JP2014025167A - Flame-resistant fiber bundle and carbon fiber bundle, and methods for producing the same - Google Patents
Flame-resistant fiber bundle and carbon fiber bundle, and methods for producing the same Download PDFInfo
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本発明は、耐炎化繊維束および炭素繊維束、ならびにそれらの製造方法に関し、さらに詳しくは、ストランド強度で代表される引張強度の高い炭素繊維束の製造に用いられる耐炎化繊維束およびその製造方法、ならびに当該耐炎化繊維束を用いて得られる高引張強度の炭素繊維束およびその製造方法に関する。 The present invention relates to a flame-resistant fiber bundle, a carbon fiber bundle, and a method for producing the same, and more specifically, a flame-resistant fiber bundle used for producing a carbon fiber bundle having a high tensile strength represented by strand strength and a method for producing the same. And a carbon fiber bundle having a high tensile strength obtained by using the flame-resistant fiber bundle and a method for producing the same.
炭素繊維は比強度、比弾性率に優れていることから、航空・宇宙産業をはじめ、釣竿、テニスラケットなどのスポーツ用途、風力発電のブレードや自動車など一般産業用途と幅広い分野で使用されている。 Since carbon fiber has excellent specific strength and specific modulus, it is used in a wide range of fields such as aerospace industry, sports applications such as fishing rods and tennis rackets, and general industrial applications such as wind power blades and automobiles. .
ポリアクリロニトリル系炭素繊維束の製造方法は、一般にポリアクリロニトリル系繊維束を酸化性気体雰囲気下で２００〜３００℃で加熱して耐炎化繊維束を得て、次いで不活性ガス雰囲気下１２００℃以上で加熱して得られる。ポリアクリロニトリル系繊維束は通常１０００〜８００００本の単糸からなるが、耐炎化工程での単糸同士の融着を防止するため、ポリアクリロニトリル系繊維束にシリコーン系油剤を付与する方法が広く知られている。シリコーン系油剤は耐熱性に優れ、単糸同士の融着の防止に効果的を発揮する一方、シリコーン系油剤は加熱されると酸化されて粉塵になり、単糸に傷を付けるなどの悪影響を及ぼすというデメリットがある。 In general, a polyacrylonitrile-based carbon fiber bundle is manufactured by heating a polyacrylonitrile-based fiber bundle at 200 to 300 ° C. in an oxidizing gas atmosphere to obtain a flame-resistant fiber bundle, and then in an inert gas atmosphere at 1200 ° C. or higher. Obtained by heating. Polyacrylonitrile fiber bundles are usually composed of 1000 to 80000 single yarns. In order to prevent fusion of single yarns in the flameproofing process, a method of applying a silicone-based oil to polyacrylonitrile fiber bundles is widely known. It has been. Silicone-based oils have excellent heat resistance and are effective in preventing the fusion of single yarns.On the other hand, silicone-based oils are oxidized and become dust when heated. There is a demerit that it affects.
耐炎化炉において、ファンにより循環流路を循環する酸化性気体、代表的には空気は、循環ダクト内に設けられたヒーターおよびその制御機構により炉内温度が一定になるよう制御されており、ポリアクリロニトリル系繊維束は炉内を多段のローラーで折り返されながら所定の温度で加熱処理される。 In the flameproofing furnace, the oxidizing gas, typically air, circulated through the circulation flow path by the fan is controlled so that the furnace temperature becomes constant by the heater provided in the circulation duct and its control mechanism. The polyacrylonitrile fiber bundle is heat-treated at a predetermined temperature while being folded back by a multistage roller in the furnace.
ポリアクリロニトリル系繊維束の耐炎化処理において熱風循環を繰返すうちに、熱風には、ストランド由来のケバや粉末等の異物が蓄積し、耐炎化繊維束を汚染するようになることが知られている （特許文献１）。 While the hot air circulation is repeated in the flameproofing treatment of the polyacrylonitrile fiber bundle, it is known that the hot air accumulates foreign matters such as strands and powders from the strands and contaminates the flameproof fiber bundle. (Patent Document 1).
この課題や、生産開始直後の操業・品質を安定させる手段として、特許文献１、２には耐炎化炉内を循環する酸化雰囲気をフィルタに通すことにより、異物や粉塵を除去して、炭素繊維束の引張強度を安定化させる方法が開示されている。しかしながら、異物や粉塵をフィルタで除去しても、工業的に許容できる生産性を保ちながら、完全に粉塵を除去することは困難であり、また、そのような状態の元で加熱気体に存在する異物や粉塵の数と、耐炎化の条件の関係や、好ましい耐炎化繊維束の状態については、検討されていなかった。 As a means to stabilize the operation and quality immediately after the start of production, Patent Documents 1 and 2 disclose that carbon fiber is used to remove foreign matters and dust by passing an oxidizing atmosphere circulating in the flameproofing furnace through a filter. A method for stabilizing the tensile strength of a bundle is disclosed. However, even if foreign matter and dust are removed with a filter, it is difficult to completely remove dust while maintaining industrially acceptable productivity, and it exists in the heated gas under such a state. The relationship between the number of foreign substances and dust and the flameproofing conditions and the preferable state of the flameproofed fiber bundle have not been studied.
また、特許文献３では、長期にわたって耐炎化工程を稼動させ続けることは困難であり、頻繁に稼動を停止して、炉内清掃を行う必要があることを課題としてあげ、その課題を解決するために、耐炎化繊維束に付着した微粒子を、界面活性剤を含有する液体中で超音波洗浄などを用いて除去する方法などが開示されている。しかしながら、特許文献３に記載された方法では、超音波処理工程において、微粒子が表面に新しく欠陥を生じる可能性がある上、界面活性剤の完全な除去は困難であるため、微量でも糸に残留した残渣は、後の炭素化工程で１２００℃以上に加熱されたときに、異物による不均一な反応を生じ、クリーン化の効果が限定的であった。また、この方法は、耐炎化処理が終わった糸に付着している微粒子を除去する方法であるため、原理的に耐炎化炉内で微粒子によってすでに傷を生じている場合は引張強度の低下を防ぐことはできず、効果は限定的であるといえる。 Further, in Patent Document 3, it is difficult to keep the flameproofing process in operation for a long time, and it is necessary to stop the operation frequently and perform cleaning in the furnace, in order to solve the problem In addition, a method of removing fine particles adhering to the flame-resistant fiber bundle using ultrasonic cleaning or the like in a liquid containing a surfactant is disclosed. However, in the method described in Patent Document 3, in the ultrasonic treatment process, fine particles may newly cause defects on the surface, and it is difficult to completely remove the surfactant. When the residue was heated to 1200 ° C. or higher in the subsequent carbonization step, a non-uniform reaction due to foreign matter occurred, and the effect of cleaning was limited. In addition, this method is a method for removing the fine particles adhering to the yarn that has been subjected to flameproofing treatment. Therefore, in principle, if the scratches are already caused by the fine particles in the flameproofing furnace, the tensile strength is reduced. It cannot be prevented and the effect is limited.
上述の汚染は、熱風循環炉である耐炎化炉内では、シリコーン系油剤が揮発しヒーターなどで加熱・酸化されることで粉塵へと変化したり、周辺外気から、砂等の微粒子が混入したり、耐炎化炉および周辺装置の内面に錆を生じるなどによって金属元素を含む微粒子が侵入したり、さらには、シリコーン系油剤やポリアクリロニトリル系繊維束そのものから発生するタール成分が固化したものなどが連続生産により炉内に溜まったりすることによって、長期の生産に伴い耐炎化炉内には多くの粉塵等の微粒子が堆積することによるものであることが知られている。これらの粉塵等の微粒子は、酸化性気体からなる熱風とともに炉内を循環し、耐炎化繊維束に付着して繊維の毛羽立ちや単糸切れなどを引き起こすほか、毛羽などには至らないものの単糸に物理的な傷を与えて炭素繊維束の引張強度の低下などを招いたり、金属元素を含む微粒子が糸に付着して、耐炎化工程以降で、炭素などとの化学反応による欠陥を引き起こしたりする原因となる。これらの微粒子は、耐炎化工程およびそれ以降で反応するか、脱落して消失したり、その後の表面処理・水洗工程で洗い流されたりする場合があり、炭素繊維束では検出できない可能性があるが、中間物である耐炎化繊維束にはこれらの微粒子が付着したままであるか、脱落していても既に傷を生じており、品質低下の原因となる微粒子や傷が観察可能である。また、半月〜１年の長期間生産を続ければ、炉内に蓄積される粉塵等の微粒子の量は増大するため、糸に付着する微粒子や傷などの欠陥の数は増え、上記の微粒子や異物による品質問題はさらに顕著になる。 In the flameproofing furnace, which is a hot-air circulating furnace, the above-mentioned contamination is changed to dust by volatilizing the silicone-based oil agent and being heated and oxidized by a heater, etc., and fine particles such as sand are mixed in from the outside air. In addition, fine particles containing metal elements may invade due to rusting on the inner surfaces of flameproofing furnaces and peripheral devices, and further, solidified tar components generated from silicone oils or polyacrylonitrile fiber bundles themselves. It is known that accumulation of fine particles such as dust in the flameproofing furnace accompanies long-term production due to accumulation in the furnace due to continuous production. These fine particles such as dust circulate in the furnace together with hot air made of oxidizing gas, adhere to the flame-resistant fiber bundle and cause fiber fluffing and single yarn breakage, etc. This may cause physical damage to the fiber, leading to a decrease in the tensile strength of the carbon fiber bundle, or fine particles containing metal elements may adhere to the thread, causing defects due to chemical reaction with carbon after the flame resistance process. Cause. These fine particles may react in the flameproofing process and thereafter, or may drop off and disappear, or may be washed away in the subsequent surface treatment / water washing process, and may not be detected by the carbon fiber bundle. The flame-resistant fiber bundle, which is an intermediate product, has already been attached to the flame-resistant fiber bundle, or has already been damaged even if it has fallen off, and it is possible to observe the fine particles and scratches that cause a reduction in quality. In addition, if production is continued for half a month to one year, the amount of fine particles such as dust accumulated in the furnace increases, so the number of fine particles and defects such as scratches adhering to the yarn increases. The quality problem due to foreign matters becomes even more pronounced.
毛羽立ち・糸切れや炭素繊維束の品質の低下が一定レベル以上に悪化するのを防ぐには、耐炎化糸束における単糸に付着する粉塵等の微粒子の数と生じる傷などの数を減らすことが重要であり、できるだけ長期に生産ラインを停機せず安定した操業状態と、その耐炎糸束を炭化したときの品質を安定化させる技術が要望されている。 To prevent the fluffing, yarn breakage, and deterioration of the quality of the carbon fiber bundle from deteriorating beyond a certain level, reduce the number of fine particles such as dust adhering to the single yarn in the flame-resistant yarn bundle and the number of scratches that occur. Therefore, there is a demand for a technology that stabilizes the operation state without stopping the production line for as long as possible and the quality when the flame resistant yarn bundle is carbonized.
本発明の課題は、耐炎化繊維束および炭素繊維束の製造において、熱処理炉内の微粒子の濃度や熱処理炉中の繊維束の幅、風量などを特定の範囲に制御することで、単糸に生じる傷や単糸表面に付着する粉塵などの微粒子の少ない耐炎化繊維束を製造し、炭素繊維束の生産開始初期から長期間にわたって、安定した操業性で、品質的に安定した連続生産を可能にすることである。 The object of the present invention is to produce a single yarn by controlling the concentration of fine particles in the heat treatment furnace, the width of the fiber bundle in the heat treatment furnace, the air volume, etc. in a specific range in the production of the flameproof fiber bundle and the carbon fiber bundle. Produces a flame-resistant fiber bundle with few fine particles such as scratches and dust adhering to the surface of the single yarn, and enables stable continuous production with stable operability from the beginning of the production of the carbon fiber bundle for a long period of time. Is to do.
かかる課題を解決するための本発明は、以下の構成からなる。
（１）粒径０．３μｍ以上の微粒子の濃度が３００〜２５００個／リットルである酸化性気体を、アミノ変性シリコーンを含むシリコーン系油剤が付与された単糸繊度０．４〜１．６ｄｔｅｘ、フィラメント数１０００〜８００００本のポリアクリロニトリル系繊維束の走行方向と垂直に循環させる熱処理炉で、該ポリアクリロニトリル系繊維束を２００〜３００℃で加熱処理をするに際し、
［Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］ （式１）
の値が５〜４０である条件下で加熱処理することを特徴とする耐炎化繊維束の製造方法。
The present invention for solving this problem has the following configuration.
(1) Single yarn fineness of 0.4 to 1.6 dtex to which an oxidizing gas having a particle size of 0.3 μm or more having a concentration of 300 to 2500 particles / liter is provided with a silicone-based oil containing amino-modified silicone, When heat-treating the polyacrylonitrile fiber bundle at 200 to 300 ° C. in a heat treatment furnace circulating in a direction perpendicular to the traveling direction of the polyacrylonitrile fiber bundle having 1000 to 80000 filaments,
[D × (W × V × L)] / [(S / 60) × 10 5 ] (Formula 1)
A method for producing a flame-resistant fiber bundle, wherein the heat treatment is carried out under the condition of a value of 5 to 40.
但し、（式１）において、
Ｄ：前記熱処理炉内に存在する粒径０．３μｍ以上の微粒子の濃度［個／リットル］
Ｗ：以下に定義される繊維束の幅［ｃｍ／ストランド］
Ｖ：繊維束を通過する循環熱風の風速［ｍ／秒］
Ｌ：繊維束が通過する炉長をＬ［ｍ］
Ｓ：繊維束の炉内通過速度［ｍ／分］である。
（２）熱処理炉内を循環する酸化性気体に含まれる粒径０．３μｍ以上の微粒子の濃度を、集塵装置を用いて３００〜６００個／リットルに保つ、（１）に記載の耐炎化繊維束の製造方法。
（３）（１）または（２）に記載の方法で得られた耐炎化繊維束を、不活性雰囲気下、１２００℃以上で加熱処理することを特徴とする炭素繊維束の製造方法。
（４）（１）または（２）に記載の方法で得られた耐炎化繊維束であって、単糸繊度が１．０ｄｔｅｘ以下の耐炎化繊維束を、不活性雰囲気下、１３００℃以上で加熱処理することを特徴とする炭素繊維束の製造方法。
（５）ポリアクリロニトリル系繊維束を、酸化性気体を循環する熱処理炉で２００〜３００℃で加熱して得られる、単糸直径が６〜１３μｍ、以下に定義される繊維束の糸幅が１糸条あたり０．５〜１．０ｃｍ、密度が１．３４〜１．４０ｇ／ｃｍ３の耐炎化繊維束であって、以下に定義される単糸表面に観察されるＳｉ、Ｃ、Ｎａ、Ｍｇ、Ａｌ、Ｋ、Ｃａ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｚｎのいずれかを主成分とし、かつ粒径が０．３μｍ以上である微粒子の個数と、以下に定義される０．３μｍ以上の単糸表面の傷の個数の合計が、観察面積０．１ｍｍ２あたり１５個以下であることを特徴とする耐炎化繊維束。
（６）耐炎化繊維束の単糸の算術平均表面粗さＲａが１〜２０ｎｍ、単糸繊度が０．４〜１．７ｄｔｅｘである、（５）に記載の耐炎化繊維束。
（７）（５）または（６）に記載の耐炎化繊維束を、不活性雰囲気下、１２００℃以上で加熱処理して得られる、引張強度が４．７ＧＰａ以上、引張弾性率が２００ＧＰａ以上である炭素繊維束。
（８）（５）または（６）に記載の耐炎化繊維束であって、単糸繊度が１．０ｄｔｅｘ以下の耐炎化繊維束を、不活性雰囲気下、１３００℃以上で加熱処理して得られる、引張強度が５．５ＧＰａ以上、引張弾性率が２８０ＧＰａ以上である炭素繊維束。
（９）粒径０．３μｍ以上の微粒子の個数が３００〜２５００個／リットルである酸化性気体を、アミノ変性シリコーンを含むシリコーン系油剤が付与されたポリアクリロニトリル系繊維束の走行方向と垂直に循環させる熱処理炉で、該ポリアクリロニトリル系繊維束を２００〜３００℃で加熱処理をするに際し、
［Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］ （式１）
の値が５〜４０である条件下で加熱処理することによって、単糸直径が６〜１３μｍ、以下に定義される繊維束の糸幅が１糸条あたり０．５〜１．０ｃｍ、密度が１．３４〜１．４０ｇ／ｃｍ３の耐炎化繊維束を得る方法であって、該耐炎化繊維束は、以下に定義される単糸表面に観察されるＳｉ、Ｃ、Ｎａ、Ｍｇ、Ａｌ、Ｋ、Ｃａ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｚｎのいずれかを主成分とし、かつ粒径が０．３μｍ以上である微粒子の個数と、以下に定義される０．３μｍ以上の単糸表面の傷の個数の合計が観察面積０．１ｍｍ２あたり１５個以下であることを特徴とする耐炎化繊維束の製造方法
但し、（式１）において、
Ｄ：前記熱処理炉内に存在する粒径０．３μｍ以上の微粒子の濃度［個／リットル］
Ｗ：以下に定義される繊維束の幅［ｃｍ／ストランド］
Ｖ：繊維束を通過する循環熱風の風速［ｍ／秒］
Ｌ：繊維束が通過する炉長をＬ［ｍ］
Ｓ：繊維束の炉内通過速度［ｍ／分］である。
（１０）前記耐炎化繊維束の単糸の算術平均表面粗さＲａが１〜２０ｎｍ、単糸繊度が０．４〜１．７ｄｔｅｘである（９）に記載の耐炎化繊維束の製造方法。
（１１）（９）または（１０）に記載の方法で得られた耐炎化繊維束を、不活性雰囲気下、１２００℃以上で加熱処理する炭素繊維束の製造方法であって、該炭素繊維束は、耐炎化炉を清掃せずに連続生産する全期間において引張強度が４．７ＧＰａ以上、引張弾性率が２００ＧＰａ以上であることを特徴とする炭素繊維束の製造方法。
（１２）（９）または（１０）に記載の方法で得られた耐炎化繊維束であって、単糸繊度が１．０ｄｔｅｘ以下の耐炎化繊維束を、不活性雰囲気下、１３００℃以上で加熱処理する炭素繊維束の製造方法であって、該炭素繊維束は、耐炎化炉を清掃せずに連続生産する全期間において引張強度が５．５ＧＰａ以上、引張弾性率が２８０ＧＰａ以上であることを特徴とする炭素繊維束の製造方法。
However, in (Formula 1):
D: Concentration of particles having a particle size of 0.3 μm or more existing in the heat treatment furnace [piece / liter]
W: width of the fiber bundle defined below (cm / strand)
V: Wind speed of circulating hot air passing through the fiber bundle [m / sec]
L: The furnace length through which the fiber bundle passes is L [m]
S: The passing speed of the fiber bundle in the furnace [m / min].
(2) The flame resistance according to (1), wherein the concentration of fine particles having a particle size of 0.3 μm or more contained in the oxidizing gas circulating in the heat treatment furnace is maintained at 300 to 600 particles / liter using a dust collector. A method of manufacturing a fiber bundle.
(3) A method for producing a carbon fiber bundle, comprising heat-treating the flame-resistant fiber bundle obtained by the method according to (1) or (2) at 1200 ° C. or higher in an inert atmosphere.
(4) A flame-resistant fiber bundle obtained by the method according to (1) or (2), wherein the flame-resistant fiber bundle having a single yarn fineness of 1.0 dtex or less is 1300 ° C. or higher in an inert atmosphere. A method for producing a carbon fiber bundle, characterized by heat treatment.
(5) A polyacrylonitrile fiber bundle is obtained by heating at 200 to 300 ° C. in a heat treatment furnace in which an oxidizing gas is circulated. The single yarn diameter is 6 to 13 μm, and the yarn width of the fiber bundle defined below is 1. A flame-resistant fiber bundle having a density of 0.5 to 1.0 cm per yarn and a density of 1.34 to 1.40 g / cm 3 , which is observed on the surface of the single yarn defined below, Si, C, Na, The number of fine particles having Mg, Al, K, Ca, Mn, Fe, Co, Ni, or Zn as a main component and having a particle size of 0.3 μm or more, and 0.3 μm or more as defined below A flame-resistant fiber bundle, wherein the total number of scratches on the surface of the single yarn is 15 or less per observation area of 0.1 mm 2 .
(6) The flame-resistant fiber bundle according to (5), wherein the single yarn has an arithmetic average surface roughness Ra of 1 to 20 nm and a single yarn fineness of 0.4 to 1.7 dtex.
(7) The flame-resistant fiber bundle according to (5) or (6) is obtained by heat treatment at 1200 ° C. or higher in an inert atmosphere, and has a tensile strength of 4.7 GPa or more and a tensile modulus of 200 GPa or more. A carbon fiber bundle.
(8) A flame-resistant fiber bundle according to (5) or (6), which is obtained by heat-treating a flame-resistant fiber bundle having a single yarn fineness of 1.0 dtex or less at 1300 ° C. or higher in an inert atmosphere. A carbon fiber bundle having a tensile strength of 5.5 GPa or more and a tensile elastic modulus of 280 GPa or more.
(9) An oxidizing gas having a particle size of 0.3 μm or more of 300 to 2500 / liter is perpendicular to the running direction of the polyacrylonitrile fiber bundle to which a silicone oil containing amino-modified silicone is applied. When the polyacrylonitrile fiber bundle is heat-treated at 200 to 300 ° C. in a circulating heat treatment furnace,
[D × (W × V × L)] / [(S / 60) × 10 5 ] (Formula 1)
By performing heat treatment under the condition of a value of 5 to 40, the single yarn diameter is 6 to 13 μm, the yarn width of the fiber bundle defined below is 0.5 to 1.0 cm per yarn, and the density is 1. A method of obtaining a flame-resistant fiber bundle of 1.34 to 1.40 g / cm 3, wherein the flame-resistant fiber bundle is observed on the surface of a single yarn defined below, Si, C, Na, Mg, Al , K, Ca, Mn, Fe, Co, Ni, Zn, and the number of fine particles having a particle size of 0.3 μm or more and the surface of a single yarn of 0.3 μm or more as defined below The total number of scratches is 15 or less per 0.1 mm 2 of the observation area. A method for producing a flame-resistant fiber bundle, wherein (Equation 1):
D: Concentration of particles having a particle size of 0.3 μm or more existing in the heat treatment furnace [piece / liter]
W: width of the fiber bundle defined below (cm / strand)
V: Wind speed of circulating hot air passing through the fiber bundle [m / sec]
L: The furnace length through which the fiber bundle passes is L [m]
S: The passing speed of the fiber bundle in the furnace [m / min].
(10) The method for producing a flame resistant fiber bundle according to (9), wherein the arithmetic average surface roughness Ra of the single yarn of the flame resistant fiber bundle is 1 to 20 nm and the single yarn fineness is 0.4 to 1.7 dtex.
(11) A method for producing a carbon fiber bundle, wherein the flame-resistant fiber bundle obtained by the method according to (9) or (10) is heat-treated at 1200 ° C. or higher in an inert atmosphere, the carbon fiber bundle Is a method for producing a carbon fiber bundle, wherein the tensile strength is 4.7 GPa or more and the tensile elastic modulus is 200 GPa or more over the entire period of continuous production without cleaning the flameproofing furnace.
(12) A flame-resistant fiber bundle obtained by the method according to (9) or (10), wherein the flame-resistant fiber bundle having a single yarn fineness of 1.0 dtex or less is 1300 ° C. or higher in an inert atmosphere. A method for producing a carbon fiber bundle to be heat-treated, wherein the carbon fiber bundle has a tensile strength of 5.5 GPa or more and a tensile elastic modulus of 280 GPa or more over the entire period of continuous production without cleaning the flameproofing furnace. A method for producing a carbon fiber bundle characterized by the above.
本発明は、熱処理炉内の微粒子の濃度や耐炎化繊維束の糸幅、風量などを特定の範囲に制御することで、熱処理炉内に存在する粉塵等の微粒子が耐炎化繊維束に付着するのを一定の割合以下に防止することができ、さらに、生産開始から終了までの微粒子付着物と傷の数などの品質に影響する要因を一定の範囲に保つことが可能となり、長期間に安定した耐炎化繊維束の連続生産が可能となる。 In the present invention, fine particles such as dust existing in the heat treatment furnace adhere to the flame resistant fiber bundle by controlling the concentration of the fine particles in the heat treatment furnace, the yarn width of the flame resistant fiber bundle, the air volume, and the like within a specific range. In addition, it is possible to keep the factors affecting quality such as the number of fine particles and scratches from the start to the end of production within a certain range, and stable for a long period of time. It is possible to continuously produce flame-resistant fiber bundles.
また、本発明で得られる耐炎化繊維束を不活性雰囲気下で熱処理して得られる炭素繊維束は、長期間の生産を行っても安定的に高い引張強度を得ることが出来る。 Moreover, the carbon fiber bundle obtained by heat-treating the flame-resistant fiber bundle obtained in the present invention under an inert atmosphere can stably obtain a high tensile strength even if it is produced for a long time.
本発明において原料として用いられるポリアクリロニトリル系繊維束は、アクリル系重合体として、アクリルニトリルの単独重合体あるいは共重合体を、有機または無機溶媒を用いて紡糸することで得られる。 The polyacrylonitrile fiber bundle used as a raw material in the present invention is obtained by spinning an acrylonitrile homopolymer or copolymer as an acrylic polymer using an organic or inorganic solvent.
本発明で使用されるポリアクリロニトリル系繊維束の製造方法には特に制限がないが、湿式紡糸または乾湿式紡糸が好ましく用いられ、その後、延伸、水洗、油剤付与、乾燥緻密化，必要あれば後延伸などの工程を経て得ることができる。 There is no particular limitation on the method for producing the polyacrylonitrile fiber bundle used in the present invention, but wet spinning or dry-wet spinning is preferably used, and then stretching, washing with water, oiling, drying and densification, if necessary It can be obtained through a process such as stretching.
本発明で使用されるポリアクリロニトリル系繊維束は、耐炎化して耐炎化繊維束を得た際に、単糸の算術平均表面粗さがＲａで表して１〜２０ｎｍとなることが好ましい。より好ましい耐炎化繊維束の単糸の算術平均表面粗さＲａの範囲は２〜１５ｎｍである。算術平均表面粗さＲａを１ｎｍ以上とすることによって、過度の集束性を押さえ単糸同士の接着を防ぐことが可能となる。また２０ｎｍ以下とすることによって、長期間運転しても糸条が開繊して毛羽立ちし、極端な場合は引張強度が低下することを防ぐことができる。 When the polyacrylonitrile fiber bundle used in the present invention is flame-resistant to obtain a flame-resistant fiber bundle, the arithmetic average surface roughness of the single yarn is preferably 1 to 20 nm in terms of Ra. A more preferable range of the arithmetic average surface roughness Ra of the single yarn of the flame-resistant fiber bundle is 2 to 15 nm. By setting the arithmetic average surface roughness Ra to 1 nm or more, it becomes possible to suppress excessive convergence and prevent adhesion of single yarns. Moreover, by setting it as 20 nm or less, it is possible to prevent the yarn from opening and fluffing even when operated for a long period of time, and in the extreme case, the tensile strength can be prevented from decreasing.
これらの耐炎化繊維束は、原料として用いられるポリアクリロニトリル系繊維束を製糸する際に、そのポリマー重合度、溶媒濃度、共重合組成を決定した後、口金から凝固浴にポリマーを吐出する際、凝固の実質ドラフト、すなわちポリマーが凝固する際に繊維軸方向に掛かる張力が小さくなる条件を選定した後、通常の延伸、乾燥条件の中から選定して、単糸の算術平均表面粗さが１ｎｍ以上、２０ｎｍ以下のアクリル繊維束を製造し、耐炎化することによって好適に達成される。なお、この耐炎化繊維束を構成する単糸の算術平均表面粗さによって、得られる炭素繊維束の表面粗さも決定されることが一般的である。実質ドラフトを小さくする条件は、乾湿式紡糸によるか、湿式紡糸による場合は,凝固浴からの引取速度と、口金から吐出される重合体の線速度との比、すなわち計算ドラフトを１．０以下好ましくは０．８以下にして達成が可能である。 These flame-resistant fiber bundles are used when a polyacrylonitrile fiber bundle used as a raw material is produced, and after determining the polymer polymerization degree, solvent concentration and copolymer composition, when discharging the polymer from the die to the coagulation bath, After selecting the conditions for the substantial draft of solidification, that is, the condition that the tension applied in the fiber axis direction is reduced when the polymer is solidified, the condition is selected from the normal drawing and drying conditions, and the arithmetic average surface roughness of the single yarn is 1 nm. As mentioned above, it is suitably achieved by producing an acrylic fiber bundle of 20 nm or less and making it flame resistant. In general, the surface roughness of the obtained carbon fiber bundle is also determined by the arithmetic average surface roughness of the single yarn constituting the flameproof fiber bundle. The condition for reducing the substantial draft is dry / wet spinning or, in the case of wet spinning, the ratio between the take-up speed from the coagulation bath and the linear speed of the polymer discharged from the die, that is, the calculated draft is 1.0 or less. Preferably, it can be achieved with 0.8 or less.
本発明で使用されるポリアクリロニトリル系繊維束は、単糸繊度が０．４〜１．６ｄｔｅｘであって、フィラメント数が１０００〜８００００であることが必要である。また、これを用いて得られる耐炎化繊維束の単糸直径が６〜１３μｍであることが好ましく、単糸の数は１２０００〜５００００本であることが好ましい。 The polyacrylonitrile fiber bundle used in the present invention needs to have a single yarn fineness of 0.4 to 1.6 dtex and a number of filaments of 1000 to 80000. Moreover, it is preferable that the single yarn diameter of the flameproof fiber bundle obtained using this is 6-13 micrometers, and it is preferable that the number of single yarns is 12000-50000.
本発明で使用されるポリアクリロニトリル系繊維束に付与されるシリコーン系油剤には、少なくともその一部にアミノ変性シリコーンを含む必要がある。ポリアクリロニトリル系繊維束に付与するシリコーン系油剤の付着量は、好ましくは０．０５〜３質量％、より好ましくは０．３〜１．５質量％である。かかるシリコーン系油剤には、さらに界面活性剤、熱安定剤などが加えられていてもよい。また、シリコーン系油剤の種類としては、ジメチルシロキサンならびにそれらを官能基で変性したものが好ましく用いられ、必須成分としてアミノ基で変性したアミノ変性ジメチルシロキサンを含むほか、ポリエチレンオキシド変性ジメチルシロキサンや、エポキシ変性ジメチルシロキサンと混合して用い、熱安定性を増加したものがより好ましい。 The silicone-based oil applied to the polyacrylonitrile fiber bundle used in the present invention needs to contain amino-modified silicone at least in part. The adhesion amount of the silicone oil applied to the polyacrylonitrile fiber bundle is preferably 0.05 to 3% by mass, more preferably 0.3 to 1.5% by mass. Such silicone oil may further contain a surfactant, a heat stabilizer and the like. As the types of silicone oils, dimethyl siloxane and those modified with functional groups are preferably used, including amino-modified dimethyl siloxane modified with amino groups as essential components, polyethylene oxide-modified dimethyl siloxane, epoxy It is more preferable to use a mixture with modified dimethylsiloxane to increase the thermal stability.
シリコーン系油剤は、予め１０５℃・５時間乾燥した油剤成分を、熱天秤分析によって空気中で、昇温速度１０℃／分で２４０℃まで昇温し、２４０℃で１時間保持し、雰囲気を窒素に切り替えて１０℃／分で昇温して、到達温度４５０℃・３０秒保持した時点での質量保持率が２０％以上の安定性を有するものを用いることが、耐炎化での微粒子発生を抑えることが出来るので好ましく、５０％以上の安定性を有するものであることがより好ましい。 Silicone oil is pre-dried at 105 ° C for 5 hours, heated to 240 ° C at a heating rate of 10 ° C / min in the air by thermobalance analysis, and kept at 240 ° C for 1 hour to create an atmosphere. Switching to nitrogen, raising the temperature at 10 ° C./min, and using a material having a mass retention rate of 20% or more when held at an ultimate temperature of 450 ° C. for 30 seconds is to generate fine particles in flame resistance Therefore, it is preferable to have a stability of 50% or more.
このようにして得られたポリアクリロニトリル系繊維束を、２００〜３００℃の所定の温度で熱処理することで耐炎化処理を行う。熱処理炉としては、熱風循環式の横型耐炎化炉が好ましく用いられ、かかる横型耐炎化炉の内側もしくは外側の両端には横方向に糸折り返し用のローラーが多段に設置されている。本発明では、かかる熱処理炉を水平に横断した繊維束が、折り返し用のローラーにより進行方向を逆に変えて、耐炎化炉内の横断を繰り返し、熱風を繊維束の流れと垂直方向に循環させて加熱させることで、ポリアクリロニトリル系繊維束が耐炎化処理される。 The polyacrylonitrile fiber bundle thus obtained is subjected to a flameproofing treatment by heat treatment at a predetermined temperature of 200 to 300 ° C. As the heat treatment furnace, a hot air circulation type horizontal flameproofing furnace is preferably used, and rollers for yarn folding are installed in multiple stages in the lateral direction at both ends inside or outside the horizontal flameproofing furnace. In the present invention, a fiber bundle horizontally traversing such a heat treatment furnace is reversed in the direction of travel by a roller for folding, and is repeatedly traversed in a flameproofing furnace to circulate hot air in a direction perpendicular to the flow of the fiber bundle. The polyacrylonitrile fiber bundle is flameproofed by heating.
このとき、耐炎化繊維束の単糸直径は、炭素繊維束を製造したときに十分な引張強度を発現するために、耐炎化繊維束の単糸繊度は０．４〜１．７ｄｔｅｘであることが好ましく、単糸直径は６〜１３μｍとすることがより好ましい。また、耐炎化繊維束の密度は１．３４〜１．４０ｇ／ｃｍ３であることが好ましい。 At this time, the single yarn diameter of the flame-resistant fiber bundle is 0.4 to 1.7 dtex in order to express sufficient tensile strength when the carbon fiber bundle is produced. And the single yarn diameter is more preferably 6 to 13 μm. The density of the flameproof fiber bundle is preferably 1.34 to 1.40 g / cm 3 .
耐炎化のための熱処理炉内では、シリコーン系油剤が加熱・酸化されて生成される粉塵などの微粒子や熱処理炉の周辺外気や装置からの金属元素を含む微粒子や粉塵などの微粒子に加えて、シリコーン系油剤やポリアクリロニトリル系繊維束そのものから発生する、タール成分などに由来する粉塵などの微粒子が、炭素繊維束の連続生産により炉内に溜まり、これが品質低下の原因となる。 In the heat treatment furnace for flame resistance, in addition to fine particles such as dust produced by heating and oxidation of silicone oil, fine particles containing metal elements from the outside air and equipment around the heat treatment furnace and fine particles such as dust, Fine particles such as dust derived from the tar component generated from the silicone-based oil agent or the polyacrylonitrile-based fiber bundle itself accumulate in the furnace due to the continuous production of the carbon fiber bundle, and this causes a deterioration in quality.
熱処理炉を循環する熱風には空気などの酸化性気体が用いられる。酸化性気体に存在する上記粉塵などの微粒子は少ないほうが良いが、かかる微粒子は上記の理由により酸化性気体中に絶えず発生、堆積するため、その濃度をゼロにすることは工業的には困難である。一方、熱処理炉内に供給する外気を取り入れる時に濾過することや、装置に使用する金属部分の材質をステンレスなどのさびにくい材質とすることのほか、シリコーン系油剤の使用量を所望の物性が発現する範囲で低く抑えたり、耐熱性が良好なアミノ変性シリコーンを含有するシリコーン系油剤を使用して耐炎化処理でのシリコーン系油剤の分解を抑制したりすることなどにより、上記微粒子濃度を２５００個／リットル以下に保つことによって、得られる炭素繊維束の引張強度レベルを高い水準に保つことができる。微粒子濃度をできる限り小さくするためには、循環する酸化性気体の大部分を集塵処理することで可能となるが、熱処理炉内で安定した酸化性気体の風量を確保し繊維束の反応を安全に制御するためには、バイパスで一部エアのみ集塵処理することが望ましく、設備ないし運転コストと安全性との兼ね合いを考慮した上で設計すると良い。かかる観点から、熱処理炉内を循環する酸化性気体に含まれる粒径０．３μｍ以上の微粒子の濃度を３００個／リットル以上であると良い。また、粉塵が繊維束に付着するのを防止するためには、かかる粒径０．３μｍ以上の微粒子の濃度を、６００個／リットル以下に保つことが好ましい。本発明は、耐炎化に使用する酸化性気体に含まれる粒径０．３μｍ以上の微粒子の濃度を３００〜２５００個／リットルの範囲、好ましくは３００〜６００個／リットルの範囲とし、かかる範囲で炭素繊維束の連続生産をせんとするものである。 An oxidizing gas such as air is used for the hot air circulating in the heat treatment furnace. It is better to have less fine particles such as dust in the oxidizing gas, but such fine particles are constantly generated and deposited in the oxidizing gas for the above reasons, so it is industrially difficult to make the concentration zero. is there. On the other hand, in addition to filtering the outside air supplied to the heat treatment furnace and making the metal parts used in the equipment less rust-resistant, such as stainless steel, the desired amount of silicone oil is used The fine particle concentration is 2500 by controlling the decomposition of the silicone oil in the flameproofing treatment by using a silicone oil containing an amino-modified silicone with good heat resistance. By keeping below 1 / liter, the tensile strength level of the obtained carbon fiber bundle can be kept at a high level. In order to reduce the concentration of fine particles as much as possible, it is possible to collect most of the circulating oxidizing gas by collecting dust. However, the air flow of the oxidizing gas is secured in the heat treatment furnace, and the reaction of the fiber bundle is ensured. In order to control it safely, it is desirable to collect only part of the air by bypass, and it is better to design in consideration of the balance between equipment or operating cost and safety. From such a viewpoint, the concentration of fine particles having a particle size of 0.3 μm or more contained in the oxidizing gas circulating in the heat treatment furnace is preferably 300 particles / liter or more. In order to prevent dust from adhering to the fiber bundle, it is preferable to keep the concentration of fine particles having a particle size of 0.3 μm or more at 600 particles / liter or less. In the present invention, the concentration of fine particles having a particle size of 0.3 μm or more contained in the oxidizing gas used for flame resistance is in the range of 300 to 2500 / liter, preferably in the range of 300 to 600 / liter. It is intended to continuously produce carbon fiber bundles.
さらに本発明者らは、耐炎化繊維束に付着した粉塵等の微粒子に着目し、耐炎化繊維束に付着している微粒子の個数とその元素成分に関する詳細な分析を行った結果、シリコーン系油剤由来の微粒子だけでなく、外気由来の粉塵やタール固化物由来の粉塵等の微粒子も炭素繊維束の品質低下に寄与していることを明らかにしたのである。より詳細には、高引張強度の炭素繊維束を得るのに好適な耐炎化繊維束、およびその耐炎化繊維束を用いた炭素繊維束の製造に際し、これら微粒子のうち、粒径が０．３μｍ以上のもので特定の金属元素が主成分であれば炭素繊維束の品質に悪影響を及ぼすものであることを見出し、これらの微粒子の付着をも防止することで高引張強度の炭素繊維束を安定して製造できることを見出したのである。 Furthermore, the inventors focused on fine particles such as dust adhering to the flame resistant fiber bundle, and as a result of conducting a detailed analysis on the number of fine particles adhering to the flame resistant fiber bundle and their elemental components, It was clarified that not only the fine particles derived from the particles but also fine particles such as dust derived from the outside air and dust derived from the tar solidified product contributed to the deterioration of the quality of the carbon fiber bundle. More specifically, in the production of a flame-resistant fiber bundle suitable for obtaining a carbon fiber bundle having a high tensile strength, and a carbon fiber bundle using the flame-resistant fiber bundle, among these fine particles, the particle diameter is 0.3 μm. As described above, if a specific metal element is a main component, it has been found that the quality of the carbon fiber bundle is adversely affected, and by preventing the adhesion of these fine particles, a high tensile strength carbon fiber bundle can be stabilized. And found that it can be manufactured.
また、耐炎化繊維束には、微粒子が付着していない場所に傷が形成されていることが観察されることがあるが、これは、微粒子が耐炎化繊維束に付着し、それが原因で耐炎化繊維束の単糸に傷を生じさせた後に微粒子が脱落したものと考えられ、耐炎化繊維束に付着している微粒子と同様の炭素繊維束の引張強度の低下をもたらしていると推定される。 In addition, in the flame-resistant fiber bundle, it may be observed that scratches are formed in a place where the fine particles are not attached. This is because the fine particles are attached to the flame-resistant fiber bundle. Presumed that the fine particles dropped off after causing damage to the single yarn of the flame-resistant fiber bundle, resulting in a decrease in the tensile strength of the carbon fiber bundle similar to the fine particles adhering to the flame-resistant fiber bundle. Is done.
このような検討結果から、本発明では、熱処理炉内の微粒子濃度Ｄ（個／リットル）、被処理物である繊維束の幅をＷ（ｃｍ／ストランド）、熱処理炉内の繊維束を循環熱風が通過する風速をＶ（ｍ／ｓ）、繊維束が熱処理炉内を通過する総長さをＬ（ｍ）、繊維束が熱処理炉内を通過する速度をＳ（ｍ／ｓ）とするとき、
［Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］ (式１)
が５〜４０である条件で加熱（耐炎化）処理する必要がある。
From these examination results, in the present invention, the fine particle concentration D (number / liter) in the heat treatment furnace, the width of the fiber bundle as the object to be treated is W (cm / strand), and the fiber bundle in the heat treatment furnace is circulated with hot air. Is V (m / s), the total length of the fiber bundle passing through the heat treatment furnace is L (m), and the speed of the fiber bundle passing through the heat treatment furnace is S (m / s).
[D × (W × V × L)] / [(S / 60) × 10 5 ] (Formula 1)
It is necessary to perform the heating (flame resistance) treatment under the condition of 5 to 40.
ここで、（式１）における各記号は以下のとおりに定義される。
Ｄ：前記熱処理炉内に存在する粒径０．３μｍ以上の微粒子の濃度［個／リットル］であり、熱処理炉内でサンプリングした値である。
Ｗ：繊維束の幅［ｃｍ／ストランド］であり、具体的には、被処理糸条の断面を楕円形状に近似し、該糸条を耐炎化時の張力と同じ張力で平板上に静置したときの糸幅を楕円の長径で表した値であって、熱処理炉中で直交する加熱媒体流に接触する繊維束の幅方向の距離である。
Ｖ：繊維束を通過する循環熱風の風速［ｍ／秒］であり、供給される熱風の風量を熱処理炉の風向と垂直の断面積で除した値である。
Ｌ：繊維束が通過する熱処理炉の炉長[ｍ]であり、熱処理炉全体にある繊維束の総長さである。
Ｓ：繊維束の熱処理炉内の通過速度［ｍ／分］であり、炉内通過の入速度と出速度の平均値である。
Here, each symbol in (Formula 1) is defined as follows.
D: Concentration [particles / liter] of fine particles having a particle size of 0.3 μm or more existing in the heat treatment furnace, which is a value sampled in the heat treatment furnace.
W: width of the fiber bundle [cm / strand], specifically, the cross section of the yarn to be treated is approximated to an elliptical shape, and the yarn is left on a flat plate with the same tension as that at the time of flame resistance. The width of the fiber bundle is a value expressed by the major axis of the ellipse, and is the distance in the width direction of the fiber bundle contacting the orthogonal heating medium flow in the heat treatment furnace.
V: Wind speed [m / sec] of the circulating hot air passing through the fiber bundle, which is a value obtained by dividing the air volume of the supplied hot air by the cross-sectional area perpendicular to the wind direction of the heat treatment furnace.
L: Furnace length [m] of the heat treatment furnace through which the fiber bundle passes, and is the total length of the fiber bundle in the entire heat treatment furnace.
S: The passing speed of the fiber bundle in the heat treatment furnace [m / min], which is an average value of the entrance speed and the exit speed of passing through the furnace.
なお、熱処理炉が２炉以上に分割されている場合、おのおのの炉で式（１）を計算して,それらの和をとった値が５〜４０である必要がある。 In addition, when the heat processing furnace is divided | segmented into 2 or more furnaces, it is necessary to calculate Formula (1) with each furnace, and the value which took those sums should be 5-40.
（式１）の値を４０以下にすることで、耐炎化繊維束が熱処理炉内で粉塵等の微粒子に曝される量が少なくなることから、耐炎化繊維束に付着する粉塵等の微粒子の個数や、耐炎化繊維束の単糸表面の傷の個数が減少し、高いレベルで引張強度が安定する炭素繊維束を長期間連続的に生産することが可能となる耐炎化繊維束を得ることができる。 By setting the value of (Equation 1) to 40 or less, the amount of the flame-resistant fiber bundle exposed to fine particles such as dust in the heat treatment furnace is reduced. To obtain a flame-resistant fiber bundle that can continuously produce a carbon fiber bundle having a high tensile strength and a stable level at a high level for a long period of time. Can do.
一方、（式１）の値を５以上にすることで、熱処理炉内の熱風風速Ｖが小さくなりすぎたり、繊維束の糸幅が小さくなりすぎたりして反応熱の除熱作用が失われ、繊維束の温度が無秩序に上昇することによる物性低下、また甚だしい場合の温度が高くなりすぎることによる糸切れを防ぐことができる。また、繊維束の通過速度が大きすぎる場合には、熱処理炉中の繊維束の滞留時間が小さくなるため、耐炎化に必要な熱量供給を確保するために耐炎化温度を高く設定することになる。（式１）の値を５以上にすることで、このような理由による耐炎化繊維束やそれを焼成して得られる炭素繊維束の物性低下や、糸切れ発生を防ぐことができる。（式１）の値はより好ましくは５〜３５である。 On the other hand, by setting the value of (Equation 1) to 5 or more, the hot air wind velocity V in the heat treatment furnace becomes too small, the yarn width of the fiber bundle becomes too small, and the heat removal action of the reaction heat is lost. Further, it is possible to prevent the physical properties from being lowered due to the fiber bundle temperature rising randomly, and the yarn breakage due to excessively high temperature. In addition, when the passing speed of the fiber bundle is too high, the residence time of the fiber bundle in the heat treatment furnace is reduced, so that the flameproofing temperature is set high in order to ensure the supply of heat necessary for flameproofing. . By setting the value of (Equation 1) to 5 or more, it is possible to prevent deterioration of physical properties of the flame-resistant fiber bundle and the carbon fiber bundle obtained by firing the fiber bundle and the occurrence of yarn breakage. The value of (Formula 1) is more preferably 5 to 35.
本発明では、（式１）の値を５〜４０に制御する方法としては、下記する方法で測定された粒径０．３μｍ以上の微粒子の濃度を３００〜２５００個／リットルとした循環熱風を用いて耐炎化を実施するに際して、繊維束の糸幅、繊維束の炉内通過速度、繊維束の炉内の滞留時間を制御して、上記の値の範囲とすることによって達成できる。具体的には、繊維束の糸幅は、原料として用いられるポリアクリロニトリル系繊維束の、フィラメント数、算術平均表面粗さＲａであらわされる単糸表面の平滑度、集束性、耐炎化における、櫛ガイドの形状や、溝付きローラーの形状、張力、糸速、熱処理炉の炉長などを設定することで達成される。好ましい耐炎化繊維束を構成する単糸の算術平均表面粗さＲａは１〜２０ｎｍであって、上記のとおりに定義される繊維束の好ましい糸幅は０．５〜１．０ｃｍ／ストランドである。この糸幅を基礎として、炉長、糸速、滞留時間を決定して（式１）の値を所望の値に設定することができる。好ましい繊維束の炉内通過速度は３〜１５ｍ／分、好ましい炉内の滞留時間は２５〜１２０分、より好ましくは４０〜８０分である。 In the present invention, as a method of controlling the value of (Equation 1) to 5 to 40, circulating hot air with the concentration of fine particles having a particle size of 0.3 μm or more measured by the following method being 300 to 2500 particles / liter is used. When the flame resistance is implemented by using the fiber bundle, it can be achieved by controlling the yarn width of the fiber bundle, the passing speed of the fiber bundle in the furnace, and the residence time of the fiber bundle in the furnace so as to be within the above range. Specifically, the yarn width of the fiber bundle is defined as the number of filaments of the polyacrylonitrile fiber bundle used as a raw material, the smoothness of the surface of the single yarn expressed by the arithmetic average surface roughness Ra, the convergence, and the flame resistance. This is achieved by setting the shape of the guide, the shape of the grooved roller, tension, yarn speed, furnace length of the heat treatment furnace, and the like. The arithmetic average surface roughness Ra of the single yarn constituting the preferred flame-resistant fiber bundle is 1 to 20 nm, and the preferred yarn width of the fiber bundle defined as described above is 0.5 to 1.0 cm / strand. . Based on this yarn width, the furnace length, yarn speed, and dwell time can be determined to set the value of (Equation 1) to a desired value. The preferable passing speed of the fiber bundle in the furnace is 3 to 15 m / min, and the preferable residence time in the furnace is 25 to 120 minutes, more preferably 40 to 80 minutes.
このようにして得られる耐炎化繊維束は、その単糸表面を観察したときに、Ｓｉ、Ｃ、Ｎａ、Ｍｇ、Ａｌ、Ｋ、Ｃａ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｚｎのいずれかを主成分とする微粒子の個数と、下記する０．３μｍ以上の単糸表面の傷の個数の合計が観察面積０．１ｍｍ２あたり１５個以下であって、品質が良好な炭素繊維束を得ることができる。これ以外の元素については、その個数が少ないことが望ましいが、炭素繊維束の品質低下にはほとんど影響を及ぼさないので、本発明ではその個数は問わない。 The flame-resistant fiber bundle thus obtained is mainly composed of one of Si, C, Na, Mg, Al, K, Ca, Mn, Fe, Co, Ni, and Zn when the surface of the single yarn is observed. A total of the number of fine particles as a component and the number of scratches on the surface of a single yarn of 0.3 μm or more described below is 15 or less per observation area of 0.1 mm 2, and a carbon fiber bundle having good quality can be obtained. it can. Regarding the other elements, it is desirable that the number thereof is small, but the number of elements does not matter in the present invention because it hardly affects the quality deterioration of the carbon fiber bundle.
ここで、耐炎化繊維束の単糸に付着した微粒子と傷の個数及び微粒子の元素成分分析は、下記方法で測定したものである。 Here, the number of fine particles and scratches attached to the single yarn of the flame-resistant fiber bundle, and the elemental component analysis of the fine particles were measured by the following methods.
耐炎化繊維束を、走査型電子顕微鏡を用い３０００倍の倍率で単糸表面を観察し（１視野は４２μｍ×３２μｍ）、粒径０．３μｍ以上の粒子の個数と、０．３μｍ以上の傷の個数をカウントし、０．１ｍｍ２あたりの数値を測定する。ここで粒子の粒径とは、粒子を楕円形と近似したときの短径の長さであらわし、傷の大きさも傷を楕円状に近似したときの短径の長さで現す。次に０．３μｍ以上の粒子について、エネルギー分散型Ｘ線分析装置を用いてその元素成分を分析する。なお、１つの粒子が複数の元素から成る場合は、その原子個数濃度が最も高い元素をその主成分とし、Ｓｉ、Ｃ、Ｎａ、Ｍｇ、Ａｌ、Ｋ、Ｃａ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｚｎが主成分であれば微粒子１個とカウントする。 Using a scanning electron microscope, observe the surface of the single yarn at a magnification of 3000 times (one field is 42 μm × 32 μm), the number of particles having a particle size of 0.3 μm or more, and scratches of 0.3 μm or more Are counted and a numerical value per 0.1 mm 2 is measured. Here, the particle diameter of the particle is the length of the short diameter when the particle is approximated to an ellipse, and the size of the scratch is also expressed as the length of the short diameter when the scratch is approximated to an ellipse. Next, about the particle | grains more than 0.3 micrometer, the elemental component is analyzed using an energy dispersive X-ray analyzer. When one particle is composed of a plurality of elements, the element having the highest atomic number concentration is the main component, and Si, C, Na, Mg, Al, K, Ca, Mn, Fe, Co, Ni, If Zn is the main component, it is counted as one fine particle.
このとき、耐炎化繊維束に付着している微粒子は、直接機械的な作用によって耐炎化繊維束が炭化処理されるときに欠陥を生じる可能性があるだけでなく、上記元素が炭素繊維束の製造過程で耐炎化繊維束を構成する元素と反応して欠陥を生じる可能性があり、また、耐炎化で生じた傷については,それ自体が欠陥であるだけでなく、炭素化の過程で欠陥が成長する可能性があるので、微粒子の個数と傷の個数が炭素繊維束の引張強度に与える影響が大きい。 At this time, the fine particles adhering to the flame-resistant fiber bundle may not only cause a defect when the flame-resistant fiber bundle is carbonized by a direct mechanical action, but the above-mentioned elements may be included in the carbon fiber bundle. It may react with the elements that make up the flame-resistant fiber bundle during the production process, and may cause defects, and scratches caused by flame resistance are not only defects themselves, but also defects during the carbonization process. Therefore, the influence of the number of fine particles and the number of scratches on the tensile strength of the carbon fiber bundle is large.
本発明では、（式１）の値を５〜４０に制御することで、耐炎化繊維束が粉塵等の微粒子に曝される機会を問題ない程度に減少させることができる。よって、耐炎化繊維束に付着する微粒子の個数と傷の個数を観察面積０．１ｍｍ２あたり１５個以下に減少させることができ、品質の低下や糸切れ等を起こさず、高いレベルで引張強度が安定する炭素繊維束を長期間連続的に生産することが可能となる。 In the present invention, by controlling the value of (Equation 1) to 5 to 40, it is possible to reduce the chance that the flame-resistant fiber bundle is exposed to fine particles such as dust to the extent that there is no problem. Therefore, the number of fine particles adhering to the flame-resistant fiber bundle and the number of scratches can be reduced to 15 or less per observation area of 0.1 mm 2 , and the tensile strength at a high level without causing quality deterioration or yarn breakage. It is possible to continuously produce a carbon fiber bundle that is stable for a long period of time.
このようにして得られた耐炎化繊維束を、窒素などの不活性雰囲気下で、最高温度を１２００℃以上で焼成し炭素化することによって、耐炎化炉を清掃せずに連続生産する全期間において炭素繊維束の引張強度が４．７ＧＰａ以上、引張弾性率が２００ＧＰａ以上で、引張強度の経時変化の小さい炭素繊維束を製造することができる。 ここで、耐炎化炉を清掃せずに連続生産する全期間というのは、以下のとおりに定義される。すなわち、通常炭素繊維束の製造工程では、アクリル系繊維束が一定の長さに巻かれたパッケージの状態であるか、一定の長さがキャンなどに収納された状態で供給し、一定量が処理されると、一旦設備を停止するか、あるいは停止せずに糸端をつないで、炭素繊維束が連続生産される。そして、品種等の条件によって異なるが、０．５ヶ月〜１年生産を行い、設備を停止して清掃を行ってから，再度生産を開始する。上記の清掃と清掃の間に生産する期間のことを、耐炎化炉を清掃せずに連続生産する全期間とする。すなわち、本発明において、アクリル系繊維束のパッケージまたはキャンの切り替え時間は、清掃を実施しない場合は連続生産期間に含めることとする。 The entire period of continuous production without cleaning the flameproofing furnace by firing and carbonizing the flameproofed fiber bundle obtained in this way under an inert atmosphere such as nitrogen at a maximum temperature of 1200 ° C or higher. Thus, a carbon fiber bundle having a tensile strength of 4.7 GPa or more and a tensile modulus of 200 GPa or more and a small change in tensile strength with time can be produced. Here, the total period of continuous production without cleaning the flameproofing furnace is defined as follows. That is, in the normal carbon fiber bundle manufacturing process, the acrylic fiber bundle is supplied in a package state in which the acrylic fiber bundle is wound to a certain length, or a certain length is stored in a can etc. Once processed, the carbon fiber bundle is continuously produced by stopping the equipment once or connecting the yarn ends without stopping. And although it changes with conditions, such as a kind | species, after 0.5 month-1 year production is performed, after stopping an equipment and cleaning, production is started again. The period of production between the above cleanings is the entire period of continuous production without cleaning the flameproofing furnace. That is, in the present invention, the switching time of the acrylic fiber bundle package or can is included in the continuous production period when cleaning is not performed.
また、上記耐炎化繊維束であって、単糸繊度が１．０ｄｔｅｘ以下の耐炎化繊維束を焼成の最高温度を１３００℃以上とし、生産開始直後、並びに連続生産後の炭素繊維束の引張強度が５．５ＧＰａ以上、引張弾性率２８０ＧＰａ以上の炭素繊維束とすることもより好ましい。さらに耐炎化繊維束の単糸の算術平均表面粗さＲａを２０ｎｍ以下、さらに好ましくは１５ｎｍ以下とすることで、炭素繊維束の引張強度、引張弾性率をさらに向上させることができ、好ましい。 In addition, the flame-resistant fiber bundle having the single fiber fineness of 1.0 dtex or less is fired at a maximum temperature of 1300 ° C. or higher, and the tensile strength of the carbon fiber bundle immediately after the start of production and after continuous production. Is more preferably a carbon fiber bundle having a tensile modulus of 280 GPa or more and 5.5 GPa or more. Furthermore, by setting the arithmetic average surface roughness Ra of the single yarn of the flame-resistant fiber bundle to 20 nm or less, more preferably 15 nm or less, the tensile strength and tensile elastic modulus of the carbon fiber bundle can be further improved, which is preferable.
これらの炭素繊維束は、さらに、マトリックスとの接着性を向上するため、電解処理を行うことも好ましく、得られる炭素繊維束に集束性を付与するため、サイジング処理をして、サイジング剤を付与することもさらに好ましい。 These carbon fiber bundles are also preferably subjected to electrolytic treatment in order to improve adhesion to the matrix, and sizing treatment is applied to the resulting carbon fiber bundle in order to impart convergence. It is further preferable to do this.
このようにして得られる耐炎化繊維束は、炭素繊維束に転換（焼成）した際のストランド強度に代表される引張強度など品質の経時変化が小さい、安定的な長期間の連続生産が可能となる。 The flame-resistant fiber bundle obtained in this way is capable of stable and long-term continuous production with little change over time in quality such as tensile strength typified by strand strength when converted (fired) into a carbon fiber bundle. Become.
以下に本発明を実施例および比較例によりさらに具体的に説明する。なお、各特性の評価方法・測定方法は下記に記載の方法によった。 Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In addition, the evaluation method and the measuring method of each characteristic were based on the method as described below.
＜耐炎化繊維束に付着した微粒子と傷の個数及び微粒子の元素成分分析＞
耐炎化繊維束を約３ｃｍの長さに切り出し、カーボンテープを用いて動かないように電子顕微鏡用サンプル台に固定した。この際、糸条は薄く均一に拡げ、サンプル台が観察されないように、また、なるべく単糸の重なりがないように固定した。イオンスパッタ（例えば、日立ハイテクノロジーズ社製Ｅ−１０３０）を用いて白金パラジウム合金により３０秒間蒸着を行った後、走査型電子顕微鏡（ＳＥＭ；例えば、日立ハイテクノロジーズ社製Ｓ４８００）で加速電圧５．０ｋＶ、３０００倍の倍率で単糸表面を観察し（１視野は４２μｍ×３２μｍ）、粒径０．３μｍ以上の微粒子の個数と、０．３μｍ以上の傷の個数をカウントした。ここで粒子の粒径とは、粒子を楕円形と近似したときの短径の長さであらわし、傷の大きさも傷を楕円状に近似したときの短径の長さで現した。それぞれの粒子について、エネルギー分散型Ｘ線分析装置（ＥＤＸ；例えば、堀場製作所製 ＥＭＡＸ Ｓｕｐｅｒ Ｘｅｒｏｐｈｙ）を用いてその元素成分を分析した。なお、１つの粒子が複数の元素から成る場合は、その原子個数濃度が最も高い元素をその主成分とし、Ｓｉ、Ｃ、Ｎａ、Ｍｇ、Ａｌ、Ｋ、Ｃａ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｚｎが主成分であれば粉塵１個とカウントした。
<Analysis of the number of fine particles and scratches adhering to the flame-resistant fiber bundle and elemental component of fine particles>
The flame-resistant fiber bundle was cut into a length of about 3 cm and fixed to a sample stage for an electron microscope so as not to move using a carbon tape. At this time, the yarn was spread thinly and uniformly, and was fixed so that the sample stage was not observed and the single yarns were not overlapped as much as possible. After performing deposition for 30 seconds with a platinum-palladium alloy using ion sputtering (for example, E-1030 manufactured by Hitachi High-Technologies Corporation), an accelerating voltage of 5.5 using a scanning electron microscope (SEM; for example, S4800 manufactured by Hitachi High-Technologies Corporation). The surface of the single yarn was observed at a magnification of 0 kV and 3000 times (one visual field is 42 μm × 32 μm), and the number of fine particles having a particle size of 0.3 μm or more and the number of scratches having a size of 0.3 μm or more were counted. Here, the particle diameter of the particle is the length of the short diameter when the particle is approximated to an ellipse, and the size of the scratch is also expressed as the length of the short diameter when the scratch is approximated to an ellipse. About each particle | grain, the element component was analyzed using the energy dispersive X-ray-analysis apparatus (EDX; For example, Horiba Seisakusho EMAX Super Xerophy). When one particle is composed of a plurality of elements, the element having the highest atomic number concentration is the main component, and Si, C, Na, Mg, Al, K, Ca, Mn, Fe, Co, Ni, If Zn was the main component, it was counted as one dust.
以上の観察を観察点数１０００点にわたり繰り返し行い、観察された粉塵の個数を観察総面積で割り、０．１ｍｍ２あたりの微粒子個数に換算した。 The above observation was repeated over 1000 observation points, and the number of observed dust was divided by the total observation area and converted into the number of fine particles per 0.1 mm 2 .
＜ストランド引張強度、引張弾性率＞
ＪＩＳ Ｒ ７６０１（１９８６）の「樹脂含浸ストランド試験法」に従い測定した。
<Strand tensile strength, tensile modulus>
It was measured according to “Resin-impregnated strand test method” of JIS R 7601 (1986).
＜微粒子濃度の測定＞
微粒子濃度Ｄは、光散乱式パーティクルカウンタ（例えば、ＲＩＯＮ社 ＫＣ−０１Ｅ）を用いて測定した。すなわち、試料空気流量０．５リットル／分で３４秒の間エアを吸引し、０．１立方フィート（０．２８３リットル）に含まれる０．３以上０．５μｍ未満、０．５以上１．０μｍ未満、１．０以上２．０μｍ未満、２．０以上５．０μｍ未満、５．０μｍ以上の５段階粒子数を同時に計測し、その値をそれぞれＤ０．３、Ｄ０．５、Ｄ１．０、Ｄ２．０、Ｄ５．０（個／０．２８３リットル）とするとき、以下の換算式によって各粒子の濃度を５．０μｍの粒子数に換算した値を使用した。５．０μｍの粒子数への換算式＝［｛Ｄ０．３／（５／０．３）｝＋｛Ｄ０．５／（５／０．５）｝＋｛Ｄ１．０／（５／１．０）｝＋｛Ｄ２．０／（５／２．０）｝＋Ｄ５．０］／０．２８３（個／リットル）
＜算術平均表面粗さの測定＞
単糸の算術平均表面粗さ（Ｒａ）は次のようにして測定した。測定試料は、長さ数ｍｍ 程度にカットした耐炎化繊維束を使用した。銀ペーストを用いて基板（シリコーンウエハ）上に固定し、原子間力顕微鏡（ＡＦＭ）によって各単糸の中央部において、３次元表面形状の像を得た。原子間力顕微鏡としてはＤｉｇｉｔａｌ Ｉｎｓｔｕｍｅｎｔｓ社製 ＮａｎｏＳｃｏｐｅＩＩＩａにおいてＤｉｍｅｎｓｉｏｎ３０００ステージシステムを使用した。観測条件は下記条件とした。
・走査モード： タッピングモード
・探針： シリコーンカンチレバー
・走査範囲： ０．６ μｍ×０．６μｍ
・走査速度： ０．３Ｈｚ
・ピクセル数： ５１２×５１２
・測定環境： 室温、大気中
各試料について、単糸１本から１箇所ずつ観察して得られた像について、繊維断面の丸みを３次曲面で近似し、得られた像全体を対象として、算術平均表面粗さ（Ｒａ）を算出した。単糸５本について、算術平均表面粗さ（Ｒａ）を求め平均した。
<Measurement of fine particle concentration>
The fine particle concentration D was measured using a light scattering particle counter (for example, RION KC-01E). That is, air is sucked for 34 seconds at a sample air flow rate of 0.5 liter / minute, and is contained in 0.1 cubic foot (0.283 liters) of 0.3 to less than 0.5 μm, 0.5 to 1. The number of five-stage particles of less than 0 μm, 1.0 or more and less than 2.0 μm, 2.0 or more and less than 5.0 μm, or 5.0 μm or more is simultaneously measured, and the values are D 0.3 , D 0.5 , When 1.0 , D 2.0 and D 5.0 (pieces / 0.283 liters), values obtained by converting the concentration of each particle into the number of particles of 5.0 μm by the following conversion formula were used. Conversion formula to the number of particles of 5.0 μm = [{D 0.3 /(5/0.3)}+{D 0.5 /(5/0.5)}+{D 1.0 / (5 /1.0)}+{D 2.0 /(5/2.0)}+D 5.0 ] /0.283 (pieces / liter)
<Measurement of arithmetic average surface roughness>
The arithmetic average surface roughness (Ra) of the single yarn was measured as follows. As a measurement sample, a flame-resistant fiber bundle cut to a length of several millimeters was used. It fixed on the board | substrate (silicone wafer) using the silver paste, and the image of the three-dimensional surface shape was obtained in the center part of each single yarn with the atomic force microscope (AFM). As an atomic force microscope, a Dimension 3000 stage system was used in NanoScope IIIa manufactured by Digital Instruments. The observation conditions were as follows.
・ Scanning mode: Tapping mode ・ Probe: Silicone cantilever ・ Scanning range: 0.6 μm × 0.6 μm
・ Scanning speed: 0.3Hz
-Number of pixels: 512 x 512
・ Measurement environment: At room temperature and in the air For each sample, for each image obtained by observing one single yarn at a location, the roundness of the fiber cross section is approximated by a cubic surface, and the entire image obtained is targeted. Arithmetic mean surface roughness (Ra) was calculated. The arithmetic average surface roughness (Ra) was obtained and averaged for five single yarns.
＜シリコーン系油剤の耐熱性測定＞
油剤乳化物、あるいは自己乳化性の場合は油剤溶液約１ｇを１０５℃で５時間乾燥し、試料１５〜２０ｍｇを熱天秤装置（ＴＧ−ＤＴＡ）装置にて、下記温度プロフィルで処理した。
<Measurement of heat resistance of silicone oil>
In the case of oil emulsion or self-emulsification, about 1 g of oil solution was dried at 105 ° C. for 5 hours, and 15 to 20 mg of a sample was treated with a thermobalance device (TG-DTA) device with the following temperature profile.
空気中で常温から２４０℃まで、昇温速度１０℃／分、その後２４０℃で１時間保持し、加熱媒体を窒素に切り替えた後１０℃／分で昇温し、４５０℃で３０秒保持したときの、常温からの質量保持率を耐熱性の指標とした。加熱媒体の流量は３０リットル／分である。これらは、耐炎化と炭化前半の熱履歴をモデル化したものである。 From room temperature to 240 ° C. in air, the rate of temperature increase was 10 ° C./min, then held at 240 ° C. for 1 hour, the heating medium was switched to nitrogen, the temperature was increased at 10 ° C./min, and held at 450 ° C. for 30 seconds. The mass retention from normal temperature was used as an index of heat resistance. The flow rate of the heating medium is 30 liters / minute. These models the flame history and the thermal history of the first half of carbonization.
（実施例１〜６、比較例１〜３）
アクリロニトリル９９．５モル％とイタコン酸０．５モル％が共重合してなる共重合体を、ジメチルスルホキシドを溶媒とする溶液重合法により製造し、アクリル系共重合体の含有率が２２質量％である紡糸原液を得た。この紡糸原液を、４０ ℃で、孔数４，０００の紡糸口金を用いて一旦空気中に吐出し、約４ｍｍの空間を通過させた後、１０℃にコントロールした３５％ ジメチルスルホキシドの水溶液からなる凝固浴に導入する乾湿式紡糸法により凝固させた。この際の計算ドラフトは１．３に設定した。得られた凝固糸を、水洗、延伸、油剤付与した後、乾燥させ、スチーム延伸することで、製糸全延伸倍率を１５倍とし、単糸繊度１．１ｄｔｅｘ、単糸本数１２，０００本のポリアクリロニトリル系繊維束を得た。
(Examples 1-6, Comparative Examples 1-3)
A copolymer obtained by copolymerizing 99.5 mol% of acrylonitrile and 0.5 mol% of itaconic acid was produced by a solution polymerization method using dimethyl sulfoxide as a solvent, and the content of the acrylic copolymer was 22% by mass. A spinning dope was obtained. This spinning stock solution is composed of an aqueous solution of 35% dimethyl sulfoxide controlled at 10 ° C. after being discharged into the air once at 40 ° C. using a spinneret having a hole number of 4,000 and passing through a space of about 4 mm. It was coagulated by the dry and wet spinning method introduced into the coagulation bath. The calculation draft at this time was set to 1.3. The obtained coagulated yarn was washed with water, drawn and oiled, dried, and then steam-drawn, so that the total draw ratio for yarn production was 15 times, the single yarn fineness was 1.1 dtex, and the number of single yarns was 12,000. An acrylonitrile fiber bundle was obtained.
用いた油剤は、アミノ変性されたジメチルシロキサン油剤成分を、ノニオン系界面活性剤を用いて、水分散系としたものと、ジメチルポリシロキサンをポリエチレングリコールで変性して水溶性にした油剤を純分で等量混合したものを用い、その耐熱性は５３％であった。 The used oil agent is a pure component of an amino-modified dimethylsiloxane oil agent component made into a water dispersion using a nonionic surfactant and an oil agent made by modifying dimethylpolysiloxane with polyethylene glycol to make it water-soluble. The equivalent heat resistance was 53%.
次いで、炉内温度２２０〜２７０℃の横型熱風循環式の耐炎化炉において、表１に示す条件で耐炎化処理を行い、連続生産を行った後、不活性化ガス雰囲気下熱処理して得られた炭素繊維束のストランド特性を測定した。また、耐炎化繊維束の単糸表面に付着した粉塵と傷の個数を電子顕微鏡で測定した。結果を表１に示す。このとき耐炎化繊維束の単糸の算術平均表面粗さ（Ｒａ）を測定すると、５．０ｎｍであった。得られた耐炎化繊維束を最高炭化温度１３５０℃で炭化し、電解表面処理後サイジングを施して、炭素繊維束を製造した。 Next, in a horizontal hot air circulation type flameproof furnace having a furnace temperature of 220 to 270 ° C., flameproofing treatment is performed under the conditions shown in Table 1, continuous production is performed, and then heat treatment is performed in an inert gas atmosphere. The strand properties of the carbon fiber bundles were measured. Further, the number of dust and scratches attached to the surface of the single yarn of the flame resistant fiber bundle was measured with an electron microscope. The results are shown in Table 1. At this time, the arithmetic average surface roughness (Ra) of the single yarn of the flame-resistant fiber bundle was measured and found to be 5.0 nm. The obtained flame-resistant fiber bundle was carbonized at a maximum carbonization temperature of 1350 ° C., and subjected to sizing after electrolytic surface treatment to produce a carbon fiber bundle.
実施例１、２については、［Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］が５〜４０の値を満たし、連続生産後もなお炭素繊維束の引張強度は高く、引き続き生産が継続できる状態であった。また、耐炎化繊維束に付着した粉塵と傷の個数も１５個以下であり、良好であった。 In Examples 1 and 2, [D × (W × V × L)] / [(S / 60) × 10 5 ] satisfies the value of 5 to 40, and the tensile strength of the carbon fiber bundle is still after continuous production. It was expensive and production was able to continue. Also, the number of dust and scratches attached to the flameproof fiber bundle was 15 or less, which was good.
実施例３、４については、バグフィルタによって耐炎化炉内の粉塵を集塵し微粒子濃度Ｄを下げることで、［Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］の値は、５〜４０の範囲内で、比較例１、２対比大幅に小さくなり、連続生産後の炭素繊維束の引張強度はさらに高く、さらに生産が継続できる良好な状態であった。 In Examples 3 and 4, the dust in the flameproofing furnace is collected by the bag filter and the fine particle concentration D is lowered, so that [D × (W × V × L)] / [(S / 60) × 10 5 ] Within a range of 5 to 40, the carbon fiber bundle after continuous production was much higher in tensile strength than in Comparative Examples 1 and 2, and was in a good state where production could be continued.
実施例５については、炉内を通過させる糸道を変更し炉内を通過する炉長を２５０ｍとしたところ、［Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］の値は５〜４０を満たし、連続生産後もなお炭素繊維束の引張強度は高く、引き続き生産が継続できる状態であった。 For Example 5, when the yarn path passing through the furnace was changed and the furnace length passing through the furnace was 250 m, [D × (W × V × L)] / [(S / 60) × 10 5 ] Of 5 to 40 was satisfied, the tensile strength of the carbon fiber bundle was still high after continuous production, and production was continued.
実施例６については、糸速を上げることで［Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］の値を５〜４０となるようにした。糸速が上がると耐炎化炉内滞留時間が短くなり、耐炎化反応が不十分となるおそれがあるため、循環熱風の温度を上げ、十分な耐炎化反応が進行するよう留意し実施した。結果、連続性産後の炭素繊維束の引張強度は５．１ＧＰａと良好であった。 For Example 6, the value of [D × (W × V × L)] / [(S / 60) × 10 5 ] was set to 5 to 40 by increasing the yarn speed. When the yarn speed is increased, the residence time in the flameproofing furnace is shortened, and the flameproofing reaction may become insufficient. Therefore, the temperature of the circulating hot air was raised, and sufficient flameproofing reaction proceeded. As a result, the tensile strength of the carbon fiber bundle after continuous production was good at 5.1 GPa.
比較例１、２はいずれも［Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］の値が４０を超えた条件での生産であったが、耐炎化繊維束に付着していた粉塵と傷の個数は４６から４９個と多く、実施例と同期間連続生産した後の炭素繊維束の引張強度は低かったため、生産を停止して炉内清掃をする必要がある状態であった。 Comparative Examples 1 and 2 were all produced under conditions where the value of [D × (W × V × L)] / [(S / 60) × 10 5 ] exceeded 40. The number of dust and scratches adhering to the steel was 46 to 49, and the tensile strength of the carbon fiber bundle after continuous production during the same period as the Example was low, so it was necessary to stop the production and clean the inside of the furnace It was in a certain state.
これらの例における炭素繊維束の引張弾性率は２３０〜２３５ＧＰａの範囲であった。 The tensile elastic modulus of the carbon fiber bundle in these examples was in the range of 230 to 235 GPa.
また、比較例３では、［Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］の値が５未満となるよう、炉内風速を下げることで粒子の付着・傷の発生をさらに防止しようとしたが、糸の除熱が不十分で炉内温度が上昇し、糸切れが多発したため、テストを中止した。 Further, in Comparative Example 3, particle adhesion / scratch is caused by lowering the furnace wind speed so that the value of [D × (W × V × L)] / [(S / 60) × 10 5 ] is less than 5 . However, the test was stopped because the heat removal of the yarn was insufficient and the temperature in the furnace rose, resulting in frequent yarn breakage.
（実施例７、８、比較例４）
以下に記載した以外は実施例１と同様の方法で、油剤をアミノ変性シリコーンとエポキシ変性シリコーンの混合シリコーン分散系の等量混合物を用いて、単糸繊度０．７ｄｔｅｘ、単糸本数２４，０００本のポリアクリロニトリル系繊維束を得たのち、耐炎化反応や炭素繊維束の評価を上記と同様の方法で行った。この混合油剤の耐熱性は、８３％であった。このとき耐炎化繊維束の単糸の算術平均表面粗さ（Ｒａ）を測定すると、６．０ｎｍであった。
(Examples 7 and 8, Comparative Example 4)
Except as described below, a single yarn fineness of 0.7 dtex and a single yarn number of 24,000 were obtained in the same manner as in Example 1, except that the oil agent was an equivalent mixture of a mixed silicone dispersion of amino-modified silicone and epoxy-modified silicone. After obtaining the polyacrylonitrile fiber bundle, the flameproofing reaction and the evaluation of the carbon fiber bundle were performed in the same manner as described above. The mixed oil agent had a heat resistance of 83%. At this time, the arithmetic average surface roughness (Ra) of the single yarn of the flame resistant fiber bundle was measured and found to be 6.0 nm.
実施例７では、［Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］の値を５以上４０以下になるような条件に調整して耐炎化繊維束を作製した。 In Example 7, a flameproof fiber bundle was prepared by adjusting the value of [D × (W × V × L)] / [(S / 60) × 10 5 ] to 5 or more and 40 or less. .
これらの耐炎化繊維束を最高温度１４２０℃で炭化後、電解表面処理、サイジング処理して炭素繊維束を製造した。実施例７では、生産開始直後の炭素繊維束の引張強度は６．４ＧＰａ、連続生産後の炭素繊維束の引張強度は５．７ＧＰａであり、引張強度の低下は０．７ＧＰａと良好であり、引き続き生産を継続できる状態であった。また、実施例８では、さらに［Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］の値を下げるような条件をとり、他は実施例７と同じで生産したところ、炭素繊維束の引張強度の低下は０．５ＧＰａとさらに良好であった。一方で、［Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］の値が４９と、４０を超えた比較例４では、生産開始直後の炭素繊維束の引張強度は６．２ＧＰａ、炭素繊維束の連続生産後の引張強度は５．３ＧＰａであり、引張強度の低下は０．９ＧＰａと大きく、耐炎化繊維束の単糸表面に多くの粉塵付着や傷が見られた。 These flame resistant fiber bundles were carbonized at a maximum temperature of 1420 ° C., and then subjected to electrolytic surface treatment and sizing treatment to produce carbon fiber bundles. In Example 7, the tensile strength of the carbon fiber bundle immediately after the start of production is 6.4 GPa, the tensile strength of the carbon fiber bundle after continuous production is 5.7 GPa, and the decrease in tensile strength is 0.7 GPa, Production could continue. Further, in Example 8, production was performed in the same manner as in Example 7 except that the condition [D × (W × V × L)] / [(S / 60) × 10 5 ] was further reduced. However, the decrease in tensile strength of the carbon fiber bundle was even better at 0.5 GPa. On the other hand, in Comparative Example 4 in which the value of [D × (W × V × L)] / [(S / 60) × 10 5 ] exceeded 49 and 40, the tensile strength of the carbon fiber bundle immediately after the start of production Is 6.2 GPa, the tensile strength after continuous production of carbon fiber bundles is 5.3 GPa, the decrease in tensile strength is as large as 0.9 GPa, and many dust adhesions and scratches are seen on the surface of the single yarn of the flame-resistant fiber bundle. It was.
これらの例における炭素繊維束の引張弾性率は２９３〜２９６ＧＰａの範囲であった。 The tensile elastic modulus of the carbon fiber bundle in these examples was in the range of 293 to 296 GPa.
（実施例９、比較例５）
アクリロニトリル９９．５モル％とイタコン酸０．５モル％が共重合してなる共重合体を、ジメチルスルホキシドを溶媒とする溶液重合法により製造し、アクリル系共重合体の含有率が２２質量％である紡糸原液を得た。この紡糸原液を、６０ ℃で、孔数４，０００の紡糸口金を用いて６０℃にコントロールした５０％ジメチルスルホキシドの水溶液からなる凝固浴に導入する湿式紡糸法により凝固させた。この際の計算ドラフトは、０．７に設定した。得られた凝固糸を、水洗、延伸、シリコーン系油剤付与した後、乾燥させ、スチーム延伸することで、製糸全延伸倍率を１５倍とし、単糸繊度０．７ｄｔｅｘ、単糸本数１２０００本のポリアクリロニトリル系繊維束を得た。
(Example 9, Comparative Example 5)
A copolymer obtained by copolymerizing 99.5 mol% of acrylonitrile and 0.5 mol% of itaconic acid was produced by a solution polymerization method using dimethyl sulfoxide as a solvent, and the content of the acrylic copolymer was 22% by mass. A spinning dope was obtained. This spinning dope was coagulated at 60 ° C. by a wet spinning method introduced into a coagulation bath consisting of an aqueous solution of 50% dimethyl sulfoxide controlled at 60 ° C. using a spinneret having a pore size of 4,000. The calculation draft at this time was set to 0.7. The obtained coagulated yarn was washed with water, drawn, applied with a silicone-based oil agent, dried, and then subjected to steam drawing, so that the total drawing ratio of yarn production was 15 times, the single yarn fineness was 0.7 dtex, and the number of single yarns was 12,000. An acrylonitrile fiber bundle was obtained.
用いたシリコーン系油剤は、アミノ変性されたジメチルシロキサン成分を、非シリコーン系界面活性剤を用いて水分散系としたものを用い、その耐熱性は２４％であった。 The silicone oil used was an amino-modified dimethylsiloxane component made into a water dispersion using a non-silicone surfactant, and its heat resistance was 24%.
このようにして得られたポリアクリロニトリル系繊維束を、炉内温度２２０〜２７０℃の横型熱風循環式耐炎化炉において、表１に示す条件で耐炎化処理を行い、連続生産を行った後、不活性化ガス雰囲気下熱処理して得られた炭素繊維束のストランド引張強度を測定した。また、耐炎化繊維束の単糸表面に付着した粉塵と傷の個数を電子顕微鏡で測定した。結果を表１に示す。このとき耐炎化繊維束を構成する単糸の算術平均表面粗さ（Ｒａ）を測定すると、２３．０ｎｍであった。 The polyacrylonitrile fiber bundle thus obtained was subjected to flameproofing treatment under the conditions shown in Table 1 in a horizontal hot air circulation type flameproofing furnace having an in-furnace temperature of 220 to 270 ° C., and after continuous production, The strand tensile strength of the carbon fiber bundle obtained by heat treatment in an inert gas atmosphere was measured. Further, the number of dust and scratches attached to the surface of the single yarn of the flame resistant fiber bundle was measured with an electron microscope. The results are shown in Table 1. At this time, when the arithmetic average surface roughness (Ra) of the single yarn constituting the flameproof fiber bundle was measured, it was 23.0 nm.
実施例９では、糸幅、風速を比較的低く設定し、糸が通過するローラーのいくつかをパスする糸道を作成することで糸が通過する炉長を変更し、[Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］の値が５〜４０になるような条件にて生産を行ったところ、生産開始直後の炭素繊維束の引張強度が高く、さらに引張強度の低下の幅も小さかった。一方、糸速、風速を比較的高く設定し、[Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］の値が４０よりも大きい比較例５では特に連続生産を行った後の炭素繊維束の引張強度の低下が大きくなった。 In Example 9, the furnace width through which the yarn passes is changed by setting the yarn width and wind speed relatively low, and creating a yarn path that passes through some of the rollers through which the yarn passes, and [D × (W × V × L)] / [(S / 60) × 10 5 ] was produced under conditions such that the value was 5 to 40, and the tensile strength of the carbon fiber bundle immediately after the start of production was high. The range of strength reduction was also small. On the other hand, in comparative example 5 in which the yarn speed and wind speed are set relatively high and the value of [D × (W × V × L)] / [(S / 60) × 10 5 ] is larger than 40, continuous production is particularly preferred. The decrease in the tensile strength of the carbon fiber bundle after the increase was increased.
なお、これらの例では、炭素繊維束の引張弾性率は２９４ＧＰａであった。 In these examples, the tensile elastic modulus of the carbon fiber bundle was 294 GPa.
Claims (12)
［Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］ （式１）
の値が５〜４０である条件下で加熱処理することを特徴とする耐炎化繊維束の製造方法。
但し、（式１）において、
Ｄ：前記熱処理炉内に存在する粒径０．３μｍ以上の微粒子の濃度［個／リットル］
Ｗ：明細書中に定義される繊維束の幅［ｃｍ／ストランド］
Ｖ：繊維束を通過する循環熱風の風速［ｍ／秒］
Ｌ：繊維束が通過する炉長をＬ［ｍ］
Ｓ：繊維束の炉内通過速度［ｍ／分］ A single yarn fineness of 0.4 to 1.6 dtex, a filament number of 1000, to which an oxidizing gas having a concentration of fine particles having a particle size of 0.3 μm or more of 300 to 2500 / liter, a silicone-based oil containing amino-modified silicone is applied. When heat-treating the polyacrylonitrile fiber bundle at 200 to 300 ° C. in a heat treatment furnace that circulates in a direction perpendicular to the traveling direction of -80000 polyacrylonitrile fiber bundles,
[D × (W × V × L)] / [(S / 60) × 10 5 ] (Formula 1)
A method for producing a flame-resistant fiber bundle, wherein the heat treatment is carried out under the condition of a value of 5 to 40.
However, in (Formula 1):
D: Concentration of particles having a particle size of 0.3 μm or more existing in the heat treatment furnace [piece / liter]
W: width of the fiber bundle defined in the specification [cm / strand]
V: Wind speed of circulating hot air passing through the fiber bundle [m / sec]
L: The furnace length through which the fiber bundle passes is L [m]
S: Passing speed of the fiber bundle in the furnace [m / min]
［Ｄ×（Ｗ×Ｖ×Ｌ）］／［（Ｓ／６０）×１０５］ （式１）
の値が５〜４０である条件下で加熱処理することによって、単糸直径が６〜１３μｍ、明細書中に定義される繊維束の糸幅が１糸条あたり０．５〜１．０ｃｍ、密度が１．３４〜１．４０ｇ／ｃｍ３の耐炎化繊維束を得る方法であって、該耐炎化繊維束は、明細書中に定義される単糸表面に観察されるＳｉ、Ｃ、Ｎａ、Ｍｇ、Ａｌ、Ｋ、Ｃａ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｚｎのいずれかを主成分とし、かつ粒径が０．３μｍ以上である微粒子の個数と、明細書中に定義される０．３μｍ以上の単糸表面の傷の個数の合計が観察面積０．１ｍｍ２あたり１５個以下であることを特徴とする耐炎化繊維束の製造方法。
但し、（式１）において、
Ｄ：前記熱処理炉内に存在する粒径０．３μｍ以上の微粒子の濃度［個／リットル］
Ｗ：明細書中に定義される繊維束の幅［ｃｍ／ストランド］
Ｖ：繊維束を通過する循環熱風の風速［ｍ／秒］
Ｌ：繊維束が通過する炉長をＬ［ｍ］
Ｓ：繊維束の炉内通過速度［ｍ／分］ Heat treatment in which an oxidizing gas having a number of fine particles having a particle size of 0.3 μm or more of 300 to 2500 / liter is circulated in a direction perpendicular to the running direction of the polyacrylonitrile fiber bundle to which the silicone oil containing amino-modified silicone is applied. When the polyacrylonitrile fiber bundle is heat-treated at 200 to 300 ° C. in a furnace,
[D × (W × V × L)] / [(S / 60) × 10 5 ] (Formula 1)
By performing the heat treatment under the condition of a value of 5 to 40, the single yarn diameter is 6 to 13 μm, and the yarn width of the fiber bundle defined in the specification is 0.5 to 1.0 cm per yarn, A method for obtaining a flame-resistant fiber bundle having a density of 1.34 to 1.40 g / cm 3, wherein the flame-resistant fiber bundle is observed on the surface of a single yarn as defined in the specification. , Mg, Al, K, Ca, Mn, Fe, Co, Ni, Zn, and the number of fine particles having a particle size of 0.3 μm or more as defined in the specification. A method for producing a flame-resistant fiber bundle, wherein the total number of scratches on the surface of a single yarn of 3 μm or more is 15 or less per observation area of 0.1 mm 2 .
However, in (Formula 1):
D: Concentration of particles having a particle size of 0.3 μm or more existing in the heat treatment furnace [piece / liter]
W: width of the fiber bundle defined in the specification [cm / strand]
V: Wind speed of circulating hot air passing through the fiber bundle [m / sec]
L: The furnace length through which the fiber bundle passes is L [m]
S: Passing speed of the fiber bundle in the furnace [m / min]
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