JP2008184721A - Method for producing carbon fiber - Google Patents
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本発明は、炭素繊維を使用した複合材料の品質を安定させ、かつ複合材料の成型コストを低減させることが可能な炭素繊維の製造方法に関する。 The present invention relates to a carbon fiber manufacturing method capable of stabilizing the quality of a composite material using carbon fibers and reducing the molding cost of the composite material.
炭素繊維は、優れた機械的強度を有するため、航空宇宙素材、スポーツ、レジャー用素材、圧力容器などの工業用素材として極めて有用であり、需要が拡大している。また、今後はさらに幅広い分野で利用されることが期待されている。
一般に、炭素繊維は、ポリアクリロニトリルなどの前駆体フィラメントを束ねた前駆体繊維束を、酸化性雰囲気で満たした耐炎化炉で耐炎化処理した後、得られた耐炎化繊維束を窒素などの不活性雰囲気で満たした炭素化炉で炭素化処理することによって得られる。
炭素繊維は、通常、そのままでは利用されず、樹脂との組み合わせによる複合材料として成型され、様々な用途に利用される。炭素繊維の需要拡大において、複合材料の品質安定化や、複合材料の成型コスト低減は、重要な課題である。
Since carbon fibers have excellent mechanical strength, they are extremely useful as industrial materials such as aerospace materials, sports materials, leisure materials, and pressure vessels, and the demand for carbon fibers is expanding. In the future, it is expected to be used in a wider range of fields.
In general, carbon fiber is obtained by subjecting a precursor fiber bundle obtained by bundling precursor filaments such as polyacrylonitrile to a flame resistance furnace filled with an oxidizing atmosphere, and then converting the obtained flame resistant fiber bundle to a non-nitrogen or the like. It can be obtained by carbonizing in a carbonization furnace filled with an active atmosphere.
Carbon fiber is not usually used as it is, but is molded as a composite material in combination with a resin and used for various purposes. In expanding the demand for carbon fiber, stabilizing the quality of composite materials and reducing the molding cost of composite materials are important issues.
炭素繊維を用いた複合材料を成型する方法としては、複数本の炭素繊維束を並列に引き揃えてシート状にし、薄い樹脂フィルムを含浸させた中間材料（プリプレグ）として成型する方法や、樹脂を含浸した炭素繊維束をライナー材（成型物の骨格となる基材）に巻き付けてから、樹脂を硬化させることで成型物を得るフィラメントワインディング成型法が挙げられる。その他、炭素繊維束を樹脂に含浸させた後、加熱した金型に連続的に通して成型物を得るプルトルージョン成型法が挙げられる。なお、フィラメントワインディング成型法は、高圧ガスタンクなどの圧力容器の製造に好適に用いられる。 As a method of molding a composite material using carbon fibers, a method of molding a plurality of carbon fiber bundles in parallel to form a sheet and molding as an intermediate material (prepreg) impregnated with a thin resin film, or a resin There is a filament winding molding method in which the impregnated carbon fiber bundle is wound around a liner material (a base material serving as a skeleton of the molded product) and then the resin is cured to obtain a molded product. In addition, there is a pultrusion molding method in which a resin is impregnated with a carbon fiber bundle and then continuously passed through a heated mold to obtain a molded product. The filament winding molding method is preferably used for manufacturing a pressure vessel such as a high-pressure gas tank.
これらの成型方法に用いられる炭素繊維としては、より多くの炭素フィラメントを並列に引き揃えた炭素繊維束、すなわち、幅広の炭素繊維束であることが好ましい。幅広の炭素繊維束であれば、炭素繊維と樹脂による複合材料の成型において、ボビンから炭素繊維を引き出すためのクリールの数が少なくて済むため、成型コストを低減でき、経済的である。 The carbon fiber used in these molding methods is preferably a carbon fiber bundle in which more carbon filaments are aligned in parallel, that is, a wide carbon fiber bundle. If the carbon fiber bundle is wide, the molding cost can be reduced because the number of creels for drawing the carbon fiber from the bobbin can be reduced in molding the composite material of carbon fiber and resin, which is economical.
幅広の炭素繊維束を得る方法としては、炭素繊維の元となる前駆体繊維の段階において、予め幅広の前駆体繊維束を形成することが考えられる。例えば、紡糸ノズルの穴間の距離を狭くし、より多くのノズルを設けることで、得られる前駆体フィラメント数を増やし、幅広の前駆体繊維束を形成する方法がある。しかしながら、紡糸ノズルの穴間の距離を狭くすると、前駆体フィラメント同士が融着しやすくなり、紡糸性が不安定になる問題があった。
前駆体繊維の段階で幅広の前駆体繊維束を得る他の方法としては、紡糸ノズルを大きくすることで、前駆体フィラメント自体を太くし、これにより前駆体繊維束を幅広にすることが考えられる。しかしながら、前駆体フィラメントが太くなると、作業性が著しく損なわれてしまう。また、紡糸設備も大型になるため、設備投資に多くの費用を必要とする問題があった。
As a method for obtaining a wide carbon fiber bundle, it is conceivable to form a wide precursor fiber bundle in advance at the stage of the precursor fiber that is the source of the carbon fiber. For example, there is a method of forming a wide precursor fiber bundle by narrowing the distance between the holes of the spinning nozzle and providing more nozzles to increase the number of precursor filaments obtained. However, when the distance between the holes of the spinning nozzle is narrowed, the precursor filaments are easily fused to each other, and there is a problem that the spinnability becomes unstable.
As another method for obtaining a wide precursor fiber bundle at the precursor fiber stage, it is conceivable to enlarge the precursor filament itself by enlarging the spinning nozzle, thereby widening the precursor fiber bundle. . However, when the precursor filament is thick, workability is significantly impaired. In addition, since the spinning equipment is large, there is a problem that a large amount of cost is required for capital investment.
幅広の炭素繊維束を得るための別の方法としては、複数の小繊維束を並列に引き揃えて組み合わせる方法、すなわち、小繊維束同士を合糸して幅広の繊維束を形成する方法が挙げられる。例えば、特許文献１では、炭素化処理前または炭素化処理中に小繊維束を合糸した後、取り扱い性を向上させるためのサイジング剤を付与して巻き取ることによって、幅広の炭素繊維束を得る方法が提案されている。
しかしながら、特許文献１の方法では、合糸の程度が充分ではないため、複合材料の成型過程において、合糸した繊維束が合糸前の繊維束に分かれてしまうことがある。このように繊維配列が乱れた状態で成型すると、各繊維束に加わる張力が不均一になるため、複合材料の物性が低下してしまう。 However, in the method of Patent Document 1, since the degree of the combined yarn is not sufficient, the combined fiber bundle may be divided into the fiber bundle before the combined yarn in the molding process of the composite material. When molding is performed in such a state where the fiber arrangement is disturbed, the tension applied to each fiber bundle becomes non-uniform, and the physical properties of the composite material are deteriorated.
本発明はこのような状況に鑑みてなされたものであり、安定した品質の複合材料を得ることができ、かつ複合材料の成型コストを低減させることが可能な炭素繊維の製造方法を目的とする。 This invention is made | formed in view of such a condition, and it aims at the manufacturing method of the carbon fiber which can obtain the composite material of the stable quality and can reduce the shaping | molding cost of a composite material. .
[１]前駆体繊維を耐炎化炉で耐炎化処理する耐炎化工程と、耐炎化工程後の耐炎化繊維を炭素化炉で炭素化処理する炭素化工程とを有する炭素繊維の製造方法において、耐炎化工中に、前記前駆体繊維からなる小繊維束にかける張力が１０４〜２４３ｍｇ／ｄｔｅｘの範囲内で、かつ前記小繊維束の密度が１．３１〜１．３７ｍｇ／ｃｍ３の範囲内で、複数の前記小繊維束を溝ロールに導入して合糸することを特徴とする炭素繊維の製造方法。
[２]合糸した耐炎化繊維の総繊度が７０００ｄｔｅｘ以上であることを特徴とする[１]に記載の炭素繊維の製造方法。
[1] In a method for producing carbon fiber, comprising: a flameproofing step of flameproofing a precursor fiber in a flameproofing furnace; and a carbonization step of carbonizing the flameproofed fiber after the flameproofing step in a carbonization furnace, During the flameproofing process, the tension applied to the fibril bundle made of the precursor fiber is within the range of 104 to 243 mg / dtex, and the density of the fibril bundle is within the range of 1.31 to 1.37 mg / cm 3. A method for producing carbon fiber, wherein a plurality of the small fiber bundles are introduced into a groove roll and combined.
[2] The method for producing a carbon fiber according to [1], wherein the combined fineness of the flameproof fiber is 7000 dtex or more.
本発明によれば、安定した品質の複合材料を得ることができ、かつ複合材料の成型コストを低減させることが可能な炭素繊維の製造方法を提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the carbon fiber which can obtain the composite material of the stable quality and can reduce the shaping | molding cost of a composite material can be provided.
本発明の製造方法によって得られる炭素繊維は、前駆体繊維を耐炎化炉で耐炎化処理する耐炎化工程と、耐炎化工程後の耐炎化繊維を炭素化炉で炭素化処理する炭素化工程とを経て製造される。
前駆体繊維としては、例えば、ポリアクリロニトリル系、ピッチ系、レーヨン系が挙げられるが、コストと性能のバランスから、好ましくはポリアクリロニトリル系が用いられる。以下に、ポリアクリロニトリル系炭素繊維の製造方法を例に挙げて、本発明の炭素繊維の製造方法について説明する。
The carbon fiber obtained by the production method of the present invention includes a flameproofing process in which the precursor fiber is flameproofed in a flameproofing furnace, and a carbonization process in which the flameproofed fiber after the flameproofing process is carbonized in a carbonization furnace; It is manufactured through.
Examples of the precursor fiber include polyacrylonitrile-based, pitch-based, and rayon-based fibers. From the balance of cost and performance, polyacrylonitrile-based is preferably used. Below, the manufacturing method of the polyacrylonitrile-type carbon fiber is mentioned as an example, and the manufacturing method of the carbon fiber of this invention is demonstrated.
ポリアクリロニトリル系の炭素繊維を製造するには、まず、アクリロニトリル系単量体を含有する単量体組成物を重合することでポリアクリロニトリル共重合体を得て、これを溶剤に希釈してポリアクリロニトリル紡糸原液とする。
重合の方法としては特に限定されないが、例えば、溶液重合、懸濁重合などが挙げられる。ポリアクリロニトリル紡糸原液に用いられる溶剤としては特に限定されないが、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などの有機溶剤や、塩化亜鉛、チオシアン酸ナトリウムなどの無機化合物の水溶液が挙げられる。
In order to produce a polyacrylonitrile-based carbon fiber, first, a monomer composition containing an acrylonitrile-based monomer is polymerized to obtain a polyacrylonitrile copolymer, which is diluted with a solvent to obtain a polyacrylonitrile. Use a spinning dope.
Although it does not specifically limit as a polymerization method, For example, solution polymerization, suspension polymerization, etc. are mentioned. The solvent used for the polyacrylonitrile spinning dope is not particularly limited, and examples thereof include organic solvents such as dimethylacetamide, dimethylsulfoxide, and dimethylformamide, and aqueous solutions of inorganic compounds such as zinc chloride and sodium thiocyanate.
ポリアクリロニトリル紡糸原液は、次いで、糸状に紡糸される。紡糸の方法としては、ノズルより凝固浴中に吐出させる湿式法、或いはノズルから紡糸原液を空中に吐出した後に凝固浴中へ入れる半湿式法のいずれか方法も用いることができる。
紡糸された繊維フィラメントの集合物には、次いで、延伸処理、洗浄処理が行われ、前駆体繊維の小束、すなわち、前駆体小繊維束となる。
The polyacrylonitrile spinning dope is then spun into a yarn. As a spinning method, any of a wet method in which a spinning solution is discharged from a nozzle into a coagulation bath, or a semi-wet method in which a spinning solution is discharged from the nozzle into the air and then put into the coagulation bath can be used.
Next, the aggregate of the spun fiber filaments is subjected to a drawing treatment and a washing treatment to form a precursor fiber small bundle, that is, a precursor small fiber bundle.
得られた前駆体小繊維束には、次いで、耐熱性を付与する油剤処理が行われる。油剤処理は、耐炎化処理中の前駆体繊維束において、前駆体繊維束を形成する前駆体フィラメントが互いに融着するのを防ぐために行われる。油剤処理を行わないと、前記融着が生じ、焼成が不均一になる、或いは炭素化工程での毛羽や糸切れといった障害が起こる。油剤処理に用いられる油剤としては、例えば、アミノシリコン系油剤、各種カチオン系活性剤、ポリオキシアルキレンエーテルなどが挙げられるが、中でもアミノシリコン系油剤が好ましく用いられる。この油剤処理後、前駆体繊維束には、公知の方法によって乾燥緻密化処理、後延伸処理が行われる。 The resulting precursor fibril bundle is then subjected to an oil treatment that imparts heat resistance. The oil agent treatment is performed to prevent the precursor filaments forming the precursor fiber bundle from fusing together in the precursor fiber bundle during the flameproofing treatment. If the oil agent treatment is not performed, the above-described fusion occurs and firing becomes uneven, or problems such as fluff and yarn breakage in the carbonization process occur. Examples of the oil agent used for the oil agent treatment include aminosilicon-based oil agents, various cationic activators, and polyoxyalkylene ethers. Of these, aminosilicon-based oil agents are preferably used. After this oil agent treatment, the precursor fiber bundle is subjected to dry densification treatment and post-stretching treatment by a known method.
これらの処理を経た前駆体繊維束は、次いで、耐炎化炉に投入されて耐炎化処理される。耐炎化炉内には、２００〜３００℃の酸化性雰囲気が循環しており、前駆体繊維束は該酸化性雰囲気中を走行する間に耐炎化処理される。なお、耐炎化炉内を循環する酸化性雰囲気の流れは、走行する被処理繊維に対して平行方向でも、垂直方向でもよく、特に限定されない。
前駆体繊維束の耐炎化処理に要する時間は、炭素繊維の生産性及び性能を高める観点から３０分以上が好ましく、４５分以上がより好ましい。耐炎化処理に要する時間が３０分未満では、耐炎化反応が不充分になり、斑を生じやすく、後に行われる炭素化工程で毛羽、束切れを生じ、結果的に生産性が低下することがある。耐炎化処理に要する時間の上限は、１００分が好ましく、８０分がより好ましい。耐炎化処理に要する時間が１００分以上では、炭素繊維の強度が低下することがある。
The precursor fiber bundle that has undergone these treatments is then placed in a flameproofing furnace and subjected to a flameproofing treatment. An oxidizing atmosphere of 200 to 300 ° C. circulates in the flameproofing furnace, and the precursor fiber bundle is flameproofed while traveling in the oxidizing atmosphere. In addition, the flow of the oxidizing atmosphere circulating in the flameproofing furnace may be parallel or perpendicular to the traveling fiber to be processed, and is not particularly limited.
The time required for the flame resistance treatment of the precursor fiber bundle is preferably 30 minutes or more, and more preferably 45 minutes or more from the viewpoint of improving the productivity and performance of the carbon fibers. If the time required for the flameproofing treatment is less than 30 minutes, the flameproofing reaction becomes insufficient, and spots are likely to occur, and fluff and bundle breakage occur in the subsequent carbonization process, resulting in a decrease in productivity. is there. The upper limit of the time required for the flameproofing treatment is preferably 100 minutes, and more preferably 80 minutes. If the time required for the flameproofing treatment is 100 minutes or more, the strength of the carbon fiber may be lowered.
本発明における小繊維束同士の合糸は、耐炎化工程中に複数本の小繊維束を溝ロールに導入することにより行われる。耐炎化工程中に合糸を行うことにより、小繊維束同士がフィラメント単位で絡み合い、再び分離しにくい幅広の耐炎化繊維束を得ることができる。
耐炎化炉内を走行する複数の小繊維束は、走行経路の途中に配置された溝ロールによって互いに引き寄せられ、溝ロールの溝に沿って水平方向に引き揃えられることで合糸され、幅広の耐炎化繊維束となる。
なお、配置される溝ロールの数は単数でもよく複数でもよく、特に限定されない。また、溝ロールのピッチ及び溝形状は、合糸する繊維のボリュームにより適宜最適な溝ロールを選定する。特に溝形状によっては、溝底と溝上部の繊維束の張力斑を生じたり、溝側面への擦れによって毛羽が発生する場合があるので、溝形状は選定が必要である。
In the present invention, the joining of the small fiber bundles is performed by introducing a plurality of small fiber bundles into the groove roll during the flameproofing step. By performing the yarn combination during the flameproofing step, a wide flameproof fiber bundle that is entangled with each other in filament units and difficult to separate again can be obtained.
A plurality of small fiber bundles traveling in the flameproofing furnace are attracted to each other by a grooved roll arranged in the middle of the traveling path, and are aligned by being horizontally aligned along the groove of the grooved roll, so that the wide yarn It becomes a flameproof fiber bundle.
In addition, the number of the groove roll arrange | positioned may be single and plural, and is not specifically limited. In addition, as for the pitch and groove shape of the groove roll, an optimum groove roll is appropriately selected according to the volume of fibers to be combined. In particular, depending on the groove shape, there is a case where the fiber bundle at the groove bottom and the upper part of the groove has uneven tension, or fluff is generated by rubbing against the groove side surface, so the groove shape needs to be selected.
本発明における小繊維束同士の合糸は、小繊維束にかける張力が１０４〜２４３ｍｇ／ｄｔｅｘの範囲内で、かつ小繊維束の密度が１．３１〜１．３７ｍｇ／ｃｍ３の範囲内で行われる。
小繊維束にかける張力として、より好ましくは１１７〜１７３ｍｇ／ｄｔｅｘである。小繊維束の張力が１０４ｍｇ／ｄｔｅｘ未満では、張力が低いため、合糸における小繊維束同士の圧着が弱くなる。小繊維束同士の圧着力が弱い炭素繊維束を複合材料の成型過程に用いると、炭素繊維束が成型過程の途中で合糸前の小繊維束に分かれてしまうことが多い。また、張力が２４３ｍｇ／ｄｔｅｘを超えると、得られる耐炎化繊維束に毛羽が生じてしまう。
小繊維束の密度として、より好ましくは１．３２〜１．３５ｍｇ／ｃｍ３以下である。繊維束の密度が１．３１／ｃｍ３未満では、それだけ溝ロールでの圧着回数を多くしなければならず、効率が悪くなる。溝ロールでの圧着回数が多くなると、繊維束に過剰な張力が加わり、耐炎化構造が十分に発達していない耐炎化初段の繊維束にとってダメージとなり、毛羽が発生してしまう危険性がある。繊維束の密度が１．３７ｍｇ／ｃｍ３を超えると、耐炎化の進み過ぎにより酸素が過剰に導入されるため、後の炭素化工程で毛羽が発生しやすくなる。
The combined yarn of the small fiber bundles in the present invention has a tension applied to the small fiber bundles within a range of 104 to 243 mg / dtex and a density of the small fiber bundles within a range of 1.31 to 1.37 mg / cm 3. Done.
The tension applied to the fibril bundle is more preferably 117 to 173 mg / dtex. When the tension of the fibril bundle is less than 104 mg / dtex, the tension is low, and the crimping of the fibril bundles in the combined yarn becomes weak. When a carbon fiber bundle having a weak crimping force between small fiber bundles is used in the molding process of the composite material, the carbon fiber bundle is often divided into small fiber bundles before being combined during the molding process. Moreover, when tension | tensile_strength exceeds 243 mg / dtex, a fluff will arise in the flame-resistant fiber bundle obtained.
The density of the fibril bundle is more preferably 1.32 to 1.35 mg / cm 3 or less. If the density of the fiber bundle is less than 1.31 / cm 3 , the number of times of crimping with the groove roll must be increased accordingly, and the efficiency becomes worse. When the number of times of crimping with the groove roll is increased, excessive tension is applied to the fiber bundle, which may cause damage to the first flame-resistant fiber bundle in which the flame-resistant structure is not sufficiently developed, and may cause fluff. When the density of the fiber bundle exceeds 1.37 mg / cm 3 , oxygen is excessively introduced due to excessive progress of flame resistance, and fluff is likely to occur in the subsequent carbonization step.
合糸した耐炎化繊維束の繊度（繊維１００００ｍ当たりの質量）は、総繊度７０００ｄｔｅｘ以上であることが好ましい。より好ましくは総繊度１００００ｄｔｅｘ以上である。総繊度７０００ｄｔｅｘ未満では、合糸しても複合材料の成型コストがあまり変わらず、コストメリットが小さい。総繊度の上限は特に限定されないが、５００００ｄｔｅｘ以下が好ましい。総繊度が５００００ｄｔｅｘ以上であると、合糸した耐炎化繊維束が耐炎化工程で蓄熱して、過剰な発熱反応を起こし、繊維が切れやすくなる。また、溝ロールに導入された耐炎化繊維束の、溝底に位置する炭素フィラメントと上面に位置する炭素フィラメントとの張力斑が大きくなり、毛羽が発生しやすくなる。 The fineness (mass per 10,000 m of fibers) of the combined flameproof fiber bundle is preferably 7000 dtex or more. More preferably, the total fineness is 10,000 dtex or more. When the total fineness is less than 7000 dtex, the molding cost of the composite material does not change much even if the yarns are combined, and the cost merit is small. The upper limit of the total fineness is not particularly limited, but is preferably 50000 dtex or less. When the total fineness is 50000 dtex or more, the combined flameproof fiber bundle accumulates heat in the flameproofing process, causes an excessive exothermic reaction, and the fibers are easily cut. Further, in the flame-resistant fiber bundle introduced into the groove roll, the tension unevenness between the carbon filament located at the groove bottom and the carbon filament located at the upper surface is increased, and fluff is likely to occur.
このようにして得られた耐炎化繊維束は、次いで、炭素化工程を経て炭素繊維となる。すなわち、窒素などの不活性雰囲気が満たされた炭素化炉に投入され、炭素化処理される。炭素化工程には、公知の方法を用いることができる。炭素化温度や伸張率は、目的の弾性率に応じて適宜変更される。 The flame-resistant fiber bundle thus obtained is then converted into carbon fiber through a carbonization step. That is, it is put into a carbonization furnace filled with an inert atmosphere such as nitrogen and carbonized. A known method can be used for the carbonization step. The carbonization temperature and elongation rate are appropriately changed according to the target elastic modulus.
このようにして得られた炭素繊維束には、次いで、樹脂との接着性を付与するために、表面処理が施される。表面処理の方法としては、樹脂との接着性を付与できる方法であれば特に限定されないが、例えば、オゾン酸化などの乾式法や、電解液中で電解表面処理する湿式法が挙げられる。 The carbon fiber bundle thus obtained is then subjected to a surface treatment in order to impart adhesion to the resin. The surface treatment method is not particularly limited as long as it is a method capable of imparting adhesiveness to a resin, and examples thereof include a dry method such as ozone oxidation and a wet method in which an electrolytic surface treatment is performed in an electrolytic solution.
表面処理された炭素繊維束には、さらに、サイジング剤が付与される。サイジング剤には、炭素繊維束の取り扱い性や、樹脂との親和性を向上させる働きがある。サイジング剤の種類としては、所望の特性を得ることができれば特に限定されないが、例えば、エポキシ樹脂、ポリエーテル樹脂、エポキシ変性ポリウレタン樹脂、ポリエステル樹脂を主成分としたサイジング剤が挙げられる。 A sizing agent is further applied to the surface-treated carbon fiber bundle. The sizing agent has a function of improving the handleability of the carbon fiber bundle and the affinity with the resin. The type of the sizing agent is not particularly limited as long as desired characteristics can be obtained, and examples thereof include a sizing agent mainly composed of an epoxy resin, a polyether resin, an epoxy-modified polyurethane resin, and a polyester resin.
本発明の炭素繊維の製造方法によれば、炭素繊維束を構成する小繊維束同士がフィラメント単位で絡み合っているため、複合材料の成型過程に用いても、炭素繊維束が合糸前の小繊維束に分かれにくい。ゆえに、本発明からなる炭素繊維を用いれば、安定した品質の複合材料を提供できる。
また、本発明の炭素繊維の製造方法によると、幅広の炭素繊維束を得ることができるので、複合材料の成型過程において、クリールの数を減らすことができる。ゆえに、成型コストを低減させることが可能である。
According to the method for producing carbon fiber of the present invention, since the small fiber bundles constituting the carbon fiber bundle are intertwined in filament units, the carbon fiber bundle is small before being combined even if used in the molding process of the composite material. Difficult to split into fiber bundles. Therefore, when the carbon fiber of the present invention is used, a stable quality composite material can be provided.
Moreover, according to the carbon fiber manufacturing method of the present invention, a wide carbon fiber bundle can be obtained, so that the number of creels can be reduced in the molding process of the composite material. Therefore, the molding cost can be reduced.
次に、本発明の実施例について説明するが、本発明はこれらに限定されるものではない。
＜炭素繊維の製造＞
（実施例１）
１フィラメント当たりの繊度が１．２ｄｔｅｘ、総繊度が１４４００ｄｔｅｘのアクリロニトリル系前駆体繊維を半湿式法で紡糸した。このアクリロニトリル系前駆体繊維（小繊維束）を複数本並べ、溝ロールへ各繊維束を独立して耐炎化炉に導入し、耐炎化時間６０分で、小繊維束の密度が１．３６ｇ／ｃｍ３となるように空気中２２０℃〜２６０℃で耐炎化処理を施した。
この耐炎化工程において、小繊維束の張力を１２５ｍｇ／ｄｔｅｘとし、かつ小繊維束の密度が１．３４ｍｇ／ｃｍ３に達した耐炎化後段の小繊維束２本を、溝ロールに引き揃えて通すことにより合糸することにより、合糸された耐炎化繊維束を得た。
この耐炎化繊維束を１３００℃の窒素雰囲気中で炭素化処理し、炭素繊維束を得た。次いで、この炭素繊維束に２５℃の硝酸アンモニウム１０質量％水溶液中で電解表面処理を施し、さらに、エポキシ樹脂を主成分とするサイジング剤を付与することにより、実施例１の炭素繊維束とした。なお、電解表面処理の電気量は３０クーロン／ｇとした。
Next, examples of the present invention will be described, but the present invention is not limited thereto.
<Manufacture of carbon fiber>
(Example 1)
An acrylonitrile-based precursor fiber having a fineness per filament of 1.2 dtex and a total fineness of 14400 dtex was spun by a semi-wet method. A plurality of the acrylonitrile-based precursor fibers (small fiber bundles) are arranged, and each fiber bundle is independently introduced into the flame-proofing furnace to the groove roll, and the density of the small fiber bundle is 1.36 g / min with a flameproofing time of 60 minutes. The flameproofing treatment was performed at 220 ° C. to 260 ° C. in air so as to be cm 3 .
In this flameproofing process, the tension of the fibril bundle was set to 125 mg / dtex and the density of the fibril bundle reached 1.34 mg / cm 3 and the two fibril bundles after the flame proofing were aligned on the groove roll. By combining the yarns by passing them through, a combined flameproof fiber bundle was obtained.
This flame-resistant fiber bundle was carbonized in a nitrogen atmosphere at 1300 ° C. to obtain a carbon fiber bundle. Next, the carbon fiber bundle was subjected to electrolytic surface treatment in a 10% by mass ammonium nitrate aqueous solution at 25 ° C., and further a sizing agent mainly composed of an epoxy resin was added to obtain the carbon fiber bundle of Example 1. The amount of electricity for the electrolytic surface treatment was 30 coulomb / g.
（実施例２）
小繊維束の張力を１３９ｍｇ／ｄｔｅｘとし、合糸する段階を小繊維束の密度が１．３３ｍｇ／ｃｍ３に達した耐炎化後段に変更した以外は、実施例１と同様にして実施例２の炭素繊維束を得た。
（実施例３）
合糸する段階を小繊維束の密度が１．３５ｍｇ／ｃｍ３に達した耐炎化後段に変更した以外は、実施例１と同様にして実施例３の炭素繊維束を得た。
(Example 2)
Example 2 was carried out in the same manner as in Example 1 except that the tension of the fibril bundle was 139 mg / dtex, and the step of combining yarns was changed to a post-flame-proof stage in which the density of the fibril bundle reached 1.33 mg / cm 3. A carbon fiber bundle was obtained.
(Example 3)
A carbon fiber bundle of Example 3 was obtained in the same manner as in Example 1 except that the step of combining yarns was changed to a post-flame-proofing stage in which the density of the small fiber bundle reached 1.35 mg / cm 3 .
（比較例１）
小繊維束の張力を１２４ｍｇ／ｄｔｅｘとし、合糸する段階を小繊維束の密度が１．２５ｍｇ／ｃｍ３に達した耐炎化中段に変更した以外は、実施例１と同様にして比較例１の炭素繊維束を得た。
（比較例２）
合糸する段階を小繊維束の密度が１．２０ｍｇ／ｃｍ３に達した耐炎化初段に変更した以外は、実施例１と同様にして比較例２の炭素繊維束を得た。
（比較例３）
小繊維束の張力を７０ｍｇ／ｄｔｅｘに変更した以外は、実施例１と同様にして比較例３の炭素繊維束を得た。
（比較例４）
小繊維束の張力を２６０ｍｇ／ｄｔｅｘに変更した以外は、実施例１と同様にして比較例４の炭素繊維束を得た。
（比較例５）
繊維束の張力を７０ｍｇ／ｄｔｅｘとし、合糸する段階を小繊維束の密度が１．３６ｍｇ／ｃｍ３に達して耐炎化工程を経た炭素化工程前に変更した以外は、実施例１と同様にして比較例５の炭素繊維束を得た。
（比較例６）
繊維束の張力を１２０ｍｇ／ｄｔｅｘとし、合糸する段階を小繊維束の密度が１．３６ｍｇ／ｃｍ３に達した耐炎化工程を経た素化工程前に変更した以外は、実施例１と同様にして比較例６の炭素繊維束を得た。
（比較例７）
繊維束の張力を１４０ｍｇ／ｄｔｅｘとし、合糸する段階を小繊維束の密度が１．５９ｍｇ／ｃｍ３に達した炭素化工程中に変更した以外は、実施例１と同様にして比較例７の炭素繊維束を得た。
(Comparative Example 1)
Comparative Example 1 was carried out in the same manner as in Example 1 except that the tension of the fibril bundle was 124 mg / dtex, and the step of combining yarns was changed to the middle flameproofing stage where the density of the fibril bundle reached 1.25 mg / cm 3. A carbon fiber bundle was obtained.
(Comparative Example 2)
A carbon fiber bundle of Comparative Example 2 was obtained in the same manner as in Example 1 except that the step of combining yarns was changed to the flameproofing initial stage in which the density of the small fiber bundle reached 1.20 mg / cm 3 .
(Comparative Example 3)
A carbon fiber bundle of Comparative Example 3 was obtained in the same manner as in Example 1 except that the tension of the small fiber bundle was changed to 70 mg / dtex.
(Comparative Example 4)
A carbon fiber bundle of Comparative Example 4 was obtained in the same manner as in Example 1 except that the tension of the small fiber bundle was changed to 260 mg / dtex.
(Comparative Example 5)
Example 1 except that the tension of the fiber bundle was set to 70 mg / dtex, and the step of combining was changed before the carbonization step through which the density of the small fiber bundle reached 1.36 mg / cm 3 and passed through the flameproofing step. Thus, a carbon fiber bundle of Comparative Example 5 was obtained.
(Comparative Example 6)
Example 1 except that the tension of the fiber bundle was set to 120 mg / dtex, and the step of combining yarns was changed before the raw material process through the flameproofing process in which the density of the small fiber bundle reached 1.36 mg / cm 3. Thus, a carbon fiber bundle of Comparative Example 6 was obtained.
(Comparative Example 7)
Comparative Example 7 was carried out in the same manner as in Example 1 except that the tension of the fiber bundle was 140 mg / dtex and the step of combining was changed during the carbonization process in which the density of the small fiber bundle reached 1.59 mg / cm 3. A carbon fiber bundle was obtained.
＜評価方法＞
実施例１〜３、比較例１〜５、及び比較例７で得た炭素繊維束それぞれについて、両手で炭素繊維束の幅方向に引き裂くように引っ張り、合糸される前の小繊維束に分かれるか否かを評価した。小繊維束同士が分かれない例、すなわち、合糸性の良い例を○とし、小繊維束に分かれた例、すなわち、合糸性の悪かった例を×とした。結果を表１に示す。
また、実施例１〜３、比較例１〜５、及び比較例７の炭素繊維束それぞれについて、外観上の毛羽の発生を目視にて確認し、毛羽の発生の少ない例、すなわち、毛羽品位の高い例を○とし、毛羽の発生の多い例、すなわち、毛羽品位の低い例を×とした。結果を表１に示す。
<Evaluation method>
About each of the carbon fiber bundles obtained in Examples 1 to 3, Comparative Examples 1 to 5, and Comparative Example 7, the carbon fiber bundles are pulled with both hands so as to tear in the width direction, and are divided into small fiber bundles before being combined. It was evaluated whether or not. An example in which the fibril bundles were not separated, that is, an example having good pliability, was marked with ◯, and an example in which the fibril bundles were separated, that is, an example with poor pliability was marked with x. The results are shown in Table 1.
In addition, for each of the carbon fiber bundles of Examples 1 to 3, Comparative Examples 1 to 5, and Comparative Example 7, the occurrence of fluff on the appearance was confirmed by visual observation. A high example was marked with ◯, and an example with a lot of fluff generation, that is, an example with low fluff quality was marked with ×. The results are shown in Table 1.
＜評価＞
実施例１〜３は合糸前の小繊維束２本に分かれることなく、合糸性が良好と確認された。また毛羽の程度が少なく、毛羽品位が良好であると確認された。
比較例３、５、及び７は、毛羽品位が良好であるものの、合糸される前の小繊維束２本に分かれてしまったため、合糸性が悪いと確認された。また、比較例１、２、及び４は、合糸性が良好であるものの、毛羽が多いため、毛羽品位が低いと確認された。
なお、比較例６の炭素繊維束は、合糸の段階において、高張力によるトウ切れを生じたため、評価を行えなかった。
<Evaluation>
Examples 1 to 3 were confirmed to have good pliability without being divided into two small fiber bundles before merging. Further, it was confirmed that the degree of fluff was small and the fluff quality was good.
In Comparative Examples 3, 5, and 7, although the fluff quality was good, it was confirmed that the pliability was poor because it was divided into two small fiber bundles before being plied. Further, Comparative Examples 1, 2, and 4 were confirmed to have low fluff quality because they had good fusing properties but had a lot of fluff.
Note that the carbon fiber bundle of Comparative Example 6 could not be evaluated because a tow break due to high tension occurred at the stage of the combined yarn.
本発明の炭素繊維の製造方法によれば、安定した繊維配列を有する幅広の炭素繊維束を得ることができる。ゆえに、本発明からなる炭素繊維を用いれば、炭素繊維を用いた複合材料の品質を安定させることができる。
また、本発明の炭素繊維の製造方法によれば、幅広の炭素繊維束を得ることができるので、炭素繊維を用いた複合材料の成型過程において、クリールの数を減らすことができる。ゆえに、複合材料の成型コストを低減させることが可能である。
According to the carbon fiber manufacturing method of the present invention, a wide carbon fiber bundle having a stable fiber arrangement can be obtained. Therefore, if the carbon fiber which consists of this invention is used, the quality of the composite material using carbon fiber can be stabilized.
In addition, according to the carbon fiber manufacturing method of the present invention, a wide carbon fiber bundle can be obtained, so that the number of creels can be reduced in the molding process of a composite material using carbon fibers. Therefore, the molding cost of the composite material can be reduced.
Claims (2)
耐炎化工程中に、前記前駆体繊維からなる小繊維束にかける張力が１０４〜２４３ｍｇ／ｄｔｅｘの範囲内で、かつ前記小繊維束の密度が１．３１〜１．３７ｍｇ／ｃｍ３の範囲内で、複数の小繊維束を溝ロールに導入して合糸することを特徴とする炭素繊維の製造方法。 In a method for producing a carbon fiber having a flameproofing step of flameproofing a precursor fiber in a flameproofing furnace and a carbonization step of carbonizing the flameproofed fiber after the flameproofing step in a carbonization furnace,
During the flameproofing step, the tension applied to the fibril bundle composed of the precursor fibers is within the range of 104 to 243 mg / dtex, and the density of the fibril bundle is within the range of 1.31 to 1.37 mg / cm 3 . A method for producing carbon fiber, wherein a plurality of small fiber bundles are introduced into a groove roll and combined.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61119719A (en) * | 1984-11-14 | 1986-06-06 | Toho Rayon Co Ltd | Production of carbon fiber of high strength |
| JP3448994B2 (en) * | 1994-12-01 | 2003-09-22 | 東レ株式会社 | Carbon fiber bundle and method for producing the same |
| JP2005281883A (en) * | 2004-03-29 | 2005-10-13 | Toray Ind Inc | Method for producing flameproofed fiber and carbon fiber |
| JP2006274507A (en) * | 2005-03-30 | 2006-10-12 | Toray Ind Inc | Flame resistant fiber |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61119719A (en) * | 1984-11-14 | 1986-06-06 | Toho Rayon Co Ltd | Production of carbon fiber of high strength |
| JP3448994B2 (en) * | 1994-12-01 | 2003-09-22 | 東レ株式会社 | Carbon fiber bundle and method for producing the same |
| JP2005281883A (en) * | 2004-03-29 | 2005-10-13 | Toray Ind Inc | Method for producing flameproofed fiber and carbon fiber |
| JP2006274507A (en) * | 2005-03-30 | 2006-10-12 | Toray Ind Inc | Flame resistant fiber |
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