JP5473468B2 - Carbon fiber precursor fiber bundle, method for producing the same, and carbon fiber bundle - Google Patents
Carbon fiber precursor fiber bundle, method for producing the same, and carbon fiber bundle Download PDFInfo
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本発明は、繊維強化複合材料の強化材として使用される炭素繊維束の製造に適したアクリロニトリル系重合体の単繊維からなる炭素繊維前駆体繊維束（以下、単に「前駆体繊維束」と称することがある。）に関する。 The present invention is a carbon fiber precursor fiber bundle (hereinafter, simply referred to as “precursor fiber bundle”) composed of a single fiber of an acrylonitrile-based polymer suitable for production of a carbon fiber bundle used as a reinforcing material for a fiber reinforced composite material. There are things.)
繊維強化複合材料には、強化材として、炭素繊維、ガラス繊維、アラミド繊維等が使用されている。中でも、炭素繊維は、比強度、比弾性率、耐熱性、耐薬品性に優れ、航空機用途、ゴルフシャフトや釣り竿等のスポーツ用途、一般産業用途の繊維強化複合材料の強化材として使用されている。このような繊維強化複合材料は、例えば、以下のようにして製造される。 Carbon fiber, glass fiber, aramid fiber or the like is used as a reinforcing material in the fiber reinforced composite material. Among them, carbon fiber is excellent in specific strength, specific elastic modulus, heat resistance, and chemical resistance, and is used as a reinforcing material for fiber reinforced composite materials for aircraft use, sports use such as golf shafts and fishing rods, and general industrial use. . Such a fiber reinforced composite material is manufactured as follows, for example.
まず、ポリアクリロニトリル系重合体の単繊維からなる前駆体繊維束を、焼成工程（耐炎化工程）にて空気などの酸化性気体中で２００〜３００℃の温度で焼成して耐炎化繊維を得る。次いで、炭素化工程にて不活性雰囲気中で３００〜２０００℃の温度で炭素化して炭素繊維束を得る。そして、この炭素繊維束を、必要に応じて織物等に加工した後、これに樹脂を含浸させ、所定の形状に成形することにより繊維強化複合材料を得る。 First, a precursor fiber bundle made of a single fiber of a polyacrylonitrile-based polymer is baked at a temperature of 200 to 300 ° C. in an oxidizing gas such as air in a baking process (flame-proofing process) to obtain a flame-resistant fiber. . Subsequently, it carbonizes at a temperature of 300-2000 degreeC in inert atmosphere at a carbonization process, and obtains a carbon fiber bundle. And after processing this carbon fiber bundle into textiles etc. as needed, this is impregnated with resin, and a fiber reinforced composite material is obtained by shape | molding in a predetermined shape.
炭素繊維束の製造に用いられる前駆体繊維束には、焼成工程において繊維束がばらけて、繊維束を構成する単繊維が隣接する繊維束に絡まったり、ローラーに巻き付いたりしないように、高い集束性が要求される。しかしながら、集束性の高い前駆体繊維束から得られる炭素繊維束は、その集束性の高さのため、樹脂が含浸しにくいという問題を有していた。 Precursor fiber bundles used in the production of carbon fiber bundles are high so that the fiber bundles are scattered in the firing process and the single fibers constituting the fiber bundles are not entangled with adjacent fiber bundles or wound around rollers. Convergence is required. However, the carbon fiber bundle obtained from the precursor fiber bundle having a high bundling property has a problem that the resin is difficult to be impregnated due to its high bundling property.
また、炭素繊維束を製織して得られる炭素繊維織物は、樹脂を含浸する際に樹脂のボイドが発生しないように、できるだけ目開きの少ない織物とする必要がある。そのために、製織中または製織後に何らかの開繊処理が施される。しかしながら、集束性の高い前駆体繊維束から得られる炭素繊維束は、その集束性の高さのため、開繊しにくいという問題を有していた。さらに、炭素繊維織物は、目空きの少ない均一な織り目が要求されるため、嵩高い炭素繊維束が必要とされていた。 Further, the carbon fiber woven fabric obtained by weaving the carbon fiber bundle needs to be a woven fabric having as few openings as possible so that resin voids are not generated when the resin is impregnated. For this purpose, some opening process is performed during or after weaving. However, the carbon fiber bundle obtained from the precursor fiber bundle having high bundling property has a problem that it is difficult to open due to its high bundling property. Furthermore, since the carbon fiber woven fabric is required to have a uniform weave with little open space, a bulky carbon fiber bundle is required.
本発明者らは、上記のような技術的背景のもと、炭素繊維束と樹脂との複合材の基本特性を向上する対策について種々検討した結果、単繊維の表面形態を制御して、繊維断面の偏平係数を小さく保ちながら、表面しわを大きくすることが非常に有効であることを見出した。 Based on the technical background as described above, the present inventors have studied various measures for improving the basic characteristics of a composite material of a carbon fiber bundle and a resin. It was found that it is very effective to increase the surface wrinkle while keeping the cross-sectional flatness coefficient small.
ここで、炭素繊維または炭素繊維前駆体繊維の断面形状や表面しわの制御の有効性については、特許文献１および２において開示されている。しかしながら、特許文献１および２に開示された技術では、繊維断面の長径と短径との比などで示される断面の偏平度と表面しわとが紡糸条件などによってともに変化し、例えば、樹脂含浸性や開繊性を向上するために表面しわを大きくする製造条件ととると繊維断面の偏平度も大きくなり、炭素繊維束の機械的強度を発現しにくかった。 Here, Patent Documents 1 and 2 disclose the effectiveness of controlling the cross-sectional shape and surface wrinkles of carbon fibers or carbon fiber precursor fibers. However, in the techniques disclosed in Patent Documents 1 and 2, the flatness of the cross section indicated by the ratio of the major axis to the minor axis of the fiber cross section and the surface wrinkle change together depending on the spinning conditions, for example, resin impregnation In addition, if the production conditions are such that the surface wrinkles are increased in order to improve the spreadability, the flatness of the fiber cross section also increases, making it difficult to express the mechanical strength of the carbon fiber bundle.
本発明は、集束性が高く、焼成工程通過性が良好な炭素繊維前駆体繊維束を得ることを目的とする。また、本発明は、樹脂含浸性および開繊性が良好で、機械的強度が高い炭素繊維束を得ることを目的とする。 It is an object of the present invention to obtain a carbon fiber precursor fiber bundle that has high convergence and good baking process passability. Another object of the present invention is to obtain a carbon fiber bundle that has good resin impregnation and spreadability and high mechanical strength.
本発明の第一の要旨は、単繊維の繊維断面の偏平係数が１．１５〜１．３０であり、かつ前記単繊維の粗面係数が１．０３８〜１．０６０である炭素繊維前駆体繊維束にある。 The first gist of the present invention is a carbon fiber precursor in which the flatness of the fiber cross section of the single fiber is 1.15 to 1.30, and the rough surface coefficient of the single fiber is 1.038 to 1.060. It is in the fiber bundle.
本発明の第二の要旨は、前記の炭素繊維前駆体繊維束の製造方法であって、
９５質量％以上のアクリロニトリル単位を含有するアクリロニトリル系重合体の有機溶剤溶液からなる紡糸溶液を、有機溶剤濃度５５〜６８質量％、温度３３〜４０℃の有機溶剤水溶液が投入された第１凝固浴中に吐出して凝固糸とするとともに、前記紡糸原液の吐出線速度の０．８倍以下の速度で、前記第１凝固浴中から前記凝固糸を引き取る工程と、
前記引き取られた凝固糸に対して、前記第１凝固浴と同じ条件の有機溶剤水溶液が投入された第２凝固浴中にて１．５〜２．０倍の延伸を施す工程と、
前記第２凝固浴中で延伸された繊維束に対して、３．０倍以上の湿熱延伸を施す工程と、
前記湿熱延伸された繊維束に対して、シリコーン系油剤の添油処理を行う工程と、
前記添油処理された繊維束を乾燥した後、その繊維束に対して、１．５〜２．５倍のスチーム延伸を施す工程と
を有する炭素繊維前駆体繊維束の製造方法にある。
The second gist of the present invention is a method for producing the carbon fiber precursor fiber bundle,
A first coagulation bath in which a spinning solution comprising an organic solvent solution of an acrylonitrile polymer containing 95% by mass or more of an acrylonitrile unit is charged with an organic solvent aqueous solution having an organic solvent concentration of 55 to 68% by mass and a temperature of 33 to 40 ° C. Discharging into the coagulated yarn, and drawing the coagulated yarn from the first coagulation bath at a rate of 0.8 times or less the discharge linear speed of the spinning dope;
A step of stretching 1.5 to 2.0 times in the second coagulation bath in which the organic solvent aqueous solution having the same condition as the first coagulation bath is charged with respect to the taken-up coagulated yarn;
A step of subjecting the fiber bundle drawn in the second coagulation bath to wet heat drawing of 3.0 times or more;
A process of adding a silicone-based oil to the wet-heat-stretched fiber bundle;
After drying the oil-treated fiber bundle, the method includes the step of subjecting the fiber bundle to steam stretching of 1.5 to 2.5 times, and a carbon fiber precursor fiber bundle manufacturing method.
本発明の第三の要旨は、前記の炭素繊維前駆体繊維束を焼成して得られる炭素繊維束であって、前記炭素繊維束を構成する単繊維の繊維断面の偏平係数が１．２０〜１．３５であり、かつ前記炭素繊維束を構成する単繊維の粗面係数が１．０３０〜１．０６０である炭素繊維束にある。 The third gist of the present invention is a carbon fiber bundle obtained by firing the carbon fiber precursor fiber bundle, and the flatness of the fiber cross section of the single fiber constituting the carbon fiber bundle is 1.20. The carbon fiber bundle is 1.35 and the single fiber constituting the carbon fiber bundle has a rough surface coefficient of 1.030 to 1.060.
本発明によれば、集束性が高く、焼成工程通過性が良好な炭素繊維前駆体繊維束を得ることができ、また、樹脂含浸性および開繊性が良好で、機械的強度が高い炭素繊維束を得ることができる。 According to the present invention, it is possible to obtain a carbon fiber precursor fiber bundle having high bundling property and good firing process passability, and good carbon impregnation and spreadability and high mechanical strength. You can get a bunch.
以下、本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail.
＜炭素繊維前駆体繊維束＞
まず、本発明の炭素繊維前駆体繊維束について説明する。本発明の炭素繊維前駆体繊維束は、例えば、複数のアクリロニトリル系重合体の単繊維を束ねたトウである。
<Carbon fiber precursor fiber bundle>
First, the carbon fiber precursor fiber bundle of the present invention will be described. The carbon fiber precursor fiber bundle of the present invention is, for example, a tow obtained by bundling a plurality of acrylonitrile polymer single fibers.
（アクリロニトリル系重合体）
アクリロニトリル系重合体としては、アクリロニトリル単位を９５質量％以上含有する重合体が、その炭素繊維前駆体繊維束を焼成して得られる炭素繊維束の強度発現性の点で好ましい。アクリロニトリル系重合体は、アクリロニトリルと、必要に応じてこれと共重合しうる単量体とを、水溶液中におけるレドックス重合、不均一系における懸濁重合、分散剤を使用した乳化重合などによって得ることができる。
(Acrylonitrile polymer)
As the acrylonitrile-based polymer, a polymer containing 95% by mass or more of an acrylonitrile unit is preferable in terms of strength development of a carbon fiber bundle obtained by firing the carbon fiber precursor fiber bundle. Acrylonitrile polymer is obtained by redox polymerization in aqueous solution, suspension polymerization in heterogeneous system, emulsion polymerization using a dispersant, etc. Can do.
アクリロニトリルと共重合しうる単量体としては、例えば、メチル（メタ）アクリレート、エチル（メタ）アクリレート、プロピル（メタ）アクリレート、ブチル（メタ）アクリレート、ヘキシル（メタ）アクリレート等の（メタ）アクリル酸エステル類；塩化ビニル、臭化ビニル、塩化ビニリデン等のハロゲン化ビニル類；（メタ）アクリル酸、イタコン酸、クロトン酸等の不飽和カルボン酸類およびそれらの塩類；マレイン酸イミド、フェニルマレイミド、（メタ）アクリルアミド、スチレン、α−メチルスチレン、酢酸ビニル；スチレンスルホン酸ナトリウム、アリルスルホン酸ナトリウム、β−スチレンスルホン酸ナトリウム、メタアリルスルホン酸ナトリウム等のスルホン基を含む重合性不飽和単量体；２−ビニルピリジン、２−メチル−５−ビニルピリジン等のピリジン基を含む重合性不飽和単量体等が挙げられる。 Examples of monomers that can be copolymerized with acrylonitrile include (meth) acrylic acid such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and hexyl (meth) acrylate. Esters; vinyl halides such as vinyl chloride, vinyl bromide and vinylidene chloride; unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid and crotonic acid and their salts; maleic imide, phenylmaleimide, (meta ) Acrylamide, styrene, α-methylstyrene, vinyl acetate; polymerizable unsaturated monomer containing a sulfone group such as sodium styrenesulfonate, sodium allylsulfonate, sodium β-styrenesulfonate, sodium methallylsulfonate; 2 -Vinylpyridine, 2-me Examples thereof include polymerizable unsaturated monomers containing a pyridine group such as til-5-vinylpyridine.
より好ましいアクリロニトリル系重合体は、９５質量％以上のアクリロニトリル単位と、０．５〜４．０質量％のアクリルアミド単位とを含有するアクリロニトリル系重合体である。アクリルアミド単位を４．０質量％以下とすることで、炭素繊維前駆体繊維束を焼成して得られる炭素繊維束の機械的強度が高くなる。また、アクリルアミド単位を０．５質量％以上とすることで、アクリロニトリル系重合体の紡糸原液への溶解性が高まり、紡糸口金を通して凝固浴中に吐出させた際の凝固速度が速くなり、紡糸安定性も向上する。アクリロニトリル単位は、９５質量％以上、９８質量％以下が好ましい。アクリルアミド単位は、１．０質量％以上、４．０質量％以下が好ましい。 A more preferred acrylonitrile polymer is an acrylonitrile polymer containing 95% by mass or more of acrylonitrile units and 0.5 to 4.0% by mass of acrylamide units. By setting the acrylamide unit to 4.0% by mass or less, the mechanical strength of the carbon fiber bundle obtained by firing the carbon fiber precursor fiber bundle is increased. In addition, by setting the acrylamide unit to 0.5% by mass or more, the solubility of the acrylonitrile polymer in the spinning dope increases, and the coagulation speed when discharged through the spinneret into the coagulation bath increases, thereby stabilizing the spinning. Also improves. The acrylonitrile unit is preferably 95% by mass or more and 98% by mass or less. The acrylamide unit is preferably 1.0% by mass or more and 4.0% by mass or less.
（偏平係数と粗面係数）
本発明では、単繊維の繊維断面の偏平係数を１．１５〜１．３０とする。偏平係数が１．３０を超えると、前駆体繊維束の集束性が低下し、焼成工程通過性が悪化する。また、偏平係数が大きいことは、紡糸工程で繊維表層の凝固が速いために緻密なスキン層が形成されて繊維内部の凝固が遅延し、細孔の多い繊維となることに起因する。したがって、その前駆体繊維束を焼成して得られる炭素繊維束のストランド強度が著しく低下する。一方、偏平係数が１．１５未満の場合には、前駆体繊維束を焼成して得られる炭素繊維束の機械的強度は高くなるが、単繊維間の空隙が減少するために、炭素繊維束の樹脂含浸性および開繊性が悪くなる。単繊維の繊維断面の偏平係数は、１．２０〜１．３０が好ましい。
(Flatness coefficient and rough surface coefficient)
In this invention, the flatness coefficient of the fiber cross section of a single fiber shall be 1.15-1.30. When the flatness coefficient exceeds 1.30, the convergence property of the precursor fiber bundle is lowered, and the firing process passability is deteriorated. Also, the large flatness factor is attributed to the fact that the fiber surface layer is rapidly solidified in the spinning process, so that a dense skin layer is formed and the solidification inside the fiber is delayed, resulting in a fiber with many pores. Therefore, the strand strength of the carbon fiber bundle obtained by firing the precursor fiber bundle is significantly reduced. On the other hand, when the flatness coefficient is less than 1.15, the mechanical strength of the carbon fiber bundle obtained by firing the precursor fiber bundle is increased, but the voids between the single fibers are reduced. The resin impregnation property and the fiber opening property are deteriorated. As for the flatness coefficient of the fiber cross section of a single fiber, 1.20-1.30 are preferable.
また、本発明では、単繊維表面のしわの大きさの指標となる粗面係数を１．０３８〜１．０６０とする。粗面係数が１．０３８未満の場合には、単繊維間の空隙が減少するために、焼成して得られる炭素繊維束の樹脂含浸性および開繊性が悪くなる。一方、粗面係数が１．０６０を超えると、前駆体繊維束の集束性が低下し、焼成工程通過性が悪化する。また、焼成して得られる炭素繊維束のストランド強度が著しく低下する。単繊維の粗面係数は、１．０４０〜１．０５５が好ましい。 Moreover, in this invention, the rough surface coefficient used as the parameter | index of the magnitude | size of the wrinkle of the single fiber surface shall be 1.038-1.060. When the rough surface coefficient is less than 1.038, voids between the single fibers are reduced, so that the resin impregnation property and the fiber opening property of the carbon fiber bundle obtained by firing are deteriorated. On the other hand, when the rough surface coefficient exceeds 1.060, the converging property of the precursor fiber bundle is lowered, and the passability of the firing process is deteriorated. Moreover, the strand strength of the carbon fiber bundle obtained by firing is significantly reduced. The rough surface coefficient of the single fiber is preferably 1.040 to 1.055.
炭素繊維前駆体繊維束の単繊維の偏平係数は、例えば、凝固浴の有機溶剤濃度や浴温度を変えることによって、１．１５〜１．３０の範囲に調整することができる。しかし、従来の方法では、得られる繊維束の単繊維の粗面係数は、偏平係数の変化に伴って単調に変化して１．０３８未満となり、粗面係数と偏平係数のいずれもが好適な範囲にある繊維束を得ることができなかった。ところが、後述する本発明の方法により、単繊維の繊維断面の偏平係数が１．１５〜１．３０であり、かつ前記単繊維の粗面係数が１．０３８〜１．０６０である炭素繊維前駆体繊維束を製造することができるようになった。 The flatness coefficient of the single fiber of the carbon fiber precursor fiber bundle can be adjusted to the range of 1.15 to 1.30, for example, by changing the concentration of the organic solvent in the coagulation bath and the bath temperature. However, in the conventional method, the rough surface coefficient of the single fiber of the obtained fiber bundle changes monotonously with the change of the flatness coefficient to be less than 1.038, and both the rough surface coefficient and the flatness coefficient are suitable. A fiber bundle in the range could not be obtained. However, by the method of the present invention described later, a carbon fiber precursor in which the flatness of the fiber cross section of the single fiber is 1.15 to 1.30 and the rough surface coefficient of the single fiber is 1.038 to 1.060. It became possible to manufacture body fiber bundles.
そして、本発明者らは、単繊維の繊維断面の偏平係数が１．１５〜１．３０であり、かつ単繊維の粗面係数が１．０３８〜１．０６０である前駆体繊維束であれば、焼成工程通過性を損なうことなく、樹脂含浸性および開繊性が良好で、機械的強度が高い炭素繊維束が得られることを見出した。この前駆体繊維束は、一般的な紡糸法で得られる前駆体繊維束と同等の偏平係数をもちながら、粗面係数が大きいことを特徴とする。 The inventors of the present invention may be a precursor fiber bundle in which the flatness of the fiber cross section of the single fiber is 1.15 to 1.30 and the rough surface coefficient of the single fiber is 1.038 to 1.060. For example, it has been found that a carbon fiber bundle having good resin impregnation property and fiber opening property and high mechanical strength can be obtained without impairing the passability of the firing process. This precursor fiber bundle is characterized in that it has a flat coefficient equivalent to that of a precursor fiber bundle obtained by a general spinning method and has a large rough surface coefficient.
（偏平係数および粗面係数の計測方法）
単繊維の断面形状パラメーターである偏平係数および粗面係数は、以下の方法で計測される。
(Measurement method of flatness coefficient and rough surface coefficient)
The flatness coefficient and the rough surface coefficient, which are cross-sectional shape parameters of the single fiber, are measured by the following method.
前駆体繊維束または炭素繊維束をエポキシ樹脂などで包埋したのち、研磨機により繊維軸に対して直角に断面加工する。研磨機は特に制限はなく、（株）マルトー製ＭＬ−１１０Ｎ（商品名）などを用いることができる。研磨の手順としては、＃８００および＃１５００の研磨紙で粗研磨した後、ポリッシングクロスなどで仕上げ研磨する。次いで、プラズマエッチング処理を施した後、さらにＡｕを約１０ｎｍの厚さにスパッタリングして、走査型電子顕微鏡によって１０００倍で観察して画像を得る。プラズマエッチング装置は特に制限はないが、例えば、日本電子データム（株）製ＪＰ−１７０（商品名）などの電子顕微鏡用エッチング装置が好ましい。得られた画像の計測は画像計測ソフトウェアを用いて行い、単繊維の断面の外形をトレースしたときの周長Ｌおよびその面積Ａ、さらに、断面の長径Ｄ１および短径Ｄ２を計測した。これらの値を用いて、次式により偏平係数および粗面係数を算出する。用いる画像計測ソフトウェアは特に制限はなく、例えば、日本ローパー（株）Ｉｍａｇｅ−Ｐｒｏ ＰＬＵＳ（商品名）などを用いることができる。 After the precursor fiber bundle or the carbon fiber bundle is embedded with an epoxy resin or the like, a cross section is processed at a right angle to the fiber axis by a polishing machine. The polishing machine is not particularly limited, and ML-110N (trade name) manufactured by Maruto Corporation can be used. As a polishing procedure, after rough polishing with # 800 and # 1500 polishing paper, finish polishing is performed with a polishing cloth or the like. Next, after performing a plasma etching process, Au is further sputtered to a thickness of about 10 nm, and an image is obtained by observing at 1000 times with a scanning electron microscope. Although there is no restriction | limiting in particular in a plasma etching apparatus, For example, the etching apparatus for electron microscopes, such as JEOL datum Co., Ltd. product JP-170 (brand name), are preferable. Measurement of the obtained image was performed using image measurement software, and the circumference L and its area A when the outer shape of the cross section of the single fiber was traced, and the major axis D1 and minor axis D2 of the cross section were measured. Using these values, the flatness coefficient and the rough surface coefficient are calculated by the following equations. The image measurement software used is not particularly limited, and for example, Nippon Roper Corporation Image-Pro PLUS (trade name) can be used.
偏平係数＝Ｄ１／Ｄ２
粗面係数＝（Ｌ／π）／（４×Ａ／π）1/2
偏平係数は、単繊維の繊維断面の長径と短径の比であり、繊維断面の偏平度の指標となる値である。また、粗面係数は、単繊維の繊維断面の周囲長から円換算した直径と実測面積から円換算した直径との比であり、繊維表面の凹凸（しわ）の指標となる値である。５０本以上の単繊維についてこれらの値を計測し、平均値を求める。
Flatness factor = D1 / D2
Roughness coefficient = (L / π) / (4 × A / π) 1/2
The flatness coefficient is the ratio of the major axis to the minor axis of the fiber cross section of a single fiber, and is a value that serves as an index of the flatness of the fiber cross section. The rough surface coefficient is a ratio of the diameter converted from the circumference of the fiber cross section of the single fiber to the diameter converted from the measured area into a circle, and is a value serving as an index of the unevenness (wrinkles) on the fiber surface. These values are measured for 50 or more single fibers, and an average value is obtained.
＜炭素繊維前駆体繊維束の製造方法＞
次に、本発明の炭素繊維前駆体繊維束の製造方法について説明する。本発明の炭素繊維前駆体繊維束は、例えば、以下のようにして製造することができる。
<Method for producing carbon fiber precursor fiber bundle>
Next, the manufacturing method of the carbon fiber precursor fiber bundle of this invention is demonstrated. The carbon fiber precursor fiber bundle of the present invention can be produced, for example, as follows.
まず、アクリロニトリル系重合体の有機溶剤溶液からなる紡糸原液を、紡糸口金を通して、有機溶剤濃度５５〜６８質量％、温度３３〜４０℃の有機溶剤水溶液が投入された第１凝固浴中に吐出して凝固糸にするとともに、紡糸原液の吐出線速度の０．８倍以下の速度で、第１凝固浴中から凝固糸を引き取る。 First, a spinning stock solution composed of an organic solvent solution of an acrylonitrile polymer is discharged through a spinneret into a first coagulation bath in which an organic solvent aqueous solution having an organic solvent concentration of 55 to 68% by mass and a temperature of 33 to 40 ° C. is charged. The coagulated yarn is taken out from the first coagulation bath at a speed of 0.8 times or less the discharge linear velocity of the spinning dope.
紡糸原液の溶媒として用いる有機溶剤としては、例えば、ジメチルアセトアミド、ジメチルスルホキシド、ジメチルホルムアミド等が挙げられる。中でも、ジメチルアセトアミドは、溶剤の加水分解による性状の悪化が少なく、良好な紡糸性を与えるので、好適に用いられる。紡糸原液におけるアクリロニトリル系重合体の濃度は、紡糸安定性および得られる前駆体繊維の緻密性の観点から、１８〜２４質量％が好ましい。 Examples of the organic solvent used as the solvent for the spinning dope include dimethylacetamide, dimethylsulfoxide, dimethylformamide, and the like. Among them, dimethylacetamide is preferably used because it is less deteriorated due to hydrolysis of the solvent and gives good spinnability. The concentration of the acrylonitrile-based polymer in the spinning dope is preferably 18 to 24% by mass from the viewpoint of spinning stability and the denseness of the resulting precursor fiber.
第一凝固浴中の有機溶剤水溶液に含まれる有機溶剤としては、例えば、例えば、ジメチルアセトアミド、ジメチルスルホキシド、ジメチルホルムアミド等が挙げられる。第一凝固浴中の有機溶剤水溶液に含まれる有機溶剤は、紡糸原液の溶媒として用いる有機溶剤と同じであることが好ましい。 Examples of the organic solvent contained in the organic solvent aqueous solution in the first coagulation bath include dimethylacetamide, dimethylsulfoxide, dimethylformamide, and the like. The organic solvent contained in the organic solvent aqueous solution in the first coagulation bath is preferably the same as the organic solvent used as the solvent for the spinning dope.
紡糸原液を押し出すための紡糸口金としては、アクリロニトリル系重合体の単繊維の一般的な太さである１．０８デニール（１．２ｄｔｅｘ）程度のアクリロニトリル系重合体の単繊維を製造する際の孔径、すなわち１５〜１００μｍの孔径のノズル孔を有する紡糸口金を使用することができる。紡糸口金の孔数は、紡糸安定性および工程での乾燥負荷の観点から、１，０００〜１２，０００が好ましく、より好ましくは１，０００〜６，０００、さらに好ましくは１，０００〜３，０００である。 As the spinneret for extruding the spinning dope, the pore diameter when producing single fibers of acrylonitrile polymer of about 1.08 denier (1.2 dtex), which is the general thickness of single fiber of acrylonitrile polymer That is, a spinneret having a nozzle hole having a diameter of 15 to 100 μm can be used. The number of holes in the spinneret is preferably 1,000 to 12,000, more preferably 1,000 to 6,000, and still more preferably 1,000 to 3, from the viewpoint of spinning stability and drying load in the process. 000.
第１凝固浴中から凝固糸を引き取る速度を、紡糸原液の吐出線速度の０．８倍以下とすることで、良好な紡糸性を維持することができる。第１凝固浴中から凝固糸を引き取る速度は、紡糸原液の吐出線速度の０．４倍以上０．８倍以下とすることが好ましい。 By setting the speed at which the coagulated yarn is taken out from the first coagulation bath to be 0.8 times or less the discharge linear speed of the spinning dope, good spinnability can be maintained. The speed at which the coagulated yarn is taken out from the first coagulation bath is preferably 0.4 to 0.8 times the discharge linear speed of the spinning dope.
第１凝固浴から引き上げられた凝固糸は、凝固糸が含有する液体中の有機溶剤の濃度が、第１凝固浴中の有機溶剤の濃度を超えているので、凝固糸の表面だけが凝固した半凝固状態にある凝固糸になり、次工程の第２凝固浴中での延伸性が良好な凝固糸になる。 In the coagulated yarn pulled up from the first coagulation bath, the concentration of the organic solvent in the liquid contained in the coagulated yarn exceeds the concentration of the organic solvent in the first coagulation bath, so that only the surface of the coagulated yarn coagulated. It becomes a coagulated yarn in a semi-solidified state, and becomes a coagulated yarn having good stretchability in the second coagulation bath in the next step.
次いで、第１凝固浴から引き取られた凝固糸を、第１凝固浴と同じ条件の有機溶剤水溶液が投入された第２凝固浴中にて１．５〜２．０倍に延伸する。第１凝固浴から引き取られた凝固糸は、凝固液を含んだまま膨潤状態にあり、空気中で延伸することも可能であるが、この凝固糸を第２凝固浴中で延伸する手段をとることにより、凝固糸の凝固を促進させることができ、また延伸工程での温度制御も容易になる。 Next, the coagulated yarn taken out from the first coagulation bath is stretched 1.5 to 2.0 times in the second coagulation bath in which an organic solvent aqueous solution having the same conditions as the first coagulation bath is charged. The coagulated yarn taken from the first coagulation bath is in a swollen state containing the coagulation liquid and can be drawn in the air, but means for drawing the coagulated yarn in the second coagulation bath is taken. As a result, solidification of the coagulated yarn can be promoted, and temperature control in the drawing process is facilitated.
また、第１凝固浴と第２凝固浴の有機溶剤の濃度を同じにし、第１凝固浴と第２凝固浴の温度を同じにし、さらには紡糸原液の有機溶剤と第１凝固浴に用いる有機溶剤と第２凝固浴に用いる有機溶剤とを同じにすることにより、第１凝固浴および第２凝固浴の調製が容易となり、しかも有機溶剤回収上でのメリットも生ずる。特に、アクリロニトリル系重合体のジメチルアセトアミド溶液からなる紡糸原液を用い、第１凝固浴および第２凝固浴に同じ温度および濃度のジメチルアセトアミド水溶液を用いることで、繊維断面の偏平係数が１．１５〜１．３５の単繊維の製造を容易に行えるようになる。 Further, the concentration of the organic solvent in the first coagulation bath and the second coagulation bath is made the same, the temperature of the first coagulation bath and the second coagulation bath are made the same, and further, the organic solvent used for the spinning solution and the organic used in the first coagulation bath By making the solvent and the organic solvent used in the second coagulation bath the same, the preparation of the first coagulation bath and the second coagulation bath is facilitated, and there is also a merit in collecting the organic solvent. In particular, by using a spinning stock solution composed of a dimethylacetamide solution of an acrylonitrile-based polymer, and using a dimethylacetamide aqueous solution having the same temperature and concentration in the first coagulation bath and the second coagulation bath, the flatness coefficient of the fiber cross section is 1.15. 1.35 single fiber can be easily manufactured.
なお、第１凝固浴と第２凝固浴の有機溶剤の濃度を低くすることによって、繊維断面の偏平係数が大きい単繊維が得られる。一方、第１凝固浴と第２凝固浴の有機溶剤の濃度を高くすることによって、繊維断面の偏平係数が１．０に近い単繊維が得られる。 In addition, the single fiber with a large flatness coefficient of a fiber cross section is obtained by making low the density | concentration of the organic solvent of a 1st coagulation bath and a 2nd coagulation bath. On the other hand, by increasing the concentration of the organic solvent in the first coagulation bath and the second coagulation bath, a single fiber having a fiber cross-section flatness coefficient close to 1.0 can be obtained.
第２凝固浴中での延伸倍率は、１．５〜２．０倍とする。第２凝固浴中での延伸倍率を１．５倍以上とすることで、均一に配向した繊維が得られるようになる。また、第２凝固浴中での延伸倍率を２．０倍以下とすることで、単繊維切れが発生し難くなり、紡糸安定性が向上し、その後の湿熱延伸工程での延伸性が良好になる。第２凝固浴中での延伸倍率は、１．６〜２．０倍とすることが好ましい。 The draw ratio in the second coagulation bath is 1.5 to 2.0 times. By setting the draw ratio in the second coagulation bath to 1.5 times or more, uniformly oriented fibers can be obtained. Moreover, by setting the draw ratio in the second coagulation bath to 2.0 times or less, it becomes difficult for single fiber breakage to occur, the spinning stability is improved, and the drawability in the subsequent wet heat drawing step is good. Become. The draw ratio in the second coagulation bath is preferably 1.6 to 2.0 times.
次いで、第２凝固浴中での延伸をされた繊維束に対して３．０倍以上の湿熱延伸を行う。この湿熱延伸は、第２凝固浴中での延伸を終えた膨潤状態にある繊維束における繊維の配向性を高めるためのものであり、繊維束を水洗に付しながらの延伸または熱水中での延伸によって行われる。湿熱延伸の倍率は、高生産性および繊維の配向向上の観点から、３倍以上とするが、３．０倍以上４．０倍以下が好ましい。 Next, wet heat drawing of 3.0 times or more is performed on the fiber bundle drawn in the second coagulation bath. This wet heat stretching is for enhancing the orientation of the fiber in the swollen fiber bundle that has been stretched in the second coagulation bath, and the fiber bundle is stretched while being washed or in hot water. This is done by stretching. The ratio of wet heat stretching is 3 times or more from the viewpoint of high productivity and fiber orientation improvement, but preferably 3.0 times or more and 4.0 times or less.
次いで、この繊維束に対してシリコーン系油剤の添油処理を行う。シリコーン系油剤としては、例えば、アミノ変性シリコーン、エポキシ変性シリコーン、ポリエーテル変性シリコーン等の一般的なシリコーン系油剤や低シリコーン系油剤を用いることができる。シリコーン系油剤の濃度は、０．４〜１．５質量％に調整されることが好ましく、０．８〜１．２質量％に調製されることがより好ましい。 Next, a silicone oil additive is added to the fiber bundle. As the silicone-based oil agent, for example, general silicone-based oil agents such as amino-modified silicone, epoxy-modified silicone, and polyether-modified silicone, and low silicone-based oil agents can be used. It is preferable that the density | concentration of a silicone type oil agent is adjusted to 0.4-1.5 mass%, and it is more preferable to adjust to 0.8-1.2 mass%.
次いで、添油処理された繊維束を乾燥し、さらにスチーム延伸機で１．５〜２．５倍（好ましくは１．８〜２．５倍）のスチーム延伸を行う。そして、この繊維束に対してタッチロールで水分率の調整を行い、続いてエアーを吹き付けて交絡を施すことで、炭素繊維前駆体繊維束を得ることができる。 Next, the fiber bundle subjected to the oil addition treatment is dried, and further, steam stretching is performed 1.5 to 2.5 times (preferably 1.8 to 2.5 times) with a steam stretching machine. And a carbon fiber precursor fiber bundle can be obtained by adjusting a moisture content with a touch roll with respect to this fiber bundle, and then spraying air and performing confounding.
（湿熱延伸糸の膨潤度）
本発明では、湿熱延伸を施した後の乾燥前の繊維束における膨潤度は、９０質量％以下であることが好ましい。湿熱延伸糸の膨潤度が９０質量％以下にある繊維束は、表層部と繊維内部とが均一に配向していることを意味する。例えば、第１凝固浴中での凝固糸の製造の際の「凝固糸の引取り速度／ノズルからの紡糸原液の吐出線速度」を下げることによって、第１凝固浴中での凝固糸の凝固を均一なものにした後、これを第２凝固浴中にて延伸することにより、内部まで均一に配向することができる。これによって、湿熱延伸糸の膨潤度を９０質量％以下とすることができる。湿熱延伸糸の膨潤度は、７５質量％以上９０質量％以下であることがより好ましい。
(Swelling degree of wet heat drawn yarn)
In this invention, it is preferable that the swelling degree in the fiber bundle before drying after performing wet heat drawing is 90 mass% or less. A fiber bundle in which the degree of swelling of the wet heat drawn yarn is 90% by mass or less means that the surface layer portion and the inside of the fiber are uniformly oriented. For example, the coagulation of the coagulated yarn in the first coagulation bath is reduced by lowering “the take-up speed of the coagulated yarn / the discharge linear speed of the spinning dope from the nozzle” in the production of the coagulated yarn in the first coagulation bath. Can be uniformly oriented to the inside by stretching it in the second coagulation bath. Thereby, the swelling degree of the wet heat drawn yarn can be 90% by mass or less. The swelling degree of the wet heat drawn yarn is more preferably 75% by mass or more and 90% by mass or less.
一方、第１凝固浴中での凝固糸の製造の際の「凝固糸の引取り速度／ノズルからの紡糸原液の吐出線速度」を高くすると、第１凝固浴中での凝固糸の凝固と延伸とが同時に起こるため、第１凝固浴中での凝固糸の凝固が不均一になりやすい。したがって、これを第２凝固浴中で延伸する工程をとっても、湿熱延伸を施した後の乾燥前の膨潤繊維束は膨潤度の高いものになってしまい、繊維内部まで均一に配向した繊維にはならない場合がある。そのため、前駆体繊維を焼成して得られる炭素繊維束の機械的強度発現性が低下する場合がある。 On the other hand, if the “coagulated yarn take-up speed / the discharge linear velocity of the spinning dope from the nozzle” in the production of the coagulated yarn in the first coagulation bath is increased, the coagulation of the coagulated yarn in the first coagulation bath is increased. Since stretching occurs simultaneously, coagulation of the coagulated yarn in the first coagulation bath tends to be non-uniform. Therefore, even if the step of stretching this in the second coagulation bath is taken, the swollen fiber bundle before drying after the wet heat stretching becomes high in the degree of swelling, and the fibers uniformly oriented to the inside of the fiber It may not be possible. Therefore, the mechanical strength expression property of the carbon fiber bundle obtained by firing the precursor fiber may decrease.
湿熱延伸糸の膨潤度は、膨潤状態にある繊維束の付着液を遠心分離機（３０００ｒｐｍ、１５分）によって除去した後の質量ｗと、これを１０５℃×２時間の熱風乾燥機で乾燥した後の質量ｗ０とにより、膨潤度（質量％）＝（ｗ−ｗ０）×１００／ｗ０によって求めた数値である。 The degree of swelling of the wet heat drawn yarn was determined by removing the adhering solution of the fiber bundle in the swollen state with a centrifugal separator (3000 rpm, 15 minutes) and drying it with a hot air dryer at 105 ° C. × 2 hours. It is the numerical value calculated | required by swelling degree (mass%) = (w-w0) x100 / w0 by mass w0 after.
＜炭素繊維束＞
次に、本発明の炭素繊維束について説明する。本発明の炭素繊維束は、炭素繊維束を構成する単繊維の繊維断面の偏平係数が１．２０〜１．３５であり、かつ炭素繊維束を構成する単繊維の粗面係数が１．０３０〜１．０６０である。このような炭素繊維束は、樹脂含浸性および開繊性が良好で、機械的強度が高いので、繊維強化複合材料の強化材として好適に用いられる。炭素繊維束を構成する単繊維の繊維断面の偏平係数は、１．２５〜１．３５が好ましい。炭素繊維束を構成する単繊維の粗面係数は、１．０３０〜１．０５５が好ましい。
<Carbon fiber bundle>
Next, the carbon fiber bundle of the present invention will be described. In the carbon fiber bundle of the present invention, the flatness coefficient of the fiber cross section of the single fiber constituting the carbon fiber bundle is 1.20 to 1.35, and the rough surface coefficient of the single fiber constituting the carbon fiber bundle is 1.030. ~ 1.060. Such a carbon fiber bundle is suitable for use as a reinforcing material of a fiber-reinforced composite material because it has good resin impregnation and spreadability and high mechanical strength. As for the flatness coefficient of the fiber cross section of the single fiber which comprises a carbon fiber bundle, 1.25-1.35 are preferable. The rough surface coefficient of the single fiber constituting the carbon fiber bundle is preferably 1.030 to 1.055.
本発明の炭素繊維束は、ポリアクリロニトリル系炭素繊維における通常の焼成工程により、上述の前駆体繊維束を焼成することで製造することができる。すなわち、前駆体繊維束を、空気中２３０〜２６０℃の熱風循環式耐炎化炉にて３０〜６０分間処理して耐炎化繊維束とし、次いで、耐炎繊維束を、窒素雰囲気下最高温度８００℃程度で１〜２分間処理し、さらに同雰囲気下で最高温度が１０００〜２０００℃の高温熱処理炉にて約１〜２分処理する。その後、繊維強化複合材料の強度発現のために、炭素繊維束の表面に電解処理を施し、炭素繊維用サイズ剤を付与してもよい。 The carbon fiber bundle of this invention can be manufactured by baking the above-mentioned precursor fiber bundle by the normal baking process in a polyacrylonitrile-type carbon fiber. That is, the precursor fiber bundle is treated in a hot air circulation type flameproofing furnace at 230 to 260 ° C. in air for 30 to 60 minutes to form a flameproof fiber bundle, and then the flame resistant fiber bundle is heated to a maximum temperature of 800 ° C. in a nitrogen atmosphere. The treatment is performed for about 1 to 2 minutes, and further in the same atmosphere, the treatment is carried out for about 1 to 2 minutes in a high temperature heat treatment furnace having a maximum temperature of 1000 to 2000 ° C. Thereafter, in order to develop the strength of the fiber-reinforced composite material, the surface of the carbon fiber bundle may be subjected to electrolytic treatment to give a carbon fiber sizing agent.
以下、実施例により本発明を詳しく説明する。なお、前駆体繊維束または炭素繊維束の断面形状パラメーターの測定は、以下の方法によって行った。 Hereinafter, the present invention will be described in detail by way of examples. In addition, the measurement of the cross-sectional shape parameter of the precursor fiber bundle or the carbon fiber bundle was performed by the following method.
（集束性）
集束性は前駆体繊維束の紡糸工程の最終ロール、すなわち前駆体繊維束をボビンに巻き取る直前のロール上での前駆体繊維束の状態を観察し、下記の基準で評価した。
○：集束しており、トウ幅が一定で、隣接する繊維束と接触しない。
△：ほぼ集束しているが、トウ幅が一定ではない、あるいはトウ幅が広い。
×：繊維束中に空間があり、集束していない。
(Focusing property)
The bundling property was evaluated according to the following criteria by observing the state of the precursor fiber bundle on the final roll in the spinning process of the precursor fiber bundle, that is, the roll immediately before winding the precursor fiber bundle on the bobbin.
○: Converged, constant tow width, and not in contact with adjacent fiber bundle.
Δ: Converged substantially, but the tow width is not constant or the tow width is wide.
X: There is a space in the fiber bundle and it is not focused.
（断面形状パラメーター）
前駆体繊維束または炭素繊維束を室温硬化型エポキシ樹脂で包埋した後、研磨機（（株）マルトー製、商品名：ＭＬ−１１０Ｎ）により繊維軸に対して直角に断面加工した。次いで、プラズマエッチング装置（日本電子データム（株）製、商品名：ＪＰ−１７０）により出力５０Ｗの条件で５分間プラズマエッチング処理を施した後、さらに、イオンコーター（日本電子データム（株）製、商品名：ＪＦＣ−１１００）によりＡｕを約１０ｎｍの厚さにスパッタリングした。得られた試験片を走査型電子顕微鏡（日本電子（株）製、商品名：ＪＳＭ−６０６０Ａ）によって１０００倍で観察した画像を得た。得られた画像について、画像計測ソフトウェア（日本ローパー（株）製、商品名：Ｉｍａｇｅ−Ｐｒｏ ＰＬＵＳ）により、単繊維の断面の外形をトレースして、周長Ｌおよびその面積Ａ、さらに断面の長径（最大フェレ径）Ｄ１および短径（最小フェレ径）Ｄ２を計測した。これらの値を用いて、次式により偏平係数および粗面係数を算出した。５０本以上の単繊維についてこれらの値を計測し、それぞれ平均値を求めた。
(Cross section shape parameter)
The precursor fiber bundle or the carbon fiber bundle was embedded with a room temperature curable epoxy resin, and then cross-sectioned at a right angle to the fiber axis by a polishing machine (trade name: ML-110N, manufactured by Marto Co., Ltd.). Next, plasma etching was performed for 5 minutes under the condition of an output of 50 W using a plasma etching apparatus (manufactured by JEOL Datum Co., Ltd., trade name: JP-170). Au was sputtered to a thickness of about 10 nm by a product name: JFC-1100). An image obtained by observing the obtained test piece with a scanning electron microscope (manufactured by JEOL Ltd., trade name: JSM-6060A) at 1000 times was obtained. About the obtained image, the outer shape of the cross section of the single fiber was traced by image measurement software (manufactured by Nippon Roper Co., Ltd., trade name: Image-Pro PLUS). (Maximum ferret diameter) D1 and short diameter (minimum ferret diameter) D2 were measured. Using these values, the flatness coefficient and the rough surface coefficient were calculated by the following equations. These values were measured for 50 or more single fibers, and the average value was obtained for each.
偏平係数＝Ｄ１／Ｄ２
粗面係数＝（Ｌ／π）／（４×Ａ／π）1/2
また、得られた炭素繊維束の評価方法は、以下の通りである。
Flatness factor = D1 / D2
Roughness coefficient = (L / π) / (4 × A / π) 1/2
Moreover, the evaluation method of the obtained carbon fiber bundle is as follows.
（樹脂含浸性）
約２０ｃｍに切り取った炭素繊維束をグリシジルエーテル中に約３ｃｍ浸し、１５分間放置した。グリシジルエーテル中から炭素繊維束を取り出した後３分間放置し、下から３．５ｃｍのところで切り落とし、残った炭素繊維束の長さ、質量を測定した。炭素繊維束の目付けから吸い上げたグリシジルエーテルの質量割合を算出し、樹脂含浸性の指標とした。吸い上げたグリシジルエーテルの質量割合が３％以上を「○」、３％未満を「×」とした。
(Resin impregnation)
A carbon fiber bundle cut to about 20 cm was immersed in glycidyl ether for about 3 cm and left for 15 minutes. The carbon fiber bundle was taken out from the glycidyl ether and allowed to stand for 3 minutes, cut off from the bottom at 3.5 cm, and the length and mass of the remaining carbon fiber bundle were measured. The mass ratio of glycidyl ether sucked up from the basis weight of the carbon fiber bundle was calculated and used as an index for resin impregnation. When the mass ratio of the glycidyl ether sucked up was 3% or more, “◯” was given, and when it was less than 3%, “X” was given.
（開繊性）
炭素繊維束を０．０６ｇ／単繊維の張力下、走行速度１ｍ／分で金属ロール上を走行させた際のトウ幅を測定し、開繊性の指標とした。トウ幅が２ｍｍ以上を「○」、２ｍｍ未満を「×」とした。
(Opening property)
The tow width when the carbon fiber bundle was run on a metal roll at a running speed of 1 m / min under a tension of 0.06 g / single fiber was used as an index of the spreadability. A tow width of 2 mm or more was designated as “◯”, and a width less than 2 mm was designated as “x”.
［実施例１］
アクリロニトリル、アクリルアミドおよびメタクリル酸を、過硫酸アンモニウム−亜硫酸水素アンモニウムおよび硫酸鉄の存在下、水系懸濁重合により共重合し、アクリロニトリル単位／アクリルアミド単位／メタクリル酸単位＝９６／３／１（質量比）からなるアクリロニトリル系重合体を得た。このアクリロニトリル系重合体をジメチルアセトアミドに溶解し、濃度２１質量％の紡糸原液を調製した。
[Example 1]
Acrylonitrile, acrylamide and methacrylic acid were copolymerized by aqueous suspension polymerization in the presence of ammonium persulfate-ammonium hydrogen sulfite and iron sulfate, and acrylonitrile unit / acrylamide unit / methacrylic acid unit = 96/3/1 (mass ratio) An acrylonitrile-based polymer was obtained. This acrylonitrile-based polymer was dissolved in dimethylacetamide to prepare a spinning dope with a concentration of 21% by mass.
この紡糸原液を孔数３０００、孔径７５μｍの紡糸口金を通して、濃度６５質量％、温度３５℃のジメチルアセトアミド水溶液からなる第１凝固浴中に吐出させて凝固糸にし、この凝固糸を、第１凝固浴中から紡糸原液の吐出線速度の０．６倍の引取り速度で引き取った。引き続き、この凝固糸を、第１凝固浴と同条件の濃度６５質量％、温度３５℃のジメチルアセトアミド水溶液からなる第２凝固浴に導き、第２凝固浴中にて１．８０倍に延伸した。 This spinning dope is passed through a spinneret having a pore number of 3000 and a pore diameter of 75 μm and discharged into a first coagulation bath made of a dimethylacetamide aqueous solution having a concentration of 65% by mass and a temperature of 35 ° C. to obtain a coagulated yarn. It was taken out from the bath at a take-up speed 0.6 times the discharge linear speed of the spinning dope. Subsequently, the coagulated yarn was led to a second coagulation bath made of a dimethylacetamide aqueous solution having a concentration of 65% by mass and a temperature of 35 ° C. under the same conditions as the first coagulation bath, and stretched 1.80 times in the second coagulation bath. .
次いで、得られた繊維束を水洗すると同時に３．５倍の湿熱延伸を行い、これに１．１質量％に調製したアミノシリコーン系油剤を添油した。得られた繊維束を熱ロールを用いて乾燥し、スチーム延伸機にて２．１倍に延伸した。その後、タッチロールにて繊維束の水分率を調整し、この繊維束に繊維当たり８質量％の水分を含有させた。次いで、この繊維束を、圧力２００ｋＰａのエアーによって交絡処理し、ワインダーで巻き取ることにより、単繊維繊度１．２ｄｔｅｘのアクリロニトリル系前駆体繊維束を得た。紡糸時に毛羽が発生することなく、紡糸安定性は良好であった。得られた前駆体繊維束の集束性を確認するとともに、断面形状パラメーターを測定した。また、湿熱延伸後の繊維束を採取して、その膨潤度を測定した。 Next, the obtained fiber bundle was washed with water and stretched by 3.5 times of wet heat, and an aminosilicone-based oil prepared to 1.1% by mass was added thereto. The obtained fiber bundle was dried using a hot roll and stretched 2.1 times with a steam stretching machine. Thereafter, the moisture content of the fiber bundle was adjusted with a touch roll, and the fiber bundle contained 8% by mass of water per fiber. Next, the fiber bundle was entangled with air having a pressure of 200 kPa and wound with a winder to obtain an acrylonitrile-based precursor fiber bundle with a single fiber fineness of 1.2 dtex. The spinning stability was good without fluffing during spinning. While confirming the convergence of the obtained precursor fiber bundle, the cross-sectional shape parameter was measured. Moreover, the fiber bundle after wet heat drawing was extract | collected, and the swelling degree was measured.
さらに、前駆体繊維束を空気中２３０〜２６０℃の熱風循環式耐炎化炉にて５０分間処理して耐炎化繊維束とし、次いで耐炎繊維束を窒素雰囲気中下で最高温度７８０℃にて１．５分間処理し、さらに同雰囲気下で最高温度が１３００℃の高温熱処理炉にて約１．５分処理した。その後、重炭酸水素アンモニウム水溶液中で０．４Ａｍｉｎ／ｍで電解処理を施して、炭素繊維束を得た。なお、焼成工程通過性に問題はなかった。得られた炭素繊維束の断面形状パラメーターを測定するとともに、樹脂含浸性および開繊性を評価した。 Further, the precursor fiber bundle was treated in a hot air circulation type flameproofing furnace at 230 to 260 ° C in air for 50 minutes to form a flameproofed fiber bundle, and then the flameproof fiber bundle was 1 at a maximum temperature of 780 ° C in a nitrogen atmosphere. For 5 minutes, and further in the same atmosphere for about 1.5 minutes in a high-temperature heat treatment furnace having a maximum temperature of 1300 ° C. Thereafter, electrolytic treatment was performed at 0.4 Amin / m in an aqueous solution of ammonium bicarbonate to obtain a carbon fiber bundle. In addition, there was no problem in the baking process passability. While measuring the cross-sectional shape parameter of the obtained carbon fiber bundle, the resin impregnation property and the fiber opening property were evaluated.
［比較例１］
アクリロニトリル系重合体の組成を、アクリロニトリル単位／アクリル酸メチル単位／メタクリル酸単位＝９６／３／１（質量比）とした以外は、実施例１と同様にして単繊維繊度１．２ｄｔｅｘの前駆体繊維束を得た。紡糸時に毛羽が発生することなく、紡糸安定性は良好であった。得られた前駆体繊維束の集束性を確認するとともに、断面形状パラメーターを測定した。また、湿熱延伸後の繊維束を採取して、その膨潤度を測定した。
[Comparative Example 1]
Precursor having a single fiber fineness of 1.2 dtex in the same manner as in Example 1 except that the composition of the acrylonitrile polymer is acrylonitrile unit / methyl acrylate unit / methacrylic acid unit = 96/3/1 (mass ratio). A fiber bundle was obtained. The spinning stability was good without fluffing during spinning. While confirming the convergence of the obtained precursor fiber bundle, the cross-sectional shape parameter was measured. Moreover, the fiber bundle after wet heat drawing was extract | collected, and the swelling degree was measured.
さらに、この前駆体繊維束を実施例１と同様に焼成した。焼成工程において繊維束を構成する単繊維がばらけて隣接する繊維束が若干絡まるなど、焼成工程通過性に劣っていた。得られた炭素繊維束の断面形状パラメーターを測定するとともに、樹脂含浸性および開繊性を評価した。 Further, this precursor fiber bundle was fired in the same manner as in Example 1. In the firing process, the single fibers constituting the fiber bundle were scattered and the adjacent fiber bundles were slightly entangled. While measuring the cross-sectional shape parameter of the obtained carbon fiber bundle, the resin impregnation property and the fiber opening property were evaluated.
［比較例２］
第２凝固浴槽をバイパスして、空中延伸（冷延伸）にて１．８倍延伸を施した以外は、実施例１と同様にして単繊維繊度１．２ｄｔｅｘの前駆体繊維束の製造を試みた。しかし、紡糸安定性が悪く、前駆体繊維束を得ることができなかった。なお、湿熱延伸後の繊維束を採取して、その膨潤度を測定した。
[Comparative Example 2]
An attempt was made to produce a precursor fiber bundle having a single fiber fineness of 1.2 dtex in the same manner as in Example 1 except that the second coagulation bath was bypassed and 1.8-fold drawing was performed by air drawing (cold drawing). It was. However, the spinning stability was poor and a precursor fiber bundle could not be obtained. In addition, the fiber bundle after wet heat drawing was extract | collected, and the swelling degree was measured.
［比較例３］
水洗後の湿熱延伸倍率を２．３倍、スチーム延伸機倍率を３．２倍に変更した以外は、実施例１と同様にして単繊維繊度１．２ｄｔｅｘの前駆体繊維束を得た。紡糸時に毛羽が発生することなく、紡糸安定性は良好であった。得られた前駆体繊維束の集束性を確認するとともに、断面形状パラメーターを測定した。また、湿熱延伸後の繊維束を採取して、その膨潤度を測定した。
[Comparative Example 3]
A precursor fiber bundle having a single fiber fineness of 1.2 dtex was obtained in the same manner as in Example 1 except that the wet heat draw ratio after washing with water was changed to 2.3 times and the steam drawing machine ratio was changed to 3.2 times. The spinning stability was good without fluffing during spinning. While confirming the convergence of the obtained precursor fiber bundle, the cross-sectional shape parameter was measured. Moreover, the fiber bundle after wet heat drawing was extract | collected, and the swelling degree was measured.
さらに、この前駆体繊維束を実施例１と同様に焼成した。焼成工程において繊維束を構成する単繊維がばらけて隣接する繊維束が若干絡まるなど、焼成工程通過性に劣っていた。得られた炭素繊維束の断面形状パラメーターを測定するとともに、樹脂含浸性および開繊性を評価した。 Further, this precursor fiber bundle was fired in the same manner as in Example 1. In the firing process, the single fibers constituting the fiber bundle were scattered and the adjacent fiber bundles were slightly entangled. While measuring the cross-sectional shape parameter of the obtained carbon fiber bundle, the resin impregnation property and the fiber opening property were evaluated.
［比較例４］
第２凝固浴中での浴中延伸倍率が２．２倍に変更した以外は、実施例１と同様にして単繊維繊度１．２ｄｔｅｘの前駆体繊維束を得た。紡糸時に若干の毛羽が発生し、紡糸安定性に劣っていた。得られた前駆体繊維束の集束性を確認するとともに、断面形状パラメーターを測定した。また、湿熱延伸後の繊維束を採取して、その膨潤度を測定した。
[Comparative Example 4]
A precursor fiber bundle having a single fiber fineness of 1.2 dtex was obtained in the same manner as in Example 1 except that the draw ratio in the second coagulation bath was changed to 2.2 times. Some fluff was generated during spinning, and the spinning stability was poor. While confirming the convergence of the obtained precursor fiber bundle, the cross-sectional shape parameter was measured. Moreover, the fiber bundle after wet heat drawing was extract | collected, and the swelling degree was measured.
さらに、この前駆体繊維束を実施例１と同様に焼成した。焼成工程において毛羽が隣接する繊維に絡まるなど、焼成工程通過性に劣っていた。得られた炭素繊維束の断面形状パラメーターを測定するとともに、樹脂含浸性および開繊性を評価した。 Further, this precursor fiber bundle was fired in the same manner as in Example 1. In the baking process, the fluff was entangled with the adjacent fibers, and the passing through the baking process was poor. While measuring the cross-sectional shape parameter of the obtained carbon fiber bundle, the resin impregnation property and the fiber opening property were evaluated.
［比較例５］
第１凝固浴および第２凝固浴におけるジメチルアセトアミド水溶液の濃度を５０質量％、温度を３０℃に変更した以外は、実施例１と同様にして前駆体繊維束を得た。紡糸時に毛羽が発生し、紡糸安定性に劣っていた。得られた前駆体繊維束の集束性を確認するとともに、断面形状パラメーターを測定した。また、湿熱延伸後の繊維束を採取して、その膨潤度を測定した。
[Comparative Example 5]
A precursor fiber bundle was obtained in the same manner as in Example 1 except that the concentration of the dimethylacetamide aqueous solution in the first coagulation bath and the second coagulation bath was changed to 50% by mass and the temperature was changed to 30 ° C. Fluff was generated during spinning, and the spinning stability was poor. While confirming the convergence of the obtained precursor fiber bundle, the cross-sectional shape parameter was measured. Moreover, the fiber bundle after wet heat drawing was extract | collected, and the swelling degree was measured.
さらに、この前駆体繊維束を実施例１と同様に焼成した。焼成工程において毛羽が隣接する繊維に絡まるなど、焼成工程通過性に劣っていた。得られた炭素繊維束の断面形状パラメーターを測定するとともに、樹脂含浸性および開繊性を評価した。 Further, this precursor fiber bundle was fired in the same manner as in Example 1. In the baking process, the fluff was entangled with the adjacent fibers, and the passing through the baking process was poor. While measuring the cross-sectional shape parameter of the obtained carbon fiber bundle, the resin impregnation property and the fiber opening property were evaluated.
以上の結果を、表１にまとめて示す。 The above results are summarized in Table 1.
Claims (4)
９５質量％以上のアクリロニトリル単位と、０．５〜４．０質量％のアクリルアミド単位とを含有するアクリロニトリル系重合体の有機溶剤溶液からなる紡糸溶液を、有機溶剤濃度５５〜６８質量％、温度３３〜４０℃の有機溶剤水溶液が投入された第１凝固浴中に吐出して凝固糸とするとともに、前記紡糸原液の吐出線速度の０．６以下の速度で、前記第１凝固浴中から前記凝固糸を引き取る工程と、
前記引き取られた凝固糸に対して、前記第１凝固浴と同じ条件の有機溶剤水溶液が投入された第２凝固浴中にて１．５〜２．０倍の延伸を施す工程と、
前記第２凝固浴中で延伸された繊維束に対して、３．０倍以上の湿熱延伸を施す工程と、
前記湿熱延伸された繊維束に対して、シリコーン系油剤の添油処理を行う工程と、
前記添油処理された繊維束を乾燥した後、その繊維束に対して、１．５〜２．５倍のスチーム延伸を施す工程と
を有する炭素繊維前駆体繊維束の製造方法。 It is a manufacturing method of the carbon fiber precursor fiber bundle according to claim 1,
A spinning solution comprising an organic solvent solution of an acrylonitrile-based polymer containing 95% by mass or more of acrylonitrile units and 0.5 to 4.0% by mass of acrylamide units was prepared by using an organic solvent concentration of 55 to 68% by mass and a temperature of 33. It is discharged into a first coagulation bath charged with an organic solvent aqueous solution of ˜40 ° C. to obtain a coagulated yarn, and from the first coagulation bath at a speed of 0.6 or less of the discharge linear speed of the spinning dope. A step of taking the coagulated yarn;
A step of stretching 1.5 to 2.0 times in the second coagulation bath in which the organic solvent aqueous solution having the same condition as the first coagulation bath is charged with respect to the taken-up coagulated yarn;
A step of subjecting the fiber bundle drawn in the second coagulation bath to wet heat drawing of 3.0 times or more;
A process of adding a silicone-based oil to the wet-heat-stretched fiber bundle;
A method of producing a carbon fiber precursor fiber bundle, comprising: drying the oil-treated fiber bundle, and subjecting the fiber bundle to steam stretching of 1.5 to 2.5 times.
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| JP5741815B2 (en) * | 2011-03-09 | 2015-07-01 | 三菱レイヨン株式会社 | Carbon fiber precursor acrylic fiber bundle and carbon fiber bundle |
| JP5948791B2 (en) * | 2011-10-25 | 2016-07-06 | 三菱レイヨン株式会社 | Method for preparing cross-sectional sample of wet porous fiber |
| JP6477546B2 (en) * | 2016-03-09 | 2019-03-06 | 東レ株式会社 | Method for producing carbon fiber precursor fiber bundle, method for producing carbon fiber bundle, and carbon fiber bundle |
| KR102385506B1 (en) * | 2017-02-16 | 2022-04-11 | 미쯔비시 케미컬 주식회사 | Carbon fiber precursor acrylic fiber, carbon fiber, and manufacturing method for same |
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| JP3892212B2 (en) * | 2000-07-03 | 2007-03-14 | 三菱レイヨン株式会社 | Carbon fiber precursor fiber bundle |
| JP2002294518A (en) * | 2001-03-30 | 2002-10-09 | Mitsubishi Rayon Co Ltd | Carbon fiber precursor acrylonitrile-based yarn and method for producing the same |
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