JP5194455B2 - Catalyst for producing vapor grown carbon fiber and vapor grown carbon fiber - Google Patents

Catalyst for producing vapor grown carbon fiber and vapor grown carbon fiber Download PDF

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JP5194455B2
JP5194455B2 JP2007011424A JP2007011424A JP5194455B2 JP 5194455 B2 JP5194455 B2 JP 5194455B2 JP 2007011424 A JP2007011424 A JP 2007011424A JP 2007011424 A JP2007011424 A JP 2007011424A JP 5194455 B2 JP5194455 B2 JP 5194455B2
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義郎 笹尾
裕 福山
恵美 三浦
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Mitsubishi Chemical Corp
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Description

本発明は、気相成長法により炭素繊維を製造するための触媒と、この触媒を用いて製造される気相成長炭素繊維に係り、特に、気相成長時の繊維の絡み合いを抑制することにより、炭素繊維凝集体内部の空隙を広げ、これにより、樹脂含浸性を高めた気相成長炭素繊維と、この気相成長炭素繊維を製造するための触媒に関する。   The present invention relates to a catalyst for producing carbon fiber by a vapor growth method and a vapor growth carbon fiber produced using this catalyst, and in particular, by suppressing the entanglement of fibers during vapor growth. The present invention relates to a vapor-grown carbon fiber having an enlarged void inside the carbon fiber aggregate, thereby improving the resin impregnation property, and a catalyst for producing the vapor-grown carbon fiber.

本発明により提供される気相成長炭素繊維は、その優れた樹脂含浸性により、樹脂に配合したときの分散性及び導電性の発現性に優れ、少ない配合量で高い導電性を有する樹脂成形体を提供することができる。   The vapor-grown carbon fiber provided by the present invention has excellent resin impregnating properties, and is excellent in dispersibility and conductivity when blended in a resin, and has a high conductivity with a small blending amount. Can be provided.

一般に、カーボンナノファイバーまたはカーボンナノチューブと称される、直径が1μm以下の微細炭素繊維(以下、単位「炭素繊維」と言う。)は、例えば樹脂へ配合され、導電性や強度等の特性を付与するフィラーとして、種々の検討がなされている。そして、このような炭素繊維は、従来、主にアーク放電法、レーザー蒸着法、気相成長法などで製造されていた。   In general, fine carbon fibers called carbon nanofibers or carbon nanotubes with a diameter of 1 μm or less (hereinafter referred to as units “carbon fibers”) are blended into a resin, for example, to impart properties such as conductivity and strength. Various investigations have been made as fillers. Such carbon fibers have heretofore been produced mainly by an arc discharge method, a laser vapor deposition method, a vapor phase growth method or the like.

このうちアーク放電法やレーザー蒸着法では、真空装置、高電圧大電流電源等、高価且つ取り扱いも注意を要する大型装置を必要とし、加えて炭素繊維の生成量も少ないという問題があった。更に、これらの方法によって得られる炭素繊維は、回収物の中に繊維形状とは異なる黒鉛やアモルファスカーボン等といった不純物を多く含み、生成効率が低いという問題もあった。   Among them, the arc discharge method and the laser vapor deposition method have a problem in that they require a large apparatus that is expensive and requires careful handling, such as a vacuum apparatus and a high-voltage high-current power supply, and that the amount of carbon fiber produced is small. Furthermore, the carbon fiber obtained by these methods has a problem that the recovered product contains a large amount of impurities such as graphite and amorphous carbon which are different from the fiber shape, and the production efficiency is low.

このような課題に対し、炭化水素や一酸化炭素等の炭素を含む原料ガスを、触媒金属上で熱分解して繊維状炭素を得る方法(気相成長法)による炭素繊維の製造方法が提案されている。気相成長法は、アーク放電法やレーザー蒸着法に比べて効率良く不純物の少ない炭素繊維が得られるという利点がある。また、気体状態の原料を使用することによって、連続反応が可能であり、更には原料ガスとなる炭化水素や一酸化炭素等の炭素を含むガスが安価に入手できるので、炭素繊維の量産化に適した技術といえる。   In response to such problems, a carbon fiber manufacturing method using a method (vapor phase growth method) in which a raw material gas containing carbon such as hydrocarbon or carbon monoxide is thermally decomposed on a catalytic metal is proposed. Has been. The vapor phase growth method has an advantage that carbon fibers with less impurities can be obtained more efficiently than the arc discharge method or the laser vapor deposition method. In addition, by using a raw material in a gaseous state, continuous reaction is possible, and further, gas containing carbon such as hydrocarbon and carbon monoxide, which is a raw material gas, can be obtained at low cost. This is a suitable technology.

気相成長法で使用される触媒(以下、「気相成長法炭素繊維製造用触媒」ということがある。)は、例えばシリカ、アルミナ、マグネシア、ゼオライト等の担体に、鉄、コバルト、ニッケル等の遷移金属を担持させたもの、さらにはこれらにモリブテンを含むもの等が提案されている。また、これらの触媒は、一般的に遷移金属が酸化物として存在しているため、水素、アンモニア等によって還元処理を施して触媒を活性化した後に使用される。   Catalysts used in the vapor phase growth method (hereinafter sometimes referred to as “catalysts for vapor phase growth carbon fiber production”) are, for example, carriers such as silica, alumina, magnesia, zeolite, iron, cobalt, nickel, etc. Those having a transition metal supported thereon, and those containing molybdenum are proposed. In addition, since these transition metals generally exist as oxides, these catalysts are used after activating the catalyst by performing a reduction treatment with hydrogen, ammonia or the like.

従来、気相成長炭素繊維製造用触媒として、硝酸金属塩とクエン酸を含む混合物を乾燥し、700℃で5時間焼成して得られた気相成長炭素繊維製造用触媒を用いて、チューブ部分が多層の炭素繊維を得る方法が提案されている(例えば非特許文献1参照)。この方法では、高温での焼成条件のため触媒粒子がシンタリングを生じやすく、その結果、炭素繊維析出効率が低く、生成した炭素繊維中に触媒不純物が数10%以上残留し、生産性が著しく低かった。   Conventionally, as a catalyst for producing a vapor-grown carbon fiber, a tube portion is prepared by using a catalyst for producing a vapor-grown carbon fiber obtained by drying a mixture containing a metal nitrate and citric acid and calcining at 700 ° C. for 5 hours. Has proposed a method for obtaining a multi-layer carbon fiber (see, for example, Non-Patent Document 1). In this method, the catalyst particles are likely to sinter due to the firing conditions at a high temperature. As a result, the carbon fiber deposition efficiency is low, catalyst impurities remain in the produced carbon fiber by several tens of percent, and the productivity is remarkably high. It was low.

触媒粒子のシンタリングによる失活を抑制することにより、気相成長炭素繊維の製造効率を改善する技術も提案されているが(特許文献1)、生成効率は十分とは言えず、その炭素繊維中の残触媒の多さから樹脂コンパンドのフィラーとしては適正とはいえない。これは触媒原料を一度溶液混合し乾燥処理を後に焼成しているために触媒均一性には優れるが、乾燥工程を経ることで触媒が強固に凝集し、焼成時の有機物分解による多孔質化作用が不十分になり炭素繊維析出に必要な成分の露出度が減少するからである。また製造された炭素繊維においてもこのように凝集した触媒構造特性に起因する成長時における繊維同士の絡まりが多く樹脂浸透性に劣ることが予想される。   Although a technique for improving the production efficiency of vapor-grown carbon fiber by suppressing deactivation due to sintering of catalyst particles has been proposed (Patent Document 1), the production efficiency is not sufficient, and the carbon fiber is not sufficient. Due to the large amount of residual catalyst, it is not appropriate as a filler for resin compounds. This is excellent in catalyst uniformity because the catalyst raw materials are mixed once in the solution and calcined after drying. However, the catalyst is strongly aggregated through the drying process and becomes porous due to decomposition of organic substances during calcination. This is because the amount of exposure of the components necessary for carbon fiber deposition decreases. Further, it is expected that the produced carbon fiber is inferior in resin permeability due to many entanglements between fibers at the time of growth due to the aggregated catalyst structure characteristics.

一方、ゼオライト担持型触媒を粒径10μm以下に粉砕処理することにより、1〜2層の炭素繊維の生成量を増加させる方法も提案されているが(特許文献2)、乾燥ゼオライトを担持材として直接使用する方法では焼成時にコバルト金属を均一にゼオライト表面に担持させることが困難であり、触媒あたりの炭素繊維生成量が非常に低く、量産性に優れているとはいえず、フィラー材料として炭素繊維を使用するためには触媒成分の除去が必要となる。さらに1〜6nmの微細繊維では繊維の強度が十分といえず、また比表面積の増加にともない樹脂中における分散が困難になることが予想される。   On the other hand, a method for increasing the amount of carbon fiber in one or two layers by grinding a zeolite-supported catalyst to a particle size of 10 μm or less has been proposed (Patent Document 2). In the direct use method, it is difficult to uniformly support cobalt metal on the zeolite surface at the time of calcination, and the amount of carbon fibers generated per catalyst is very low, and it cannot be said that the mass productivity is excellent. In order to use the fiber, it is necessary to remove the catalyst component. Furthermore, it is expected that fine fibers having a diameter of 1 to 6 nm do not have sufficient fiber strength, and dispersion in the resin becomes difficult as the specific surface area increases.

炭素繊維において、樹脂に対する分散性は、少ない配合量で優れた導電性を得る上で極めて重要な特性である。即ち、炭素繊維を配合することにより、樹脂に対して導電性を付与することができるが、樹脂に対する分散性の悪い炭素繊維では、少ない配合量で高い導電性を得ることができず、樹脂における分散を改善するために長時間の混練を行うことは樹脂劣化を招き適切ではない。炭素繊維の配合量を多くすることにより、導電性を高めることができるが、炭素繊維の配合量を多くすることは、コストの増加のみならず、樹脂の成形性、得られる樹脂成形体の機械的特性を損なうこととなり好ましいことではない。
生成効率の低い炭素繊維も同様であり、不純物である触媒を多量に含む場合、その影響を取り除くためには触媒の洗浄による不純物の除去といった多くの工程を必要とし、工業的に優れているとはいえない。
In the carbon fiber, the dispersibility with respect to the resin is a very important characteristic for obtaining excellent conductivity with a small amount of the compound. That is, by blending carbon fiber, conductivity can be imparted to the resin, but carbon fiber having poor dispersibility with respect to the resin cannot obtain high conductivity with a small blending amount. It is not appropriate to perform kneading for a long time in order to improve dispersion, which causes resin deterioration. Increasing the amount of carbon fiber can increase conductivity, but increasing the amount of carbon fiber increases not only the cost but also the moldability of the resin and the machine of the resulting resin molded body. This is not preferable because it impairs the mechanical characteristics.
The same applies to low-efficiency carbon fibers. When a large amount of impurities, which are impurities, is contained, many steps such as removal of impurities by washing the catalyst are required to remove the effects, and it is industrially superior. I can't say that.

また、反応条件から収率を改善させた例としては基盤法において、原料ガス中のHOを1000ppm未満で管理して炭素繊維の成長効率を高める方法があるが(特許文献3)、基盤法ではその限られた表面積から、全体的な収量が低く、またHO管理も生産性を重視した安価な原料ガスを取り扱うにあたってはその濃度を極限まで下げざるを得ず、管理基準としては適切でない。 As an example of improving the yield from the reaction conditions, there is a method in which the growth efficiency of carbon fiber is increased by managing H 2 O in the raw material gas at less than 1000 ppm in the substrate method (Patent Document 3). In the law, due to its limited surface area, the overall yield is low, and H 2 O management also has to reduce its concentration to the limit when handling inexpensive raw material gas with an emphasis on productivity. not appropriate.

なお、炭素繊維の凝集体を粉砕してその粒径を小さくすることにより、樹脂に対する分散性、導電性発現性を高める技術も提案されているが(特許文献4)、炭素繊維本来の分散性や導電性発現性を改善するものではない。   In addition, although the technique which improves the dispersibility with respect to resin and electroconductivity expression by grind | pulverizing the aggregate of carbon fiber and making the particle size small is proposed (patent document 4), the original dispersibility of carbon fiber is proposed. It does not improve the electrical conductivity.

樹脂中における炭素繊維の分散を改良する技術として、カーボンブラックのストラクチャー構造を表す指標の一つとして一般に使用されているDBP(ジブチルフタレート)吸油量に着目し、DBP吸油量を一定以上に上げることで、分散性、導電性を改良する技術が提案されているが(特許文献5)、後述する実施例1、比較例1で明らかにされるように、DBP吸油量だけが炭素繊維の樹脂分散性に影響を与えるとはいえない。
Carbon,41,2949−2959(2003) 特開2006−181477号公報 特開2005−314204号公報 特開2006−143515号公報 特開平7−102112号公報 特開2006−152490号公報
Focusing on DBP (dibutyl phthalate) oil absorption, which is generally used as one of the indices that represent the structure structure of carbon black, as a technology to improve the dispersion of carbon fibers in the resin, raising the DBP oil absorption above a certain level However, as disclosed in Example 1 and Comparative Example 1 described later, only the DBP oil absorption amount is a resin dispersion of carbon fiber. It cannot be said that it affects sex.
Carbon, 41, 2949-2959 (2003) JP 2006-181477 A Japanese Patent Laying-Open No. 2005-314204 JP 2006-143515 A JP-A-7-102112 JP 2006-152490 A

本発明は上記従来の実状に鑑みてなされたものであって、樹脂への分散性及び導電性の発現性に優れた気相成長炭素繊維を効率的に製造するための技術を提供することを目的とする。   The present invention has been made in view of the above-described conventional situation, and provides a technique for efficiently producing a vapor-grown carbon fiber excellent in dispersibility in resin and expression of conductivity. Objective.

本発明者らは、上記課題を解決すべく鋭意検討した結果、コバルト化合物塩とマグネシウム化合物塩の混合物を焼成した後、微細化処理して得られる気相成長炭素繊維製造用触媒を用いることにより、気相成長時の炭素繊維の絡み合いを抑制することで、炭素繊維凝集体構造内部の空隙を広げ、これにより樹脂含浸性を高めることができ、樹脂への分散性及び導電性発現性に優れた気相成長炭素繊維を得ることができることを見出した。   As a result of intensive studies to solve the above-mentioned problems, the present inventors have used a catalyst for producing vapor-grown carbon fiber obtained by calcining a mixture of a cobalt compound salt and a magnesium compound salt and then performing a refinement treatment. By suppressing the entanglement of carbon fibers during vapor phase growth, it is possible to widen the voids inside the carbon fiber aggregate structure, thereby enhancing the resin impregnation property, and being excellent in dispersibility in resins and conductivity development. It has been found that vapor-grown carbon fibers can be obtained.

本発明はこのような知見に基いて達成されたものであり、以下を要旨とする。   The present invention has been achieved on the basis of such findings, and the gist thereof is as follows.

[1] コバルト化合物塩とマグネシウム化合物塩とを含む原料混合物を焼成し、更に微粉砕してなる、気相成長法による炭素繊維製造用触媒であって、該触媒を、圧力0.2MPaの空気に分散・拡散させて粒度分布測定を実施するレーザー回折法による乾式状態での粒度分布測定において、正規分布50%における平均粒子径D50が3μm以下であることを特徴とする気相成長炭素繊維製造用触媒。 [1] cobalt compound by firing a raw material mixture comprising a salt and a magnesium compound salt, obtained by finely grinding, a carbon fiber production catalyst for vapor deposition, the catalyst, the pressure 0.2MPa air dispersed and allowed to diffuse in the particle size distribution measurement in the dry state by a laser diffraction method to implement the particle size distribution measurement, vapor-grown carbon wherein an average particle diameter D 50 in the normal distribution 50% is 3μm or less Catalyst for fiber production.

[2] [1]において、平均粒子径D50が1μm以下であることを特徴とする気相成長炭素繊維製造用触媒。 [2] The catalyst for producing vapor grown carbon fiber according to [1], wherein the average particle diameter D 50 is 1 μm or less.

[3] [1]又は[2]において、コバルトとマグネシウムとの合計100モル%に対するコバルトの含有割合が10〜50モル%であることを特徴とする気相成長炭素繊維製造用触媒。 [3] The catalyst for producing vapor-grown carbon fibers according to [1] or [2], wherein the content ratio of cobalt is 10 to 50 mol% with respect to 100 mol% in total of cobalt and magnesium.

[4] [1]ないし[3]のいずれかにおいて、該焼成を500℃以下で行うことを特徴とする気相成長炭素繊維製造用触媒。
[5] [1]ないし[4]のいずれかにおいて、残炭分が10重量%以下であることを特徴とする気相成長炭素繊維製造用触媒
[4] The catalyst for producing vapor grown carbon fiber according to any one of [1] to [3], wherein the calcination is performed at 500 ° C. or lower.
[5] The catalyst for producing vapor grown carbon fiber according to any one of [1] to [4], wherein a residual carbon content is 10% by weight or less .

] 気相成長法により製造された炭素繊維において、微細な繊維が絡み合って集合した凝集体構造を有し、水銀加入法による細孔容量測定において、孔径20nm〜4μmの範囲の細孔として測定される空隙を2.4ml/g以上有することを特徴とする気相成長炭素繊維。 [ 6 ] The carbon fiber produced by the vapor phase growth method has an aggregate structure in which fine fibers are entangled and gathered, and in pore volume measurement by the mercury addition method, pores in the pore diameter range of 20 nm to 4 μm are obtained. Vapor growth carbon fiber characterized by having a measured void of 2.4 ml / g or more.

] []において、前記空隙を3ml/g以上有することを特徴とする気相成長炭素繊維。 [ 7 ] The vapor grown carbon fiber according to [ 6 ], wherein the void is 3 ml / g or more.

] []又は[]において、[1]ないし[5]のいずれかの気相成長炭素繊維製造用触媒を用いて製造されたことを特徴とする気相成長炭素繊維。 [ 8 ] A vapor-grown carbon fiber produced by using the vapor-grown carbon fiber production catalyst according to any one of [1] to [5] in [ 6 ] or [ 7 ].

] [6]ないし[]のいずれかにおいて、透過型電子顕微鏡による繊維の観察から算出された内径が3〜13nmで、同外径が6〜30nmであり、炭素が同心円状に少なくとも3層以上の多層にわたり積層した構造を有することを特徴とする気相成長炭素繊維。 [ 9 ] In any one of [6] to [ 8 ], the inner diameter calculated from observation of the fiber with a transmission electron microscope is 3 to 13 nm, the outer diameter is 6 to 30 nm, and the carbon is at least concentrically. A vapor-grown carbon fiber having a structure in which three or more layers are laminated.

10] [6]ないし[]のいずれかにおいて、COを50〜95体積%含み、かつ、HOを0.1〜1体積%含む原料ガスから製造されたことを特徴とする気相成長炭素繊維。 [ 10 ] In any one of [6] to [ 9 ], the gas is produced from a source gas containing 50 to 95% by volume of CO and 0.1 to 1% by volume of H 2 O. Phase-grown carbon fiber.

コバルト化合物塩とマグネシウム化合物塩の混合物を焼成した後、所定の粒子径に微細化処理して得られる本発明の気相成長炭素繊維製造用触媒を用いることにより、気相成長時の炭素繊維の絡み合いを抑制することができ、この結果、炭素繊維凝集体構造内部の空隙が広く、樹脂の含浸性に優れた炭素繊維を効率的に製造することができる。   After firing a mixture of a cobalt compound salt and a magnesium compound salt, by using the catalyst for producing a vapor-grown carbon fiber of the present invention obtained by refining to a predetermined particle diameter, Entanglement can be suppressed, and as a result, carbon fibers having a wide void inside the carbon fiber aggregate structure and excellent resin impregnation can be efficiently produced.

しかして、このような樹脂の含浸性に優れた本発明の気相成長炭素繊維は、樹脂への分散性に優れ、その結果、樹脂成形体における導電性発現性にも優れ、少ない配合量で、従って、樹脂の成形性や樹脂成形体の機械的特性を損なうことなく、優れた導電性樹脂成形体を実現することができる。この導電性樹脂成形体は、帯電防止用電子部材、静電塗装用樹脂成形体、導電性透明樹脂組成物等への応用が可能である。また、本発明の気相成長炭素繊維は成形体以外にも、シート、テープ、透明フィルム、インキ、導電塗料などの樹脂組成物へ適用することができる。   Thus, the vapor-grown carbon fiber of the present invention having excellent resin impregnation property is excellent in dispersibility in the resin, and as a result, is excellent in conductivity expression in the resin molded body, with a small blending amount. Therefore, an excellent conductive resin molded body can be realized without impairing the moldability of the resin and the mechanical properties of the resin molded body. This conductive resin molding can be applied to an electronic member for antistatic, a resin molding for electrostatic coating, a conductive transparent resin composition, and the like. Moreover, the vapor growth carbon fiber of this invention can be applied to resin compositions, such as a sheet | seat, a tape, a transparent film, ink, and a conductive coating, besides a molded object.

以下に本発明の気相成長炭素繊維製造用触媒及び気相成長炭素繊維の実施の形態を詳細に説明する。   Embodiments of the vapor-grown carbon fiber production catalyst and vapor-grown carbon fiber of the present invention will be described in detail below.

[気相成長炭素繊維製造用触媒]
まず、本発明の気相成長炭素繊維製造用触媒について説明する。
本発明の気相成長炭素繊維製造用触媒は、コバルト化合物塩とマグネシウム化合物塩とを含む原料混合物を焼成してなる気相成長法により炭素繊維を製造するための触媒であって、レーザー回折法による乾式状態での粒度分布測定において、正規分布50%における平均粒子径D50が3μm以下であることを特徴とする。
[Catalyst for vapor-grown carbon fiber production]
First, the catalyst for producing vapor grown carbon fiber of the present invention will be described.
The catalyst for producing a vapor-grown carbon fiber of the present invention is a catalyst for producing carbon fiber by a vapor-phase growth method obtained by firing a raw material mixture containing a cobalt compound salt and a magnesium compound salt, and a laser diffraction method In the measurement of the particle size distribution in a dry state according to the above, the average particle diameter D 50 in a normal distribution of 50% is 3 μm or less.

本発明の気相成長炭素繊維製造用触媒は、具体的には、コバルト化合物塩とマグネシウム化合物塩と有機化合物とを十分に混合し、得られた混合物を焼成した後、所定の粒子径になるように微粉砕することにより製造される。   Specifically, the catalyst for producing a vapor-grown carbon fiber of the present invention has a predetermined particle size after sufficiently mixing a cobalt compound salt, a magnesium compound salt, and an organic compound, and firing the obtained mixture. It is manufactured by finely pulverizing.

ここで、コバルト化合物塩は、触媒の活性成分としての酸化コバルトの原料となり、また、マグネシウム化合物塩はこのコバルト活性成分の担体としてのマグネシアの原料となり、有機化合物は、金属を錯体化させることで担持成分に均一に結合させ、且つ、焼成時に分解、気化する際に、活性成分の粒子径を制御する役割を有するための成分として用いられる。   Here, the cobalt compound salt is a raw material of cobalt oxide as an active component of the catalyst, the magnesium compound salt is a raw material of magnesia as a carrier of the cobalt active component, and the organic compound is formed by complexing a metal. It is used as a component that has a role of controlling the particle size of the active component when it is uniformly bonded to the support component and decomposes and vaporizes during firing.

コバルト及びマグネシウム化合物塩は例えば塩化物塩、硝酸塩、硫酸塩、酢酸塩等の無機酸塩や有機酸塩、アンモニア錯体塩、及び金属アルコキシド等が通常用いられるが入手や取り扱いの容易さ等の理由から無機酸塩や有機酸塩が好ましい。これらは1種を単独で用いてもよく、2種以上を混合して用いてもよい。   Cobalt and magnesium compound salts are usually inorganic salts such as chloride salts, nitrates, sulfates, acetates, etc., organic acid salts, ammonia complex salts, metal alkoxides, etc. Therefore, inorganic acid salts and organic acid salts are preferable. These may be used alone or in combination of two or more.

従って、有機化合物としては、コバルト化合物塩と親和し、錯体形成するものが好ましく、同一分子内にカルボキシル基、ヒドロキシル基、アミノ基等を有する有機化合物が挙げられ、具体的にはカルボン酸や、ヒドロキシカルボン酸、カルボン酸エステルなどのカルボン酸誘導体、アミノ酸類、アミド類、アミン類、およびこれらの水和物や無水物などが挙げられる。   Therefore, as the organic compound, those that form a complex with an affinity with the cobalt compound salt are preferable, and examples thereof include organic compounds having a carboxyl group, a hydroxyl group, an amino group, and the like in the same molecule. Examples thereof include carboxylic acid derivatives such as hydroxycarboxylic acid and carboxylic acid ester, amino acids, amides, amines, and hydrates and anhydrides thereof.

これら有機化合物の中でも、分解温度の低いもの、例えば300℃以下で分解するものが好ましく、特に金属との錯形成能を有する(配位子となりうる)化合物は、本発明の触媒において含有されるコバルトの分散性を良好なものとし、且つ微粒子化できるので好ましい。   Among these organic compounds, those having a low decomposition temperature, for example, those capable of decomposing at 300 ° C. or less are preferable. Particularly, a compound having a complex forming ability with a metal (can be a ligand) is contained in the catalyst of the present invention. Cobalt dispersibility is good and fine particles can be formed, which is preferable.

このような有機化合物としては、例えば、クエン酸、リンゴ酸、酒石酸、乳酸、グリシン、グルタミン酸、グルタミン、アスパラギン、アルギニン、フェニルアラニン、アラニン、ロイシン、イソロイシンなどが挙げられる。中でも分解温度が低く、金属との錯形成能に優れるカルボン酸が好ましく、特にクエン酸が好ましい。   Examples of such organic compounds include citric acid, malic acid, tartaric acid, lactic acid, glycine, glutamic acid, glutamine, asparagine, arginine, phenylalanine, alanine, leucine, and isoleucine. Among them, a carboxylic acid having a low decomposition temperature and excellent complex forming ability with a metal is preferable, and citric acid is particularly preferable.

触媒の製造に用いるコバルト化合物塩とマグネシウム化合物塩との割合は、得られる触媒中のコバルトとマグネシウムとの合計100モル%に対するコバルトの含有割合(以下、この割合を単に「コバルト含有率」と称す。)が10〜50モル%、特に20〜40モル%となるような量であることが好ましい。触媒中のコバルト含有率が上記範囲よりも少ないと、触媒活性が低く、炭素繊維生成量が低くなり、逆に、コバルト含有率が上記範囲よりも多いと、コバルト粒子径が過大となり、炭素繊維成長点の減少や触媒として寄与しないコバルトの増加が生じ、効率が低下する。   The ratio of the cobalt compound salt and the magnesium compound salt used for the production of the catalyst is the content ratio of cobalt to the total 100 mol% of cobalt and magnesium in the obtained catalyst (hereinafter, this ratio is simply referred to as “cobalt content ratio”). Is preferably 10 to 50 mol%, particularly 20 to 40 mol%. If the cobalt content in the catalyst is less than the above range, the catalyst activity is low and the amount of carbon fiber produced is low. Conversely, if the cobalt content is more than the above range, the cobalt particle diameter becomes excessive, and the carbon fiber A decrease in growth point and an increase in cobalt which does not contribute as a catalyst occur, resulting in a decrease in efficiency.

また、有機化合物は、コバルト化合物塩とマグネシウム化合物塩との合計に対して10〜60重量%、特に15〜40重量%の割合で用いることが好ましい。この範囲よりも有機化合物使用量が多いと、焼成分解時の発熱反応から触媒のシンタリングを引きおこし、少ないとコバルトの粒径抑制がうまくいかなくなる。   Moreover, it is preferable to use an organic compound in the ratio of 10 to 60 weight% with respect to the sum total of cobalt compound salt and magnesium compound salt, especially 15 to 40 weight%. If the amount of the organic compound used is larger than this range, the sintering of the catalyst is caused from the exothermic reaction at the time of calcination decomposition.

コバルト化合物塩とマグネシウム化合物塩と有機化合物とは、乳鉢等を用いて、工業レベルでは2軸ミキサー、ホモミキサー、ホモジナイザー、ブレンダーミル、自動乳鉢等を用いて十分に混合撹拌する。なお、コバルト化合物塩とマグネシウム化合物塩と有機化合物との混合は乾式混合法限定されず混合攪拌促進のため溶解しない程度に水を含浸させる方式を用いても良い。   The cobalt compound salt, the magnesium compound salt, and the organic compound are sufficiently mixed and stirred using a mortar or the like using a biaxial mixer, a homomixer, a homogenizer, a blender mill, an automatic mortar or the like at an industrial level. The mixing of the cobalt compound salt, the magnesium compound salt, and the organic compound is not limited to the dry mixing method, and a method of impregnating water to such an extent that the mixture is not dissolved to facilitate mixing stirring may be used.

このようにして得られた混合物は空気雰囲気下で、もしくは窒素、アルゴン等の不活性ガス雰囲気下で加熱焼成する。
有機化合物に酸素官能基が多い場合は、自身の分解作用により不活性雰囲気下で十分に焼成可能であるが、有機化合物の酸素官能基量が少ない場合には、焼成雰囲気として空気+窒素混合雰囲気を用いることもできる。この場合、残存酸素が多く、焼成時の温度上昇により触媒のシンタリングが生じる場合には、供給される酸素濃度を低下させることが望ましい。
この焼成は500℃以下、好ましくは450℃以下、さらに好ましくは400℃以下で行われることが好ましい。焼成温度が高すぎると、触媒がシンタリングを生じ、低すぎると有機化合物未分解のため、多量の炭素質不純物が触媒中に残り、炭素繊維における異物の原因となり、またマグネシアへのコバルト粒子の均一担持が不十分となり、いずれも触媒効率の低下の原因となる。
The mixture thus obtained is heated and fired in an air atmosphere or in an inert gas atmosphere such as nitrogen or argon.
If the organic compound has a large number of oxygen functional groups, it can be fired sufficiently in an inert atmosphere due to its decomposition, but if the organic compound has a small amount of oxygen functional groups, the firing atmosphere is an air + nitrogen mixed atmosphere. Can also be used. In this case, when there is a large amount of residual oxygen and the sintering of the catalyst occurs due to a temperature rise during firing, it is desirable to reduce the concentration of supplied oxygen.
This firing is preferably performed at 500 ° C. or lower, preferably 450 ° C. or lower, more preferably 400 ° C. or lower. If the calcination temperature is too high, the catalyst will sinter, and if it is too low, the organic compound will not decompose, so a large amount of carbonaceous impurities will remain in the catalyst, causing foreign matter in the carbon fiber, and the cobalt particles to magnesia Uniform loading is insufficient and both cause a reduction in catalyst efficiency.

焼成により、コバルト化合物塩及びマグネシウム化合物塩はそれぞれ酸化コバルト及びマグネシアとなり、酸化コバルトがマグネシアに担持された触媒が得られる。なお、有機化合物は燃焼により、分解・気化し、排出される。炭素繊維析出反応を阻害されないためにも、触媒表面を清浄化させる必要があり、残炭分が焼成後触媒中の10重量%以下、好ましくは5重量%以下になることが望ましい。   By calcination, the cobalt compound salt and the magnesium compound salt become cobalt oxide and magnesia, respectively, and a catalyst in which cobalt oxide is supported on magnesia is obtained. Organic compounds are decomposed, vaporized and discharged by combustion. In order not to inhibit the carbon fiber precipitation reaction, it is necessary to clean the catalyst surface, and it is desirable that the residual carbon content is 10% by weight or less, preferably 5% by weight or less in the catalyst after calcination.

本発明においては、このようにして得られた焼成物を更に微粉砕して平均粒子径D50が3μm以下、好ましくは1μm以下の微粒子状触媒とする。 In the present invention, thus calcined product was further finely pulverized average particle diameter D 50 obtained is 3μm or less, preferably less particulate catalyst 1 [mu] m.

この微粉砕手段としては特に制限はないが、ピンミル、ハンマーミル、パルペライザー、ジェットミル等を用いることができる。例えば、このジェットミルによる微粉砕時に、圧縮気体(通常、空気もしくは窒素が用いられる。)の圧力を制御するか、後段への分級機設置により粉砕粒度を調整して、所望の粒径の微粒子状触媒を得ることができる。   Although there is no restriction | limiting in particular as this fine grinding | pulverization means, A pin mill, a hammer mill, a pulverizer, a jet mill etc. can be used. For example, fine particles having a desired particle size can be obtained by controlling the pressure of compressed gas (usually air or nitrogen) during fine pulverization by the jet mill or adjusting the pulverization particle size by installing a classifier at the subsequent stage. A catalyst can be obtained.

本発明において、触媒の平均粒子径D50が3μmを超えると、本発明で目的とする凝集体構造内部の空隙の大きな炭素繊維を生産性良く得ることができない。平均粒子径D50は特に1μm以下であることが好ましいが、この平均粒子径D50を過度に小さくすることは、低コスト性に優れる乾式粉砕法では困難であり、また、気相成長法による気体−固体接触時による気流同伴によるふきこぼれおよび反応装置への閉塞が懸念されるため平均粒子径D50は通常0.1μm以上とする。 In the present invention, when the average particle diameter D 50 of the catalyst is more than 3 [mu] m, it is impossible to a large carbon fiber aggregates structure hollow space of interest obtained with good productivity by the present invention. The average particle diameter D 50 is particularly preferably 1 μm or less. However, it is difficult to reduce the average particle diameter D 50 excessively by a dry pulverization method excellent in low cost, and by a vapor phase growth method. gas - average particle diameter D 50 for closure are concerned to boiling over and the reactor according to the air flow entrained by the time solid contact is usually 0.1μm or more.

なお、本発明の気相成長炭素繊維製造用触媒の平均粒子径D50は具体的には後述の実施例の項に記載される方法で測定される。 The average particle diameter D 50 of the vapor-grown carbon fiber production catalyst of the present invention is specifically measured by the method described in the Examples section below.

このような本発明の気相成長炭素繊維製造用触媒は、還元雰囲気下で活性化した後、又は還元性ガスと共に炭素繊維原料ガスと接触させて使用される。活性化時における還元性ガスは、水素(H)、アンモニア等を用いることができるが、特にHが好ましく、その濃度は通常は5〜100体積%、特に10体積%以上であることが好ましい。 Such a catalyst for producing a vapor-grown carbon fiber of the present invention is used after being activated in a reducing atmosphere or in contact with a carbon fiber raw material gas together with a reducing gas. As the reducing gas at the time of activation, hydrogen (H 2 ), ammonia or the like can be used, but H 2 is particularly preferable, and the concentration is usually 5 to 100% by volume, particularly 10% by volume or more. preferable.

[気相成長炭素繊維]
次に、本発明の気相成長炭素繊維について説明する。
[Vapor growth carbon fiber]
Next, the vapor growth carbon fiber of the present invention will be described.

本発明の気相成長炭素繊維は、気相成長法により製造された炭素繊維であって、微細な繊維が絡み合って集合した凝集体構造を有し、水銀加入法による細孔容量測定において、孔径20nm〜4μmの範囲の細孔として測定される空隙(以下「20nm〜4μm空隙率」と称す場合がある。)を2.4ml/g以上有するものである。ここで、孔径20nm未満のものは、炭素繊維(カーボンナノチューブ)のチューブ内の空孔に相当すると考えられ、従って、孔径20nm以上の空隙を測定する。孔径4μmを超える空隙は、凝集体内部ではなく分離独立した凝集炭素繊維間の間隔もしくは非常に弱い力で崩壊する凝集体内部を測定しており、樹脂含浸性に大きくは寄与しないことから孔径4μm以下の空隙を測定する。   The vapor-grown carbon fiber of the present invention is a carbon fiber produced by a vapor-phase growth method, and has an aggregate structure in which fine fibers are entangled and aggregated. It has at least 2.4 ml / g of voids measured as pores in the range of 20 nm to 4 μm (hereinafter sometimes referred to as “20 nm to 4 μm porosity”). Here, those having a pore diameter of less than 20 nm are considered to correspond to vacancies in the tube of carbon fiber (carbon nanotube), and accordingly, voids having a pore diameter of 20 nm or more are measured. The voids having a pore diameter exceeding 4 μm are measured not in the aggregate, but in the distance between the separated and separated aggregated carbon fibers or the inside of the aggregate that collapses with a very weak force. The following voids are measured.

ここで、水銀加入法による細孔容量測定において、孔径20nm〜4μmの範囲の細孔として測定される空隙とは、次のようなものである。
細孔容量測定で20nm未満の孔径として観測されるのは一本一本の繊維と繊維とが直に隣接した隙間であり、仮にこの孔径を1次凝集体(図1における10nm前後の小さく鋭いピーク)とみなすと、この繊維同士がさらに寄り集まり複雑に絡まり集合した状態を2次凝集体(図1における20nm〜4μmの範囲の大きくなだらかなピーク)とみなすことができる。
この2次凝集体の空隙が孔径20nm〜4μmの範囲の細孔として測定され、この凝集体を機械的に壊そうとするとその強固に絡まりあった構造から解きほぐすことは困難である。しかしながら、この2次凝集空隙が大きいことで、この隙間に対する樹脂の浸透性が高まり、凝集体内部における樹脂分子の拡散力が効率的に加わることが可能となり、機械的せん断力では分散しきれなかった凝集気相成長炭素繊維の分散を容易にすることができる。
なお、孔径4μm以上の空隙は3次凝集体構造とみなすことができ、これらは比較的弱い力で容易に解きほぐすことができ、しかも大きな塊状であるため導電性及び樹脂分散性に対する改善寄与は低い。
Here, in the pore volume measurement by the mercury addition method, the voids measured as pores having a pore diameter in the range of 20 nm to 4 μm are as follows.
What is observed as a pore diameter of less than 20 nm in the pore volume measurement is a gap where fibers are directly adjacent to each other, and this pore diameter is assumed to be a primary aggregate (small and sharp around 10 nm in FIG. 1). When it is regarded as a peak), a state in which the fibers are further gathered and complicatedly entangled and gathered can be regarded as a secondary aggregate (a large gentle peak in the range of 20 nm to 4 μm in FIG. 1).
The voids of the secondary aggregates are measured as pores having a pore diameter in the range of 20 nm to 4 μm, and when the aggregates are mechanically broken, it is difficult to unravel the strongly entangled structure. However, since the secondary agglomerated voids are large, the permeability of the resin into the gap is increased, and the diffusion force of the resin molecules inside the agglomerates can be added efficiently, and cannot be dispersed by the mechanical shearing force. It is possible to facilitate the dispersion of the coagulated vapor grown carbon fibers.
Note that voids having a pore diameter of 4 μm or more can be regarded as tertiary aggregate structures, and these can be easily unraveled with a relatively weak force, and because they are large aggregates, their contribution to improvement in conductivity and resin dispersibility is low. .

この20nm〜4μm空隙率が2.4ml/g未満であると、良好な樹脂含浸性を得ることができず、樹脂への分散性、導電性発現性に優れた気相成長炭素繊維を提供し得ない。
20nm〜4μm空隙率は特に3ml/g以上であることが好ましい。20nm〜4μm空隙率は大きい程好ましいが、過度に大きいと炭素繊維のかさ密度が低くなりすぎ樹脂混練を行う際に定量フィーダーからの供給が不安定になり適切な混練が困難となるために通常の管理は10ml/g以下が好ましい。
When the porosity of 20 nm to 4 μm is less than 2.4 ml / g, good resin impregnation property cannot be obtained, and vapor grown carbon fiber excellent in dispersibility in resin and conductivity development is provided. I don't get it.
The porosity of 20 nm to 4 μm is particularly preferably 3 ml / g or more. A porosity of 20 nm to 4 μm is preferably as large as possible. However, if it is excessively large, the bulk density of the carbon fiber becomes too low, and the supply from the metering feeder becomes unstable when the resin kneading is performed. Is preferably 10 ml / g or less.

なお、気相成長炭素繊維の20nm〜4μm空隙率は、具体的には後述の実施例の項に記載される方法で測定される。   In addition, the 20 nm-4 micrometer porosity of vapor growth carbon fiber is specifically measured by the method described in the term of the below-mentioned Example.

また、本発明の気相成長炭素繊維は、透過型電子顕微鏡による繊維の観察から算出された内径が3〜13nm、特に4〜8nmで、同外径が6〜30nm、特に8〜20nmであり、炭素繊維のチューブ壁の厚さは2〜5nm程度であることが好ましい。
特に、炭素繊維の内径及び外径が上記範囲であり、また炭素が同心円状に少なくとも3層以上の多層にわたり積層され、且つその積層数が15層未満である構造であることが好ましい。
The vapor-grown carbon fiber of the present invention has an inner diameter of 3 to 13 nm, particularly 4 to 8 nm, and an outer diameter of 6 to 30 nm, particularly 8 to 20 nm, calculated from observation of the fiber with a transmission electron microscope. The thickness of the carbon fiber tube wall is preferably about 2 to 5 nm.
In particular, the carbon fiber preferably has a structure in which the inner diameter and the outer diameter of the carbon fiber are in the above ranges, and the carbon is concentrically laminated over at least three or more layers, and the number of layers is less than 15 layers.

なお、気相成長炭素繊維の内径、外径、及び構造は具体的には後述の実施例の項に記載される方法で測定される。   The inner diameter, outer diameter, and structure of the vapor-grown carbon fiber are specifically measured by the methods described in the Examples section below.

このような本発明の気相成長炭素繊維の製造方法には特に制限はないが、前述の本発明の気相成長炭素繊維製造用触媒を用いることにより、容易に製造することができる。   Although there is no restriction | limiting in particular in the manufacturing method of such a vapor growth carbon fiber of this invention, It can manufacture easily by using the catalyst for vapor growth carbon fiber manufacture of the above-mentioned this invention.

以下に、本発明の気相成長炭素繊維製造用触媒を用いた本発明の気相成長炭素繊維の製造方法について説明する。   Below, the manufacturing method of the vapor growth carbon fiber of this invention using the catalyst for vapor growth carbon fiber manufacture of this invention is demonstrated.

本発明の気相成長炭素繊維を製造するには、触媒として本発明の気相成長炭素繊維製造用触媒を用いて、原料ガスを加熱下、この触媒に接触させて炭素繊維の析出反応を行う。   In order to produce the vapor-grown carbon fiber of the present invention, the catalyst for vapor-grown carbon fiber production of the present invention is used as a catalyst, and the raw material gas is brought into contact with this catalyst under heating to cause a carbon fiber precipitation reaction. .

炭素繊維の原料ガスとしては、従来公知の任意のものを使用でき、例えば、炭素を含むガスとしてメタンやエチレン、アセチレンなどの炭化水素や、一酸化炭素、アルコールなどを用いることができるが、特に一酸化炭素を用いることが好ましい。原料ガス中におけるCO濃度は、通常、50〜95体積%、好ましくは70〜90体積%で用いられる。   As the raw material gas for carbon fiber, any conventionally known gas can be used.For example, hydrocarbons such as methane, ethylene, and acetylene, carbon monoxide, alcohol, and the like can be used as the gas containing carbon. It is preferable to use carbon monoxide. The CO concentration in the raw material gas is usually 50 to 95% by volume, preferably 70 to 90% by volume.

製造時の温度や原料ガスの供給量などは、従来公知の任意の値から、適宜選択し決定すれば良いが、反応温度は650〜480℃、特に600〜520℃が好ましく、反応圧力は5〜40kPa、特に25〜30kPaとすることが好ましい。反応時間は、反応温度や触媒と原料ガスとの接触比率に応じて任意に設定されるが、通常4〜6時間程度である。本発明での反応速度は反応開始から約1時間で最大となり、その後、徐々に失速して反応開始から5〜5.5時間で停止する。従って、反応時間は上記範囲で管理することが好ましい。
反応終了後の原料ガス置換には、通常窒素等の不活性ガスが用いられる。
The temperature at the time of production, the supply amount of the raw material gas, etc. may be appropriately selected and determined from any conventionally known values, but the reaction temperature is preferably 650 to 480 ° C., particularly preferably 600 to 520 ° C., and the reaction pressure is 5 -40 kPa, particularly 25-30 kPa is preferred. The reaction time is arbitrarily set according to the reaction temperature and the contact ratio between the catalyst and the raw material gas, but is usually about 4 to 6 hours. In the present invention, the reaction rate reaches its maximum at about 1 hour from the start of the reaction, and then gradually decreases and stops at 5 to 5.5 hours from the start of the reaction. Therefore, the reaction time is preferably managed within the above range.
An inert gas such as nitrogen is usually used for the replacement of the raw material gas after completion of the reaction.

なお、本発明の気相成長炭素繊維を製造するに当たり、COを主成分とする原料ガスを用い、原料ガス中のHO濃度を0.1〜1体積%、特に0.2〜0.4体積%に制御することにより、触媒あたりの炭素繊維析出量を高めることができ、なお且つ20nm〜4μm空隙率の高い気相成長炭素繊維を高収率で得る事ができる。この所定濃度のHOによる効果は、触媒からの炭素繊維成長時におけるコーキング作用による触媒失活を防ぐことによると推定される。 In producing the vapor-grown carbon fiber of the present invention, a raw material gas containing CO as a main component is used, and the H 2 O concentration in the raw material gas is 0.1 to 1% by volume, particularly 0.2 to 0.00. By controlling to 4% by volume, the amount of carbon fiber deposited per catalyst can be increased, and vapor grown carbon fiber having a high porosity of 20 nm to 4 μm can be obtained in high yield. The effect of this predetermined concentration of H 2 O is presumed to be due to the prevention of catalyst deactivation due to coking action during carbon fiber growth from the catalyst.

このような本発明の気相成長炭素繊維製造用触媒を用いる気相成長炭素繊維の製造方法によれば、微粒子状触媒の酸化コバルト部分を核として、屈曲した炭素繊維が析出、成長し、触媒粒子が微細なため、成長時には隣接した炭素繊維が接触しても容易に反発し合い離れていくことができ、この結果、炭素繊維同士の絡まりが適度に抑制されて、20nm〜4μm空隙率の大きい炭素繊維が得られる。これに対して、微粉砕を行っていない平均粒子径の大きな触媒を用いた場合には、炭素繊維の成長時に炭素繊維同士が接触しても反発、拡散が困難なため、繊維の絡み合いがより密接なものとなり、凝集体内部の空隙の小さい炭素繊維となる。   According to the method for producing a vapor-grown carbon fiber using the catalyst for producing the vapor-grown carbon fiber of the present invention, the bent carbon fiber is precipitated and grown with the cobalt oxide portion of the particulate catalyst as a nucleus, and the catalyst Since the particles are fine, even when adjacent carbon fibers are in contact with each other at the time of growth, they can be easily repelled and separated. As a result, the entanglement between the carbon fibers is moderately suppressed, and the porosity of 20 nm to 4 μm Large carbon fibers are obtained. On the other hand, when a catalyst with a large average particle size that is not pulverized is used, rebound and diffusion are difficult even if the carbon fibers are in contact with each other during the growth of the carbon fibers. It becomes close and becomes a carbon fiber with a small void inside the aggregate.

本発明の気相成長炭素繊維は、屈曲した炭素繊維同士が適度に絡まり合った凝集体構造を有するが、これを樹脂等の充填材として用いる場合は、適宜粉砕処理して用いても良く、本発明の炭素繊維は、粉砕を行った場合でも、その凝集体構造内部の空隙が大きいことによる樹脂含浸性が損なわれることはなく、樹脂分散性、導電性発現性に優れた炭素繊維を得ることができる。   The vapor-grown carbon fiber of the present invention has an aggregate structure in which bent carbon fibers are appropriately entangled with each other, but when this is used as a filler such as a resin, it may be appropriately pulverized and used. Even when the carbon fiber of the present invention is pulverized, the resin impregnation property due to the large void inside the aggregate structure is not impaired, and a carbon fiber excellent in resin dispersibility and conductivity development is obtained. be able to.

以下に実施例を挙げて、本発明を更に具体的に説明するが、本発明はその要旨を超えない限り、以下の実施例に限定されるものではない。   EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

なお、以下の実施例及び比較例で用いた触媒は、次のようにして製造した。
[触媒の製造]
硝酸コバルト六水和物175g、硝酸マグネシウム六水和物356g、及びクエン酸一水和物137gを秤量して混合し、乳鉢で均一になるまですりつぶした。この混合物をセラミックス容器に入れ電気炉を用いて空気雰囲気下、450℃で、1.5時間焼成した(触媒組成:コバルト含有率=30モル%)。
The catalysts used in the following examples and comparative examples were produced as follows.
[Manufacture of catalyst]
175 g of cobalt nitrate hexahydrate, 356 g of magnesium nitrate hexahydrate, and 137 g of citric acid monohydrate were weighed and mixed, and ground in a mortar until uniform. This mixture was placed in a ceramic container and baked in an air atmosphere at 450 ° C. for 1.5 hours using an electric furnace (catalyst composition: cobalt content = 30 mol%).

焼成により得られた焼成物を回収して乳鉢で粉状になるまですりつぶして「比較用触媒B」とした。   The fired product obtained by firing was collected and ground until it became a powder in a mortar to obtain “Comparative Catalyst B”.

また、乳鉢ですりつぶした触媒をさらに微細化させるために、ジェットミル(セイシン企業製「FS−4」)を用いて粉砕を実施した。このとき、ジェットミルの圧縮気体(窒素)の圧力ないし風量を制御することにより粉砕強度を変化させて、「本発明触媒A」と、各種の平均粒子径D50の触媒を得た。 Further, in order to further refine the catalyst ground in the mortar, pulverization was performed using a jet mill (“FS-4” manufactured by Seishin Enterprise). At this time, the pulverization strength was changed by controlling the pressure of the compressed gas (nitrogen) of the jet mill or the air volume to obtain “the catalyst A of the present invention” and various average particle diameter D 50 catalysts.

得られた触媒の粒度分布測定はレーザー回折・散乱法により、以下のようにして行った。
<粒度分布測定>
触媒を、圧力0.2MPaの空気に分散・拡散させて、セイシン企業製「LMS−300」により、測定を実施した。
The particle size distribution of the obtained catalyst was measured by the laser diffraction / scattering method as follows.
<Particle size distribution measurement>
The catalyst was dispersed and diffused in air having a pressure of 0.2 MPa, and measurement was carried out by “LMS-300” manufactured by Seishin Enterprise.

その結果、比較用触媒Bの平均粒子径D50は6.872μmで、本発明触媒Aの平均粒子径D50は0.878μmであった。 As a result, the average particle diameter D 50 of the comparative catalyst B is 6.872Myuemu, average particle diameter D 50 of the present invention Catalyst A was 0.878Myuemu.

[実施例1、比較例1]
<原料ガスの調整>
石油系重質油(エチレンヘビーエンド)の熱分解により発生したガスを成長炭素の主原料とした。この分解ガスのH濃度調整を膜分離装置(宇部興産製:分解膜モジュール410型)を用いて行い、さらにこのガスは飽和ガスであるため脱湿により水分調整を行って原料ガスとした。
この原料ガスの組成(体積%)は、CO=85%、H=10%、CO=3.5%、CH=1%、HO=0.3%、その他微量の重炭化水素ガス成分である。
[Example 1, Comparative Example 1]
<Adjustment of source gas>
Gas generated by pyrolysis of heavy petroleum oil (ethylene heavy end) was used as the main raw material for growth carbon. The H 2 concentration of the cracked gas was adjusted using a membrane separation device (manufactured by Ube Industries, Ltd .: cracked membrane module 410 type). Further, since this gas is a saturated gas, moisture was adjusted by dehumidification to obtain a raw material gas.
The composition (volume%) of this raw material gas is as follows: CO = 85%, H 2 = 10%, CO 2 = 3.5%, CH 4 = 1%, H 2 O = 0.3%, and other trace amounts of heavy carbonization It is a hydrogen gas component.

<炭素繊維の製造>
触媒A(実施例1)又は触媒B(比較例1)108gを耐熱性容器に均一に散布し、その周囲を抑えるためステンレス製カバーにて密閉した。原料ガスの流れは容器に入り触媒と接触した後にカバー外へと排出される。触媒を散布した後窒素パージを行い、容器内の空気を窒素に置換した。装置全体を電気炉にて外周加熱して内部の温度を調整した。窒素を導入しながら500℃前後に到達したら水素を導入し、触媒を活性化処理した。この処理は約1〜1.5時間ほど行った。活性化処理後、原料ガスを導入して析出反応を開始させた。反応開始直後は反応熱による発熱作用により一時的に温度が上昇しその後、反応温度は590℃〜520℃の温度に段階的に下げていき、反応は4.5時間行った。反応容器内の圧力は5〜30KPaの範囲であるが、主な反応圧力は25〜30KPaである。反応終了後は原料ガスを窒素で置換し、電気炉による加熱を停止して、常温まで冷却した。冷却後、カバーを開放して容器内で析出した炭素繊維を回収した。
<Manufacture of carbon fiber>
108 g of Catalyst A (Example 1) or Catalyst B (Comparative Example 1) was uniformly dispersed in a heat-resistant container, and sealed with a stainless steel cover to suppress the periphery. The flow of the raw material gas enters the container and comes into contact with the catalyst, and then is discharged out of the cover. After sparging the catalyst, a nitrogen purge was performed to replace the air in the container with nitrogen. The entire apparatus was heated by an electric furnace to adjust the internal temperature. When the temperature reached around 500 ° C. while introducing nitrogen, hydrogen was introduced to activate the catalyst. This treatment was performed for about 1 to 1.5 hours. After the activation treatment, the raw material gas was introduced to start the precipitation reaction. Immediately after the start of the reaction, the temperature temporarily increased due to the exothermic action of the reaction heat, and then the reaction temperature was gradually lowered to a temperature of 590 ° C. to 520 ° C., and the reaction was carried out for 4.5 hours. The pressure in the reaction vessel is in the range of 5-30 KPa, but the main reaction pressure is 25-30 KPa. After completion of the reaction, the raw material gas was replaced with nitrogen, heating by the electric furnace was stopped, and the mixture was cooled to room temperature. After cooling, the cover was opened and the carbon fibers deposited in the container were collected.

<TEM観察>
透過型電子顕微鏡(日本電子(株)製 型式:JEOL JEM−1230)によって、得られた炭素繊維を観測した。観察は、炭素繊維サンプルをエタノール溶液に超音波分散を行って分散させ、分散試料を測定用メッシュにて採取して行った(観察条件:120kV)。観察の写真より約100本について径の長さを計測し、その数平均値より内径、外径とした。
<TEM observation>
The obtained carbon fiber was observed with a transmission electron microscope (manufactured by JEOL Ltd., model: JEOL JEM-1230). Observation was performed by ultrasonically dispersing a carbon fiber sample in an ethanol solution and collecting the dispersed sample with a measurement mesh (observation condition: 120 kV). About 100 diameters were measured from the photograph of observation, and it was set as the internal diameter and the external diameter from the number average value.

<SEM観察>
走査型電子顕微鏡(日本電子(株)製 型式:JEOL JSM−7401F)によって、得られた炭素繊維の形態観察を実施した。観察は、炭素繊維サンプルを黒鉛導電シート上にそのままの状態で散布して実施した。
<SEM observation>
Morphological observation of the obtained carbon fiber was carried out with a scanning electron microscope (manufactured by JEOL Ltd., model: JEOL JSM-7401F). The observation was carried out by spraying the carbon fiber sample as it was on the graphite conductive sheet.

<細孔分布測定>
水銀加入法による細孔分布測定を行った。測定装置(Micromeritics社製オートポアIII9420型)を用い、細孔の性状によりピークが生じるため、これを切り分けた場合の領域ごとの容量を提供した。孔径20nm未満の容量は炭素繊維1本ごとの空隙と考えられる。20nm〜4μmの空隙は炭素繊維同士が絡みあい成長した際に生じた凝集間の空隙を示していると考えられる。
<Measurement of pore distribution>
The pore distribution was measured by mercury addition method. Using a measuring device (Autopore III9420 manufactured by Micromeritics), a peak was generated due to the properties of the pores. Therefore, a capacity for each region when this was separated was provided. A capacity of less than 20 nm in pore diameter is considered as a void for each carbon fiber. It is considered that the voids of 20 nm to 4 μm indicate voids between aggregates generated when carbon fibers are entangled and grown.

<DBP吸油量測定>
炭素繊維のBDP吸油量は、JIS K6221吸油量A法に従い、DBPアブソープトメーターにより測定を行った。
<Measurement of DBP oil absorption>
The BDP oil absorption of the carbon fiber was measured with a DBP abstract meter according to JIS K6221 oil absorption A method.

<導電性の評価>
東洋精機製作所製プラストミルを用いて、260℃、150rpmの条件にて炭素繊維と樹脂とを表2に示す各種の割合で2分間混練し、炭素繊維/樹脂組成物を得た。樹脂は6ナイロン(三菱エンジニアリングプラスチックス、1010C)を使用した。
プラストミルにて混練を行った炭素繊維/樹脂組成物をプレスして導電評価用のシートを作成した。成型サイズは100×100×2mm(厚さ)の平板であり、加熱用と冷却用の2台のプレス機を用いて作成した。プレス機は東洋精機製作所製ミニテストプレス(ラム径65mm、盤面200×200)を使用し、圧縮力は20MPa(ラム圧)で盤面への加圧力は約1.6MPaとし、温度は260℃で実施した。
得られた成型シートの端を切削し、その両端に銀ペーストを付与後、測定器の端末を当てることで導電率(体積抵抗値)を測定した。測定器にはロレスタEP(三菱化学製)及びハイレスタ(東亜電波製)を使用し、体積抵抗値が10E+6Ω・cm以下のときはロレスタを用い、それ以上のときはハイレスタを用いた。使用したプローブはESP型である。ハイレスタはリング法を用いて、500V、チャージ1分、測定開始後1分後の値を採用した。
<Evaluation of conductivity>
Using a plast mill manufactured by Toyo Seiki Seisakusho, carbon fiber and resin were kneaded for 2 minutes at various ratios shown in Table 2 under the conditions of 260 ° C. and 150 rpm to obtain a carbon fiber / resin composition. As the resin, 6 nylon (Mitsubishi Engineering Plastics, 1010C) was used.
A carbon fiber / resin composition kneaded with a plast mill was pressed to prepare a sheet for evaluating conductivity. The molding size was a flat plate of 100 × 100 × 2 mm (thickness), and was created using two presses for heating and cooling. The press machine is a mini test press (ram diameter 65 mm, board surface 200 × 200) manufactured by Toyo Seiki Seisakusho, the compression force is 20 MPa (ram pressure), the pressure on the board surface is about 1.6 MPa, and the temperature is 260 ° C. Carried out.
The end of the obtained molded sheet was cut, and after applying a silver paste to both ends thereof, the conductivity (volume resistance value) was measured by applying a terminal of a measuring instrument. Loresta EP (manufactured by Mitsubishi Chemical) and Hiresta (manufactured by Toa Denpa) were used as measuring instruments. Loresta was used when the volume resistance value was 10E + 6 Ω · cm or less, and Hiresta was used when the volume resistance value was higher. The probe used is ESP type. Hiresta uses a ring method, and adopted values of 500 V, charge for 1 minute, and 1 minute after the start of measurement.

<結果>
上記炭素繊維の製造により生成した炭素繊維量と、用いた触媒当たりの炭素繊維生成量を表1に示した。
また、製造された炭素繊維の細孔分布測定結果を図1に示すと共に、20nm〜4μm空隙率を表1に示した。
また、製造された炭素繊維のTEM観察による内径及び外径と構造を表1に示し、SEM写真を図2,3に示した。
また、導電性の評価結果を表2に示した。なお、導電性の良否の評価基準は1E+7Ω・cmとした。
<Result>
Table 1 shows the amount of carbon fiber produced by the production of the carbon fiber and the amount of carbon fiber produced per catalyst used.
The pore distribution measurement result of the produced carbon fiber is shown in FIG. 1, and the porosity of 20 nm to 4 μm is shown in Table 1.
In addition, the inner and outer diameters and the structure of the manufactured carbon fiber by TEM observation are shown in Table 1, and SEM photographs are shown in FIGS.
In addition, Table 2 shows the evaluation results of conductivity. In addition, the evaluation criteria of the quality of electroconductivity were 1E + 7 ohm * cm.

Figure 0005194455
Figure 0005194455

Figure 0005194455
Figure 0005194455

<考察>
以上の結果から次のことが分かる。
<Discussion>
The following can be understood from the above results.

平均粒子径D50が1μm以下の微粉砕された触媒Aを用いた実施例1では20nm〜4μmが3.691ml/gと凝集体構造内の空隙の大きい炭素繊維が得られたのに対して、平均粒子径D50が大きい触媒Bを用いた比較例1で得られた炭素繊維は、20nm〜4μm空隙率が1.938ml/gと小さい。また、生成効率も実施例1では36(g−炭素繊維/g−触媒)であるのに対して、比較例1では29(g−炭素繊維/g−触媒)と、生成効率においても触媒Aを用いた実施例1の方が優れた結果となった。 In Example 1 in which finely pulverized catalyst A having an average particle diameter D50 of 1 μm or less was used, carbon fibers with large voids in the aggregate structure were obtained with a diameter of 20 to 4 μm of 3.691 ml / g. , the carbon fibers obtained in Comparative example 1 using a large catalyst B is an average particle diameter D 50 is, 20Nm~4myuemu porosity is small and 1.938ml / g. Further, the production efficiency is 36 (g-carbon fiber / g-catalyst) in Example 1, whereas it is 29 (g-carbon fiber / g-catalyst) in Comparative Example 1, and the production efficiency is also catalyst A. The result of Example 1 using was superior.

なお、実施例1の炭素繊維の凝集体構造内部の空隙が大きいことは、SEM写真において、実施例1の炭素繊維の凝集体表面に凹凸が多いのに対して、比較例1の炭素繊維の凝集体は、表面が比較的平滑であることからも明らかである。   Note that the voids inside the aggregate structure of the carbon fiber of Example 1 are large in the surface of the aggregate of the carbon fiber of Example 1 in the SEM photograph, whereas the carbon fiber of Comparative Example 1 Aggregates are also evident from the relatively smooth surface.

しかして、このように凝集体構造内部の空隙の大きい実施例1の炭素繊維を用いた場合には、樹脂に対して3重量%の配合で十分な導電性が得られるのに対して、比較例1の炭素繊維では、導電性を得るためには8重量%以上の配合が必要となる。
実施例1の炭素繊維と比較例1の炭素繊維とのこのような差異は、用いた触媒の粒度の差にあり、実施例1では、触媒を微粉砕して微粒子化したことにより、炭素繊維成長時の炭素繊維同士の強固な絡まりや凝集が抑制されて、凝集体内の空隙容量が増し、樹脂含浸性に優れた炭素繊維が製造される。
そして、樹脂含浸性に優れることで、より均一分散に適した形態に炭素繊維の凝集構造を制御できる。この結果、導電性の発現性に優れたものとなる。
Thus, when the carbon fiber of Example 1 having a large void inside the aggregate structure is used as described above, sufficient conductivity can be obtained by blending 3% by weight with respect to the resin. In the carbon fiber of Example 1, 8% by weight or more is required to obtain conductivity.
Such a difference between the carbon fiber of Example 1 and the carbon fiber of Comparative Example 1 lies in the difference in the particle size of the catalyst used. In Example 1, the carbon fiber was obtained by pulverizing the catalyst into fine particles. Strong entanglement and aggregation between the carbon fibers during growth are suppressed, the void volume in the aggregate is increased, and carbon fibers excellent in resin impregnation are produced.
And by being excellent in resin impregnation property, the aggregate structure of carbon fibers can be controlled to a form more suitable for uniform dispersion. As a result, the conductivity is excellent.

内部空隙の指標の一つとされるDBP吸油量に関しては、実施例1が256ml/100g、比較例1では258ml/100gとなり、ほぼ同じ値で差は生じていない。しかしながら、導電性発現に関しては、実施例1の方が優れており、本発明の効果がDBP吸油量による空隙値に左右されないことが明らかであり、技術的には全く異なるものである。本発明の効果を比較するためには、水銀加入法による炭素繊維における20nm〜4μm空隙率を測定する方法を用いる必要がある。   Regarding the DBP oil absorption, which is one of the indexes of the internal void, Example 1 is 256 ml / 100 g, and Comparative Example 1 is 258 ml / 100 g. However, with regard to the expression of conductivity, Example 1 is superior, and it is clear that the effect of the present invention is not influenced by the void value due to the DBP oil absorption, and is technically completely different. In order to compare the effects of the present invention, it is necessary to use a method of measuring the porosity of 20 nm to 4 μm in the carbon fiber by the mercury addition method.

[実施例2、比較例2,3]
実施例1で得られた炭素繊維(実施例2)と、比較例1で得られた炭素繊維(比較例2)をそれぞれ粉砕処理した。
粉砕装置としては、ピンミル型粉砕機(槙野産業製:コロプレックス160Z)を用い、回転数を8000〜14000rpmの範囲にて、窒素と空気の混合気体を同伴させて粉砕を行った。粉砕後の炭素繊維は同伴気体によって気力輸送し、集塵用捕集パックにて回収した。
比較のため、比較例1で得られた炭素繊維をそのまま粉砕しないもの(比較例3)も準備した。
炭素繊維と樹脂とを表3に示す各種割合で2軸混練後、射出成型し、その体積抵抗値を測定し、結果を表3に示した。
[Example 2, Comparative Examples 2 and 3]
The carbon fiber obtained in Example 1 (Example 2) and the carbon fiber obtained in Comparative Example 1 (Comparative Example 2) were each pulverized.
As a pulverizer, a pin mill type pulverizer (manufactured by Hadano Sangyo Co., Ltd .: Coroplex 160Z) was used, and pulverization was performed with a mixed gas of nitrogen and air at a rotational speed of 8000 to 14000 rpm. The pulverized carbon fiber was pneumatically transported by entrained gas and collected by a dust collection pack.
For comparison, a carbon fiber obtained in Comparative Example 1 that was not pulverized as it was (Comparative Example 3) was also prepared.
Carbon fibers and resin were biaxially kneaded at various ratios shown in Table 3 and then injection molded. The volume resistance value was measured, and the results are shown in Table 3.

2軸押出機としては日本製鋼所製TEX−30αを用い、樹脂には6ナイロン(三菱エンジニアリングプラスチックス1010C,1005J)を用いた。押出機の温度を250℃に設定し、スクリュー回転数は200〜400rpm、吐出量を15〜30Kg/hの範囲で調整して混練りを実施した。混練手法としては最初に炭素繊維と6ナイロン(1005J)とで炭素繊維濃度8〜12重量%の高濃度マスターバッチを作成し、その後そのマスターバッチと6ナイロン(1010C)とを混練して希釈して各濃度に調整をした。
また、射出成型機としては、日鋼J12USA IIを用い、設定温度は250℃、金型温度は80〜100℃の範囲で、射出速度は40〜80%の範囲にて成型を実施した。金型としては3mm厚さの平板型を用いた。
体積抵抗値の測定は実施例1と同様に行った。
As the twin screw extruder, TEX-30α manufactured by Nippon Steel Works was used, and 6 nylon (Mitsubishi Engineering Plastics 1010C, 1005J) was used as the resin. The temperature of the extruder was set to 250 ° C., the screw rotation speed was 200 to 400 rpm, and the discharge amount was adjusted in the range of 15 to 30 Kg / h, and kneading was performed. As a kneading method, first, a high concentration master batch with carbon fiber concentration of 8 to 12% by weight is made with carbon fiber and 6 nylon (1005J), and then the master batch and 6 nylon (1010C) are kneaded and diluted. To adjust each concentration.
Moreover, as the injection molding machine, Nikko J12USA II was used, and the molding was performed at a set temperature of 250 ° C., a mold temperature of 80 to 100 ° C., and an injection speed of 40 to 80%. A 3 mm thick flat plate mold was used as the mold.
The volume resistance value was measured in the same manner as in Example 1.

Figure 0005194455
Figure 0005194455

表3より明らかなように、炭素繊維の粉砕により、粗大凝集粒子を減少させることによって、特許文献4の記載と同様に導電性の改良効果が認められるが、いずれの場合も、実施例1の炭素繊維を用いた場合の方が導電性は優れていた。
即ち、炭素繊維と樹脂との混練手法や成型手法にかかわらず、20nm〜4μm空隙率が大きい本発明の炭素繊維は、その空隙の効果によって、樹脂含浸性に優れ、より分散し易いこと、そしてこの効果は炭素繊維の粉砕により失われるものではなく、粉砕の如何によらず有効に発揮されることが分かる。
As is apparent from Table 3, by reducing the coarse aggregated particles by pulverizing the carbon fiber, the effect of improving the conductivity is recognized in the same manner as described in Patent Document 4, but in either case, the effect of Example 1 The conductivity when carbon fiber was used was superior.
That is, regardless of the kneading method or molding method of carbon fiber and resin, the carbon fiber of the present invention having a large porosity of 20 nm to 4 μm is excellent in resin impregnation property and more easily dispersed due to the effect of the void. It can be seen that this effect is not lost by the pulverization of the carbon fiber, but is effectively exhibited regardless of the pulverization.

[実施例3〜9、比較例4,5]
前述の触媒の製造法において、粉砕強度を変えて粉砕を行い、表4に示す各平均粒子径D50の触媒を得、この触媒を用いて、実施例1と同様に炭素繊維の製造を行い、得られた炭素繊維の20nm〜4μm空隙率を測定し、結果を表4に示した。
また、各炭素繊維を用いて、実施例1と同様にして、炭素繊維6重量部、樹脂(6ナイロン)94重量部の割合で混合、成型して、同様に導電性の評価を行い、結果を表4に示した。
[Examples 3 to 9, Comparative Examples 4 and 5]
In the production method of the aforementioned catalyst, and milling by changing the crushing strength, obtaining a catalyst of the average particle diameter D 50 shown in Table 4, using this catalyst in the same manner as in Example 1 carried out the production of carbon fibers The porosity of the obtained carbon fiber was measured from 20 nm to 4 μm, and the results are shown in Table 4.
Further, each carbon fiber was mixed and molded at a ratio of 6 parts by weight of carbon fiber and 94 parts by weight of resin (6 nylon) in the same manner as in Example 1, and the conductivity was similarly evaluated. Are shown in Table 4.

Figure 0005194455
Figure 0005194455

表4より明らかなように、20nm〜4μm空隙率が2.9ml/g以上ある炭素繊維を用いた場合は、導電性の目安とした1E+7Ω・cm以下を達成することができ、導電性に優れている。特に、20nm〜4μm空隙率3ml/g以上では良好な結果が示された。また、この20nm〜4μm空隙率は2.4ml/gを境に閾値があると考えられ、これよりも小さい空隙容量では急速に導電性が低下する。   As is clear from Table 4, when carbon fibers having a porosity of 20 nm to 4 μm of 2.9 ml / g or more are used, 1E + 7 Ω · cm or less, which is a measure of conductivity, can be achieved, and the conductivity is excellent. ing. In particular, good results were shown at 20 nm to 4 μm and a porosity of 3 ml / g or more. In addition, it is considered that this 20 nm to 4 μm porosity has a threshold value at a boundary of 2.4 ml / g, and when the void volume is smaller than this, the conductivity rapidly decreases.

実施例1及び比較例1で得られた炭素繊維の細孔分布測定結果を示すチャートである。6 is a chart showing the pore distribution measurement results of carbon fibers obtained in Example 1 and Comparative Example 1. 実施例1で得られた炭素繊維のSEM写真である。2 is a SEM photograph of the carbon fiber obtained in Example 1. 比較例1で得られた炭素繊維のSEM写真である。2 is a SEM photograph of the carbon fiber obtained in Comparative Example 1.

Claims (10)

コバルト化合物塩とマグネシウム化合物塩とを含む原料混合物を焼成し、更に微粉砕してなる、気相成長法による炭素繊維製造用触媒であって、
該触媒を、圧力0.2MPaの空気に分散・拡散させて粒度分布測定を実施するレーザー回折法による乾式状態での該粒度分布測定において、正規分布50%における平均粒子径D50が3μm以下であることを特徴とする気相成長炭素繊維製造用触媒。
A catalyst for carbon fiber production by a vapor phase growth method, which is obtained by calcining a raw material mixture containing a cobalt compound salt and a magnesium compound salt and further pulverizing the mixture,
In the particle size distribution measurement in a dry state by a laser diffraction method in which the catalyst is dispersed and diffused in air having a pressure of 0.2 MPa to measure the particle size distribution, the average particle diameter D 50 in a normal distribution of 50% is 3 μm or less. A catalyst for producing vapor-grown carbon fibers.
請求項1において、平均粒子径D50が1μm以下であることを特徴とする気相成長炭素繊維製造用触媒。 2. The catalyst for producing vapor-grown carbon fiber according to claim 1, wherein the average particle diameter D 50 is 1 μm or less. 請求項1又は2において、コバルトとマグネシウムとの合計100モル%に対するコバルトの含有割合が10〜50モル%であることを特徴とする気相成長炭素繊維製造用触媒。   The catalyst for producing vapor-grown carbon fiber according to claim 1 or 2, wherein a content ratio of cobalt with respect to 100 mol% in total of cobalt and magnesium is 10 to 50 mol%. 請求項1ないし3のいずれか1項において、該焼成を500℃以下で行うことを特徴とする気相成長炭素繊維製造用触媒。   The catalyst for producing vapor-grown carbon fiber according to any one of claims 1 to 3, wherein the calcination is performed at 500 ° C or lower. 請求項1ないし4のいずれか1項において、残炭分が10重量%以下であることを特徴とする気相成長炭素繊維製造用触媒。   The catalyst for producing vapor-grown carbon fiber according to any one of claims 1 to 4, wherein a residual carbon content is 10% by weight or less. 気相成長法により製造された炭素繊維において、微細な繊維が絡み合って集合した凝集体構造を有し、水銀加入法による細孔容量測定において、孔径20nm〜4μmの範囲の細孔として測定される空隙を2.4ml/g以上有することを特徴とする気相成長炭素繊維。   The carbon fiber produced by the vapor deposition method has an aggregate structure in which fine fibers are entangled and aggregated, and is measured as pores having a pore diameter in the range of 20 nm to 4 μm in the pore volume measurement by the mercury addition method. Vapor growth carbon fiber characterized by having voids of 2.4 ml / g or more. 請求項において、前記空隙を3ml/g以上有することを特徴とする気相成長炭素繊維。 The vapor grown carbon fiber according to claim 6 , wherein the voids are 3 ml / g or more. 請求項又はにおいて、請求項1ないし5のいずれか1項に記載の気相成長炭素繊維製造用触媒を用いて製造されたことを特徴とする気相成長炭素繊維。 8. Vapor-grown carbon fiber according to claim 6 or 7, wherein the vapor-grown carbon fiber is produced using the vapor-grown carbon fiber production catalyst according to any one of claims 1 to 5. 請求項6ないしのいずれか1項において、透過型電子顕微鏡による繊維の観察から算出された内径が3〜13nmで、同外径が6〜30nmであり、炭素が同心円状に少なくとも3層以上の多層にわたり積層した構造を有することを特徴とする気相成長炭素繊維。 In any one of claims 6 to 8, a transmission internal diameter calculated from the electron microscope according fibers observations 3~13Nm, Dosoto径a is 6~30Nm, at least three layers or more carbon atoms are concentrically A vapor-grown carbon fiber characterized by having a structure in which a plurality of layers are laminated. 請求項6ないしのいずれか1項において、COを50〜95体積%含み、かつ、HOを0.1〜1体積%含む原料ガスから製造されたことを特徴とする気相成長炭素繊維。 In any one of claims 6 to 9, CO hints 50-95 vol%, and vapor-grown carbon, characterized in that it is manufactured from a raw material gas containing H 2 O 0.1 to 1 vol% fiber.
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