JP2004238791A - Fine carbon fiber - Google Patents
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本発明は特異な構造を持つ微細炭素繊維に関し、特に樹脂、ゴム等複合材のフィラー、半導体材料、触媒、あるいは電界電子放出材料として適した微細炭素繊維に関する。 The present invention relates to a fine carbon fiber having a unique structure, and more particularly to a fine carbon fiber suitable as a filler of a composite material such as resin and rubber, a semiconductor material, a catalyst, or a field electron emission material.
炭素繊維は、その高強度、高弾性率、高導電性等の優れた特性から各種の複合材料に使用されている。従来から応用されてきた優れた機械的特性ばかりでなく、炭素繊維あるいは炭素材料に備わった導電性を生かし、近年のエレクトロニクス技術の発展に伴い、電磁波シールド材、静電防止材用の導電性樹脂フィラーとして、あるいは樹脂への静電塗装のためのフィラーとしての用途が期待されてきている。また、炭素材料としての化学的安定性、熱的安定性と微細構造との特徴を生かし、フラットディスプレー等の電界電子放出材料としての用途が期待されている。 Carbon fibers are used in various composite materials because of their excellent properties such as high strength, high elastic modulus, and high conductivity. Utilizing not only the excellent mechanical properties that have been applied in the past, but also the conductive properties of carbon fiber or carbon materials, with the development of electronics technology in recent years, conductive resins for electromagnetic wave shielding and antistatic materials have been developed. It is expected to be used as a filler or as a filler for electrostatic coating on a resin. In addition, it is expected to be used as a field electron emission material such as a flat display by utilizing the characteristics of chemical stability, thermal stability and microstructure as a carbon material.
従来の炭素繊維は、ＰＡＮ、ピッチ、セルロース等の繊維を熱処理し炭化することにより製造するいわゆる有機系カーボンファイバーとして生産されている。これらを繊維強化複合材のフィラーとして用いる場合、母材との接触面積を大きくするために、径を細くすること、長さを長くすること等が補強効果を上げるために望ましい。また、母材との接着性を改善するためには、炭素繊維の表面が滑らかでなく、ある程度荒れている方が好ましく、このために空気中で高温に晒し酸化させたり、表面にコーティングを施こしたり等の表面処理が行なわれている。 Conventional carbon fibers are produced as so-called organic carbon fibers produced by heat-treating and carbonizing fibers such as PAN, pitch, and cellulose. When these are used as fillers of the fiber-reinforced composite material, it is desirable to increase the contact area with the base material by reducing the diameter or increasing the length in order to enhance the reinforcing effect. In order to improve the adhesiveness with the base material, it is preferable that the surface of the carbon fiber is not smooth but rough to some extent. For this reason, the carbon fiber is exposed to a high temperature in the air to be oxidized, or the surface is coated. Surface treatment such as rubbing is performed.
しかし、これらの炭素繊維は、その原料となる有機繊維の糸径が５〜１０μｍ程度であり、径の小さい、炭素繊維の製造は不可能であった。また、径に対する長さの比（アスペクト比）に限界があり、細くてアスペクト比の大きい炭素繊維が要望されていた。 However, in these carbon fibers, the organic fiber as a raw material has a yarn diameter of about 5 to 10 μm, and it is impossible to produce a carbon fiber having a small diameter. Further, there is a limit to the ratio of length to diameter (aspect ratio), and there has been a demand for thin carbon fibers having a large aspect ratio.
また、自動車ボディーへの樹脂の使用、あるいは電子機器への樹脂・ゴム等の使用に関しては、金属並の導電性を要求され、これに伴い、フィラー材としての炭素繊維もこれら各種導電性塗料、導電性樹脂などの要求を満たすために導電性を上げる必要が出てきた。
そのための手段として、黒鉛化することでこれら特性を向上させる必要があり、このために更に高温での黒鉛化処理が行なわれるのが通例である。しかし、この黒鉛化処理によっても金属並の導電性は得られず、これを補うために配合量を多くすると加工性や機械的特性が低下するという問題が生じ、繊維自体の更なる導電性の改良、繊維の細径化による強度の向上等が必要とされてきた。
また、電界電子放出材料としては、従来スピント法による電界電子放出が研究開発されてきたが、その製法には多くの工程が必要であり、かつ、従来電子放出部にはＭｏ等を用いて先端を針状に加工して用いているが、ディスプレーの電子放出材料として用いた場合には、化学的、熱的に不十分であった。
In addition, regarding the use of resins for automobile bodies or the use of resins and rubbers for electronic devices, conductivity similar to that of metal is required, and accordingly, carbon fibers as filler materials are also used for these various conductive paints, It has become necessary to increase conductivity in order to satisfy the requirements for conductive resins and the like.
As a means for achieving this, it is necessary to improve these properties by graphitization, and for this purpose, a graphitization treatment at a higher temperature is usually performed. However, even this graphitization does not provide the same level of conductivity as metals, and if the blending amount is increased to compensate for this, there arises a problem that workability and mechanical properties are reduced, and further conductivity of the fibers themselves is caused. There has been a need for improvement, improvement in strength by reducing the fiber diameter, and the like.
As a field electron emission material, field emission by the Spindt method has been conventionally researched and developed. However, the manufacturing method requires many steps, and a conventional electron emission portion is formed using Mo or the like. Was processed into a needle shape, but when used as an electron emission material for a display, it was insufficient chemically and thermally.
その後、１９８０年代後半に、これら有機系繊維と製法を全く異にするものとして、気相法炭素繊維（Ｖａｐｏｒ Ｇｒｏｗｎ Ｃａｒｂｏｎ Ｆｉｂｅｒ；以下ＶＧＣＦと略す。）が研究されるようになった。
このＶＧＣＦは、炭化水素等のガスを有機遷移金属系触媒の存在下で気相熱分解することによって直径１μｍ以下、数１００nmまでの炭素繊維が得られることが知られている。
たとえば、ベンゼン等の有機化合物を原料とし、触媒としてのフェロセン等の有機遷移金属化合物をキャリアーガスとともに高温の反応炉に導入し、基盤上に生成させる方法（特許文献１）、浮遊状態でＶＧＣＦを生成させる方法（特許文献２）、あるいは反応炉壁に成長させる方法（特許文献３）等が開示されている。
Then, in the late 1980's, vapor-grown carbon fiber (hereinafter, abbreviated as VGCF) began to be studied as a completely different production method from these organic fibers.
It is known that VGCF is obtained by subjecting a gas such as hydrocarbon to gas phase pyrolysis in the presence of an organic transition metal catalyst to obtain carbon fibers having a diameter of 1 μm or less and up to several 100 nm.
For example, a method in which an organic compound such as benzene is used as a raw material, an organic transition metal compound such as ferrocene as a catalyst is introduced into a high-temperature reactor together with a carrier gas, and is generated on a substrate (Patent Document 1). There is disclosed a method of generating the film (Patent Document 2), a method of growing the film on the reactor wall (Patent Document 3), and the like.
これら製法によれば、比較的細くて導電性に優れ、アスペクト比の大きいフィラー材に適した炭素繊維が得られるようになり、１００〜２００nm程度の径で、アスペクト比１０〜５００程度のものが量産化され、導電性フィラー材として樹脂用フィラーや鉛蓄電池の添加材等に使用されるようになった。 According to these manufacturing methods, carbon fibers suitable for a filler material having a relatively small thickness and excellent conductivity and having a large aspect ratio can be obtained, and those having a diameter of about 100 to 200 nm and an aspect ratio of about 10 to 500 can be obtained. It has been mass-produced and has been used as a conductive filler material as a filler for resins and as an additive for lead-acid batteries.
これらＶＧＣＦは、形状や結晶構造に特徴があり、炭素六角網面の結晶が年輪状に円筒形に巻かれ積層した構造を示し、その中心部には極めて細い中空部を有する繊維である。
しかし、これらＶＧＣＦについては、量産規模では１００nm未満の更に細い径のものは製造できなかった。
These VGCFs are characterized by their shape and crystal structure, and have a structure in which hexagonal carbon crystals are rolled into a cylindrical shape in a ring shape and stacked in a ring shape, and have a very thin hollow portion at the center.
However, with regard to these VGCFs, those having a smaller diameter of less than 100 nm could not be produced on a mass production scale.
また、このＶＧＣＦよりも更に細い炭素繊維として、飯島らによりヘリウムガス中でアーク放電により炭素電極を蒸発させた煤の中から、多層カーボンナノチューブが発見された。この多層カーボンナノチューブの直径は、１nm〜３０nmであり、ＶＧＣＦと同様に炭素六角網面の結晶が繊維の軸を中心に年輪状に幾重にも重なり円筒状に閉じられており、その中心部に中空径を有する微細炭素繊維である。 Further, as carbon fibers finer than the VGCF, multi-walled carbon nanotubes were discovered from soot obtained by evaporating a carbon electrode by arc discharge in helium gas by Iijima et al. The diameter of this multi-walled carbon nanotube is 1 nm to 30 nm, and like the VGCF, the crystals of the carbon hexagonal mesh plane are stacked in a ring shape around the axis of the fiber in multiple layers and closed in a cylindrical shape. It is a fine carbon fiber having a hollow diameter.
このアーク放電を使用する方法については、その製法から量産には向かず実用化には至っていない。 The method using this arc discharge is not suitable for mass production due to its production method and has not been put to practical use.
一方、気相法によるものは大きなアスペクト比、高導電性の可能性があり、この方法を改良し、より細い炭素繊維を製造しようとする試みがなされている。特許文献４，５では、約３．５〜７０nmの径でアスペクト比１００以上の黒鉛質からなる円柱状の炭素フィブリルが開示されている。その構造は、規則的に配列した炭素原子の連続層が多層にわたり円柱軸に対し同心的に配列され、炭素原子の各層のＣ軸がフィブリルの円柱軸に実質的に直交しており、全体に熱分解により析出する熱炭素被膜を含まず、滑らかな表面を持っているものである。 On the other hand, the vapor phase method has a large aspect ratio and a high conductivity, and attempts have been made to improve this method to produce finer carbon fibers. Patent Documents 4 and 5 disclose columnar carbon fibrils made of graphite having a diameter of about 3.5 to 70 nm and an aspect ratio of 100 or more. The structure is such that a continuous layer of regularly arranged carbon atoms is arranged concentrically with respect to the cylinder axis over multiple layers, the C axis of each layer of carbon atoms is substantially orthogonal to the cylinder axis of the fibrils, and It does not include a thermal carbon film deposited by thermal decomposition and has a smooth surface.
同様に、特許文献６には、１０〜５００nmでアスペクト比２〜３００００の気相法による炭素繊維が紹介されており、熱分解炭素層の厚みが直径の２０％以下であることが記されている。 Similarly, Patent Document 6 introduces a carbon fiber produced by a gas phase method having an aspect ratio of 2 to 30,000 at 10 to 500 nm, and describes that the thickness of the pyrolytic carbon layer is 20% or less of the diameter. I have.
上述のこれらの炭素繊維は、いずれも表面が滑らかなため接着性、濡れ性、親和性に乏しく、複合材料として用いる場合には表面を十分酸化処理する等の表面処理が必要になってくる。また、電界電子放出材料として用いる場合には、先端を細くする必要がある。 All of these carbon fibers have a smooth surface and thus poor adhesion, wettability, and affinity. When used as a composite material, a surface treatment such as a sufficient oxidation treatment of the surface is required. When used as a field electron emission material, it is necessary to make the tip thin.
本発明においては、導電性の良い４００nm未満、特に２〜３００nmのフィラー材として樹脂等への接着性の良い微細な炭素繊維を量産規模で得ること、また、化学的及び熱的に安定で電子の放出特性に優れ、寿命の長い電界電子放出材料を得ることが目的である。 In the present invention, a fine carbon fiber having good adhesion to a resin or the like is obtained on a mass production scale as a filler material having good conductivity of less than 400 nm, particularly 2 to 300 nm. It is an object of the present invention to obtain a field emission material having excellent emission characteristics and a long life.
本発明者らは、従来からのＶＧＣＦの製法を発展させ、従来とは違った構造を持つ新しい微細炭素繊維及びその製造方法を完成した。すなわち
（１）気相法で生成した微細炭素繊維を熱処理して黒鉛化して成る微細炭素繊維であって、円筒状の炭素シートが重なり合い多層構造をなし、その中心軸が中空構造であり、外径２〜３００nm、アスペクト比１０〜１５０００である微細炭素繊維であって、該炭素繊維の先端部において少なくとも１層の円筒状炭素シートが前記多層間で折り返して別の円筒状炭素シートと連続して、その折り返して連続する円筒状炭素シートが先端部で開いている円筒構造を形成していることを特徴とする微細炭素繊維。
（２）折り返して連続する円筒状炭素シートが、多層構造の外周部に存在することを特徴とする（１）に記載の微細炭素繊維。
（３）折り返して連続する円筒状炭素シートが形成する円筒構造の内側に、先端部が閉じている円筒状炭素シートが存在することを特徴とする（２）に記載の微細炭素繊維。
（４）先端部が閉じた円筒状炭素シートの内側にさらに、先端部で折り返して連続し合い炭素繊維の先端部で開いた円筒状を成す円筒状炭素シートが存在することを特徴とする（３）に記載の微細炭素繊維。
（５）外径２〜３００nm、アスペクト比１０〜１５０００の微細炭素繊維中に、（１）〜（４）に記載の微細炭素繊維が５質量％以上を占めることを特徴とする微細炭素繊維。
（６）外径２〜３００nm、アスペクト比１０〜１５０００の微細炭素繊維中に、微細炭素繊維が、５〜９０質量％を占めることを特徴とする（５）に記載の微細炭素繊維。
（７）外径２〜３００nm、アスペクト比１０〜１５０００の微細炭素繊維中に、透過型電子顕微鏡にて観察される（１）〜（６）記載の微細炭素繊維が、３〜８０体積％を占めることを特徴とする微細炭素繊維。
（８）微細炭素繊維が気相法炭素繊維であることを特徴とする（１）〜（７）記載の微細炭素繊維。
（９）ホウ素元素が炭素繊維に含まれたことを特徴とする（１）〜（８）に記載の微細炭素繊維。
（１０）ホウ素元素が炭素繊維の炭素元素と一部置換したことを特徴とする（１）〜（９）に記載の微細炭素繊維。
（１１）筒状の炭素シートが重なり合い多層構造をなし、その中心軸が中空構造である外径２〜３００nm、アスペクト比１０〜１５０００の微細炭素繊維を熱処理することにより（１）〜（１０）に記載の微細炭素繊維を製造する方法。
（１２）熱処理温度が２０００℃〜３５００℃であることを特徴とする（１１）に記載の微細炭素繊維の製造方法。
（１３）筒状の炭素シートが重なり合い多層構造をなし、その中心軸が中空構造である外径２〜３００nm、アスペクト比１０〜１５０００の微細炭素繊維とホウ素化合物とを混合して熱処理することを特徴とする（１１）または（１２）に記載の微細炭素繊維の製造方法。
The present inventors have developed a conventional method for producing VGCF, and have completed a new fine carbon fiber having a structure different from the conventional one and a method for producing the same. That is, (1) fine carbon fibers formed by heat treatment and graphitization of fine carbon fibers produced by a vapor phase method, wherein a cylindrical carbon sheet is overlapped to form a multilayer structure, the central axis of which is a hollow structure, A fine carbon fiber having a diameter of 2 to 300 nm and an aspect ratio of 10 to 15000, wherein at least one layer of a cylindrical carbon sheet is folded between the multilayers at the tip of the carbon fiber to be continuous with another cylindrical carbon sheet. A fine carbon fiber characterized in that the folded and continuous cylindrical carbon sheet forms a cylindrical structure open at the tip.
(2) The fine carbon fiber according to (1), wherein the folded and continuous cylindrical carbon sheet is present on the outer peripheral portion of the multilayer structure.
(3) The fine carbon fiber according to (2), wherein a cylindrical carbon sheet having a closed end is present inside a cylindrical structure formed by folding and forming a continuous cylindrical carbon sheet.
(4) Inside the cylindrical carbon sheet having a closed distal end, there is a cylindrical carbon sheet that is folded back at the distal end and continues to form a cylindrical shape opened at the distal end of the carbon fiber. Fine carbon fibers according to 3).
(5) A fine carbon fiber characterized in that the fine carbon fiber according to (1) to (4) accounts for 5% by mass or more of the fine carbon fiber having an outer diameter of 2 to 300 nm and an aspect ratio of 10 to 15000.
(6) The fine carbon fiber according to (5), wherein the fine carbon fiber accounts for 5 to 90% by mass of the fine carbon fiber having an outer diameter of 2 to 300 nm and an aspect ratio of 10 to 15000.
(7) The fine carbon fibers according to (1) to (6), which are observed with a transmission electron microscope in a fine carbon fiber having an outer diameter of 2 to 300 nm and an aspect ratio of 10 to 15,000, contain 3 to 80% by volume. Fine carbon fiber characterized by occupying.
(8) The fine carbon fiber according to any one of (1) to (7), wherein the fine carbon fiber is a vapor grown carbon fiber.
(9) The fine carbon fiber according to any one of (1) to (8), wherein the boron element is contained in the carbon fiber.
(10) The fine carbon fiber according to any one of (1) to (9), wherein the boron element is partially substituted for the carbon element of the carbon fiber.
(11) A heat treatment is performed on fine carbon fibers having an outer diameter of 2 to 300 nm and an aspect ratio of 10 to 15000, each of which has a multilayer structure in which a cylindrical carbon sheet is overlapped and has a hollow central axis, and (1) to (10). A method for producing a fine carbon fiber according to the above.
(12) The method for producing fine carbon fibers according to (11), wherein the heat treatment temperature is 2000 ° C to 3500 ° C.
(13) Heat treatment by mixing a carbon compound with a fine carbon fiber having an outer diameter of 2 to 300 nm and an aspect ratio of 10 to 15000 and a boron compound, wherein a cylindrical carbon sheet overlaps to form a multilayer structure, and the central axis of which is a hollow structure. The method for producing fine carbon fibers according to (11) or (12), wherein
本発明によれば、従来の炭素繊維や気相法炭素繊維と異なり、外径が２〜３００nmであり、そのアスペクト比が１０〜１５０００で、該炭素繊維の先端部において少なくとも１層の円筒状炭素シートが前記多層間で折り返して別の円筒状炭素シートと連続して、その折り返して連続する円筒状炭素シートが先端部で開いている円筒を形成していることを特徴とする微細炭素繊維を提供でき、電界電子放出、気体の吸蔵、樹脂用導電性フィラーとして有用である。 According to the present invention, unlike conventional carbon fibers and vapor grown carbon fibers, the outer diameter is 2 to 300 nm, the aspect ratio is 10 to 15000, and at least one layer of cylindrical shape is formed at the tip of the carbon fiber. Fine carbon fibers characterized in that the carbon sheet is folded between the multilayers and is continuous with another cylindrical carbon sheet, and the folded and continuous cylindrical carbon sheet forms a cylinder open at the tip end And is useful as a field electron emission, gas occlusion, and conductive filler for resin.
以下、本発明について詳細に説明する。
本発明は、導電性の良い、外径４００nm未満、特に２〜３００nm、さらには１〜８０nmのフィラー材として樹脂等への接着性の良い、微細な炭素繊維を得るために、検討を進める中で、微細なＶＧＣＦをホウ素化合物の存在下で高温熱処理して黒鉛化を図っていたとき、従来知られていない形態の微細な炭素繊維が得られ、これが導電性が高く、また樹脂等への接着性にも優れており、さらには化学的及び熱的に安定で電子の放出特性に優れ、寿命の長い電界電子放出材料を与えること、またこの新規な形態の微細炭素繊維は熱処理もホウ素化合物の存在下に限らず得られうるものであることを見出したものである。本発明の微細炭素繊維は基本的により微細でかつより黒鉛化度の高い炭素繊維を製造しようとする過程に得られる１形態の炭素繊維であると理解される。
本発明の微細炭素繊維について説明する。
本発明の微細炭素繊維の特徴を添付図面（図１〜４）を用いて説明する。これらの図において、模式的に炭素シート（黒鉛または黒鉛に近い結晶の層）を実線で表す。
先ず従来の１００nm未満、アスペクト比１０〜１５０００の微細炭素繊維は、図１の模式断面図に示すように、円筒状の炭素シートが重なり合い多層構造（年輪構造）をなし、その中心軸が中空構造であるものが知られているが、そのような公知の微細炭素繊維は繊維の先端部では多層構造を構成する円筒状炭素シートは全てがある曲率をもって閉じている。これに対して、本発明の微細炭素繊維は下記の如き構造を有する。
１）図２、図４に示す如く、円筒状の炭素シートが重なり合い多層構造をなし、その中心軸が中空構造であり、外径２〜３００nm、アスペクト比１０〜１５０００である微細炭素繊維１０において、該炭素繊維の先端部において少なくとも１層の円筒状炭素シート１４（１４ａ，１４ｂ）が前記多層間で折り返して別の円筒状炭素シート１５（１５ａ，１５ｂ）と連続して、その折り返して連続する円筒状炭素シート１４、１５が構成する円筒は炭素繊維の先端部で開いていることを特徴とする微細炭素繊維。従来の微細な炭素繊維を酸化すると繊維の先端が強制的に破壊されることがある（米国特許第５，６４１，４６６号明細書）が、その場合には黒鉛形成条件ではないので炭素シートが折り返して連続することはない。
２）図２を参照すると、上記１）の微細炭素繊維において、前記折り返して連続する円筒状炭素シート１４，１５が、多層構造の外周部に存在することを特徴とする微細炭素繊維。折り返して連続する炭素シートは一般的に多層構造の外周部に形成され易い。
３）図２を参照すると、上記２）の微細炭素繊維において、前記折り返して連続する円筒状炭素シート１４、１５が形成する円筒の内側に、先端部１２Ａが閉じている円筒状炭素シート１３（１３ａ，１３ｂ）が存在することを特徴とする微細炭素繊維。一般的に、折り返して連続する炭素シートが構成する円筒は多層構造の外周部に存在する傾向があるが、その内側にはさらに円筒状炭素シートが存在し、その先端部１２Ａは閉じていることが多い。
４）図３を参照すると、上記３）の微細炭素繊維において、前記先端部が閉じた円筒状炭素シート１３の内側にさらに、先端部で折り返して連続し合い炭素繊維の先端部で開いた円筒状を成す円筒状炭素シート１１，１２が存在することを特徴とする微細炭素繊維。
５）図４を参照すると、微細炭素繊維は折り返して連続する炭素シートが構成する円筒だけからなり、炭素繊維の先端は開いている形態のものも得られうる。図４の場合に限らず、微細炭素繊維は折り返して連続する炭素シート１４，１５が構成する円筒において、その内部のどこかに折り返していない炭素シート１６が存在してもよい。
６）外径２〜３００nm、アスペクト比１０〜１５０００の微細炭素繊維中に、上記１）〜５）いずれか記載の微細炭素繊維が５質量％以上を占める微細炭素繊維。
以上、本発明の微細炭素繊維の代表的な形態を説明したが、本発明の微細炭素繊維は、炭素繊維の先端部において少なくとも１層の円筒状炭素シートが多層間で折り返して別の円筒状炭素シートと連続して、その折り返して連続する円筒状炭素シートが構成する円筒は炭素繊維の先端部で開いていることを特徴とするものであり、その他の変化は任意である。例えば、炭素繊維の先端部において多層間で折り返して別の円筒状炭素シートと連続する円筒状炭素シートの層数は、少なくとも１層であればよく、２層あるいは３層以上の隣接した円筒状炭素シートが折り返して別の円筒状炭素シートと連続していてもよい。また、折り返して連続する円筒状炭素シートどうしは隣接していても隣接していなくてもよい。例えば、図４では、円筒状炭素シート１４と円筒状炭素シート１５が折り返して連続するが、円筒状炭素シート１４と円筒状炭素シート１５とは間に円筒状炭素シート１６が介在して相互に隣接していない。
また、炭素シートによって構成される炭素繊維の先端部や周囲に不定形炭素が存在しても、本発明の微細炭素繊維は影響されない。
Hereinafter, the present invention will be described in detail.
The present invention is being studied in order to obtain fine carbon fibers having good conductivity, an outer diameter of less than 400 nm, particularly 2 to 300 nm, and further having a good adhesion to a resin or the like as a filler material of 1 to 80 nm. When fine VGCF is subjected to high-temperature heat treatment in the presence of a boron compound to graphitize, fine carbon fibers in a conventionally unknown form are obtained, which has high conductivity and is used for resin and the like. It has excellent adhesiveness, is chemically and thermally stable, has excellent electron emission characteristics, and provides a long-lived field electron emission material. Has been found to be obtainable not only in the presence of. It is understood that the fine carbon fiber of the present invention is basically one type of carbon fiber obtained in the process of producing a finer and higher graphitized carbon fiber.
The fine carbon fiber of the present invention will be described.
The characteristics of the fine carbon fiber of the present invention will be described with reference to the attached drawings (FIGS. 1 to 4). In these figures, a carbon sheet (a layer of graphite or a crystal close to graphite) is schematically represented by a solid line.
First, as shown in the schematic cross-sectional view of FIG. 1, a conventional fine carbon fiber of less than 100 nm and an aspect ratio of 10 to 15,000 has a multilayer structure (annular ring structure) in which cylindrical carbon sheets are overlapped, and the central axis thereof is a hollow structure. However, in such a known fine carbon fiber, all the cylindrical carbon sheets constituting the multilayer structure are closed with a certain curvature at the tip of the fiber. On the other hand, the fine carbon fiber of the present invention has the following structure.
1) As shown in FIG. 2 and FIG. 4, in a fine carbon fiber 10 in which cylindrical carbon sheets overlap to form a multilayer structure, the central axis of which is a hollow structure, an outer diameter of 2 to 300 nm, and an aspect ratio of 10 to 15000. At least one layer of the cylindrical carbon sheet 14 (14a, 14b) at the tip of the carbon fiber is folded between the layers to be continuous with another cylindrical carbon sheet 15 (15a, 15b), and then folded back to be continuous. The fine carbon fiber is characterized in that the cylinder formed by the cylindrical carbon sheets 14 and 15 is open at the tip of the carbon fiber. When the conventional fine carbon fiber is oxidized, the tip of the fiber may be forcibly broken (U.S. Pat. No. 5,641,466). In this case, however, the carbon sheet is not formed under graphite forming conditions. It does not turn back and continue.
2) Referring to FIG. 2, the fine carbon fiber according to 1) above, wherein the folded and continuous cylindrical carbon sheets 14 and 15 are present on the outer peripheral portion of the multilayer structure. A folded and continuous carbon sheet is generally easily formed on the outer peripheral portion of the multilayer structure.
3) Referring to FIG. 2, in the fine carbon fiber of the above 2), the cylindrical carbon sheet 13 (the tip 12A of which is closed) inside the cylinder formed by the folded and continuous cylindrical carbon sheets 14 and 15 ( 13a, 13b). In general, a cylinder formed by a continuous carbon sheet that is folded back tends to be present on the outer peripheral portion of the multilayer structure. However, a cylindrical carbon sheet is further present on the inner side, and the tip portion 12A is closed. There are many.
4) Referring to FIG. 3, in the fine carbon fiber of the above 3), the cylindrical portion is further folded back at the front end inside the cylindrical carbon sheet 13 whose front end is closed and opened at the front end of the carbon fiber. A fine carbon fiber characterized by having cylindrical carbon sheets 11 and 12 in a shape.
5) Referring to FIG. 4, the fine carbon fiber is formed only of a cylinder formed by folding back and forming a continuous carbon sheet, and the carbon fiber may have an open end. The present invention is not limited to the case of FIG. 4, and the fine carbon fiber may be folded back and a carbon sheet 16 that is not folded may exist somewhere inside the cylinder formed by the continuous carbon sheets 14 and 15.
6) A fine carbon fiber in which the fine carbon fiber according to any one of the above 1) to 5) accounts for 5% by mass or more of the fine carbon fiber having an outer diameter of 2 to 300 nm and an aspect ratio of 10 to 15000.
As described above, the typical form of the fine carbon fiber of the present invention has been described. However, the fine carbon fiber of the present invention is formed by folding at least one layer of a cylindrical carbon sheet at the tip of the carbon fiber between the multiple layers and forming another cylindrical carbon sheet. The cylinder formed by the cylindrical carbon sheet that is continuous with the carbon sheet and that is folded back is characterized by being open at the tip of the carbon fiber, and other changes are optional. For example, the number of layers of the cylindrical carbon sheet that is folded between the multilayers at the tip of the carbon fiber and is continuous with another cylindrical carbon sheet may be at least one layer, and may be two or three or more adjacent cylindrical carbon sheets. The carbon sheet may be folded back to be continuous with another cylindrical carbon sheet. Further, the folded and continuous cylindrical carbon sheets may or may not be adjacent to each other. For example, in FIG. 4, the cylindrical carbon sheet 14 and the cylindrical carbon sheet 15 are folded back to be continuous, but the cylindrical carbon sheet 14 and the cylindrical carbon sheet 15 are mutually interposed with the cylindrical carbon sheet 16 interposed therebetween. Not adjacent.
In addition, even if amorphous carbon is present at or around the tip of the carbon fiber constituted by the carbon sheet, the fine carbon fiber of the present invention is not affected.
本発明の微細炭素繊維は、微細炭素の繊維部分の構造としては、炭素原子からなる筒状の炭素シートが重なり合った多層構造であり、中心軸には中空の空洞部分が存在する。これらの炭素シートは規則的に配列した炭素原子が連続したもの、あるいは繊維の長手直角方向からこれを観察すると、おおむね繊維方向に直線状に、多重に重なりあっているが、筒状のシートが長手方向にて途切れて不連続になっている部分があり、また、中心軸の中空部の内径が一定していなくとも良い。
本発明の微細炭素繊維の上記のような形態は、従来の各種気相法による炭素繊維では報告されておらず、新規なものである。
The fine carbon fiber of the present invention has a multilayer structure in which cylindrical carbon sheets made of carbon atoms overlap each other as the structure of the fine carbon fiber portion, and a hollow hollow portion exists at the central axis. When these carbon sheets are observed in the direction perpendicular to the longitudinal direction of the fiber, or when the carbon atoms arranged regularly are continuous, they are almost linearly overlapped in a line in the fiber direction. There is a portion that is interrupted and discontinuous in the longitudinal direction, and the inner diameter of the hollow portion of the central shaft may not be constant.
The above-mentioned form of the fine carbon fiber of the present invention has not been reported in conventional carbon fibers produced by various vapor phase methods and is novel.
これら本発明の微細炭素繊維は、先端に従来にない異なる特徴を持ち、従来の炭素繊維に対し更に先端が細くなった部分が存在し、先端が細い導電性物質の方が電子放出の方向性を持ち、印加電界を集中させることができ、電界電子放出特性が向上し、電界電子放出素子として適する。また、同様に先端部が異形をしているので導電性フィラー等として使用した場合、樹脂等への接着性が向上する効果がある。
また、本微細炭素繊維を５質量％以上さらに５〜９０質量％、好ましくは１０〜７０質量％、特に１０〜５０質量％を含むとその構造の特徴により、電界電子放出特性が向上し、また導電性フィラー等として使用した場合は、樹脂等への接着性が向上する効果がある。また、透過型電子顕微鏡による観察にて、微細炭素繊維の構造は確認できるが、本発明の微細炭素繊維を３〜８０体積％さらに、５〜７０体積％、好ましくは１０〜５０体積％含むと電界電子放出特性が向上し、また導電性フィラー等として使用した場合は、樹脂等への接着性などが向上する効果がある。
The fine carbon fiber of the present invention has a different feature at the tip than ever before, and there is a part with a tip that is even thinner than the conventional carbon fiber. , The concentration of the applied electric field can be concentrated, the field electron emission characteristics are improved, and the device is suitable as a field electron emission element. Similarly, since the tip portion is irregularly shaped, when used as a conductive filler or the like, there is an effect that the adhesiveness to a resin or the like is improved.
When the content of the present fine carbon fiber is 5% by mass or more, more preferably 5 to 90% by mass, preferably 10 to 70% by mass, and particularly preferably 10 to 50% by mass, the field emission characteristics are improved by the characteristics of its structure. When used as a conductive filler or the like, there is an effect that adhesion to a resin or the like is improved. Further, the structure of the fine carbon fiber can be confirmed by observation with a transmission electron microscope. However, when the fine carbon fiber of the present invention is contained in an amount of 3 to 80% by volume, further 5 to 70% by volume, preferably 10 to 50% by volume. Field electron emission characteristics are improved, and when used as a conductive filler or the like, there is an effect that adhesion to a resin or the like is improved.
本発明の微細炭素繊維は、外径が２〜３００nmで、アスペクト比１０〜１５０００の微細で長い繊維が得られるので、フィラー材として多量に添加が可能であり補強効果に優れるものである。 The fine carbon fiber of the present invention has an outer diameter of 2 to 300 nm, and a fine and long fiber having an aspect ratio of 10 to 15000 can be obtained. Therefore, it can be added in a large amount as a filler material and has an excellent reinforcing effect.
更に、上記の構造を有するものは炭素シートの端面が外部に出ていることから、電池の添加材として使用した場合に、イオンの補足性がよく、また導電性についても従来の気相法炭素繊維と変わらず、かつ表面が平滑でないため電池の電解液との濡れ性もよい。従って電池用の添加材として好適であるという特徴を有する。
本発明の特異な形態を有する微細な炭素繊維は、微細な炭素繊維であって黒鉛化の高いものを製造する方法であれば製造される可能性があるが、以下に本発明の微細な炭素繊維を製造するために好適な方法について説明する。
本発明の微細炭素繊維は、一般的には、遷移金属触媒を用いて有機化合物、特に炭化水素類を熱分解することにより粗微細炭素繊維を得、それを更に２０００〜３５００℃、好ましくは２５００〜３５００℃の熱処理を行うことにより得られる。微細炭素繊維が上記の折り返し構造をもつ理由は炭素シート間の距離が小さくなるためと考えられるので、できるだけ炭素シート間隔を小さくするような条件を採用することにより、本発明の微細炭素繊維はより容易に得られる。従って、粗微細炭素繊維を熱処理する際にホウ素化合物を存在させることが有利である。ホウ素化合物を共存させると、熱処理温度を無添加に比べ数百℃低くすることができ、また同じ熱処理温度では無添加に比べ繊維径に対する外周部分の比率を大きくすることができる。ホウ素化合物としては、加熱によりホウ素を生成する物質であればよく、例えば、炭化ホウ素、ホウ素酸化物、有機ホウ素酸化物等の固体、液体、さらには気体でもよい。
Further, since the carbon sheet having the above structure has an end face of the carbon sheet exposed to the outside, when used as an additive for a battery, it has a good ion-capturing property and also has a good conductivity with respect to a conventional vapor-phase carbon. Since it is the same as a fiber and has a non-smooth surface, it has good wettability with the battery electrolyte. Therefore, it has a feature that it is suitable as an additive for batteries.
The fine carbon fiber having a peculiar form of the present invention may be produced by a method for producing a fine carbon fiber having high graphitization. A preferred method for producing fibers will be described.
The fine carbon fiber of the present invention is generally obtained by thermally decomposing an organic compound, particularly a hydrocarbon, using a transition metal catalyst to obtain coarse and fine carbon fiber, which is further subjected to 2,000 to 3,500 ° C, preferably 2,500. It is obtained by performing a heat treatment at 〜3500 ° C. The reason why the fine carbon fibers have the above-mentioned folded structure is considered to be that the distance between the carbon sheets becomes small.Therefore, by adopting conditions that make the carbon sheet interval as small as possible, the fine carbon fibers of the present invention are more Obtained easily. Therefore, it is advantageous to include a boron compound when the coarse and fine carbon fibers are heat-treated. When a boron compound is present, the heat treatment temperature can be lowered by several hundred degrees centigrade as compared with the case where no boron compound is added, and the ratio of the outer peripheral portion to the fiber diameter can be increased at the same heat treatment temperature as compared with the case where no boron compound is added. The boron compound may be any substance that generates boron by heating, and may be, for example, a solid, liquid, or gas such as boron carbide, boron oxide, or organic boron oxide.
最初に遷移金属触媒を用いて有機化合物、特に炭化水素類を熱分解することにより粗微細炭素繊維を得る。
有機遷移金属化合物は、触媒となる遷移金属を含むものである。遷移金属としては、周期律表第IVａ，Ｖａ，VIａ，VIIａ，VIII族の金属を含む有機化合物である。中でもフェロセン、ニッケルセン等の化合物が好ましい。触媒としての有機遷移金属化合物の含有量としては、有機化合物の炭素量に対して０．０１〜１５．０質量％、好ましくは０．０３〜１０．０質量％、好ましくは０．１〜５．０質量％が良い。
またその他、助触媒として硫黄化合物を用いるが、その形態は特に制限は無く、炭素源である有機化合物に溶解するものなら良い。その硫黄化合物として、チオフェンや各種チオールあるいは、無機硫黄等が用いられる。その使用量は有機化合物に対して０．０１〜１０．０質量％、好ましくは、０．０３〜５．０質量％、さらに好ましくは０．１〜４．０質量％が良い。
First, coarse and fine carbon fibers are obtained by thermally decomposing organic compounds, particularly hydrocarbons, using a transition metal catalyst.
The organic transition metal compound contains a transition metal serving as a catalyst. The transition metal is an organic compound containing a metal belonging to Group IVa, Va, VIa, VIIa or VIII of the periodic table. Among them, compounds such as ferrocene and nickel sen are preferable. The content of the organic transition metal compound as a catalyst is 0.01 to 15.0% by mass, preferably 0.03 to 10.0% by mass, preferably 0.1 to 5% by mass based on the carbon amount of the organic compound. 0.0% by mass is good.
In addition, a sulfur compound is used as a cocatalyst, but the form is not particularly limited, and any form may be used as long as it can be dissolved in an organic compound as a carbon source. As the sulfur compound, thiophene, various thiols, inorganic sulfur, or the like is used. The amount used is 0.01 to 10.0% by mass, preferably 0.03 to 5.0% by mass, and more preferably 0.1 to 4.0% by mass, based on the organic compound.
炭素繊維の原料となる有機化合物は、ベンゼン、トルエン、キシレン、メタノール、エタノール、ナフタレン、フェナントレン、シクロプロパン、シクロペンテン、シクロヘキサン有機化合物や揮発油、灯油等あるいはＣＯ、天然ガス、メタン、エタン、エチレン、アセチレン等のガス及びそれらの混合物も可能である。中でもベンゼン、トルエン、キシレン等の芳香族化合物が特に好ましい。 Organic compounds used as raw materials for carbon fiber include benzene, toluene, xylene, methanol, ethanol, naphthalene, phenanthrene, cyclopropane, cyclopentene, cyclohexane organic compounds and volatile oils, kerosene, etc., CO, natural gas, methane, ethane, ethylene, Gases such as acetylene and mixtures thereof are also possible. Among them, aromatic compounds such as benzene, toluene and xylene are particularly preferred.
キャリヤーガスとしては、通常水素ガスをはじめとする還元性のガスが使用される。キャリヤーガスを予め５００〜１３００℃に加熱しておくことが好ましい。加熱する理由は、反応時に触媒の金属の生成と炭素化合物の熱分解による炭素源の供給を一致させ、反応を瞬時に起こすようにして、より微細な炭素繊維が得られるようにするためである。キャリアーガスを原料と混合した際に、キャリアーガスの加熱温度が５００℃未満では、原料の炭素化合物の熱分解が起こりにくく、１３００℃をこえると炭素繊維の径方向の成長が起こり、径が太くなりやすい。 As the carrier gas, a reducing gas such as a hydrogen gas is usually used. It is preferable that the carrier gas be heated to 500 to 1300 ° C. in advance. The reason for heating is to make the production of the metal of the catalyst and the supply of the carbon source by pyrolysis of the carbon compound coincide with each other during the reaction, so that the reaction is instantaneously performed and finer carbon fibers can be obtained. . When the carrier gas is mixed with the raw material, if the heating temperature of the carrier gas is less than 500 ° C., thermal decomposition of the carbon compound of the raw material is unlikely to occur, and if it exceeds 1300 ° C., the carbon fiber grows in the radial direction, and the diameter increases. Prone.
キャリアーガスの使用量は、炭素源である有機化合物１．０モル部に対し１〜７０モル部が適当である。炭素繊維の径は、炭素源とキャリアーガスの比率を変えることにより、制御することが出来る。
原料は、炭素源の有機化合物に遷移金属化合物及び助触媒の硫黄化合物を溶解し調整する。そして原料は液体のままキャリアーガスで噴霧して反応炉へ供給することも出来るが、キャリアーガスの一部をパージガスとして気化させて反応炉へ供給し反応させることも出来る。繊維径の細い炭素繊維を得る場合は原料は気化して反応炉へ供給した方が好ましい。
An appropriate amount of the carrier gas is 1 to 70 mol parts per 1.0 mol part of the organic compound as the carbon source. The diameter of the carbon fiber can be controlled by changing the ratio between the carbon source and the carrier gas.
The raw material is prepared by dissolving a transition metal compound and a co-catalyst sulfur compound in an organic compound as a carbon source. The raw material can be sprayed with a carrier gas in a liquid state and supplied to the reaction furnace. Alternatively, a part of the carrier gas can be vaporized as a purge gas and supplied to the reaction furnace for reaction. When obtaining a carbon fiber having a small fiber diameter, it is preferable that the raw material is vaporized and supplied to the reaction furnace.
反応炉は、通常縦型の電気炉を使用する。反応炉温度は８００〜１３００℃、好ましくは１０００〜１３００℃である。所定の温度に昇温した反応炉へ、原料液とキャリアーガスあるいは原料を気化させた原料ガスとキャリアーガスとを供給し、反応させ炭素繊維を得る。 As the reaction furnace, a vertical electric furnace is usually used. The reactor temperature is 800-1300 ° C, preferably 1000-1300 ° C. A raw material liquid and a carrier gas or a raw material gas obtained by evaporating a raw material and a carrier gas are supplied to a reaction furnace heated to a predetermined temperature, and reacted to obtain carbon fibers.
このようにして反応炉に吹き込まれたガスが熱分解し、有機化合物は炭素源となり、有機遷移金属化合物は触媒の遷移金属粒子となり、この遷移金属粒子を核とした微細炭素繊維の生成が行われる。
得られた微細炭素繊維は、さらに、ヘリウム、アルゴン等の不活性ガス雰囲気化で、９００〜１５００℃の熱処理を行い、更に２０００〜３５００℃の熱処理を行う、あるいは、反応により得られた状態の微細炭素繊維を不活性ガス雰囲気化、直接２０００〜３５００℃の熱処理を行って、本発明の特異な微細炭素繊維を得ることが可能である。
しかし、反応により得られた状態の微細炭素に、あるいはその微細炭素繊維を不活性ガス雰囲気下で９００〜１５００℃の熱処理を行った後に、炭化ホウ素（Ｂ4Ｃ）、酸化ホウ素（Ｂ2Ｏ3）、元素状ホウ素、ホウ酸（Ｈ3ＢＯ3）、ホウ酸塩等のホウ素化合物と混合して、更に不活性ガス雰囲気下２０００〜３５００℃で熱処理を行うことにより、本発明の特異な微細炭素繊維をより容易に得ることが可能である。ホウ素化合物の添加量は、用いるホウ素化合物の化学的特性、物理的特性に依存するために限定されないが、例えば炭化ホウ素（Ｂ4Ｃ）を使用した場合には、微細炭素繊維に対して０．０５〜１０質量％、好ましくは０．１〜５質量％の範囲が良い。
微細炭素繊維にホウ素が含まれるとは、ホウ素が一部固溶して、炭素繊維の表面、炭素六角網面の積層体層間、中空部内に存在したり、炭素原子とホウ素原子が一部置換した状態をいう。
The gas blown into the reactor in this way is thermally decomposed, the organic compound becomes a carbon source, the organic transition metal compound becomes transition metal particles of the catalyst, and fine carbon fibers are formed with the transition metal particles as nuclei. Is
The obtained fine carbon fiber is further subjected to a heat treatment at 900 to 1500 ° C. and further to a heat treatment at 2000 to 3500 ° C. in an atmosphere of an inert gas such as helium, argon, or the state obtained by the reaction. The unique fine carbon fiber of the present invention can be obtained by subjecting the fine carbon fiber to an inert gas atmosphere and directly performing heat treatment at 2000 to 3500 ° C.
However, after performing a heat treatment at 900 to 1500 ° C. on the fine carbon obtained by the reaction or the fine carbon fiber in an inert gas atmosphere, boron carbide (B 4 C), boron oxide (B 2 O) 3 ) By mixing with boron compounds such as elemental boron, boric acid (H 3 BO 3 ), and borate, and further performing a heat treatment at 2000 to 3500 ° C. in an inert gas atmosphere, Fine carbon fibers can be obtained more easily. The amount of the boron compound added is not limited because it depends on the chemical and physical properties of the boron compound used. For example, when boron carbide (B 4 C) is used, the amount of the boron compound is 0.1% based on the fine carbon fibers. The range is from 0.05 to 10% by mass, preferably from 0.1 to 5% by mass.
The fact that boron is contained in the fine carbon fiber means that boron is partially dissolved and exists in the surface of the carbon fiber, between the layers of the hexagonal carbon layer, in the hollow portion, or partially replaced by carbon atoms and boron atoms. The state which did.
以下、本発明の実施例をあげて説明する。
概略図の図５に示すように縦型加熱炉１（内径１７０mm、長さ１５００mm）の頂部に、原料気化器５を通して気化させた原料を供給する原料供給管４と、キャリアーガス供給配管６を取りつけた。
原料供給管４からは、フェロセン３質量％、チオフェン１質量％溶解したトルエンを気化させ２０ｇ／分で供給し、キャリアーガスとして水素を用い、７５リットル／分で供給し反応させた。この反応で得られた微細炭素繊維の透過型電子顕微鏡写真を図６に示す。
この反応で得られた微細炭素繊維をＡｒ（アルゴン）雰囲気下１３００℃で熱処理し、更に１３００℃処理品をＡｒ雰囲気下２８００℃で熱処理し重量回収率９６％で微細炭素繊維を得た。
また、この微細炭素繊維のＡｒ雰囲気下１３００℃熱処理品に対してＢ4Ｃを４質量％混合してＡｒ雰囲気下２８００℃で熱処理し重量回収率９４％で微細炭素繊維を得た。この透過型電子顕微鏡写真を図７に示す。
図６、図７ともに、炭素原子からなる筒状の炭素シートが重なりあった多層構造であり、その中心軸が中空構造である。しかし、図６では図１の模式図に対応し、先端が閉じているが、図７ではおおよそ図３の模式図に対応する形態を有する多層構造が見られる。
即ち、図７では、その先端が開いた円筒を形成している外周部（図３の１４，１５に対応）と、先端が閉じた中間部（図３の１３に対応）と、さらにその内側に先端が開いた円筒（図３の１１，１２に対応）を有する。また、多層構造の外側と内側を構成するそれぞれの炭素シート（図３の１４，１５と１１，１２に対応）の末端がお互いに折り返して結合して連続している。多層構造の外側と内側の折り返した炭素シートの層の中間をなす炭素シート（図３の１３に対応）は、先端（図３の１２Ａに対応）が閉じている。なお、図７では、炭素繊維の先端部において繊維の断面方向に炭素シートが見えるが、この炭素シートは外周部の炭素シートの折り返し部分が炭素シートとして見えているものであり、繊維の軸心部に炭素シートが存在するわけではない。また、同様に、炭素繊維の先端部において、中間部炭素シートの閉じた先端部の炭素シートの先が空洞でなく何か物質が存在するように見えるが、この部分は不定形炭素が付着しているものであり、炭素繊維の構造には関係ないものである。不定形炭素は炭素繊維の円周部表面にも存在するのが見られる。
Hereinafter, an example of the present invention will be described.
As shown in FIG. 5 of the schematic diagram, a raw material supply pipe 4 for supplying a raw material vaporized through a raw material vaporizer 5 and a carrier gas supply pipe 6 are provided at the top of the vertical heating furnace 1 (inner diameter 170 mm, length 1500 mm). I installed it.
From the raw material supply pipe 4, toluene in which 3% by mass of ferrocene and 1% by mass of thiophene were dissolved was vaporized and supplied at a rate of 20 g / min, and hydrogen was used as a carrier gas to supply and react at 75 liters / min. FIG. 6 shows a transmission electron micrograph of the fine carbon fiber obtained by this reaction.
The fine carbon fiber obtained by this reaction was heat-treated at 1300 ° C. in an Ar (argon) atmosphere, and the product treated at 1300 ° C. was further heat-treated at 2800 ° C. in an Ar atmosphere to obtain a fine carbon fiber at a weight recovery of 96%.
Further, 4% by mass of B 4 C was mixed with the heat-treated product of the fine carbon fiber in an Ar atmosphere at 1300 ° C. and heat-treated at 2800 ° C. in an Ar atmosphere to obtain a fine carbon fiber with a weight recovery of 94%. This transmission electron micrograph is shown in FIG.
6 and 7 both have a multilayer structure in which cylindrical carbon sheets made of carbon atoms overlap, and the central axis thereof is a hollow structure. However, although FIG. 6 corresponds to the schematic diagram of FIG. 1 and the tip is closed, FIG. 7 shows a multilayer structure having a form roughly corresponding to the schematic diagram of FIG.
That is, in FIG. 7, an outer peripheral portion (corresponding to 14 and 15 in FIG. 3) that forms a cylinder whose tip is open, an intermediate portion (corresponding to 13 in FIG. 3) whose tip is closed, and further inside And a cylinder having an open end (corresponding to 11 and 12 in FIG. 3). In addition, the ends of the carbon sheets (corresponding to 14, 15 and 11, 12 in FIG. 3) constituting the outer side and the inner side of the multilayer structure are connected to each other by being folded back. The carbon sheet (corresponding to 13 in FIG. 3), which is intermediate between the layers of the folded carbon sheet on the outside and the inside of the multilayer structure, has a closed end (corresponding to 12A in FIG. 3). In FIG. 7, a carbon sheet is seen in the cross-sectional direction of the fiber at the tip of the carbon fiber. In this carbon sheet, the folded portion of the carbon sheet on the outer peripheral portion is seen as a carbon sheet, and the axial center of the fiber is There is no carbon sheet in the part. Similarly, at the end of the carbon fiber, the tip of the carbon sheet at the closed end of the intermediate carbon sheet appears to be not hollow but some substance is present, but amorphous carbon adheres to this part. It is not related to the structure of the carbon fiber. It can be seen that amorphous carbon is also present on the circumferential surface of the carbon fiber.
このときの繊維の外径は、約１０〜１００nmでアスペクト比数１０以上の繊維が生産された。また、透過型電子顕微鏡にて観察したところ、上記特徴を持った繊維が半数以上であった。 At this time, fibers having an outer diameter of about 10 to 100 nm and an aspect ratio of several tens or more were produced. When observed with a transmission electron microscope, more than half of the fibers had the above characteristics.
１…縦型加熱炉
２…加熱炉用ヒーター
３…原料回収系
４…原料供給管
５…原料気化器
６…キャリヤーガス供給管
DESCRIPTION OF SYMBOLS 1 ... Vertical heating furnace 2 ... Heating furnace heater 3 ... Raw material recovery system 4 ... Raw material supply pipe 5 ... Raw material vaporizer 6 ... Carrier gas supply pipe
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| WO2009110570A1 (en) * | 2008-03-06 | 2009-09-11 | 宇部興産株式会社 | Fine carbon fiber, fine short carbon fiber, and manufacturing method for said fibers |
| WO2010114089A1 (en) * | 2009-04-02 | 2010-10-07 | 宇部興産株式会社 | Conductive resin composition |
| WO2011016536A1 (en) * | 2009-08-07 | 2011-02-10 | 宇部興産株式会社 | Conductive resin composition |
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| WO2009110570A1 (en) * | 2008-03-06 | 2009-09-11 | 宇部興産株式会社 | Fine carbon fiber, fine short carbon fiber, and manufacturing method for said fibers |
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| WO2010114089A1 (en) * | 2009-04-02 | 2010-10-07 | 宇部興産株式会社 | Conductive resin composition |
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| WO2011016536A1 (en) * | 2009-08-07 | 2011-02-10 | 宇部興産株式会社 | Conductive resin composition |
| WO2011016535A1 (en) * | 2009-08-07 | 2011-02-10 | 宇部興産株式会社 | Conductive polyamide resin composition |
| JP5605364B2 (en) * | 2009-08-07 | 2014-10-15 | 宇部興産株式会社 | Conductive resin composition |
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