JPH1112854A - Precursor fiber for acrylic carbon fiber and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a precursor fiber for an acrylic carbon fibers, slight in voids and difference in structure between internal and external structures of single fibers and excellent in tensile characteristics by adding water to a solution composed of a specific acrylic polymer and an organic solvent and producing the fiber under specific conditions. SOLUTION: Water is added to a solution composed of an acrylic polymer containing >=90 wt.% acrylonitrile and an organic solvent such as DMSO to provide a spinning solution containing 10-50 wt.% water based on the polymer. The resultant solution is once extruded from spinneret holes into a gas atmosphere and then led into a coagulation bath at <=10 deg.C to regulate the swelling degree of the undrawn yarn after washing with water to 150-250%. The swelling degree after the drawing in the bath is further regulated to <=150% to afford a precursor fiber for the acrylic carbon fibers having a substantially circular cross sectional shape of the single fiber, 70-95% orientation degree with wide angle X-rays, capable of proceeding the dissolution in the similar shape of the cross section of the single fiber and having a constant dissolution rate in the radial direction in tests for dissolving the fibers with a solvent.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、アクリル系炭素繊
維前駆体繊維、特に機械的特性に優れた炭素繊維を製造
するためのアクリル系炭素繊維前駆体繊維に関する。The present invention relates to an acrylic carbon fiber precursor fiber, and more particularly to an acrylic carbon fiber precursor fiber for producing a carbon fiber having excellent mechanical properties.

【０００２】[0002]

【従来の技術】炭素繊維は比強度、比弾性率に優れてい
るため、その特長を生かしてスポーツ用品、航空、宇宙
および一般産業用途に広く使われている。その用途開発
のためにはコスト低下とともに、依然高性能化が重要で
ある。2. Description of the Related Art Since carbon fibers have excellent specific strength and specific elastic modulus, carbon fibers are widely used in sports equipment, aviation, space and general industrial applications by utilizing their features. In order to develop its applications, it is still important to improve the performance as well as reduce the cost.

【０００３】従来、炭素繊維の高性能化およびそのため
の前駆体繊維の高性能化については多くの技術が提案さ
れている。Hitherto, many techniques have been proposed for improving the performance of carbon fibers and the performance of precursor fibers therefor.

【０００４】たとえば、繊維内部の異物やマクロボイド
を減少させるために、モノマーあるいはポリマー原液の
ろ過を強化する技術（たとえば、特開昭５９−８８９２
４号公報、特公平４−１２８８２号公報）が提案されて
いる。また表面欠陥の生成抑制について、製糸工程での
ガイドの形状およびガイドに接する糸の張力を規定する
ことにより表面欠陥生成を抑制する技術（たとえば、特
公平３−４１５６１号公報）などが提案されている。[0004] For example, in order to reduce foreign matter and macrovoids inside the fiber, a technique for enhancing the filtration of a monomer or polymer stock solution (for example, Japanese Patent Application Laid-Open No. 59-8892).
No. 4, Japanese Patent Publication No. 4-12882). Regarding the suppression of generation of surface defects, a technique (for example, Japanese Patent Publication No. 3-41561) for suppressing the generation of surface defects by defining the shape of the guide and the tension of the yarn in contact with the guide in the spinning process has been proposed. I have.

【０００５】前駆体繊維を製糸し、その後でさらに高温
下で耐炎化、炭化する炭素繊維の製造工程においては、
単繊維間の接着が発生しやすく、この単繊維間接着およ
びそれが剥がれた後が表面欠陥の原因となり、強度低下
要因となっている。[0005] In a process for producing a carbon fiber, which is used to produce a precursor fiber, and then to perform flame resistance and carbonization at a higher temperature,
Adhesion between the single fibers is liable to occur, and the adhesion between the single fibers and after it is peeled off causes surface defects, which is a factor of lowering the strength.

【０００６】このような単繊維間接着を抑制するため
に、製糸工程油剤を高性能化する技術も種々提案されて
いる。たとえば、従来の高級アルコールなどの非シリコ
ーン油剤に対して、耐熱性、離型性、平滑性に優れたシ
リコーン系油剤を適用する技術（たとえば、特公昭６０
−１８３３４号公報、特公平３−４０１５２号公報、特
公平４−３３８９２号公報、特公平５−８３６４２号公
報など）が提案されている。[0006] In order to suppress such adhesion between single fibers, various techniques have been proposed for improving the performance of an oil agent in a yarn-making process. For example, a technique of applying a silicone oil excellent in heat resistance, releasability, and smoothness to a conventional non-silicone oil such as a higher alcohol (for example, Japanese Patent Publication No.
-18334, JP-B-3-40152, JP-B4-33892, JP-B-5-83642, etc.).

【０００７】しかし、ろ過強化あるいは工程のガイドな
どによる表面欠陥生成抑制および高性能油剤による単繊
維間接着防止といった技術は、マクロ欠陥の生成抑制に
は効果があっても、繊維の基質、構造を変えることはで
きず、マクロ欠陥が減少した状態でのさらなる高性能化
の効果は不十分であった。[0007] However, techniques such as suppression of surface defect generation by filtration enhancement or process guide and prevention of adhesion between single fibers by a high performance oil are effective in suppressing the generation of macro defects, but the substrate and structure of the fiber are reduced. It could not be changed, and the effect of further improving the performance in a state where the macro defects were reduced was insufficient.

【０００８】一方、アクリル系ポリマーを湿式紡糸して
凝固繊維化する過程で生成する繊維内のボイドを減少し
て高強度化する技術として、特公平２−８０４９号公報
が提案されている。この技術はアクリロニトリル系重合
体を有機溶剤と水の混合物からなる溶剤に溶解し、該重
合体に対し５〜３０ｗｔ％の水を含む紡糸原液となし、
ついで該有機溶剤の水溶液からなる凝固浴に湿式紡糸し
て膨潤度が１３０％以下の未延伸糸を調整することから
なっている。しかしながら、水含有原液を湿式紡糸、乾
湿式紡糸して未延伸糸の膨潤度を１３０％以下に調整す
ることによって、未延伸糸のボイド量は減少するもの
の、単繊維の半径方向の構造差が拡大するため、十分な
強度向上効果が得られないという問題があった。On the other hand, Japanese Patent Publication No. 2-8049 has been proposed as a technique for increasing the strength by reducing the voids in the fibers formed in the process of coagulating fibers by wet spinning an acrylic polymer. In this technique, an acrylonitrile polymer is dissolved in a solvent comprising a mixture of an organic solvent and water, and a spinning solution containing 5 to 30% by weight of water with respect to the polymer is formed.
Next, the unstretched yarn having a degree of swelling of 130% or less is prepared by wet spinning in a coagulation bath comprising an aqueous solution of the organic solvent. However, by adjusting the swelling degree of the undrawn yarn to 130% or less by wet-spinning or dry-wet spinning the water-containing stock solution, the void amount of the undrawn yarn is reduced, but the structural difference in the radial direction of the single fiber is reduced. Because of the enlargement, there is a problem that a sufficient strength improving effect cannot be obtained.

【０００９】アクリル系前駆体繊維は、通常はポリマと
溶媒からなる均一な紡糸原液を口金孔から凝固剤（通常
は水）を含む凝固浴中に押し出す湿式紡糸、または、い
ったん空気中に押し出してから凝固浴中に導く乾湿式紡
糸によって凝固剤が均一な原液中に表面から浸入して、
溶媒の溶解力の低下とともにポリマが均一溶液から相分
離し繊維を形成する。この凝固過程で、紡糸引き取りに
よるドラフトがかかり、初期にポリマが相分離する表層
部ほど分子配向が高まり、緻密性も向上する。さらに、
温水浴中や加圧スチーム等で延伸されるため、その紡糸
および延伸工程において、内層と外層との構造差が大き
くなり、高緻密な表層部が耐炎化時の酸素透過を阻害し
て、耐炎化糸の単繊維において表層部と内層部で酸化の
程度に差ができ、それが焼成後の炭素繊維の機械的特性
にも影響を及ぼすという問題があった。[0009] The acrylic precursor fiber is usually a wet spinning method in which a uniform spinning solution composed of a polymer and a solvent is extruded from a spinneret into a coagulation bath containing a coagulant (usually water), or is once extruded into air. The coagulant penetrates into the uniform undiluted solution from the surface by dry-wet spinning that leads into the coagulation bath from
As the solvent dissolves, the polymer phase separates from the homogeneous solution to form fibers. In this coagulation process, draft is applied by spinning-off, and the molecular orientation increases and the denseness improves in the surface layer where the polymer is phase-separated in the initial stage. further,
Since the film is drawn in a hot water bath or under pressure steam, the structural difference between the inner layer and the outer layer increases in the spinning and drawing steps, and the high-density surface layer impedes oxygen permeation during flame resistance, resulting in flame resistance. There was a problem that the degree of oxidation was different between the surface layer portion and the inner layer portion of the single fiber of the knitted yarn, which also affected the mechanical properties of the fired carbon fiber.

【００１０】本発明者らは、この前駆体繊維の単繊維の
内外構造差に着目して鋭意検討した結果、水含有原液を
乾湿式紡糸するにあたり、低温度の凝固浴で急冷するこ
とにより、凝固剤の浸入速度を遅らせ、かつ原液中の水
によって、自ら内部からも凝固あるいはゲル化すること
によって内外層を均一に凝固させ、凝固時の繊維の体積
収縮を抑制し、未延伸糸の膨潤度を１５０％以上２５０
％以下に調整し、浴延伸後の膨潤度を１５０％以下に調
整することによって、前駆体繊維のボイド量の減少およ
び内外構造差の減少を同時に達成し、炭素繊維の強度を
飛躍的に向上できることを見いだし本発明に到達した。The present inventors have conducted intensive studies focusing on the difference in the inner and outer structures of the single fibers of the precursor fibers. As a result, when the water-containing stock solution was dry-wet spinning, it was rapidly cooled in a low-temperature coagulation bath. Slows the infiltration rate of the coagulant, and also solidifies or gels itself from the inside by the water in the stock solution, thereby uniformly coagulating the inner and outer layers, suppressing the volume shrinkage of the fiber during coagulation, and swelling the undrawn yarn. Degree is more than 150% 250
%, And the swelling degree after bath stretching is adjusted to 150% or less, thereby simultaneously reducing the amount of voids in the precursor fiber and reducing the difference in inner and outer structures, and dramatically improving the strength of the carbon fiber. They have found what they can do and arrived at the present invention.

【００１１】[0011]

【発明が解決しようとする課題】本発明の課題は、すな
わち、機械的特性、特に引張特性に優れた炭素繊維を製
造するための、ボイドが少なく、単繊維の内外構造差が
少ないアクリル系炭素繊維用前駆体繊維およびその製造
方法を提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide an acrylic carbon material having a small number of voids and a small difference between the inner and outer structures of a single fiber for producing a carbon fiber having excellent mechanical properties, especially tensile properties. An object of the present invention is to provide a precursor fiber for a fiber and a method for producing the same.

【００１２】[0012]

【課題を解決するための手段】上記した課題を解決する
ために、本発明の炭素繊維用前駆体繊維は以下の構成を
有する。すなわち、広角Ｘ線による配向度が７０％以
上、９５％以下であり、かつ繊維を溶剤で溶解する試験
において、単繊維の断面形状が実質的に相似形で溶解が
進行し、その溶解速度が半径方向に実質的に一定で内外
構造差の小さいアクリル系炭素繊維用前駆体繊維であ
る。In order to solve the above-mentioned problems, the precursor fiber for carbon fiber of the present invention has the following constitution. That is, in a test in which the degree of orientation by wide-angle X-rays is 70% or more and 95% or less, and in a test in which a fiber is dissolved with a solvent, the dissolution proceeds with a substantially similar cross-sectional shape of the single fiber, and the dissolution rate is increased. It is a precursor fiber for acrylic carbon fiber that is substantially constant in the radial direction and has a small difference in inner and outer structures.

【００１３】また、本発明の炭素繊維用前駆体繊維の製
造方法は以下の構成を有する。すなわち、アクリロニト
リルを９０ｗｔ％以上含有するアクリル系重合体と有機
溶剤とからなる溶液に水を添加し、該重合体に対して１
０〜５０ｗｔ％の水を含む均一な紡糸原液となし、口金
孔からいったん３０℃以下の気体雰囲気中に押し出した
後、１０℃以下の凝固浴中に導き、水洗後の未延伸糸の
膨潤度を１５０〜２５０％に調整し、さらに浴延伸後の
膨潤度を１５０％以下に調整することからなる。The method for producing a precursor fiber for carbon fiber of the present invention has the following constitution. That is, water is added to a solution comprising an acrylic polymer containing acrylonitrile at 90% by weight or more and an organic solvent, and 1% is added to the polymer.
A uniform spinning dope containing water of 0 to 50 wt%, and after being extruded from a die hole into a gas atmosphere of 30 ° C or less, guided into a coagulation bath at 10 ° C or less, and swelling degree of undrawn yarn after washing with water Is adjusted to 150 to 250%, and the degree of swelling after bath stretching is adjusted to 150% or less.

【００１４】[0014]

【発明の実施の形態】以下、本発明のアクリル系炭素繊
維用前駆体繊維について詳細に説明する。BEST MODE FOR CARRYING OUT THE INVENTION The precursor fiber for acrylic carbon fiber of the present invention will be described in detail below.

【００１５】すなわち、本発明のアクリル系炭素繊維用
前駆体繊維は、広角Ｘ線による配向度が７０％以上、９
５％以下であり、かつ繊維を溶剤で溶解する試験におい
て単繊維の断面形状が実質的に相似形で溶解が進行し、
その溶解速度が半径方向に実質的に一定で内外構造差の
小さいことを特徴とするアクリル系炭素繊維用前駆体繊
維である。That is, the precursor fiber for acrylic carbon fiber of the present invention has a degree of orientation by wide-angle X-ray of 70% or more and 9% or more.
5% or less, and in a test for dissolving the fiber with a solvent, the dissolution proceeds in a substantially similar cross-sectional shape of the single fiber,
A precursor fiber for an acrylic carbon fiber, characterized in that the dissolution rate is substantially constant in the radial direction and the difference between the inner and outer structures is small.

【００１６】広角Ｘ線による配向度が７０％以上、９５
％以下であることにより、焼成後の炭素繊維が機械的特
性に優れたものになる。広角Ｘ線による配向度が７０％
以下では配向が低く、耐熱性が低いために、焼成で単糸
間が融着しやすい構造となり、引張強度や弾性率の低い
炭素繊維しか得られない。また９５％を超えると、配向
は良いものの、焼成工程で単糸切れが起きやすくなり、
品位の良い炭素繊維を得ることが難しくなる。The degree of orientation by wide-angle X-rays is 70% or more and 95% or more.
% Or less, the fired carbon fiber has excellent mechanical properties. 70% orientation degree by wide-angle X-ray
In the following, since the orientation is low and the heat resistance is low, the structure becomes easy to fuse between the single yarns by firing, and only carbon fibers having low tensile strength and low elastic modulus can be obtained. If it exceeds 95%, although the orientation is good, single yarn breakage tends to occur in the firing step,
It becomes difficult to obtain high quality carbon fiber.

【００１７】また、本発明の前駆体繊維は、繊維を溶剤
で溶解する試験において、単繊維の断面形状が実質的に
相似形で溶解が進行するものである。溶解途中の繊維断
面を観察した時に、局部的な虫食い状で溶解が進行して
いるような前駆体繊維は、繊維断面の円周方向の均質性
が悪く、局部的にボイドなどの欠点が存在しているので
好ましくない。Further, in the test for dissolving the fiber with a solvent, the precursor fiber of the present invention is one in which the cross-sectional shape of the single fiber is substantially similar and the dissolution proceeds. Precursor fibers in which the dissolution is progressing in the form of local worms when the cross section of the fiber being melted is observed have poor uniformity in the circumferential direction of the fiber cross section, and local defects such as voids are present. Is not preferred.

【００１８】また、本発明の前駆体繊維は、単繊維の溶
解速度が半径方向に実質的に一定で、内外構造差が小さ
いものである。前駆体繊維の内外構造差を小さくするこ
とによって、焼成後の炭素繊維の内外構造差も小さくな
り、それによって引張特性に優れた炭素繊維が得られ
る。従来のアクリル系炭素繊維用前駆体繊維は表層部の
方が内層部に比べて配向が高く緻密であり、表層部の方
が有機溶剤に溶解しにくく、溶解速度で約３倍以上遅い
ために、本発明で規定する表層部／内層部の溶解速度比
が０．３以下と内外構造差が大きいものである。本発明
の前駆体繊維は溶解速度の比が０．５〜２．０倍の範囲
であることが好ましく、さらに好ましくは、０．５〜
１．５倍、より好ましくは０．８〜１．２倍の範囲であ
る。この比が０．５未満では、従来のプリカーサーと同
様に得られる炭素繊維の外層の配向度が内層に比べて高
くなり、その結果、表面に応力集中して引張強度が十分
に発現しにくくなる。またこの比が２．０倍を超える
と、逆の方向に内外構造差が大きくなり好ましくない。
ここで言う表層部とは、単繊維の表面から半径方向に半
径の２５％までの深さまでを言い、内層部とは表面から
半径の４０〜８０％の深さを言う。In the precursor fiber of the present invention, the dissolution rate of the single fiber is substantially constant in the radial direction, and the difference between the inner and outer structures is small. By reducing the difference between the inner and outer structures of the precursor fiber, the difference between the inner and outer structures of the fired carbon fiber is also reduced, thereby obtaining a carbon fiber having excellent tensile properties. Conventional acrylic carbon fiber precursor fibers have a higher orientation and a higher density in the surface layer than in the inner layer, and the surface layer is harder to dissolve in the organic solvent, and the dissolution rate is about three times slower or more. The dissolution rate ratio of the surface layer portion / inner layer portion defined in the present invention is 0.3 or less, and the difference between the inner and outer structures is large. The precursor fiber of the present invention preferably has a dissolution rate ratio of 0.5 to 2.0 times, more preferably 0.5 to 2.0 times.
The range is 1.5 times, and more preferably 0.8 to 1.2 times. When this ratio is less than 0.5, the degree of orientation of the outer layer of the carbon fiber obtained in the same manner as the conventional precursor becomes higher than that of the inner layer, and as a result, stress is concentrated on the surface and it is difficult to sufficiently develop tensile strength. . On the other hand, if this ratio exceeds 2.0 times, the difference between the inner and outer structures increases in the opposite direction, which is not preferable.
Here, the surface layer portion refers to a depth of up to 25% of the radius in the radial direction from the surface of the single fiber, and the inner layer portion refers to a depth of 40 to 80% of the radius from the surface.

【００１９】次に、本発明のアクリル系炭素繊維用前駆
体繊維の製造方法について説明する。Next, a method for producing the precursor fiber for acrylic carbon fiber of the present invention will be described.

【００２０】すなわち、本発明のアクリル系炭素繊維用
前駆体繊維の製造方法は、アクリロニトリルを９０ｗｔ
％以上含有するアクリル系重合体と有機溶剤とからなる
溶液に水を添加し、該重合体に対して１０〜５０ｗｔ％
の水を含む均一な紡糸原液となし、口金孔からいったん
４０℃以下の気体雰囲気中に押し出した後、１０℃以下
の凝固浴中に導き、水洗後の未延伸糸の膨潤度を１５０
〜２５０％に調整し、浴延伸後の膨潤度を１５０％以下
に調整することを特徴とするアクリル系炭素繊維用前駆
体繊維の製造方法である。That is, in the method for producing a precursor fiber for acrylic carbon fiber of the present invention, acrylonitrile is mixed with 90 wt.
% To a solution comprising an acrylic polymer and an organic solvent containing 10% to 50% by weight of the polymer.
Of a uniform spinning solution containing water, and once extruded through a die hole into a gas atmosphere at 40 ° C. or lower, guided into a coagulation bath at 10 ° C. or lower, and the swelling degree of the undrawn yarn after washing with water was 150.
A method for producing a precursor fiber for an acrylic carbon fiber, wherein the swelling degree after bath stretching is adjusted to 150% or less.

【００２１】本発明における共重合体は、アクリロニト
リル成分が９０ｗｔ％以上であることが好ましい。９０
ｗｔ％以下では焼成時のポリマの軟化が著しくなり、弾
性率の低下とともに強度が低下して好ましくない。該共
重合体に対する水の量は、紡糸原液を冷却した時に原液
自体が含有する凝固剤である水によって、凝固もしくは
ゲル化する量が好ましく、共重合体に対して１０〜５０
ｗｔ％、さらに好ましくは３０〜５０％の水を含有した
均一な紡糸原液にすることが好ましい。１０ｗｔ％未満
では冷却による原液のゲル化もしくは凝固が不十分とな
り、均一な凝固が達成しにくくなる。一方、５０ｗｔ％
を越えると、水の溶解が困難となり、均一な紡糸原液を
作製するのがむつかしくなってくる。The acrylonitrile component in the copolymer of the present invention is preferably 90% by weight or more. 90
If it is less than wt%, the softening of the polymer at the time of firing becomes remarkable, and the strength decreases with the decrease in the elastic modulus, which is not preferable. The amount of water with respect to the copolymer is preferably an amount which coagulates or gels with water which is a coagulant contained in the stock solution itself when the stock solution is cooled.
It is preferable to prepare a uniform spinning dope containing water by weight, more preferably 30 to 50%. If the content is less than 10 wt%, gelation or coagulation of the stock solution by cooling becomes insufficient, and uniform coagulation becomes difficult to achieve. On the other hand, 50 wt%
When the temperature exceeds the above range, it becomes difficult to dissolve water, and it becomes difficult to prepare a uniform spinning solution.

【００２２】水含有原液は口金孔からいったん４０℃以
下、好ましくは１０〜３０℃、さらに好ましくは１０〜
２０℃の気体雰囲気中に押し出した後、１０℃以下、好
ましくは５〜−１５℃、さらに好ましくは０〜−１５℃
の凝固浴中に導入し、繊維化することが重要である。１
０℃以下の凝固浴で急冷することによって、原液中に含
まれる水の作用により、凝固浴中の水が浸入しなくとも
原液自体が凝固もしくはゲル化すると同時に、凝固浴の
水の浸入が抑制されるため、断面方向の凝固が均一に進
行するので好ましい。凝固浴の温度は低いほど好まし
く、有機溶剤の種類や水溶液の濃度による氷点引で限定
されるが、−１５℃以上が経済的に好ましい。低温凝固
浴で急冷することによって、断面方向の凝固が均一に進
行すると同時に、凝固時の体積収縮が抑制されるため、
全体としては極めて微細な多数のボイドが生成し、凝
固、水洗した未延伸糸の膨潤度は通常よりは大きくな
る。The stock solution containing water is once at 40 ° C. or lower, preferably 10 to 30 ° C., and more preferably 10 to 30 ° C.
After being extruded into a gas atmosphere of 20 ° C, it is 10 ° C or less, preferably 5 to -15 ° C, more preferably 0 to -15 ° C.
It is important that it is introduced into a coagulation bath and fiberized. 1
By quenching in a coagulation bath at 0 ° C or lower, the water contained in the undiluted solution acts to coagulate or gel the undiluted solution itself without the infiltration of water in the coagulation bath, and at the same time suppresses the infiltration of water in the coagulation bath. Therefore, solidification in the cross-sectional direction proceeds uniformly, which is preferable. The temperature of the coagulation bath is preferably as low as possible, and is limited by the freezing point depending on the type of the organic solvent and the concentration of the aqueous solution, but -15 ° C or more is economically preferable. By rapid cooling in a low-temperature coagulation bath, solidification in the cross-sectional direction progresses uniformly and at the same time, volume shrinkage during solidification is suppressed,
As a whole, a large number of extremely fine voids are formed, and the degree of swelling of the undrawn yarn solidified and washed with water is larger than usual.

【００２３】この未延伸糸の膨潤度は、共重合体組成、
紡糸原液中の共重合体濃度や水の含有量、溶剤種類、凝
固浴中の溶剤の種類や濃度および温度などによって影響
されるが、これらの条件を組み合わせて未延伸糸の膨潤
度を１５０％〜２５０％、好ましくは１８０〜２５０
％、さらに好ましくは２００〜２５０％に調整する。The degree of swelling of the undrawn yarn is determined by the copolymer composition,
It is affected by the copolymer concentration in the spinning solution, the water content, the type of solvent, the type and concentration of the solvent in the coagulation bath, the temperature, and the like. These conditions are combined to reduce the degree of swelling of the undrawn yarn by 150%. ~ 250%, preferably 180 ~ 250
%, More preferably 200 to 250%.

【００２４】膨潤度が１５０％未満では凝固時の体積収
縮の抑制が不十分で、断面方向の凝固が不均一となり好
ましくない。一方、２５０％を越えると浴延伸によって
ボイドが潰れにくくなり、浴延伸糸の膨潤度が高くなっ
て、油剤を付与した時に油剤が繊維内部に浸入すること
によって緻密化を阻害し、局部的にボイドが偏在するな
どして、繊維の溶解試験で断面が相似形ではなく、虫食
い状に溶解が進行することが多い。このような前駆体繊
維は炭素繊維の欠陥になり好ましくない。従って油剤を
付与する前の浴延伸糸にボイドが少ないことが重要であ
り、浴延伸糸の膨潤度を１５０％以下に調整することが
好ましい。If the degree of swelling is less than 150%, the suppression of volume shrinkage during solidification is insufficient, and the solidification in the cross-sectional direction is not uniform, which is not preferable. On the other hand, if it exceeds 250%, the voids are unlikely to be crushed by bath stretching, the degree of swelling of the bath drawn yarn increases, and when the oil agent is applied, the oil agent penetrates into the interior of the fiber, thereby hindering densification. Due to uneven distribution of voids and the like, dissolution often progresses in a bug-like manner in cross section in a fiber dissolution test, which is not similar. Such precursor fibers are undesirable because they cause defects of carbon fibers. Therefore, it is important that the bath-drawn yarn before applying the oil agent has few voids, and the swelling degree of the bath-drawn yarn is preferably adjusted to 150% or less.

【００２５】浴延伸糸の膨潤度を１５０％以下にするた
めには、共重合体の親水性を向上させ、凝固浴を低温に
するなどして未延伸糸のボイド構造を微細にしておき、
さらに浴延伸の最高温度を６０℃以上として延伸するこ
とが好ましい。In order to reduce the degree of swelling of the bath-drawn yarn to 150% or less, the void structure of the undrawn yarn is reduced by improving the hydrophilicity of the copolymer and lowering the temperature of the coagulation bath.
Further, it is preferable that the maximum temperature of the bath stretching is 60 ° C. or more, and the stretching is performed.

【００２６】膨潤度を１５０％以下に調整された浴延伸
糸は、引き続き常法に従って油剤の付与、乾燥緻密化、
必要に応じてスチーム延伸などを施して、広角Ｘ線の結
晶配向度が７０％以上、９５％以下の前駆体繊維とする
ものである。以下詳細に説明する。The stretched bath yarn whose swelling degree has been adjusted to 150% or less is continuously applied with an oil agent, dried and densified according to a conventional method.
If necessary, the fiber is stretched by steam or the like to obtain a precursor fiber having a degree of crystal orientation of wide-angle X-rays of 70% or more and 95% or less. This will be described in detail below.

【００２７】共重合体の組成としては、カルボキシル
基、スルホ基、アミノ基、アミド基等の親水性の官能基
を有するビニル化合物が好ましい。具体例としては、ア
クリル酸、メタクリル酸、イタコン酸、クロトン酸、シ
トラコン酸、エタクリル酸、マレイン酸、メサコン酸な
どが挙げられるが、特にアクリル酸、メタクリル酸、イ
タコン酸およびそれらのエステルが耐炎化促進効果の面
で好ましいが、酸をアンモニウム塩にして親水性を付与
することがより好ましい。As the composition of the copolymer, a vinyl compound having a hydrophilic functional group such as a carboxyl group, a sulfo group, an amino group and an amide group is preferable. Specific examples include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, citraconic acid, ethacrylic acid, maleic acid, mesaconic acid, and the like.In particular, acrylic acid, methacrylic acid, itaconic acid and esters thereof are flame-resistant. Although it is preferable in terms of the promoting effect, it is more preferable to convert the acid to an ammonium salt to impart hydrophilicity.

【００２８】共重合量としては、少なすぎると耐炎化促
進および親水性の付与がむつかしくなり、また多すぎる
とアクリロニトリル本来の特性が減少してしまうので好
ましくなく、アクリロニトリル以外の共重合組成の合計
は０．１〜１０ｗｔ％の範囲にすることが好ましく、
０．５〜４ｗｔ％がより好ましい。If the copolymerization amount is too small, it is difficult to promote flame resistance and impart hydrophilicity. If the copolymerization amount is too large, the intrinsic properties of acrylonitrile decrease, which is not preferable. The total of the copolymer composition other than acrylonitrile is Preferably, it is in the range of 0.1 to 10 wt%,
0.5-4 wt% is more preferable.

【００２９】重合度については、特に限定されないが、
製糸性、炭素繊維品質等の面からポリマの極限粘度
［η］が０．８〜３．５の範囲のものが好ましく、１．
１〜２．５がより好ましい。Although the degree of polymerization is not particularly limited,
It is preferable that the intrinsic viscosity [η] of the polymer is in the range of 0.8 to 3.5 from the viewpoints of the spinning property and the quality of carbon fiber.
1 to 2.5 is more preferable.

【００３０】なお、重合法については、溶液重合、懸濁
重合、乳化重合等の公知の重合法を適用することができ
るが、有機溶剤中での溶液重合が好ましい。As the polymerization method, known polymerization methods such as solution polymerization, suspension polymerization and emulsion polymerization can be applied, but solution polymerization in an organic solvent is preferred.

【００３１】紡糸に供する共重合体の濃度については、
高いほど凝固での沈殿剤との置換量が少ないため緻密に
なり、炭素繊維の強度向上にとって有効であるが、一方
共重合体原液の粘度が高くなる、ゲル化しやすい、製糸
延伸性が低下するといった製糸プロセス性が低下するた
め、そのバランスから決めることが好ましい。具体的に
は共重合体濃度で１０〜３０重量％が好ましく、１５〜
２５重量％がより好ましい。Regarding the concentration of the copolymer to be spun,
The higher the value, the smaller the amount of substitution with the precipitant in the coagulation, so that the carbon fiber becomes denser, which is effective for improving the strength of the carbon fiber. Therefore, it is preferable to determine from the balance. Specifically, the copolymer concentration is preferably 10 to 30% by weight, and
25% by weight is more preferred.

【００３２】水含有原液の作製法としては、有機溶剤と
水の混合液に共重合体を溶解して均一な紡糸原液を作製
すると、貯蔵中にゲル化が進行し、紡糸性が悪化もしく
は紡糸不可能となるので好ましくない。本発明の製造法
としては、先ずポリマとポリマに対する割合が２．５重
量％以下の水と有機溶剤からなる均一溶媒を作製し、紡
糸する段階で吐出計量ギヤポンプの前の送液ラインに設
置した混練機に必要量の水を連続的に注入し、加圧下で
連続混練・溶解しながら送液し紡糸する。この方法では
水含有原液の滞留時間が極めて短縮できるため、原液の
ゲル化が防止でき、紡糸安定性および品質の面から好ま
しい。水添加量が多い場合は混練機の温度をある程度高
く設定することが好ましい。As a method for preparing a water-containing stock solution, if a uniform spinning solution is prepared by dissolving a copolymer in a mixed solution of an organic solvent and water, gelation proceeds during storage and spinnability deteriorates or spinning becomes worse. It is not preferable because it becomes impossible. In the production method of the present invention, first, a homogeneous solvent composed of water and an organic solvent having a ratio of polymer to polymer of 2.5% by weight or less is prepared, and is installed in a liquid sending line in front of a discharge metering gear pump in a spinning stage. A required amount of water is continuously poured into a kneader, and the mixture is fed while continuously kneading and dissolving under pressure to spin. In this method, the residence time of the water-containing stock solution can be extremely shortened, so that gelation of the stock solution can be prevented, which is preferable in terms of spinning stability and quality. When the amount of water added is large, it is preferable to set the temperature of the kneader to a somewhat high level.

【００３３】紡糸方法としては、低温凝固浴で生産性を
低下させることなく製糸できる乾湿式紡糸法が好ましく
採用される。As a spinning method, a dry-wet spinning method capable of spinning in a low-temperature coagulation bath without lowering productivity is preferably employed.

【００３４】溶剤としては、ＤＭＳＯ、ＤＭＦ、ＤＭＡ
ｃ等の従来公知の有機溶剤を使うことができるが、生産
性の面から凝固速度が早いＤＭＳＯが特に好ましい。As the solvent, DMSO, DMF, DMA
Although a conventionally known organic solvent such as c can be used, DMSO having a high solidification rate is particularly preferable from the viewpoint of productivity.

【００３５】水を所定量含有した紡糸原液は計量ギヤポ
ンプで口金孔から空気中に押し出される。吐出される原
液温度は８０℃以下、好ましくは５５℃以下まで冷却
し、数ｍｍのエアーギャップの後、凝固浴に導入するこ
とが好ましいが、８０℃以下では自己凝固してしまう水
含有量の場合はエアーギャップを数十〜数百ｃｍとって
冷風等によって冷却してから凝固浴に導入することが好
ましい。The spinning solution containing a predetermined amount of water is extruded into the air from a die hole by a metering gear pump. The temperature of the undiluted solution to be discharged is cooled to 80 ° C. or less, preferably to 55 ° C. or less, and is preferably introduced into a coagulation bath after an air gap of several mm. In this case, it is preferable to introduce an air gap of several tens to several hundreds cm and cool it with cold air or the like before introducing it into the coagulation bath.

【００３６】凝固浴中の有機溶剤の濃度は円形孔の口金
を使用した場合、凝固糸の断面形状が実質的に円形にな
る条件に設定することが好ましい。断面が非円形になる
と繊維半径方向の構造の均一性が低下するので好ましく
ない。The concentration of the organic solvent in the coagulation bath is preferably set to a condition that the cross-sectional shape of the coagulated yarn becomes substantially circular when a die having a circular hole is used. A non-circular cross section is not preferable because the uniformity of the structure in the fiber radial direction decreases.

【００３７】凝固引き取り、水洗、温水〜熱水浴延伸し
た膨潤糸に油剤の付与を付与する。油剤としてはアミノ
変性および／またはエポキシ変性シリコーンを主体とす
るシリコーン系油剤を繊維重量に対し０．１〜５ｗｔ％
付与するのが好ましいが、単繊維間の接着を防止するこ
とが重要であり、限定されるものではない。The oily agent is imparted to the swollen yarn which has been coagulated, washed, washed, and stretched from warm water to a hot water bath. As the oil, a silicone oil mainly composed of amino-modified and / or epoxy-modified silicone is used in an amount of 0.1 to 5% by weight based on the fiber weight.
Although it is preferable to provide, it is important to prevent adhesion between single fibers, and there is no limitation.

【００３８】油剤付与後、乾燥緻密化、必要に応じて常
圧あるいは加圧スチーム延伸等を行うが、製糸全延伸倍
率は得られる前駆体繊維の広角Ｘ線による繊維軸方向の
結晶配向度π400 が７０％以上、９５％以下になるよう
に設定される。After the application of the oil agent, drying and densification and, if necessary, normal pressure or pressure steam drawing are performed. The total draw ratio of the obtained fiber is determined by the degree of crystal orientation π400 in the fiber axis direction of the obtained precursor fiber by wide-angle X-rays. Is set to be 70% or more and 95% or less.

【００３９】得られた均質な構造を有するプリカーサー
を常法に従って耐炎化、炭化することによって、引張強
度が６ＧＰａ以上の高強度・高伸度の炭素繊維を得るこ
とができる。By subjecting the obtained precursor having a homogeneous structure to flame resistance and carbonization according to a conventional method, a high-strength and high-elongation carbon fiber having a tensile strength of 6 GPa or more can be obtained.

【００４０】[0040]

【実施例】以下、実施例により本発明をさらに具体的に
説明する。The present invention will be described more specifically with reference to the following examples.

【００４１】なお本発明において広角Ｘ線によるプリカ
ーサーの繊維軸方向の結晶配向度π400 は次の方法によ
り求めた。試料約２０ｍｇ／４ｃｍを１ｍｍ幅の金型に
コロジオンで固めて測定に供する。Ｘ線源としてＮｉフ
ィルターで単色化したＣｕのＫα線（波長：１．５４１
８Ａ）を使用し、出力３５ｋＶ、１５ｍＡで測定し、２
θ＝１７゜付近に観察された面指数（４００）のピーク
を円周方向にスキャンして得られたピークの半値幅Ｈ
（゜）より、 π400 （％）＝（１８０−Ｈ）×１００／１８０ の式から求めた。なお、ゴニオメーターのスリット直径
としては２ｍｍ、計数管としてはシンチレーションカウ
ンターを用いた。スキャン速度は４゜／分、タイムコン
スタント１秒、チャートスピードは１ｃｍ／分である。In the present invention, the degree of crystal orientation π400 in the fiber axis direction of the precursor by wide-angle X-ray was determined by the following method. Approximately 20 mg / 4 cm of a sample is solidified in a mold having a width of 1 mm with a collodion and used for measurement. Cu Kα radiation monochromatic with a Ni filter as an X-ray source (wavelength: 1.541
8A), and measured at an output of 35 kV and 15 mA.
The half value width H of the peak obtained by scanning the peak of the plane index (400) observed around θ = 17 ° in the circumferential direction.
From (゜), it was determined from the equation: π400 (%) = (180−H) × 100/180. The goniometer had a slit diameter of 2 mm and a counter tube was a scintillation counter. The scanning speed is 4 ° / min, the time constant is 1 second, and the chart speed is 1 cm / min.

【００４２】繊維の溶剤による溶解試験は次の方法で実
施する。溶剤としてはＤＭＳＯを用いた。The dissolution test of the fiber with a solvent is carried out by the following method. DMSO was used as a solvent.

【００４３】先ず繊維束を約１０ｃｍの長さにカット
し、ハンドカードで開繊する。開繊後の繊維約１ｇを精
評しＷ0 とする。５００ｃｃの共栓付き三角フラスコに
２００ｃｃのＤＭＳＯを入れ、振蕩式恒温槽にセットす
る。ＤＭＳＯの温度は予備試験によってその繊維の重量
の５０％を溶解するに要する時間が１５〜３０分になる
温度を決定し、±０．２℃以内の範囲で制御する。精評
済みの繊維を素早く恒温のＤＭＳＯに浸し所定時間溶解
処理した後素早く取り出し、室温の８６％、５５％、３
０％のＤＭＳＯ水溶液で順次それぞれ１分程度洗浄し、
最後に室温の流水で１０分以上かけて十分に洗浄する。
洗浄後、１００℃のオーブン中で絶乾し、冷却後、残存
繊維重量を精評しＷ1 とする。溶解処理時間を変えて順
次処理し、それぞれの残存率Ｗを次式１により求める。
残存率が２０％程度まで試験する。 残存率Ｗ＝（Ｗn ／Ｗ0 ）×１００（％） …（１） 次に溶解処理前の繊維密度（ρ）および単繊維繊度（デ
ニール：ｄ）から繊維断面を円形と仮定して溶解処理前
の単繊維半径ｒ0 （μｍ）および溶解残存繊維の半径ｒ
n （μｍ）をそれぞれ次式２および次式３より求める。
この時溶解処理後の繊維密度は溶解処理前と同じとす
る。π：円周率 ｒ0 ＝｛ｄ／（９０００・ρ・π）｝^1/2 ×１０００（μｍ） …（２） ｒn ＝｛（ｄ・Ｗ）／（９０００００・ρ・π）｝^1/2 ×１０００（μｍ） …（３） 次式４により、それぞれの溶解処理時間による繊維表面
から半径方向の溶解深さ（μｍ）を求める。First, the fiber bundle is cut into a length of about 10 cm and opened with a hand card. Approximately 1 g of the fiber after opening is carefully evaluated and designated as W0. 200 cc of DMSO is placed in a 500 cc stoppered Erlenmeyer flask and set in a shaking thermostat. The temperature of DMSO is determined by a preliminary test to determine the temperature at which the time required to dissolve 50% of the weight of the fiber becomes 15 to 30 minutes, and is controlled within a range of ± 0.2 ° C. The evaluated fiber is quickly immersed in a constant temperature DMSO and dissolved for a predetermined time, then quickly taken out, and 86%, 55%, 3% of room temperature.
Wash sequentially with 0% DMSO aqueous solution for about 1 minute each,
Finally, it is sufficiently washed with running water at room temperature for 10 minutes or more.
After washing, the sample is dried in an oven at 100 ° C., and after cooling, the weight of the remaining fiber is evaluated to be W1. The dissolution treatment time is changed and the treatment is performed successively, and the residual ratio W of each is determined by the following equation 1.
Test until the residual rate is about 20%. Residual rate W = (Wn / W0) × 100 (%) (1) Next, from the fiber density (ρ) and the single fiber fineness (denier: d) before the dissolution treatment, the fiber cross section is assumed to be circular before the dissolution treatment. Radius r0 (μm) of single fiber and radius r of dissolved residual fiber
n (μm) is obtained from the following equations 2 and 3, respectively.
At this time, the fiber density after the dissolution treatment is the same as that before the dissolution treatment. π: Pi r 0 = {d / (9000 · ρ · π)} ^1/2 × 1000 (μm) (2) rn = {(d · W) / (900000 · ρ · π)} ^1/2 × 1000 (μm) (3) The dissolution depth (μm) in the radial direction from the fiber surface at each dissolution treatment time is determined by the following equation 4.

【００４４】 半径方向の溶解深さ＝ｒ0 −ｒn …（４） 溶解時間を横軸にして半径方向の溶解深さを縦軸にグラ
フにプロットする。表層部（ｒ0 とｒn の差がｒ0 の０
〜２５％までの間）で４点以上、内層部（ｒ0とｒn の
差がｒ0 の４０〜８０％までの間）で４点以上プロット
されるように溶解時間を調整する。Dissolution depth in radial direction = r0−rn (4) Dissolution time in the radial direction is plotted on the vertical axis and dissolution time in the radial direction is plotted on the vertical axis. Surface layer (the difference between r0 and rn is 0
The dissolution time is adjusted so that four points or more are plotted in the inner layer (where the difference between r0 and rn is 40 to 80% of r0).

【００４５】表層部と内層部のプロットを最少二乗法で
直線近似してそれぞれの勾配を求め、溶解速度（μｍ／
分）とする。溶解速度比（表層部／内層部）が１に近い
ほど半径方向に均一な構造の前駆体繊維といえる。The plots of the surface layer portion and the inner layer portion were linearly approximated by the least-squares method to determine the respective gradients, and the dissolution rate (μm /
Minutes). As the dissolution rate ratio (surface layer / inner layer) approaches 1, it can be said that the precursor fiber has a more uniform structure in the radial direction.

【００４６】残存繊維の単繊維断面の切片を光学顕微鏡
などで観察して、溶解処理前の断面形状と相似形であれ
ば円周方向でも構造が均一といえる。A section of a single fiber cross section of the remaining fiber is observed with an optical microscope or the like. If the cross section is similar to the cross section before the dissolution treatment, the structure can be said to be uniform even in the circumferential direction.

【００４７】未延伸糸および浴延伸糸の膨潤度は回転数
３０００ｒｐｍの遠心脱水機で５分間脱水したあとの重
量Ｗ１、絶乾後の重量Ｗ０から次式５によって求めた。The degree of swelling of the undrawn yarn and the bath drawn yarn was determined by the following equation 5 from the weight W1 after dehydration for 5 minutes with a centrifugal dehydrator at a rotation speed of 3000 rpm and the weight W0 after absolute drying.

【００４８】 膨潤度＝｛（Ｗ１−Ｗ０）／Ｗ０｝×１００（％） …（５） （実施例１）アクリロニトリル９８．８モル％とアクリ
ル酸１．２モル％からなる共重合体を溶剤として、ＤＭ
ＳＯを用い溶液重合法により重合し、ポリマ濃度２２％
の紡糸原液を得た。重合後アンモニアガスをｐＨが８．
５になるまで吹き込みすることによりアクリル酸を中和
して、アンモニウム基をポリマーに導入することによ
り、紡糸原液の親水性を向上させた。得られた原液を２
軸混練機に導入し、混練機の中間からポリマに対して３
５ｗｔ％になるように水を定量ポンプで連続的に注入し
ながら混練機の先端側に設けられた吐出ギヤポンプによ
り紡糸原液の量を計量し、紡糸原液の温度を４５℃に制
御後、孔径０．１５ｍｍ、孔数６０００の口金から３０
℃空気中に押し出し、４ｍｍのエアーギャップを経て、
３℃にコントロールした３５％ＤＭＳＯの水溶液からな
る凝固浴に導き繊維化し、引き取った凝固糸を水洗した
後、５０〜９０℃の温水中で４段階に分けてトータル３
倍延伸した。未延伸糸および浴延伸糸の膨潤度はそれぞ
れ１８０％、８０％であった。Swelling degree = {(W1−W0) / W0} × 100 (%) (5) (Example 1) A copolymer comprising 98.8 mol% of acrylonitrile and 1.2 mol% of acrylic acid was dissolved in a solvent. As DM
Polymerized by solution polymerization method using SO, polymer concentration 22%
Was obtained. After polymerization, the ammonia gas is adjusted to pH 8.
Acrylic acid was neutralized by blowing to 5 to introduce ammonium groups into the polymer, thereby improving the hydrophilicity of the spinning stock solution. The obtained undiluted solution is 2
Introduced to the shaft kneader, 3
While continuously injecting water with a metering pump so as to be 5 wt%, the amount of the spinning dope was measured by a discharge gear pump provided at the tip side of the kneader, and after controlling the temperature of the spinning dope to 45 ° C., the pore diameter was reduced to 0%. .15mm, 30 from the base with 6000 holes
Extruded into the air through a 4mm air gap,
The fiber is guided into a coagulation bath consisting of an aqueous solution of 35% DMSO controlled at 3 ° C., fiberized, and the collected coagulated yarn is washed with water and then divided into 4 stages in warm water at 50 to 90 ° C. for a total of 3 steps.
It was stretched twice. The swelling degrees of the undrawn yarn and the bath drawn yarn were 180% and 80%, respectively.

【００４９】得られた水膨潤状態にある延伸糸にアミノ
変性シリコーンを主体とした油剤を付与し、表面温度１
５０℃の加熱ローラーを用いて定長で乾燥緻密化処理を
行った。An oil agent mainly composed of amino-modified silicone was applied to the obtained water-swollen drawn yarn, and the surface temperature was adjusted to 1
Dry densification treatment was performed at a fixed length using a heating roller at 50 ° C.

【００５０】得られた乾燥緻密化処理糸をさらに４ｋｇ
／ｃｍ² −Ｇの加圧スチーム中で延伸することにより、
製糸全延伸倍率を１３倍とし、単繊維繊度１ｄのアクリ
ル系前駆体繊維を得た。繊維の断面形状は円形であっ
た。4 kg of the obtained dried and densified yarn was further added.
/ Cm ² -G by stretching in pressurized steam,
The total draw ratio of the spinning was 13 times, and an acrylic precursor fiber having a single fiber fineness of 1d was obtained. The cross-sectional shape of the fiber was circular.

【００５１】得られた前駆体繊維を６０℃のＤＭＳＯ中
で溶解試験を行った結果、断面形状は円形の状態で溶解
が進行しており、半径方向の表層部／内層部の溶解速度
比は０．８であった。また、前駆体繊維の広角Ｘ線回折
による繊維軸方向の結晶配向度は９２．５％であった。The obtained precursor fiber was subjected to a dissolution test in DMSO at 60 ° C. As a result, the dissolution progressed in a circular cross section, and the dissolution rate ratio of the surface layer / inner layer in the radial direction was: 0.8. The degree of crystal orientation of the precursor fiber in the fiber axis direction by wide-angle X-ray diffraction was 92.5%.

【００５２】１２０００フィラメントの前駆体繊維を常
圧の加熱空気を循環する２４５℃と２６５℃の酸化処理
炉で延伸比を１．０として連続的に処理し、繊維比重が
１．３４の耐炎化繊維を得た。Precursor fibers of 12,000 filaments are continuously treated in an oxidation furnace at 245 ° C. and 265 ° C. circulating heated air at normal pressure with a draw ratio of 1.0, and are made flame-resistant to a specific gravity of 1.34. Fiber was obtained.

【００５３】得られた耐炎化繊維を窒素雰囲気で最高温
度８００℃のの前炭化炉で延伸比１．０２、次いで最高
温度１４５０℃の炭化炉で延伸比０．９８として焼成
し、炭素繊維を得た。次いで炭酸アンモニウムの水溶液
中で１０クーロン／ｇ−ＣＦの陽極酸化処理を行った。The obtained oxidized fiber was fired in a pre-carbonizing furnace at a maximum temperature of 800 ° C. in a nitrogen atmosphere at a draw ratio of 1.02, and then in a carbonization furnace at a maximum temperature of 1450 ° C. at a draw ratio of 0.98, and the carbon fibers were baked. Obtained. Next, an anodic oxidation treatment of 10 coulomb / g-CF was performed in an aqueous solution of ammonium carbonate.

【００５４】このようにして得られた炭素繊維の樹脂含
浸、硬化処理したストランドの強度および弾性率はそれ
ぞれ６．５ＧＰａ、２７５ＧＰａと極めて高品質の炭素
繊維であった。The strands obtained by impregnating and curing the carbon fibers obtained in this way with resin were extremely high quality carbon fibers of 6.5 GPa and 275 GPa, respectively.

【００５５】（実施例２）アクリロニトリル９９．６モ
ル％とイタコン酸０．４モル％からなる共重合体を溶剤
としてＤＭＳＯを用い溶液重合法により重合し、ポリマ
濃度２１％の紡糸原液を得た。重合後アンモニアガスを
ｐＨが８．５になるまで吹き込みすることによりイタコ
ン酸を中和して、アンモニウム基をポリマーに導入する
ことにより、紡糸原液の親水性を向上させた。得られた
原液を２軸混練機に導入し、混練機の中間からポリマに
対して２０ｗｔ％になるように水を定量ポンプで連続的
に注入しながら混練機の先端側に設けられた吐出ギヤポ
ンプにより紡糸原液の量を計量し、紡糸原液の温度を５
５℃に制御後、孔径０．１０ｍｍ、孔数６０００の口金
から２０℃の空気中に押し出し、４ｍｍのエアーギャッ
プを経て、０℃にコントロールした３５％ＤＭＳＯの水
溶液からなる凝固浴に導き繊維化し、引き取った凝固糸
を水洗した後、５０〜９０℃の温水中で４段階に分けて
トータル２．５倍延伸した。未延伸糸および浴延伸糸の
膨潤度はそれぞれ２１０％、９０％であった。Example 2 A solution consisting of 99.6 mol% of acrylonitrile and 0.4 mol% of itaconic acid was polymerized by a solution polymerization method using DMSO as a solvent to obtain a spinning solution having a polymer concentration of 21%. . After the polymerization, itaconic acid was neutralized by blowing ammonia gas until the pH reached 8.5, and an ammonium group was introduced into the polymer to improve the hydrophilicity of the spinning solution. The obtained undiluted solution is introduced into a twin-screw kneader, and water is continuously injected from a middle of the kneader by a constant-rate pump so as to be 20 wt% with respect to the polymer. The amount of the spinning solution is measured by using
After controlling to 5 ° C., it was extruded from a die having a hole diameter of 0.10 mm and a number of holes of 6000 into air at 20 ° C., and passed through a 4 mm air gap to a coagulation bath consisting of an aqueous solution of 35% DMSO controlled at 0 ° C. to form a fiber. After the washed coagulated yarn was washed with water, it was stretched in warm water at 50 to 90 ° C. in four stages, for a total of 2.5 times. The swelling degrees of the undrawn yarn and the bath drawn yarn were 210% and 90%, respectively.

【００５６】得られた水膨潤状態にある延伸糸にアミノ
変性シリコーンを主体とした油剤を付与し、表面温度１
５０℃の加熱ローラーを用いて定長で乾燥緻密化処理を
行い、製糸全延伸倍率２．５倍で単繊維繊度が１．５デ
ニールの前駆体繊維を得た。繊維の断面形状は円形であ
った。また、広角Ｘ線による結晶配向度は７２．０％で
あった。An oil agent mainly composed of amino-modified silicone was applied to the obtained water-swollen drawn yarn, and a surface temperature of 1% was applied.
Dry densification treatment was performed at a fixed length using a heating roller at 50 ° C. to obtain a precursor fiber having a total drawing ratio of 2.5 times and a single fiber fineness of 1.5 denier. The cross-sectional shape of the fiber was circular. The degree of crystal orientation by wide-angle X-ray was 72.0%.

【００５７】得られた前駆体繊維を２０℃のＤＭＳＯ中
で溶解試験を行った結果、断面形状は円形の状態で溶解
が進行しており、半径方向の表層部／内層部の溶解速度
比１．２であった。The obtained precursor fiber was subjected to a dissolution test in DMSO at 20 ° C. As a result, the dissolution progressed in a circular cross section, and the dissolution rate ratio of the surface layer / inner layer in the radial direction was 1: 1. .2.

【００５８】１２０００フィラメントの前駆体繊維を常
圧の加熱空気を循環する２３５℃と２５５℃の酸化処理
炉で延伸比を２．０として連続的に処理し、繊維比重が
１．３３の耐炎化繊維を得た。The precursor fibers of 12,000 filaments are continuously treated in an oxidation treatment furnace at 235 ° C. and 255 ° C. circulating heated air at normal pressure with a draw ratio of 2.0, and the specific gravity of the fibers is 1.33. Fiber was obtained.

【００５９】得られた耐炎化繊維を窒素雰囲気で最高温
度８００℃の前炭化炉で延伸比１．０２、次いで最高温
度１４５０℃の炭化炉で延伸比０．９８として焼成し炭
素繊維を得た。The obtained oxidized fiber was fired in a nitrogen atmosphere at a drawing ratio of 1.02 in a pre-carbonization furnace at a maximum temperature of 800 ° C. and then in a carbonization furnace at a maximum temperature of 1450 ° C. at a drawing ratio of 0.98 to obtain carbon fibers. .

【００６０】次いで炭酸アンモニウムの水溶液中で１０
クーロン／ｇ−ＣＦの陽極酸化処理を行った。Next, 10 minutes in an aqueous solution of ammonium carbonate.
Anodizing treatment of Coulomb / g-CF was performed.

【００６１】このようにして得られた炭素繊維の樹脂含
浸・硬化処理したストランドの強度および弾性率はそれ
ぞれ６．８ＧＰａ、３０２ＧＰａと高品質の炭素繊維で
あった。The strands obtained by impregnating and curing the carbon fiber thus obtained with the resin were high-quality carbon fibers of 6.8 GPa and 302 GPa, respectively.

【００６２】（比較例１）実施例１において、原液に水
を添加しない以外は実施例１と同様にして製糸全延伸倍
率１３倍、単繊維繊度１．０デニールのプリカーサーを
得た。未延伸糸および浴延伸糸の膨潤度はそれぞれ１４
０％、１００％であった。前駆体繊維の断面形状は円形
であった。(Comparative Example 1) A precursor having a total drawing ratio of 13 times and a single fiber fineness of 1.0 denier was obtained in the same manner as in Example 1 except that water was not added to the stock solution. The degree of swelling of the undrawn yarn and the bath drawn yarn is 14
0% and 100%. The cross-sectional shape of the precursor fiber was circular.

【００６３】溶剤による溶解試験の結果、円形のまま溶
解は進行したが、繊維半径方向の表層部／内層部の溶解
速度比は０．２９と極めて小さく、溶解速度が半径方向
に実質的に一定ではなく、内外構造差の大きいものであ
った。As a result of the dissolution test using a solvent, the dissolution proceeded in a circular shape, but the dissolution rate ratio of the surface layer / inner layer in the fiber radial direction was extremely small at 0.29, and the dissolution rate was substantially constant in the radial direction. Instead, the difference between the internal and external structures was large.

【００６４】広角Ｘ線による繊維軸方向の結晶配向度は
９３．０％であった。The degree of crystal orientation in the fiber axis direction by wide-angle X-ray was 93.0%.

【００６５】実施例１と同様に焼成して得た炭素繊維の
ストランド強度、弾性率はそれぞれ５．９ＧＰａ、２６
８ＧＰａであり実施例１よりも低強度であった。The strand strength and elastic modulus of the carbon fiber obtained by firing in the same manner as in Example 1 were 5.9 GPa and 26, respectively.
It was 8 GPa, which was lower than that of Example 1.

【００６６】（比較例２）実施例１において、原液に水
を添加せず、また凝固浴のＤＭＳＯ濃度を５０％、温度
を３０℃に変えた以外は実施例１と同様にして、製糸全
延伸倍率１３倍、単繊維繊度１．０デニールのプリカー
サーを得た。繊維断面形状は非円形でそら豆形であっ
た。Comparative Example 2 The same procedure as in Example 1 was repeated except that no water was added to the stock solution, the DMSO concentration in the coagulation bath was changed to 50%, and the temperature was changed to 30 ° C. A precursor having a draw ratio of 13 times and a single fiber fineness of 1.0 denier was obtained. The fiber cross section was non-circular and broad bean-shaped.

【００６７】溶剤による溶解試験の結果、繊維断面で虫
食い状に局部的に溶解が進行するものが多く認められ、
また単繊維間で溶解の程度に差が大きかった。As a result of a dissolution test using a solvent, many of the fibers cross-sectionally dissipate locally in a worm-like manner.
Also, there was a large difference in the degree of dissolution between the single fibers.

【００６８】（比較例３）実施例１と同様にアクリロニ
トリル９８．８モル％とアクリル酸１．２モル％からな
る共重合体を溶剤としてＤＭＳＯを用い溶液重合法によ
り重合し、ポリマ濃度２５％の紡糸原液を得た。重合後
アンモニアガスによる中和は行わなかった。得られた原
液を２軸混練機に導入し、混練機の中間からポリマに対
して３５ｗｔ％になるように水を定量ポンプで連続的に
注入しながら混練機の先端側に設けられた吐出ギヤポン
プにより紡糸原液の量を計量し、紡糸原液の温度を５５
℃に制御後、孔径０．１５ｍｍ、孔数６０００の口金か
ら空気中に押し出し、４ｍｍの３０℃のエアーギャップ
を経て、４０℃にコントロールした３５％ＤＭＳＯの水
溶液からなる凝固浴に導き繊維化し、引き取った凝固糸
を水洗した後、５０〜９０℃の温水中で４段階に分けて
トータル３倍延伸した。未延伸糸および浴延伸糸の膨潤
度はそれぞれ１２５％、１３５％であった。Comparative Example 3 In the same manner as in Example 1, a copolymer consisting of 98.8 mol% of acrylonitrile and 1.2 mol% of acrylic acid was polymerized by a solution polymerization method using DMSO as a solvent to give a polymer concentration of 25%. Was obtained. After the polymerization, neutralization with ammonia gas was not performed. The obtained undiluted solution is introduced into a twin-screw kneader, and a discharge gear pump provided on the tip side of the kneader while continuously injecting water from the middle of the kneader so as to be 35 wt% with respect to the polymer by a constant volume pump. And the temperature of the spinning dope is measured by 55.
After controlling to 0 ° C, the mixture was extruded into the air from a die having a pore size of 0.15 mm and a number of holes of 6000, passed through a 4 mm air gap of 30 ° C, and guided into a coagulation bath consisting of an aqueous solution of 35% DMSO controlled at 40 ° C to form fibers. After the washed coagulated yarn was washed with water, it was stretched three times in warm water at 50 to 90 ° C. in four steps in total. The swelling degrees of the undrawn yarn and the bath drawn yarn were 125% and 135%, respectively.

【００６９】得られた水膨潤状態にある延伸糸にアミノ
変性シリコーンを主体とした油剤を付与し、表面温度１
５０℃の加熱ローラーを用いて定長で乾燥緻密化処理を
行った。An oil agent mainly composed of amino-modified silicone was applied to the obtained water-swollen drawn yarn, and a surface temperature of 1% was applied.
Dry densification treatment was performed at a fixed length using a heating roller at 50 ° C.

【００７０】得られた乾燥緻密化処理糸をさらに４ｋｇ
／ｃｍ² −Ｇの加圧スチーム中で延伸することにより、
製糸全延伸倍率を１３倍とし、単繊維繊度１ｄのアクリ
ル系前駆体繊維を得た。繊維の断面形状は円形であっ
た。A further 4 kg of the obtained dried and densified yarn was added.
/ Cm ² -G by stretching in pressurized steam,
The total draw ratio of the spinning was 13 times, and an acrylic precursor fiber having a single fiber fineness of 1d was obtained. The cross-sectional shape of the fiber was circular.

【００７１】得られた前駆体繊維を６０℃のＤＭＳＯ中
で溶解試験を行った結果、断面形状は円形の状態で溶解
が進行していたが、半径方向の表層部／内層部の溶解速
度比３．７と内外差が大きく、溶解速度が半径方向に実
質的に一定ではないものであった。A dissolution test was performed on the obtained precursor fiber in DMSO at 60 ° C. As a result, the dissolution progressed in a circular cross section, but the dissolution rate ratio of the surface layer / inner layer in the radial direction was determined. The difference between inside and outside was 3.7, and the dissolution rate was not substantially constant in the radial direction.

【００７２】前駆体繊維の広角Ｘ線回折による繊維軸方
向の結晶配向度は９２．７％であった。The degree of crystal orientation of the precursor fiber in the fiber axis direction by wide-angle X-ray diffraction was 92.7%.

【００７３】１２０００フィラメントの前駆体繊維を常
圧の加熱空気を循環する２４５℃と２６５℃の酸化処理
炉で延伸比を１．０として連続的に処理し、繊維比重が
１．３４の耐炎化繊維を得た。Precursor fibers of 12000 filaments are continuously treated in an oxidation treatment furnace at 245 ° C. and 265 ° C. circulating heated air at normal pressure with a draw ratio of 1.0, and are flame-resistant with a fiber specific gravity of 1.34. Fiber was obtained.

【００７４】得られた耐炎化繊維を窒素雰囲気で最高温
度８００℃の前炭化炉で延伸比１．０２、次いで最高温
度１４５０℃の炭化炉で延伸比０．９８として焼成し炭
素繊維を得た。The obtained oxidized fiber was fired in a nitrogen atmosphere at a drawing ratio of 1.02 in a pre-carbonization furnace at a maximum temperature of 800 ° C. and then in a carbonization furnace at a maximum temperature of 1450 ° C. at a drawing ratio of 0.98 to obtain carbon fibers. .

【００７５】次いで炭酸アンモニウムの水溶液中で１０
クーロン／ｇ−ＣＦの陽極酸化処理を行った。Then, the solution was added to an aqueous solution of ammonium carbonate for 10 minutes.
Anodizing treatment of Coulomb / g-CF was performed.

【００７６】このようにして得られた炭素繊維の樹脂含
浸・硬化処理したストランドの強度および弾性率はそれ
ぞれ５．５ＧＰａ、２６５ＧＰａと低強度であった。The strands obtained by impregnating and curing the carbon fibers thus obtained with the resin had low strengths of 5.5 GPa and 265 GPa, respectively.

【００７７】[0077]

【発明の効果】本発明の炭素繊維用前駆体繊維は、従来
の炭素繊維用前駆体繊維にはなかった高緻密でしかも内
外構造差の小さい前駆体繊維であり、これによって高性
能な炭素繊維の製造が可能になる。The precursor fiber for carbon fiber of the present invention is a precursor fiber having a high density and a small difference in inner and outer structures, which has not been obtained in the conventional precursor fiber for carbon fiber. Can be manufactured.

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】広角Ｘ線による配向度が７０％以上、９５
％以下であり、かつ繊維を溶剤で溶解する試験におい
て、単繊維の断面形状が実質的に相似形で溶解が進行
し、その溶解速度が半径方向に実質的に一定であること
を特徴とするアクリル系炭素繊維用前駆体繊維。1. The method according to claim 1, wherein the degree of orientation by wide-angle X-ray is 70% or more,
% Or less, and in a test for dissolving the fiber with a solvent, the dissolution proceeds in a substantially similar cross-sectional shape of the single fiber, and the dissolution rate is substantially constant in the radial direction. Precursor fiber for acrylic carbon fiber. 【請求項２】単繊維断面形状が実質的に円形であること
を特徴とする請求項１記載のアクリル系炭素繊維用前駆
体繊維。2. The precursor fiber for an acrylic carbon fiber according to claim 1, wherein the cross section of the single fiber is substantially circular. 【請求項３】アクリロニトリルを９０ｗｔ％以上含有す
るアクリル系重合体と有機溶剤とからなる溶液に水を添
加し、該重合体に対して１０〜５０ｗｔ％の水を含む紡
糸原液となし、口金孔からいったん４０℃以下の気体雰
囲気中に押し出した後、１０℃以下の凝固浴中に導き、
水洗後の未延伸糸の膨潤度を１５０〜２５０％に調整
し、さらに浴延伸後の膨潤度を１５０％以下に調整する
ことを特徴とするアクリル系炭素繊維用前駆体繊維の製
造方法。3. Water is added to a solution comprising an acrylic polymer containing 90% by weight or more of acrylonitrile and an organic solvent to form a spinning dope containing 10 to 50% by weight of water with respect to the polymer. Once extruded into a gas atmosphere of 40 ° C or less, it is led into a coagulation bath of 10 ° C or less,
A method for producing a precursor fiber for an acrylic carbon fiber, wherein the swelling degree of an undrawn yarn after washing with water is adjusted to 150 to 250%, and the swelling degree after bath drawing is adjusted to 150% or less.