JP2013103992A - Polyacrylonitrile-based copolymer for carbon fiber precursor fiber - Google Patents
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Abstract
Description
本発明は、炭素繊維前駆体繊維の原料となるポリアクリロニトリル系共重合体に関する。 The present invention relates to a polyacrylonitrile-based copolymer that is a raw material for carbon fiber precursor fibers.
炭素繊維の製造コストの低減を目的として、糸の総繊度を上げて生産性を改善しようとすると、実用面および生産技術の面で問題が多く、十分なコスト削減ができていなかった。特に単繊維繊度を大きくして糸の総繊度をあげると炭素繊維前駆体繊維の製造コストは大きく下がるが耐炎化処理時の耐炎化糸断面二重構造が顕著になり、炭素繊維の性能が大きく低下してしまうことが分かっている。 In order to improve the productivity by increasing the total fineness of the yarn for the purpose of reducing the production cost of the carbon fiber, there are many problems in terms of practical use and production technology, and the cost cannot be sufficiently reduced. In particular, if the single fiber fineness is increased to increase the total fineness of the yarn, the production cost of the carbon fiber precursor fiber is greatly reduced, but the double structure of the flameproof yarn cross section during the flameproofing treatment becomes prominent, and the performance of the carbon fiber increases. It is known that it will decline.
これらの問題を解決するため、特許文献１は、熱流速型示差走査熱量計にて炭素繊維前駆体繊維の等温発熱曲線を測定することで、カルボン酸基含有ビニルモノマーの含有量を適正化し、高速焼成を行っても耐炎化処理後の断面二重構造を抑制し、炭素繊維束の生産性と弾性率を両立することが出来る技術を提案している。 In order to solve these problems, Patent Document 1 optimizes the content of the carboxylic acid group-containing vinyl monomer by measuring the isothermal exothermic curve of the carbon fiber precursor fiber with a thermal flow rate differential scanning calorimeter, We have proposed a technology that can suppress the double structure of the cross-section after the flameproofing treatment and achieve both the productivity and the elastic modulus of the carbon fiber bundle even when performing high-speed firing.
特許文献２は、耐炎化処理が施されたポリマーを用いることで、単繊維繊度が大きな炭素繊維前駆体繊維の耐炎化処理においても、焼け斑を抑制し、更に、総繊度が大きいにも拘わらず単繊維間の交絡が少なく、広がり性に優れ、生産性にも優れた炭素繊維束を得る技術を提案している。 Patent Document 2 uses a polymer that has been subjected to flameproofing treatment, so that even in the flameproofing treatment of carbon fiber precursor fibers having a large single fiber fineness, burn-in spots are suppressed, and furthermore, the total fineness is large. We have proposed a technique for obtaining carbon fiber bundles that have few interlaces between single fibers, excellent spreadability, and excellent productivity.
また、特許文献３は、共重合体の共重合成分として嵩高い側鎖を有するモノマーを使用することにより、炭素繊維前駆体繊維の酸素透過性を向上させて耐炎化繊維内の酸素濃度分布を均一に制御し、得られる炭素繊維の引張強度および引張弾性率を向上させる技術を提案している。 In addition, Patent Document 3 uses a monomer having a bulky side chain as a copolymer component of the copolymer, thereby improving the oxygen permeability of the carbon fiber precursor fiber and the oxygen concentration distribution in the flame resistant fiber. A technique for improving the tensile strength and tensile modulus of the carbon fiber obtained by uniformly controlling the carbon fiber is proposed.
一方で、炭素繊維の製造コストの低減には、工程安定化も非常に重要な技術である。例えば、紡糸工程における紡糸原液のゲル化は、工程トラブルに直接繋がるものであり、紡糸原液の熱安定性向上が求められている。特許文献４は、ポリマーの耐炎化反応促進成分であるメタクリル酸をエステル化することで、紡糸原液を８０℃程度の高温で保持した際の熱安定性を飛躍的に向上させている。 On the other hand, process stabilization is also a very important technique for reducing the production cost of carbon fibers. For example, the gelation of the spinning dope in the spinning process directly leads to a process trouble, and improvement in the thermal stability of the spinning dope is required. Patent Document 4 dramatically improves the thermal stability when the spinning dope is held at a high temperature of about 80 ° C. by esterifying methacrylic acid, which is a component for promoting the flame resistance reaction of the polymer.
上記の各特許文献に記載の発明は以下の点で欠点を有するものであった。
特許文献１の技術では、単繊維繊度が１．２ｄｔｅｘ程度の小さい炭素繊維前駆体繊維については、高速焼成を行っても耐炎化繊維の断面二重構造を抑制することは出来るが、単繊維繊度２．５ｄｔｅｘ等の単繊維繊度の大きい炭素繊維前駆体繊維については、断面二重構造を抑制することは出来なかった。
The inventions described in the above patent documents have drawbacks in the following points.
In the technique of Patent Document 1, the carbon fiber precursor fiber having a small single fiber fineness of about 1.2 dtex can suppress the double structure of the cross section of the flame-resistant fiber even if high-speed firing is performed. A carbon fiber precursor fiber having a large single fiber fineness such as 2.5 dtex could not suppress the double structure of the cross section.
特許文献２の技術では、耐炎化工程そのものは短縮されるものの、ポリマーを耐炎化処理するという工程が必要であるため、炭素繊維の製造工程全体は短縮されなかった。 In the technique of Patent Document 2, although the flameproofing process itself is shortened, a process of flameproofing the polymer is necessary, and thus the entire carbon fiber manufacturing process has not been shortened.
特許文献３の技術では、酸素の繊維内部への透過性は改善されるものの、耐炎化工程の短縮による低コスト化には至らなかった。また、共重合体に用いられた嵩高いアルキル基を有するメタクリル酸エステル系のモノマーでは、炭素繊維前駆体繊維が炭素繊維の性能発現を確保するのに十分な緻密性あるいは均質性を保持できないという問題があった。 In the technique of Patent Document 3, although the permeability of oxygen into the fiber is improved, the cost has not been reduced by shortening the flameproofing process. Further, in the case of a methacrylic acid ester monomer having a bulky alkyl group used in a copolymer, the carbon fiber precursor fiber cannot maintain sufficient denseness or homogeneity to ensure the performance of the carbon fiber. There was a problem.
特許文献４の技術では、紡糸原液の熱安定性は飛躍的に向上するものの、単繊維繊度が大きい炭素繊維前駆体繊維が炭素繊維の性能発現を確保するのに十分な緻密性あるいは均質性を保持できないという問題があった。 In the technique of Patent Document 4, although the thermal stability of the spinning dope is dramatically improved, the carbon fiber precursor fiber having a large single fiber fineness has sufficient density or homogeneity to ensure the performance of the carbon fiber. There was a problem that it could not be held.
本発明は、単繊維繊度が大きい炭素繊維前駆体繊維であっても、焼成工程において耐炎化繊維の断面二重構造が抑制され、高性能な炭素繊維を、効率良く生産することが出来る炭素繊維前駆体繊維を提供することを目的とする。 The present invention is a carbon fiber capable of efficiently producing a high-performance carbon fiber, even if it is a carbon fiber precursor fiber having a large single fiber fineness, in which the cross-sectional double structure of the flameproof fiber is suppressed in the firing step. An object is to provide a precursor fiber.
前記目的は以下の本発明によって解決される。 The object is solved by the present invention described below.
本発明のポリアクリロニトリル系共重合体は、アクリロニトリル単位９６〜９７．５質量部と、アクリルアミド単位２．５〜４質量部と、カルボン酸含有ビニル系モノマー０．０１〜０．４質量部とからなる。 The polyacrylonitrile copolymer of the present invention comprises 96 to 97.5 parts by mass of acrylonitrile units, 2.5 to 4 parts by mass of acrylamide units, and 0.01 to 0.4 parts by mass of a carboxylic acid-containing vinyl monomer. Become.
本発明のポリアクリロニトリル系共重合体は、カルボキシル基が０.１×１０−５〜４．０×１０−５ｍｏｌ／ｇ含有するのが好ましい。 The polyacrylonitrile copolymer of the present invention preferably contains 0.1 × 10 −5 to 4.0 × 10 −5 mol / g of a carboxyl group.
本発明のポリアクリロニトリル系共重合体は、以下の方法により得られる酸化深さＤが３．５〜４．５μｍであることが好ましい。
酸化深さＤの測定方法
１）前記ポリアクリロニトリル共重合体をジメチルホルムアミドに、質量濃度で２５％となるよう溶解させて共重合体溶液を得る。
２）前記共重合体溶液をガラス板上に一定の厚みになるように塗布する。
３）前記共重合体溶液を塗布したガラス板を、空気中１２０℃で６時間乾燥し、厚み２０〜４０μｍのフィルムとする。
４）得られたフィルムを、空気中２４０℃で６０分、さらに空気中２５０℃で６０分熱処理し、耐炎化処理を行う。
５）耐炎化処理したフィルムを樹脂包埋して、該樹脂を固化した上で、前記フィルム表面に対して垂直方向を研磨して断面を得て、そのフィルム断面を蛍光顕微鏡を用いて倍率１５００倍で観察する。
６）前記断面において酸化が進んだ部分は暗い層として、進んでいない部分は明るい層として観察されるので、フィルム表面から、暗い層と明るい層の境界までの距離を５点計測し、その算術平均を酸化深さＤ（μｍ）とする。
The polyacrylonitrile-based copolymer of the present invention preferably has an oxidation depth D of 3.5 to 4.5 μm obtained by the following method.
Measuring method of oxidation depth D 1) The polyacrylonitrile copolymer is dissolved in dimethylformamide so as to have a mass concentration of 25% to obtain a copolymer solution.
2) The copolymer solution is applied on a glass plate so as to have a certain thickness.
3) The glass plate coated with the copolymer solution is dried in air at 120 ° C. for 6 hours to obtain a film having a thickness of 20 to 40 μm.
4) The obtained film is heat-treated at 240 ° C. in air for 60 minutes and further in air at 250 ° C. for 60 minutes to perform flameproofing treatment.
5) A flame-resistant film is embedded in a resin, and the resin is solidified, and then a cross section is obtained by polishing the direction perpendicular to the film surface. The cross section of the film is magnified 1500 using a fluorescence microscope. Observe at double.
6) In the cross section, the portion where oxidation has progressed is observed as a dark layer, and the portion where oxidation has not progressed is observed as a bright layer. Therefore, the distance from the film surface to the boundary between the dark layer and the bright layer is measured at five points. The average is defined as oxidation depth D (μm).
本発明の炭素繊維前駆体繊維は、前記ポリアクリロニトリル系共重合体からなる炭素繊維前駆体繊維であって熱流束型示差走査熱量計により、１００ｍｌ／分の空気気流中で昇温速度１０℃／分として３０℃から４５０℃まで測定された炭素繊維前駆体繊維の２３０℃から２６０℃までの発熱量Ａが３０〜６０ＫＪ／Ｋｇであり、２６０℃から２９０℃までの発熱量Ｂが８００〜９５０ＫＪ／Ｋｇであることが好ましい。 The carbon fiber precursor fiber of the present invention is a carbon fiber precursor fiber made of the polyacrylonitrile-based copolymer, and the temperature rising rate is 10 ° C./min in an air stream of 100 ml / min by a heat flux type differential scanning calorimeter. The calorific value A from 230 ° C. to 260 ° C. of the carbon fiber precursor fiber measured from 30 ° C. to 450 ° C. is 30 to 60 KJ / Kg, and the calorific value B from 260 ° C. to 290 ° C. is 800 to 950 KJ. / Kg is preferable.
本発明の炭素繊維前駆体繊維は、単繊維繊度が、２〜５ｄｔｅｘであることが好ましい。 The carbon fiber precursor fiber of the present invention preferably has a single fiber fineness of 2 to 5 dtex.
本発明によれば、単繊維繊度が大きく優れた生産性を有するにもかかわらず、性能発現性に優れた炭素繊維の製造に適した炭素繊維前駆体繊維用ポリアクリロニトリル系共重合体が提供される。 According to the present invention, there is provided a polyacrylonitrile-based copolymer for carbon fiber precursor fibers that is suitable for producing carbon fibers having excellent performance despite the fact that the single fiber fineness is large and has excellent productivity. The
＜炭素繊維前駆体繊維用ポリアクリロニトリル系共重合体＞
本発明の炭素繊維前駆体繊維用ポリアクリロニトリル共重合体は、アクリロニトリル単位９６〜９７．５質量部と、アクリルアミド単位２．５〜４質量部と、カルボン酸含有ビニル系モノマー０．０１〜０．４質量部とからなる。
本発明の炭素繊維前駆体繊維用ポリアクリロニトリル共重合体はアクリロニトリル単位を９６〜９７．５質量部含むことが好ましい。炭素繊維前駆体繊維用ポリアクリロニトリル共重合体中のアクリロニトリル単位を９６質量部以上とすることで炭素繊維前駆体繊維を製造する上で繊維の乾燥工程または加熱ローラーや加熱水蒸気下での延伸工程での単繊維間の融着および焼成工程での熱融着や炭素繊維の性能、品質低下を防ぐことができる。 また、炭素繊維前駆体繊維用ポリアクリロニトリル共重合体中のアクリロニトリル単位を９７．５質量部以下とすることで溶剤への溶解性を十分確保でき、炭素繊維前駆体繊維用ポリアクリロニトリル共重合体の紡糸原液中への析出を防ぐことができる。
本発明の炭素繊維前駆体繊維用ポリアクリロニトリル共重合体はアクリルアミド単位を２．５〜４．０質量部含むことが好ましい。炭素繊維前駆体繊維用ポリアクリロニトリル共重合体中のアクリルアミド単位を２．５質量部以上とすることで炭素繊維前駆体繊維の緻密性が向上し、優れた性能の炭素繊維を得ることができる。また、炭素繊維前駆体繊維用ポリアクリロニトリル共重合体中のアクリルアミド単位を４．０質量部以下とすることで炭素繊維前駆体繊維用ポリアクリロニトリル共重合体中のアクリロニトリル含有量が十分確保でき、炭素繊維前駆体繊維を製造する上で繊維の乾燥工程または加熱ローラーや加熱水蒸気下での延伸工程での単繊維間の融着および焼成工程での熱融着や炭素繊維の性能、品質低下を防ぐことができる。
本発明の炭素繊維前駆体繊維用ポリアクリロニトリル共重合体はカルボン酸含有ビニル系モノマー単位を０．０１〜０．４質量部含むことが好ましい。炭素繊維前駆体繊維用ポリアクリロニトリル共重合体中のカルボン酸含有ビニル系モノマー単位を０．０１質量部以上とすることで焼成工程での熱融着や炭素繊維の性能、品質低下を防ぐことができる。また、炭素繊維前駆体繊維用ポリアクリロニトリル共重合体中のカルボン酸含有ビニル系モノマー単位を０．４質量部以下とすることで耐炎化反応時に断面二重構造の形成を抑制することが可能になる。
<Polyacrylonitrile copolymer for carbon fiber precursor fiber>
The polyacrylonitrile copolymer for carbon fiber precursor fiber of the present invention has 96 to 97.5 parts by mass of acrylonitrile units, 2.5 to 4 parts by mass of acrylamide units, and 0.01 to 0. 4 parts by mass.
The polyacrylonitrile copolymer for carbon fiber precursor fibers of the present invention preferably contains 96 to 97.5 parts by mass of acrylonitrile units. In producing a carbon fiber precursor fiber by setting the acrylonitrile unit in the polyacrylonitrile copolymer for carbon fiber precursor fiber to 96 parts by mass or more, in a fiber drying step or a drawing step under a heating roller or heating steam It is possible to prevent fusion between single fibers and heat fusion in the firing step, and performance and quality degradation of the carbon fiber. In addition, by setting the acrylonitrile unit in the polyacrylonitrile copolymer for carbon fiber precursor fibers to 97.5 parts by mass or less, sufficient solubility in a solvent can be secured, and the polyacrylonitrile copolymer for carbon fiber precursor fibers can be obtained. Precipitation into the spinning dope can be prevented.
The polyacrylonitrile copolymer for carbon fiber precursor fiber of the present invention preferably contains 2.5 to 4.0 parts by mass of acrylamide units. By setting the acrylamide unit in the polyacrylonitrile copolymer for carbon fiber precursor fibers to 2.5 parts by mass or more, the density of the carbon fiber precursor fibers is improved, and carbon fibers having excellent performance can be obtained. Further, by setting the acrylamide unit in the polyacrylonitrile copolymer for carbon fiber precursor fibers to 4.0 parts by mass or less, the acrylonitrile content in the polyacrylonitrile copolymer for carbon fiber precursor fibers can be sufficiently secured, and carbon When producing fiber precursor fibers, prevent fusion between single fibers in the fiber drying process or stretching process under a heated roller or heated steam, and heat fusion in the firing process, carbon fiber performance and quality degradation. be able to.
The polyacrylonitrile copolymer for carbon fiber precursor fibers of the present invention preferably contains 0.01 to 0.4 parts by mass of a carboxylic acid-containing vinyl monomer unit. By making the carboxylic acid-containing vinyl-based monomer unit in the polyacrylonitrile copolymer for carbon fiber precursor fibers 0.01 parts by mass or more, heat fusion in the firing process and performance and quality deterioration of the carbon fiber can be prevented. it can. In addition, by making the carboxylic acid-containing vinyl monomer unit in the polyacrylonitrile copolymer for carbon fiber precursor fibers 0.4 mass part or less, it is possible to suppress the formation of a double structure in the cross section during the flameproofing reaction. Become.
さらに本発明では炭素繊維前駆体繊維用ポリアクリロニトリル共重合体中に０.１×１０−５〜４．０×１０−５ｍｏｌ／ｇのカルボキシル基を有するようカルボン酸含有ビニル系モノマーを含むことが好ましい。炭素繊維前駆体繊維用ポリアクリロニトリル共重合体中のカルボキシル基含有量が０．１×１０−５ｍｏｌ／ｇ以上であれば耐炎化反応において耐炎化反応を十分促進させることができる。また、炭素繊維前駆体繊維用ポリアクリロニトリル共重合体中のカルボキシル基含有量が４．０×１０−５ｍｏｌ／ｇ以下であれば単繊維繊度２〜５ｄｔｅｘの単繊維繊度の大きい炭素繊維前駆体繊維を耐炎化処理する工程において耐炎化反応の暴走を抑制することが可能になる。これらの観点から炭素繊維前駆体繊維用ポリアクリロニトリル共重合体中のカルボキシル基含有量は０．５×１０−５〜１．５×１０−５ｍｏｌ／ｇとすることがより好ましい。 Further, in the present invention, the polyacrylonitrile copolymer for carbon fiber precursor fiber contains a carboxylic acid-containing vinyl monomer so as to have a carboxyl group of 0.1 × 10 −5 to 4.0 × 10 −5 mol / g. Is preferred. If the carboxyl group content in the polyacrylonitrile copolymer for carbon fiber precursor fibers is 0.1 × 10 −5 mol / g or more, the flameproofing reaction can be sufficiently accelerated in the flameproofing reaction. Moreover, if the carboxyl group content in the polyacrylonitrile copolymer for carbon fiber precursor fibers is 4.0 × 10 −5 mol / g or less, the carbon fiber precursor having a single fiber fineness of 2 to 5 dtex and a large single fiber fineness. It becomes possible to suppress the runaway of the flameproofing reaction in the process of flameproofing the fiber. From these viewpoints, the carboxyl group content in the polyacrylonitrile copolymer for carbon fiber precursor fibers is more preferably 0.5 × 10 −5 to 1.5 × 10 −5 mol / g.
カルボン酸含有ビニル系単量体としては、アクリル酸、メタクリル酸、イタコン酸、クロトン酸、シトラコン酸、エタクリル酸、マレイン酸、メサコン酸又はこれらのアルカリ金属塩、アンモニウム塩が挙げられる。 Examples of the carboxylic acid-containing vinyl monomer include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, citraconic acid, ethacrylic acid, maleic acid, mesaconic acid, or alkali metal salts and ammonium salts thereof.
炭素繊維前駆体繊維用ポリアクリロニトリル共重合体の酸化深さＤは次のようにして定義、測定される。まず、共重合体をジメチルホルムアミドに、重量濃度で２５％となるよう溶解し、次に該溶液をガラス板上にキャストして、一定の厚みになるように塗布する。 次に、重合体溶液を塗布したガラス板を、熱風乾燥機等を用いて、空気中１２０℃で６時間乾燥し、溶媒を蒸発させて、厚み２０〜４０μｍのフィルムとする。得られたフィルムを、熱風乾燥機等を用いて、空気中２４０℃で６０分、さらに空気中２５０℃で６０分熱処理し、耐炎化処理を行う。得られた耐炎化フィルムを樹脂包埋した上で研磨し、そのフィルム表面に対して垂直な断面を蛍光顕微鏡を用いて倍率１５００倍で観察する。断面において酸化が進んだ部分は暗い層として、進んでいない部分は明るい層として観察されるので、フィルム表面から、暗い層と明るい層の境界までの距離を少なくとも５点計測し、その算術平均を酸化深さＤ（μｍ）とする The oxidation depth D of the polyacrylonitrile copolymer for carbon fiber precursor fiber is defined and measured as follows. First, the copolymer is dissolved in dimethylformamide so as to have a weight concentration of 25%, and then the solution is cast on a glass plate and applied to a certain thickness. Next, the glass plate coated with the polymer solution is dried in air at 120 ° C. for 6 hours using a hot air dryer or the like, and the solvent is evaporated to form a film having a thickness of 20 to 40 μm. The obtained film is heat-treated at 240 ° C. in air for 60 minutes and further in air at 250 ° C. for 60 minutes using a hot air dryer or the like to perform flameproofing treatment. The obtained flame resistant film is polished after being embedded in a resin, and a cross section perpendicular to the film surface is observed at a magnification of 1500 times using a fluorescence microscope. In the cross section, the part where oxidation has progressed is observed as a dark layer, and the part which has not progressed is observed as a bright layer. Therefore, measure the distance from the film surface to the boundary between the dark layer and the bright layer at least 5 points, and calculate the arithmetic average. Oxidation depth D (μm)
本発明の炭素繊維前駆体繊維用ポリアクリロニトリル共重合体の酸化深さＤは３．５〜４．５μｍであることが好ましい。酸化深さが３．５μｍ以上あれば単繊維繊度２〜５ｄｔｅｘ等の単繊維繊度の大きい炭素繊維前駆体繊維耐炎化処理工程において酸素を繊維内部まで十分に行き渡らせることが出来る酸素拡散性が得られ、高性能な炭素繊維を製造することが可能となる。一方、４．５μｍ以下であれば、耐炎化工程における酸化反応が過剰に進み、得られる炭素繊維の収率が低下することもなくなる。これらの観点から酸化深さＤは３．８〜４．２μｍとすることがより好ましい。 The oxidation depth D of the polyacrylonitrile copolymer for carbon fiber precursor fiber of the present invention is preferably 3.5 to 4.5 μm. If the oxidation depth is 3.5 μm or more, oxygen diffusibility can be obtained that can sufficiently distribute oxygen to the inside of the fiber in the carbon fiber precursor fiber flameproofing process with a large single fiber fineness such as a single fiber fineness of 2 to 5 dtex. This makes it possible to produce high-performance carbon fibers. On the other hand, if it is 4.5 μm or less, the oxidation reaction in the flameproofing process will proceed excessively, and the yield of the obtained carbon fiber will not decrease. From these viewpoints, the oxidation depth D is more preferably 3.8 to 4.2 μm.
＜炭素繊維前駆体繊維＞
本発明の炭素繊維前駆体繊維は、上述の炭素繊維前駆体繊維用ポリアクリロニトリル系共重合体を公知の方法で紡糸することによって製造することができる。
<Carbon fiber precursor fiber>
The carbon fiber precursor fiber of the present invention can be produced by spinning the above-mentioned polyacrylonitrile copolymer for carbon fiber precursor fiber by a known method.
炭素繊維前駆体繊維用ポリアクリロニトリル系共重合体を溶剤に溶解して、紡糸原液とする。溶剤としては、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を用いることができる。前駆体繊維中に金属を含有せず、また、工程が簡略化される点で有機溶剤が好ましく、その中でも凝固糸及び湿熱延伸糸の緻密性が高いという点で、ジメチルアセトアミドを用いることが好ましい。 A polyacrylonitrile-based copolymer for carbon fiber precursor fibers is dissolved in a solvent to obtain a spinning dope. As the solvent, organic solvents such as dimethylacetamide, dimethylsulfoxide, dimethylformamide, and aqueous solutions of inorganic compounds such as zinc chloride and sodium thiocyanate can be used. An organic solvent is preferable because it contains no metal in the precursor fiber and the process is simplified. Among them, dimethylacetamide is preferably used because the denseness of the coagulated yarn and wet heat drawn yarn is high. .
紡糸原液は、緻密な凝固糸を得るため、また、適正な粘度、流動性を有するために、ある程度以上の共重合体濃度を有することが好ましい。紡糸原液における共重合体の濃度は、１５〜３０質量％の範囲にあることが好ましく、より好ましくは１８〜２５質量％の範囲である。 The spinning dope preferably has a copolymer concentration of a certain level or more in order to obtain a dense coagulated yarn and to have an appropriate viscosity and fluidity. The concentration of the copolymer in the spinning dope is preferably in the range of 15 to 30% by mass, more preferably in the range of 18 to 25% by mass.
紡糸方法としては、公知の方法を採用でき、具体的には湿式紡糸法、乾湿式紡糸法、乾式紡糸法などが挙げられる。これらの中でも湿式紡糸法、乾湿式紡糸法が紡糸の生産性の観点、炭素繊維の強度発現性の観点から好ましく用いられる。 As the spinning method, a known method can be adopted, and specific examples include a wet spinning method, a dry wet spinning method, a dry spinning method, and the like. Among these, the wet spinning method and the dry wet spinning method are preferably used from the viewpoint of spinning productivity and the strength development of carbon fiber.
上記紡糸原液を、紡糸口金を介して凝固浴中に吐出して紡糸することで、凝固糸を得る。このときの凝固浴は、濃度３０〜７０質量％、温度２０〜５０℃の範囲にあるジメチルアセトアミド水溶液を用いることが好ましい。 The spinning solution is discharged and spun into a coagulation bath through a spinneret to obtain a coagulated yarn. As the coagulation bath at this time, a dimethylacetamide aqueous solution having a concentration of 30 to 70% by mass and a temperature of 20 to 50 ° C. is preferably used.
濃度が３０質量％以上であれば、凝固速度が適正な範囲に保たれ、凝固糸の急激な収縮が起こらず、糸の緻密性が保たれる。一方、濃度が７０質量％以下であれば、凝固速度が適正な範囲に保たれるので得られる前駆体繊維束の単糸間の接着が抑制できる。特に、単繊維繊度、総繊度の大きい前駆体繊維束を紡糸する際には、単糸間の接着をさらに抑制する点から、濃度は６５質量％以下が好ましい。 When the concentration is 30% by mass or more, the coagulation rate is maintained in an appropriate range, and the coagulated yarn does not rapidly contract, and the yarn is kept dense. On the other hand, if the concentration is 70% by mass or less, the coagulation rate is maintained in an appropriate range, so that adhesion between single yarns of the obtained precursor fiber bundle can be suppressed. In particular, when spinning a precursor fiber bundle having a large single fiber fineness and a total fineness, the concentration is preferably 65% by mass or less from the viewpoint of further suppressing adhesion between single yarns.
また、温度が２０℃以上であれば、凝固張力が適正な範囲に保たれるので、凝固浴中で単糸切れの発生が抑制できる。一方、温度を５０℃以下とすれば、前駆体繊維束を焼成して得られる炭素繊維のストランド強度の低下を抑制できる。ジメチルアセトアミド水溶液の温度は、２５〜４０℃がより好ましい。
得られた凝固糸をその後の工程で脱溶剤処理、浴中延伸処理、油剤付着処理、乾燥処理等を行い、さらにはスチーム延伸あるいは乾熱延伸等の後延伸処理を施すことで、前駆体繊維束を得ることができる。
Further, if the temperature is 20 ° C. or higher, the coagulation tension is maintained in an appropriate range, so that the occurrence of single yarn breakage can be suppressed in the coagulation bath. On the other hand, if the temperature is 50 ° C. or lower, it is possible to suppress a decrease in the strand strength of the carbon fiber obtained by firing the precursor fiber bundle. The temperature of the aqueous dimethylacetamide solution is more preferably 25 to 40 ° C.
The obtained coagulated yarn is subjected to solvent removal treatment, stretching treatment in the bath, oil agent adhesion treatment, drying treatment, etc. in the subsequent steps, and further subjected to post-stretching treatment such as steam drawing or dry heat drawing, so that the precursor fiber is obtained. You can get a bunch.
なお、前駆体繊維束の繊維構造の緻密性あるいは均質性が不十分な場合、焼成時に欠陥点となり、炭素繊維の性能を損なうことがある。緻密で均質な前駆体繊維束を得るには、この凝固糸の性状が極めて重要であり、前駆体繊維１ｍｍ長中にマクロボイドが１個未満であることが好ましい。ここで、マクロボイドとは、最大径が０．１〜数μｍの大きさを有する球形、紡錘形、円筒形を有する空隙を総称したものである。 In addition, when the denseness or homogeneity of the fiber structure of the precursor fiber bundle is insufficient, it becomes a defect point during firing and may impair the performance of the carbon fiber. In order to obtain a dense and homogeneous precursor fiber bundle, the properties of the coagulated yarn are extremely important, and it is preferable that the number of macrovoids is less than 1 in 1 mm of the precursor fiber. Here, the macro void is a general term for voids having a spherical shape, a spindle shape, or a cylindrical shape having a maximum diameter of 0.1 to several μm.
本発明における凝固糸は、このようなマクロボイドがなく、十分に均一な凝固によって得られたものである。マクロボイドが多く存在すると、凝固糸は失透して白濁するが、本発明の凝固糸にはマクロボイドがほとんど存在しないため失透せず白濁しにくい。 The coagulated yarn in the present invention does not have such macro voids and is obtained by sufficiently uniform coagulation. If there are many macrovoids, the coagulated yarn is devitrified and becomes cloudy. However, the coagulated yarn of the present invention is hardly devitrified and hardly clouded because there are almost no macrovoids.
マクロボイドの有無は、凝固糸を直接光学顕微鏡で観察するか、適切な方法で切断して断面を光学顕微鏡で観察することで容易に判断することができる。
得られた炭素繊維前駆体繊維は熱流束型示差走査熱量計で１００ｍｌ／分の空気気流中、昇温速度１０℃／分として３０℃から４５０℃まで測定された炭素繊維前駆体繊維の等速昇温発熱曲線の２３０℃から２６０℃までの発熱量Ａが４５〜６０ＫＪ／Ｋｇであって、２６０℃から２９０℃までの発熱量Ｂが８００〜９５０ＫＪ／Ｋｇであることが好ましい。
The presence or absence of macrovoids can be easily determined by observing the coagulated yarn directly with an optical microscope, or by cutting with a suitable method and observing the cross section with an optical microscope.
The obtained carbon fiber precursor fiber was measured at a constant velocity of the carbon fiber precursor fiber measured from 30 ° C. to 450 ° C. at a heating rate of 10 ° C./min in an air stream of 100 ml / min with a heat flux type differential scanning calorimeter. The heat generation amount A from 230 ° C. to 260 ° C. in the temperature rising heat generation curve is preferably 45 to 60 KJ / Kg, and the heat generation amount B from 260 ° C. to 290 ° C. is preferably 800 to 950 KJ / Kg.
熱量Ａは、前駆体繊維束の耐炎化工程前半における耐炎化反応性の指標である。
熱量Ａが４５ＫＪ／Ｋｇ以上であれば、耐炎化工程の初期において適度に耐炎化反応が進行し、前駆体繊維束を熱によって溶融させることなく工程を通過させることが可能である。また、６０ＫＪ／Ｋｇ以下であれば、耐炎化工程の初期において、耐炎化反応が一気に進行することなく、単繊維繊度の大きい前駆体繊維束においても均一に耐炎化処理することが可能である。
The amount of heat A is an index of flame resistance reactivity in the first half of the flame resistance process of the precursor fiber bundle.
When the amount of heat A is 45 KJ / Kg or more, the flameproofing reaction proceeds moderately at the initial stage of the flameproofing process, and it is possible to pass the process without melting the precursor fiber bundle. Moreover, if it is 60 KJ / Kg or less, a flame-proofing process can be performed uniformly also in the precursor fiber bundle with a large single fiber fineness, without a flame-proofing reaction progressing at a stretch in the early stage of a flame-proofing process.
一方、熱量Ｂは、前駆体繊維束の耐炎化工程後半における耐炎化反応性の指標である。
熱量Ｂが８００ＫＪ／Ｋｇ以上であれば、耐炎化工程において生産性を損なうことなく目標耐炎化糸密度まで前駆体繊維束を耐炎化処理することが可能である。また、９５０ＫＪ／Ｋｇ以下であれば、耐炎化工程において、耐炎化反応が緩やかに進行するため、単繊維繊度の大きい前駆体繊維束を均一に耐炎化処理することができ、断面二重構造の形成を抑制することが可能である。
On the other hand, the heat quantity B is an index of flame resistance reactivity in the latter half of the flame resistance process of the precursor fiber bundle.
When the amount of heat B is 800 KJ / Kg or more, the precursor fiber bundle can be flameproofed to the target flameproof yarn density without impairing productivity in the flameproofing step. Moreover, if it is 950 KJ / Kg or less, in a flame-proofing process, since a flame-proofing reaction will advance slowly, the precursor fiber bundle with a large single fiber fineness can be uniformly flame-proofed, and it has a double-section structure. Formation can be suppressed.
本発明の炭素繊維前駆体繊維の単繊維繊度は、２〜５ｄｔｅｘが好ましい。２ｄｔｅｘ以上であれば、効率良く生産することが出来やすくなり、５ｄｔｅｘ以下であれば、焼成工程において耐炎化繊維の断面二重構造が抑制されやすくなる。前記単繊維繊度は、２．５〜４ｄｔｅｘがさらに好ましい。 The single fiber fineness of the carbon fiber precursor fiber of the present invention is preferably 2 to 5 dtex. If it is 2 dtex or more, it becomes easy to produce efficiently, and if it is 5 dtex or less, the cross-sectional double structure of a flame-resistant fiber will become easy to be suppressed in a baking process. The single fiber fineness is more preferably 2.5 to 4 dtex.
本発明により得られる炭素繊維前駆体繊維用ポリアクリロニトリル系共重合体を用いて得られた炭素繊維前駆体繊維は単繊維繊度が大きい場合においても、焼成工程において耐炎化繊維の断面二重構造が抑制され、高性能かつ高品位な炭素繊維を、効率良く生産することが出来る。 Even when the carbon fiber precursor fiber obtained by using the polyacrylonitrile-based copolymer for carbon fiber precursor fiber obtained according to the present invention has a large single fiber fineness, the cross-sectional double structure of the flame resistant fiber in the firing process is Suppressed, high-performance and high-quality carbon fiber can be produced efficiently.
以下、本発明について実施例を挙げて具体的に説明するが、本発明はこれらに限定されるものではない。 EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these.
［ポリアクリロニトリル系共重合体の組成］
ポリアクリロニトリル系共重合体の組成（各単量体単位の比率（質量％））は、１Ｈ−ＮＭＲ法により、以下のようにして測定した。溶媒としてジメチルスルホキシド−ｄ６溶媒を用い、共重合体を溶解させ、ＮＭＲ測定装置（日本電子社製、製品名：ＧＳＺ−４００型）により、積算回数４０回、測定温度１２０℃の条件で測定し、ケミカルシフトの積分比から各単量体単位の比率を求めた。
[Composition of polyacrylonitrile copolymer]
The composition of polyacrylonitrile-based copolymer (ratio (mass%) of each monomer unit) was measured by 1 H-NMR method as follows. Using dimethyl sulfoxide -d 6 solvent as a solvent to dissolve the copolymer, NMR measuring apparatus (manufactured by JEOL Ltd., product name: GSZ-400 type), the number of integration 40 times, measured under the conditions of measurement temperature 120 ° C. The ratio of each monomer unit was determined from the chemical shift integral ratio.
［ポリアクリロニトリル系共重合体中のカルボキシル基の当量］
ポリアクリロニトリル系共重合体中のカルボキシル基の当量（含有量）は、測定した１Ｈ−ＮＭＲの結果より得られた共重合体の組成比からカルボキシル基のモル当量を算出し、共重合体１ｇ当りに換算した。
[Equivalent of carboxyl group in polyacrylonitrile copolymer]
The equivalent (content) of the carboxyl group in the polyacrylonitrile-based copolymer was calculated by calculating the molar equivalent of the carboxyl group from the composition ratio of the copolymer obtained from the measured 1 H-NMR result, and 1 g of copolymer. Converted per hit.
［ポリアクリロニトリル系共重合体の酸化深さＤの測定］
ポリアクリロニトリル系共重合体をジメチルホルムアミドに、重量濃度で２５％となるよう溶解し、次に該溶液をガラス板上にキャストして、一定の厚みになるように塗布する。次に、重合体溶液を塗布したガラス板を、熱風乾燥機等を用いて、空気中１２０℃で６時間乾燥し、溶媒を蒸発させて、厚み２０〜４０μｍのフィルムとする。得られたフィルムを、熱風乾燥機等を用いて、空気中２４０℃で６０分、さらに空気中２５０℃で６０分熱処理し、耐炎化処理を行う。得られた耐炎化フィルムを樹脂包埋した上で研磨し、そのフィルム表面に対して垂直な断面を蛍光顕微鏡（ＭＩＣＲＯＦＬＥＸ ＡＦＸ ＤＸ）を用いて倍率１５００倍で観察する。断面において酸化が進んだ部分は暗い層として、進んでいない部分は明るい層として観察されるので、フィルム表面から、暗い層と明るい層の境界までの距離を少なくとも５点計測し、その算術平均値を酸化深さＤ（μｍ）とした。
[Measurement of oxidation depth D of polyacrylonitrile-based copolymer]
A polyacrylonitrile-based copolymer is dissolved in dimethylformamide so as to have a weight concentration of 25%, and then the solution is cast on a glass plate and applied to a certain thickness. Next, the glass plate coated with the polymer solution is dried in air at 120 ° C. for 6 hours using a hot air dryer or the like, and the solvent is evaporated to form a film having a thickness of 20 to 40 μm. The obtained film is heat-treated at 240 ° C. in air for 60 minutes and further in air at 250 ° C. for 60 minutes using a hot air dryer or the like to perform flameproofing treatment. The obtained flame resistant film is polished after being embedded in a resin, and a cross section perpendicular to the film surface is observed at a magnification of 1500 times using a fluorescence microscope (MICROFLEX AFX DX). In the cross section, the portion where oxidation has progressed is observed as a dark layer, and the portion where oxidation has not progressed is observed as a bright layer. Therefore, measure the distance from the film surface to the boundary between the dark layer and the bright layer at least 5 points, and the arithmetic average value Was defined as an oxidation depth D (μm).
［炭素繊維前駆体繊維の等速昇温発熱曲線］
炭素繊維前駆体繊維の等速昇温発熱曲線は、熱流束型示差走査熱量計により、以下のようにして測定した。炭素繊維前駆体繊維を４．０ｍｍの長さに切断し、４．０ｍｇを精秤して、エスアイアイ社製の密封試料容器Ａｇ製５０μｌ（Ｐ／Ｎ ＳＳＣ０００Ｅ０３０）に詰め、エスアイアイ社製メッシュカバーＣｕ製（Ｐ／Ｎ ５０−０３７）（４５０℃／１５分間、空気中で熱処理済）で蓋をした。エスアイアイ社製ＤＳＣ／２２０を用いて、１０℃／分の昇温速度、エアー供給量１００ｍｌ／ｍｉｎの条件で、室温から４５０℃まで測定し、得られた等速昇温発熱曲線の２３０℃〜２６０℃の発熱量を熱量Ａとし、２６０℃〜２９０℃の発熱量を熱量Ｂとした。
[Constant temperature rise exothermic curve of carbon fiber precursor fiber]
The constant temperature heating exothermic curve of the carbon fiber precursor fiber was measured with a heat flux type differential scanning calorimeter as follows. The carbon fiber precursor fiber was cut into a length of 4.0 mm, and 4.0 mg was precisely weighed and packed in 50 μl (P / N SSC000E030) of a sealed sample container Ag manufactured by SII, and a mesh manufactured by SII. The cover was made of Cu (P / N 50-037) (450 ° C./15 minutes, heat-treated in air). Measured from room temperature to 450 ° C. using a DSC / 220 manufactured by SII Corporation under the conditions of a temperature rising rate of 10 ° C./min and an air supply rate of 100 ml / min, 230 ° C. of the obtained constant speed heating exothermic curve A calorific value of ˜260 ° C. was defined as a calorific value A, and a calorific value of 260 ° C.-290 ° C. was defined as a calorific value B.
[前駆体繊維束の単繊維繊度]
単繊維繊度とは、繊維１本の１００００ｍ当りの重さである。前駆体繊維束を１ｍずつ２本とり、各々の質量をフィラメント数（すなわち口金の孔数）で除した後、１００００倍し、２本の平均値を単繊維繊度とした。
[Single fiber fineness of precursor fiber bundle]
The single fiber fineness is the weight per 10,000 m of one fiber. Two precursor fiber bundles were taken 1 m at a time, and each mass was divided by the number of filaments (that is, the number of holes in the die), and then multiplied by 10000 to obtain the average value of the two as the single fiber fineness.
（実施例１）
［ポリアクリロニトリル系共重合体の製造］
容量８０リットルのタービン撹拌翼付きアルミニウム製重合釜（攪拌翼：２４０φ、５５ｍｍ×５７ｍｍの２段４枚羽）に、脱イオン交換水が重合釜オーバーフロー口まで達するよう７６．５リットル入れ、硫酸第一鉄（Ｆｅ２ＳＯ４・７Ｈ２Ｏ）を０．０１ｇ加え、反応液のｐＨが３．０になるように硫酸を用いて調節し、重合釜内の温度を５７℃で保持した。
Example 1
[Production of polyacrylonitrile copolymer]
Place 76.5 liters of deionized water in an aluminum polymerization kettle with a capacity of 80 liters (stirring wing: 240φ, 55 mm x 57 mm, 2 stages, 4 blades) so that the deionized water reaches the polymerization kettle overflow port. 0.01 g of ferrous iron (Fe 2 SO 4 .7H 2 O) was added and the reaction solution was adjusted with sulfuric acid so that the pH was 3.0, and the temperature in the polymerization kettle was maintained at 57 ° C.
次に、重合開始５０分前から、単量体に対してレドックス重合開始剤である過硫酸アンモニウムを０．１０モル％、亜硫酸水素アンモニウムを０．３５モル％、硫酸第一鉄（Ｆｅ２ＳＯ４・７Ｈ２Ｏ）を０．３ｐｐｍ、硫酸を５．０×１０−２モル％となるように、それぞれ脱イオン交換水に溶解して連続的に供給し、攪拌速度１８０ｒｐｍ、攪拌動力１．２ｋＷ／ｍ３にて撹拌を行い、重合釜内での単量体の平均滞在時間が７０分になるように設定した。 Next, from 50 minutes before the start of the polymerization, 0.10 mol% of ammonium persulfate, which is a redox polymerization initiator, 0.35 mol% of ammonium bisulfite, and ferrous sulfate (Fe 2 SO 4) 7H 2 O) is 0.3 ppm and sulfuric acid is 5.0 × 10 −2 mol% dissolved in deionized water and continuously supplied, stirring speed 180 rpm, stirring power 1.2 kW / M 3 , and the average residence time of the monomer in the polymerization kettle was set to 70 minutes.
ついで、重合開始時に、アクリロニトリル（以下ＡＮと略す）単量体単位：アクリルアミド（以下ＡＡｍと略す）単量体単位：メタクリル酸（以下ＭＡＡと略す）単量体単位（質量比）＝９６．６５：３．３０：０．０５からなる単量体を水／単量体＝３（質量比）となるように、単量体の連続供給を開始した。その後、重合開始１時間後に重合反応温度を５０℃まで下げて温度を保持し、重合釜オーバーフロー口より連続的に重合体スラリーを取り出した。 Then, at the start of polymerization, acrylonitrile (hereinafter abbreviated as AN) monomer unit: acrylamide (hereinafter abbreviated as AAm) monomer unit: methacrylic acid (hereinafter abbreviated as MAA) monomer unit (mass ratio) = 96.65 : 3.30: 0.05 monomer was continuously fed so that water / monomer = 3 (mass ratio). Thereafter, 1 hour after the start of the polymerization, the polymerization reaction temperature was lowered to 50 ° C. to maintain the temperature, and the polymer slurry was continuously taken out from the polymerization kettle overflow port.
重合体スラリーには、シュウ酸ナトリウム０．３７×１０−２モル％、重炭酸ナトリウム１．７８×１０−２モル％を脱イオン交換水に溶解した重合停止剤水溶液を、重合スラリーのｐＨが５．５〜６．０になるように加えた。この重合スラリーをオリバー型連続フィルターによって脱水処理した後、重合体に対して１０倍量の脱イオン交換水（７０リットル）を加え、再び分散させた。再分散後の重合体スラリーを再度オリバー型連続フィルターによって脱水処理し、ペレット成形して、８０℃にて８時間、熱風循環型の乾燥機で乾燥後、ハンマーミルで粉砕し、ポリアクリロニトリル系共重合体を得た。表１に示したとおり、得られたポリアクリロニトリル系共重合体の組成、ポリアクリロニトリル系共重合体中のカルボキシル基の当量および酸化深さは表1に示したとおりとなった。 In the polymer slurry, an aqueous solution of a polymerization terminator in which sodium oxalate 0.37 × 10 −2 mol% and sodium bicarbonate 1.78 × 10 −2 mol% were dissolved in deionized water was used. It added so that it might become 5.5-6.0. The polymer slurry was dehydrated with an Oliver type continuous filter, and 10 times the amount of deionized water (70 liters) was added to the polymer and dispersed again. The polymer slurry after re-dispersion is again dehydrated with an Oliver type continuous filter, pelletized, dried at 80 ° C. for 8 hours in a hot air circulating dryer, pulverized with a hammer mill, and polyacrylonitrile-based copolymer. A polymer was obtained. As shown in Table 1, the composition of the obtained polyacrylonitrile copolymer, the equivalent of the carboxyl group in the polyacrylonitrile copolymer, and the oxidation depth were as shown in Table 1.
［炭素繊維前駆体繊維の製造］
このポリアクリロニトリル系共重合体をジメチルアセトアミド等の有機溶媒に濃度２１％になるように溶解してのポリアクリロニトリル系共重合体溶液を調製した。
[Production of carbon fiber precursor fiber]
This polyacrylonitrile copolymer was dissolved in an organic solvent such as dimethylacetamide so as to have a concentration of 21% to prepare a polyacrylonitrile copolymer solution.
得られたポリアクリロニトリル系共重合体溶液を用いて孔径６０μｍの紡糸ノズルより濃度５０質量％、温度３５℃のジメチルアセトアミド水溶液からなる凝固浴中に導入することで紡糸し、凝固糸を得た。得られた凝固糸を熱水中で５．０倍に延伸しながら洗浄、脱溶剤を行った。脱溶剤した凝固糸をアミノ変性シリコーン系油剤分散液中に浸漬し、１４０℃の加熱ローラーで緻密乾燥化した。このとき使用したアミノ変性シリコーン系油剤分散液は、アミノ変性シリコーン（信越化学工業株式会社製、商品名：ＫＦ−８００２）９０質量部に対し、乳化剤（花王株式会社製、商品名：エマルゲン１０８）を１０質量部混合したものをゴーリンミキサー（エスエムテー株式会社製、商品名：圧力式ホモジナイザーゴーリンタイプ）で乳化した後、水を加えて製造したもので、得られた油剤分散液の組成は、水：アミノ変性シリコーン：乳化剤（質量比）＝９８．６５：１．２：０．１５であった。次いで、表面温度１９０℃の熱ロールにて２．０倍に延伸し、捲取速度６０ｍ／分にて単繊維繊度２．５ｄｔｅｘ、フィラメント数２４０００の炭素繊維前駆体繊維を製造した。 The obtained polyacrylonitrile copolymer solution was spun by being introduced into a coagulation bath composed of an aqueous dimethylacetamide solution having a concentration of 50% by mass and a temperature of 35 ° C. from a spinning nozzle having a pore size of 60 μm, thereby obtaining a coagulated yarn. The obtained coagulated yarn was washed and desolvated while being stretched 5.0 times in hot water. The solvent-removed coagulated yarn was immersed in an amino-modified silicone oil dispersion and densely dried with a heating roller at 140 ° C. The amino-modified silicone oil dispersion used at this time was 90 parts by mass of amino-modified silicone (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-8002), and an emulsifier (trade name: Emulgen 108, manufactured by Kao Corporation). 10 parts by mass of the mixture was emulsified with a Gorin mixer (manufactured by SMT Co., Ltd., trade name: pressure homogenizer gorin type) and then added with water, and the composition of the resulting oil dispersion was water. : Amino-modified silicone: Emulsifier (mass ratio) = 98.65: 1.2: 0.15. Next, the carbon fiber precursor fiber having a single fiber fineness of 2.5 dtex and a filament number of 24,000 was produced at a drawing speed of 60 m / min by stretching 2.0 times with a hot roll having a surface temperature of 190 ° C.
得られた炭素繊維前駆体繊維について、熱流束型示差走査熱量計を用いて１０℃／分の昇温速度、エアー供給量１００ｍｌ／ｍｉｎの条件で、室温から４５０℃まで示差走査熱量測定をおこなった。得られた等速昇温発熱曲線について、２３０℃〜２６０℃の発熱量Ａ、２６０℃〜２９０℃の発熱量Ｂは表１に示したとおりであった。 The obtained carbon fiber precursor fiber was subjected to differential scanning calorimetry from room temperature to 450 ° C. using a heat flux type differential scanning calorimeter at a heating rate of 10 ° C./min and an air supply rate of 100 ml / min. It was. Table 1 shows the calorific value A of 230 ° C. to 260 ° C. and the calorific value B of 260 ° C. to 290 ° C. of the obtained constant speed heating exothermic curve.
（実施例２、３）
ポリアクリロニトリル系共重合体の組成を表１に示した値とした以外は実施例１と同様の方法でポリアクリロニトリル系重合体を得た。ポリアクリロニトリル系共重合体中のカルボキシル基の当量および酸化深さは表1に示した。
(Examples 2 and 3)
A polyacrylonitrile polymer was obtained in the same manner as in Example 1 except that the composition of the polyacrylonitrile copolymer was changed to the values shown in Table 1. Table 1 shows the equivalent amount and oxidation depth of the carboxyl group in the polyacrylonitrile-based copolymer.
これらの各ポリアクリロニトリル系重合体を用いて実施例１と同様にしてポリアクリロニトリル系共重合体溶液を調製した。
調整したポリアクリロニトリル系共重合体溶液を用いて実施例１と同様にして単繊維繊度２．５ｄｔｅｘ、フィラメント数２４０００の炭素繊維前駆体繊維を製造した。
Using each of these polyacrylonitrile polymers, a polyacrylonitrile copolymer solution was prepared in the same manner as in Example 1.
Using the prepared polyacrylonitrile copolymer solution, a carbon fiber precursor fiber having a single fiber fineness of 2.5 dtex and a filament count of 24,000 was produced in the same manner as in Example 1.
得られた炭素繊維前駆体繊維について、熱流束型示差走査熱量計を用いて１０℃／分の昇温速度、エアー供給量１００ｍｌ／ｍｉｎの条件で、室温から４５０℃まで示差走査熱量測定をおこなった。得られた等速昇温発熱曲線について、２３０℃〜２６０℃の発熱量である熱量Ａ、２６０℃〜２９０℃の発熱量である熱量Ｂは表１に示したとおりであった。 The obtained carbon fiber precursor fiber was subjected to differential scanning calorimetry from room temperature to 450 ° C. using a heat flux type differential scanning calorimeter at a heating rate of 10 ° C./min and an air supply rate of 100 ml / min. It was. Regarding the obtained constant-temperature heating exothermic curve, the calorific value A which is a calorific value of 230 ° C. to 260 ° C. and the calorific value B which is a calorific value of 260 ° C. to 290 ° C. are as shown in Table 1.
（比較例１、２）
ポリアクリロニトリル系共重合体の組成を表１に示した値とした以外は実施例１と同様の方法でポリアクリロニトリル系重合体を得た。ポリアクリロニトリル系共重合体中のカルボキシル基の当量および酸化深さは表1に示した。
(Comparative Examples 1 and 2)
A polyacrylonitrile polymer was obtained in the same manner as in Example 1 except that the composition of the polyacrylonitrile copolymer was changed to the values shown in Table 1. Table 1 shows the equivalent amount and oxidation depth of the carboxyl group in the polyacrylonitrile-based copolymer.
これらの各ポリアクリロニトリル系重合体を用いて実施例１と同様にしてポリアクリロニトリル系共重合体溶液を調製した。
調整したポリアクリロニトリル系共重合体溶液を用いて実施例１と同様にして単繊維繊度２．５ｄｔｅｘ、フィラメント数２４０００の炭素繊維前駆体繊維を製造した。
Using each of these polyacrylonitrile polymers, a polyacrylonitrile copolymer solution was prepared in the same manner as in Example 1.
Using the prepared polyacrylonitrile copolymer solution, a carbon fiber precursor fiber having a single fiber fineness of 2.5 dtex and a filament count of 24,000 was produced in the same manner as in Example 1.
得られた炭素繊維前駆体繊維について、熱流束型示差走査熱量計を用いて１０℃／分の昇温速度、エアー供給量１００ｍｌ／ｍｉｎの条件で、室温から４５０℃まで示差走査熱量測定をおこなった。得られた等速昇温発熱曲線について、２３０℃〜２６０℃の発熱量である熱量Ａ、２６０℃〜２９０℃の発熱量である熱量Ｂは表１に示したとおりであった。 The obtained carbon fiber precursor fiber was subjected to differential scanning calorimetry from room temperature to 450 ° C. using a heat flux type differential scanning calorimeter at a heating rate of 10 ° C./min and an air supply rate of 100 ml / min. It was. Regarding the obtained constant-temperature heating exothermic curve, the calorific value A which is a calorific value of 230 ° C. to 260 ° C. and the calorific value B which is a calorific value of 260 ° C. to 290 ° C. are as shown in Table 1.
Claims (6)
酸化深さＤの測定方法
１）前記ポリアクリロニトリル共重合体をジメチルホルムアミドに、質量濃度で２５％となるよう溶解させて共重合体溶液を得る。
２）前記共重合体溶液をガラス板上に一定の厚みになるように塗布する。
３）前記共重合体溶液を塗布したガラス板を、空気中１２０℃で６時間乾燥し、厚み２０〜４０μｍのフィルムとする。
４）得られたフィルムを、空気中２４０℃で６０分、さらに空気中２５０℃で６０分熱処理し、耐炎化処理を行う。
５）耐炎化処理したフィルムを樹脂包埋して、該樹脂を固化した上で、前記フィルム表面に対して垂直方向を研磨して断面を得て、そのフィルム断面を蛍光顕微鏡を用いて倍率１５００倍で観察する。
６）前記断面において酸化が進んだ部分は暗い層として、進んでいない部分は明るい層として観察されるので、フィルム表面から、暗い層と明るい層の境界までの距離を５点計測し、その算術平均を酸化深さＤ（μｍ）とする。 The polyacrylonitrile copolymer according to claim 1 or 2, wherein the oxidation depth D obtained by the following method is 3.5 to 4.5 µm. The method for measuring the oxidation depth D 1) The polyacrylonitrile copolymer A copolymer solution is obtained by dissolving in dimethylformamide so as to have a mass concentration of 25%.
2) The copolymer solution is applied on a glass plate so as to have a certain thickness.
3) The glass plate coated with the copolymer solution is dried in air at 120 ° C. for 6 hours to obtain a film having a thickness of 20 to 40 μm.
4) The obtained film is heat-treated at 240 ° C. in air for 60 minutes and further in air at 250 ° C. for 60 minutes to perform flameproofing treatment.
5) A flame-resistant film is embedded in a resin, and the resin is solidified, and then a cross section is obtained by polishing the direction perpendicular to the film surface. The cross section of the film is magnified 1500 using a fluorescence microscope. Observe at double.
6) In the cross section, the portion where oxidation has progressed is observed as a dark layer, and the portion where oxidation has not progressed is observed as a bright layer. Therefore, the distance from the film surface to the boundary between the dark layer and the bright layer is measured at five points. The average is defined as oxidation depth D (μm).
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| CN110305247A (en) * | 2019-07-24 | 2019-10-08 | 长春工业大学 | A kind of polyacrylonitrile base carbon fiber precursors polymer and preparation method thereof, a kind of polyacrylonitrile-based carbon fibre and preparation method thereof |
| CN110305247B (en) * | 2019-07-24 | 2021-09-14 | 长春工业大学 | Polyacrylonitrile-based carbon fiber precursor polymer and preparation method thereof, and polyacrylonitrile-based carbon fiber and preparation method thereof |
| EP3795726A1 (en) | 2019-09-19 | 2021-03-24 | Toyota Jidosha Kabushiki Kaisha | Stabilized fiber, method of producing the same, and method of producing carbon fiber |
| US11702769B2 (en) | 2019-09-19 | 2023-07-18 | Toyota Jidosha Kabushiki Kaisha | Stabilized fiber, method of producing the same, and method of producing carbon fiber |
| EP4060101A2 (en) | 2021-03-18 | 2022-09-21 | Kabushiki Kaisha Toyota Chuo Kenkyusho | Carbon fiber and method for producing the same |
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