JP5072668B2 - Precursor fiber, and method for producing precursor fiber, flame-resistant fiber and carbon fiber - Google Patents
Precursor fiber, and method for producing precursor fiber, flame-resistant fiber and carbon fiber Download PDFInfo
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本発明は、高強度、高伸度の炭素繊維製造用の前駆体繊維、並びに、前駆体繊維、耐炎化繊維及び炭素繊維の製造方法に関する。 The present invention relates to a precursor fiber for producing a high-strength, high-stretch carbon fiber, and a precursor fiber, a flame-resistant fiber, and a method for producing a carbon fiber.
従来、炭素繊維製造用の前駆体繊維を原料として用い、これに耐炎化処理を施して耐炎化繊維を得ること、更にこの耐炎化繊維に炭素化処理を施して高性能炭素繊維を得ることは広く知られている。また、この方法は工業的にも実施されている。 Conventionally, a precursor fiber for producing carbon fiber is used as a raw material, and flameproofing treatment is performed on this to obtain a flameproofing fiber. Further, carbonization treatment is applied to this flameproofing fiber to obtain a high-performance carbon fiber. Widely known. This method is also practiced industrially.
一般に、炭素繊維製造用の前駆体繊維としてはアクリル系繊維が用いられる。このアクリル系繊維から炭素繊維を製造する場合、アクリル系繊維を２００〜３００℃の酸化性雰囲気下で延伸又は収縮を行いながら耐炎化処理を行った後、３００℃以上、場合により１０００℃以上の不活性ガス雰囲気中で炭素化して炭素繊維を製造する。 In general, acrylic fibers are used as precursor fibers for producing carbon fibers. When producing carbon fiber from this acrylic fiber, after performing flameproofing treatment while stretching or shrinking the acrylic fiber in an oxidizing atmosphere of 200 to 300 ° C., it is 300 ° C. or higher, and in some cases 1000 ° C. or higher. Carbon fiber is produced by carbonization in an inert gas atmosphere.
炭素繊維製造の効率を高めるためには、安定して耐炎化処理をすることが必要とされている。この耐炎化処理の安定化に関する技術については多くの提案がなされている(例えば、特許文献１〜６参照)。 In order to increase the efficiency of carbon fiber production, it is necessary to stably perform flameproofing treatment. Many proposals have been made regarding the technology relating to stabilization of the flameproofing treatment (see, for example, Patent Documents 1 to 6).
特許文献１には、耐炎化工程に先立ち別個の前処理工程を設けて繊維密度が所定の範囲になるまで前処理して次行程の耐炎化処理を安定化させることが開示されている。 Patent Document 1 discloses that a separate pretreatment step is provided prior to the flameproofing step, and pretreatment is performed until the fiber density reaches a predetermined range to stabilize the flameproofing treatment in the next step.
特許文献２、３には、耐炎化処理に先立ち２００℃以上の加熱体表面に繰返し接触させて前処理し、次行程の耐炎化処理を安定化させることが開示されている。 Patent Documents 2 and 3 disclose that the surface of a heating body at 200 ° C. or higher is repeatedly contacted and pretreated prior to the flameproofing treatment to stabilize the flameproofing treatment in the next step.
特許文献４〜６には、耐炎化処理に先立ち酸化性雰囲気の乾燥機中２００℃以下で熱処理することが開示されている。 Patent Documents 4 to 6 disclose that heat treatment is performed at 200 ° C. or less in a dryer in an oxidizing atmosphere prior to the flameproofing treatment.
しかし、特許文献１〜６の何れの従来技術においても、得られる炭素繊維の強度、伸度は不充分である。
本発明者は、上記問題を解決するため検討を重ねた。その結果、従来の方法で得られる前駆体繊維は水蒸気を用いたガス吸着法で評価される水蒸気の吸着量が多く、水を吸い易い構造であることを見出した。これに対し、アクリル系共重合体を紡糸して得られるアクリル系繊維を、水洗、乾燥、スチーム延伸処理し、次いで、空気中に浮かんだ状態で、所定温度で熱処理(予備熱処理)して得られる繊維は、水蒸気吸着量が極端に減少すると共に、上記繊維を前駆体繊維として耐炎化処理、炭素化処理して得られる炭素繊維は、高強度、高伸度であることを本発明者は見出し、本発明を完成するに到った。 The inventor has repeatedly studied to solve the above problem. As a result, it has been found that the precursor fiber obtained by the conventional method has a structure in which the amount of water vapor adsorbed evaluated by the gas adsorption method using water vapor is large and water is easily absorbed. In contrast, acrylic fibers obtained by spinning an acrylic copolymer are washed with water, dried and steam-stretched, and then heat treated at a predetermined temperature (preliminary heat treatment) in a state of floating in the air. The present inventors have found that the carbon fibers obtained by subjecting the above-mentioned fibers to a flame resistance treatment and carbonization treatment using the above fibers as precursor fibers have high strength and high elongation while the amount of water vapor absorbed is extremely reduced. The headline and the present invention have been completed.
よって、本発明の目的とするところは、上記問題を解決し、高強度、高伸度の炭素繊維製造用の前駆体繊維及び耐炎化繊維の製造方法、並びに、炭素繊維の製造方法を提供することにある。 Therefore, the object of the present invention is to solve the above problems and provide a precursor fiber and a flame-resistant fiber production method for producing high-strength and high-strength carbon fiber, and a carbon fiber production method. There is.
上記目的を達成する本発明は、以下に記載するものである。 The present invention for achieving the above object is described below.
〔１〕 水蒸気を用いたガス吸着量測定装置によって測定される湿度９０％での水蒸気吸着量が３〜９ｃｍ3／ｇの繊維である炭素繊維製造用前駆体繊維。 [1] A precursor fiber for carbon fiber production, which is a fiber having a water vapor adsorption amount of 3 to 9 cm 3 / g at a humidity of 90% as measured by a gas adsorption amount measuring device using water vapor.
〔２〕 アクリロニトリルを９０質量％以上含有する単量体を重合した共重合体を紡糸して得られるアクリル系繊維を、水洗、乾燥、スチーム延伸処理し、次いで、空気中に浮かんだ状態で１７０〜２５０℃、延伸比０．９０〜１．１０で熱処理することを特徴とする、水蒸気を用いたガス吸着量測定装置によって測定される湿度９０％での水蒸気吸着量が３〜９ｃｍ3／ｇの繊維である炭素繊維製造用前駆体繊維の製造方法。 [2] Acrylic fiber obtained by spinning a copolymer obtained by polymerizing a monomer containing 90% by mass or more of acrylonitrile is washed with water, dried, steam-stretched, and then floated in air. The water vapor adsorption amount at a humidity of 90% measured by a gas adsorption amount measuring apparatus using water vapor is 3-9 cm 3 / g measured by a gas adsorption amount measuring apparatus using water vapor, characterized by heat treatment at ˜250 ° C. and a stretch ratio of 0.90-1.10 Of a precursor fiber for producing carbon fiber, which is a fiber of the above.
〔３〕 アクリロニトリルを９０質量％以上含有する単量体を重合した共重合体を紡糸して得られるアクリル系繊維を、水洗、乾燥、スチーム延伸処理し、次いで、空気中に浮かんだ状態で１７０〜２５０℃、延伸比０．９０〜１．１０で熱処理して、水蒸気を用いたガス吸着量測定装置によって測定される湿度９０％での水蒸気吸着量が３〜９ｃｍ3／ｇの炭素繊維製造用前駆体繊維を得、前記前駆体繊維を、空気中、ローラー又は支持ガイドに接触させつつ、２００〜３００℃、延伸比０．８０〜１．２０で熱処理することを特徴とする耐炎化繊維の製造方法。 [3] Acrylic fiber obtained by spinning a copolymer obtained by polymerizing a monomer containing 90% by mass or more of acrylonitrile is washed with water, dried and steam-stretched, and then in a state of being floated in the air. Production of carbon fiber having a water vapor adsorption amount of 3 to 9 cm 3 / g at 90% humidity measured by a gas adsorption amount measuring apparatus using water vapor by heat treatment at ˜250 ° C. and a stretch ratio of 0.90 to 1.10. A precursor fiber for heat treatment, and heat-treating the precursor fiber at 200 to 300 ° C. and a draw ratio of 0.80 to 1.20 while contacting the precursor fiber with a roller or a support guide in the air. Manufacturing method.
〔４〕 アクリロニトリルを９０質量％以上含有する単量体を重合した共重合体を紡糸して得られるアクリル系繊維を、水洗、乾燥、スチーム延伸処理し、次いで、空気中に浮かんだ状態で１７０〜２５０℃、延伸比０．９０〜１．１０で熱処理して、水蒸気を用いたガス吸着量測定装置によって測定される湿度９０％での水蒸気吸着量が３〜９ｃｍ3／ｇの炭素繊維製造用前駆体繊維を得、前記前駆体繊維を、空気中、ローラー又は支持ガイドに接触させつつ、２００〜３００℃、延伸比０．８０〜１．２０で熱処理して耐炎化繊維を得、前記耐炎化繊維を不活性ガス雰囲気中、温度８００〜２５００℃で炭素化処理することを特徴とする炭素繊維の製造方法。 [4] Acrylic fiber obtained by spinning a copolymer obtained by polymerizing a monomer containing 90% by mass or more of acrylonitrile was washed with water, dried and steam-stretched, and then in a state of floating in air. Production of carbon fiber having a water vapor adsorption amount of 3 to 9 cm 3 / g at 90% humidity measured by a gas adsorption amount measuring apparatus using water vapor by heat treatment at ˜250 ° C. and a stretch ratio of 0.90 to 1.10. The precursor fiber for use is obtained, and the precursor fiber is heat treated at 200 to 300 ° C. and a draw ratio of 0.80 to 1.20 in contact with a roller or a support guide in the air to obtain a flame resistant fiber. A method for producing carbon fiber, comprising subjecting the flame-resistant fiber to carbonization treatment at a temperature of 800 to 2500 ° C. in an inert gas atmosphere.
本発明の製造方法によれば、紡糸後、空気中で他の物に接触することなく、所定温度で熱処理して水蒸気吸着量を用いて表現される繊維の細孔を所定の範囲に低減させているので、高強度、高伸度の炭素繊維を容易に得ることができる。 According to the production method of the present invention, after spinning, the pores of the fiber expressed using the water vapor adsorption amount are reduced to a predetermined range by heat treatment at a predetermined temperature without contacting other objects in the air. Therefore, a carbon fiber having high strength and high elongation can be easily obtained.
以下、本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail.
本発明の炭素繊維製造用前駆体繊維は、アクリロニトリルを９０質量％以上含有する単量体を重合した共重合体を紡糸して得られた繊維を、水洗、乾燥、スチーム延伸処理し、次いで、油剤等の添加物を添加すること無く空気中に浮かんだ状態で、他の支持体等に接触することなく１７０〜２５０℃、延伸比０．９０〜１．１０で熱処理して得られる、水蒸気を用いたガス吸着量測定装置によって測定される湿度９０％での水蒸気吸着量が３〜９ｃｍ3／ｇの繊維である。 The precursor fiber for carbon fiber production of the present invention is obtained by spinning a fiber obtained by spinning a copolymer obtained by polymerizing a monomer containing 90% by mass or more of acrylonitrile, followed by washing with water, drying, and steam drawing. Water vapor obtained by heat treatment at 170 to 250 ° C. and a stretch ratio of 0.90 to 1.10 without contacting other supports and the like in a state of floating in the air without adding an additive such as an oil agent. It is a fiber having a water vapor adsorption amount of 3 to 9 cm 3 / g at a humidity of 90% as measured by a gas adsorption amount measuring device using
この前駆体繊維を、空気中、ローラー又は支持ガイドに接触させつつ、２００〜３００℃、延伸比０．８０〜１．２０で熱処理することにより本発明の炭素繊維製造用耐炎化繊維は製造される。 The flame-resistant fiber for producing carbon fiber of the present invention is produced by heat-treating the precursor fiber at 200 to 300 ° C. and a draw ratio of 0.80 to 1.20 while contacting the precursor fiber with a roller or a support guide in the air. The
この耐炎化繊維を、不活性ガス雰囲気中、温度８００〜２５００℃で炭素化処理することにより本発明の炭素繊維は製造される。 The carbon fiber of the present invention is produced by carbonizing the flame-resistant fiber at a temperature of 800 to 2500 ° C. in an inert gas atmosphere.
更に具体的に述べると、本発明の炭素繊維製造用前駆体繊維、耐炎化繊維、炭素繊維は、例えば、以下の方法により製造することができる。 More specifically, the precursor fiber for producing a carbon fiber, the flame-resistant fiber, and the carbon fiber of the present invention can be produced, for example, by the following method.
＜紡糸原液＞
本例の炭素繊維ストランドの製造方法に用いる前駆体繊維の紡糸原液は、炭素繊維製造用の紡糸原液であれば従来公知のものが何ら制限なく使用できる。そのなかでもアクリル系炭素繊維製造用の紡糸原液が好ましい。具体的には、アクリロニトリルを９０質量％以上、好ましくは９４質量％以上含有する単量体を重合した共重合体からなる紡糸原液が挙げられる。アクリロニトリルと共重合する単量体としては、イタコン酸、アクリル酸メチル、アクリル酸エチル、アクリル酸等の公知の単量体が挙げられる。
<Spinning stock solution>
The precursor fiber spinning solution used in the carbon fiber strand production method of this example can be any known one as long as it is a spinning solution for producing carbon fibers. Among these, a spinning dope for producing acrylic carbon fibers is preferable. Specifically, a stock solution for spinning composed of a copolymer obtained by polymerizing a monomer containing 90% by mass or more, preferably 94% by mass or more of acrylonitrile is exemplified. Examples of the monomer copolymerized with acrylonitrile include known monomers such as itaconic acid, methyl acrylate, ethyl acrylate, and acrylic acid.
＜紡糸＞
上記紡糸原液を、１つの紡糸口金に好ましくは１０００以上の孔、より好ましくは２００００以上の孔を有する紡糸口金から紡糸原液を紡出し、紡糸後の炭素繊維製造用原料繊維とする。この紡糸に際しては、低温に冷却した凝固液(紡糸する際の溶媒−水混合液)を入れた凝固浴中に紡出する方法、湿式紡糸方法又は乾湿式紡糸方法等を用いることができるが、直接凝固液に紡出する湿式紡糸方法が好ましい。乾湿式紡糸方法は、空気中にまず吐出させた後、３〜５ｍｍ程度の空間を有して凝固浴に投入し凝固させる方法である。最終的に得られた炭素繊維が表面に襞を形成し、樹脂との接着性が期待できるので、湿式紡糸方法がより好ましい。
<Spinning>
The spinning stock solution is spun from a spinning base having preferably 1,000 or more holes, more preferably 20000 or more holes in one spinneret, and used as a raw fiber for producing carbon fiber after spinning. In this spinning, a method of spinning in a coagulation bath containing a coagulating liquid cooled to a low temperature (a solvent-water mixture at the time of spinning), a wet spinning method, a dry-wet spinning method, or the like can be used. A wet spinning method of spinning directly into a coagulation liquid is preferred. The dry-wet spinning method is a method in which after first discharging into the air, it has a space of about 3 to 5 mm and is put into a coagulation bath and coagulated. Since the finally obtained carbon fiber forms wrinkles on the surface and adhesion with the resin can be expected, the wet spinning method is more preferable.
凝固した後は、水洗・乾燥・スチーム延伸処理し、延伸処理後の炭素繊維製造用原料繊維とする。 After coagulation, washing with water, drying and steam drawing are performed to obtain a raw material fiber for carbon fiber production after drawing.
乾燥工程においては、温度勾配をかけた幾層にも連なる部屋を有する熱風乾燥機で乾燥することが好ましい。乾燥温度については、７０〜１５０℃で適宜調節して行うことが好ましく、８０〜１４０℃で適宜調節して行うことが更に好ましい。乾燥時間については、１〜１０分間が好ましい。 In the drying step, it is preferable to dry with a hot air drier having a number of layers connected to a temperature gradient. About drying temperature, it is preferable to adjust suitably at 70-150 degreeC, and it is still more preferable to adjust suitably at 80-140 degreeC. The drying time is preferably 1 to 10 minutes.
スチーム延伸条件において飽和スチーム圧力は、０．６〜０．８ＭＰａ(絶対圧)とすることが好ましい。延伸倍率は、水洗・乾燥・スチーム延伸処理を通してのトータル延伸倍率で１０〜１５倍とすることが好ましい。スチーム延伸処理後の繊度は０．５〜０．７ｄｔｅｘとすることが好ましい。 In the steam stretching conditions, the saturated steam pressure is preferably 0.6 to 0.8 MPa (absolute pressure). The stretching ratio is preferably 10 to 15 times as the total stretching ratio through washing, drying and steam stretching. The fineness after the steam stretching treatment is preferably 0.5 to 0.7 dtex.
＜予備熱処理＞
スチーム延伸処理後の繊維は、引き続き加熱空気中１７０〜２５０℃、延伸比０．９０〜１．１０で１００〜３００秒熱処理(予備熱処理)される。この予備熱処理により得られる繊維は、水蒸気を用いたガス吸着量測定装置で後述する測定方法によって測定される湿度９０％での水蒸気吸着量が３〜９ｃｍ3／ｇの炭素繊維製造用前駆体繊維に調製される。
<Preliminary heat treatment>
The fiber after the steam drawing treatment is subsequently heat treated (preliminary heat treatment) for 100 to 300 seconds in a heated air at 170 to 250 ° C. and a draw ratio of 0.90 to 1.10. The fiber obtained by this preliminary heat treatment is a precursor fiber for producing carbon fiber having a water vapor adsorption amount of 3 to 9 cm 3 / g at a humidity of 90% measured by a measurement method described later with a gas adsorption amount measurement device using water vapor. To be prepared.
この処理は空気中に浮かんだ状態で行われ、他の物(ローラー、支持ガイド等)に一切接触しないことが重要である。ローラー等に接触すると、所望の性能の炭素繊維製造用前駆体繊維が得られない。 It is important that this treatment is performed in a state of floating in the air and does not come into contact with other objects (rollers, support guides, etc.) at all. When it comes into contact with a roller or the like, a precursor fiber for producing carbon fiber having a desired performance cannot be obtained.
このことは、次のように考えられる。即ち、１５０℃以下の熱処理しか受けていないスチーム延伸処理後の繊維は構造が不安定であり、予備熱処理では均一な加熱を必要とする。しかし、予備熱処理中に繊維がローラー等に接触すると、ストランドの接触面と非接触面との間で温度斑が生じたり、接触の前後で張力変化が生じたりするため、所望の性能の炭素繊維製造用前駆体繊維が得られない。 This is considered as follows. That is, the structure of the fiber after the steam drawing treatment that has been subjected to only heat treatment at 150 ° C. or lower is unstable, and the preliminary heat treatment requires uniform heating. However, if the fiber comes into contact with a roller or the like during preliminary heat treatment, temperature fluctuations occur between the contact surface and the non-contact surface of the strand, or tension changes before and after the contact. A precursor fiber for production cannot be obtained.
予備熱処理温度が１７０℃未満の場合、若しくは延伸比が１．１０を超える場合は、前駆体繊維の水蒸気吸着量が過多になり、前駆体繊維を耐炎化処理、炭素化処理して得られる炭素繊維の強度、伸度が低下するので好ましくない。予備熱処理温度が２５０℃を超える場合は、炭素化処理して得られる炭素繊維の強度、伸度が低下するので好ましくない。なお、延伸比が０．９未満の場合は予備熱処理工程及びその後の熱処理工程が不安定となるのため好ましくない。 When the preliminary heat treatment temperature is less than 170 ° C., or when the draw ratio exceeds 1.10, the amount of water vapor adsorbed on the precursor fiber becomes excessive, and carbon obtained by subjecting the precursor fiber to flame resistance treatment and carbonization treatment. This is not preferable because the strength and elongation of the fiber are lowered. When the preliminary heat treatment temperature exceeds 250 ° C., the strength and elongation of the carbon fiber obtained by the carbonization treatment are lowered, which is not preferable. A stretch ratio of less than 0.9 is not preferable because the preliminary heat treatment step and the subsequent heat treatment step become unstable.
予備熱処理して得られる前駆体繊維の密度は１．２ｇ／ｃｍ3以下とすることが好ましい。 The density of the precursor fiber obtained by the preliminary heat treatment is preferably 1.2 g / cm 3 or less.
＜耐炎化処理＞
前駆体繊維は、引き続き加熱空気中、ローラー又は支持ガイドに接触させつつ、２００〜３００℃で耐炎化処理される。この耐炎化処理により、前駆体繊維がアクリル系繊維の場合、アクリル系繊維の環化反応を生じさせ、酸素結合量を増加させて不融化、難燃化させてアクリル系耐炎化繊維(ＯＰＦ)を得る。
<Flame resistance treatment>
The precursor fiber is subjected to a flame resistance treatment at 200 to 300 ° C. while being in contact with a roller or a support guide in heated air. By this flameproofing treatment, when the precursor fiber is an acrylic fiber, a cyclization reaction of the acrylic fiber is caused, and the amount of oxygen bonds is increased to make it infusible and flame retardant to make the acrylic flameproof fiber (OPF). Get.
耐炎化処理においては、前駆体繊維を耐炎化炉内に長時間滞留させる必要がある。また、生産効率から炉内の前駆体繊維の走行速度は上げる必要がある。そのため、前駆体繊維は一旦耐炎化炉の外部に出た後、折り返して耐炎化炉に繰り返し通過させる方法が採られる。それでも、炉内を走行する前駆体繊維は長いものとなり、炉内で撓んでしまう。すると、前駆体繊維は下方を走行する繊維や炉底等に接触し易くなり、糸切れや汚染などの運転トラブルを生ずる。このことから、前駆体繊維は炉内で撓まないようにローラー又は支持ガイドに接触させつつ耐炎化処理することになる。しかし、上述したように、予備熱処理していない従来の前駆体繊維は構造が不安定であるため、ローラー又は支持ガイドに接触すると、所望の性能の炭素繊維製造用耐炎化繊維が得られない。 In the flameproofing treatment, it is necessary to retain the precursor fiber in the flameproofing furnace for a long time. In addition, it is necessary to increase the traveling speed of the precursor fibers in the furnace from the production efficiency. Therefore, after the precursor fiber once goes out of the flameproofing furnace, it is folded and repeatedly passed through the flameproofing furnace. Even so, the precursor fibers traveling in the furnace become long and bend in the furnace. As a result, the precursor fibers are likely to come into contact with the fibers running underneath, the bottom of the furnace, and the like, causing operational troubles such as yarn breakage and contamination. For this reason, the precursor fiber is subjected to a flame resistance treatment while being in contact with a roller or a support guide so as not to bend in the furnace. However, as described above, since the structure of the conventional precursor fiber that has not been subjected to the preliminary heat treatment is unstable, when it comes into contact with the roller or the support guide, the flame-resistant fiber for producing carbon fiber having the desired performance cannot be obtained.
これに対し、本発明の前駆体繊維は、上記予備熱処理を施しているので、予備熱処理していない従来の前駆体繊維ほどは均一な加熱を必要としない。そのため、耐炎化炉内を、ローラー又は支持ガイドに接触させつつ、耐炎化処理しても、所望の性能の炭素繊維製造用耐炎化繊維を得ることができる。耐炎化炉内におけるローラー又は支持ガイドの間隔は１〜１０ｍが好ましく、２〜４ｍがより好ましい。 On the other hand, since the precursor fiber of the present invention is subjected to the preliminary heat treatment, it does not require as uniform heating as the conventional precursor fiber that has not been subjected to the preliminary heat treatment. Therefore, even if the inside of the flameproofing furnace is brought into contact with the roller or the support guide and flameproofing is performed, the flameproofing fiber for producing carbon fibers having a desired performance can be obtained. The distance between the rollers or the support guides in the flameproofing furnace is preferably 1 to 10 m, and more preferably 2 to 4 m.
この耐炎化処理は、一般的に、延伸倍率０．８５〜１．３０の範囲で延伸されることが好ましい。この耐炎化処理により、密度１．３〜１．５ｇ／ｃｍ3の耐炎化繊維が得られる。耐炎化時の張力は上記延伸倍率の範囲を超えない限り特に限定されない。 In general, the flameproofing treatment is preferably performed in a range of a draw ratio of 0.85 to 1.30. By this flameproofing treatment, a flameproof fiber having a density of 1.3 to 1.5 g / cm 3 is obtained. The tension at the time of flame resistance is not particularly limited as long as it does not exceed the range of the draw ratio.
なお、耐炎化工程の工程安定化のため、前述の前駆体繊維に公知のプロセスオイルを付与することも有効である。 In addition, it is also effective to apply a known process oil to the above-mentioned precursor fiber in order to stabilize the flameproofing process.
＜第一炭素化処理＞
上記耐炎化繊維は、従来の公知の方法を採用して炭素化することができる。例えば、窒素雰囲気下３００〜８００℃の焼成炉(第一炭素化炉)で徐々に温度勾配をかけ、耐炎化繊維の張力を制御して緊張下で１段目の炭素化(第一炭素化)をする。
<First carbonization treatment>
The flame-resistant fiber can be carbonized by employing a conventionally known method. For example, a temperature gradient is gradually applied in a firing furnace (first carbonization furnace) at 300 to 800 ° C. in a nitrogen atmosphere, and the tension of the flame-resistant fiber is controlled to perform first-stage carbonization (first carbonization). )do.
＜第二炭素化処理＞
より炭素化を進め且つグラファイト化(炭素の高結晶化)を進める為に、窒素等の不活性ガス雰囲気下で昇温し、焼成炉(第二炭素化炉)で徐々に温度勾配をかけ、第一炭素化繊維の張力を制御して弛緩条件で焼成する。
<Second carbonization treatment>
To further promote carbonization and graphitization (high crystallization of carbon), raise the temperature in an inert gas atmosphere such as nitrogen, gradually apply a temperature gradient in the firing furnace (second carbonization furnace), The first carbonized fiber is fired under relaxed conditions by controlling the tension.
焼成温度については、第二炭素化炉で温度勾配をかけていき、最高温度領域で、好ましくは８００℃から２５００℃、より好ましくは１２００℃から２１００℃がよい。 About a calcination temperature, a temperature gradient is applied in a 2nd carbonization furnace, Preferably it is 800 to 2500 degreeC in a maximum temperature range, More preferably, 1200 to 2100 degreeC is good.
炉内の高温部での滞留時間が長くなると、グラファイト化が進み過ぎ、脆性化した炭素繊維が得られることになるので好ましくない。 If the residence time in the high-temperature part in the furnace becomes long, graphitization proceeds too much, and brittle carbon fibers are obtained, which is not preferable.
＜表面酸化処理＞
上記第二炭素化処理繊維は、引き続き表面酸化処理を施す。表面酸化処理には気相、液相処理も用いることができるが、工程管理の簡便さと生産性を高める点から、液相処理が好ましい。液相処理のうちでも、液の安全性・安定性の面から、電解液を用いる電解処理が好ましい。電解酸化処理に用いられる電解液としては、硫酸、硝酸、塩酸等の無機酸や、水酸化ナトリウム、水酸化カリウムなどの無機水酸化物、硫酸アンモニウム、炭酸ナトリウム、炭酸水素ナトリウム等の無機塩類などが挙げられる。
<Surface oxidation treatment>
The second carbonized fiber is subsequently subjected to surface oxidation treatment. A gas phase or liquid phase treatment can also be used for the surface oxidation treatment, but the liquid phase treatment is preferable from the viewpoint of easy process control and productivity. Among the liquid phase treatments, electrolytic treatment using an electrolytic solution is preferable from the viewpoint of liquid safety and stability. Examples of the electrolytic solution used for the electrolytic oxidation treatment include inorganic acids such as sulfuric acid, nitric acid, and hydrochloric acid, inorganic hydroxides such as sodium hydroxide and potassium hydroxide, and inorganic salts such as ammonium sulfate, sodium carbonate, and sodium bicarbonate. Can be mentioned.
＜サイジング処理＞
上記表面酸化処理後の繊維は、必要に応じ、引き続いてサイジング処理を施す。サイジング方法は、従来の公知の方法で行うことができ、サイジング剤は、用途に即して適宜組成を変更して使用し、均一付着させた後に、乾燥することが好ましい。
<Sizing process>
The fiber after the surface oxidation treatment is subsequently subjected to sizing treatment as necessary. The sizing method can be carried out by a conventionally known method, and the sizing agent is preferably used after changing its composition as appropriate according to the application, and after uniformly adhering.
以上の製造方法により得られる炭素繊維は、５９２０ＭＰａ以上の高強度、１．９８％以上の高伸度である。 The carbon fiber obtained by the above production method has a high strength of 5920 MPa or more and a high elongation of 1.98% or more.
以下、本発明を実施例及び比較例により更に具体的に説明する。また、各実施例及び比較例における処理条件、並びに、前駆体繊維、耐炎化繊維及び炭素繊維の物性についての評価方法は以下の方法により実施した。 Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. Moreover, the processing method in each Example and a comparative example, and the evaluation method about the physical property of a precursor fiber, a flame-resistant fiber, and a carbon fiber were implemented with the following method.
＜耐炎化繊維の密度＞
アルキメデス法により測定した。試料繊維はアセトン中にて脱気処理し測定した。
<Density of flameproof fiber>
Measured by Archimedes method. The sample fiber was degassed in acetone and measured.
＜前駆体繊維の水蒸気吸着量＞
前駆体繊維の水蒸気吸着量は、前駆体繊維を長さ１５ｃｍ程度(０．３ｇ程度)に切り出したものを、ユアサアイオニクス(株)社製全自動ガス吸着量装置「AUTOSORB-1」を使用し、下記条件
吸着ガス：Ｈ2Ｏ
死容積：Ｈe
吸着温度：２９３Ｋ
測定範囲：相対圧(Ｐ／Ｐｏ) ＝ ０〜１．０
Ｐ：測定圧、Ｐｏ：Ｈ2Ｏの飽和蒸気圧
により測定した。湿度９０％での水蒸気吸着量の値は、相対圧(Ｐ／Ｐｏ)が０．９となる箇所で得た値である。
<Water vapor adsorption amount of precursor fiber>
The amount of water vapor adsorbed by the precursor fiber is obtained by cutting the precursor fiber to a length of about 15 cm (about 0.3 g) and using the fully automated gas adsorption device “AUTOSORB-1” manufactured by Yuasa Ionics Co., Ltd. The following conditions Adsorption gas: H 2 O
Dead volume: He
Adsorption temperature: 293K
Measuring range: relative pressure (P / Po) = 0-1.0
P: Measurement pressure and Po: H 2 O saturated vapor pressure. The value of the water vapor adsorption amount at a humidity of 90% is a value obtained at a location where the relative pressure (P / Po) is 0.9.
＜炭素繊維の強度、弾性率、伸度＞
ＪＩＳ Ｒ ７６０１に規定された方法により炭素繊維(ＣＦ)の強度、弾性率、伸度を測定した。
<Strength, elastic modulus, and elongation of carbon fiber>
The strength, elastic modulus, and elongation of the carbon fiber (CF) were measured by the method defined in JIS R7601.
実施例１
アクリロニトリル９５質量％／アクリル酸メチル４質量％／イタコン酸１質量％よりなる共重合体紡糸原液を、１つの紡糸口金に２４０００の孔を有する紡糸口金(２４０００フィラメント用の紡糸口金)を通して、塩化亜鉛水溶液中に吐出して凝固させ、凝固糸を得た。
Example 1
A copolymer spinning stock solution consisting of 95% by mass of acrylonitrile / 4% by mass of methyl acrylate / 1% by mass of itaconic acid was passed through a spinneret (spinneret for 24000 filaments) having 24,000 holes in one spinneret, and then zinc chloride It was discharged into an aqueous solution and solidified to obtain a solidified yarn.
この凝固糸を、水洗・乾燥・スチーム延伸処理し、スチーム延伸処理後の繊維を得た。水洗・乾燥・スチーム延伸処理を通してのトータル延伸倍率は１４倍であり、得られたスチーム延伸処理後の繊維の繊度は０．７２ｄｔｅｘであった。 The coagulated yarn was washed with water, dried and subjected to steam drawing treatment to obtain a fiber after the steam drawing treatment. The total draw ratio through the washing, drying and steam drawing treatment was 14 times, and the fineness of the fiber after the obtained steam drawing treatment was 0.72 dtex.
この繊維を、表１に示す処理条件に設定した乾燥機(予備熱処理装置)に滞留時間３分で空気中に浮かんだ状態で通過させて予備熱処理し、表１に示す水蒸気吸着量で、密度１．１８ｇ／ｃｍ3の前駆体繊維を得た。 This fiber was passed through a dryer (preliminary heat treatment apparatus) set to the treatment conditions shown in Table 1 in a state of floating in the air with a residence time of 3 minutes, and preliminarily heat treated. A precursor fiber of 1.18 g / cm 3 was obtained.
この前駆体繊維を、熱風循環式耐炎化炉の最高温度域を２５０℃に設定した加熱空気中、炉内のガイドで支持しつつ通過させ、延伸倍率を０．９〜１．１の範囲内で制御して耐炎化処理し、密度１．３６ｇ／ｃｍ3の耐炎化繊維を得た。耐炎化炉内の支持ガイドの間隔は３ｍであった。 This precursor fiber is allowed to pass while being supported by a guide in the furnace in heated air in which the maximum temperature range of the hot air circulation type flameproofing furnace is set to 250 ° C., and the draw ratio is in the range of 0.9 to 1.1. And flameproofing treatment was performed to obtain a flameproof fiber having a density of 1.36 g / cm 3 . The distance between the support guides in the flameproofing furnace was 3 m.
この耐炎化繊維を、第一炭素化炉の不活性雰囲気中３００〜８００℃の温度域を通過させて第一炭素化処理を施した。 This flame-resistant fiber was subjected to a first carbonization treatment by passing through a temperature range of 300 to 800 ° C. in an inert atmosphere of the first carbonization furnace.
この第一炭素化処理繊維を、第二炭素化炉の不活性雰囲気中８００〜２０００℃の温度域を通過させて第二炭素化処理を施した。 The first carbonized fiber was subjected to a second carbonization treatment by passing through a temperature range of 800 to 2000 ° C. in an inert atmosphere of a second carbonization furnace.
次いで、この第二炭素化処理繊維を、硫酸アンモニウム水溶液を電解液として用い、炭素繊維１ｇ当り３０クーロンの電気量で表面処理を施した。 Next, this second carbonized fiber was subjected to a surface treatment using an aqueous ammonium sulfate solution as an electrolytic solution at an electric quantity of 30 coulomb per 1 g of carbon fiber.
引き続き公知の方法で、サイジング剤を施し、乾燥して表１に示す強度、弾性率、伸度の炭素繊維を得た。 Subsequently, a sizing agent was applied by a known method and dried to obtain carbon fibers having the strength, elastic modulus and elongation shown in Table 1.
実施例２
実施例１で得られた前駆体繊維について、シリコーン系油剤をプロセスオイル(ＰＯ)として用い、繊維質量に対し０．１質量％付与した。ＰＯ付与後の前駆体繊維は、実施例１と同様に、耐炎化処理、第一炭素化処理、第二炭素化処理、表面酸化処理、サイジング処理を行い、耐炎化繊維、表１に示す強度、弾性率、伸度の炭素繊維を得た。
Example 2
About the precursor fiber obtained in Example 1, 0.1 mass% was provided with respect to the fiber mass using the silicone type oil agent as process oil (PO). The precursor fiber after the PO application was subjected to flameproofing treatment, first carbonization treatment, second carbonization treatment, surface oxidation treatment, and sizing treatment in the same manner as in Example 1. The carbon fiber of elastic modulus and elongation was obtained.
実施例３〜５、比較例１〜４
実施例１と同様に凝固、水洗、乾燥、スチーム延伸して得られた繊維を、表１に示す処理条件で予備熱処理し、表１に示す水蒸気吸着量、密度の前駆体繊維を得た。得られた各前駆体繊維について、シリコーン系油剤をプロセスオイル(ＰＯ)として用い、繊維質量に対し０．１質量％付与した。ＰＯ付与後の各前駆体繊維は、実施例１と同様に、耐炎化処理、第一炭素化処理、第二炭素化処理、表面酸化処理、サイジング処理を行い、耐炎化繊維、表１に示す強度、弾性率、伸度の炭素繊維を得た。
Examples 3-5, Comparative Examples 1-4
Fibers obtained by coagulation, water washing, drying and steam drawing in the same manner as in Example 1 were preheated under the treatment conditions shown in Table 1 to obtain precursor fibers having water vapor adsorption amounts and densities shown in Table 1. About each obtained precursor fiber, the silicone type oil agent was used as process oil (PO), and 0.1 mass% was provided with respect to the fiber mass. Each precursor fiber after PO application is subjected to flame resistance treatment, first carbonization treatment, second carbonization treatment, surface oxidation treatment, and sizing treatment in the same manner as in Example 1, and is shown in Table 1. A carbon fiber having strength, elastic modulus and elongation was obtained.
予備熱処理工程での延伸比が０．７０と低い比較例３の場合、乾燥機(予備熱処理装置)内において前駆体繊維が撓んでしまい、その通過性が著しく悪化した。また、予備熱処理工程での延伸比が１．２０と高い比較例４の場合、水蒸気吸着量が本発明の構成範囲から外れてしまう結果となった。 In the case of Comparative Example 3 where the draw ratio in the preliminary heat treatment step was as low as 0.70, the precursor fibers were bent in the dryer (preliminary heat treatment apparatus), and the passability was remarkably deteriorated. Moreover, in the case of the comparative example 4 with a high stretch ratio in the preliminary heat treatment step of 1.20, the water vapor adsorption amount deviated from the configuration range of the present invention.
Claims (2)
Acrylic fiber obtained by spinning a copolymer obtained by polymerizing a monomer containing 90% by mass or more of acrylonitrile is washed with water, dried, and subjected to steam drawing treatment, and then floats in the air without adding an additive. In this state, heat treatment is performed at 170 to 240 ° C. and a stretch ratio of 0.95 to 1.10, and the water vapor adsorption amount at a temperature of 293 K and a humidity of 90% is 7.9 as measured by a gas adsorption amount measuring apparatus using water vapor. After obtaining a precursor fiber for carbon fiber production of ˜9 cm 3 / g and applying process oil to the precursor fiber, it is brought into contact with a roller or a support guide in the air, at 200 to 300 ° C., and a draw ratio of 0.80. A method for producing carbon fiber, characterized in that a flame-resistant fiber is obtained by heat treatment at ˜1.20, and the flame-resistant fiber is carbonized at 800 to 2500 ° C. in an inert gas atmosphere.
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