JP2002235279A - Vapor-grown carbon fiber coated with electrical insulator, method for producing the same, and use thereof - Google Patents
Vapor-grown carbon fiber coated with electrical insulator, method for producing the same, and use thereofInfo
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- JP2002235279A JP2002235279A JP2001032697A JP2001032697A JP2002235279A JP 2002235279 A JP2002235279 A JP 2002235279A JP 2001032697 A JP2001032697 A JP 2001032697A JP 2001032697 A JP2001032697 A JP 2001032697A JP 2002235279 A JP2002235279 A JP 2002235279A
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- vapor
- carbon fiber
- grown carbon
- coated
- boron
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、高い熱伝導性を有
しかつ電気絶縁性を有する熱伝導材と合成樹脂、合成ゴ
ム等の組成物からなる複合材に使用される、電気絶縁性
がある熱伝導性フィラーとして適した窒化ホウ素で被覆
された気相法炭素繊維及びその製造方法に関する。BACKGROUND OF THE INVENTION The present invention relates to a composite material composed of a thermally conductive material having high thermal conductivity and electrical insulation and a composition such as synthetic resin and synthetic rubber. The present invention relates to a vapor-grown carbon fiber coated with boron nitride suitable as a certain heat conductive filler and a method for producing the same.
【０００２】[0002]
【従来の技術】一般に炭素繊維（以下「ＣＦ」と略
す。）は、その高強度、高弾性率、高導電性、高熱伝導
性等の優れた性質を有するところからそれらの特性を利
用した各種の複合材料に広く使用されている。またＣＦ
は高強度、高弾性率などの機械的特性を利用した分野の
製品ばかりでなく、近年のエレクトロニクス技術の発展
に伴うパソコン、携帯電話等の電子機器の小型化、高密
度化、高性能化等による発熱のトラブルを、ＣＦあるい
は炭素材料に備わった高い熱伝導性を生かし、これら電
子デバイスや部品等からの放熱用のフィラーへの応用、
またその高導電性を利用して電磁波シールド材、静電防
止材等のための導電性樹脂フィラーとして、あるいは自
動車の軽量化に伴い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素材と
しての用途が期待されている。2. Description of the Related Art In general, carbon fibers (hereinafter abbreviated as "CF") have various properties such as high strength, high elastic modulus, high electrical conductivity, and high thermal conductivity. Widely used for composite materials. Also CF
Are not only products in the field utilizing mechanical properties such as high strength and high elastic modulus, but also downsizing, high density, high performance, etc. of electronic devices such as personal computers and mobile phones with the development of electronics technology in recent years. By taking advantage of the high thermal conductivity of CF or carbon materials, it can be used as a filler for radiating heat from these electronic devices and components.
It is also expected to be used as a conductive resin filler for electromagnetic wave shielding materials, antistatic materials, etc. by utilizing its high conductivity, or as a filler for electrostatic coating on resins as automobiles become lighter. Is coming. Further, 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.
【０００３】従来のＣＦ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される、
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、補強効果を高めるために、繊維径を細くすること、
繊維長を長くすること等により母材との接触面積を大き
くすることが行われている。[0003] Conventional CF is produced by heat-treating and carbonizing fibers such as PAN, pitch, and cellulose.
It is produced as so-called organic carbon fiber. When these are used as fillers of the fiber-reinforced composite material, in order to enhance the reinforcing effect, to reduce the fiber diameter,
It has been practiced to increase a contact area with a base material by elongating a fiber length or the like.
【０００４】しかし、これらのＣＦの製造方法によって
は、その原料となる有機繊維の糸径がせいぜい５〜１０
μｍが限度であるため、繊維径１μｍ以下、特に１０〜
２００ｎｍ程度の微細なＣＦの製造は不可能であった。
また、このような微細なＣＦにおいては、仮に生産でき
たとしても繊維径に対する長さの比（アスペクト比）に
限界があり経済的に製造することはできず、細くてアス
ペクト比の大きいＣＦが要望されているにもかかわらず
工業的に生産されていなかった。[0004] However, depending on the method of producing these CFs, the yarn diameter of the organic fibers used as the raw material is at most 5 to 10
μm is the limit, so the fiber diameter is 1 μm or less, especially 10 to 10 μm.
It was impossible to produce a fine CF of about 200 nm.
Even if such fine CF can be produced, even if it can be produced, there is a limit in the ratio of length to fiber diameter (aspect ratio), and it cannot be produced economically. Despite the demand, it was not produced industrially.
【０００５】一方、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 Ｆｉｂｅ
ｒ）が研究されるようになった。この気相法炭素繊維
（以下「熱分解ＣＦ」と略す。）は、炭化水素等のガス
を金属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１０ｎｍ程度の熱分解ＣＦが得られるこ
とが知られている。On the other hand, in the latter half of the 1980's, the production method of these organic fibers was completely different from that of the organic fibers, and a vapor grown carbon fiber (Vapor Carbon Carbon Fiber) was used.
r) began to be studied. This vapor-grown carbon fiber (hereinafter abbreviated as “pyrolysis CF”) is formed by pyrolysis of a gas such as a hydrocarbon in the presence of a metal catalyst to form pyrolysis CF having a diameter of 1 μm or less and several tens nm. It is known to be obtained.
【０００６】たとえば、ベンゼン等の有機化合物を原料
とし、これをフェロセン等の有機遷移金属化合物の触媒
とともにをキャリアーガスを用いて高温の反応炉に導入
し、基板上に熱分解ＣＦを生成させる方法（特開昭６０
−２７７００号公報）、浮遊状態で熱分解ＣＦを生成さ
せる方法（特開昭６０−５４９９８号公報）、あるいは
反応炉壁に熱分解ＣＦを成長させる方法（特許２７７８
４３４号公報）等が提案されている。これらの方法によ
り生産された熱分解ＣＦは付着熱分解物の除去、結晶性
の向上のために高温で熱処理を行い、最終の気相法炭素
繊維（以下この炭素繊維を「ＶＧＣＦ」と略記する。な
お熱分解ＣＦおよびＶＧＣＦなどを一括して「気相法炭
素繊維」ということもある。）とし、各種の用途に供さ
れていた。[0006] For example, a method in which an organic compound such as benzene is used as a raw material, and this is introduced into a high-temperature reactor using a carrier gas together with a catalyst of an organic transition metal compound such as ferrocene to generate pyrolytic CF on a substrate (Japanese Patent Laid-Open No. 60
No. 27700), a method of generating pyrolysis CF in a floating state (Japanese Patent Application Laid-Open No. 60-54998), or a method of growing pyrolysis CF on a reactor wall (Japanese Patent No. 2778).
434) and the like have been proposed. The pyrolyzed CF produced by these methods is subjected to a heat treatment at a high temperature to remove adhered pyrolysates and to improve crystallinity, and finally vapor-grown carbon fiber (hereinafter, this carbon fiber is abbreviated as “VGCF”). The pyrolysis CF and VGCF are sometimes collectively referred to as "vapor-grown carbon fibers.") And have been used for various purposes.
【０００７】これら製法により、導電性や熱伝導性に優
れ、微細な繊維径を有しアスペクト比の大きいフィラー
材に適した気相法炭素繊維が得られるようになった。こ
れらのＶＧＣＦは１０〜２００ｎｍ程度の直径で、アス
ペクト比１０〜５００程度のものが容易に量産化され、
導電性あるいは熱伝導性フィラー材として導電性樹脂用
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。By these production methods, vapor-grown carbon fibers having excellent conductivity and heat conductivity, having a fine fiber diameter and being suitable for a filler material having a large aspect ratio can be obtained. These VGCFs have a diameter of about 10 to 200 nm and an aspect ratio of about 10 to 500 are easily mass-produced,
It has come to be used as a conductive or heat conductive filler material for fillers for conductive resins and additives for lead-acid batteries.
【０００８】これら気相法炭素繊維は、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。これら気相法炭素繊維は、
従来のＰＡＮ系ＣＦ、ピッチ系ＣＦに比べ黒鉛化により
結晶性が向上し易いが、繊維径が１０〜２００ｎｍ程度
と小さくなった分、黒鉛結晶の成長が困難となり、天然
黒鉛に比べ結晶性は劣る。そこで我々は先にこれらのＶ
ＧＣＦの結晶性を向上させるために、熱分解ＣＦを黒鉛
化する際にホウ素化合物を添加し、ホウ素をＶＧＣＦに
ドーピングさせることにより黒鉛結晶の成長を促進し、
結晶性の向上したＶＧＣＦを得る方法を開発した。These vapor-grown carbon fibers are characterized in shape and crystal structure, and have a structure in which hexagonal carbon crystals are rolled into a cylindrical shape and stacked in a ring shape, and an extremely thin hollow portion is formed at the center thereof. Is a fiber having These vapor grown carbon fibers,
The crystallinity is easily improved by graphitization as compared with conventional PAN-based CFs and pitch-based CFs. However, since the fiber diameter is reduced to about 10 to 200 nm, it becomes difficult to grow graphite crystals, and the crystallinity is lower than that of natural graphite Inferior. So we will first look at these V
In order to improve the crystallinity of the GCF, a boron compound is added when the pyrolytic CF is graphitized, and the VGCF is doped with boron to promote the growth of graphite crystals,
A method for obtaining a VGCF with improved crystallinity was developed.
【０００９】また、電子デバイスの放熱性の向上には、
熱伝導性が高い電気絶縁物質が放熱性フィラーとして必
要となるため、主にアルミナ等が用いられている。特に
近年の電子デバイスの小型化、高密度化に伴い、これま
で以上の熱伝導性の高い放熱性フィラーが求められてお
り、アルミナを真球状にして、複合体中での充填密度を
向上させ熱伝導性を向上させたり、アルミナより更に熱
伝導性の良い窒化アルミ等も放熱フィラーとして用いら
れてきている。特に電子デバイスの放熱用部材としては
電気絶縁性が必要であることが多く、放熱性フィラーと
しても電気絶縁性の高熱伝導性の放熱フィラーが望まれ
ている。In order to improve the heat dissipation of electronic devices,
Alumina or the like is mainly used because an electrically insulating material having high thermal conductivity is required as a heat dissipating filler. In particular, with the recent miniaturization and higher density of electronic devices, heat-radiating fillers with higher thermal conductivity than ever have been demanded.Alumina is made into a true spherical shape to improve the packing density in the composite. Aluminum nitride or the like having improved thermal conductivity or better thermal conductivity than alumina has also been used as a heat-radiating filler. In particular, a heat-dissipating member of an electronic device often requires electrical insulation, and a heat-dissipating filler having high electrical conductivity and electrical insulation is desired as a heat-dissipating filler.
【００１０】現状では、電気絶縁性を必要とする場合に
は熱伝導性に若干不満はあるとしてもアルミナや窒化ア
ルミ等の無機系の微粒子が放熱性フィラーとして用いら
れている。放熱はこれらフィラーの微粒子間の接触点を
経由する伝熱により行われるが、これが放熱量を律速し
ているものであり、これが伝熱のネックとなっている。
一方フィラーは微粒子であるため、伝熱のための接触面
積は小さく、かつ経由すべき接触点が多くなり、放熱性
を大きく減殺している。従って放熱性の改良には、その
接触点数を減らす、例えば細い繊維状の放熱フィラーを
用いることが望ましいことになる。At present, inorganic particles such as alumina and aluminum nitride are used as heat dissipating fillers when electrical insulation is required, even if the thermal conductivity is slightly unsatisfactory. The heat radiation is performed by heat transfer via the contact points between the fine particles of the filler, and this limits the heat release amount, which is a bottleneck of the heat transfer.
On the other hand, since the filler is a fine particle, the contact area for heat transfer is small, and the number of contact points to be passed increases, greatly reducing heat dissipation. Therefore, in order to improve heat dissipation, it is desirable to reduce the number of contact points, for example, to use a thin fibrous heat dissipation filler.
【００１１】[0011]
【発明が解決しようとする課題】本発明は、電子デバイ
ス、電子部品などに使用される、高い熱伝導性を有しか
つ電気絶縁性である複合材のための放熱性フィラーとし
て、微細繊維状の電気絶縁体で被覆された気相法炭素繊
維（以下「被覆ＶＧＣＦ」という。）及びその製造方法
を提供することにある。DISCLOSURE OF THE INVENTION The present invention relates to a fine fibrous filler as a heat-radiating filler for a composite material having high thermal conductivity and electrical insulation used in electronic devices and electronic parts. Vapor-coated carbon fiber coated with an electrical insulator (hereinafter referred to as “coated VGCF”) and a method for producing the same.
【００１２】[0012]
【課題を解決するための手段】本発明者らは、熱分解Ｃ
Ｆの熱処理により結晶性を向上させ、熱伝導性や導電性
を向上させるとともに、表面を電気絶縁体で被覆するこ
とにより、電気絶縁性を有しながら全体としては熱伝導
性に優れた繊維径が極度に小さい被覆ＶＧＣＦの開発に
成功した。Means for Solving the Problems The inventors of the present invention have developed a thermal decomposition C
The heat treatment of F improves the crystallinity, improves the thermal conductivity and conductivity, and coats the surface with an electrical insulator to provide a fiber diameter with electrical insulation and excellent thermal conductivity as a whole. Has successfully developed an extremely small coated VGCF.
【００１３】すなわち本発明は、［１］ 繊維径０．０
１〜０．５μｍの気相法炭素繊維の表面の一部または全
部が電気絶縁体で被覆された電気絶縁体被覆気相法炭素
繊維、［２］ 電気絶縁体が窒化ホウ素であることを特
徴とする上記［１］に記載の電気絶縁体被覆気相法炭素
繊維、［３］ 気相法炭素繊維全量に対して、窒化ホウ
素含有量が２質量％以上、Ｃ０が０．６８０ｎｍ以下で
ある上記［２］に記載の電気絶縁体被覆気相法炭素繊
維、［４］ 気相法炭素繊維の表面から１ｎｍの深さに
おけるホウ素含有量が１０質量％以上であることを特徴
とする上記［２］または［３］に記載の電気絶縁体被覆
気相法炭素繊維、［５］ 嵩密度０．８ｇ／ｃｍ3に圧
密した際の比抵抗が１０3Ω・ｃｍ以上、熱伝導率が１
５０Ｗｍ-1Ｋ-1以上の上記［１］〜［４］のいずれかひ
とつに記載の電気絶縁体被覆気相法炭素繊維、That is, the present invention relates to [1] a fiber diameter of 0.0
An electrical insulator-coated vapor-grown carbon fiber in which a part or all of the surface of a vapor-grown carbon fiber of 1 to 0.5 μm is coated with an electrical insulator, [2] the electrical insulator is boron nitride [3] The boron nitride content is 2% by mass or more and the C0 is 0.680 nm or less based on the total amount of the vapor-grown carbon fibers according to [1]. The electrical insulator-coated vapor-grown carbon fiber according to the above [2], [4] the boron content at a depth of 1 nm from the surface of the vapor-grown carbon fiber is 10% by mass or more. 2] or [3], wherein the electrical insulation coated vapor grown carbon fiber according to [5] has a specific resistance of 10 3 Ω · cm or more and a thermal conductivity of 1 when compacted to a bulk density of 0.8 g / cm 3.
The electric insulator-coated vapor grown carbon fiber according to any one of the above [1] to [4], which has 50 Wm -1 K -1 or more.
【００１４】［６］ 繊維径０．０１〜０．５μｍの気
相法炭素繊維とホウ素化合物を混合し、窒素化合物存在
下、２０００℃以上で熱処理を行うことを特徴とする電
気絶縁体被覆気相法炭素繊維の製造方法、［７］ 繊維
径０．０１〜０．５μｍの気相法炭素繊維とホウ素化合
物を混合し、該混合物を圧縮し、窒素化合物存在下、２
０００℃以上で熱処理を行う窒化ホウ素で被覆された電
気絶縁体被覆気相法炭素繊維の製造方法、［８］ 窒素
化合物が窒素であることを特徴とする上記［６］または
［７］に記載の電気絶縁体被覆気相法炭素繊維の製造方
法、［９］ ホウ素化合物が元素状ホウ素、ホウ酸、ホ
ウ酸塩、酸化ホウ素、Ｂ4Ｃおよび窒化ホウ素からなる
群から選ばれた少なくとも１種である上記［６］〜
［８］のいずれかひとつに記載の電気絶縁体被覆気相法
炭素繊維の製造方法、［１０］ ホウ素化合物と気相法
炭素繊維との混合物のホウ素濃度が、ホウ素元素として
１質量％以上、３０質量％以下であることを特徴とする
上記［６］〜［９］のいずれかひとつに記載の電気絶縁
体被覆気相法炭素繊維の製造方法、[6] An electric insulator coated gas characterized by mixing a vapor-grown carbon fiber having a fiber diameter of 0.01 to 0.5 μm with a boron compound and performing a heat treatment at 2000 ° C. or more in the presence of a nitrogen compound. [7] A vapor-grown carbon fiber having a fiber diameter of 0.01 to 0.5 μm and a boron compound are mixed, and the mixture is compressed.
[8] The method according to [6] or [7], wherein the method is a method for producing a vapor-grown carbon fiber coated with an electrical insulator coated with boron nitride, which is heat-treated at 000 ° C. or more, [8] wherein the nitrogen compound is nitrogen. [9] at least one kind of boron compound selected from the group consisting of elemental boron, boric acid, borate, boron oxide, B 4 C, and boron nitride [6] to
[8] The method for producing an electrical insulator coated vapor grown carbon fiber according to any one of [8], [10] wherein the boron concentration of the mixture of the boron compound and the vapor grown carbon fiber is 1% by mass or more as a boron element; The method for producing a vapor-grown carbon fiber coated with an electric insulator according to any one of the above [6] to [9], which is 30% by mass or less,
【００１５】［１１］ 繊維径０．０１〜０．５μｍの
気相法炭素繊維の表面の一部または全部が電気絶縁体で
被覆された電気絶縁体被覆気相法炭素繊維を含む合成樹
脂または合成ゴム組成物からなる電気絶縁性複合材、
［１２］ 電気絶縁体が窒化ホウ素である上記［１１］
に記載の電気絶縁性複合材、［１３］ 上記［３］〜
［５］のいずれかひとつに記載の電気絶縁体被覆気相法
炭素繊維を含む合成樹脂または合成ゴム組成物からなる
電気絶縁性複合材、および［１４］ 上記［１］〜
［５］のいずれかひとつに記載の電気絶縁体被覆気相法
炭素繊維を含む放熱材料、を開発することにより上記の
目的を達成した。[11] A synthetic resin containing a vapor-grown carbon fiber coated with an electric insulator, wherein a part or the whole of the surface of the vapor-grown carbon fiber having a fiber diameter of 0.01 to 0.5 μm is coated with an electric insulator. An electrically insulating composite material comprising a synthetic rubber composition,
[12] The above-mentioned [11], wherein the electric insulator is boron nitride.
[13] The electrically insulating composite material according to [3] above.
[5] An electric insulating composite material comprising a synthetic resin or a synthetic rubber composition containing the electric insulator-coated vapor grown carbon fiber according to any one of [5], and [14] above.
The object has been achieved by developing a heat-dissipating material containing the vapor-grown carbon fiber coated with an electric insulator according to any one of [5].
【００１６】[0016]
【発明の実施の形態】以下、本発明について詳細に説明
する。 （気相法炭素繊維）本発明で用いるＣＦは、原料として
ベンゼン等の有機化合物を、触媒としてフェロセン等の
有機遷移金属化合物とともに、キャリアーガスを用いて
高温の反応炉に導入し、気相熱分解することにより熱分
解ＣＦを製造する。その繊維径は、０．０１〜０．５μ
ｍで、アスペクト比１０〜５００程度のものである。例
えば、この製造方法としては、基板上に熱分解ＣＦを生
成させる方法（特開昭６０−２７７００号公報）、浮遊
状態で熱分解ＣＦを生成させる方法（特開昭６０−５４
９９８公報号）、あるいは反応炉壁に熱分解ＣＦを成長
させる方法（特許２７７８４３４号公報）等があり、本
発明で使用するＣＦはこれらの方法により製造したもの
であってよい。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. (Vapor-grown carbon fiber) CF used in the present invention is obtained by introducing an organic compound such as benzene as a raw material and an organic transition metal compound such as ferrocene as a catalyst into a high-temperature reaction furnace using a carrier gas, Decompose to produce pyrolysis CF. The fiber diameter is 0.01-0.5μ
m and an aspect ratio of about 10 to 500. For example, as the manufacturing method, a method of generating pyrolytic CF on a substrate (Japanese Patent Application Laid-Open No. 60-27700) and a method of generating pyrolytic CF in a floating state (Japanese Patent Application Laid-Open No. 60-54)
No. 998) or a method of growing pyrolytic CF on a reactor wall (Japanese Patent No. 2778434). The CF used in the present invention may be produced by these methods.
【００１７】このようにして製造された熱分解ＣＦは、
このまま電気絶縁体被覆用原料としてもかまわないが、
この段階では、その表面に原料の有機化合物等に由来す
る熱分解物が付着していることやあるいはＣＦを形成す
る繊維構造の結晶性が不十分である。従ってそれら熱分
解物などの不純物を除いたり、ＣＦとしての結晶構造を
向上させるために、通常は不活性ガス雰囲気下で熱処理
が行われたものを原料としてもよい。原料に由来する熱
分解物等の不純物を処理するためには、約８００〜１５
００℃、アルゴン等の不活性ガス中で熱処理を行う。ま
た、炭素構造の結晶性を向上させるためには、約２００
０〜３０００℃でアルゴン等の不活性ガス中で熱処理を
行われＶＧＣＦとして市販品されている。The pyrolysis CF thus produced is
It may be used as a raw material for electrical insulator coating as it is,
At this stage, thermal decomposition products derived from a raw material organic compound or the like are attached to the surface, or the crystallinity of the fiber structure forming CF is insufficient. Therefore, in order to remove impurities such as thermal decomposition products and to improve the crystal structure of CF, a material which is usually heat-treated in an inert gas atmosphere may be used as a raw material. In order to treat impurities such as thermal decomposition products derived from raw materials, about 800 to 15
Heat treatment is performed at 00 ° C. in an inert gas such as argon. In order to improve the crystallinity of the carbon structure, about 200
It is heat-treated at 0 to 3000 ° C. in an inert gas such as argon and is commercially available as VGCF.
【００１８】電気絶縁体としては、ゴム、プラスチッ
ク、ガラスなどの有機または無機の化合物または組成物
が知られているが、耐熱性、耐薬品性の点で無機化合物
または組成物が好ましく、溶融体、焼結体あるいは膜な
どの形で使用できる。電気絶縁体の体積固有抵抗（Ωｃ
ｍ）としては、１０12以上、好ましくは１０ 15以上あれ
ば良く、例えばアルミナ、サファイヤ、マイカ、シリ
カ、炭化ケイ素、窒化アルミニウム、窒化ホウ素、窒化
ケイ素、サイアロン、酸化マグネシウム、酸化ベリリウ
ム、酸化ジルコニウムなどが使用できるが、好ましくは
窒化ホウ素、窒化ケイ素、炭化ケイ素、より好ましくは
窒化ホウ素である。As the electric insulator, rubber or plastic is used.
Organic or inorganic compounds or compositions such as glass, glass, etc.
Is known, but inorganic compounds in terms of heat resistance and chemical resistance
Or a composition is preferable, and a melt, a sintered body or a film
Available in any form. Volume resistivity of electrical insulator (Ωc
m) is 1012Above, preferably 10 15That's it
For example, alumina, sapphire, mica, silica
Mosquito, silicon carbide, aluminum nitride, boron nitride, nitride
Silicon, sialon, magnesium oxide, beryllium oxide
And zirconium oxide can be used, but preferably
Boron nitride, silicon nitride, silicon carbide, more preferably
Boron nitride.
【００１９】ＶＧＣＦの表面の少なくとも一部を電気絶
縁体で被覆する方法としては、ＶＧＣＦに電気絶縁物を
塗布、蒸着あるいは浸漬することで可能である。特に、
本発明の窒化ホウ素でＶＧＣＦ表面を被覆するために
は、好ましくはホウ素源となるホウ素化合物と気相法炭
素繊維を混合し、これを窒素源となる窒素化合物、例え
ばＮ2、ＮＨ3、尿素、Ｎ2Ｈ4、またはＮＨ3／ＮＯ、Ｎ
Ｈ3／ＮＯ2のような反応してＮ2を発生するものと、特
に窒素ガス（Ｎ2）を含む雰囲気下、好ましくは窒素ガ
ス単独の雰囲気下で、約２０００〜３０００℃で熱処理
を行う。Ｎ２の純度としては、９８％程度以上であれば
使用できるが９９．８％以上、好ましくは９９．９９％
以上がよい。また、被覆条件としては閉鎖系でもあるい
はＮ2気流下の開放系でも必要なＮ2濃度が保持できれば
よい。ここで用いるホウ素化合物は、ＶＧＣＦ表面を被
覆する窒化ホウ素源となるばかりでなく、ＶＧＣＦの炭
素の結晶性を向上させる働きをする。As a method of covering at least a part of the surface of the VGCF with an electric insulator, it is possible to apply, deposit or immerse an electric insulator on the VGCF. In particular,
In order to coat the VGCF surface with the boron nitride of the present invention, preferably, a boron compound serving as a boron source and a vapor grown carbon fiber are mixed, and this is mixed with a nitrogen compound serving as a nitrogen source, for example, N 2 , NH 3 , urea. , N 2 H 4 , or NH 3 / NO, N
A heat treatment is performed at about 2000 to 3000 ° C. in an atmosphere containing a reaction such as H 3 / NO 2 to generate N 2 , and particularly in an atmosphere containing nitrogen gas (N 2 ), preferably in an atmosphere of nitrogen gas alone. . The purity of N2 can be used as long as it is about 98% or more, but 99.8% or more, preferably 99.99%.
The above is good. In addition, the coating conditions may be any as long as the required N 2 concentration can be maintained in a closed system or an open system under an N 2 gas flow. The boron compound used here serves not only as a boron nitride source for coating the surface of the VGCF, but also for improving the crystallinity of carbon of the VGCF.
【００２０】ホウ素源となるホウ素化合物は、ホウ素を
含有する化合物なら殆どの化合物が適用できる。これら
の化合物は２０００℃以上の条件において、雰囲気の窒
素ガスと反応し、ＣＦ表面に窒化ホウ素を生成する化合
物が好ましく、この様な化合物としては例えば、元素状
ホウ素、ホウ酸、ホウ酸塩、酸化ホウ素、Ｂ4Ｃ、ＢＮ
等を挙げることができ、中でもＢ4Ｃ、酸化ホウ素が望
ましい。As the boron compound serving as a boron source, almost any compound containing boron can be used. These compounds are preferably compounds that react with nitrogen gas in the atmosphere at a temperature of 2000 ° C. or higher to generate boron nitride on the CF surface. Examples of such compounds include elemental boron, boric acid, borate, and the like. Boron oxide, B 4 C, BN
Etc., among which B 4 C and boron oxide are preferable.
【００２１】使用するホウ素化合物量は、ホウ素化合物
と気相法炭素繊維との混合物中のホウ素濃度が、ホウ素
元素として１質量％以上、３０質量％以下好ましくは、
２質量％以上２５質量％以下さらに好ましくは、５質量
％以上２０質量％以下の範囲が望ましい。ホウ素濃度が
１質量％未満であると、ＶＧＣＦの結晶性は向上する
が、生成する窒化ホウ素量が少なくＶＧＣＦ表面の被覆
量が不足し、電気絶縁性が不足する。一方ホウ素濃度が
３０質量％以上の場合は、窒化ホウ素がＶＧＣＦ表面を
被覆するばかりでなく、繊維表面に窒化ホウ素の粒子が
生成してしまい、繊維としての機能性を低下させてしま
う。The amount of the boron compound used is such that the boron concentration in the mixture of the boron compound and the vapor grown carbon fiber is 1% by mass or more and 30% by mass or less as a boron element.
The range is preferably from 2% by mass to 25% by mass, more preferably from 5% by mass to 20% by mass. If the boron concentration is less than 1% by mass, the crystallinity of the VGCF is improved, but the amount of boron nitride generated is small and the coating amount on the VGCF surface is insufficient, resulting in insufficient electrical insulation. On the other hand, when the boron concentration is 30% by mass or more, not only the boron nitride coats the VGCF surface, but also boron nitride particles are generated on the fiber surface, thereby deteriorating the functionality as a fiber.
【００２２】原料の微細な繊維としては、原料気相法炭
素繊維をあらかじめ解砕または粉砕したものを用いるこ
とはできる。解砕または粉砕の程度はホウ素またはホウ
素化合物と混合ができる程度で十分である。すなわち、
絶縁体被覆処理（「ＢＮ被覆処理」ともいう。）した後
にも解砕または粉砕あるいは分級等のフィラー化処理を
するので、ＢＮ被覆処理の前に用途に適した適正な長さ
にしなくても該炭素繊維とホウ素またはホウ素化合物と
混合ができれば良い。気相成長法で一般的に得られるＣ
Ｆは、太さ（直径）０．０１〜１μｍ程度、長さ０．５
〜４００μｍ程度であり、そのまま用いることができ
る。またこれらはフロック状の凝集によって生ずる（独
立した粒子とみなし得るような）粒子集合体になってい
てもよい。As the fine fibers of the raw material, those obtained by previously crushing or pulverizing the raw material vapor grown carbon fiber can be used. The degree of pulverization or pulverization is sufficient to allow mixing with boron or a boron compound. That is,
Even after the insulator coating treatment (also referred to as "BN coating treatment"), filler treatment such as crushing, pulverization, or classification is performed. It suffices if the carbon fiber can be mixed with boron or a boron compound. C generally obtained by vapor phase epitaxy
F has a thickness (diameter) of about 0.01 to 1 μm and a length of 0.5
４００400 μm, and can be used as it is. They may also be in the form of particle aggregates (which can be regarded as independent particles) caused by floc-like aggregation.
【００２３】原料の微細な気相法炭素繊維は３次元の立
体構造を持ち、フロック状を形成し易いだけでなく、嵩
密度が極めて小さく空隙率が非常に大きい。しかも添加
するホウ素化合物との比重差が大きいので、単に両者を
混合しただけでは両者を均一に接触させることは難し
い。ホウ素の導入反応を効率よく行うには繊維とホウ素
またはホウ素化合物をよく混合し、できるだけ均一に接
触させる。そのためには、ホウ素化合物の粒子はできる
だけ粒径の小さいものを使用する必要がある。また、粒
子が大きいと部分的に高濃度領域が発生することにな
り、固結化の原因になりかねない。具体的には粒度は平
均粒径で１００μｍ以下、好ましくは５０μｍ以下、よ
り好ましくは２０μｍ以下である。The raw material vapor-grown carbon fiber has a three-dimensional three-dimensional structure, is easy to form a floc, and has a very small bulk density and a very high porosity. Moreover, since the specific gravity difference between the boron compound and the boron compound to be added is large, it is difficult to uniformly contact both by simply mixing the two. In order to carry out the boron introduction reaction efficiently, the fiber and boron or boron compound are mixed well and brought into contact as uniformly as possible. For this purpose, it is necessary to use boron compound particles having the smallest possible particle size. In addition, when the particles are large, a high concentration region is partially generated, which may cause solidification. Specifically, the average particle size is 100 μm or less, preferably 50 μm or less, and more preferably 20 μm or less.
【００２４】また、ホウ素化合物がホウ酸などのように
水溶性であるときはこれを水溶液としてＣＦに添加し、
水分を蒸発させる方法や加熱過程で水分を蒸発する方法
も用いることができる。水溶液を均一に混合すれば水分
蒸発後はホウ素化合物を繊維表面に均一に付着させるこ
とができる。When the boron compound is water-soluble, such as boric acid, it is added as an aqueous solution to CF,
A method of evaporating water or a method of evaporating water during a heating process can also be used. If the aqueous solution is uniformly mixed, the boron compound can be uniformly adhered to the fiber surface after water evaporation.
【００２５】気相法炭素繊維は先に述べたように、嵩密
度が小さく、製造されたままの集合体では約０．０１ｇ
／ｃｍ3以下、またこれを熱処理し、解砕、粉砕、分級
した通常品でも０．０１〜０．０８ｇ／ｃｍ3程度であ
る。従ってこの微細な炭素繊維は多くの空隙率を持つの
で、これをそのままの状態で窒化ホウ素被覆処理するに
は非常に容量の大きな熱処理炉が必要となり、設備コス
トが高くなるだけでなく、生産性も悪い。従って、通常
の炭素材料の場合と異なり、より効率的な方法で窒化ホ
ウ素被覆処理をする必要がある。As described above, the vapor-grown carbon fiber has a low bulk density, and is about 0.01 g in an as-produced aggregate.
/ Cm 3 or less, and about 0.01 to 0.08 g / cm 3 even for a normal product which is heat-treated, crushed, pulverized, and classified. Therefore, since this fine carbon fiber has a large porosity, a very large-capacity heat treatment furnace is required to perform the boron nitride coating treatment as it is, which not only increases the equipment cost but also increases the productivity. Is also bad. Therefore, unlike the case of a normal carbon material, it is necessary to perform the boron nitride coating treatment by a more efficient method.
【００２６】例えば、繊維とホウ素またはホウ素化合物
を均一に混合し、そのまま熱処理することもできるが、
好ましくは高密度化し、且つその状態をできるだけ維持
（固定化）して熱処理する。その好ましい方法として、
本発明では熱処理前に、繊維とホウ素またはホウ素化合
物を混合した後、混合物を加圧、圧縮し、高密度化して
固定化する。この場合、繊維とホウ素またはホウ素化合
物の混合は、均一性が保持できればいずれの方法でも良
い。混合装置としては、均一に混合できれば市販の混合
装置の何れでもよいが、微細な炭素繊維はフロック状に
なり易いので、これを解砕するためにチョッパー付きの
ヘンシェルミキサータイプのものであればより好まし
い。使用する原料繊維は先に述べたように製造されたま
まのものでも、その繊維の１５００℃以下の温度での熱
処理品でもよい。ただ、経済的にも、性能的にも製造さ
れたままのものを混合する方法が好ましい。For example, the fiber and boron or boron compound can be uniformly mixed and heat-treated as it is.
Preferably, the heat treatment is performed while densifying and maintaining (fixing) the state as much as possible. As a preferred method,
In the present invention, before the heat treatment, the fiber is mixed with boron or a boron compound, and then the mixture is pressurized, compressed, densified, and fixed. In this case, any method may be used for mixing the fiber and boron or the boron compound as long as uniformity can be maintained. As the mixing device, any commercially available mixing device may be used as long as it can be uniformly mixed, but fine carbon fibers tend to be floc-shaped. preferable. The raw material fibers used may be as-produced as described above, or may be heat-treated products of the fibers at a temperature of 1500 ° C. or less. However, a method of mixing as-produced products economically and performance-wise is preferred.
【００２７】繊維とホウ素またはホウ素化合物の混合物
を高密度化し、両者が分離しないように固定化する方法
としては、成形法、造粒法、あるいは、混合物をルツボ
等にいれて一定の形状に圧縮して、詰め込む方法等何れ
の方法でも良い。また成形法の場合、成形体の形状は円
柱状、板状や直方体等何れの形状でもよい。As a method of increasing the density of the mixture of the fiber and boron or boron compound and fixing the mixture so that the two do not separate, a molding method, a granulation method, or a method in which the mixture is placed in a crucible or the like and compressed into a certain shape. Then, any method such as a packing method may be used. In the case of the molding method, the shape of the molded body may be any shape such as a columnar shape, a plate shape, and a rectangular parallelepiped.
【００２８】高密度化し、固定された混合物の嵩密度は
０．０２ｇ／ｃｍ3以上、好ましくは０．０３ｇ／ｃｍ3
以上とする。混合物を圧縮して成形体とした後、圧力を
開放すると多少容積が膨らみ、嵩密度が下がることもあ
るが、その場合は圧縮時の嵩密度を圧力開放後の固定化
の嵩密度が０．０２ｇ／ｃｍ3以上になるようにする。
また繊維を容器に入れる場合も、処理効率を上げるため
に、加圧板等を用いて嵩密度が０．０２ｇ／ｃｍ3以上
になるように圧縮したり、また圧縮したまま熱処理する
こともできる。The bulk density of the densified and fixed mixture is at least 0.02 g / cm 3 , preferably 0.03 g / cm 3.
Above. When the pressure is released after compressing the mixture to form a molded body, the volume may slightly increase, and the bulk density may decrease. In this case, the bulk density at the time of compression is reduced to 0. It should be at least 02 g / cm 3 .
Also, when the fibers are put in a container, in order to increase the processing efficiency, the fibers can be compressed to have a bulk density of 0.02 g / cm 3 or more using a pressure plate or the like, or can be heat-treated while being compressed.
【００２９】このようにしてホウ素化合物を添加し、か
つ嵩密度を高めた繊維は次に熱処理する。窒化ホウ素で
ＶＧＣＦ表面を被覆するための熱処理温度は、２０００
〜３０００℃、好ましくは２０００〜２５００℃が必要
である。処理温度が低いと窒化ホウ素が生成せず、ま
た、ＶＧＣＦの黒鉛結晶の発達が不十分となる。The fiber to which the boron compound has been added and the bulk density has been increased is then heat-treated. The heat treatment temperature for coating the VGCF surface with boron nitride is 2000
~ 3000C, preferably 2000-2500C. If the treatment temperature is low, boron nitride is not generated, and the development of graphite crystals of VGCF becomes insufficient.
【００３０】熱処理方法は、通常の抵抗加熱炉、高周波
炉やアチソン炉等の黒鉛化炉を用いることができる。熱
処理温度までの昇温時間は、ホウ素化合物の分解による
ホウ素生成、ホウ素の拡散が起こるため、短い方が好ま
しい。また、ホウ素の拡散をしやすくするために、ホウ
素化合物とＶＧＣＦとの混合物を黒鉛ルツボ等の容器に
入れて熱処理することもできる。ホウ素化合物との熱処
理をする前の気相法炭素繊維としては、製造後繊維表面
に付着するタール等熱分解物の除去のための熱処理を行
う前の熱分解ＣＦそのもの、これを約８００〜１５００
℃でアルゴン等の不活性ガス中で熱処理を行ったもの、
また炭素構造の結晶性を向上させるために約２０００〜
３０００℃で黒鉛化を行った後のＶＧＣＦのいずれでも
用いることができる。As the heat treatment method, an ordinary resistance heating furnace, a graphitization furnace such as a high frequency furnace or an Acheson furnace can be used. It is preferable that the heating time up to the heat treatment temperature is short because boron is generated and boron is diffused by decomposition of the boron compound. In order to facilitate the diffusion of boron, a mixture of a boron compound and VGCF can be placed in a container such as a graphite crucible and heat-treated. As the vapor grown carbon fiber before the heat treatment with the boron compound, the thermally decomposed CF itself before the heat treatment for removing the thermally decomposed product such as tar adhering to the fiber surface after production, which is about 800 to 1500
Heat-treated in an inert gas such as argon at ℃
In addition, about 2000 to improve the crystallinity of the carbon structure
Any of the VGCFs after graphitization at 3000 ° C. can be used.
【００３１】熱処理時の窒素雰囲気は、例えば、黒鉛円
筒を発熱体とする高周波加熱炉では、窒素雰囲気が保持
できれば良い。本発明で「被覆」とは、ＶＧＣＦ表面に
おいて少なくとも一部に窒化ホウ素が存在していれば良
く、好ましくは、全表面の７０％以上、より好ましくは
８０％以上存在しており、均一でも不均一でも良く、密
度としては密でも粗でもよいが部分的よりは全体的に窒
化ホウ素が存在するのがよい。表面から１ｎｍ程度の深
さにおいてＸ−線光電子分析法により表面のホウ素含有
量が１０質量％以上、好ましくは２０質量％、より好ま
しくは３０質量％以上、これをＶＧＣＦ全体での含有量
とすると窒化ホウ素で２質量％以上あればよい。また、
ＢあるいはＮはＶＧＣＦ表面ばかりでなく、ＶＧＣＦ内
部に存在してもよい。As the nitrogen atmosphere during the heat treatment, for example, in a high-frequency heating furnace using a graphite cylinder as a heating element, it is sufficient that the nitrogen atmosphere can be maintained. In the present invention, “coating” means that boron nitride is present on at least a part of the surface of the VGCF, preferably 70% or more, more preferably 80% or more of the entire surface. The density may be uniform and the density may be dense or coarse, but it is preferable that boron nitride is present entirely rather than partially. At a depth of about 1 nm from the surface, by X-ray photoelectron analysis, the boron content of the surface is 10% by mass or more, preferably 20% by mass, more preferably 30% by mass or more. It is sufficient that the content of boron nitride is 2% by mass or more. Also,
B or N may exist not only on the VGCF surface but also inside the VGCF.
【００３２】本発明の窒化ホウ素で被覆されたＶＧＣＦ
の電気絶縁性は、その比抵抗で評価できる。比抵抗の測
定方法は、被覆ＶＧＣＦは粉体状であるため、それを嵩
密度０．８ｇ／ｃｍ3に圧密したときの粉体の比抵抗を
測定している。本発明の被覆ＶＧＣＦの比抵抗は１０3
Ω・ｃｍ以上、好ましくは１０5Ω・ｃｍ以上、さらに
好ましくは１０6Ω・ｃｍ以上である。また、本発明の
窒化ホウ素で被覆されたＶＧＣＦの熱伝導率は、不純物
や空孔率などに大きく影響されるが、室温で１５０Ｗｍ
-1Ｋ-1（１５０Ｊｍ-1ｓ-1Ｋ-1）以上が好ましい。VGCF coated with boron nitride of the present invention
Can be evaluated by its specific resistance. The specific resistance is measured by measuring the specific resistance of the powder when the coated VGCF is compacted to a bulk density of 0.8 g / cm 3 because the coated VGCF is in a powder form. The specific resistance of the coated VGCF of the present invention is 10 3
Ω · cm or more, preferably 10 5 Ω · cm or more, more preferably 10 6 Ω · cm or more. Further, the thermal conductivity of the VGCF coated with boron nitride of the present invention is greatly affected by impurities, porosity and the like.
-1 K -1 (150 Jm -1 s -1 K -1 ) or more is preferable.
【００３３】本発明のＶＧＣＦは炭素繊維の結晶性を向
上させたものであり、さらに被覆されている窒化ホウ素
も熱伝導性が良いが、熱伝導性はＶＧＣＦの結晶性が支
配的であるので、その熱導電性は炭素の黒鉛構造の指標
であるＣｏで評価することができ、そのＣｏ値は０．６
８０ｎｍ以下が好ましい。Ｃｏがこれより大きいと良好
な熱伝導性が得られない。合成樹脂に本発明の炭素繊維
を含めて、電気絶縁性複合材とする場合は合成樹脂とし
て、プラスチック、合成ゴムなどを用いることができ
る。また、プラスチックなどに本発明の窒化ホウ素被覆
ＶＧＣＦを放熱フィラーとして用いた場合は該ＶＧＣＦ
の含有量により材料の熱伝導率は変化するが、材料の熱
伝導率はＪＩＳ Ａ−１４１２の平板比較法、円筒法、
平板直接法やレーザーフラッシュ法などの非定常法で測
定できる。本発明により、熱伝導性が良く、電気絶縁性
の高い被覆ＶＧＣＦを提供することができ、特に電子デ
バイス等の放熱板等の複合材料の放熱フィラーとして極
めて有利に用いることができる。The VGCF of the present invention is obtained by improving the crystallinity of carbon fibers, and the coated boron nitride also has good thermal conductivity, but the thermal conductivity is dominated by the VGCF crystallinity. The thermal conductivity can be evaluated by Co, which is an index of the graphite structure of carbon, and the Co value is 0.6.
80 nm or less is preferable. If Co is larger than this, good thermal conductivity cannot be obtained. In the case where the synthetic resin contains the carbon fiber of the present invention to form an electrically insulating composite material, plastic, synthetic rubber, or the like can be used as the synthetic resin. When the boron nitride-coated VGCF of the present invention is used as a heat-radiating filler in plastics or the like, the VGCF
The thermal conductivity of the material changes depending on the content of, but the thermal conductivity of the material can be determined by the flat plate comparison method, the cylindrical method,
It can be measured by an unsteady method such as a direct plate method or a laser flash method. According to the present invention, a coated VGCF having good thermal conductivity and high electrical insulation can be provided, and can be used extremely advantageously as a heat-radiating filler of a composite material such as a heat-radiating plate of an electronic device.
【００３４】[0034]
【実施例】以下に、本発明の実施例を説明する。 （実施例１）特許２７７８４３４号に開示された方法で
繊維径０．１〜０．２μｍ、アスペクト比２０〜５００
程度の熱分解ＣＦを製造した。この熱分解ＣＦを黒鉛ル
ツボに詰めてアルゴン雰囲気下１２００℃×２０分の熱
処理を行った。この熱処理ＣＦを取り出し、Ｂ4Ｃ（和
光純薬製）を１０質量％添加し混合して、再度黒鉛ルツ
ボに詰め、窒素雰囲気下、約２時間で２４００℃に昇温
し、黒鉛ルツボの中心まで温度が均一になるのに必要な
保持時間として、本実施例の場合は６０分保持し、熱処
理を行った。Embodiments of the present invention will be described below. (Example 1) A fiber diameter of 0.1 to 0.2 µm and an aspect ratio of 20 to 500 according to the method disclosed in Japanese Patent No. 2778434.
A degree of pyrolysis CF was produced. This pyrolytic CF was packed in a graphite crucible and heat-treated at 1200 ° C. for 20 minutes in an argon atmosphere. The heat-treated CF was taken out, B 4 C (manufactured by Wako Pure Chemical Industries) was added at 10% by mass, mixed, packed again in a graphite crucible, heated to 2400 ° C. in a nitrogen atmosphere for about 2 hours, and the center of the graphite crucible was heated. In the case of the present example, the heat treatment was performed by holding for 60 minutes as a holding time required to make the temperature uniform until the heat treatment.
【００３５】熱処理後、後処理として被覆ＶＧＣＦ製造
の際に副生した炭素粒子等を分級操作で除き、これを窒
化ホウ素被覆ＶＧＣＦ試料とした。本試料の評価とし
て、ＶＧＣＦ全量に対するホウ素含有量、比抵抗および
Ｃｏを測定し、その結果を表１に示す。また、本発明の
窒化ホウ素で被覆された気相法炭素繊維の表面のホウ素
と窒素の含有量は、Ｘ線光電子分析法で求め表面から１
ｎｍ程度の深さまでのホウ素含有量及び窒素含有量は、
ホウ素が３９質量％、また窒素が５０質量％であった。After the heat treatment, as a post-treatment, carbon particles and the like by-produced during the production of the coated VGCF were removed by a classification operation to obtain a boron nitride-coated VGCF sample. As an evaluation of this sample, the boron content, specific resistance, and Co with respect to the total amount of VGCF were measured, and the results are shown in Table 1. In addition, the content of boron and nitrogen on the surface of the vapor grown carbon fiber coated with boron nitride of the present invention was determined by X-ray photoelectron analysis to be 1% from the surface.
The boron content and nitrogen content to a depth of about nm are
Boron was 39% by mass and nitrogen was 50% by mass.
【００３６】（実施例２）Ｂ4Ｃの添加量を２０質量％
として、実施例１同様の処理を行い、その評価結果を表
１に示した。Example 2 The amount of B 4 C added was 20% by mass.
The same processing as in Example 1 was performed, and the evaluation results are shown in Table 1.
【００３７】（比較例１）Ｂ4Ｃを添加しないで、実施
例１同様の処理を行い、その評価結果を表１に示した。 （比較例２）実施例１において、窒素雰囲気の代わりに
アルゴン雰囲気下で同様に処理を行い、その結果を表１
に示す。(Comparative Example 1) The same treatment as in Example 1 was performed without adding B 4 C, and the evaluation results are shown in Table 1. (Comparative Example 2) The same treatment as in Example 1 was performed under an argon atmosphere instead of a nitrogen atmosphere.
Shown in
【００３８】[0038]
【表１】 [Table 1]
【００３９】（実施例３）実施例１で得られた窒化ホウ
素被覆ＶＧＣＦを用いて、それを３０質量％含むＰＥＴ
との複合体を調整し、レーザーフラッシュ法で熱伝導率
を測定した。窒化ホウ素被覆ＶＧＣＦ配向方向の室温で
の熱伝導率は４５Ｗｍ-1Ｋ-1であった。(Example 3) PET containing 30% by mass of the boron nitride-coated VGCF obtained in Example 1
Was prepared, and the thermal conductivity was measured by a laser flash method. The thermal conductivity at room temperature in the orientation of the boron nitride-coated VGCF was 45 Wm -1 K -1 .
【００４０】[0040]
【発明の効果】本発明により、熱伝導性が良い、電気絶
縁性のＶＧＣＦを提供することができ、特に電子デバイ
ス等の放熱板等の複合材料の放熱フィラーとして用いる
ことができる。繊維径０．０１〜０．５μｍのＶＧＣＦ
の表面が電気絶縁体、特に、窒化ホウ素で被覆されるこ
とで、該繊維の嵩密度０．８ｇ／ｃｍ3に圧密したとき
の非抵抗が１０3Ω・ｃｍ以上になる。また、該繊維の
室温での熱伝導率が１５０Ｗｍ-1Ｋ-1以上を示し、高い
熱伝導性を有することができる。According to the present invention, an electrically insulating VGCF having good thermal conductivity can be provided, and can be used particularly as a heat-radiating filler for a composite material such as a heat-radiating plate of an electronic device. VGCF with a fiber diameter of 0.01 to 0.5 μm
Is coated with an electrical insulator, particularly boron nitride, so that the fiber has a non-resistance of 10 3 Ω · cm or more when compacted to a bulk density of 0.8 g / cm 3 . In addition, the fiber has a thermal conductivity of 150 Wm -1 K -1 or more at room temperature, and can have high thermal conductivity.
フロントページの続き (72)発明者 山本 竜之 神奈川県川崎市川崎区大川町５−１ 昭和 電工株式会社生産技術センター内 Ｆターム(参考） 4J002 AA001 AC001 DA016 DE077 DE097 DE147 DF017 DJ007 DJ017 DJ057 DK007 FA046 FB076 GQ00 4L031 AA27 AB01 BA21 CB13 4L037 CS03 CS31 CS38 FA02 FA03 FA19 PA01 PA36 UA03 UA06Continued on the front page (72) Inventor Tatsuyuki Yamamoto 5-1 Okawacho, Kawasaki-ku, Kawasaki-shi, Kanagawa F-term in the Showa Denko KK Production Technology Center (Reference) 4J002 AA001 AC001 DA016 DE077 DE097 DE147 DF017 DJ007 DJ017 DJ057 DK007 FA046 FB076 GQ00 4L031 AA27 AB01 BA21 CB13 4L037 CS03 CS31 CS38 FA02 FA03 FA19 PA01 PA36 UA03 UA06
Claims (14)
素繊維の表面の一部または全部が電気絶縁体で被覆され
た電気絶縁体被覆気相法炭素繊維。An electric insulator coated vapor grown carbon fiber in which a part or all of the surface of a vapor grown carbon fiber having a fiber diameter of 0.01 to 0.5 μm is coated with an electric insulator.
徴とする請求項１に記載の電気絶縁体被覆気相法炭素繊
維。2. The vapor-grown carbon fiber coated with an electrical insulator according to claim 1, wherein the electrical insulator is boron nitride.
素含有量が２質量％以上、Ｃ０が０．６８０ｎｍ以下で
ある請求項２に記載の電気絶縁体被覆気相法炭素繊維。3. The electric insulator-coated vapor-grown carbon fiber according to claim 2, wherein the boron nitride content is 2% by mass or more and C0 is 0.680 nm or less based on the total amount of the vapor-grown carbon fiber.
におけるホウ素含有量が１０質量％以上であることを特
徴とする請求項２または３に記載の電気絶縁体被覆気相
法炭素繊維。4. The vapor-grown carbon fiber coated with an electrical insulator according to claim 2, wherein the boron content at a depth of 1 nm from the surface of the vapor-grown carbon fiber is 10% by mass or more. .
比抵抗が１０3Ω・ｃｍ以上、熱伝導率が１５０Ｗｍ-1
Ｋ-1以上の請求項１〜４のいずれか１項に記載の電気絶
縁体被覆気相法炭素繊維。5. A material having a specific resistance of 10 3 Ω · cm or more and a thermal conductivity of 150 Wm −1 when compacted to a bulk density of 0.8 g / cm 3.
The vapor-grown carbon fiber coated with an electric insulator according to any one of claims 1 to 4, which has a K -1 or more.
素繊維とホウ素化合物を混合し、窒素化合物存在下、２
０００℃以上で熱処理を行うことを特徴とする電気絶縁
体被覆気相法炭素繊維の製造方法。6. A vapor-grown carbon fiber having a fiber diameter of 0.01 to 0.5 μm is mixed with a boron compound,
A method for producing a vapor-grown carbon fiber coated with an electric insulator, wherein the heat treatment is performed at 000 ° C. or higher.
素繊維とホウ素化合物を混合し、該混合物を圧縮し、窒
素化合物存在下、２０００℃以上で熱処理を行う窒化ホ
ウ素で被覆された電気絶縁体被覆気相法炭素繊維の製造
方法。7. A vapor-grown carbon fiber having a fiber diameter of 0.01 to 0.5 μm and a boron compound are mixed, the mixture is compressed, and the mixture is coated with boron nitride which is heat-treated at 2000 ° C. or more in the presence of a nitrogen compound. Of producing a vapor-grown carbon fiber coated with an electrical insulator.
る請求項６または７に記載の電気絶縁体被覆気相法炭素
繊維の製造方法。8. The method for producing a vapor-grown carbon fiber coated with an electric insulator according to claim 6, wherein the nitrogen compound is nitrogen.
ホウ酸塩、酸化ホウ素、Ｂ4Ｃおよび窒化ホウ素からな
る群から選ばれた少なくとも１種である請求項６〜８の
いずれか１項に記載の電気絶縁体被覆気相法炭素繊維の
製造方法。9. The method according to claim 9, wherein the boron compound is elemental boron, boric acid,
Borate, boron oxide, B 4 C and a manufacturing method of an electrical insulator coating vapor grown carbon fiber according to any one of claims 6 to 8 is at least one selected from the group consisting of boron nitride .
合物のホウ素濃度が、ホウ素元素として１質量％以上、
３０質量％以下であることを特徴とする請求項６〜９の
いずれか１項に記載の電気絶縁体被覆気相法炭素繊維の
製造方法。10. The mixture of a boron compound and a vapor grown carbon fiber has a boron concentration of 1% by mass or more as a boron element.
The method for producing a vapor-grown carbon fiber coated with an electric insulator according to any one of claims 6 to 9, wherein the content is 30% by mass or less.
炭素繊維の表面の一部または全部が電気絶縁体で被覆さ
れた電気絶縁体被覆気相法炭素繊維を含む合成樹脂また
は合成ゴム組成物からなる電気絶縁性複合材。11. Synthetic resin or synthetic resin containing vapor-grown carbon fiber coated with an electric insulator, wherein a part or all of the surface of vapor-grown carbon fiber having a fiber diameter of 0.01 to 0.5 μm is coated with an electric insulator. An electrically insulating composite material comprising a rubber composition.
１１に記載の電気絶縁性複合材。12. The electrically insulating composite according to claim 11, wherein the electrical insulator is boron nitride.
電気絶縁体被覆気相法炭素繊維を含む合成樹脂または合
成ゴム組成物からなる電気絶縁性複合材。13. An electrically insulating composite material comprising a synthetic resin or a synthetic rubber composition containing the electric insulator-coated vapor-grown carbon fiber according to any one of claims 3 to 5.
電気絶縁体被覆気相法炭素繊維を含む放熱材料。14. A heat-dissipating material containing the vapor-grown carbon fiber coated with an electric insulator according to claim 1. Description:
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