptual cross-sectional view showing an example of the carbon fiber sheet of the present invention, and the cross section is a surface along the thickness direction of the sheet.
図1に例示するように、炭素繊維シート2は、固体高分子型燃料電池ガス拡散層用の炭素繊維シートであり、炭素繊維4と、炭素粒子6を含み前記炭素繊維4同士の交差部を接合する無定形炭素8とからなる。10は、無定形炭素8又は炭素粒子6の間で形成される間隙である。
As illustrated in FIG. 1, the carbon fiber sheet 2 is a carbon fiber sheet for a polymer electrolyte fuel cell gas diffusion layer. The carbon fiber sheet 2 includes
炭素繊維4は、二次元平面内において無作為な方向に分散しているので、断面が繊維軸に直交する面の場合は、繊維の断面形状は円になり、断面が繊維軸に斜めになる面の場合は、繊維の断面形状は楕円になる。炭素繊維4は、繊維径3〜30μmのものが好ましい。
Since the
炭素繊維シート2において、炭素繊維4含有量(A)、無定形炭素8含有量(B)、炭素粒子6含有量(C)は、以下の測定例に示す方法により求められる。
In the carbon fiber sheet 2, the
図1に示すように、顕微鏡で1200倍に拡大した炭素繊維シート2の厚み方向に沿った断面を幅1mm、高さ約0.2〜0.3mm分撮影する。この断面写真を画像解析し、炭素繊維4、無定形炭素8、炭素粒子6及び空隙10を識別し、それぞれの面積を測定する。
As shown in FIG. 1, the cross section along the thickness direction of the carbon fiber sheet 2 magnified 1200 times with a microscope is photographed for 1 mm in width and about 0.2 to 0.3 mm in height. This cross-sectional photograph is image-analyzed, the
この面積測定を5ヶ所の撮影ヶ所について行う。5ヶ所の測定について、炭素繊維4、無定形炭素8、炭素粒子6の平均の面積を求め、それぞれSA、SB、SCとする。加えて、それぞれの比重ρA、ρB、ρCと、測定したシート目付W[g/m2]を用いて、炭素繊維含有量(A)、無定形炭素含有量(B)、炭素粒子含有量(C)を以下の式
炭素繊維含有量[g/m2]:(A)=W×SAρA/(SAρA+SBρB+SCρC)
無定形炭素含有量[g/m2]:(B)=W×SBρB/(SAρA+SBρB+SCρC)
炭素粒子含有量[g/m2]:(C)=W×SCρC/(SAρA+SBρB+SCρC)
(ここで、炭素繊維、無定形炭素、炭素粒子の比重は、それぞれ以下の値:
ρA=1.78、ρB=2.20、ρC=2.00
を用いる)
により算出する。
This area measurement is performed at 5 shooting locations. About five locations measurement,
Amorphous carbon content [g / m 2 ]: (B) = W × S B ρ B / (S A ρ A + S B ρ B + S C ρ C )
Carbon particle content [g / m 2 ]: (C) = W × S C ρ C / (S A ρ A + S B ρ B + S C ρ C )
(Here, the specific gravity of carbon fiber, amorphous carbon, and carbon particles is as follows:
ρ A = 1.78, ρ B = 2.20, ρ C = 2.00
Used)
Calculated by
本発明の炭素繊維シートは、無定形炭素含有量(B)と炭素粒子含有量(C)との合計に対する炭素粒子含有量(C)の質量比[C/(B+C)]が0.65〜0.95であり、0.70〜0.95であることがより好ましい。且つ、炭素繊維含有量(A)に対する無定形炭素含有量(B)と炭素粒子含有量(C)との合計の質量比[(B+C)/A]が1.5〜5.0であり、1.6〜4.8であることがより好ましい。 In the carbon fiber sheet of the present invention, the mass ratio [C / (B + C)] of the carbon particle content (C) to the sum of the amorphous carbon content (B) and the carbon particle content (C) is 0.65. 0.95, more preferably 0.70 to 0.95. And the total mass ratio [(B + C) / A] of the amorphous carbon content (B) and the carbon particle content (C) to the carbon fiber content (A) is 1.5 to 5.0, More preferably, it is 1.6 to 4.8.
質量比[C/(B+C)]が0.65未満の場合、炭素繊維シートの曲げ撓み量が不足し、また曲げ弾性率が高くなりすぎることがある。質量比[C/(B+C)]が0.95を超える場合、炭素繊維シートの曲げ撓み量が不足し、また嵩密度が高すぎて、通気性、通水性が悪くなることがある。 When the mass ratio [C / (B + C)] is less than 0.65, the amount of bending bending of the carbon fiber sheet may be insufficient, and the bending elastic modulus may be too high. When the mass ratio [C / (B + C)] exceeds 0.95, the amount of bending deflection of the carbon fiber sheet may be insufficient, and the bulk density may be too high, resulting in poor air permeability and water permeability.
質量比[(B+C)/A]が1.5未満の場合、曲げ撓み量が不足し、また曲げ強度が低下することがある。質量比[(B+C)/A]が5.0を超える場合、炭素粒子が無定形炭素や炭素繊維に付着せず、それらから脱落し易くなり、炭素繊維シートの曲げ撓み量が不足し、また曲げ強度が低下することがある。 When the mass ratio [(B + C) / A] is less than 1.5, the bending deflection amount may be insufficient and the bending strength may be reduced. When the mass ratio [(B + C) / A] exceeds 5.0, the carbon particles do not adhere to the amorphous carbon or the carbon fibers and easily fall off from them, and the bending deflection amount of the carbon fiber sheet is insufficient. Bending strength may decrease.
炭素繊維シートは、曲げ弾性率が1〜5GPaであり、1.1〜4.6GPaであることがより好ましい。曲げ弾性率が1GPa未満の場合、炭素繊維シートは柔軟すぎて、炭素繊維シートをガス拡散層として用い、これにセパレータをセットして固体高分子型燃料電池の単セルを形成する際に表面の平滑性が低下する。曲げ弾性率が5GPaを超える場合、曲げ弾性率が高くなりすぎて柔軟性が失われ、ロールへの巻取りが出来なくなる。 The carbon fiber sheet has a flexural modulus of 1 to 5 GPa, more preferably 1.1 to 4.6 GPa. When the flexural modulus is less than 1 GPa, the carbon fiber sheet is too flexible, the carbon fiber sheet is used as a gas diffusion layer, and a separator is set on the carbon fiber sheet to form a single cell of a polymer electrolyte fuel cell. Smoothness decreases. When the flexural modulus exceeds 5 GPa, the flexural modulus becomes too high, the flexibility is lost, and the roll cannot be wound.
炭素繊維シートは、曲げ撓み量が2〜6mmであり、2.3〜5mmであることがより好ましい。曲げ撓み量が2mm未満の場合、曲げ撓み量が6mmを超える場合、取扱性が悪くなり、また柔らかすぎてセパレータセット時にセパレータの溝に落ち込む。 The amount of bending deflection of the carbon fiber sheet is 2 to 6 mm, and more preferably 2.3 to 5 mm. When the amount of bending deflection is less than 2 mm, when the amount of bending deflection exceeds 6 mm, the handleability deteriorates, and it is too soft and falls into the separator groove when the separator is set.
炭素繊維シートは、厚さが100〜350μmであることが好ましく、150〜290μmであることがより好ましい。厚さが100μm未満の場合、炭素繊維シートの総強力が低く、折れたり、割れやすい。厚さが350μmを超える場合、厚さ方向の通電性が低下する。更には、単セルの厚みが増大し、スタックにセットする単セルの枚数が少なくなり、固体高分子型燃料電池のキャパシティーが低下する。 The carbon fiber sheet preferably has a thickness of 100 to 350 μm, and more preferably 150 to 290 μm. When the thickness is less than 100 μm, the total strength of the carbon fiber sheet is low, and the carbon fiber sheet is easily broken or broken. When the thickness exceeds 350 μm, the conductivity in the thickness direction decreases. Furthermore, the thickness of the single cell increases, the number of single cells set in the stack decreases, and the capacity of the polymer electrolyte fuel cell decreases.
炭素繊維シートは、目付が40〜200g/m2であることが好ましく、70〜150g/m2であることがより好ましい。目付が40〜200g/m2未満の場合、引張り強度が低く、後加工時の工程で切断等が発生する。目付が40〜200g/m2を超える場合、所期の厚さのシートを作ることが困難である。 The carbon fiber sheet preferably has a basis weight of 40 to 200 g / m 2 , and more preferably 70 to 150 g / m 2 . When the basis weight is less than 40 to 200 g / m 2 , the tensile strength is low, and cutting or the like occurs in the post-processing step. When the basis weight exceeds 40 to 200 g / m 2 , it is difficult to make a sheet having a desired thickness.
炭素繊維シートは、嵩密度が0.3〜0.7g/cm3であることが好ましく、0.35〜0.66g/cm3であることがより好ましい。嵩密度が0.3g/cm3未満の場合、所期の弾性率が出にくい。嵩密度が0.7g/cm3を超える場合、目が詰まりすぎて排水性やガス透過性が低下する。 The carbon fiber sheet preferably has a bulk density of 0.3 to 0.7 g / cm 3 , and more preferably 0.35 to 0.66 g / cm 3 . When the bulk density is less than 0.3 g / cm 3 , the desired elastic modulus is difficult to be obtained. When the bulk density exceeds 0.7 g / cm 3 , the eyes are clogged too much and drainage and gas permeability are deteriorated.
炭素繊維シートは、電気抵抗値が200mΩ・cm2以下であることが好ましい。電気抵抗値が200mΩ・cm2を超えると、通電性が悪く、電極材としての応用が困難である。 The carbon fiber sheet preferably has an electric resistance value of 200 mΩ · cm 2 or less. When the electrical resistance value exceeds 200 mΩ · cm 2 , the electrical conductivity is poor and application as an electrode material is difficult.
炭素繊維シートは、電池特性が0.6V以上(at 0.6mA/cm2)であることが好ましい。電池特性が0.6V未満の場合は、良好な発電性能が得られ無い為、好ましくない。 The carbon fiber sheet preferably has a battery characteristic of 0.6 V or more (at 0.6 mA / cm 2 ). A battery characteristic of less than 0.6 V is not preferable because good power generation performance cannot be obtained.
[炭素繊維シートの製造方法]
本発明の炭素繊維シートは、その物性が上記範囲内にあれば、その製造方法としては、特に限定されるものではないが、例えば、炭素繊維を抄紙して得た原料炭素繊維ペーパーに、添着用樹脂と炭素粒子との混合物を、最終工程の炭素化処理工程後に、無定形炭素含有量(B)と炭素粒子含有量(C)との合計に対する炭素粒子含有量(C)の質量比[C/(B+C)]が0.65〜0.95となり且つ炭素繊維含有量(A)に対する無定形炭素含有量(B)と炭素粒子含有量(C)との合計の質量比[(B+C)/A]が1.50〜5.00となる量、添着した後、空気中、温度150℃〜400℃、圧力0.1〜1.8MPaで酸化安定化処理し、次いで、不活性ガス中、温度1500〜2500℃で炭素化処理することにより製造することができる。
[Method for producing carbon fiber sheet]
The carbon fiber sheet of the present invention is not particularly limited as long as its physical properties are within the above range. For example, the carbon fiber sheet is added to the raw carbon fiber paper obtained by papermaking carbon fiber. The mass ratio of the carbon particle content (C) to the total of the amorphous carbon content (B) and the carbon particle content (C) after the carbonization treatment step of the final step is performed on the mixture of the wearing resin and the carbon particles [ C / (B + C)] is 0.65 to 0.95, and the total mass ratio of the amorphous carbon content (B) and the carbon particle content (C) to the carbon fiber content (A) [(B + C) / A] is added in an amount of 1.50 to 5.00, and then subjected to oxidation stabilization treatment in air at a temperature of 150 ° C. to 400 ° C. and a pressure of 0.1 to 1.8 MPa, and then in an inert gas. It can manufacture by carrying out carbonization treatment at the temperature of 1500-2500 degreeC.
[原料炭素繊維ペーパー]
必要に応じ繊維長2〜20mmにカットした繊維径3〜30μmの炭素繊維を抄紙して得られるペーパーであり、厚さが100〜400μm、目付が40〜200g/m2であることが好ましい。この炭素繊維ペーパーは、複数枚を積層したものでもよい。
[Raw material carbon fiber paper]
It is a paper obtained by making a carbon fiber having a fiber diameter of 3 to 30 μm cut to a fiber length of 2 to 20 mm as necessary, and preferably has a thickness of 100 to 400 μm and a basis weight of 40 to 200 g / m 2 . This carbon fiber paper may be a laminate of a plurality of sheets.
炭素繊維ペーパーを構成する繊維原料としてはポリアクリロニトリル(PAN)系炭素繊維、ピッチ系炭素繊維など従来公知の何れの炭素繊維でも用いることができる。上記炭素繊維のうちでも、酸化安定化処理、炭素化処理を行う上では、強度、伸度の比較的高いPAN系炭素繊維が最も好適である。 As a fiber raw material constituting the carbon fiber paper, any conventionally known carbon fiber such as polyacrylonitrile (PAN) -based carbon fiber and pitch-based carbon fiber can be used. Among the carbon fibers, PAN-based carbon fibers having relatively high strength and elongation are most suitable for performing oxidation stabilization treatment and carbonization treatment.
[添着用樹脂と炭素粒子との混合物の添着]
上記炭素繊維には、添着用樹脂と炭素粒子との混合物を、上記配合量、添着させる。原料炭素繊維ペーパーに添着用樹脂と炭素粒子との混合物を添着させる方法としては、ペーパー作製時に添着用樹脂と炭素粒子との混合物を混合させる方法、ペーパー作製後に添着用樹脂と炭素粒子との混合物を含浸させる方法、ペーパー作製後にスプレーで添着用樹脂と炭素粒子との混合物を噴霧させることにより添着させる方法、ペーパー作製後に添着用樹脂と炭素粒子との混合物をコーティングさせる方法などがある。
[Adhesion of a mixture of resin and carbon particles for attachment]
A mixture of the resin to be attached and the carbon particles is attached to the carbon fiber in the above-mentioned blending amount. The method of adhering the mixture of the resin to be attached and carbon particles to the raw carbon fiber paper is a method of mixing the mixture of the resin to be attached and carbon particles at the time of making the paper, the mixture of the resin to be attached and carbon particles after making the paper There are a method of impregnating the resin, a method of applying by spraying a mixture of the resin to be attached and carbon particles after spraying, and a method of coating the mixture of the resin to be attached and carbon particles after preparing the paper.
[添着用樹脂の種類]
添着用樹脂は、尿素樹脂、メラミン樹脂、フェノール樹脂、PVP樹脂、及び、カルボキシメチルセルロース(CMC)樹脂からなるグループから選ばれる樹脂であることが好ましい。
[Types of attached resin]
The attaching resin is preferably a resin selected from the group consisting of a urea resin, a melamine resin, a phenol resin, a PVP resin, and a carboxymethyl cellulose (CMC) resin.
[炭素粒子の平均粒径]
炭素粒子の平均粒径は、0.4〜30μmであることが好ましい。炭素粒子の平均粒径が0.4μm未満の場合は、溶液中で凝集し分散斑が置きやすい。炭素粒子の平均粒径が30μmを超える場合は、炭素粒子がシート内部まで入らない。
[Average particle size of carbon particles]
The average particle size of the carbon particles is preferably 0.4 to 30 μm. When the average particle diameter of the carbon particles is less than 0.4 μm, the carbon particles are aggregated in the solution and dispersion spots are easily placed. When the average particle diameter of the carbon particles exceeds 30 μm, the carbon particles do not enter the sheet.
[炭素粒子の種類]
炭素粒子としては、鱗片状黒鉛、鱗状黒鉛、土状黒鉛、人造黒鉛、膨張黒鉛、膨張化黒鉛、葉片状黒鉛、塊状黒鉛、球状黒鉛などの黒鉛粒子、更には、カーボンブラック、フラーレン、カーボンナノチューブなどが挙げられる。特に限定はされないが、上記炭素粒子のうちでも、黒鉛粒子、カーボンブラックがより好ましい。
[Types of carbon particles]
Carbon particles include graphite particles such as flaky graphite, flaky graphite, earthy graphite, artificial graphite, expanded graphite, expanded graphite, flake graphite, massive graphite, and spherical graphite, and also carbon black, fullerene, carbon And nanotubes. Although not particularly limited, among the carbon particles, graphite particles and carbon black are more preferable.
[添着用樹脂と炭素粒子の添着量]
樹脂添着量については、原料炭素繊維ペーパー目付(抄紙バインダを含む)の1.5〜9.0倍が好ましい。なお、通常の抄紙バインダの含有量は、炭素繊維ペーパーに対して0.1〜0.2倍である。
[Amount of resin and carbon particles attached]
The resin adhering amount is preferably 1.5 to 9.0 times the raw carbon fiber paper weight (including the papermaking binder). In addition, content of a normal papermaking binder is 0.1 to 0.2 times with respect to carbon fiber paper.
添着用樹脂と炭素粒子の添着量については、酸化安定化処理前の質量に対する炭素化処理後の質量で示される収率に応じて、最終工程の炭素化処理工程後における無定形炭素含有量(B)と炭素粒子含有量(C)との質量比[C/(B+C)]で0.65〜0.95の量となるように適宜調節することが好ましい。 About the amount of resin and carbon particles to be attached, the amorphous carbon content after the carbonization treatment step of the final step according to the yield indicated by the mass after the carbonization treatment relative to the mass before the oxidation stabilization treatment ( It is preferable that the mass ratio [C / (B + C)] between B) and the carbon particle content (C) is appropriately adjusted so as to be an amount of 0.65 to 0.95.
[酸化安定化処理]
添着用樹脂と炭素粒子との混合物を添着した炭素繊維ペーパーは、空気中、温度150℃〜400℃、好ましくは200℃〜350℃、接圧0.1〜1.8MPa、好ましくは0.2〜1.0MPaで5〜300分、酸化安定化処理されて酸化シートになる。処理操作は、連続、バッチのいずれでも良い。
[Oxidation stabilization treatment]
The carbon fiber paper impregnated with a mixture of the resin to be attached and carbon particles has a temperature in air of 150 ° C. to 400 ° C., preferably 200 ° C. to 350 ° C., and a contact pressure of 0.1 to 1.8 MPa, preferably 0.2. Oxidation stabilization treatment is performed at ˜1.0 MPa for 5 to 300 minutes to form an oxidized sheet. The processing operation may be either continuous or batch.
[炭素化処理]
上記酸化シートを、バッチ操作又は連続操作で、窒素等の不活性ガス雰囲気下、500〜1200℃で予備焼成する工程を経由して1500〜2500℃で焼成して炭素化し、炭素繊維シートを得る。炭素化処理においてシートに掛かる接圧は、0.1〜1MPaであることが好ましい。
[Carbonization treatment]
The oxidized sheet is baked and carbonized at 1500 to 2500 ° C. through a step of pre-baking at 500 to 1200 ° C. in an inert gas atmosphere such as nitrogen in a batch operation or a continuous operation to obtain a carbon fiber sheet. . The contact pressure applied to the sheet in the carbonization treatment is preferably 0.1 to 1 MPa.
以下、実施例により本発明を更に具体的に説明するが、本発明はこれら実施例に限定されるものではない。なお、操作条件の評価、各物性の測定は前述又は以下の方法によった。 EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In addition, evaluation of operation conditions and measurement of each physical property were based on the above or the following methods.
[目付]
10cm角のシートを120℃、1hr乾燥した後の質量値より算出した。
[Unit weight]
The 10 cm square sheet was calculated from the mass value after drying at 120 ° C. for 1 hr.
[厚さ]
直径5mmφの円形圧板で厚さ方向に1.2Nの荷重(61.9kPa)を負荷したときの厚さを測定した。
[thickness]
The thickness when a load of 1.2 N (61.9 kPa) was applied in the thickness direction with a circular pressure plate having a diameter of 5 mmφ was measured.
[曲げ強度:3点曲げ試験法にて実施]
JIS K 6911に基づき、試験片サイズ:10mm幅×50mm長、試験速度1mm/min、圧子半径3.2mm、支点半径3.2mm、支点間距離16mmにて測定した値から求めた。
[Bending strength: Conducted by 3-point bending test method]
Based on JIS K 6911, the test piece size was determined from values measured at a width of 10 mm × 50 mm, a test speed of 1 mm / min, an indenter radius of 3.2 mm, a fulcrum radius of 3.2 mm, and a distance between fulcrums of 16 mm.
[曲げ撓み]
曲げ強度測定時の破断時の撓み量として求めた。
[Bending deflection]
It calculated | required as bending amount at the time of a fracture | rupture at the time of a bending strength measurement.
[曲げ弾性率]
曲げ強度測定時の撓み量が0.2mmから0.4mmの間の弾性率として求めた。
[Bending elastic modulus]
The amount of bending at the time of measuring the bending strength was determined as an elastic modulus between 0.2 mm and 0.4 mm.
[電気面積抵抗値]
2枚の50mm角(厚さ10mm)の金メッキした電極で、炭素繊維シートを電極が全面接触するように挟み、荷重10kPaをシートの厚さ方向に掛けたときの厚さ方向の電気面積抵抗値を測定した。
[Electric sheet resistance]
Two sheet of 50mm square (thickness 10mm) gold-plated electrodes, sandwiching the carbon fiber sheet so that the electrode is in full contact with each other, and applying a load of 10kPa in the thickness direction of the sheet in the thickness direction Was measured.
[電池特性]
炭素繊維シートを50cm角にカットし、これに触媒(Pt−Rt)を0.2mg/cm2担持させた。高分子電解質膜(ナフィオン117)の両面に上記触媒を担持させた炭素繊維シートを接合してセルを構成した。温度80℃で電流密度0.6/cm2でのセル電圧を測定し性能(電池特性)とした。
[Battery characteristics]
The carbon fiber sheet was cut into a 50 cm square, and 0.2 mg / cm 2 of catalyst (Pt-Rt) was supported on the carbon fiber sheet. A cell was constructed by bonding carbon fiber sheets carrying the catalyst on both sides of a polymer electrolyte membrane (Nafion 117). The cell voltage was measured at a temperature of 80 ° C. and a current density of 0.6 / cm 2 to obtain performance (battery characteristics).
[実施例1〜8、比較例1〜6]
表1〜4に示す条件で炭素繊維シートを作製し、上記の物性を測定した。その結果を表1〜4に示す。
[Examples 1-8, Comparative Examples 1-6]
Carbon fiber sheets were produced under the conditions shown in Tables 1 to 4, and the above physical properties were measured. The results are shown in Tables 1-4.
表1〜4に示すように、実施例1〜8においては良好な物性の炭素繊維シートが得られた。しかし、比較例1においては、原料炭素繊維ペーパーの樹脂付着量に対して炭素粒子含有量が少ないため、得られた炭素繊維シートは質量比[C/(B+C)]が小さく、曲げ撓み量が不足し、良好な物性のものではなかった。 As shown in Tables 1 to 4, carbon fiber sheets with good physical properties were obtained in Examples 1 to 8. However, in Comparative Example 1, since the carbon particle content is small relative to the resin adhesion amount of the raw carbon fiber paper, the obtained carbon fiber sheet has a small mass ratio [C / (B + C)], and the bending deflection amount is small. Insufficient and did not have good physical properties.
比較例2においては、原料炭素繊維ペーパーの樹脂付着量及び炭素粒子含有量が少ないため、得られた炭素繊維シートは質量比[(B+C)/A]が小さく、曲げ撓み量が不足し、良好な物性のものではなかった。 In Comparative Example 2, since the carbon adhering amount and the carbon particle content of the raw carbon fiber paper are small, the obtained carbon fiber sheet has a small mass ratio [(B + C) / A], and the bending deflection amount is insufficient. It was not a physical property.
比較例3においては、原料炭素繊維ペーパーの樹脂付着量及び炭素粒子含有量が多いため、得られた炭素繊維シートは質量比[(B+C)/A]が大きく、曲げ撓み量が不足し、良好な物性のものではなかった。 In Comparative Example 3, since the carbon adhering amount and the carbon particle content of the raw carbon fiber paper are large, the obtained carbon fiber sheet has a large mass ratio [(B + C) / A], and the bending deflection amount is insufficient. It was not a physical property.
比較例4においては、原料炭素繊維ペーパーに添着させる樹脂中に炭素粒子が含まれていないため、得られた炭素繊維シートは質量比[(B+C)/A]も質量比[C/(B+C)]も小さく、曲げ撓み量が不足し、良好な物性のものではなかった。 In Comparative Example 4, since carbon particles are not contained in the resin to be attached to the raw carbon fiber paper, the obtained carbon fiber sheet has a mass ratio [(B + C) / A] and a mass ratio [C / (B + C). ] Was also small, the amount of bending deflection was insufficient, and the physical properties were not good.
比較例5においては、酸化安定化処理をせずに炭素化処理しているため、原料炭素繊維ペーパーに添着させた樹脂由来の無定形炭素含有量(B)が減少した。その結果、得られた炭素繊維シートは質量比[C/(B+C)]が大きく、曲げ撓み量が不足し、良好な物性のものではなかった。 In Comparative Example 5, since the carbonization treatment was performed without the oxidation stabilization treatment, the amorphous carbon content (B) derived from the resin attached to the raw carbon fiber paper decreased. As a result, the obtained carbon fiber sheet had a large mass ratio [C / (B + C)], the bending deflection amount was insufficient, and the physical properties were not good.
比較例6においては、添着用樹脂に酸化安定化処理前の質量に対する炭素化処理後の質量で示される収率が高いフェノール樹脂を用い、原料炭素繊維ペーパーの樹脂付着量に対して炭素粒子含有量が少ないため、得られた炭素繊維シートは質量比[C/(B+C)]が小さく、曲げ撓み量が不足し、弾性率が高くなりすぎ、良好な物性のものではなかった。 In Comparative Example 6, a phenol resin having a high yield indicated by the mass after the carbonization treatment with respect to the mass before the oxidation stabilization treatment is used for the resin to be attached, and the carbon particles are contained with respect to the resin adhesion amount of the raw carbon fiber paper. Since the amount was small, the obtained carbon fiber sheet had a small mass ratio [C / (B + C)], the bending deflection amount was insufficient, the elastic modulus was too high, and the physical properties were not good.
2 炭素繊維シート
4 炭素繊維
6 炭素粒子
8 無定形炭素
10 無定形炭素又は炭素粒子の間で形成される間隙
2
Claims (4)
The carbon fiber sheet for a polymer electrolyte fuel cell gas diffusion layer according to claim 1, wherein the carbon particles are graphite particles or carbon black.
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