JP3978653B2 - Thin wire cord - Google Patents

Description

【００１３】
実質的にＰＢＯから成るポリマーのドープを形成するための好適溶媒としては、クレゾールやそのポリマーを溶解し得る非酸化性の酸が含まれる。好適な酸溶媒の例としては、ポリ燐酸、メタンスルフォン酸及び高濃度の硫酸或いはそれ等の混合物があげられる。更に適する溶媒は、ポリ燐酸及びメタンスルフォン酸である。また最も適する溶媒は、ポリ燐酸である。
【００１４】
溶媒中のポリマー濃度は好ましくは少なくとも約７重量%であり、更に好ましくは少なくとも１０重量%、最も好ましくは１４重量%である。最大濃度は、例えばポリマーの溶解性やドープ粘度といった実際上の取り扱い性により限定される。それらの限界要因のために、ポリマー濃度は２０重量%を越えることはない。
【００１５】
好適なポリマーやコポリマーあるいはドープは公知の手法により合成される。例えばWolfe等の米国特許第4533693号（１９８５年８月６日）、Sybert等の米国特許第4772678号（１９８８年９月２０日）、Harrisの米国特許第4847350号（１９８９年７月１１日）に記載される方法で合成される。実質的にＰＢＯから成るポリマーはGregory等の米国特許第5089591号（１９９２年２月１８日）によると、脱水性の酸溶媒中での比較的高温、高剪断条件下において高い反応速度での高分子量化が可能である。
【００１６】
添加するカーボンナノチューブはドープを合成するときにドープ原料と同時に配合しておく。良好な電気物性を発現せしめるためには、カーボンナノチューブがドープ中に均一に混合分散している必要がある。この目的のためには、ドープを重合する前に原料を投入した後８０℃以下の温度にて一旦原料同士を攪拌混合した後定法に従ってドープを調製すると良い。添加量はモノマー仕込量に対して重量分率にして１％以上６０％未満、好ましくは２％以上５０％未満である。この量より少ないと完成糸中に含有されるカーボンナノチューブが少なくなり電気伝導性の発現が期待できない。反対に多すぎるとカーボンナノチューブの繊維中での分散製が悪くなり、完成糸の繊維強度が低下するため好ましくない。
【００１７】
この様にして重合されるドープは紡糸部に供給され、紡糸口金から通常１００℃以上の温度で吐出される。口金細孔の配列は通常円周状、格子状に複数個配列されるが、その他の配列であっても良い。口金細孔数は特に限定されないが、紡糸口金面における紡糸細孔の配列は、吐出糸条間の融着などが発生しないような孔密度を保つことが肝要である。
【００１８】
紡出糸条は十分な延伸比（ＳＤＲ）を得るため、米国特許第5296185号に記載されたように十分な長さのドローゾーン長が必要で、かつ比較的高温度（ドープの固化温度以上で紡糸温度以下）の整流された冷却風で均一に冷却されることが望ましい。ドローゾーンの長さ（Ｌ）は非凝固性の気体中で固化が完了する長さが要求され、大雑把には単孔吐出量（Ｑ）によって決定される。良好な繊維物性を得るにはドローゾーンの取り出し応力がポリマー換算で（ポリマーのみに応力がかかるとして）２ｇ／ｄ以上が望ましい。
【００１９】
ドローゾーンで延伸された糸条は次に抽出（凝固）浴に導かれる。紡糸張力が高いため、抽出浴の乱れなどに対する配慮は必要でなく如何なる形式の抽出浴でも良い。例えばファンネル型、水槽型、アスピレータ型あるいは滝型などが使用出来る。抽出液は燐酸水溶液や水が望ましい。最終的に抽出浴において糸条が含有する燐酸を99.0%以上、好ましくは99.5%以上抽出する。本発明における抽出媒体として用いられる液体に特に限定はないが好ましくはポリベンザゾールに対して実質的に相溶性を有しない水、メタノール、エタノール、アセトン、エチレングリコール等である。また抽出（凝固）浴を多段に分離し燐酸水溶液の濃度を順次薄くし最終的に水で水洗しても良い。さらに該繊維束を水酸化ナトリウム水溶液などで中和し、水洗することが望ましい。この後乾燥、焼成を施して繊維を製造する。
【００２０】
乾燥方法は、オーブンを用いたオフライン乾燥、ローラー乾燥など任意に方法を用いればよい。乾燥温度も６０℃以上５００℃未満、好ましくは７０℃以上４００℃未満である。乾燥の後焼成工程を通してポリマー成分を炭素化する。焼成工程は不活性ガス中で該繊維を蒸し焼きにするのである。不活性ガスの例としてはアルゴン、窒素、ヘリウムなどが上げられる。焼成温度は７００℃以上２０００℃未満、好ましくは７５０℃以上１７００℃未満である。温度が低いと炭素化率が低くなり好ましくない。温度が高すぎると繊維強度の低下を招き好ましくない。
【００２１】
出来あがった導体に周りを樹脂で被覆して細径電線コードを完成する。好適な被覆材としては軽くてフレキシブルなものが良く、一般には柔軟な高分子材料が選ばれる。そのなかでも、特に、ポリイミドやポリパラフェニレンテレフタルアミド、ポリベンザゾールが適している。
【００２２】
＜配向パラメーターの測定方法＞
以下、電子線回折の測定法並びに結晶配向パラメーター＜ｓｉｎ²φ＞の評価法を詳述する。芯線をエポキシ樹脂に包埋したものをダイアモンドナイフ（例えばDiatome）を用いて電子顕微鏡観察用の超薄切片を作製した。作製した切片をメッシュ上に回収し、電子顕微鏡を用いて電子線回折像を撮影した。用いる電子顕微鏡としては例えば日本電子JEM-2010を加速電圧２００kVにて運転すればよい。回折像の記録はフジ写真フィルム（株）製イメージングプレート（ＦＤＬ ＵＲ―Ｖ）を用いて実施した。さらに、フジ写真フィルム（株）製デジタルミクログラフィー（ＦＤＬ５０００）を用いた日本電子（株）製ＰＩＸｓｙｓＴＥＭ２０にて信号強度を読み出した。結晶配向パラメーターは、(002)回折面のデバイ環に沿った方位角方向の回折強度分布からバックグラウンド散乱の補正を施した後数１で定義される式に従って算出した。
【００２３】
【数１】

【００２４】
ここでI(φ)は(002)回折面のデバイ環に沿って測ったバックグラウンド補正後の回折強度の方位角分布、φは方位角方向回折強度プロファイルの極大点を原点として測った方位角である。
【００２５】
（ラマン散乱測定）
ラマン散乱スペクトルは、下記の方法で測定を行った。ラマン測定装置（分光器）はレニショー社のシステム１０００を用いて測定した。光源はヘリウムーネオンレーザー（波長６３３ｎｍ）を用い、偏光方向に繊維軸が平行になるように繊維を設置して測定した。ヤーンから単繊維（モノフィラメント）を分繊し、矩形（縦５０ｍｍ横１０ｍｍ）の穴が空いたボール紙の穴の中心線上に、長軸が繊維軸と一致するように貼り、両端をエポキシ系接着剤（アラルダイト）で止めて２日間以上放置した。その後マイクロメーターで長さが調節できる治具に該繊維を取り付け、単繊維を保持するボール紙を注意深く切り取った後所定の歪みを繊維に与え、該ラマン散乱装置の顕微鏡ステージにのせ、ラマンスペクトルを測定した。このとき、繊維に働く応力をロードセルを用いて同時に測定した。
【００２６】
以下に本発明を実施例を挙げて説明するが勿論本発明はこれらに限定されるものではない。本発明の評価に用いた各尺度は下記の手順で求めた。
【００２７】
＜繊維の繊度＞単糸繊度は温度２０℃、湿度６５ＲＨ％の雰囲気中で２４時間調整した試料につきデニコン［サーチ（株）製］を使用して試料長５０ｍｍ、本数２０で測定を行い、算術平均値を求めた。総繊度は前記条件で調整された試料をラップリールに１０ｍ巻きとって重量を測定し、これを９０００ｍの重量に換算して求めた。
【００２８】
＜繊維束ならびにコードの引張特性＞ＪＩＳ Ｌ−１０１３に準拠してオリエンテック（株）社製テンシロンを用い、つかみ間隔２０ｃｍ、引張速度１００％／ｍｉｎ、ｎ＝１０の測定を行い、パソコン処理によって引張特性を求めた。
【００２９】
＜結節強度の測定方法＞試料のつかみ間隔の中央にＺ撚りの本結びを１個作った状態で、上述の引っ張り強度試験法に準拠して測定して結節強度を評価した。
【００３０】
＜炭素含有量の測定方法＞
炭素含有量は有機元素分析法（例えばヤナコＭＴ−５型 ＣＨＮコーダー）に従って求めた。
【００３１】
電気伝導度の測定は、一般的な測定装置を用いればよい。例えば、ＨＵＳＯ ＥＬＥＣＴＲＯ ＣＨＥＭＩＣＡＬ ＳＹＳＴＥＭ モデル １１１６などを用いればよい。
【００３２】
【実施例】
（実施例１〜４、比較例１〜２）
カーボンナノチューブをポリベンザゾールモノマーと同時に投入して米国特許第4533693号に示される方法によって得られた、３０℃のメタンスルホン酸溶液で測定した固有粘度が24.4dL/gのポリパラフェニレンベンゾビスオキサゾール14.0（重量）%と五酸化リン含有率83.17%のポリ燐酸から成る紡糸ドープを紡糸に用いた。ドープは金属網状の濾材を通過させ、次いで２軸から成る混練り装置で混練りと脱泡を行った後、昇圧させ、重合体溶液温度を１７０℃に保ち、孔数３３を有する紡糸口金から１７０℃で紡出し、温度６０℃の冷却風を用いて吐出糸条を冷却した後、ゴゼットロールに巻き付け紡糸条速度を与え、温度を２０±２℃に保った２０%の燐酸水溶液から成る抽出（凝固）浴中に導入した。引き続いて第２の抽出浴中でイオン交換水で糸条を洗浄した後、0.1規定の水酸化ナトリウム溶液中に浸せきし。中和処理を施した。更に水洗浴で水洗した後、巻き取り、８０℃の乾燥オーブン中で乾燥した。さらに所定の焼成温度に熱した電気炉中で窒素雰囲気下にて焼成した。この様にして製造した芯線にポリイミド原液を塗布した後２５０℃にて重合反応を芯線の表面で進行させることにより被覆を施した。最後に該複合導線にポリ塩化ビニル樹脂（ＰＶＣ）被覆を施してイヤホーンコードを作成した。得られたイヤホーンコードにつきハンダ付け性、コード径等を評価した。評価結果を表１に示した。
【００３３】
【表１】

【００３４】
（比較例３）
カーボンナノチューブ／ポリカーボネート／トルエン（配合重量比＝10/40/50）を良く攪拌して紡糸口金から押し出した後１００度のオーブン中で溶媒を乾燥させて繊維を得た。さらに窒素気流下で１０００℃に加熱して焼成した。コードを実施例１と同じ方法で作成した。結果を表１に示す。
【００３５】
【発明の効果】
ポリベンザゾール繊維を細径電線コードのテンションメンバーに用いることで、強度に優れたコードを得ることが出来た。特に屈曲性（結節強度）に優れていることで今後の回路の高集積化、複雑化に資する。さらに、細繊度且つ高強度の繊維を用いることでハンダ付け性が改善できる。高強度を有することから電線コードのより高度な細径化の要求に対応できる。以上の様に従来ない細径で且つ高強力の電線コードを工業的に効率よく製造することでき、産業界に寄与すること大である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automobile, an electronic device, an audio device, a telephone cord, and an electronic computer represented by a super computer, a personal computer, a telephone exchange, a communication device, a mobile phone, a cardiac pacemaker, a camera, a hearing aid, a video camera, and a micromachine. The present invention relates to electric wire cords used for precision electronic equipment applications. More specifically, the present invention relates to a thin wire cord having a small diameter and high breaking strength.
[0002]
[Prior art]
Although the structure of the electric wire cord is relatively simple, the field of use is wide and the state of use is various, and in order to cope with this, the material constituting the core portion has been studied conventionally. For example, in Japanese Utility Model Laid-Open No. 60-69420, a bending-resistant electric wire in which a metal twisted wire is horizontally wound on a fiber cord such as polyester or Kevlar (aramid fiber: trade name manufactured by DuPont) is used. Japanese Laid-Open Patent Publication No. 2000-228959 proposes a thin wire having aramid fiber as a tension member, a soft copper wire concentrically twisted thereon to form a conductor, and the conductor further covered with a synthetic resin insulator. JP-A-63-175303 and JP-A-1-107415 propose a small-diameter electric wire cord having improved soldering workability using a high-strength polyolefin fiber as a core.
[0003]
[Problems to be solved by the invention]
However, since the thin conductor by the conventional manufacturing method uses a metal, the weight per unit length tends to increase. One of the fields of application of fine-diameter electrical conductors is expected to be used in spacecraft and artificial organ components, and even in ultra-small sensors. In these fields, lightweight and flexibility are required. . Nowadays, due to the demand for weight reduction of circuit boards (copper-clad laminates), a one-dimensional linear cord is not sufficient as a shape, and the appearance of a film-like electrical conductor instead of copper has been expected.
[0004]
[Means for Solving the Problems]
Thus, as a result of intensive studies, the present inventors have reached an invention that solves the above problems by utilizing a core wire substantially made of carbon in which carbon nanotubes are oriented in the fiber axis direction.
[0005]
That is, the present invention has the following configuration.
1. A small-diameter electric wire cord characterized in that a core portion containing carbon nanotubes substantially made of carbon is used as a conductor, and the periphery of the conductor is covered with a thermoplastic resin.
2. The thin wire cord according to the first aspect, wherein the weight fraction of carbon is 90% or more.
3. 2. The thin wire cord according to the first aspect, wherein an orientation parameter of the carbon nanotube is 0.1 or less.
4). 2. The thin wire cord according to the first aspect, wherein the core portion has a Raman scattering peak appearing in a region of 1570-1610 cm ⁻¹ .
5). Core portion, a small diameter according to the first to the half width of the minor peak the least line width of the Raman scattering peak is characterized in that it is of 60cm ^-1 or less present in the region of 1570-1610Cm ^-1 Electric wire cord.
[0006]
The present invention is described in detail below.
As a required characteristic of a thin wire, a flexible material having both electrical conductivity and strength is required as a core material. Therefore, a carbon material containing carbon nanotubes is used as a core material.
[0007]
A carbon nanotube is a tubular compound consisting essentially of carbon, and the number of layers may be either single or multiple. As a production method, an arc discharge method, a vapor phase growth method, and the like are known (Japanese Patent Laid-Open No. 2001-80913). Carbon nanotubes obtained by any method may be used. The outer diameter is 100 nm or less. The length is 0.005 μm or more and 10 μm or less, preferably 1 μm or more and 5 μm or less. If the outer diameter exceeds 50 nm, the flexibility is poor, which is not preferable because the durability against bending fatigue of the finished yarn is deteriorated. If the length exceeds 10 μm, the nanotubes themselves are not oriented in the mechanical stretching direction, which is not preferable. When the length is less than 0.005 μm, the electric conduction performance is not obtained, which is not preferable.
[0008]
In order to develop electric conductivity, it is necessary that the long axis of the carbon nanotube is oriented in the mechanical stretching direction and is uniformly dispersed. Only then will the carbon nanotubes function as electrical conductors. In general, this structure was found for the first time as a result of intensive studies that carbon nanotubes were spontaneously aligned with the orientation of the polymer through normal spinning processes when the carbon nanotubes were uniformly dispersed in the liquid crystal polymer dope. It was.
[0009]
That is, after carbon nanotubes are dispersed in a polymer showing liquid crystal, a conducting wire is produced through spinning, stretching and firing processes. The condition of the liquid crystalline polymer may be that the continuous length of the polymer chain is 1 nm or more and less than 1000 nm, preferably 1.5 nm or more and less than 800 nm, more preferably 2 nm or more and less than 500 nm. Examples of such polymers include polyacrylonitrile, polyparaphenylene terephthalamide, polybenzazole and the like.
[0010]
The polybenzazole in the present invention refers to a PBO homopolymer and a random, sequential or block copolymer with a polybenzazole (PBZ) containing substantially 85% or more of a PBO component. Here, polybenzazole (PBZ) polymer is, for example, Wolf et al., “Liquid Crystalline Polymer Compositions, Process and Products” US Pat. No. 4,703,103 (October 27, 1987), “Liquid Crystalline Polymer Compositions, Process and Products” US Patent No. 4536992 (August 6, 1985), “Liquid Crystalline Poly (2,6-Benzothiazole) Compositions, Process and Products” US Pat. No. 4,533,724 (August 6, 1985), “Liquid Crystalline Polymer Compositions, Process and Products, US Pat. No. 4,453,393 (August 6, 1985), Evers “Thermooxidative-ly Stable Articulated p-Benzobisoxazole and p-Benzobisoxazole Polymers”, US Pat. No. 4,539,567 (November 16, 1982), Tsai “Method for making Heterocyclic Block Copolymer”, US Pat. No. 4578432 (March 25, 1986), and the like.
[0011]
The structural unit contained in the PBZ polymer is preferably selected from lyotropic liquid crystal polymers. The monomer unit consists of monomer units described in structural formulas (a) to (h), and more preferably consists essentially of monomer units selected from structural formulas (a) to (d).
[0012]
[Chemical 1]

[0013]
Suitable solvents for forming a polymer dope consisting essentially of PBO include cresol and a non-oxidizing acid capable of dissolving the polymer. Examples of suitable acid solvents include polyphosphoric acid, methane sulfonic acid and high concentrations of sulfuric acid or mixtures thereof. Further suitable solvents are polyphosphoric acid and methanesulfonic acid. The most suitable solvent is polyphosphoric acid.
[0014]
The polymer concentration in the solvent is preferably at least about 7% by weight, more preferably at least 10% by weight, and most preferably 14% by weight. The maximum concentration is limited by practical handling properties such as polymer solubility and dope viscosity. Due to their limiting factors, the polymer concentration does not exceed 20% by weight.
[0015]
Suitable polymers, copolymers or dopes are synthesized by known techniques. For example, Wolfe et al., US Pat. No. 4,453,393 (August 6, 1985), Sybert et al., US Pat. No. 4,772,678 (September 20, 1988), Harris, US Pat. No. 4,847,350 (July 11, 1989) It is synthesized by the method described in 1. A polymer consisting essentially of PBO, according to Gregory et al., US Pat. No. 5,089,591 (February 18, 1992), has a high reaction rate at high reaction rates under relatively high temperature and high shear conditions in a dehydrating acid solvent. Molecular weight is possible.
[0016]
The carbon nanotube to be added is mixed with the dope raw material when the dope is synthesized. In order to develop good electrical properties, the carbon nanotubes need to be uniformly mixed and dispersed in the dope. For this purpose, the dope is preferably prepared according to a conventional method after stirring the raw materials at a temperature of 80 ° C. or lower after the raw materials are charged before polymerizing the dope. The addition amount is 1% or more and less than 60%, preferably 2% or more and less than 50% in terms of weight fraction with respect to the monomer charge. If the amount is less than this amount, the carbon nanotubes contained in the finished yarn are reduced, and the expression of electrical conductivity cannot be expected. On the other hand, when the amount is too large, the dispersion of carbon nanotubes in the fiber is deteriorated, and the fiber strength of the finished yarn is lowered.
[0017]
The dope polymerized in this way is supplied to the spinning section and discharged from the spinneret at a temperature of usually 100 ° C. or higher. A plurality of base pores are usually arranged in a circumferential shape or a lattice shape, but other arrangements may be used. The number of nozzle holes is not particularly limited, but it is important that the arrangement of the spinning holes on the spinneret surface has a hole density that does not cause fusion between discharged yarns.
[0018]
In order to obtain a sufficient draw ratio (SDR), the spun yarn needs a sufficiently long draw zone length as described in US Pat. No. 5,296,185, and has a relatively high temperature (above the solidification temperature of the dope). It is desirable that the air is uniformly cooled with a rectified cooling air having a temperature equal to or lower than the spinning temperature. The length (L) of the draw zone is required to be a length that completes solidification in a non-solidifying gas, and is roughly determined by the single-hole discharge amount (Q). In order to obtain good fiber properties, it is desirable that the take-out stress of the draw zone is 2 g / d or more in terms of polymer (assuming that only the polymer is stressed).
[0019]
The yarn drawn in the draw zone is then led to an extraction (coagulation) bath. Since the spinning tension is high, it is not necessary to consider the disturbance of the extraction bath, and any type of extraction bath may be used. For example, funnel type, water tank type, aspirator type or waterfall type can be used. The extract is preferably an aqueous phosphoric acid solution or water. Finally, 99.0% or more, preferably 99.5% or more of the phosphoric acid contained in the yarn is extracted in the extraction bath. There are no particular limitations on the liquid used as the extraction medium in the present invention, but water, methanol, ethanol, acetone, ethylene glycol, and the like that are substantially incompatible with polybenzazole are preferred. Further, the extraction (coagulation) bath may be separated into multiple stages, the concentration of the phosphoric acid aqueous solution is gradually reduced, and finally washed with water. Further, the fiber bundle is desirably neutralized with an aqueous sodium hydroxide solution and washed with water. Thereafter, drying and firing are performed to produce a fiber.
[0020]
The drying method may be any method such as off-line drying using an oven or roller drying. The drying temperature is also 60 ° C. or higher and lower than 500 ° C., preferably 70 ° C. or higher and lower than 400 ° C. The polymer component is carbonized through a baking step after drying. In the firing step, the fibers are steamed in an inert gas. Examples of the inert gas include argon, nitrogen, helium and the like. The firing temperature is 700 ° C. or higher and lower than 2000 ° C., preferably 750 ° C. or higher and lower than 1700 ° C. If the temperature is low, the carbonization rate is low, which is not preferable. If the temperature is too high, the fiber strength is lowered, which is not preferable.
[0021]
The finished conductor is covered with resin to complete the thin wire cord. A suitable covering material is light and flexible, and a flexible polymer material is generally selected. Of these, polyimide, polyparaphenylene terephthalamide, and polybenzazole are particularly suitable.
[0022]
<Measurement method of orientation parameters>
Hereinafter, the measurement method of electron beam diffraction and the evaluation method of the crystal orientation parameter <sin ² φ> will be described in detail. An ultrathin slice for electron microscope observation was prepared using a diamond knife (for example, Diatome) in which the core wire was embedded in an epoxy resin. The prepared sections were collected on a mesh, and an electron diffraction image was taken using an electron microscope. As an electron microscope to be used, for example, JEOL JEM-2010 may be operated at an acceleration voltage of 200 kV. The diffraction image was recorded using an imaging plate (FDL UR-V) manufactured by Fuji Photo Film Co., Ltd. Furthermore, the signal intensity was read with PIXsysTEM 20 manufactured by JEOL Ltd. using Fuji Photo Film Co., Ltd. digital micrography (FDL5000). The crystal orientation parameter was calculated according to the equation defined by Equation 1 after correcting background scattering from the azimuth diffraction intensity distribution along the Debye ring of the (002) diffraction plane.
[0023]
[Expression 1]

[0024]
Where I (φ) is the azimuth distribution of the diffraction intensity after background correction measured along the Debye ring of the (002) diffraction plane, and φ is the azimuth angle measured with the maximum point of the azimuthal diffraction intensity profile as the origin. It is.
[0025]
(Raman scattering measurement)
The Raman scattering spectrum was measured by the following method. The Raman measuring device (spectrometer) was measured using a Renishaw system 1000. The light source was a helium-neon laser (wavelength 633 nm), and the measurement was performed with the fibers placed so that the fiber axis was parallel to the polarization direction. Single fiber (monofilament) is split from yarn and pasted on the center line of a hole in a cardboard with a rectangular hole (50 mm in length and 10 mm in width) so that the long axis coincides with the fiber axis, and both ends are bonded with epoxy Stopped with an agent (Araldite) and left for more than 2 days. After that, the fiber is attached to a jig whose length can be adjusted with a micrometer, the cardboard holding the single fiber is carefully cut out, a predetermined strain is applied to the fiber, and it is placed on the microscope stage of the Raman scattering apparatus, and the Raman spectrum is obtained. It was measured. At this time, the stress acting on the fibers was simultaneously measured using a load cell.
[0026]
The present invention will be described below with reference to examples, but the present invention is of course not limited thereto. Each scale used for evaluation of this invention was calculated | required in the following procedure.
[0027]
<Fine fineness> The single yarn fineness was measured at a sample length of 50 mm and a number of 20 using a Denicon (manufactured by Search Co., Ltd.) for a sample adjusted for 24 hours in an atmosphere of a temperature of 20 ° C. and a humidity of 65 RH%. The average value was obtained. The total fineness was obtained by measuring the weight of a sample adjusted under the above conditions on a wrap reel by measuring 10 m and converting it to a weight of 9000 m.
[0028]
<Tensile properties of fiber bundles and cords> Using Tensilon manufactured by Orientec Co., Ltd. in accordance with JIS L-1013, the gripping interval was 20 cm, the tensile speed was 100% / min, and n = 10, and PC processing was performed. Tensile properties were determined.
[0029]
<Method of measuring knot strength> With one Z-strand main knot made at the center of the gripping interval of the sample, the knot strength was evaluated by measuring according to the tensile strength test method described above.
[0030]
<Method for measuring carbon content>
The carbon content was determined according to an organic elemental analysis method (for example, Yanaco MT-5 type CHN coder).
[0031]
The electrical conductivity may be measured using a general measuring device. For example, a HUSO ELECTRO CHEMICAL SYSTEM model 1116 may be used.
[0032]
【Example】
(Examples 1-4, Comparative Examples 1-2)
Polyparaphenylene benzobisoxazole having an intrinsic viscosity of 24.4 dL / g, measured with a methanesulfonic acid solution at 30 ° C., obtained by the method shown in US Pat. A spinning dope composed of polyphosphoric acid having 14.0% by weight and a phosphorus pentoxide content of 83.17% was used for spinning. The dope is passed through a metal mesh-like filter medium, then kneaded and defoamed with a biaxial kneading apparatus, and then the pressure is increased to maintain the polymer solution temperature at 170 ° C. and from a spinneret having a pore number of 33 After spinning at 170 ° C. and cooling the discharged yarn using cooling air at a temperature of 60 ° C., extraction is made of a 20% aqueous phosphoric acid solution at a temperature of 20 ± 2 ° C. Introduced into the coagulation bath. Subsequently, the yarn was washed with ion-exchanged water in the second extraction bath, and then immersed in 0.1N sodium hydroxide solution. Neutralization treatment was performed. Furthermore, after washing with water in a water bath, it was wound up and dried in a drying oven at 80 ° C. Furthermore, it was fired in a nitrogen atmosphere in an electric furnace heated to a predetermined firing temperature. After coating the polyimide stock solution on the core wire thus produced, coating was performed by allowing the polymerization reaction to proceed on the surface of the core wire at 250 ° C. Finally, a polyvinyl chloride resin (PVC) coating was applied to the composite conducting wire to prepare an earphone cord. The obtained earphone cord was evaluated for solderability, cord diameter and the like. The evaluation results are shown in Table 1.
[0033]
[Table 1]

[0034]
(Comparative Example 3)
Carbon nanotubes / polycarbonate / toluene (blending weight ratio = 10/40/50) were thoroughly stirred and extruded from the spinneret, and then the solvent was dried in an oven at 100 degrees to obtain fibers. Furthermore, it heated and baked at 1000 degreeC under nitrogen stream. The code was made in the same way as in Example 1. The results are shown in Table 1.
[0035]
【The invention's effect】
By using polybenzazole fiber as the tension member of the thin wire cord, a cord with excellent strength could be obtained. In particular, excellent flexibility (nodule strength) contributes to higher integration and complexity of circuits in the future. Furthermore, solderability can be improved by using fine and high-strength fibers. Since it has high strength, it can meet the demand for more advanced wire diameter reduction. As described above, an unprecedented small-diameter and high-strength electric wire cord can be manufactured industrially and efficiently, contributing to the industry.

Claims (4)

 A small-diameter electric wire cord characterized in that a core portion containing carbon nanotubes substantially made of carbon is used as a conductor, and the periphery of the conductor is covered with a thermoplastic resin. 2. The thin wire cord according to claim 1, wherein an orientation parameter of the carbon nanotube is 0.1 or less. The small-diameter electric wire cord according to claim 1, wherein the core portion has a Raman scattering peak appearing in a region of 1570-1610 cm- ¹ . Core portion, a small diameter according to claim 1, the half width of the minor peak the least line width of the Raman scattering peak is characterized in that it is of 60cm ^-1 or less present in the region of 1570-1610Cm ^-1 Electric wire cord.