JPH09279154A - Pitch for carbon fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pitch for carbon fiber, capable of providing pitch-based carbon fiber not only having high rigidity and high strength, but improved also in compression physical property. SOLUTION: This pitch for carbon fiber is obtained by polymerizing a condensed polycyclic hydrocarbon in the presence of hydrogen fluoride and boron trifluoride at 100-400οC to afford optically isotropic pitch or optically anisotropic pitch having <5% optically anisotropic phase content and further thermally polymerizing the pitch at 250-400 deg.C. The pitch has 0.5-0.7 atom ratio of hydrogen to carbon, <=50% oriented carbon amount among whole aromatic carbon, 5-60% anisotropic sphere with 5-150μm diameter and <=25wt.% pyridine-insoluble content.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【発明の属する技術分野】本発明は炭素繊維用ピッチに
関し、特に圧縮物性に優れたピッチ系炭素繊維を提供し
うる炭素繊維用ピッチに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pitch for carbon fibers, and more particularly to a pitch for carbon fibers which can provide pitch-based carbon fibers having excellent compression properties.

【０００２】[0002]

【従来の技術】ピッチを原料として高強度、高弾性の炭
素繊維を製造する方法が種々検討されており、特に光学
的異方性相が８５％以上のピッチが高強度、高弾性率の
炭素繊維を得る上で好ましいことが知られている。しか
し、このようなピッチから得られた炭素繊維は高温焼成
に伴う黒鉛結晶の発達により、高弾性率化は達成できる
ものの、圧縮強度が低くなるという問題がある。黒鉛結
晶の高度の発達は、繊維に圧縮応力がかかったときに、
結晶の界面での剥離を生じやすくし、その結果圧縮強度
が低く制限される。このためピッチ系炭素繊維を用いた
複合材料（ＣＦＲＰ）はポリアクリルニトリル（ＰＡ
Ｎ）系炭素繊維を用いたＣＦＲＰに比べ、その圧縮特
性、特に圧縮強度が劣るという問題点があり、ピッチ系
炭素繊維の優れた剛性を利用した薄物材料としての特徴
を活かし切れていないのが現状である。2. Description of the Related Art Various methods for producing high-strength, high-elasticity carbon fibers using pitch as a raw material have been investigated. Particularly, pitches having an optically anisotropic phase of 85% or more have high strength and high elastic modulus. It is known to be preferable for obtaining fibers. However, although carbon fibers obtained from such pitches can achieve a high modulus of elasticity due to the development of graphite crystals accompanying high-temperature sintering, there is a problem that the compressive strength is low. The high degree of development of graphite crystals, when the fiber is subjected to compressive stress,
Delamination is likely to occur at the crystal interface, resulting in low compressive strength. For this reason, the composite material (CFRP) using pitch-based carbon fiber is polyacrylonitrile (PA
N) has a problem that its compression characteristics, especially compression strength, are inferior to those of CFRP using carbon fibers, and the characteristics of the pitch carbon fibers as a thin material utilizing the excellent rigidity cannot be fully utilized. The current situation.

【０００３】[0003]

【発明が解決しようとする課題】本発明の目的は高剛性
・高強度を有するのみならず、圧縮物性にも優れたピッ
チ系炭素繊維を得ることができる炭素繊維用ピッチを提
供することにある。SUMMARY OF THE INVENTION It is an object of the present invention to provide a pitch for carbon fibers, which can obtain pitch-based carbon fibers not only having high rigidity and high strength but also excellent in compression properties. .

【０００４】[0004]

【課題を解決するための手段】即ち、本発明は縮合多環
炭化水素をフッ化水素および三フッ化ホウ素の存在下、
１００〜４００℃で重合させて光学的等方性ピッチもし
くは光学的異方性相含有量５％未満のピッチを得た後、
更に２５０〜４５０℃で熱重合して得られる、炭素に対
する水素の原子比が０．５〜０．７、全芳香族炭素のう
ち配向炭素量が５０％以下、５〜１５０μｍの異方性球
体が５〜６０％、ピリジン不溶分が２５重量％以下であ
る炭素繊維用ピッチに関する。本発明の炭素繊維用ピッ
チを用いれば、従来のＰＡＮ系と同等の圧縮強度を得る
ことさえ困難とされてきたピッチ系炭素繊維において、
高弾性率領域では同等どころかはるかに凌駕し、ＰＡＮ
系炭素繊維でさえ達成し得なかった圧縮強度を得ること
が可能となる。以下に本発明を詳述する。[Means for Solving the Problems] That is, the present invention provides a condensed polycyclic hydrocarbon in the presence of hydrogen fluoride and boron trifluoride.
After polymerization at 100 to 400 ° C. to obtain an optically isotropic pitch or a pitch having an optically anisotropic phase content of less than 5%,
Anisotropic spheres having an atomic ratio of hydrogen to carbon of 0.5 to 0.7, an amount of oriented carbon of 50% or less of all aromatic carbons, and 5 to 150 μm, which are obtained by thermal polymerization at 250 to 450 ° C. Is 5 to 60% and the pyridine insoluble content is 25% by weight or less. If the pitch for carbon fiber of the present invention is used, it is difficult to obtain a compressive strength equivalent to that of a conventional PAN-based pitch carbon fiber,
Far higher than even in the high elastic modulus range, PAN
It is possible to obtain a compressive strength that could not be achieved even with carbon-based fibers. Hereinafter, the present invention will be described in detail.

【０００５】[0005]

【発明の実施の形態】本発明において縮合多環炭化水素
としては、好ましくは２〜４環の縮合多環炭化水素が用
いられる。該縮合多環炭化水素の具体例としては、ナフ
タレン、アントラセン、フェナントレン、アセナフテ
ン、アセナフチレン、ピレン等およびこれらの混合物等
が挙げられる。また本発明においては該縮合多環炭化水
素を通常１０ｗｔ％以上、好ましくは３０ｗｔ％以上含
有する物質を用いることができる。これらの例としては
種々の石油留分、石油加工工程の残油および石炭タール
留分等を挙げることができる。これらの縮合多環炭化水
素の重合用触媒としてはフッ化水素および三フッ化ホウ
素が用いられる。該重合触媒は、縮合多環炭化水素１モ
ルに対し、フッ化水素が通常０．１〜２０モル、三フッ
化ホウ素が通常０．０５〜１．０モル用いられる。BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a condensed polycyclic hydrocarbon having 2 to 4 rings is preferably used as the condensed polycyclic hydrocarbon. Specific examples of the condensed polycyclic hydrocarbon include naphthalene, anthracene, phenanthrene, acenaphthene, acenaphthylene, pyrene and the like, and mixtures thereof. In the present invention, a substance containing the condensed polycyclic hydrocarbon in an amount of usually 10 wt% or more, preferably 30 wt% or more can be used. Examples of these include various petroleum fractions, residual oil from petroleum processing, coal tar fractions, and the like. Hydrogen fluoride and boron trifluoride are used as catalysts for polymerizing these condensed polycyclic hydrocarbons. In the polymerization catalyst, hydrogen fluoride is usually used in an amount of 0.1 to 20 mol and boron trifluoride is usually used in an amount of 0.05 to 1.0 mol, based on 1 mol of the condensed polycyclic hydrocarbon.

【０００６】なお、本発明においては、フッ化水素と三
フッ化ホウ素はそれぞれ単独では重合触媒として有効で
はなく、両者を組み合わせることが必要である。重合反
応は、例えば攪拌機を備えた耐酸化性の反応器中に上記
原料及び上記触媒を供給し、攪拌混合下で行なうことが
できる。重合温度は通常１００〜４００℃であり、好ま
しくは１５０〜２４０℃である。温度が４００℃を越え
ると重合が過度に進行するため、得られるピッチの軟化
点が高くなる。また、１００℃より低い温度では、反応
時間が長くなり経済的でない。重合に要する時間は原料
の種類、温度および触媒の量によって変化するが、通常
５〜３００分であり、好ましくは３０〜２４０分であ
る。また重合圧力は、通常０．５〜１０ＭＰａ、好まし
くは０．５〜５ＭＰａ、より好ましくは０．５〜２．４
ＭＰａである。重合終了後、触媒は除去、回収するのが
望ましい。触媒を除去、回収する方法としては回分的も
しくは連続的に留去する方法を用いることができ、重合
反応後、通常０〜３ＭＰａ、好ましくは０〜０．５ＭＰ
ａの圧力下ガス状にして回収することができる。このと
き同時に反応生成物の軽質分を除去することもできる。In the present invention, hydrogen fluoride and boron trifluoride alone are not effective as polymerization catalysts, and it is necessary to combine both. The polymerization reaction can be carried out, for example, by supplying the above-mentioned raw materials and the above-mentioned catalyst into an oxidation-resistant reactor equipped with a stirrer and stirring and mixing. The polymerization temperature is usually 100 to 400 ° C, preferably 150 to 240 ° C. If the temperature exceeds 400 ° C., the polymerization will proceed excessively and the softening point of the obtained pitch will be high. Further, if the temperature is lower than 100 ° C., the reaction time becomes long and it is not economical. The time required for polymerization varies depending on the type of raw material, temperature and amount of catalyst, but is usually 5 to 300 minutes, preferably 30 to 240 minutes. The polymerization pressure is usually 0.5 to 10 MPa, preferably 0.5 to 5 MPa, and more preferably 0.5 to 2.4.
MPa. It is desirable to remove and recover the catalyst after the completion of the polymerization. As a method of removing and recovering the catalyst, a method of distilling off in a batchwise or continuous manner can be used, and usually 0 to 3 MPa, preferably 0 to 0.5 MP after the polymerization reaction.
It can be recovered as a gas under the pressure of a. At this time, the light components of the reaction product can be simultaneously removed.

【０００７】次いで、上記重合反応により得られた光学
的に等方性のピッチもしくは光学的異方性相含有量５％
未満、好ましくは３％以下のピッチをさらに常圧もしく
は減圧下に熱重合を施し、光学的異方性相含有量５％以
上にまで光学的異方性ピッチ化する。熱重合温度は通常
２５０〜４５０℃、好ましくは３００〜４２０℃で時間
は通常０．５〜３０時間、好ましくは３〜２５時間であ
る。熱重合に際しては、窒素ガス等の不活性ガスを通気
しながら重合を行なうことも好ましい。該熱重合反応に
よって得られる炭素繊維用ピッチは、通常炭素に対する
水素の原子比が０．５〜０．７、全芳香族炭素量のうち
配向炭素量が５０％以下、５〜１５０μｍの光学的異方
性球体が５〜６０％、好ましくは５〜５０％で、ピリジ
ン不溶分が２５重量％以下であるという特徴を有する。Next, the content of optically isotropic pitch or optically anisotropic phase obtained by the above polymerization reaction is 5%.
Pitch of less than 3%, preferably less than 3%, is further subjected to thermal polymerization under normal pressure or reduced pressure to form optically anisotropic pitch to an optically anisotropic phase content of 5% or more. The thermal polymerization temperature is usually 250 to 450 ° C., preferably 300 to 420 ° C., and the time is usually 0.5 to 30 hours, preferably 3 to 25 hours. In the thermal polymerization, it is also preferable to carry out the polymerization while aerating an inert gas such as nitrogen gas. The pitch for carbon fibers obtained by the thermal polymerization reaction usually has an atomic ratio of hydrogen to carbon of 0.5 to 0.7, an oriented carbon content of 50% or less of the total aromatic carbon content, and an optical content of 5 to 150 μm. The anisotropic spheres are 5 to 60%, preferably 5 to 50%, and the pyridine insoluble content is 25% by weight or less.

【０００８】本発明における炭素および水素の測定は、
燃焼ガスの熱伝導度による検出などの技術を応用した自
動分析装置（ＣＨＮコーダー）を用いて行なわれる。本
発明においても光学的異方性ピッチとは、偏光顕微鏡で
ピッチの断面を観察した際に見ることができる光学的異
方性を示す球晶部分（光学的異方性相という）を含有す
るピッチであり、その含有量は観察したピッチ断面全体
の面積に対する光学的異方性の球晶の面積分率で示す。The measurement of carbon and hydrogen in the present invention is
It is performed using an automatic analyzer (CHN coder) to which a technique such as detection based on the thermal conductivity of combustion gas is applied. Also in the present invention, the optically anisotropic pitch contains a spherulite portion (referred to as an optically anisotropic phase) that exhibits optical anisotropy that can be seen when observing the cross section of the pitch with a polarization microscope. Pitch, and the content thereof is indicated by the area fraction of optically anisotropic spherulites with respect to the entire area of the observed pitch cross section.

【０００９】配向炭素量の測定は、公知の方法〔西沢、
第１４回炭素材料科学会年会、１Ａ１５（１９８７）〕
に準拠して¹³Ｃ−ＮＭＲ（Ｂｒｕｋｅｒ社製、ＭＳＬ−
３００型）で行う。試料約０．５ｇを内径９ｍｍの高温
ＮＭＲ用サンプル管に採取し、高温用ブローブヘッド内
に入れ、窒素気流中昇温速度５℃／ｍｉｎで加熱し、軟
化点プラス６０℃の条件で測定した。スペクトルは大き
く３つに分け得る。第一は、１０〜４０ｐｐｍに見られ
るアリファティク炭素のシグナルである。他の２つは、
１３０ｐｐｍ及び１８０ｐｐｍを中心としたアロマティ
ク炭素のシグナルである。そして、アロマティクシグナ
ル中１３０ｐｐｍのシグナルは配向していない分子のア
ロマティク炭素であり、一方１８０ｐｐｍのシグナルは
配向した分子のアロマティク炭素である。配向炭素量は
以下の式により求められる。The amount of oriented carbon is measured by a known method [Nishizawa,
14th Annual Meeting of Carbon Material Science Society, 1A15 (1987)]
¹³ C-NMR (manufactured by Bruker, MSL-
(Type 300). About 0.5 g of a sample was collected in a high-temperature NMR sample tube having an inner diameter of 9 mm, placed in a high-temperature probe head, heated in a nitrogen stream at a heating rate of 5 ° C / min, and measured at a softening point plus 60 ° C. . The spectrum can be roughly divided into three. The first is the signal of the aliphatic carbon found at 10-40 ppm. The other two are
It is a signal of aromatic carbon centering around 130 ppm and 180 ppm. And the signal of 130 ppm in the aromatic signal is the aromatic carbon of the unoriented molecule, while the signal of 180 ppm is the aromatic carbon of the oriented molecule. The amount of oriented carbon is calculated by the following formula.

【００１０】[0010]

【数１】 [Equation 1]

【００１１】かくして、得られた紡糸用ピッチは押出
法、遠心法等の公知の方法で溶融紡糸を行いピッチ繊維
とすることができる。ピリジン不溶分はソックスレー抽
出器により沸騰ピリジン中に抽出した後のピリジン不溶
分の重量％から求められる。溶融紡糸は公知の条件下に
行い得るが、本発明の目的とする圧縮物性に優れた炭素
繊維を得るためには通常溶融粘度を２０〜９００Ｐａ・
Ｓとし、巻取速度１００〜１０００ｍ／分、巻取張力２
０〜１００ｍｇ／本の条件が好ましく採用される。Thus, the obtained spinning pitch can be melt-spun by a known method such as an extrusion method or a centrifugal method to obtain pitch fibers. The pyridine-insoluble matter is obtained from the weight% of the pyridine-insoluble matter after being extracted into boiling pyridine with a Soxhlet extractor. Melt spinning can be carried out under known conditions, but in order to obtain the carbon fiber excellent in compressed physical properties which is the object of the present invention, the melt viscosity is usually 20 to 900 Pa.
S, winding speed 100 to 1000 m / min, winding tension 2
The condition of 0 to 100 mg / piece is preferably adopted.

【００１２】溶融紡糸して得られたピッチ繊維は、次に
酸化性ガス雰囲気下で不融化処理が施される。酸化性ガ
スとしては、通常、酸素、オゾン、空気、窒素酸化物、
ハロゲン、亜硫酸ガス等の酸化性ガスを１種あるいは２
種以上用いる。この不融化処理は、被処理体であるピッ
チ繊維が軟化変形しない温度条件下で実施される。例え
ば２０〜３６０℃、好ましくは６０〜３００℃が採用さ
れる。また処理時間は通常５分〜６時間である。不融化
処理されたピッチ繊維は、次に不活性ガス雰囲気下で炭
化処理が施されてピッチ系炭素繊維となる。炭化は通常
５００℃〜３５００℃、好ましくは８００〜３０００℃
で行なう。炭化処理に要する時間は通常０．１分〜１０
時間である。かくして得られるピッチ系炭素繊維は、引
張強度が通常２．５〜５ＧＰａ、引張弾性率が通常４５
０〜１０００ＧＰａ、圧縮強度が通常６００〜２０００
ＭＰａを有しており、炭素繊維の断面は通常ランダム構
造を有している。炭素繊維の圧縮強度の評価法に関して
は単繊維樹脂埋め込み法、Ｔｅｎｓｉｌｅ Ｒｅｃｏｉ
ｌ法、Ｋｎｏｔ法等が提案されているが、本発明者らは
Ｔｅｎｓｉｌｅ Ｒｅｃｏｉｌ法（Ｓ．Ｒ．Ａｌｌｅ
ｎ，Ｊ．Ｍａｔｅｒ．Ｓｃｉ，２２，８５３（１９８
７））を採用した。The pitch fiber obtained by melt spinning is then subjected to infusibilization treatment in an oxidizing gas atmosphere. The oxidizing gas is usually oxygen, ozone, air, nitrogen oxides,
One or two oxidizing gases such as halogen and sulfurous acid gas
Use more than one species. This infusibilization treatment is performed under a temperature condition under which the pitch fibers as the object to be treated are not softened and deformed. For example, 20 to 360 ° C, preferably 60 to 300 ° C is adopted. The processing time is usually 5 minutes to 6 hours. The infusibilized pitch fiber is then carbonized in an inert gas atmosphere to become pitch-based carbon fiber. Carbonization is usually 500 ° C to 3500 ° C, preferably 800 to 3000 ° C.
Perform in. The time required for carbonization is usually 0.1 minutes to 10 minutes.
Time. The pitch-based carbon fiber thus obtained has a tensile strength of usually 2.5 to 5 GPa and a tensile modulus of 45.
0 to 1000 GPa, compressive strength is usually 600 to 2000
It has MPa, and the cross section of the carbon fiber usually has a random structure. Regarding the evaluation method of the compressive strength of carbon fiber, the single fiber resin embedding method, Tensile Recoi
Although the l method, the Knot method, etc. have been proposed, the present inventors have proposed the Tensile Recoil method (SR Alle method).
n, J. et al. Mater. Sci, 22, 853 (198
7)) was adopted.

【００１３】[0013]

【発明の効果】実施例からも明らかなように本発明の炭
素繊維用ピッチを用いて得られるピッチ系炭素繊維は引
張強度および引張弾性率に優れているのみならず、圧縮
強度が高いという特徴を有する。As is clear from the examples, the pitch-based carbon fiber obtained by using the pitch for carbon fiber of the present invention is not only excellent in tensile strength and tensile elastic modulus, but also has high compression strength. Have.

【００１４】[0014]

【実施例】以下に実施例を挙げ本発明を具体的に説明す
るが、本発明はこれらに制限されるものではない。EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

【００１５】（実施例１）ナフタレン７モル、フッ化水
素１．４モル、三フッ化ホウ素０．７７モルを３Ｌの耐
酸オートクレーブに仕込み、１．９ＭＰａの圧力下２１
０℃へ昇温後、４時間反応させ光学的等方性ピッチを得
た。その後、オートクレーブの放出弁を開け、常圧にお
いて実質的に全量のフッ化水素、三フッ化ホウ素をガス
状で回収した後、窒素を吹き込み、低沸点成分を除去し
たピッチＡを得た。ピッチＡの収率は原料ナフタレンに
対して６５重量％、軟化点は１７０℃であった。このピ
ッチＡ、３０ｇに対し、常圧下、窒素を６００ｍｌ／分
で通気しながら攪拌し、３８０℃で２３時間処理を行な
って光学的異方性ピッチ化を行い、軟化点２１７℃、炭
素に対する水素の比０．５９、配向炭素量２５％、平均
粒径６０μｍの異方性球体含有率５０％、ピリジン不溶
分１８％のピッチＢを得た。かく調製された紡糸用ピッ
チＢをノズル径０．３φ、Ｌ／Ｄ＝１の紡糸器を用い、
溶融粘度２５０Ｐａ・ｓで紡糸し、糸径１３μｍのピッ
チ繊維を得た。次いで、ピッチ繊維をＮＯ₂ を３ｖｏｌ
％含有する空気中で１℃／分で２５０℃まで昇温し１時
間保持した後、窒素中で５℃／分で７００℃まで昇温
し、さらに２５℃／分で２５００℃まで昇温して加熱処
理を行い１０μｍの炭素繊維を得た。得られた炭素繊維
の引張強度は３８００ＭＰａ、弾性率は７５０ＧＰａ、
圧縮強度は７５０ＭＰａであった。この炭素繊維の断面
構造は微細なランダム構造であった。(Example 1) 7 mol of naphthalene, 1.4 mol of hydrogen fluoride, and 0.77 mol of boron trifluoride were charged into a 3 L acid-resistant autoclave, and a pressure of 1.9 MPa was applied.
After the temperature was raised to 0 ° C., the reaction was carried out for 4 hours to obtain an optically isotropic pitch. Then, the discharge valve of the autoclave was opened, and substantially all amounts of hydrogen fluoride and boron trifluoride were collected in a gaseous state at atmospheric pressure, and then nitrogen was blown into the obtained mixture to obtain pitch A from which low-boiling components were removed. The yield of pitch A was 65% by weight with respect to the raw material naphthalene, and the softening point was 170 ° C. With respect to this pitch A (30 g), nitrogen was aerated under normal pressure at 600 ml / min, and the mixture was treated at 380 ° C. for 23 hours to form an optically anisotropic pitch, with a softening point of 217 ° C. and hydrogen to carbon. Pitch B having a ratio of 0.59, an oriented carbon amount of 25%, an anisotropic sphere content of 50% with an average particle size of 60 μm, and a pyridine insoluble content of 18% was obtained. The spinning pitch B thus prepared was used with a spinning machine having a nozzle diameter of 0.3φ and L / D = 1.
Spinning was performed at a melt viscosity of 250 Pa · s to obtain pitch fibers having a yarn diameter of 13 μm. Next, the pitch fiber is mixed with 3 vol of NO ₂ .
% In air containing 1% / min up to 250 ° C and holding for 1 hour, then in nitrogen at 5 ° C / min up to 700 ° C and further 25 ° C / min up to 2500 ° C. And heat treatment was performed to obtain 10 μm carbon fibers. The tensile strength of the obtained carbon fiber is 3800 MPa, the elastic modulus is 750 GPa,
The compressive strength was 750 MPa. The cross-sectional structure of this carbon fiber was a fine random structure.

【００１６】（実施例２）ナフタレン７モル、フッ化水
素３．１５モル、三フッ化ホウ素１．２モルを３Ｌの耐
酸オートクレーブに仕込み、２．１ＭＰａの圧力下２０
０℃へ昇温後、４時間反応した。その後、オートクレー
ブの放出弁を開け、常圧において実質的に全量のフッ化
水素、三フッ化ホウ素をガス状で回収した後、窒素を吹
き込み、低沸点成分を除去したピッチＣを得た。ピッチ
Ｃの収率は原料ナフタレンに対して７０重量％、軟化点
は１７２℃であった。このピッチＣ、３０ｇに対し、窒
素を６００ｍｌ／分で通気しながら攪拌し、３８０℃で
１２時間処理を行なって、軟化点２０５℃、炭素に対す
る水素の比０．６２、配向炭素量８％、平均粒径４５μ
ｍの異方性球体含有率３０％、ピリジン不溶分１４％の
ピッチＤを得た。かく調製された紡糸用ピッチＤを実施
例１の紡糸器を用い、溶融粘度１００Ｐａ・ｓで糸径１
３μｍのピッチ繊維を得た。次いで、実施例１と同様の
方法で不融化、炭化処理して９．５μｍの炭素繊維を得
た。得られた炭素繊維の引張強度は３５００ＭＰａ、弾
性率は６００ＧＰａ、圧縮強度は８３０ＭＰａであっ
た。この炭素繊維の断面構造は微細なランダム構造であ
った。(Example 2) 7 mol of naphthalene, 3.15 mol of hydrogen fluoride and 1.2 mol of boron trifluoride were charged into a 3 L acid-resistant autoclave, and a pressure of 2.1 MPa was applied to the mixture.
After the temperature was raised to 0 ° C., the reaction was performed for 4 hours. Then, the discharge valve of the autoclave was opened, and substantially all amounts of hydrogen fluoride and boron trifluoride were collected in a gaseous state at atmospheric pressure, and then nitrogen was blown into the mixture to obtain a pitch C from which low-boiling components were removed. The yield of pitch C was 70% by weight with respect to the raw material naphthalene, and the softening point was 172 ° C. The pitch C, 30 g, was agitated while nitrogen was bubbled at 600 ml / min, and treated at 380 ° C. for 12 hours to give a softening point of 205 ° C., a hydrogen to carbon ratio of 0.62, and an oriented carbon amount of 8%. Average particle size 45μ
A pitch D having an anisotropic sphere content of m of 30% and a pyridine insoluble content of 14% was obtained. Using the spinning machine of Example 1, the spinning pitch D thus prepared was melted at a viscosity of 100 Pa · s and a yarn diameter of 1
3 μm pitch fiber was obtained. Then, infusibilization and carbonization treatment were carried out in the same manner as in Example 1 to obtain 9.5 μm carbon fibers. The tensile strength of the obtained carbon fiber was 3500 MPa, the elastic modulus was 600 GPa, and the compressive strength was 830 MPa. The cross-sectional structure of this carbon fiber was a fine random structure.

【００１７】（実施例３）実施例２で用いたピッチＣ、
３０ｇに対し、常圧下窒素を６００ｍｌ／分で通気しな
がら攪拌し、３８０℃で８時間処理を行って、軟化点１
９８℃、炭素に対する水素の比０．６４、配向炭素量０
％、平均粒径３０μｍの異方性球体含有率１０％、ピリ
ジン不溶分７％のピッチＥを得た。かく調製された紡糸
用ピッチＥを実施例１の紡糸器を用い、溶融粘度３５０
Ｐａ・ｓで糸径１３μｍのピッチ繊維を得た。次いで、
実施例１と同様の方法で不融化、炭化処理して９．２μ
ｍの炭素繊維を得た。得られた炭素繊維の引張強度は３
０００ＭＰａ、弾性率は５２０ＧＰａ、圧縮強度は９１
５ＭＰａであった。この炭素繊維の断面構造は微細なラ
ンダム構造であった。(Example 3) Pitch C used in Example 2,
With respect to 30 g, nitrogen was bubbled under normal pressure at 600 ml / min, and the mixture was stirred and treated at 380 ° C. for 8 hours to give a softening point of 1
98 ° C., hydrogen to carbon ratio 0.64, oriented carbon amount 0
%, The content of anisotropic spheres having an average particle diameter of 30 μm was 10%, and the pitch E insoluble in pyridine was 7%. The spinning pitch E thus prepared was melted with a melt viscosity of 350 using the spinning machine of Example 1.
Pitch fibers having a yarn diameter of 13 μm at Pa · s were obtained. Then
9.2μ after infusibilization and carbonization treatment in the same manner as in Example 1
m carbon fiber was obtained. The tensile strength of the obtained carbon fiber is 3
000 MPa, elastic modulus 520 GPa, compressive strength 91
It was 5 MPa. The cross-sectional structure of this carbon fiber was a fine random structure.

【００１８】（比較例１）市販の石油ピッチ（Ａ−２４
０）３０ｇに対し、常圧下窒素を６００ｍｌ／分で通気
しながら攪拌し、４１０℃で７時間処理を行って、軟化
点２３５℃、平均粒径３５μｍの異方性球体含有率２０
％、のピッチＦを得た。かく調製された紡糸用ピッチＦ
を実施例１の紡糸器を用い、溶融粘度２５０Ｐａ・ｓで
紡糸を行ったが、繊維状のものが満足に得られなかっ
た。Comparative Example 1 Commercially available petroleum pitch (A-24
0) 30 g of nitrogen was agitated at 600 ml / min under normal pressure while stirring, and treated at 410 ° C. for 7 hours to give a softening point of 235 ° C. and an average particle size of 35 μm anisotropic sphere content 20.
%, The pitch F was obtained. The spinning pitch F thus prepared
Using the spinning machine of Example 1, spinning was performed at a melt viscosity of 250 Pa · s, but a fibrous product was not satisfactorily obtained.

【００１９】（比較例２）ナフタレンと、その１０％に
相当する塩化アルミニウムをガラス製三口フラスコに仕
込み窒素雰囲気、常圧下で１８０℃、１２時間重合反応
を行った。重合終了後、水洗、濾過を行って触媒を除去
し、等方性のピッチＧを得た。このピッチＧ、３０ｇに
対し、窒素を６００ｍｌ／分で通気しながら攪拌し、４
００℃で１５時間処理を行って、軟化点２１５℃、平均
粒径７５μｍの異方性球体含有率２５％のピッチＨを得
た。かく調製された紡糸用ピッチＨを実施例１の紡糸器
を用い、溶融粘度１００Ｐａ・ｓで紡糸を行ったが、安
定に紡糸することができず、また表面が凸凹の繊維しか
得られなかった。(Comparative Example 2) Naphthalene and aluminum chloride corresponding to 10% thereof were charged in a glass three-necked flask and a polymerization reaction was carried out at 180 ° C for 12 hours under a nitrogen atmosphere and normal pressure. After the polymerization was completed, the catalyst was removed by washing with water and filtration to obtain isotropic pitch G. Nitrogen was aerated at a rate of 600 ml / min to the pitch G of 30 g, and the mixture was mixed with 4
A treatment was carried out at 00 ° C. for 15 hours to obtain pitch H having a softening point of 215 ° C., an average particle diameter of 75 μm, and an anisotropic sphere content of 25%. The thus-prepared spinning pitch H was spun at a melt viscosity of 100 Pa · s using the spinning machine of Example 1, but stable spinning was not possible, and only fibers having an uneven surface were obtained. .

【００２０】（比較例３）ナフタレン７モル、フッ化水
素１．４モル、三フッ化ホウ素０．７７モルを３Ｌの耐
酸オートクレーブに仕込み、２．５ＭＰａに加圧して２
３０℃へ昇温後、１時間熱重合した。その後、オートク
レーブの放出弁を開け、常圧において実質的に全量のフ
ッ化水素、三フッ化ホウ素をガス状で回収した後、窒素
を吹き込み、低沸点成分を除去したピッチＩを得た。得
られたピッチは軟化点２０６℃、炭素に対する水素の比
０．６８、配向炭素量１５％、平均粒径１１０μｍの異
方性球体含有率４５％、ピリジン不溶分２５％であっ
た。かく調製された紡糸用ピッチＩを実施例１の紡糸器
を用い、溶融粘度２５０Ｐａ・ｓで紡糸を行ったが、安
定に紡糸することができなかった。(Comparative Example 3) 7 mol of naphthalene, 1.4 mol of hydrogen fluoride and 0.77 mol of boron trifluoride were charged into a 3 L acid-resistant autoclave and pressurized to 2.5 MPa to 2
After the temperature was raised to 30 ° C., thermal polymerization was performed for 1 hour. Then, the discharge valve of the autoclave was opened, and substantially all amounts of hydrogen fluoride and boron trifluoride were collected in a gaseous state at atmospheric pressure, and then nitrogen was blown into the obtained mixture to obtain pitch I in which low-boiling components were removed. The obtained pitch had a softening point of 206 ° C., a hydrogen to carbon ratio of 0.68, an oriented carbon amount of 15%, an anisotropic sphere content of 45% with an average particle diameter of 110 μm, and a pyridine insoluble content of 25%. The spinning pitch I thus prepared was spun at a melt viscosity of 250 Pa · s using the spinning machine of Example 1, but stable spinning could not be performed.

───────────────────────────────────────────────────── フロントページの続き (72)発明者 吉村 貴史 茨城県つくば市和台22 三菱瓦斯化学株式 会社総合研究所内 (72)発明者 酒井 幸男 茨城県つくば市和台22 三菱瓦斯化学株式 会社総合研究所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Yoshimura 22 Taidai, Tsukuba, Ibaraki Mitsubishi Gas Chemical Co., Ltd. (72) Inventor Yukio Sakai 22 Wadai, Tsukuba, Ibaraki Mitsubishi Gas Chemical Co., Ltd. In-house

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】 縮合多環炭化水素をフッ化水素および三
フッ化ホウ素の存在下、１００〜４００℃で重合させて
光学的等方性ピッチもしくは光学的異方性相含有量５％
未満のピッチを得た後、更に２５０〜４５０℃で熱重合
して得られる、炭素に対する水素の原子比が０．５〜
０．７、全芳香族炭素のうち配向炭素量が５０％以下、
５〜１５０μｍの異方性球体が５〜６０％、ピリジン不
溶分が２５重量％以下である炭素繊維用ピッチ。1. An optically isotropic pitch or optically anisotropic phase content of 5% by polymerizing a condensed polycyclic hydrocarbon in the presence of hydrogen fluoride and boron trifluoride at 100 to 400 ° C.
After obtaining a pitch of less than 0.5, the atomic ratio of hydrogen to carbon obtained by further heat-polymerizing at 250 to 450 ° C. is 0.5 to
0.7, the total amount of oriented carbon in the aromatic carbon is 50% or less,
A pitch for carbon fibers having 5 to 60% of anisotropic spheres of 5 to 150 μm and 25% by weight or less of pyridine insoluble matter.