JP2005093114A - Field electron emission structure and its manufacturing method - Google Patents
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Abstract
Description
本発明は電界電子放出体およびその製造方法に関する。 The present invention relates to a field electron emitter and a manufacturing method thereof.
カーボンナノチューブ（ＣＮＴ）からの電界放出（field emission）が検討され、ディスプレー用材料としての有用性に注目されている。
１本のＣＮＴから放出される電流には限界があるが、多数のＣＮＴを用いれば、大きな電流を得ることができる。
このため、電界電子放出体として、樹脂で固めたＭＷＣＮＴ（マルチウォールＣＮＴ）膜やＳＷＣＮＴ（シングルウォールＣＮＴ）膜が研究されている。
Although there is a limit to the current emitted from one CNT, a large current can be obtained by using a large number of CNTs.
For this reason, MWCNT (multiwall CNT) films and SWCNT (single wall CNT) films hardened with resin have been studied as field electron emitters.
例えば気相成長法によるカーボンナノチューブ（昭和電工製ＶＧＣＦ）は直径が数十ｎｍ、長さが数μｍ程度のアスペクト比が大きく、細長い炭素繊維であり、その鋭いエッジ部から電界電子が放出される。しかしながら、ＣＮＴを樹脂で固めた場合には、ＣＮＴが樹脂中に埋没し、エッジ部が露出しないことから、電界電子放出特性が抑制されるという課題がある。 For example, carbon nanotubes produced by vapor deposition (VGCF manufactured by Showa Denko) are elongated carbon fibers having a large aspect ratio of several tens of nm in diameter and several μm in length, and field electrons are emitted from the sharp edges. . However, when the CNTs are hardened with a resin, the CNTs are buried in the resin and the edge portions are not exposed, so that there is a problem that field electron emission characteristics are suppressed.
そこで本発明は上記課題を解決すべくなされたもので、その目的とするところは、良好な電界電子放出特性が得られる電界電子放出体とその製造方法を提供するにある。 Accordingly, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a field electron emitter capable of obtaining good field electron emission characteristics and a method for manufacturing the same.
本発明に係る電界電子放出体は、樹脂材料中にカーボンナノチューブが配合され、酸化性雰囲気中で加熱処理されることにより、樹脂材料が炭化してカーボンナノチューブ端部が露出すると共に、カーボンナノチューブが炭化した樹脂により固着していることを特徴とする。
また、一方の面に電極が固定されていることを特徴とする。
電極は導電性接着剤により固定することができる。
また、カーボンナノチューブが気相成長法による炭素繊維であることを特徴とする。
In the field electron emitter according to the present invention, carbon nanotubes are blended in a resin material and heat-treated in an oxidizing atmosphere, so that the resin material is carbonized to expose the end portions of the carbon nanotubes. It is characterized by being fixed by a carbonized resin.
Further, an electrode is fixed to one surface.
The electrode can be fixed with a conductive adhesive.
Further, the carbon nanotube is a carbon fiber formed by a vapor phase growth method.
本発明に係る電界電子放出体の製造方法では、樹脂材料中にカーボンナノチューブを配合する工程と、該混合材料を酸化性雰囲気中で加熱処理して、樹脂材料を炭化させると共に、該炭化した樹脂によりカーボンナノチューブを固着する加熱処理工程とを含むことを特徴とする。
前記混合材料を所要形状に成形し、この成形物を酸化性雰囲気中で加熱処理することができる。
あるいは前記混合材料を所要支持体上に塗布した状態で加熱処理することができる。
樹脂材料に対するカーボンナノチューブの配合量を２０ｗｔ％以下にするとよい。
加熱処理は誘導加熱により行うと好適である。
In the method for producing a field electron emitter according to the present invention, the step of compounding carbon nanotubes in a resin material, the mixed material is heat-treated in an oxidizing atmosphere to carbonize the resin material, and the carbonized resin And a heat treatment step for fixing the carbon nanotubes.
The mixed material can be molded into a required shape, and the molded product can be heat-treated in an oxidizing atmosphere.
Or it can heat-process in the state which apply | coated the said mixed material on the required support body.
The compounding amount of the carbon nanotube with respect to the resin material is preferably 20 wt% or less.
The heat treatment is preferably performed by induction heating.
以上のように、本発明によれば、樹脂材料とＣＮＴとを混合し、加熱処理して樹脂材料を炭化するので、ＣＮＴのエッジ部を露出させることができ、電界電子放出特性に優れる電界電子放出体を提供できる。また、任意の形状、大きさに形成できるので、特に大面積の冷陰極の作成が可能となる。 As described above, according to the present invention, since the resin material and CNT are mixed and heat-treated to carbonize the resin material, the edge portion of the CNT can be exposed, and the field electrons having excellent field electron emission characteristics. An emitter can be provided. Moreover, since it can be formed in an arbitrary shape and size, a cold cathode having a particularly large area can be produced.
以下、本発明の好適な実施の形態を添付図面に基づいて詳細に説明する。
本実施の形態における電界電子放出体は、前記のように、樹脂材料中にカーボンナノチューブが配合され、加熱処理されることにより、樹脂材料が炭化するとともに雰囲気中の酸素によって一部酸化されることによって、カーボンナノチューブが露出し、ナノチューブ自体も側面が局部的に酸化されて、電子を放出しやすいエッジ面がでる。カーボンナノチューブは炭化した樹脂により固着している。
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
As described above, in the field electron emitter in the present embodiment, carbon nanotubes are blended in a resin material and heat-treated, whereby the resin material is carbonized and partially oxidized by oxygen in the atmosphere. As a result, the carbon nanotubes are exposed, and the side surfaces of the nanotubes themselves are locally oxidized to form an edge surface that is easy to emit electrons. The carbon nanotubes are fixed by carbonized resin.
樹脂材料は特に限定されるものではなく、ポリエチレン樹脂、ポリプロピレン樹脂等の、加熱処理により炭化する樹脂であればよい。
また、カーボンナノチューブも特に限定されないが、大量に入手しうるものとして気相成長法による炭素繊維、例えば昭和電工製ＶＧＣＦなどを好適に用いることができる。
なお、電界電子放出特性としては、エッジ部がより尖鋭であるＳＷＣＮＴの方がＭＷＣＮＴよりも優れている。
The resin material is not particularly limited as long as it is a resin that is carbonized by heat treatment, such as polyethylene resin or polypropylene resin.
Carbon nanotubes are not particularly limited, but carbon fibers obtained by vapor phase growth, such as VGCF manufactured by Showa Denko, can be suitably used as those that can be obtained in large quantities.
As field electron emission characteristics, SWCNTs with sharper edges are superior to MWCNTs.
カーボンナノチューブ（ＣＮＴ）と樹脂との複合材およびその成形物は例えば次のようにして作ることができる。
１）樹脂材料とＣＮＴを溶媒中に分散させる。この場合には、例えば混合物に超音波エネルギーを付与することによりＣＮＴを樹脂中に均一に分散させるようにする。
ＣＮＴの樹脂材料に対する配合比率は２０ｗｔ％以下が好適である。
次いで、混合物を加熱して溶媒を揮散させ、さらに粗砕することによって、ＣＮＴが混入された樹脂ペレットを得る。
この樹脂ペレットを用いてインジェクション成形して、任意大きさの板状（フイルム状を含む）の成形体をつくる。
ＣＮＴを直接熱可塑性樹脂中に練り込むようにすることもできる。この場合には２軸押出し装置等を用いて混合し、ペレット状にする。
２）溶媒に分散した樹脂材料とＣＮＴの混合物を適宜な支持体（例えば金属板）上に塗布して板状の成形体としてもよい。
A composite material of carbon nanotubes (CNT) and a resin and a molded product thereof can be produced, for example, as follows.
1) A resin material and CNT are dispersed in a solvent. In this case, for example, by applying ultrasonic energy to the mixture, the CNTs are uniformly dispersed in the resin.
The mixing ratio of CNT to the resin material is preferably 20 wt% or less.
Next, the mixture is heated to volatilize the solvent, and further crushed to obtain resin pellets mixed with CNTs.
This resin pellet is used for injection molding to produce a plate-shaped (including film-shaped) molded body having an arbitrary size.
It is also possible to knead CNT directly into a thermoplastic resin. In this case, the mixture is mixed using a twin screw extruder or the like to form a pellet.
2) A mixture of a resin material dispersed in a solvent and CNTs may be applied onto an appropriate support (for example, a metal plate) to form a plate-like molded body.
上記成形体を加熱処理して樹脂材料を炭化させるのである。
加熱処理は成形体を大気雰囲気下で誘導加熱により行うと好適である。
ディスプレイの冷陰極として用いる場合には、上記の加熱処理物の一方の面に導電性接着剤等により電極を固定するようにする。
導電性接着剤としては、金属粉または炭素粉をフィラーとして混入する接着性を有する樹脂を用いることができる。
The molded body is heat-treated to carbonize the resin material.
The heat treatment is preferably performed by induction heating of the molded body in an air atmosphere.
When used as a cold cathode of a display, an electrode is fixed to one surface of the heat-treated product with a conductive adhesive or the like.
As the conductive adhesive, it is possible to use an adhesive resin in which metal powder or carbon powder is mixed as a filler.
樹脂材料（ポリプロピレン）中に気相成長法炭素繊維（昭和電工製ＶＧＣＦ）１０ｗｔ％を均一に混合した複合材料からなる樹脂ペレットを用いて、インジェクションにより板状の成形体を形成した。
この成形体を誘導加熱装置に収容し、大気雰囲気下で約７００℃、１０分間加熱して、樹脂材料を加熱（炭化）処理した。
A plate-like molded body was formed by injection using resin pellets made of a composite material in which 10 wt% of vapor grown carbon fiber (VGCF manufactured by Showa Denko) was uniformly mixed in a resin material (polypropylene).
This molded body was accommodated in an induction heating apparatus and heated at about 700 ° C. for 10 minutes in an air atmosphere to heat (carbonize) the resin material.
加熱処理前の成形体の表面、および上記加熱処理した成形体（加熱処理物）の表面の走査型電子顕微鏡写真を図１、図２、図３（図３は図２の拡大図）に示す。
図１に示すように、加熱処理前にあってはＣＮＴが成形体中に埋没し、その表面にはほとんど現れていない。上記加熱処理を行うと、図２、図３に示すように、樹脂材料が炭化し、この非晶質炭素間に固着されたＣＮＴが露出するようになる。
すなわち、ＣＮＴのエッジ部が露出し（図３）、良好な電界電子放出特性が得られるようになる。
Scanning electron micrographs of the surface of the molded body before heat treatment and the surface of the heat-treated molded body (heat-treated product) are shown in FIGS. 1, 2, and 3 (FIG. 3 is an enlarged view of FIG. 2). .
As shown in FIG. 1, before the heat treatment, CNTs are buried in the molded body and hardly appear on the surface. When the heat treatment is performed, as shown in FIGS. 2 and 3, the resin material is carbonized, and the CNTs fixed between the amorphous carbons are exposed.
That is, the edge portion of the CNT is exposed (FIG. 3), and good field electron emission characteristics can be obtained.
図４に電界電子放出特性の測定結果を示す。この測定は、１０-4Ｐａの真空中で、電界を印加して流れる電流を測定することにより評価した。電極間距離はマイクロメータヘッドで制御し、約６００μｍとした。電流は指針微小形電流計で測定した。
図４に示されるように、１×１０-6Ａ／ｃｍ2の電流が流れる電界を閾値と考えると、閾値電界はおよそ２．５Ｖ／μｍとなっている。電界電圧が３．３Ｖ／μｍのとき、約３．８×１０-6Ａ／ｃｍ2の電流が流れた。電流は単調に増加しており、さらに高い電圧を加えることにより大きな電流が得られると考えられる。
用いたＶＧＣＦはＭＷＣＮＴである。ＳＷＣＮＴやＷＷＣＮＴも用いることが可能であり、さらに低い閾値電圧が得られると考えられる。
FIG. 4 shows the measurement results of the field electron emission characteristics. This measurement was evaluated by measuring a flowing current by applying an electric field in a vacuum of 10 −4 Pa. The distance between the electrodes was controlled by a micrometer head, and was about 600 μm. The current was measured with a pointer micro-type ammeter.
As shown in FIG. 4, when the electric field through which a current of 1 × 10 −6 A / cm 2 flows is considered as a threshold value, the threshold electric field is approximately 2.5 V / μm. When the electric field voltage was 3.3 V / μm, a current of about 3.8 × 10 −6 A / cm 2 flowed. The current increases monotonously, and it is considered that a large current can be obtained by applying a higher voltage.
The VGCF used is MWCNT. SWCNT and WWCNT can also be used, and it is considered that a lower threshold voltage can be obtained.
本実施例における閾値電圧は、これまでに報告されている最小の値よりも低いとは言えないが、ほぼ同程度の値が得られている。
本実施例では、成形体を、射出成形等で成形して形成するほか、ＣＮＴをエポキシ樹脂等の熱硬化性樹脂と混合してペースト状にし、支持体上に塗布して、任意の形状、かつ大きな板状（フイルム状を含む）に形成できるので、大面積の電界電子放出体が得られるのであり、実用的価値は高い。
Although it cannot be said that the threshold voltage in the present embodiment is lower than the minimum value reported so far, almost the same value is obtained.
In this example, the molded body is formed by injection molding or the like, and CNT is mixed with a thermosetting resin such as an epoxy resin to form a paste, which is applied onto the support, In addition, since it can be formed into a large plate shape (including a film shape), a large-area field electron emitter can be obtained, and its practical value is high.
Claims (10)
該混合材料を酸化性雰囲気中で加熱処理して、樹脂材料を炭化させると共に、該炭化した樹脂によりカーボンナノチューブを固着する加熱処理工程とを含むことを特徴とする電界電子放出体の製造方法。 Blending carbon nanotubes into the resin material;
A method of manufacturing a field electron emitter, comprising: heat-treating the mixed material in an oxidizing atmosphere to carbonize the resin material and fixing the carbon nanotubes with the carbonized resin.
The method of manufacturing a field electron emitter according to any one of claims 5 to 9, further comprising a step of fixing an electrode to the one surface of the heat-treated product with a conductive adhesive.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100854540B1 (en) | 2007-01-30 | 2008-08-26 | 재단법인서울대학교산학협력재단 | Carbon nanotubes complex and the process of manufacturing thereof |
| JP2008226734A (en) * | 2007-03-14 | 2008-09-25 | Showa Denko Kk | Composition for forming thin film type electron emission material, thin film type electron emission material, its manufacturing method, and field emission type element |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100854540B1 (en) | 2007-01-30 | 2008-08-26 | 재단법인서울대학교산학협력재단 | Carbon nanotubes complex and the process of manufacturing thereof |
| JP2008226734A (en) * | 2007-03-14 | 2008-09-25 | Showa Denko Kk | Composition for forming thin film type electron emission material, thin film type electron emission material, its manufacturing method, and field emission type element |
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